genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults
TRANSCRIPT
![Page 1: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/1.jpg)
REVIEWARTICLE
Genes, Chromosomes and the Developmentof Testicular Germ Cell Tumors of Adolescentsand Adults
Alan McIntyre,1 Duncan Gilbert,1 Neil Goddard,1 Leendart Looijenga,2 and Janet Shipley1*
1Molecular Cytogenetics,Section of Molecular Carcinogenesis,The Institute of Cancer Research,Sutton,Surrey,SM2 5NG,UK2Departmentof Pathology,Erasmus MC-University Medical Center Rotterdam,Daniel den Hoed Cancer Center,Josephine Nefkens Institute, 3000 DRRotterdam,The Netherlands
Testicular germ cell tumors (TGCTs) of adults and adolescents are thought to be derived from primordial germ cells or gono-
cytes. TGCTs develop postpuberty from precursor lesions known as intratubular germ cell neoplasia undifferentiated. The
tumors can be divided into two groups based on their histology and clinical behavior; seminomas resemble primordial germ
cells or gonocytes and nonseminomas resemble embryonic or extraembryonic tissues at various stages of differentiation. The
most undifferentiated form of nonseminoma, embryonal carcinoma, resembles embryonic stem cells in terms of morphology
and expression profiling, both mRNAs and microRNAs. Evidence supports both environmental factors and genetic predisposi-
tion underlying the development of TGCTs. Various models of development have been proposed and are discussed. In TGCTs,
gain of material from the short arm of chromosome 12 is invariable: genes from this region include the proto-oncogene KRAS,
which has activating mutations in �10% of tumors or is frequently overexpressed. A number of different approaches to
increase the understanding of the development and progression of TGCTs have highlighted the involvement of KIT, RAS/RAF/
MAPK, STAT, and PI3K/AKT signaling. We review the role of these signaling pathways in this process and the potential influ-
ence of environmental factors in the development of TGCTs. VVC 2008 Wiley-Liss, Inc.
INTRODUCTION
Testicular germ cell tumors of adults and adoles-
cents (TGCTs) are the most common tumor in
male Caucasian patients aged 15–34 years (Hor-
wich et al., 1991) and account for 60% of all male
malignancies between the ages 20–40 years
(Ulbright, 1993). It is a major cause of death in
these age groups, despite its overall curability.
TGCTs can be classified into two main histological
subtypes, seminoma (SE) and nonseminoma (NS).
SE resembles primordial germ cells (PGC) or early
gonocytes, the cells from which all TGCTs are
thought to be derived. NS exhibits various stages
of embryonic differentiation ranging from undiffer-
entiated cells (embryonal carcinoma, EC), which
resemble embryonic stem cells to the highly differ-
entiated cells of somatic tissue types in teratomas
(Mostofi, 1973). NS can also resemble extraem-
bryonic tissues namely yolk sac tumors and chorio-
carcinomas. In addition, TGCTs may present with
a mixture of seminomatous and nonseminomatous
elements. SE and the EC component of NS
express markers of pluripotency including OCT3/
4, STELLAR, and NANOG (Oosterhuis and Looi-
jenga, 2005). Expression profiling data has pro-
vided evidence for similarities between embryonic
stem cells and TGCTs, in particular the EC type
(Sperger et al., 2003). Recently, a similar observa-
tion was also found based on microRNAs expres-
sion profiling (Gillis et al., 2007; Looijenga et al.,
2007).
The most widely accepted model of TGCTs de-
velopment proposes an initial tumorigenic event in
utero and the development of a precursor lesion
known as intratubular germ cell neoplasia undiffer-
entiated (ITGCNU), also known as carcinoma in
situ (Skakkebaek, 1972). This is followed by a
period of dormancy until after puberty when
TGCTs emerge. This prepubertal dormancy sug-
gests that the TGCTs development is hormone
dependant, a factor which may differentiate the
pediatric and adult cases. However, recently
evidence has emerged to suggest potential mecha-
nisms for transformation of later cell types of the
spermatogenic lineage (discussed in detail later).
*Correspondence to: Janet Shipley, Molecular Cytogenetics,MUCRC, The Institute of Cancer Research, 15 Cotswold Rd,Sutton, Surrey, SM2 5NG, UK. E-mail: [email protected]
Received 19 September 2007; Accepted 18 February 2008
DOI 10.1002/gcc.20562
Published online 31 March 2008 inWiley InterScience (www.interscience.wiley.com).
VVC 2008 Wiley-Liss, Inc.
GENES, CHROMOSOMES & CANCER 47:547–557 (2008)
![Page 2: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/2.jpg)
Genetic aberrations in addition to the tetraploidy
found in ITGCNU are associated with progression
out of the seminiferous tubules and development
of invasive tumor.
Here, we review the impact that environmental
factors and genetic predisposition may have on
TGCTs development. We also consider the gene
products and pathways known to play a role in the
development of TGCTs and their progression from
ITGCNU. In particular, we draw comparisons
between the molecular biology and associated cel-
lular behavior of TGCTs and normal germ cell
development.
ENVIRONMENTAL FACTORS
Evidence of a role for environmental factors in
the etiology of TGCTs comes predominantly from
population migration studies. Sweden has an inci-
dence of TGCTs roughly twice that of Finland
(Parkin and Iscovich, 1997), and although first gen-
eration migrants from Finland to Sweden show no
increased risk (Ekbom et al., 2003), second genera-
tion males born to the migrant parents in Sweden
have a tendency to an increased frequency of
developing TGCTs (Montgomery et al., 2005). A
number of environmental factors have been inves-
tigated to explain the possible links with TGCTs-
development. Some evidence suggests association
of increased TGCTs risk and maternal smoking
during pregnancy, adult height, diet rich in cheese,
dizygotic twins, birth order, and sibship size
(Bonner et al., 2002; Dieckmann and Pichlmeier,
2002; Garner et al., 2003; Kaijser et al., 2003; Pet-
tersson et al., 2004; Richiardi et al., 2004a; Swer-
dlow et al., 1997), but underlying biological mecha-
nisms are unclear.
The strongest association of TGCTs exists with
disorders of genitourinary development including
cryptochidism or undescended testis (UDT), poor
sperm quality, and/or hypospodias (Mostofi, 1973;
Giwercman et al., 1988; Ondrus et al., 1997; Jacob-
sen et al., 2000). Collectively these disorders com-
prise a spectrum with TGCTs termed testicular
dysgenesis syndrome (TDS). This is increasingly
common and is proposed to be caused by genetic
and/or environmental influences (Skakkebaek
et al., 2001; Skakkebaek, 2002; Skakkebaek, 2003;
Skakkebaek et al., 2003). Hypothesized environ-
mental agents include pesticides (Garcia-Rodri-
guez et al., 1996) and nonsteroidal estrogens such
as diethylstilbestrol (DES) (Strohsnitter et al.,
2001). Increased levels of estrogen exposure in
utero have been proposed to increase the risk of
TDS and TGCTs (Weir et al., 2000; English et al.,
2003; Sharpe, 2003), and exposure of women to the
nonsteroidal estrogen DES during pregnancy
increases the risk of TGCTs (Strohsnitter et al.,
2001). In rats, administration of estradiol or ethinyl
estradiol (steroidal estrogens) during pregnancy
increases the rate of cryptorchidism and possibly
increases the risk of testicular teratoma (Lassur-
guere et al., 2003). Other studies however find no
role for high levels of natural estrogen increasing
TGCTs incidence, including two studies where
higher levels of estrogen were found in ethnic
groups with lower incidences of TGCT (Die-
ckmann et al., 2001; Hsieh et al., 2002; Zhang
et al., 2005).
GENETIC PREDISPOSITION
Familial predisposition to TGCTs, ethnic varia-
tions in incidence, and an association with certain
chromosome abnormality syndromes suggest that
inherited factors also play a role in disease develop-
ment. The familial predisposition seen in TGCTs
is one of the strongest for any tumor type. The
increased relative risk of TGCTs development
associated with fathers and sons of TGCTs patients
is fourfold, while between brothers it is higher at 8-
to 10-fold (Forman et al., 1992). Genome-wide
linkage analysis of affected families has thus far
provided evidence for two susceptibility loci, one
at Xq27 (which is possibly an indirect effect,
explained by being a susceptibility locus for unde-
scended testis (UDT which is part of TDS) and
another at 12q (Rapley et al., 2000; Rapley et al.,
2003). It is hypothesized that a genetic polymor-
phism at the Xq27 locus is responsible for the
genetic predisposition, although this remains to be
identified (Rapley et al., 2003). It is probable that
both genetic and shared environmental factors pro-
duce the high familial risk seen in TGCTs and that
the interplay between these two factors, along with
genetic heterogeneity, may make familial associ-
ated susceptibility loci difficult to determine.
TGCTs incidence varies among different racial
groups with the highest rates among Caucasian of
the USA and Western Europe and much lower
rates among Black Americans, Asians, Puerto
Ricans, and Africans (Waterhouse, 1985; Moul
et al., 1994; McGlynn et al., 2003). Variation in
incidence exists between countries in Europe
although this may either be due to racial or envi-
ronmental factors. Denmark has the highest inci-
dence of TGCTs, at 15.4 per 100,000, followed by
Norway and Sweden, whereas Lithuania has a
much lower incidence of 2.1 per 100,000 (Richiardi
et al., 2004b).
Genes, Chromosomes & Cancer DOI 10.1002/gcc
548 MCINTYRE ETAL.
![Page 3: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/3.jpg)
Down and Klinefelter syndromes are associated
with an extra chromosome 21 and X, respectively
and have been identified as predisposing factors to
SE and NS, although tumors in Klinefelter syn-
drome patients are not of the testis, but of the an-
terior mediastinum (Hasle et al., 1995; Satge et al.,
1997). Down syndrome males also have increased
incidence of UDT (Chew and Hutson, 2004). It is
likely that the increased risk of TGCTs may be
due to gene dosage effects of the chromosome 21
trisomy and/or hormonal disturbance (Satge et al.,
1997). In a study of Chinese patients with testicu-
lar dysgenesis and spermatocytic arrest, chromo-
some 21 aberrations were commonly found (Guo
et al., 2002), suggesting that genes within this chro-
mosome may be required for normal testicular and
gonocyte development and that overexpression of
these genes may result in testis malformation and/
or ITGCNU development. The incidence of
mediastinal germ cell tumors in males with Kline-
felter syndrome, which is associated with TDS, is
50 times greater than in the normal population
(Lanfranco et al., 2004; Aguirre et al., 2006).
MODELS OF TGCTs DEVELOPMENT
The generally accepted model of TGCTs devel-
opment proposes that PGC or gonocytes form the
precursor lesion ITGCNU in utero, which post-
puberty develops into either SE or NS (Fig. 1).
Evidence to support the development of ITGCNU
from PGC includes similarities in gene expression
profiles (Almstrup et al., 2004), telomerase activity
(Albanell et al., 1999), and patterns of genomic
imprinting (van Gurp et al., 1994; Kawakami et al.,
2006). The presence of ITGCNU has been
reported in aborted trisomy 21 fetuses in two case
reports, one at Week 18 and the second at Week 22
of gestation (Jacobsen and Henriques, 1992; Satge
et al., 1997). In addition, extragonadal tumors
(which represent 5% SE and NS) develop at sites
along the midline of the body namely the pineal
gland, mediastinum, and retroperitoneum (Hor-
Figure 1. Differential gene expression in the germ cell lineage. ESC, embryonal stem cell; PGC, primor-dial germ cell; GC, gonocyte; SSC, spermatogonial stem cell; 1SC, primary spermatocyte; 2SC, secondaryspermatocyte; CIS, carcinoma in situ (ITGCNU); SE, seminoma; EC, embryonal carcinoma; MT, mature ter-atoma; CC, choriocarcinoma; YS, yolk sac tumor. Bars indicate gene expressed documented, ‘‘?’’ denotesgene expression status unknown.
Genes, Chromosomes & Cancer DOI 10.1002/gcc
549TESTICULAR GERM CELL TUMOR DEVELOPMENT
![Page 4: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/4.jpg)
wich et al., 1991). ITGCNU has also been pro-
posed to develop from later stages of gonocyte de-
velopment at the zygotene-pachytene spermato-
cyte (Chaganti and Houldsworth, 2000). In addi-
tion, the recent discovery of a population of
pluripotent cells within mouse adult testis display-
ing features suggestive of a stem cell phenotype
(maGSCs) (Guan et al., 2006) raises the possibility
that TGCTs could arise from malignant transfor-
mation affecting this lineage.
Fifty percent of patients with ITGCNU develop
invasive lesions within 5 years of diagnosis (Ooster-
huis and Looijenga, 2005). Furthermore, it is pro-
posed that most if not all diagnosed ITGCNU pro-
gress to invasive tumor as ITGCNU frequency in
the population is equal to the frequency of TGCTs
(Linke et al., 2005). Molecular evidence support-
ing the development of invasive tumor from
ITGCNU includes conserved genetic lesions and
expression of histological markers. Shared genetic
aberrations include activating mutations of KIT(Looijenga et al., 2003) and gain of material from
12p, invariably found in the invasive component of
tumor and found in the adjacent ITGCNU from 8
of 29 samples examined (Looijenga et al., 2000;
Rosenberg et al., 2000; Summersgill et al., 2001;
Ottesen et al., 2003). Other genomic imbalances
frequently found in both the ITCGN and the inva-
sive tumor component using metaphase CGH
include gain of material from chromosomes 1, 5, 7,
and X, and loss of material from chromosome 18
(Summersgill et al., 2001). Histological markers
that can be expressed in both ITGCNU and the
invasive components include OCT3/4, placental
alkaline phosphatase, and KIT (Izquierdo et al.,
1995; Honecker et al., 2004).
Around 10% of TGCTs contain both SE and NS
(Mostofi, 1973) suggesting that ITGCNU may not
initially be subtype-specific. However, the associa-
tion of immunohistochemical markers in ITGCNU
with a particular histology suggests that the
ITGCNU may develop along pathways associated
more with a single subtype. Immunohistochemical
staining for a number of markers found differences
in the expression of antigens, particularly in
ITGCNU adjacent to combined tumors (SE and
NS elements) (Meyts et al., 1996). This study con-
cluded that ITGCNU is a phenotypically hetero-
geneous lesion and even adjacent cells may be at
different developmental stages (Meyts et al.,
1996). This might also be due to the plasticity of
the ITGCNU cells along the physiological germ
cell lineage. Other evidence that there is subtype-
specific development within ITGCNU includes
the association of chromosomal imbalances in the
ITGCNU and particular histologies. These in-
clude loss of material from chromosome 15 (NS
and ITGCNU adjacent to NS) and loss of hetero-
zygosity of 3q27–q28 (only ITGCNU adjacent to
EC) (Faulkner et al., 2000; Looijenga et al., 2000;
Summersgill et al., 2001; Ottesen et al., 2003).
It has also been suggested that the development
of TGCTs might follow a single pathway with pro-
gression from ITGCNU through SE to NS (Oliver,
1987; Oosterhuis et al., 1989). This might explain
the presence of NS elements reported in the me-
tastasis of pure SE primary tumors (Oliver, 1987)
but is inconsistent with the average age at develop-
ment of these tumors, with SE presenting 10 years
later than NS. Therefore, this linear progression
model is unlikely to apply to all NS (Oosterhuis
and Looijenga, 2005).
SE and NS form two distinct types of TGCTs.
EC represents NS at its most pluripotent stage,
with yolk sac, choriocarcinoma, or malignant tera-
tomatous elements arising from varying degrees
and paths of differentiation. These differences are
demonstrable at the level of gene expression (Juric
et al., 2005; Skotheim et al., 2005) and also micro-
RNA expression (Looijenga et al., 2007; Gillis
et al., 2007). MicroRNAs are short RNA molecules
that regulate gene expression and are associated
with processes including differentiation (Houbaviy
et al., 2003). SE express a number of pluripotency
genes (Skotheim et al., 2005) and EC are notable
for their similarity with embryonic stem cells
(Sperger et al., 2003). A cassette of these genes
located on chromosome 12 (NANOG, CD9, EDR1,SCNN1A, GDF3, Glut3, Stella) plus OCT3/4 on
chromosome 6 are repressed by retinoic acid,
resulting in loss of pluripotency (Giuliano et al.,
2005) and activation of homeobox genes (Mavilio
et al., 1988). OCT3/4 is an important controller of
this pluripotency, as demonstrated using siRNA
knockdown (Giuliano et al., 2005) and has been
linked with differentiation patterns early in
embryological development (Niwa et al., 2005).
Furthermore, phenotypic similarities between the
behavior of differentiating embryonic stem cells
and EC cells in culture correspond to karyotypic
changes common to both (Andrews et al., 2005).
A stage in tumor progression between ITGCNU
and overt TGCTs has been described, termed as
microinvasive germ cell tumor (MGCT). MGCT is
identified as a series of small groups or single
malignant germ cells in the peritubular interstitial
tissue and has a histological appearance similar to
that of SE whether associated with SE or NS.
Genes, Chromosomes & Cancer DOI 10.1002/gcc
550 MCINTYRE ETAL.
![Page 5: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/5.jpg)
MGCT is found in a smaller proportion of cases
than ITGCNU (9/106 SE and 32/149 NS samples)
(von Eyben et al., 2004). There are few studies
examining this stage and little is known about its
molecular biology, although it does stain positively
for PLAP and KIT even if associated with embry-
onal carcinoma (von Eyben et al., 2004).
MOLECULAR BIOLOGYOF ESTROGENS IN
ITGCNU FORMATION
Given the evidence that TGCTs develop from
ITGCNU it can be assumed that factors that
increase the likelihood of developing TGCTs must
assert this effect by increasing the likelihood of
developing ITGCNU. Estrogens are a proposed
etiological factor in TGCTs development.
Research in the mouse has determined that estro-
gens stimulate PGC proliferation. This occurs
through the somatic cells of the testis, which in
response to the estrogen stimulation upregulate
stem cell factor (SCF) expression and secretion
leading to activation of the AKTsignaling pathway
in the PGC. This research also showed that expo-
sure to high levels of estrogen in conjunction with
factors that inhibit PGC differentiation (such as
leukemia inhibitory factor) can result in oncogenic
transformation of PGC; however, no ITGCNU or
SE was observed (Moe-Behrens et al., 2003). This
provides evidence of a molecular mechanism
whereby increased levels of estrogen during testic-
ular development can lead to TGCTs. This work
also determined that estrogen acts through
increased activation of KIT signaling through AKT
(Moe-Behrens et al., 2003). In addition, activating
mutations of KIT have been determined in
ITGCNU (Looijenga et al., 2003). This evidence
suggests that KIT activation may play a role in
ITGCNU development, but also requires other
factors in transformation of the PGC. Research has
determined activation of KIT, along with other fac-
tors, to be important in both proliferation and sur-
vival of PGC (De Miguel et al., 2002). Physiologi-
cally, KIT plays a key role in PGC proliferation (Li
et al., 2003), survival (De Felici, 2000), and migra-
tion where SCF, the ligand for KIT, is localized to
the membranes of somatic cells associated with the
PGC migratory pathway (Kierszenbaum and Tres,
2001). Only a few studies have examined the rela-
tionship between estrogen stimulation, KIT signal-
ing pathway activation, and the phenotypic effects
of this in PGC. Further work is required to fully
understand any role for these in transformation of
PGC. Investigations have also highlighted the im-
portance of AKTactivation in maintaining pluripo-
tency (Armstrong et al., 2006; Watanabe et al.,
2006), suggesting this signaling may have a role in
inhibiting the differentiation process of normal
PGC development. Further evidence for this
comes from in vivo and in vitro experiments with
mouse PGCs which lacked PTEN, a negative reg-
ulator of AKT activation. The PTEN-null PGCs
exhibited significant effects on the differentiation
state of germ cell lineage and the authors con-
cluded that PTEN appeared to be essential for
germ cell differentiation (Kimura et al., 2003).
KITAND RAS SIGNALING IN TGCTs
A number of investigations in PGC have high-
lighted the importance of signaling molecules
downstream of KIT and RAS in the phenotype of
these cells. In addition, some of these have been
investigated in cell lines providing further evi-
dence that these signaling pathways are of impor-
tance in TGCTs development. An overview of the
signaling interactions of these proteins within the
KIT and RAS signaling pathways can be seen in
Figure 2.
Specific amplification, overexpression, and mu-
tation of KIT have been reported in SE. These
changes are predominantly associated with SE,
however a small number of KIT-activating muta-
tions have been found in NS generally associated
with bilateral tumors (Looijenga et al., 2003;
Kemmer et al., 2004; McIntyre et al., 2004; Rapley
et al., 2004; McIntyre et al., 2005a; Willmore-Payne
et al., 2005). KIT expression is also predominantly
associated with SE but is also found in �30% of
NS where the staining is restricted to the cyto-
plasm unlike the SE which also show membranous
staining (Izquierdo et al., 1995). Significantly
experiments inhibiting KIT expression in the SE
cell line TCam-2 using siRNA resulted in a reduc-
tion in the number of viable cells over a time
course (Goddard et al., 2007). Activating mutation,
amplification, and overexpression of KRAS, whichsignals downstream of KIT, are also found in
TGCTs (Olie et al., 1995; McIntyre et al., 2005b).
Interestingly, activated KRAS resulted in and
increased in vitro survival of SE cells, which was
also found for the presence of a restricted 12p-
amplification (Roelofs et al., 2000). Both RAS and
KIT activate a number of signaling molecules
including PI3-kinase (PI3K). Activated RAS binds
directly to and activates the p110 catalytic subunit
of PI3K (Marte and Downward, 1997; Cox and
Der, 2003; Downward, 2003; Campbell and Der,
2004). Similarly upon stimulation, KIT activates
the p85 subunit of PI3kinase either through direct
Genes, Chromosomes & Cancer DOI 10.1002/gcc
551TESTICULAR GERM CELL TUMOR DEVELOPMENT
![Page 6: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/6.jpg)
interaction or through the signaling mediator Src
(Hong et al., 2004).
The tumor suppressor PTEN inhibits PI3K ac-
tivity. In PGC, upregulation of PTEN phosphoryl-
ation (resulting in deactivation of the protein) was
determined upon stimulation with SCF or estro-
gen. This work also demonstrated that reduction in
PTEN activity increased growth and sensitivity to
transformation of PGC upon the addition of growth
factors including SCF (Moe-Behrens et al., 2003).
Male mice with an engineered PGC-specific dele-
tion of PTEN develop bilateral testicular teratoma
(Kimura et al., 2003). That this occurred with early
onset implies it is unlikely that any additional
genetic alterations were required for the tumor for-
mation. This study also determined that PTEN
was important in differentiation of PGC to form
mature germ cells (Kimura et al., 2003). A study of
PTEN in five TGCTs cell lines revealed three with
LOH and one harboring a PTEN missense muta-
tion (Teng et al., 1997). PTEN loss has also been
implicated in the progression from ITGCNU to
invasive disease, with investigators finding loss/
decreased expression of PTEN in 56% SE and
86% NS. LOH and inactivating mutations of
PTEN were found at frequencies of 36 and 9%,
respectively (Di Vizio et al., 2005). In addition in-
hibition of PI3K, using wortmannin, reduced inva-
sive migration in an embryonal carcinoma cell line
(Diez-Torre et al., 2004).
Activation of PI3K results in its translocation to
the membrane and activation through secondary
messengers of a number of proteins including
AKT. AKT is therefore activated upon activation
of RAS and/or KIT (Marte and Downward, 1997;
Cox and Der, 2003; Downward, 2003; Campbell
and Der, 2004). Moe-Behrens et al. (2003) deter-
mined upregulation of AKT phosphorylation upon
stimulation with SCF or estrogens (which induced
upregulation of SCF secretion by the somatic cells
Figure 2. A model of RAS signaling in TGCTs. Striped moleculesdenote proteins for which aberrant expression or aberrant expressioncopy number and/or mutation of the gene that encodes the protein hasbeen observed in studies of TGCTs. This diagram was constructed withinformation from: Campbell and Der, 2004; Cox and Der, 2003; Di Vizioet al., 2005; Downward, 2003; Downward, 2004; Han et al., 2001; Hong
et al., 2004; Houldsworth et al., 1997; Houldsworth et al., 1998; Kamaiet al., 2002; Kemmer et al., 2004; Leaman et al., 1996; Li et al., 2003;Marte and Downward, 1997; McIntyre et al., 2005a; Miyagi et al., 2004;Murty and Chaganti, 1998; Ronnstrand, 2004; Sommerer et al., 2005;Teng et al., 1997; Wennerberg et al., 2005; Ye et al., 1993; Yu et al.,2005.
Genes, Chromosomes & Cancer DOI 10.1002/gcc
552 MCINTYRE ETAL.
![Page 7: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/7.jpg)
of the testis) in PGC. This increase in AKTactiva-
tion was inhibited with the PI3K inhibitor
LY294002 (Moe-Behrens et al., 2003) (Fig. 2).
Overexpression of AKT dramatically increased
PGC growth in another study (De Miguel et al.,
2002).
A high level of (activated) phospho-AKT was
found in the majority of both NS and SE. How-
ever, no difference in AKT activation was deter-
mined between samples with or without KIT acti-
vating mutations suggesting that activation may be
achieved through other mechanisms. These could
include the functional loss of PTEN as described
earlier (Kemmer et al., 2004; Sommerer et al.,
2005). Activated AKT inhibits proapoptotic pro-
teins including BAD and, through its phosphoryl-
ating interactions with MDM2, inhibits P53 tran-
scriptional promotion of additional proapoptotic
genes including BAX (Downward, 2004). BAX is
required for both differentiation and apoptosis in
PGC (Stallock et al., 2003) and is upregulated in
PGC undergoing apoptosis in culture. Addition of
SCF inhibited an increase in BAX protein levels in
PGC in response to proapoptotic stimuli (Felici
et al., 1999). In TGCTs, the level of BAX protein
was reduced in a cisplatin-resistant cell line com-
pared to levels in a cisplatin-sensitive cell line
(Houldsworth et al., 1998).
RAS activation also upregulates the MAPK sig-
naling cascade, directly binding the RAF kinases.
Activating mutations of BRAF were found in 9% of
NS where they were restricted to the embryonal
carcinoma components (Sommerer et al., 2005).
However, another study which did not examine
the different components of the NS separately
found no BRAF mutations in 32 SE, 27 NS, and
6 combined tumors (McIntyre et al., 2005b).
Recently, an activating mutation has also been
found in the SE cell line TCam-2 (de Jong et al.,
2008). The interaction with activated RAS induces
the relocation of RAF to the plasma membrane
where it becomes phosphorylated by additional
factors, activating the downstream signaling cas-
cade. Activation of this cascade results in activation
of transcription factors which upregulate transcrip-
tion of genes (such as cyclinD1) promoting migra-
tion and proliferation (Marte and Downward, 1997;
Cox and Der, 2003; Downward, 2003; Campbell
and Der 2004; Yu et al., 2005). Inhibitors of MAPK
signaling reduce PGC numbers suggesting that the
MAPK signaling pathway is involved in promoting
survival and proliferation (De Miguel et al., 2002).
High levels of activated ERK (part of the MAPK
signaling cascade) were found in the majority of
both NS and SE (Kemmer et al., 2004; Sommerer
et al., 2005).
KIT is also known to activate members of the
STAT family of proteins, including STAT-3, -5A,
and -5B (Leaman et al., 1996; Ronnstrand, 2004).
Upon activation, STATs dimerize and translocate
to the nucleus where they regulate gene expres-
sion. STAT signaling is important for both migra-
tion and proliferation in PGC (Li et al., 2003).
High levels of activated STAT3 were found in
most NS and SE (Kemmer et al., 2004; Sommerer
et al., 2005). Experiments in zebrafish have sug-
gested that STAT-3 activates RhoA kinase signal-
ing (Miyagi et al., 2004), also activated by RAS in a
PI3K-dependent manner (Downward 2003; Wen-
nerberg et al., 2005). RhoA and Rho-kinase have
been reported to be overexpressed in TGCTs
(Kamai et al., 2002).
A number of additional growth factor receptors
have been investigated in TGCT. These, like
KIT, also have the ability to activate the down-
stream signaling pathways discussed here. Alterna-
tive splicing and alternative promoter use of
PDGFRA, which encodes a protein structurally
related to KIT, was identified in TGCT. This gives
rise to a 1.5-kb transcript which is a highly selec-
tive marker for TGCT and ITGCNU (Mosselman
et al., 1996). PDGFRA is adjacent to KIT on chro-
mosome 4 but is not part of the minimum region of
amplification of this imbalance (McIntyre et al.,
2005a). EGFR expression was found to correspond
to the b-HCG component of TGCT, associated
with choriocarcinoma, by immunohistochemistry.
However, only 27% of positive cases had activated
phosphorylation of EGFR (Moroni et al., 2001).
ERBB2 expression was detected in 24% of NS by
immunohistochemistry where positive staining was
associated with the teratoma and choriocarcinoma
components of the tumors and was significantly
correlated with both stage and adverse clinical out-
come (Mandoky et al., 2004). Another study found
consistent results with increased expression of
ERBB2 in NS of differentiated histology excised
from the lymph nodes of patients postchemother-
apy (McIntyre et al., 2005b).
In addition to receptors, a number of growth fac-
tors have also been investigated, of these possibly
the most interesting is VEGF. VEGF expression is
associated with angiogenesis and metastasis in
TGCTas shown at both the RNA and protein lev-
els (Viglietto et al., 1996, Fukuda et al., 1999).
Analysis of the expression of VEGF identified
predominant expression of the VEGF121 and
VEGF165 isoforms which are highly active in
Genes, Chromosomes & Cancer DOI 10.1002/gcc
553TESTICULAR GERM CELL TUMOR DEVELOPMENT
![Page 8: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/8.jpg)
inducing vascularization as they are more effi-
ciently secreted. Thus it is proposed that VEGF
induces angiogenesis in a paracrine manner in
these tumors (Viglietto et al., 1996). Further to
VEGF, a number of other growth factors have been
identified to have increased expression levels,
these include Pleotrophin and FGF2 which
showed increased levels of roughly 20- and 7-fold,
respectively, in the serum of TGCT patients, both
SE and NS, compared to controls. Similarly EGF
showed increased levels but to a lesser extent
(Aigner et al., 2003). The expression of FGF4
(HST-1) in TGCT conversely to KIT was associ-
ated more with NS where it also correlated with tu-
mor stage (Strohmeyer et al., 1991). FGF4 has
more recently been shown to act as a survival factor
in germ cells reducing apoptotic death in mice tes-
tis when exposed to mild hypothermia where
FGF4 increased MAPK activation (Hirai et al.,
2004). The teratocarcinoma-derived growth factor-
1 (TDGF-1), which is structurally related to the
EGF family of growth factors was overexpressed in
100% of NS and 31% SE compared to normal tes-
tis. The authors hypothesized TDGF-1 may act as
an autocrine growth factor as functional work
showed exogeneous TDGF-1 induced prolifera-
tion of the NT2/D1 TGCT cell line (Baldassarre
et al., 1997).
Taken as a whole, this evidence suggests that in
TGCTs the upregulation of RAS signaling is im-
portant and that in SE, KIT signaling pathways are
important in TGCTs, promoting the survival, inva-
sive migration, and proliferative phenoptype of
these cells. Furthermore, results indicate that this
is achieved through reactivation of signaling impor-
tant in maintaining the same phenotype in the de-
velopment of PGC, the precursor cells for this tu-
mor type. The implication of KIT and RAS signal-
ing in TGCTs and further unraveling of the
downstream pathways involved should provide
potential therapeutic targets (Pero et al., 2002;
Downward, 2003; Pero et al., 2004; Ross et al.,
2004).
CONCLUDING COMMENTS
It is clear that both environmental and genetic
factors play an important role in the development
of TGCTs. Current models propose these factors
cause the deregulation of the normal differentia-
tion processes of PGC and development of the tes-
tis in utero. Little light has been shed on the
development of the tumors at this stage. Aside
from the invariable gain of material from 12p, only
a few consistent copy number imbalances and asso-
ciated genes, such as amplification of KIT (McIn-
tyre et al., 2005a), have been identified and investi-
gated. Recent analysis supports DNA copy number
having a major impact on the gene expression lev-
els in TGCTs (Almstrup et al., 2005; McIntyre
et al., 2007). Evidence indicates that RAS and KIT
signaling play a role in the tumor phenotype in
common with PGC. Recapitulation or maintenance
of signaling molecules and pathways important in
PGC appear to be involved in TGCTs develop-
ment. Therefore, future studies of both PGCs and
TGCTs will complement our understanding of
both. More functional-based studies using RNAi-
based technologies and small molecular inhibitors
of the molecules and pathways discussed will fur-
ther increase our understanding of the role of this
signaling in TGCT. In addition, work using model
organisms further examining deregulation of these
signaling pathways in PGCs will enhance our com-
prehension of their role in tumor initiation.
REFERENCES
Aguirre D, Nieto K, Lazos M, Pena YR, Palma I, Kofman-Alfaro S,Queipo G. 2006. Extragonadal germ cell tumors are often associ-ated with Klinefelter syndrome. Hum Pathol 37:477–480.
Aigner A, Brachmann P, Beyer J, Jager R, Raulais D, Vigny M, Neu-bauer A, Heidenreich A, Weinknecht S, Czubayko F, ZugmaierG. 2003. Marked increase of the growth factors pleiotrophin andfibroblast growth factor-2 in serum of testicular cancer patients.Ann Oncol 14:1525–1529.
Albanell J, Bosl GJ, Reuter VE, Engelhardt M, Franco S, MooreMA, Dmitrovsky E. 1999. Telomerase activity in germ cell can-cers and mature teratomas. J Natl Cancer Inst 91:1321–1326.
Almstrup K, Hoei-Hansen CE, Wirkner U, Blake J, Schwager C,Ansorge W, Nielsen JE, Skakkebaek NE, Rajpert-De Meyts E,Leffers H. 2004. Embryonic stem cell-like features of testicularcarcinoma in situ revealed by genome-wide gene expressionprofiling. Cancer Res 64:4736–4743.
Almstrup K, Hoei-Hansen CE, Nielsen JE, Wirkner U, Ansorge W,Skakkebaek NE, Rajpert-De Meyts E, Leffers H. 2005.Genome-wide gene expression profiling of testicular carcinoma insitu progression into overt tumors. Br J Cancer 92:1934–1941.
Andrews PW, Matin MM, Bahrami AR, Damjanov I, Gokhale P,Draper JS. 2005. Embryonic stem (ES) cells and embryonal carci-noma (EC) cells: Opposite sides of the same coin. Biochem SocTrans 33:1526–1530.
Armstrong L, Hughes O, Yung S, Hyslop L, Stewart R, Wappler I,Peters H, Walter T, Stojkovic P, Evans J, Stojkovic M, Lako M.2006. The role of PI3K/AKT, MAPK/ERK and NFkappabeta sig-nalling in the maintenance of human embryonic stem cell pluri-potency and viability highlighted by transcriptional profiling andfunctional analysis. Hum Mol Genet 15:1894–1913.
Baldassarre G, Romano A, Armenante F, Rambaldi M, Paoletti I,Sandomenico C, Pepe S, Staibano S, Salvatore G, De Rosa G, Per-sico MG, Viglietto G. 1997. Expression of teratocarcinoma-derived growth factor-1 (TDGF-1) in testis germ cell tumors andits effects on growth and differentiation of embryonal carcinomacell line NTERA2/D1. Oncogene 15:927–936.
Bonner MR, McCann SE, Moysich KB. 2002. Dietary factors andthe risk of testicular cancer. Nutr Cancer 44:35–43.
Campbell PM, Der CJ. 2004. Oncogenic Ras and its role in tumorcell invasion and metastasis. Semin Cancer Biol 14:105–114.
Chaganti RS, Houldsworth J. 2000. Genetics and biology of adulthuman male germ cell tumors. Cancer Res 60:1475–1482.
Chew G, Hutson JM. 2004. Incidence of cryptorchidism and ascend-ing testes in trisomy 21: A 10 year retrospective review. PediatrSurg Int 20:744–747.
Genes, Chromosomes & Cancer DOI 10.1002/gcc
554 MCINTYRE ETAL.
![Page 9: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/9.jpg)
Cox AD, Der CJ. 2003. The dark side of Ras: Regulation of apopto-sis. Oncogene 22:8999–9006.
De Felici M. 2000. Regulation of primordial germ cell developmentin the mouse. Int J Dev Biol 44:575–580.
de Jong J, Stoop H, Gillis AJ, Hersmus R, van Gurp RJ, van deGeijn GJ, van Drunen E, Beverloo HB, Schneider DT, SherlockJK, Baeten J, Kitazawa S, van Zoelen EJ, van Roozendaal K, Oos-terhuis JW, Looijenga LH. 2008. Further characterization of thefirst seminoma cell line TCam-2. Genes Chromosomes Cancer47:185–196.
De Miguel MP, Cheng L, Holland EC, Federspiel MJ, Donovan PJ.2002. Dissection of the c-Kit signaling pathway in mouse primor-dial germ cells by retroviral-mediated gene transfer. Proc NatlAcad Sci USA 99:10458–10463.
Di Vizio D, Cito L, Boccia A, Chieffi P, Insabato L, Pettinato G,Motti ML, Schepis F, D’Amico W, Fabiani F, Tavernise B, VenutaS, Fusco A, Viglietto G. 2005. Loss of the tumor suppressor genePTEN marks the transition from intratubular germ cell neoplasias(ITGCN) to invasive germ cell tumors. Oncogene 24:1882–1894.
Dieckmann KP, Endsin G, Pichlmeier U. 2001. How valid is theprenatal estrogen excess hypothesis of testicular germ cell cancer?A case control study on hormone-related factors. Eur Urol 40:677–683; discussion 684.
Dieckmann KP, Pichlmeier U. 2002. Is risk of testicular cancerrelated to body size? Eur Urol 42:564–569.
Diez-Torre A, Silvan U, De Wever O, Bruyneel E, Mareel M, Are-chaga J. 2004. Germinal tumor invasion and the role of the testic-ular stroma. Int J Dev Biol 48:545–557.
Downward J. 2003. Targeting RAS signalling pathways in cancertherapy. Nat Rev Cancer 3:11–22.
Downward J. 2004. PI 3-kinase, Akt and cell survival. Semin CellDev Biol 15:177–182.
Ekbom A, Richiardi L, Akre O, Montgomery SM, Sparen P. 2003.Age at immigration and duration of stay in relation to risk fortesticular cancer among Finnish immigrants in Sweden. J NatlCancer Inst 95:1238–1240.
English PB, Goldberg DE, Wolff C, Smith D. 2003. Parental andbirth characteristics in relation to testicular cancer risk amongmales born between 1960 and 1995 in California (United States).Cancer Causes Control 14:815–825.
Faulkner SW, Leigh DA, Oosterhuis JW, Roelofs H, Looijenga LH,Friedlander ML. 2000. Allelic losses in carcinoma in situ and tes-ticular germ cell tumors of adolescents and adults: Evidence sug-gestive of the linear progression model. Br J Cancer 83:729–736.
Felici MD, Carlo AD, Pesce M, Iona S, Farrace MG, Piacentini M.1999. Bcl-2 and Bax regulation of apoptosis in germ cells duringprenatal oogenesis in the mouse embryo. Cell Death Differ6:908–915.
Forman D, Oliver RT, Brett AR, Marsh SG, Moses JH, Bodmer JG,Chilvers CE, Pike MC. 1992. Familial testicular cancer: A reportof the UK family register, estimation of risk and an HLA class 1sib-pair analysis. Br J Cancer 65:255–262.
Fukuda S, Shirahama T, Imazono Y, Tsushima T, Ohmori H, Kaya-jima T, Take S, Nishiyama K, Yonezawa S, Akiba S, Akiyama S,Ohi Y. 1999. Expression of vascular endothelial growth factor inpatients with testicular germ cell tumors as an indicator of meta-static disease. Cancer 85:1323–1330.
Garcia-Rodriguez J, Garcia-Martin M, Nogueras-Ocana M, de DiosLuna-del-Castillo J, Espigares Garcia M, Olea N, Lardelli-ClaretP. 1996. Exposure to pesticides and cryptorchidism: Geographicalevidence of a possible association. Environ Health Perspect104:1090–1095.
Garner MJ, Birkett NJ, Johnson KC, Shatenstein B, Ghadirian P,Krewski D. 2003. Dietary risk factors for testicular carcinoma. IntJ Cancer 106:934–941.
Gillis AJ, Stoop HJ, Hersmus R, Oosterhuis JW, Sun Y, Chen C,Guenther S, Sherlock J, Veltman I, Baeten J, van der Spek PJ, deAlarcon P, Looijenga LH. 2007. High-throughput microRNAomeanalysis in human germ cell tumours. J Pathol 213:319–328.
Giuliano CJ, Kerley-Hamilton JS, Bee T, Freemantle SJ, Manickar-atnam R, Dmitrovsky E, Spinella MJ. 2005. Retinoic acidrepresses a cassette of candidate pluripotency chromosome 12pgenes during induced loss of human embryonal carcinoma tumori-genicity. Biochim Biophys Acta 1731:48–56.
Giwercman A, Muller J, Skakkeboek NE. 1988. Cryptorchidism andtesticular neoplasia. Horm Res 30:157–163.
Goddard NC, McIntyre A, Summersgill B, Gilbert D, Kitazawa S,Shipley J. 2007. KIT and RAS signalling pathways in testiculargerm cell tumours: New data and a review of the literature. Int JAndrol 30:337–348; discussion 349.
Guan K, Nayernia K, Maier LS, Wagner S, Dressel R, Lee JH,Nolte J, Wolf F, Li M, Engel W, Hasenfuss G. 2006. Pluripotencyof spermatogonial stem cells from adult mouse testis. Nature440:1199–1203.
Guo JH, Zhu PY, Huang YF, Yu L. 2002. Autosomal aberrations asso-ciated with testicular dysgenesis or spermatogenic arrest inChinese patients. Asian J Androl 4:3–7.
Han DC, Shen TL, Guan JL. 2001. The Grb7 family proteins:Structure, interactions with other signaling molecules and poten-tial cellular functions. Oncogene 20:6315–6321.
Hasle H, Mellemgaard A, Nielsen J, Hansen J. 1995. Cancer inci-dence in men with Klinefelter syndrome. Br J Cancer 71:416–420.
Hirai K, Sasaki H, Yamamoto H, Sakamoto H, Kubota Y, Kakizoe T,Terada M, Ochiya T. 2004. HST-1/FGF-4 protects male germcells from apoptosis under heat-stress condition. Exp Cell Res294:77–85.
Honecker F, Stoop H, de Krijger RR, Chris Lau YF, Bokemeyer C,Looijenga LH. 2004. Pathobiological implications of the expres-sion of markers of testicular carcinoma in situ by fetal germ cells.J Pathol 203:849–857.
Hong L, Munugalavadla V, Kapur R. 2004. c-Kit-mediated overlap-ping and unique functional and biochemical outcomes via diversesignaling pathways. Mol Cell Biol 24:1401–1410.
Horwich A, Dearnaley DP, Nicholls J, Jay G, Mason M, Harland S,Peckham MJ, Hendry WF. 1991. Effectiveness of carboplatin,etoposide, and bleomycin combination chemotherapy in good-prognosis metastatic testicular nonseminomatous germ celltumors. J Clin Oncol 9:62–69.
Houbaviy HB, Murray MF, Sharp PA. 2003. Embryonic stem cell-specific MicroRNAs. Dev Cell 5:351–358.
Houldsworth J, Reuter V, Bosl GJ, Chaganti RS. 1997. Aberrantexpression of cyclin D2 is an early event in human male germ celltumorigenesis. Cell Growth Differ 8:293–299.
Houldsworth J, Xiao H, Murty VV, Chen W, Ray B, Reuter VE, BoslGJ, Chaganti RS. 1998. Human male germ cell tumor resistanceto cisplatin is linked to TP53 gene mutation. Oncogene 16:2345–2349.
Hsieh CC, Lambe M, Trichopoulos D, Ekbom A, Akre O, AdamiHO. 2002. Early life exposure to oestrogen and testicular cancerrisk: Evidence against an aetiological hypothesis. Br J Cancer86:1363–1364.
Izquierdo MA, Van der Valk P, Van Ark-Otte J, Rubio G, Germa-Lluch JR, Ueda R, Scheper RJ, Takahashi T, Giaccone G. 1995.Differential expression of the c-kit proto-oncogene in germ celltumors. J Pathol 177:253–258.
Jacobsen GK, Henriques UV. 1992. A fetal testis with intratubulargerm cell neoplasia (ITGCN). Mod Pathol 5:547–549.
Jacobsen R, Bostofte E, Engholm G, Hansen J, Olsen JH, Skakke-baek NE, Moller H. 2000. Risk of testicular cancer in men withabnormal semen characteristics: Cohort study. Bmj 321:789–792.
Juric D, Sale S, Hromas RA, Yu R, Wang Y, Duran GE, TibshiraniR, Einhorn LH, Sikic BI. 2005. Gene expression profiling differ-entiates germ cell tumors from other cancers and defines subtype-specific signatures. Proc Natl Acad Sci USA 102:17763–17768.
Kaijser M, Akre O, Cnattingius S, Ekbom A. 2003. Maternal lungcancer and testicular cancer risk in the offspring. Cancer Epide-miol Biomark Prev 12:643–646.
Kamai T, Arai K, Sumi S, Tsujii T, Honda M, Yamanishi T, YoshidaKI. 2002. The rho/rho-kinase pathway is involved in the progres-sion of testicular germ cell tumor. BJU Int 89:449–453.
Kawakami T, Zhang C, Okada Y, Okamoto K. 2006. Erasure ofmethylation imprint at the promoter and CTCF-binding siteupstream of H19 in human testicular germ cell tumors of adoles-cents indicate their fetal germ cell origin. Oncogene 25:3225–3236.
Kemmer K, Corless CL, Fletcher JA, McGreevey L, Haley A, Grif-fith D, Cummings OW, Wait C, Town A, Heinrich MC. 2004.KIT mutations are common in testicular seminomas. Am J Pathol164:305–313.
Kierszenbaum AL, Tres LL. 2001. Primordial germ cell-somatic cellpartnership: A balancing cell signaling act. Mol Reprod Dev60:277–280.
Kimura T, Suzuki A, Fujita Y, Yomogida K, Lomeli H, Asada N,Ikeuchi M, Nagy A, Mak TW, Nakano T. 2003. Conditional lossof PTEN leads to testicular teratoma and enhances embryonicgerm cell production. Development 130:1691–1700.
Lanfranco F, Kamischke A, Zitzmann M, Nieschlag E. 2004. Kline-felter’s syndrome. Lancet 364:273–283.
Lassurguere J, Livera G, Habert R, Jegou B. 2003. Time- And dose-related effects of estradiol and diethylstilbestrol on the morphol-
Genes, Chromosomes & Cancer DOI 10.1002/gcc
555TESTICULAR GERM CELL TUMOR DEVELOPMENT
![Page 10: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/10.jpg)
ogy and function of the fetal rat testis in culture. Toxicol Sci73:160–169.
Leaman DW, Leung S, Li X, Stark GR. 1996. Regulation of STAT-dependent pathways by growth factors and cytokines. FASEB J10:1578–1588.
Li J, Xia F, Li WX. 2003. Coactivation of STATand Ras is requiredfor germ cell proliferation and invasive migration in Drosophila.Dev Cell 5:787–798.
Linke J, Loy V, Dieckmann KP. 2005. Prevalence of testicular intra-epithelial neoplasia in healthy males. J Urol 173:1577–1579.
Looijenga LH, de Leeuw H, van Oorschot M, van Gurp RJ, StoopH, Gillis AJ, de Gouveia Brazao CA, Weber RF, Kirkels WJ, vanDijk T, von Lindern M, Valk P, Lajos G, Olah E, Nesland JM,FossA SD, Oosterhuis JW. 2003. Stem cell factor receptor (c-KIT)codon 816 mutations predict development of bilateral testiculargerm-cell tumors. Cancer Res 63:7674–7678.
Looijenga LH, Rosenberg C, van Gurp RJ, Geelen E, van Echten-Arends J, de Jong B, Mostert M, Wolter Oosterhuis J. 2000. Com-parative genomic hybridization of microdissected samples fromdifferent stages in the development of a seminoma and a non-seminoma. J Pathol 191:187–192.
Looijenga LH, Gillis AJ, Stoop H, Hersmus R, Oosterhuis JW. 2007.Relevance of microRNAs in normal and malignant development,including human testicular germ cell tumors. Int J Androl 30:304–314
Mandoky L, Geczi L, Bodrogi I, Toth J, Csuka O, Kasler M, Bak M.2004. Clinical relevance of HER-2/neu expression in germ-celltesticular tumors. Anticancer Res 24:2219–2224.
Marte BM, Downward J. 1997. PKB/Akt: Connecting phosphoinosi-tide 3-kinase to cell survival and beyond. Trends Biochem Sci22:355–358.
Mavilio F, Simeone A, Boncinelli E, Andrews PW. 1988. Activationof four homeobox gene clusters in human embryonal carcinomacells induced to differentiate by retinoic acid. Differentiation37:73–79.
McGlynn KA, Devesa SS, Sigurdson AJ, Brown LM, Tsao L, TaroneRE. 2003. Trends in the incidence of testicular germ cell tumorsin the United States. Cancer 97:63–70.
McIntyre A, Summersgill B, Grygalewicz B, Gillis AJ, Stoop J, vanGurp RJ, Dennis N, Fisher C, Huddart R, Cooper C, Clark J,Oosterhuis JW, Looijenga LH, Shipley J. 2005a. Amplificationand overexpression of the KIT gene is associated with progressionin the seminoma subtype of testicular germ cell tumors of adoles-cents and adults. Cancer Res 65:8085–8089.
McIntyre A, Summersgill B, Jafer O, Rodriguez S, Zafarana G, Oos-terhuis JW, Gillis AJ, Looijenga L, Cooper C, Huddart R, Clark J,Shipley J. 2004. Defining minimum genomic regions of imbalanceinvolved in testicular germ cell tumors of adolescents and adultsthrough genome wide microarray analysis of cDNA clones. Onco-gene 23:9142–9147.
McIntyre A, Summersgill B, Spendlove HE, Huddart R, HoulstonR, Shipley J. 2005b. Activating mutations and/or expression levelsof tyrosine kinase receptors GRB7, RAS, and BRAF in testiculargerm cell tumors. Neoplasia 7:1047–1052.
McIntyre A, Summersgill B, Lu YJ, Missiaglia E, Kitazawa S, Oos-terhuis JW, Looijenga LH, Shipley J. 2007. Genomic copy num-ber and expression patterns in testicular germ cell tumours. Br JCancer 97:1707–1712.
Meyts ER, Jorgensen N, Muller J, Skakkebaek NE. 1996. Pro-longed expression of the c-kit receptor in germ cells of intersexfetal testes. J Pathol 178:166–169.
Miyagi C, Yamashita S, Ohba Y, Yoshizaki H, Matsuda M, Hirano T.2004. STAT3 noncell-autonomously controls planar cell polarityduring zebrafish convergence and extension. J Cell Biol 166:975–981.
Moe-Behrens GH, Klinger FG, Eskild W, Grotmol T, Haugen TB,De Felici M. 2003. Akt/PTEN signaling mediates estrogen-dependent proliferation of primordial germ cells in vitro. MolEndocrinol 17:2630–2638.
Montgomery SM, Granath F, Ehlin A, Sparen P, Ekbom A. 2005.Germ-cell testicular cancer in offspring of Finnish immigrants toSweden. Cancer Epidemiol Biomark Prev 14:280–282.
Moroni M, Veronese S, Schiavo R, Carminati O, Sorensen BS, Gam-bacorta M, Siena S. 2001. Epidermal growth factor receptorexpression and activation in nonseminomatous germ cell tumors.Clin Cancer Res 7:2770–2775.
Mosselman S, Looijenga LH, Gillis AJ, van Rooijen MA, Kraft HJ,van Zoelen EJ, Oosterhuis JW. 1996. Aberrant platelet-derivedgrowth factor alpha-receptor transcript as a diagnostic marker for
early human germ cell tumors of the adult testis. Proc Natl AcadSci USA 93:2884–2888.
Mostofi FK. 1973. Proceedings: Testicular tumors. Epidemiologic,etiologic, and pathologic features. Cancer 32:1186–1201.
Moul JW, Schanne FJ, Thompson IM, Frazier HA, Peretsman SA,Wettlaufer JN, Rozanski TA, Stack RS, Kreder KJ, Hoffman KJ.1994. Testicular cancer in blacks. A multicenter experience.Cancer 73:388–393.
Murty VV, Chaganti RS. 1998. A genetic perspective of male germcell tumors. Semin Oncol 25:133–144.
Niwa H, Toyooka Y, Shimosato D, Strumpf D, Takahashi K, Yagi R,Rossant J. 2005. Interaction between Oct3/4 and Cdx2 determinestrophectoderm differentiation. Cell 123:917–929.
Olie RA, Looijenga LH, Boerrigter L, Top B, Rodenhuis S,Langeveld A, Mulder MP, Oosterhuis JW. 1995. N- and KRASmutations in primary testicular germ cell tumors: Incidence andpossible biological implications. Genes Chromosomes Cancer12:110–116.
Oliver RT. 1987. HLA phenotype and clinicopathological behaviourof germ cell tumors: Possible evidence for clonal evolution fromseminomas to nonseminomas. Int J Androl 10:85–93.
Ondrus D, Kuba D, Chrenova S, Matoska J. 1997. Familial testicularcancer and developmental anomalies. Neoplasma 44:59–61.
Oosterhuis JW, Castedo SM, de Jong B, Cornelisse CJ, Dam A, Sleij-fer DT, Schraffordt Koops H. 1989. Ploidy of primary germ celltumors of the testis. Pathogenetic and clinical relevance. LabInvest 60:14–21.
Oosterhuis JW, Looijenga LH. 2005. Testicular germ-cell tumors ina broader perspective. Nat Rev Cancer 5:210–222.
Ottesen AM, Skakkebaek NE, Lundsteen C, Leffers H, Larsen J,Rajpert-De Meyts E. 2003. High-resolution comparative genomichybridization detects extra chromosome arm 12p material in mostcases of carcinoma in situ adjacent to overt germ cell tumors, butnot before the invasive tumor development. Genes ChromosomesCancer 38:117–125.
Parkin DM, Iscovich J. 1997. Risk of cancer in migrants and theirdescendants in Israel. II. Carcinomas and germ-cell tumors. Int JCancer 70:654–660.
Pero SC, Oligino L, Daly RJ, Soden AL, Liu C, Roller PP, Li P,Krag DN. 2002. Identification of novel non-phosphorylatedligands, which bind selectively to the SH2 domain of Grb7. J BiolChem 277:11918–11926.
Pero SC, Shukla GS, Armstrong AL, Peterson D, Fuller SP, GodinK, Kingsley-Richards SL, Weaver DL, Bond J, Krag DN. 2004.Identification of a small peptide that inhibits the phosphorylationof ErbB2 and proliferation of ErbB2 overexpressing breast cancercells. Int J Cancer 111:951–960.
Pettersson A, Kaijser M, Richiardi L, Askling J, Ekbom A, Akre O.2004. Women smoking and testicular cancer: One epidemic caus-ing another? Int J Cancer 109:941–944.
Rapley EA, Crockford GP, Easton DF, Stratton MR, Bishop DT.2003. Localisation of susceptibility genes for familial testiculargerm cell tumor. Apmis 111:128–133; discussion 33–35.
Rapley EA, Crockford GP, Teare D, Biggs P, Seal S, Barfoot R,Edwards S, Hamoudi R, Heimdal K, Fossa SD, Tucker K, DonaldJ, Collins F, Friedlander M, Hogg D, Goss P, Heidenreich A,Ormiston W, Daly PA, Forman D, Oliver TD, Leahy M, HuddartR, Cooper CS, Bodmer JG, Easton DF, Stratton MR, Bishop DT.2000. Localization to Xq27 of a susceptibility gene for testiculargerm-cell tumors. Nat Genet 24:197–200.
Rapley EA, Hockley S, Warren W, Johnson L, Huddart R, CrockfordG, Forman D, Leahy MG, Oliver DT, Tucker K, Einhorn L,Weber BL, McMaster M, Greene MH, Bishop DT, Easton D,Stratton MR. 2004. Somatic mutations of KIT in familial testicu-lar germ cell tumours. Br J Cancer 90:2397–2401.
Richiardi L, Akre O, Lambe M, Granath F, Montgomery SM,Ekbom A. 2004a. Birth order, sibship size, and risk for germ-celltesticular cancer. Epidemiology 15:323–329.
Richiardi L, Bellocco R, Adami HO, Torrang A, Barlow L, Hakuli-nen T, Rahu M, Stengrevics A, Storm H, Tretli S, Kurtinaitis J,Tyczynski JE, Akre O. 2004b. Testicular cancer incidence in eightnorthern European countries: Secular and recent trends. CancerEpidemiol Biomark Prev 13:2157–2166.
Roelofs H, Mostert MC, Pompe K, Zafarana G, van Oorschot M,van Gurp RJ, Gillis AJ, Stoop H, Beverloo B, Oosterhuis JW,Bokemeyer C, Looijenga LH. 2000. Restricted 12p amplificationand RAS mutation in human germ cell tumors of the adult testis.Am J Pathol 157:1155–1166.
Ronnstrand L. 2004. Signal transduction via the stem cell factorreceptor/c-Kit. Cell Mol Life Sci 61:2535–2548.
Genes, Chromosomes & Cancer DOI 10.1002/gcc
556 MCINTYRE ETAL.
![Page 11: Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults](https://reader035.vdocuments.us/reader035/viewer/2022080306/5750048b1a28ab11489f5596/html5/thumbnails/11.jpg)
Rosenberg C, Van Gurp RJ, Geelen E, Oosterhuis JW, LooijengaLH. 2000. Overrepresentation of the short arm of chromosome 12is related to invasive growth of human testicular seminomas andnonseminomas. Oncogene 19:5858–5862.
Ross JS, Fletcher JA, Bloom KJ, Linette GP, Stec J, Symmans WF,Pusztai L, Hortobagyi GN. 2004. Targeted therapy in breast can-cer: The HER-2/neu gene and protein. Mol Cell Proteomics3:379–398.
Satge D, Sasco AJ, Cure H, Leduc B, Sommelet D, Vekemans MJ.1997. An excess of testicular germ cell tumors in Down’s syn-drome: Three case reports and a review of the literature. Cancer80:929–935.
Sharpe RM. 2003. The ‘oestrogen hypothesis’- where do we standnow? Int J Androl 26:2–15.
Skakkebaek NE. 1972. Possible carcinoma-in-situ of the testis.Lancet 2:516–517.
Skakkebaek NE. 2002. Endocrine disrupters and testicular dysgene-sis syndrome. Horm Res 57Suppl 2:43.
Skakkebaek NE. 2003. Testicular dysgenesis syndrome. Horm Res60Suppl 3:49.
Skakkebaek NE, Holm M, Hoei-Hansen C, Jorgensen N, Rajpert-De Meyts E. 2003. Association between testicular dysgenesis syn-drome (TDS) and testicular neoplasia: Evidence from 20 adultpatients with signs of maldevelopment of the testis. Apmis 111:1–9; discussion 9–11.
Skakkebaek NE, Rajpert-De Meyts E, Main KM. 2001. Testiculardysgenesis syndrome: An increasingly common developmentaldisorder with environmental aspects. Hum Reprod 16:972–978.
Skotheim RI, Lind GE, Monni O, Nesland JM, Abeler VM, FossaSD, Duale N, Brunborg G, Kallioniemi O, Andrews PW, LotheRA. 2005. Differentiation of human embryonal carcinomas invitro and in vivo reveals expression profiles relevant to normaldevelopment. Cancer Res 65:5588–5598.
Sommerer F, Hengge UR, Markwarth A, Vomschloss S, StolzenburgJU, Wittekind C, Tannapfel A. 2005. Mutations of BRAF andRAS are rare events in germ cell tumors. Int J Cancer 113:329–335.
Sperger JM, Chen X, Draper JS, Antosiewicz JE, Chon CH, JonesSB, Brooks JD, Andrews PW, Brown PO, Thomson JA. 2003.Gene expression patterns in human embryonic stem cells andhuman pluripotent germ cell tumors. Proc Natl Acad Sci USA100:13350–13355.
Stallock J, Molyneaux K, Schaible K, Knudson CM, Wylie C. 2003.The pro-apoptotic gene Bax is required for the death of ectopicprimordial germ cells during their migration in the mouseembryo. Development 130:6589–6597.
Strohmeyer T, Peter S, Hartmann M, Munemitsu S, Ackermann R,Ullrich A, Slamon DJ. 1991. Expression of the hst-1 and c-kitprotooncogenes in human testicular germ cell tumors. Cancer Res51:1811–1816.
Strohsnitter WC, Noller KL, Hoover RN, Robboy SJ, Palmer JR,Titus-Ernstoff L, Kaufman RH, Adam E, Herbst AL, Hatch EE.2001. Cancer risk in men exposed in utero to diethylstilbestrol.J Natl Cancer Inst 93:545–551.
Summersgill B, Osin P, Lu YJ, Huddart R, Shipley J. 2001. Chromo-somal imbalances associated with carcinoma in situ and associatedtesticular germ cell tumours of adolescents and adults. Br J Can-cer 85:213–220.
Swerdlow AJ, Higgins CD, Pike MC. 1997. Risk of testicular cancerin cohort of boys with cryptorchidism. Bmj 314:1507–1511.
Teng DH, Hu R, Lin H, Davis T, Iliev D, Frye C, Swedlund B,Hansen KL, Vinson VL, Gumpper KL, Ellis L, El-Naggar A,Frazier M, Jasser S, Langford LA, Lee J, Mills GB, PershouseMA, Pollack RE, Tornos C, Troncoso P, Yung WK, Fujii G, BersonA, Steck PA. 1997. MMAC1/PTEN mutations in primary tumorspecimens and tumor cell lines. Cancer Res 57:5221–5225.
Ulbright TM. 1993. Germ cell neoplasms of the testis. Am J SurgPathol 17:1075–1091.
van Gurp RJ, Oosterhuis JW, Kalscheuer V, Mariman EC, LooijengaLH. 1994. Biallelic expression of the H19 and IGF2 genes inhuman testicular germ cell tumors. J Natl Cancer Inst 86:1070–1075.
Viglietto G, Romano A, Maglione D, Rambaldi M, Paoletti I, LagoCT, Califano D, Monaco C, Mineo A, Santelli G, Manzo G, BottiG, Chiappetta G, Persico MG. 1996. Neovascularization in humangerm cell tumors correlates with a marked increase in the ex-pression of the vascular endothelial growth factor but not theplacenta-derived growth factor. Oncogene 13:577–587.
von Eyben FE, Jacobsen GK, Rorth M, Von Der Maase H. 2004.Microinvasive germ cell tumor (MGCT) adjacent to testiculargerm cell tumors. Histopathology 44:547–554.
Watanabe S, Umehara H, Murayama K, Okabe M, Kimura T,Nakano T. 2006. Activation of Akt signaling is sufficient to main-tain pluripotency in mouse and primate embryonic stem cells.Oncogene 25:2697–2707.
Waterhouse JA. 1985. Epidemiology of testicular tumors. J R SocMed 78 Suppl 6:3–7.
Weir HK, Marrett LD, Kreiger N, Darlington GA, Sugar L. 2000.Pre-natal and peri-natal exposures and risk of testicular germ-cellcancer. Int J Cancer 87:438–443.
Wennerberg K, Rossman KL, Der CJ. 2005. The Ras superfamily ata glance. J Cell Sci 118:843–846.
Willmore-Payne C, Holden JA, Tripp S, Layfield LJ. 2005. Humanmalignant melanoma: Detection of BRAF- and c-kit-activatingmutations by high-resolution amplicon melting analysis. HumPathol 36:486–493.
Ye DW, Zheng J, Qian SX, Ma Y, Zheng X, Li D, Gu S. 1993. p53gene mutations in Chinese human testicular seminoma. J Urol150:884–886.
Yu Q, Ciemerych MA, Sicinski P. 2005. Ras and Myc can drive onco-genic cell proliferation through individual D-cyclins. Oncogene24:7114–7119.
Zhang Y, Graubard BI, Klebanoff MA, Ronckers C, Stanczyk FZ,Longnecker MP, McGlynn KA. 2005. Maternal hormone levelsamong populations at high and low risk of testicular germ cellcancer. Br J Cancer 92:1787–1793.
Genes, Chromosomes & Cancer DOI 10.1002/gcc
557TESTICULAR GERM CELL TUMOR DEVELOPMENT