signal trans duct ion 1- 2011

8/6/2019 Signal Trans Duct Ion 1- 2011

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SENYALITZACI CEL.LULAR I CNCER

(TEMA 5)


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Introduction; Signal transduction pathways and Cancer.

Growth factors

Tyrosine Kinase receptors

MAP kinase cascades. RAS, ERK, JNK and p38 MAP Kinase

PI 3-kinase: PKB; mTOR, GSK3-, catenin

Other cascades: TGF- , STAT, FAK

Transcription Factors: fos, jun, myc


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Divide or not divide: a critical decision

Mitogens

Cell cycle controlers

Mitogens controlthe celular decisionto proliferate

ProliferationDifferentiationSurvival

ApoptosisSenescence

Celular decisions:


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M

G1

S

G2

R

G0

CDK4

cic D

CDK2

cic E

CDK2

cic A

CDC2

cic B

DE

AB

CDKs

niveles

de

prote

na

G1 S G2 M

SENYALS EXTERNES


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Figure 8.22 The Biology of Cancer( Garland Science 2007)

E2F


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GROWTH FACTOR

CDK

Cyc

synthesis

degradation

CKIs

T161

T14

Y15

KinasePhosphatase

Kinases

CaK Kap1

Wee1

Myt1

p21, p27, p57

binding to: cdk4-6/cycD

inhibition of: cdk2/cycE-A

p16, p15, p18, p19binding to: cdk4-6

inhibition of

Phosphatasecdc25

- Cyclin-CDK assembly - intracellular localization


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Proliferation = cell division + growth

Growth Factor

Growth Factor

growth

cell division


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Growth factor induce: cell cycle, growth, morphologic changes...


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Growth factors activates early genes


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Signal transduction involves proteinphosphorylation and protein interaction

A. 518 kinases; ~180 phosphatases.

B. ~One-third of all proteins areregulated by reversible phosphorylation.

C. Substrate targets:Kinase: ~15-20Phosphatase: ~50


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Fig. 2Hanahan and Weinberg

Cell 100:57


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-What are the signal transduction

pathways involved?-What are the targets of thesepathways?-How do these targets evoke changes

leading to cancer?

Frequently asked questions when studyingcancer cell signal transduction


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Growth Factor:are proteins that bind to receptor on the

cell surface with primary result of activating cellular

proliferationand or differentiationEpidermal Growth Factor (EGF)Platelet-Derived Growth Factor (PDGF)

Fibroblast Growth Factors (FGFs)Transforming Growth Factors-b TGFs-)

Transforming Growth Factor-a (TGF-)

Erythropoietin (Epo)

Insulin-Like Growth Factor-I (IGF-I)Insulin-Like Growth Factor-II (IGF-II)

Interleukin-1 (IL-1)

Interleukin-2 (IL-2)

Interleukin-6 (IL-6)Interleukin-8 (IL-8)

Tumor Necrosis Factor-a (TNF-)

Tumor Necrosis Factor-b (TNF-)

Interferon-g (INF-)

Colony Stimulating Factors (CSFs)

Citokines:

secreted primarily from leukocytes


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related to IGF-I and proinsulinpromotes proliferation of many cell

types primarily of fetal origin

variety of cellsIGF-II

related to IGF-II and proinsulin, also called

Somatomedin C

promotes proliferation of many cell

types

primarily liverIGF-I

at least 100 different family membersanti-inflammatory (suppressescytokine production and class II

MHC expression), promotes wound

healing, inhibits macrophage and

lymphocyte proliferation

activated TH1cells (T-helper)

and natural killer

(NK) cells

TGF-

promotes proliferation anddifferentiation of erythrocytes

kidneyErythropoietin

several related proteins first identified as

proto-oncogenes; trkA (trackA), trkB, trkC

promotes neurite outgrowth and

neural cell survivalNGF

at least 19 family members, 4 distinctreceptors

promotes proliferation of many cells;inhibits some stem cells; induces

mesoderm to form in early embryos

wide range ofcells; protein is

associated with

the ECM

FGF

related to EGFmay be important for normal wound

healing

common in

transformed

cells

TGF-

promotes proliferation ofmesenchymal, glial and epithelial

cells

submaxillary

gland, Brunners

gland

EGF

two different protein chains form 3 distinct

dimer forms; AA, AB and BB

promotes proliferation of connective

tissue, glial and smooth muscle cells

platelets,

endothelial cells,placenta

PDGF

CommentsPrimary ActivityPrincipal

SourceFactor

Growth Factors


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EGF (epidermal growth factor)

* 1962 Dr. Stanley Cohen. Allat de glndules submaxil.lar de ratol. 1986Premi Nobel

*pptid de 53-58 aa ( 6000 Da). Difereix segons espcie

* Processament: sntesi com a pre-pro-EGF (1200.000)

pro-EGF (9.000)EGF (6.045)

*Estructura: protena transmembrana. Sequncia hidrofbica, 3 ponts de

disulfur

PRO EGFN-

TMSP

preproEGF

22 978 1023 1207


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Familia de lepidermal growth factor

HB-EGF: Hepatin-binding EGF

AR: Amphiregulin

BTC-betacellulin

EPR-epigeregulin

TGFN-TMSP

preproTGF


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Maturation of EGF: role of metalloproteases

In many cellular systems, EGF-like factors undergo constitutive shedding in

the absence of any stimulation In addition to constitutive shedding,

shedding of many transmembraneproteins can be up-regulated by a range of

chemical stimuli such as phorbol esters, calcium ionophores, calmodulin

inhibitors........

A number of different subtypes of metalloprotease families including

ADAMs matrix metalloprotease and membrane type matrix metalloproteases (MT-MMPs)

have been implicated in the ectodomain shedding of transmembrane proteins including

EGFlike factors.


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Figure 5.12b The Biology of Cancer( Garland Science 2007)

Deregulaton of receptor:autocrine signaling


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Table 5.3 The Biology of Cancer( Garland Science 2007)


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Growth Factors as Oncogenes

v-sis carried by simian sarcoma virus is derived from PDGF,

and c-sis is amplified in glioma.

int-2 was identified as a MMTV integration is related to FGFand is amplified in human breast carcinoma.

hst was isolated from stomach cancer and is amplified

(along with int-2) in head and neck tumors.


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Structure of tyrosine kinase receptors


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Activation of tyrosine kinase receptor:

dimeritation & autophosphorylation


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Phosphorylation: a quick process


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Schlessinger, (2000)Cell 103, 211-225

Dimeric assembly of 2 FGF2:FGFR1 complexes. FGF2 is colored orange, Ig-like domain 2 of FGFR1 is colored green, and Ig-like domain 3 of FGFR1 is

colored cyan. [Plotnikov et al., Cell 98, 641 (1999)]

Dimeritation


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Three-dimensional structures of the

insulin receptor tyrosine kinase (IRK)IRK conformational change upon activation

loop phosphorylation. The N-terminal

lobe of IRK is colored white and the C-

terminal lobe is colored dark grey. The

activation loop (green) containsautophosphorylation sites Y1158, Y1162

and Y1163, and the catalytic loop

(orange) contains the putative catalytic

base, D1132. Also shown are the

unbound/bound ATP analog and

tyrosine-containing substrate peptide

(pink). [Hubbard, EMBO J. 16, 5572(1997)]


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SH2: Src-homology 2 domain

1991: was originally defined in the sarcana retroviral

oncoprotein v-Fpssequence of around 100 aa (antiparallel -sheet between

two -helices)

bind to phosphotyrosine and between 3-6 residues C-

terminal


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Figure 6.8a The Biology of Cancer( Garland Science 2007)

SH2 is specific for P-tyrosine and flanking amino acid region


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Protein-protein interaction through

specific domains


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Table 5.2 The Biology of Cancer( Garland Science 2007)

transformation due to:

over-expression, point mutation,

truncation of ectodomain, gene fusion....

Alteration of tyrosine kinase receptor in human tumors


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presentaci: Dr. Maggi Coplin

OVER-EXPRESSION


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V-Erb, a trucated form of EGFR

truncation of ectodomain


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Gene fusion receptors


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Growth Factor Receptors in Leukemia

chronic myelomonocytic leukemia with t(5;12)

DZ ETS-DBDTEL

TMLigand Kinase

PDGFR

t(5;12) DZTEL- PDGFR Fusion

Kinase

PDGFR;

Must dimerize to transduce

a signal

TEL is a transcriptionfactor with a strongdimerization domain.

Dimerized in absense of ligand - always on


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Point mutation:

constitutive active receptor


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KIT mutations

GIST (gastrointestinal estromal tumours) Most KIT mutations effect

exon 11, others 9,13,17

The type of exon 11 deletion

may affect prognosis:deletions of codons 562 to579 (563-569 always

malignant)

Exon 11 mutations are more

likely to respond to iminitab


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Imatinib (Gleevec) a Tyrosine

Kinase Inhibitor Imatinib mesylate is a protein-tyrosine

kinase inhibitor that inhibits the Bcr-Abl tyrosine kinase, the constitutiveabnormal tyrosine kinase created bythe Philadelphia chromosome

abnormality in chronic myeloid leukemia(CML).

Imatinib is also an inhibitor of thereceptor tyrosine kinases for platelet-derived growth factor (PDGF) and stemcell factor (SCF), c-kit, and inhibitsPDGF- and SCF-mediated cellularevents. In vitro, imatinib inhibitsproliferation and induces apoptosis ingastrointestinal stromal tumor (GIST)cells, which express an activating c-kitmutation

signal trans duct ion 1- 2011

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