Liyan Xu

OncogeneCancer suppressive gene

The basic concept

1 oncogene:

These genes code for proteins that are capable of stimulating cell growth and division.

In normal tissues and organisms, such growth-stimulating proteins are regulated, so that growth is appropriately limited.

However, changes/mutation in these genes may result in loss of growth regulation, leading to uncontrolled cell proliferation and tumor development.

These changed genes are known as oncogenes, because they induce the oncogenic state — cancer.

Oncogenes are dominant, because a change/mutation of only one of the cell’s two copies of that gene can lead to tumor formation.

The basic concept

2 proto-oncogenes:

The normal precurcers of these above genes are termed proto-oncogenes and are essential for normal cell growth and differentiation.

proto-oncogenes is also called as cellular oncogenes.

3 virus oncogene:

these genes are in viruses, may leading to uncontrolled cell proliferation and tumor development.

Virus oncogenes are homolog with that corresponding cellular oncogenes.

The basic concept

4 cancer suppressive genes:

These genes code for proteins whose normal function is to turn off cell growth.

A change/mutation in one of these growth-limiting genes may result in a protein product that has lost its growth limiting ability.

The normal forms of such gense have been shown to suppress tumor growth and are known as tumor suppressor genes or anti-oncogenes as well.

Because both cellular copies of a tumor suppressor gene must be mutated to foil its growth-limiting action, these genes are recessive in nature.

Fig. 20-1 Structure of RSV genome

9392 bp

LTR LTRgag pol env src

tyrosine kinase

526 residue

60 kD

wide type viral genes oncogene

to initiate

and regulate

transcription

The pp60V-SRC is anchored to the plasma membrane via an N-terminal myristyl group

Fig. 20-2 Integration of RNA virus genome and host cell genome

RNA virus

+

+

+

provirus DNA

virus RNA

host cell

c-onc.

v-onc.

Mechanism on oncogene activated

to obtain a strong promoter or enhancer.

gene translocation.

protooncogene amplification in the genome.

point mutation

to obtain a strong promoter or enhancer.

avian leukemiavirus genome

host cellgenome

ssRNA

dsDNA

c-mycLTR

to increase c-myc gene expression, 30-100 times, compare with no infection.

Mechanism on oncogene activated

to obtain stronge a promoter or a enhancer.

gene translocation.

protooncogene amplification in the genome.

point mutation

Burkit lymphoma

14 chromosome

IgH gene regulation region8 chromosome

c-myc

to increase c-myc gene expression obviously

t （ 8:14 ）

Mechanism on oncogene activated

to obtain stronge a promoter or a enhancer.

gene translocation.

protooncogene amplification in the genome.

point mutation

ras or c-myc

expression of ras or c-myc is increased obviously

amplification

1

2

3

n

Mechanism on oncogene activated

to obtain stronge a promoter or a enhancer.

gene translocation.

protooncogene amplification in the genome.

point mutation

GGC

GTC

H-ras

Gly

Val

DNA Protein

carcinoma

normal

nucleus

cytoplasm

membrane

extracellularSIS

PDGF receptor

RAS/Gpro.

erbB-2

EGF

kinase

targets targets

SRC

DNA

mRNA RNA pol.

targets

kinase

cAMP

DG PKC

ER

Ca2+

AA

AC

PGPKA

targets

kinase

effects

effects

PIP2

+

Fig. 20-3 Oncogene and signal transduction for growth 418

PLC

PLA2 IP3

nucleus

cytoplasm

membrane

extracellularSIS

PDGF receptor

RAS/Gpro.

erbB-2

EGF

kinase

targets targets

SRC

DNA

mRNA RNA pol.

targets

kinase

cAMP

DG PKC

ER

Ca2+

AA

AC

PGPKA

targets

kinase

effects

effects

PIP2

+

Fig. 20-3 Oncogene and transduction of information for growth 418

PLC

PLA2 IP3

Phospho-rylation site

nucleus

cytoplasm

membrane

extracellularSIS

PDGF receptor

RAS/Gpro.

erbB-2

EGF

kinase

targets targets

SRC

DNA

mRNA RNA pol.

targets

kinase

cAMP

DG PKC

ER

Ca2+

AA

AC

PGPKA

targets

kinase

effects

effects

PIP2

+

Fig. 20-3 Oncogene and transduction of information for growth 418

PLC

PLA2 IP3

Ca2+

nucleus

cytoplasm

membrane

extracellularSIS

PDGF receptor

RAS/Gpro.

erbB-2

EGF

kinase

targets targets

SRC

DNA

mRNA RNA pol.

targets

kinase

cAMP

DG PKC

ER

Ca2+

AA

AC

PGPKA

targets

kinase

effects

effects

PIP2

+

Fig. 20-3 Oncogene and transduction of information for growth 418

PLC

PLA2 IP3

tumor suppressor genes

two examples

Rb: 13q14.1-14.2, 27 exon, complete length 180 kb, mRNA 4.7

kb, encoding protein 105 kD, 928 residues, locate in nucleus, i

nactive form: phosphorylation Rb, active form: non-phosphor

ylation Rb, be able to bind activated transcription factor E-2F,

be able to inhibite RNA polymerase I and RNA polymerase II

I .

p53: 17p13, 11 exon, complete length 16-20 kb, mRNA 2.8 kb,

encoding protein 53 kD, 393 residues, locate in nucleus, is pho

sphorylated, tetramer.

cell DNA damage p53

damaged DNA repair

cell apoptosis cell survive

repair is successful by p53repair is unsuccessful by p53

Oncogene and tumor suppresor gene Our experiment result about the oncogenes and tumor supp

ressor genes for esophageal cancer

normalembryo

esophagealepithelial

cell

human papilloma virus E6 and E7 genes

plasmidimmortal esophagealcelltransfection

12-o-tetradecanoylphorbol-13-acetate,TPA carcinogen

esophagealcancer cell

canceration

difference cDNA clone

mRNA difference

updown

cDNA arrayup clone: 33

down clone: 28

suppression subtractive

hybridizationup clone :62

down clone:56

Summary

The basic concept: oncogene, proto-oncogene, virus oncogene,

tumor suppressor gene

Mechanism on oncogene activated

Function of oncogene and tumor suppressor gene

选择题练习癌基因与抑癌基因

1. 细胞原癌基因

A 正常人细胞也检测到的癌基因

B 只在肿瘤细胞中出现

C 加入化学致癌物到正常细胞后才出现

D 是细胞经过转化才出现

E 感染致癌病毒才出现

2. 关于细胞癌基因 , 正确的叙述是

A 存在于 RNA 病毒中

B 存在于 DNA 病毒中

C 存在于正常细胞基因组中

D 正常细胞出现可导致肿瘤

E 只存在于肿瘤细胞细胞

3. 致癌病毒

A 使人体直接致癌

B 使正常细胞转化为癌细胞

C 均为 DNA 病毒

D 均为 RNA 病毒

E 含转化酶

4. 不属于癌基因产物的是

A 化学致癌物

B 生长因子类似物

C 结合 GTP 的蛋白质

D 结合 DNA 的蛋白质

E 酪氨酸蛋白激酶

5. 有关抑癌基因 , 错误的叙述是

A 能抑制细胞的分化

B 能抑制细胞过度生长

C 突变后可导致肿瘤形成

D 可诱导细胞凋亡

E 最早发现的抑癌基因是 Rb

6. 有关 P53 蛋白 , 错误的描述是

A 其基因位于 17p13, 突变后可致癌

B 能引发修复失败的细胞程序自杀

C 有“基因卫士”的称号

D 有转录因子作用

E 能激活解链酶

7. 有关 Rb 基因 , 错误的描述是

A 位于 13q14

B 是一种抑癌基因

C 其作用与 E-2F 有关

D 其编码蛋白为 P21

E 突变后可导致肿瘤发生

8. 关于凋亡 , 正确的叙述是

A 是一种病理过程

B 是细胞坏死

C 由意外事件引起的细胞损伤造成

D 由基因控制的细胞自我消亡的过程

E 与癌基因的表达调控无关

9. 生殖细胞抑癌基因的突变可引起

A 生殖功能障碍

B 各种先天性的肿瘤

C 家族性的肿瘤易感性

D 后代的发育正常

E 家族性癌症发病率下降

10. 使癌基因活化的因素有

A 正常基因表达增强

B 正常基因表达减少

C 抑癌基因表达增强

D 细胞增殖、分化加强

E 点突变

11. The oncogene which can encode epidermal growth factor receptor is

A src

B ras

C myc

D sis

E erb-B

12. The oncogene which can encode GTP binding protein is

A src

B ras

C myc

D sis

E erb-B

13. The oncogene which can encode protein

having TPK activity is

A src

B ras

C myc

D sis

E erb-B

14. Which isn’t a anti-oncogene?

A P16

B P53

C Rb

D WT1

E H-ras

15. 正常基因的异常表达可致

A 细胞形态改变

B 细胞癌变

C 异常表型

D 细胞结构与生物活性改变

E 细胞凋亡

16. 细胞癌基因可在下列情况下激活

A 基因发生突变

B 有化学致癌剂存在

C 有病毒感染

D 生长因子与 DNA 互相结合

E 受体激活

17. 野生型 P53 基因

A. 是抑制基因

B. 一定情况下 , 能启动细胞自杀

C. 编码蛋白有转录因子作用

D. 能抑制解链酶活性

E. 与复制因子 A 相互作用 , 参与 DNA 的复制与修复

18. Rb 基因的特点

A 位于 13q14

B 含 27 个外显子

C 编码产物 105KD

D 转录产物 4.7kb

E 全长 20 kb

19. Which is oncogene expression product?

A GTP binding proteins

B DNA binding proteins

C tyrosine protein kinase

D growth factors

E cytoskeletal proteins

20. The activation ways of proto-oncogene are

A point mutation

B gene translocation

C gene amplification

D protein phosphorylation

E obtaining promoter