mechanism of oncogenes

Question 1

describe cancer

Answer 1

disease of ageing 
abnormal cell proliferation
tumour formation 
invasion of normal tissue
metastasis to form new tumours at distant sites 
over 200 diff types

Question 2

define carcinoma

Answer 2

occurs in epithelial cells

Question 3

define sarcoma

Answer 3

derived from mesoderm cells (bone + muscle)

Question 4

define adenocarcinomas

Answer 4

in glandular tissue

Question 5

describe the hallmarks of cancer

Answer 5

evading growth suppressors 
avoiding immune destruction 
enabling replicative immortality 
tumour promoting inflammation 
activating invasion and metastasis 
inducing angiogenesis 
genome instability and mutation 
resisting cell death 
deregulating cellular energetics

Question 6

describe somatic mutations

Answer 6

almost all mutations in tumour cells, non inheritable

Question 7

what is proliferation

Answer 7

cell loss and apoptosis to balance

Question 8

describe oncogenes

Answer 8

normal genes activated to be oncogenic = proto-oncogenes

oncogene = porto-oncogenes mutated leading to signals causing uncontrolled growth

Question 9

what is a tumour suppressor gene

Answer 9

inhibit growth and tumour formation

Question 10

what are chemical carcinogens

Answer 10

can alter any step of initiation/promotion/progression of cancer

Question 11

what’re the 4 classes of carcinogens

Answer 11

1. chemical = hydrocarbons/aromatic amines/azodyes
2. radiation
3. heritable
4. viral

Question 12

describe chemical carcinogens

Answer 12

4 main = polycyclic aromatic hydrocarbons, aromatic amines, nitrosamines, alkylating agents

Question 13

what is the Ames test

Answer 13

1. rat liver extracted and salmonella strain
2. place to agar > incubate and possible mutagen
3. check colonies overal

Question 14

describe syndromes predisposing to cancer

Answer 14

DNA repair defects

• ataxia telangiectasia
• blooms syndrome
• fanconi’s anaemia
• li-fraumeni syndrome

chromosomal abnormalities

• down’s
• klinfelters

Question 15

properties required of tumorigenic viruses

Answer 15

1. stable association with cells = chromosomal integration episome
2. must not kill cells
3. must evade immune surveillance of infected cells

Question 16

name viruses associated with human cancer

Answer 16

1. DNA virus = epstein, papuloma, hepatitis B and C

2. RNA retroviruses = HTVL-1

Question 17

define non-genotoxic

Answer 17

act as tumour promoters/endocrine modifiers/receptor mediators/immunosuppressors/inducers of tissue specific toxicity and inflammatory response

Question 18

what is the somatic mutation theory

Answer 18

cancer derived from single somatic cell with many DNA mutations which damage genes and neoplastic lesions occur

Question 19

what is the tissue organisation field theory

Answer 19

carcinogenesis = primary problem of tissue organization and carcinogenic agents destroy normal tissue architecture
DNA mutations are random

Question 20

cancer immunoediting

Answer 20

elimination = immune system can eradicate developing tumours 
equilibrium = incomplete removal present = tumour cells remain dormant and enter equilibrium 
escape = expanding tumour populations become clinically detectable