mechanism of oncogenes Flashcards
describe cancer
disease of ageing abnormal cell proliferation tumour formation invasion of normal tissue metastasis to form new tumours at distant sites over 200 diff types
define carcinoma
occurs in epithelial cells
define sarcoma
derived from mesoderm cells (bone + muscle)
define adenocarcinomas
in glandular tissue
describe the hallmarks of cancer
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
describe somatic mutations
almost all mutations in tumour cells, non inheritable
what is proliferation
cell loss and apoptosis to balance
describe oncogenes
normal genes activated to be oncogenic = proto-oncogenes
oncogene = porto-oncogenes mutated leading to signals causing uncontrolled growth
what is a tumour suppressor gene
inhibit growth and tumour formation
what are chemical carcinogens
can alter any step of initiation/promotion/progression of cancer
what’re the 4 classes of carcinogens
- chemical = hydrocarbons/aromatic amines/azodyes
- radiation
- heritable
- viral
describe chemical carcinogens
4 main = polycyclic aromatic hydrocarbons, aromatic amines, nitrosamines, alkylating agents
what is the Ames test
- rat liver extracted and salmonella strain
- place to agar > incubate and possible mutagen
- check colonies overal
describe syndromes predisposing to cancer
DNA repair defects
- ataxia telangiectasia
- blooms syndrome
- fanconi’s anaemia
- li-fraumeni syndrome
chromosomal abnormalities
- down’s
- klinfelters
properties required of tumorigenic viruses
- stable association with cells = chromosomal integration episome
- must not kill cells
- must evade immune surveillance of infected cells
name viruses associated with human cancer
- DNA virus = epstein, papuloma, hepatitis B and C
2. RNA retroviruses = HTVL-1
define non-genotoxic
act as tumour promoters/endocrine modifiers/receptor mediators/immunosuppressors/inducers of tissue specific toxicity and inflammatory response
what is the somatic mutation theory
cancer derived from single somatic cell with many DNA mutations which damage genes and neoplastic lesions occur
what is the tissue organisation field theory
carcinogenesis = primary problem of tissue organization and carcinogenic agents destroy normal tissue architecture
DNA mutations are random
cancer immunoediting
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
