Lecture 13: Cancer 1 Flashcards
% of individual cancers in each places varies suggesting environment
effects chance
migrant studies link
genetic and environmental data
Causes of cancer:
- environmental causes/carcinogens
- viral infections
- inherited factos
- genetic instability
environmental causes of cancer e.g.
- occupational exposure :various
- tobacco related: lung,kidney,bladder
- tobacco &alcohol: mouth&thrat
- diet (low in veg,high salt,high nitrate): stomach oesophagus
- diet (high fat, low finer,fried and broiled): bowel, pancreas prostate breast
Causes of cancer: viral
first tumour virus discovered
- discovered & named after Peyton Rous in 1910
- Rous Sarcoma Virus (RSV)
- boble prize 1966
e. g.s: EBV, Kaposi’s sarcoma, HHV8, HPV16 & 18
causes of cancer: inherited factors e.g.
- Retinoblastoma
- Li Fraumeni
- Wilm’s tumour
- Gorlin’s syndrome
- Breast cancer
- Familial adenomatous polyposis coli (FAP)
cause of cancer: Genetic instability
Chronic Myeloid Leukaemia (CML)
CML:
small chromosome named the Philadelphia chromosome (Ph)
First evidence for a consistent chromosome change (Genomic Instability) in cancer
Ph translocation:
- Fusion of two genes:
- -ABL (9q34)
- -BCR (22q11)
ABL is a
ABL (a proto-oncogene)
encodes a nuclear tyrosine kinase protein
= positive regulator of cell growth
BCR/ABL =
= abnormal fusion protein
⇒ ⇑tyrosine kinase activity
⇒leads to increased proliferation and malignant (evil) growth
Ph translocation and fusion of two genes =
proto-oncogene –> oncogene
other examples of oncogenes:
Ret & Myc
most cancer-causing viruses contain an
oncogene!
Probably by evolutionary capture and mutation of proto-oncogene
Many cancers arise from defects in the machinery that regulates
cell growth and/or cell death
