Revision of Cancer Biology Flashcards
What are the most common causes of cancer deaths?
Breast
Prostate
Lung
Bowel
What are the hallmarks of cancer cells?
- growth signal not required for cell survival, growth and differentiation
- unresponsiveness to growth-inhibitory signals
- evasion of apoptosis
- defects in DNA repair
- cells become immortal (limitless reproduction potential)
- ability to invade and metastasise
- angiogenesis sustained and increased
What types of mutations involve proto-oncogenes?
- translocation/transposition
- gene amplification
- point mutations
What translocations/transpositions involve proto-oncogenes?
- new promotor added to gene switching the gene on = abnormal growth
- Bcl2 is anti-apoptotic
- overexpression of t14:18, q32:21
- leads to follicular lymphoma
What is an example of gene amplification?
- HER2/ErB2
- overexpression of GF
- invasive breast carcinoma
What are 2 examples of point mutations?
In a gene/coding region (c-H-ras) or non-coding region (c-Fos)
What is point mutation occurring within a coding region?
- occurs within the gene:
- c-H-ras
- glycine to valine
- bladder cancer
What is a point mutation occurring in a non-coding region?
- occurs in non-coding region (promoter/enhancer region)
- c-Fos (TF)
- melanoma
How are oncogenes dominantly active?
- GF
- receptors
- signal transduction proteins
- TF
- pro/anti-apoptotic proteins
What are some examples of GF oncogenes?
- EGF
- HER2
What are some examples of GF receptor oncogenes?
- EGF
- VEGF
What are some examples of signal-transduction proteins?
- KRAS
- B-Raf
What are some examples of TF oncogenes?
c-mvc
What are some examples of anti-apoptotic protein oncogenes?
Bcl-2
How do tumour suppressor genes work?
- loss of function
- point mutations
- divided into gatekeeper genes, caretaker genes and pro-apoptotic genes
How do tumour suppressor genes allow protein mutations?
- within control element (Bax which is an anti-apoptotic protein)
- within gene (P53 which is genome guardian preventing cells leaving G1)
What are examples of gatekeeper tumour suppressor genes?
p53
pRb
What are examples of caretaker tumour suppressor genes?
BRCA
MMR
What are examples of pro-apoptotic genes?
Bax
What are the types of DNA damage?
- oxidation of bases (reactive oxygen species = DNA strand interruptions)
- alkylation of bases (methylation)
- hydrolysis of bases (deamination, depurination, depyrimidination)
- Bulky adduct formation
- mismatch of bases (DNA replication errors)
What are the clinical features of benign tumours?
- slow growing but progressive (rare mitotic figures)
- non-invasive
- non-metastasising
- well differentiated
What are the clinical features of malignant tumours?
- fast growing
- numerous and abnormal
- ulcerate of surface
- local invasion
- may metastasise
- may see weight loss, anorexia, anaemia
