Cancer pathobiology Flashcards
Semester 1 year 1
What is cancer?
A disease of aberrant cell proliferation + differentation
In the debate of nature vs nurture, which is more significant?
Nurture - environmental influences
What environmental influences can increase risk of cancer?
-infection
-diet
-noxious substances
How can infection increase the risk of cancer?
-sarcoma virus encodes a hyperactive form of a human tyrosine kinase gene - can lead to sarcoma
-vaccination programmes reduce risk of transmission
-non viral infections e.g mould can cause cancer
How can diet increase the risk of cancer?
-obesity
-alcohol consumption
-lack of exercise
How can noxious substances increase the risk of cancer?
-if asbestos breathed in, can result in rare cancer that’s induced specifically in response to asbestos
-smoking
What is the most significant environmental influence?
-most cancer cases caused by smoking
-then obesity + diet
On a genetic level, what is cancer a consequence of?
Chromosomal change
Describe the experiment conducted on cells with chronic myeloid leukaemia (CML)
-differences in chromosome 22 in normal cells + cells with CML
-a chromosomal translocation underlies CML - end of chromosome 9 swapped with chromosome 22
-use fluorescent in situ hybridisation - create a small DNA sequence that recognises complementary sequence to show location of specific DNA region
What does the translocation that underlies CML result in?
Fusion of ABL + BCR genes
What is ABL and why is it bad for it to be fused with BCR?
-it’s a positive regulator of cell growth
-when fused, it can’t be switched off
-leads to constant cell proliferation
What is an oncogene and what does it arise from?
-a gene with the potential to cause cancer by transforming cellular behaviour
-arises from genes involved in regulated proliferation - proto-oncogenes
What can cause proto-oncogenes to become oncogenes?
-deletion or point mutation in coding sequence
-regulatory mutation
-gene amplification
-chromosome rearrangement
Are oncogenes dominant or recessive?
Genetically dominant
Why is it a benefit for cancer-causing viruses to contain an oncogene?
Virus numbers increase from proliferating cells
