18. Molecular Hallmarks of Cancer Cells

Question 1

what are the types of tumour suppressor genes?

Answer 1

gatekeepers

caretakers

Question 2

what is the role of gatekeepers?

Answer 2

play important roles in regulating normal growth

1. negative regulators of the cell cycle and proliferation
2. positive regulators of apoptosis
3. positive regulators of cell differentiation

Question 3

what is the role of caretakers?

Answer 3

maintain genetic stability

include DNA repair genes and those that control the accuracy of mitosis

Question 4

what effected carcinogens have on tumour suppressor genes?

Answer 4

induce molecular abnormalities in TSGs that cause reduced/lack of protein expression or inactivation of protein
need 2 hits to inactivate the TSG
epigenetic inactivation is also possible by hypermethylating the promotor gene

Question 5

examples of familial cancer syndromes caused by problems in gatekeeper genes

Answer 5

retinoblastoma
Li-Fraumeni
FAP

Question 6

examples of familial cancer syndromes caused by problems in caretaker genes

Answer 6

Li-Fraumeni
familial brest cancer
HNPCC

Question 7

what is the function of proto-oncogenes?

Answer 7

promote cell proliferation, survival, angiogenesis and negative regulation of apoptosis

Question 8

what are oncogenes?

Answer 8

mutated proto-oncogenes, with increased gene expression
only 1 copy of the gene needs tp be activated to induce a gain of function. mutated gene is dominant to the other normal parental gene

Question 9

what are the effects of oncogenes on cells?

Answer 9

increased levels of cell proliferation, survival, angiogenesis and inhibition of apoptosis

Question 10

what are the mechanisms of oncogene activation?

Answer 10

translocation of a photo-oncogene from a low transcriptionally active site to an active site
point mutation - substitution of a single base pair can alter an amino acid in the protein causing it to become hyperactive
amplification by inception of multiple copies of an oncogene

Question 11

how many genetic alterations are needed to transform a normal cell into a neoplastic cell?

Answer 11

3

Question 12

what are the hallmarks of cancer cells?

Answer 12

1. self-sufficiency in growth signals
2. insensitivity to antigrowth signals
3. tissue invasion and metastasis
4. limitless potential for replication
5. sustained angiogenesis
6. evading apoptosis