Lecture 4 Oncogene/Protooncogene/Tumor suppresing gens

Question 1

What is oncogenes

Answer 1

-Genes with potential to cause cancer
-Altered forms of normal genes (proto-oncogenes) that are mutated/overexpressed
-Activated via mutation, amplification, translocation
-Promote cell proliferation
-Inhibit apoptosis
-Enhance angiogenesis for tumor growth and progression

Question 2

What is proto oncogene

Answer 2

Start as normal genes that encode proteins involved in:
Cell signal, growth factor production, cell cycle regulation, inhibition of apoptosis

Question 3

what is tumor suppressor gene

Answer 3

Prevent excessive cell division
If this function is lost -> cancers

Question 4

P53 gene

Answer 4

Normal Function
Inhibits cell cycling
To allow cell time to repair damages

Damage leads to uncontrolled cell growth and tumor progression
Makes cancer treatment difficult
Chemo/Radiation -> p53 accumulates -> p53 signals apoptosis

***Cancer cells without a functional p53 gene are therefore resistant to chemotherapy/radiation

Question 5

Rb gene

Answer 5

Normal Function
Block cell division by inhibiting transcription factors (specifically initiate cell cycle block)

Damage or inactivation
Removes the restraint on cell division

Question 6

BRCA1 gene

Answer 6

Normal Function
Regulate p53 functions (that inhibit cell cycling)
Transcription regulation, cell cycle control by DNA double strand repair pathway.

Damage or inactivation
Increased risk for breast, ovarian, and prostate cancers
Platinum based chemotherapies effective in treatment

family Hx of defective gene =50%^ chance of getting breast cancer

Question 7

BRCA2 gene

Answer 7

Normal Function
DNA repair, transcription regulation, cell cycle control

Damage or inactivation
Increased risk for breast, ovarian, and prostate cancers
Platinum based chemotherapies effective in treatment