Week 6 Part 1 - Tumor Suppressor Genes

A set of flashcards reviewing key concepts related to tumor suppressor genes and their roles in cancer biology.

What are tumor suppressor genes (TSGs)?

Genes that act as stop signals to uncontrolled growth and can inhibit the cell cycle.

What occurs when both copies of a tumor suppressor gene are inactivated?

The inhibitory signal is lost, which may result in unregulated cell growth.

What is the loss of heterozygosity?

It refers to the loss of the remaining wild-type allele after a mutation occurs in one copy of a TSG.

What does the RB1 protein do in the cell cycle?

The RB1 protein regulates the cell cycle by inhibiting the G1 to S phase transition.

What is the two-hit hypothesis?

It explains hereditary syndromes that predispose individuals to cancer through germline mutations.

What are BRCA1 and BRCA2 genes associated with?

They are linked to breast and ovarian cancer susceptibility.

What role does PTEN play in tumor suppression?

PTEN is a phosphatase that antagonizes the PI3K pathway, inhibiting cell proliferation and promoting apoptosis.

What is Cowden Syndrome?

A cancer predisposition syndrome caused by mutations in the PTEN gene, leading to uncontrolled cell division and tumors.

How does the loss of RB1 function affect cell growth?

Complete loss of RB1 function drives uncontrolled cell division by removing cell cycle regulation.

What does p53 do in response to DNA damage?

p53 activates cell cycle arrest, DNA repair, apoptosis, and inhibition of angiogenesis.

What is MDM2's role in regulating p53?

MDM2 is a ubiquitin ligase that regulates p53 by targeting it for degradation.

What is the significance of the p53-MDM2 feedback loop?

It is auto-regulatory: p53 stimulates MDM2 production, which degrades p53, maintaining low p53 levels.

What can activate p53?

Stress signals such as DNA damage, oncogenic activation, and cellular distress can activate p53.