Oncogenes and Cancer

Flashcards covering key concepts related to oncogenes and their role in cancer.

What is an oncogene?

A mutated or overexpressed proto-oncogene that drives cancer.

What kind of mutation creates an oncogene?

Gain-of-function; only one allele needs to be mutated (dominant).

What do oncogenes promote in cancer?

Cell growth, proliferation, and survival.

Name 5 key oncogenes and the cancers they’re linked to.

HER2 (breast), RAS (pancreatic, colon, lung), EGFR (lung, colorectal), MYC (lymphoma, breast), BCR-ABL (CML).

What is a proto-oncogene?

A normal gene involved in cell growth/division that can become an oncogene.

Name 4 mechanisms that convert proto-oncogenes to oncogenes.

Point mutation, gene amplification, translocation, viral integration.

What is insertional mutagenesis?

Viral DNA integration activates proto-oncogenes.

What pathway is activated by EGF?

The MAPK pathway.

What are the steps of EGF signaling?

EGF binds EGFR → Dimerization → Autophosphorylation → RAS → RAF → MEK → MAPK → Transcription → Cell division.

What happens if RAS, RAF, or EGFR are mutated?

Constant activation of signaling and uncontrolled growth.

Why is RAS considered the most mutated oncogene?

Found in 90% of pancreatic cancers and others like colon, lung, thyroid.

What makes RAS oncogenic?

Mutation keeps it in a permanently 'on' state.

What type of gene is MYC?

A transcription factor oncogene.

What happens when MYC is overexpressed?

Leads to excessive cell growth and division.

What cancers are associated with MYC?

Lymphomas, breast cancer, lung cancer.

What is the BCR-ABL fusion?

A gene fusion from t(9;22) that creates a constant tyrosine kinase.

What cancer is BCR-ABL linked to?

Chronic Myeloid Leukemia (CML).

What drug targets BCR-ABL?

Imatinib (Gleevec).

What is the BRAF V600E mutation?

A mutation that causes constant MAPK activation.

In what cancers is BRAF commonly mutated?

Melanoma (70%), thyroid (50%), colon (10%).

What drug targets BRAF mutations?

Vemurafenib.

How do MYC and RAS cooperate in cancer?

Together, they accelerate tumor progression more than alone.

What is a Kaplan-Meier plot used for in oncology?

Shows survival differences in patients with specific mutations.

Why is understanding oncogenes clinically important?

For prevention, early detection, and targeted therapy.

Give an example of an oncogene-based therapy.

EGFR inhibitors, Imatinib (BCR-ABL), Vemurafenib (BRAF).

What is KRAS testing used for in colorectal cancer?

To predict response to EGFR-targeted treatments.

What's the outcome of EGFR therapy in KRAS-mutated cancers?

Poor response; therapy is ineffective.