Oncogene

Oncogene — oncology-focused definition

An oncogene is a mutated or overexpressed form of a normal gene (proto-oncogene) that drives uncontrolled cell growth, proliferation, and survival, contributing to cancer development.

Key features:

• Results from gain-of-function alterations, such as:
  • Point mutations (e.g., RAS)
  • Gene amplification (e.g., MYC, HER2)
  • Chromosomal translocations (e.g., BCR-ABL, MYC t(8;14))
• Acts in a dominant manner—alteration of one allele is sufficient for oncogenic effect.

Clinical significance (for oncology pharmacists):

• Oncogenes often encode drug-targetable proteins (kinases, receptors, signaling molecules).
• Presence of an oncogenic driver can:
  • Predict response or resistance to targeted therapy
  • Influence prognosis
  • Determine treatment selection and sequencing

Examples:

• RAS → constitutive MAPK signaling
• MYC → dysregulated transcription and cell cycle progression
• HER2 → enhanced growth factor signaling
• BCR-ABL → constitutive tyrosine kinase activity (CML)

Key takeaway:

Oncogenes are central drivers of malignancy and form the molecular basis for precision oncology and targeted cancer therapy.