oncogene
Summary
Oncogenes are mutated or overexpressed versions of normal cellular genes (proto-oncogenes) that promote cell growth and division. When activated inappropriately, they contribute to cancer development by driving uncontrolled cell proliferation, resisting apoptosis, and enabling other hallmarks of cancer.
Detail
Oncogenes arise from proto-oncogenes, which are normal genes that regulate cell growth, differentiation, and apoptosis. Proto-oncogenes can be converted to oncogenes through several mechanisms: point mutations (e.g., RAS mutations), gene amplification (e.g., HER2/neu in breast cancer), chromosomal translocations (e.g., BCR-ABL in CML), or viral insertion. Key oncogenes include RAS (signal transduction), MYC (transcription factor promoting cell cycle progression), p53 (though typically a tumor suppressor, gain-of-function mutations can act oncogenically), HER2/neu (growth factor receptor), and BCR-ABL (tyrosine kinase). Oncogenes typically act in a dominant fashion - only one mutated copy is needed to contribute to transformation. They work in conjunction with tumor suppressor gene inactivation to drive the multi-hit model of carcinogenesis. Understanding specific oncogenes has led to targeted therapies like imatinib for BCR-ABL+ leukemias and trastuzumab for HER2+ breast cancers.
Sources
- Robbins and Cotran Pathologic Basis of Disease
- First Aid for the USMLE Step 1
- Molecular Biology of the Cell (Alberts)
- The Biology of Cancer (Weinberg)
- Pathoma
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.