Which of the following process does NOT contribute to conversion of a proto-oncogene to oncogene?
Which of the following process does NOT contribute to conversion of a proto-oncogene to oncogene?
Select an option to attempt
Correct Answer: Option B
Explanation
Proto-oncogene → oncogene transformation requires gain-of-function mechanisms: (1) Activating point mutations — e.g. KRAS G12V/D, BRAF V600E; constitutively active; (2) Gene amplification — overexpression; e.g. HER2/ERBB2 amplification in breast cancer; (3) Chromosomal translocation — fusion with a strong promoter or creation of chimeric oncogene (e.g. BCR-ABL in CML, EML4-ALK in NSCLC). A DE-ACTIVATING (loss-of-function) mutation in a PROTO-ONCOGENE would REDUCE or eliminate its activity — making it less oncogenic, not more. (Loss-of-function mutations in TUMOUR SUPPRESSOR genes, e.g. TP53, RB1, drive cancer.) Therefore 'de-activating mutation in proto-oncogene' does NOT convert it to an oncogene.