In experimental skin carcinogenesis in mice, application of a single dose of a mutagenic hydrocarbon produces no visible tumors unless followed by repeated applications of phorbol ester, which then yields papillomas. Phorbol ester itself is non-mutagenic. In this model, phorbol ester acts as:
- A An initiator
- B A complete carcinogen
- C A promoter ✓
- D A co-carcinogen
Correct answer: C. A promoter
Explanation
Promoters induce clonal expansion of initiated cells through stimulation of proliferation without causing DNA damage themselves. Phorbol esters activate protein kinase B and drive proliferation of the mutagen-altered cells. Initiation requires a single exposure to a genotoxic agent and is irreversible; promotion requires repeated exposure and is reversible if stopped early. A complete carcinogen possesses both initiating and promoting capacity, which phorbol ester lacks because it is non-mutagenic.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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