Ingredient in red peppers inhibits prostate cancer in laboratory studies

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Apr 5 2006

Capsaicin is the pungent ingredient in red peppers and is presently used as a topical pain reliever. Now, a new study shows it may be justified to evaluate capsaicin for inhibiting prostate cancer (CaP) in patients.

Dr. Mori and associates from UCLA, Los Angeles and Keio University, Tokyo, Japan report in the March 2006 issue of Cancer Research that capsaicin killed CaP cells in vitro. To study this, they used LNCaP cells that express the androgen receptor (AR) and PC3 cells which do not express AR.

Addition of capsaicin to the LNCaP cells downregulated the expression of PSA and AR. Molecular assays showed that capsaicin inhibited the ability for synthetic androgen to activate the promoter in the PSA gene, even when additional AR was exogenously introduced into the LNCaP cells. This suggests that the effect of capsaicin is on PSA transcription directly, and not solely via downregulation of AR expression.

Capsaicin inhibited the transcription factor NF- k B by blocking the tumor necrosis factor- a degradation of the inhibitory protein I k B a , which normally maintains NF- k B in an inactive state in the cytoplasm.

Androgen insensitive PC3 cells injected into mice grew tumors that weighed on average 373mg at 4 weeks. Capsaicin given orally three times per week decreased the tumor weight to an average of 203mg.

These data suggest that capsaicin can inhibit the growth of androgen sensitive and insensitive CaP, and the effect in androgen sensitive cells is not directly through decrease expression of AR. It establishes a rationale for a clinical trial of capsaicin in CaP.

By Christopher P. Evans, MD

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