pERK Expression in Skin Squamous and Basal Cell Carcinoma

Abstract

Objective: Curcumin, a naturally occurring bioactive food compound has been shown to inhibit progression of cutaneous SCCa, possibly via inhibition of the MEK/ERK signaling pathway. In our effort to selectively inhibit cutaneous SCCa, we hypothesize that the MEK/ERK pathway is over-expressed in SCCa, suggesting a novel target for curcumin.

Method: Normal human skin (N = 28), BCCa (N = 12), and SCCa (N = 11) were analyzed for pERK (Thr202/Tyr204) expression by IHC. Tumor sections were subjectively scored from 0 to 2+ (none, weak or focal, strong) based on the intensity of the stain, and compared by Chi Square analysis.

Results: All SCCa (N = 11) and only 5/12 (54%) BCC stained positive for pERK. Tumors expressed more pERK than normal skin χ² (2, N = 51) = 26.37, P < .001, and differed by tumor type, χ² (1, N = 23) = 6.77, P = .009. Tumor type significantly predicted pERK staining, b = .67, t(20) = 2.39, P = .027, and explained a significant proportion of variance in pERK scores, R² = .33, F(3, 20) = 3.33, P = .04, whereas age (P = .59) and gender (P = .17) did not explain the variance in pERK staining.

Conclusion: The MEK/ERK pathway appears to be over-expressed in SCCa compared with the more common BCCa. As curcumin has been shown to slow progression of cutaneous SCCa and inhibit pERK expression, the MEK/ERK pathway may prove a key biomarker in developing pharmaceutical agents that prevent SCCa tumor growth.