Bcl-2-related proteins, alpha-smooth muscle actin and amyloid deposits in aggressive and non-aggressive basal cell carcinomas.

Aberrant expression of bcl-gene products has been implicated in the development of non-melanoma skin cancers. Recently, altered expression of alpha-smooth muscle actin has been proposed as predictive of tumour behaviour in basal cell carcinomas. The purpose of this study was to compare the aggressive and non-aggressive basal cell carcinomas in terms of bcl-gene products and alpha-smooth muscle actin expression. Fifty excisional biopsy samples were studied by immunohistochemical technique for the differential expressions of bcl-2, bax, bcl-x and alpha-smooth muscle actin. Bcl-2, bcl-x and bax were expressed in 34 (68%), 38 (76%) and 41(82%) specimens, respectively. Immunoreactivity for alpha-smooth muscle actin was noted both in tumour nests (64%) and within the stroma (54%). There was a significant difference between aggressive and non-aggressive basal cell carcinomas in terms of bcl-2 and stromal alpha-smooth muscle actin immunoreactivity. Non-aggressive basal cell carcinomas display a concordant expression of bcl-family proteins, whereas aggressive tumours reveal a discordant pattern. An increased expression of stromal alpha-smooth muscle actin with a concomitant decrease or loss of bcl-2 expression may be highly suggestive of aggressiveness in basal cell carcinoma.