Bax/bcl-2: Cellular modulator of apoptosis in feline skin and basal cell tumours

Bcl-2 and bax are two memebers of the BCL-2 gene family that play a promine nt role in the regulation of apoptosis. Bax and bcl-2 expression were exami ned immunohistochemically in normal (healthy) feline skin and in 24 benign feline cutaneous basal cell tumours. The tumours were also examined for cel lular proliferation by measurement of reactivity for the proliferation mark er Ki-67, and for apoptosis by in-situ labelling for fragmented DNA. Bcl-2 was detected in normal basal epithelium and in 23 of 24 basal cell tumours. Bax was detected in both basal and suprabasal epithelium, but in only seve n of 24 tumours. For tumours that expressed both bax and bcl-2, the bax:bcl -2 ratio was low. Neither bax nor bcl-2 expression was detected in 14 felin e cutaneous squamous cell carcinomas. Basal cell tumours showed modest cell ular proliferation (median, 17.5% Ki-67- reactive cells), but few (less tha n 1%) apoptotic cells. The slow, indolent growth of feline cutaneous basal cells in these benign skill tumours may be a response at least in part, to opposing regulatory expressions of bcl-2 and bax. (C) 2001 Harcourt Publish ers Ltd.