Expression of the apoptosis inhibitor, survivin, in nonmelanoma skin cancer and gene targeting in a keratinocyte cell line.

The recently described apoptosis inhibitor survivin is expressed in many human cancers, thus potentially contributing to disease progression and resistance to therapy. Its potential role in nonmelanoma skin cancer is unknown. By immunohistochemistry, survivin was expressed in 81% (17 of 21) of basal cell carcinomas (BCC) of both nodular and morpheaform subtypes, and in 92% (24 of 26) of cutaneous squamous cell carcinomas (SCC). Survivin was also expressed in 19 premalignant lesions of Bowen's disease (SCC in situ) and hypertrophic actinic keratosis (HAK), suggesting that its appearance occurs early during keratinocyte transformation. Survivin expression was detected by Western blotting in a model keratinocyte cell line, HaCat. Transfection of HaCat cells with green fluorescent protein (GFP)-conjugated survivin antisense or GFP-conjugated survivin dominant negative mutant (Cys84Ala) resulted in spontaneous apoptosis in the absence of other genotoxic stimuli. In GFP-conjugated survivin antisense transfectants, a decreased level of endogenous survivin was confirmed by flow cytometry. This was associated with a five-fold increase in the sub-G0/G1 fraction corresponding to apoptotic cells and a decrease in proliferating cells with 4N DNA content. These data demonstrate that apoptosis inhibition by survivin may participate in the onset and progression of both BCC and SCC, and suggest that therapeutic targeting of survivin may be beneficial in patients with recurrent or advanced disease.