Immunohistochemical determination of the P15^INK4b protein expression in cutaneous squamous cell carcinoma

The tumor suppressor gene p15^INK4b is a cyclin-dependent kinase inhibitor, in which its inactivation has been determined in primary tumors and in several tumor-derived cell lines. The precise role of p15^INK4b protein expression in cutaneous squamous cell carcinoma (SCC) is currently not known. In a previous study, we have shown the frequent occurrence of allelic imbalance/loss of heterozygosity in cutaneous SCC using two microsatellite markers flanking the p15^INK4b gene. This study is a continuation of our previous study and aims to determine the possible role of p15 ^INK4b protein expression in the genesis of cutaneous SCC. P15 ^INK4b protein expression was determined using immunohistochemical approach in 107 cases of cutaneous SCC tissue arrays and 19 cases of normal human skin tissues. The expression of p15^INK4b was significantly reduced in the cutaneous SCC cases as compared with normal human skin (p = 0.017 and p < 0.05). However, there were no significant relationship between clinicopathologic variables of the patients (age, sex and tumor grade) and p15^INK4b protein expression. The absence of p15^INK4b expression in the majority of tissue microarray cores of cutaneous SCC indicated that p15^INK4b could possibly be involved in the pathogenesis of cutaneous SCC.