Expression of protein kinase D1 and its phosphorylation at tyr463 and ser916 in squamous cell carcinoma, Bowen's disease and actinic keratosis / 中华皮肤科杂志

ABSTRACT

Objective To measure the expression of protein kinase D1 (PKD1),tyr463-phosphorylaed PKD1 (pPKD1-tyr463) and ser916-phos-phorylaed PKD1 (pPKD1-ser916) in squamous cell carcinoma (SCC),Bowen's disease (BD) and actinic keratosis (AK),and to explore their significance.Methods Fresh tissue samples were resected from lesions of patients with SCC (SCC group),BD (BD group) and AK (AK group),as well as from normal skin of healthy human controls (control group),and each group had a sample size of 10.Real-time RT-PCR was performed to measure the mRNA expression of protein kinase D1 gene (PRKD1),and Western blot analysis to determine the protein expression of PKD1,pPKD1-tyr463 and pPKD1-ser916.In addition,immunohistochemical study was conducted to determine the expression of PKD1,pPKD1-tyr463 and pPKD1-ser916 in another 50 paraffin-embedded skin samples of SCC,20 samples of BD,20 samples of AK and 10 normal skin samples.Results PRKD1 mRNA expression significantly differed among the control group (0.64 ± 0.09),SCC group (5.37 ± 1.06),BD group (2.69 ± 0.72) and AK group (2.43 ± 0.46) (F =21.37,P ＜ 0.05),and was significantly higher in the SCC,BD and AK groups than that in the control group (P ＜ 0.05),as well as in the SCC group than that in the AK and BD groups (both P ＜ 0.05).However,no significant difference in the PRKD1 mRNA expression was observed between the BD group and AK group (P ＞ 0.05).Immunohistochemical study showed that the total PKD1 protein and pPKD1-tyr463 in the SCC and BD groups were mainly expressed in the cytoplasm and cell membrane of spinous layer cells and atypical cells,and their expression rates were significantly higher than those in the AK group and control group (all P ＜ 0.01).The pPKD1-ser916 was only slightly expressed in some cancer nests of well-differentiated SCC tissues,but not in poorly-differentiated SCC,AK,BD tissues and normal skin tissues.In the SCC group,the expression rate of PKD1 increased with the increase of the pathological grade of SCC,and the PKD1 expression was positively correlated with pPKD1-tyr463 expression (rcc =0.479,P ＜ 0.05).Western blot results were consistent with immunohistochemical findings.Conclusion PKD1 and pPKD1-tyr463 may be involved in the development and differentiation of skin tumors derived from stratified squamous epithelium,and PKD1 may exert promotive effects on the formation of cutaneous SCC by activating the Tyr463 phosphorylation site.