Expression of Yes-associated protein in colorectal carcinoma and its effect on tumor cell proliferation

Objective To evaluate the expression of Yes-associated protein (YAP) in colorectal carcinoma and analyze its influence on tumor cell proliferation.Methods The expressions of YAP in 94paired colorectal carcinomas and pericancerous normal tissues were detected by using immunohistochemistry method.The expressions of YAP in colorectal carcinoma cell line HCT116 were inhibited with a YAP-spe-cific siRNA.Cell proliferation was then determined by methyl thiazolyl diphenyl-tetrazolium bromide (MTT) assay.Results The positive rate of YAP in colorectal carcinomas was significantly higher than that in pericancerous normal tissues [69.1％ (65/94) vs 22.3 ％ (21/94),P ＜ 0.001].The expression of YAP was associated with tumor Node Metastasis(TNM) stage and lymph node metastasis(P ＜0.05),but not associated with gender,age,tumor location and histological grade(P ＞0.05).After YAP-specific siR-NA was transfected into HCT116 using lipofectamine,the expression of YAP mRNA and protein in the experimental group were reduced by (78.2 ±2.1)％ and (81.7 ± 1.5)％,respectively,with a statistically significant difference (t =67.55,91.601,P ＜0.01).The growth of HCT116 was significantly inhibited and the reduced rate of cell proliferation was (28.1 ± 1.6) ％,(34.7 ± 2.4) ％ and (24.7 ± 1.2) ％ at the time point of 48 h,72 h and 96 h,respectively.Conclusions Expression of YAP was upregulated in colorectal carcinomas and downregulation of YAP expression could inhibit growth of colorectal carcinoma cells.YAP can be used as a new candidate target for diagnosis and treatment of a colorectal carcinoma. Key words: Colorectal neoplasms/pathology;  Cell proliferation;  RNA interference