分泌型卷曲相关蛋白4在不同DNA错配修复功能状态Ⅱ期肠癌中的表达及意义

目的探究分泌型卷曲相关蛋白4（SFRP4）在DNA错配修复（MMR）功能正常与MMR功能缺陷的Ⅱ期结肠癌中的表达及意义。方法收集新鲜的Ⅱ期结肠癌组织标本，并根据MMR 状态分为pMMR 和dMMR 组。利用Affymetrix HumanoeLncRNA 基因芯片检测两组不同MMR状态结肠癌组织中差异表达的mRNA情况。通过q-PCR和Westernblot 技术检测dMMR和pMMR肠癌组织、细胞株中SFRP4的表达并分析两组间表达差异情况；通过免疫组化技术检测增殖标志物Ki-67的表达并分析SFRP4与Ki-67表达的相关关系。利用HCT116细胞株，干扰SFRP4的表达，通过流式细胞术检测干扰SFRP4前与干扰后HCT116细胞株的凋亡率并分析其差异。结果PCR和Western blot的结果提示SFRP4在dMMR状态的肠癌组织、细胞株中的表达明显高于pMMR的肠癌组织（P=0.014）、细胞株（P=0.0079），免疫组化结果提示SFRP4与Ki-67蛋白在肠癌组织的表达呈负相关关系（P=0.041）。siRNA干扰SFRP4的表达后HCT116细胞株凋亡率下降，包括早期凋亡（P=0.003）和晚期凋亡率（P=0.024）。结论SFRP4在dMMR型肠癌表达较pMMR型表达增高，促进肠癌细胞凋亡、抑制增殖，可能有助于改善MMR缺陷型Ⅱ期肠癌预后。

Expression of secreted frizzled-related protein 4 in DNA mismatch repair-deficient andmismatch repair-proficient colorectal cancers

Objective To investigate the expressions of secreted frizzled-related protein 4 (SFRP4) in stage II DNA mismatchrepair-deficient (dMMR) and mismatch repair- proficient (pMMR) colorectal cancers and explore their clinical significance.Methods We collected fresh stage II colon cancer tissues with different MMR status detected by immunohistochemistry (IHC).The differentially expressed mRNAs between dMMR and pMMR tumors were identified by Affymetrix Human oeLncRNAgene chip, and the expression of SFRP4 in these cancer tissues and in colorectal cancer cell lines were detected using Westernblotting and real- time quantitative PCR. The apoptosis rates of HCT116 cells with and without siRNA- mediated transientSFRP4 knockdown were determined using flow cytometry. We further investigated the expression pattern of Ki-67 and itscorrelation with SFRP4 expression. Results Compared with pMMR colon cancer tissues or cells, both dMMR colon cancertissues (P=0.014) and cells (P=0.0079) showed significantly increased expression of SFRP4, which was in negative correlationwith Ki-67 (P=0.041). In HCT116 cells, transient SFRP4 knockdown resulted in decreased cell apoptosis, including both earlyapoptosis (P=0.003) and late apoptosis (P=0.024). Conclusion Up-regulation of SFRP4 in dMMR stage II colon cancer promotesapoptosis and inhibits proliferation of the cancer cells, and may improve the prognosis of dMMR colon cancer.