目的： 检测干细胞转录因子 SRY-Box2 基因在胃癌MKN74、MKN45细胞株及人胃癌组织标本中的mRNA表达水平与甲基化情况，分析其与胃癌发生及临床病理特征之间的相关性。 方法： 选取河北医科大学第四医院胸外科2007至2012年收治的胃癌患者86例，取癌组织原发灶及其癌旁组织；分别用5-氮杂-2′-脱氧胞苷（5-aza-2′-deoxycytidine，5-Aza-Dc）与曲古抑菌素A（trichostatin A，TSA）处理胃癌MKN74、MKN45细胞，检测甲基化与乙酰化对细胞内 SRY-Box2 mRNA表达的影响；甲基化特异性PCR（methylation specific PCR，MSP）、RT-PCR分别检测MKN74、MKN45细胞和胃癌、癌旁组织中 SRY-Box2 基因的甲基化状态及mRNA的表达情况；分析甲基化状态与临床病理特征之间的相关性和对 SRY-Box2 mRNA表达水平的影响。 结果： MKN45细胞中 SRY-Box2 基因mRNA表达呈阳性，MKN74细胞呈阴性；5-Aza-Dc处理MKN74细胞使 SRY-Box2 mRNA改变为阳性表达，而TSA处理对其无影响；MKN74细胞中 SRY-Box2 基因富含CpG岛并存在甲基化。胃癌组织中 SRY-Box2 mRNA表达缺失率（19.8% vs 7.0%；χ 2=69.073，P=0.014）、CpG岛甲基化水平（14.0% vs 1.2%；χ 2=10.069，P=0.002）显著高于癌旁组织，且两者显著相关（χ 2=50.878，P=0.000）； SRY-Box2 基因CpG岛的甲基化水平与淋巴结转移情况相关（χ 2=3947，P=0.047），与临床分期、病理学分级及浸润深度均无关（均P＞0.05）。 结论： 基因CpG岛甲基化是 SRY-Box2 基因表达下调的机制之一，并可能在胃癌的发生中发挥了一定的作用。

Objective : To determine mRNA levels and methylation status of stem cell transcription factor SRY-Box2 in gastric cancer (GC) cell lines (MKN74, MKN45) and tissue specimens in association with pathogenesis and clinicopathological features of GC. Methods: Eighty-six gastric cancer patients diagnosed in the Thoracic Surgery of the Fourth Hospital of Hebei Medical University between 2007 and 2012 were recruited. Biopsy specimens were collected from primary tumors and the corresponding adjacent tissues. The gastric cancer cell lines (MKN74, MKN45) were treated respectively with 5-aza-2’-deoxycytidine (5-Aza-Dc) and trichostatin A (TSA). Levels of CpG methylation of the SRY-Box2 promoter and SRY-Box2 mRNA were assessed by methylation specific PCR (MSP) and RT-PCR, respectively, in MKN74, MKN45 cells after drug treatments and in biopsy specimens. The relevance of SRY-Box2 gene methylation to and clinicopathological features of the cancer and to changes in RY-Box2 mRNA abundance was analyzed. Results: SRY-Box2 mRNA was detected in MKN45 cells but not in MKN74 cells. Treatment with 5-aza-2’-deoxycytidine (5-Aza-Dc, a demethylation agent) significantly increased SRY-Box2 mRNA abundance but trichostatin A (TSA) had no effect inMKN45 cells. Hypermethylation of SRY-Box2 gene containing a CpG island was observed in MKN74 cells. The frequency of expression loss of the SRY-Box2 gene (19.8% vs 7.0%; χ 2=69.073, P=0.014) and the level of hypermethylation (14.0% vs 1.2%；χ 2=10.069, P=0.002) were all significantly higher in the cancer tissue as compared with adjacent non-cancerous tissues.and hypermethylation was significantly correlated with expression loss in the SRY-Box2 gene (χ 2=50.878,P<0001). Furthermore, SRY-Box2 gene hypermethylation status was also correlated with lymph node metastasis (χ 2=3947, P=0.047), but not with clinical stage, pathological grade and depth of invasion ( P>0.05). Conclusion: CpG hypermethylation may be one of the mechanisms responsible for the expression loss of the SRY-Box2 gene and may play some role in the pathogenesis of gastric cancer.

河北自然科学基金资助项目（No. H2013206315）