S100A6对胃癌细胞侵袭转移的调控机制研究

Regulation mechanism study of S100A6 on invasion and metastasis in gastric cancer

目的探讨S100A6过表达对胃癌细胞侵袭转移的调控机制。方法收集1995年1月至2001年12月间经病理确诊的166例胃癌标本及其对应的癌旁组织、肝转移组织和淋巴结转移组织标本，采用免疫组织化学染色法检测标本中S100A6蛋白的表达情况及其与临床病理因素的关系：通过ChIP—Chip方法检测胃癌细胞株KAT03中S100A6可能调控的下游因子；将S100A6基因转染入胃癌细胞株AGS，通过细胞侵袭实验、RTQ—PCR方法分别检测转染组、阴性对照组和空白对照组中细胞的侵袭能力和侵袭转移相关因子CDK5和FLJ12438的mRNA表达。结果S100A6蛋白在癌旁组织细胞质中偶有低表达；而在胃癌、肝及淋巴结转移灶组织的肿瘤细胞质和（或）细胞核中均有高表达，且在侵袭边缘的肿瘤细胞的细胞核中表达较高，其高表达率为分别为67．5％（112／166）、92．9％（26／28）和100％（30／30）。S100A6表达与肿瘤浸润深度、淋巴结转移、脉管癌栓、远处转移及TNM分期有关（均P〈0．05）。S100A6可能作用于26个细胞侵袭转移有关基因的启动子部位。SIOOA6转染组的过膜细胞数为31．3±5．5，多于阴性对照组的7．7±1．5和空白对照组的9.3±2．1，差异有统计学意义（均P〈0．05）。CDK5mRNA在转染组中的表达水平显著高于阴性对照组和空白对照组（均P〈0．05），而FLJ1243mRNA在转染组中的表达水平与另外两组的差异则无统计学意义（均P〉0．05）。结论S100A6可能通过调控下游侵袭相关因子如CDK5的表达，进而影响胃癌细胞的侵袭转移等恶性生物学行为。

Objective To detect the expression of S100A6 in gastric cancer, and to investigate the regulation mechanism of S100A6 in invasion and metastasis of gastric cancer. Methods Expression of S100A6 protein in gastric cancer specimens, tissue adjacent to cancer, liver and lymph node metastasis tissue specimens was detected by immunohistochemical staining in 166 patients with gastric cancer from January 1995 to December 2001. Their association with clinicopathological factors was analyzed. Chromatin Immunoprecipitation-chip was used to detect the downstream factors potentially regulated by S100A6 in gastric cancer cell lines KATO3. SI00A6 gene was transfected into gastric cancer cell line AGS, and cell invasion experiment and real time Q-polymerase chain reaction （RT Q-PCR） were used to detect the cell invasive ability and the mRNA expression of invasion-related factors （CDK5 and FLJ12438） in transfection group, negative control group and blank control group, respectively. Results Low expression of S100A6 protein was found in cytoplasm of peritumoral tissues. In gastric cancer, liver and lymph node metastasis tissues, S100A6 protein expression was up-regulated in cytoplasm and （or） nuclei, especially in the tumor cells of invasive edge. The expression rates of gastric cancer, liver and lymph node metastasis tissues were 67.5%（112/166）, 92.9% （26/28） and 100% （30/30） respectively. The high expression of S100A6 was associated with tumor local invasion, lymph node metastasis, cancer embolus, distant metastasis and TNM stages（all P〈0.05）. The transmembrane cell number was 31.3±5.5 in the S100A6 transfection group, significantly higher than that in negative control group （7.7± 1.5） and blank control group （9.3±2.1）（both P〈0.05）, indicating an increase of cell invasion after SIOOA6 transfection. In transfection group, CDK5 mRNA expression was significantly higher than that in negative control group and blank control group （P〈0.05）. While FLJ1243 mRNA expression was similar among the three groups（P〈0.05）. Conclusion S100A6 may affect the malignant biological behavior of gastric cancer cells by regulating the expressions of down-stream invasion- associated factors, such as CDK5.