结直肠癌组织多基因甲基化的检测及其临床意义

目的： 检测结直肠癌组织中脾酪氨酸激酶（Syk）、E-钙黏附素（E-cadherin,CDH1）和组织金属蛋白酶抑制因子-3(TIMP-3)多基因甲基化水平，并探讨多基因甲基化在结直肠癌发病机制中的作用与复发转移和术后预后的关系。方法: 采用巢式甲基化特异性PCR(n-MSP)方法检测120例结直肠癌肿瘤组织Syk的甲基化水平, 及其中100例结直肠癌肿瘤组织CDH1和TIMP-3的甲基化水平。结果: 1个及以上基因共甲基化率为74%，2个基因同时甲基化率为21%， 3个基因共同甲基化为8%。3个基因同时甲基化阳性与淋巴结转移无关（2=0.725，P>0.05）；CDH1基因甲基化与肝肺转移显著相关（2=6.938，P<0.01），Syk和TIMP-3基因甲基化与肝肺转移无关；Syk甲基化、TIMP-3甲基化、CDH1及TIMP-3同时甲基化是结直肠癌术后生存的相对危险因素，而3个基因同时甲基化则是非相对危险因素。结论: 结直肠癌组织中存在多基因共同甲基化率，多基因共同甲基化在结直肠癌发病机制、侵袭复发机制及影响预后生存中并非必需条件。

Methylation status of multiple genes in colorectal cancer tissues and its clinical significance

AIM: The aim of the present study was to detect the methylation status of multiple genes (Syk, CDH1 and TIMP-3) in colorectal cancer (CRC) tissues, to investigate the roles in the pathogenesis of CRC, to investigate whether methylation of multiple genes was associated with recurrence and metastasis of CRC, and to evaluate its ability to predict the prognosis of CRC. METHODS: Nested methylation-specific PCR (n-MSP) were used to detect methylation status of spleen tyrosine kinase (Syk) from 120 CRC tissues and the methylation status of CDH1 and tissue inhibitor of metalloproteinase-3 (TIMP-3) from 100 CRC tissues. RESULTS: We found that methylation in one or more genes, co-methylation in two genes and three genes were detected in 74%, 21%, and 8% of CRC tissues. No significant correlation between three genes co-methylation and lymph node metastasis (2=0.725，P>0.05) was observed. The methylation of CDH1 gene, but not Syk or TIMP-3 gene, was significantly related with liver and lung metastasis of CRC (2=6.938，P<0.01). The methylation of Syk or TIMP-3, and co-methylation of CDH1 and TIMP-3 were risk factors in the prognosis of colorectal cancer after surgical treatment, and three genes co-methylation was not a risk factor. CONCLUSION: Our results indicate that methylation of multiple genes exists in CRC tissues. The methylation of multiple genes is not a necessary factor in the pathogenesis, metastasis and recurrence of CRC, and also it is not a necessary prognostic factor in CRC.