子宫颈癌组织中抑癌基因DNA甲基化的检测

目的 通过分析宫颈上皮内瘤变（CIN）和宫颈癌组织中p16、CDH1、RASSF1A和TIMP3基因DNA甲基化的变化情况,探讨其在宫颈癌发生中的意义。方法 用甲基化特异性聚合酶链反应技术（MSP）对CINI组（40份）、CINⅡ～Ⅲ（40份）、宫颈癌组（40份）病变组织中p16、CDH1、RASSF1A和TIMP3基因DNA甲基化程度进行检测。另取正常宫颈组织20份作为对照组。结果（1）对照组中p16、CDH1、RASSF1A和TIMP3基因的DNA甲基化阳性率均为0。（2）p16和CDH1基因的DNA甲基化阳性率,CIN11～m组（分别为22％、35％）明显高于CINI组（分别为2％、5％,P〈0．05）;RASSF1A和TIMP3基因的DNA甲基化阳性率,CINⅡ～Ⅲ组（分别为12％、15％）虽高于CINI组（均为2％）,但差异无统计学意义（P〉0．05）。（3）宫颈癌组p16（40％）、CDH1（58％）、RASSF1A（20％）和TIMP3（35％）基因的DNA甲基化阳性率虽均高于CINⅡ-Ⅲ组,但差异无统计学意义（P〉0．05）。（4）宫颈癌组p16、CDH1、RASSF1A和TIMP3基因的DNA甲基化阳性率均高于CINI组,差异有统计学意义（P〈0．05）。（5）上述基因的DNA甲基化的总阳性率（即任何一个基因出现甲基化即为阳性）,宫颈癌组（90％）明显高于CINⅡ～Ⅲ组（55％,P〈0．05）,且此两组均明显高于CINI组（8％,P〈0．05）。结论 随着从宫颈不典型增生向浸润癌的进展,p16、CDH1、RASSF1 A和,TIMP3基因的DNA甲基化阳性率明显升高,提示抑癌基因的DNA甲基化在宫颈癌发生、发展中起着一定作用,可能成为判断宫颈癌发生、发展的重要指标。

Clinical significance of detection of tumor suppressor genes aberrant methylation in cervical carcinoma tissue

OBJECTIVE: To investigate the change of aberrant methylation of p16, CDH, RASSF1A and TIMP3 in cervical carcinoma and their significance in cervical carcinoma. METHODS: Using the bisulfite-modification technique and methylation-specific PCR (MSP), we examined the aberrant promoter hypermethylation patterns of 4 tumor suppressor genes (p16, CDH1, RASSF1A, TIMP3) in 140 samples of cervical intraepithelial neoplasia (CINI, n = 40), CINII-III (n = 40), cervical carcinomas (CC, n = 40), and normal cervical tissue as a control group (n = 20). RESULTS: (1) Methylation was completely absent in control tissues. (2) Significant differences between CINII-III group and CINI group were detected for p16 and CDH1 (22% vs 2%, P < 0.05; 35% vs 5%, P < 0.05), while there were no significant differences between the two groups for RASSF1A and TIMP3 (12% vs 2%, P > 0.05; 15% vs 2%, P > 0.05). (3) The presence of methylation of p16 (40%), CDH1 (58%), RASSF1A (20%) and TIMP3 (35%) in CC were higher than the corresponding CINII-III group, but with no significant differences (P > 0.05). (4) Significant differences between CC and CINIfor p16, CDH1, RASSF1A and TIMP3 genes (P < 0.05) were observed. (5) Methylation for at least one gene was a frequent event. These figures in CC 90% (36/40) were significantly different from CINII-III 55% (22/40; P < 0.05). In comparison between CINI8% (3/40) and CC and CINII-III, these figures were significantly different (P < 0.05). CONCLUSIONS: Among the four genes, p16, CDH, RASSF1A and TIMP3, there is a significant trend for increased methylation with increasing degree of histopathological change. It suggests that the aberrant methylation of tumor suppressor genes plays a role during cervical cancer development. This may help identify women at increased risk for or cancer development and progression.