乳头状甲状腺癌TSHR基因转录表达和启动子区甲基化研究

Transcription and promoter hypermethylation of thyroid stimulating hormone receptor gene in human papillary thyroid carcinoma

目的观察抑癌基因促甲状腺激素受体(TSHR)在乳头状甲状腺癌(PTC组)中的表达,分析其启动子甲基化与肿瘤发生的关系。方法选择50例PTC和32例良性甲状腺肿瘤(对照组,包括20例结节性甲状腺肿,12例甲状腺腺瘤)患者,对两组患者手术获取的标本提取RNA后,反转录为cDNA,进行PCR检测TSHR基因的表达情况;运用甲基化特异性PCR(MSP)检测上述组织中TSHR基因启动子区甲基化的情况。结果PTC组患者中有34例(68%)TSHR基因启动子发生甲基化,16例(32%)TSHR基因mRNA表达缺失;对照组患者中有7例(21.9%)TSHR基因启动子发生甲基化,4例(12.5%)TSHR基因mRNA表达缺失。PTC组织TSHR基因启动子甲基化率及TSHR基因mRNA表达缺失率均显著高于对照组(χ2值分别为16.61和4.02,P<0.05)。34例发生了TSHR基因启动子甲基化的PTC患者中,有14例(41.2%)TSHR mRNA表达缺失;16例未发生甲基化的PTC患者中,2例(12.5%)发生了mRNA表达缺失,二者mRNA表达缺失率差异有统计学意义(χ2=4.11,P<0.05)。TSHR基因mRNA在乳头状甲状腺癌中的表达明显低于对照组织(t=3.86,P<0.05)。结论PTC患者TSHR基因启动子甲基化发生率显著高于良性甲状腺肿瘤患者,而TSHR基因mRNA的表达则较良性甲状腺肿瘤降低;推测TSHR基因启动子甲基化可能与PTC的发生、发展相关。

Objective To study the mRNA expression of the tumor suppressor gene thyroid stimulating hormone receptor （TSHR） gene in papillary thyroid carcinoma （PTC） and the correlation between aberrant promoter methylation of TSHR gene and the tumorigenesis of PTC. Methods RT-PCR was used to detect the mRNA expression of TSHR gene in 50 PTC cases, 20 cases of nodular goiter and 12 cases of thyroid adenoma tissue. The status of TSHR gene promoter methylation was determined using methylation-specific PCR technique. Results Of the 50 PTC patients, 34 （68%） were found to have hypermethylation of TSHR gene promoter region, as compared to 7 out of the 32 control patients （21.9%） positive for TSHR gene promoter hypermethylation, suggesting a significantly higher rate of TSHR promoter methylation of in PTC patients than in the control patients （χ2=16.61, P0.05）. Of the 34 PTC patients with TSHR promoter methylation, 14 （41.2%） showed the absence of TSHR mRNA expression; in the 16 PTC patients without TSHR promoter methylation, only 2 （12.5%） were negative for TSHR mRNA expression, showing a significant difference in the rate of negative TSHR mRNA expression with regard to TSHR promoter methylation. The PTC patients had a significantly lower TSHR mRNA expression than the control patients （χ2=4.02, P0.05）. Conclusion Methylation of TSHR gene in the promoter region is a common molecular event, which might be associated with the tumorigenesis and progression of human PTC.