胃癌组织CDKN2A基因座p14ARF基因变异及意义

目的:探讨胃癌组织p14^ARF基因变异及其意义。方法: 应用PCR、PCR-SSCP、PCR甲基化分析法和RT-PCR分别检测48例胃癌及癌旁组织中p14^ARF基因纯合性缺失、突变、CpG岛甲基化及其mRNA表达状况。结果:①胃癌组织p14^ARF基因纯合性缺失率为31.3%(15/48), 癌旁组织均未见纯合性缺失。②33例无纯合性缺失的胃癌及癌旁组织均未见p14^ARF基因点突变。③胃癌组织p14^ARF基因甲基化率为47.9%(23/48), 癌旁组织仅2例甲基化, 两者差异有显著(P＜0.01)。④45.8%(22/48)的胃癌组织p14^ARFmRNA无表达。3例外显子E1β和E2共甲基化者p14^ARFmRNA均无表达(100%), 20例单纯E2甲基化者仅3例无表达(15%), 两者差异有显著(P＜0.05)。ARF基因失活多由纯合性缺失和5’CpG岛甲基化所致, 其表达缺失与胃癌的发生密切相关。

Significance and alterations of p14ARF gene of CDKN2A locus in gastric cancer

AIM:To investigate the significance and changes of p14^ARF gene in gastric cancer.METHODS:The tumors and gastric tissues neighboring carcinoma from 48 patients with gastric cancer were studied. The homozygous deletions, mutations, methylation of the CpG islands, and mRNA expression of p14^ARF gene were assessed by PCR, PCR-SSCP, PCR based methylation assay, and RT-PCR.RESULTS:①The homozygous deletion rate of p14^ARF was 31.3% (15/48), and no homozygous deletions were examined in all the gastric tissues neighboring tumor. ②There were no point mutations of p14^ARF in 33 gastric cancers without homozygous deletion and in the matched gastric tissues adjacent to tumor. ③Methylation rate of the CpG islands of p14^ARF was significantly higher in gastric cancers(47.9%, 23/48) than that in gastric tissues neighboring cancer (4.2%, 2/48)(P＜0.01).④ No expression of p14^ARF mRNA was detected in 45.8%(22/48) of gastric cancers. Moreover, the negative rate (100%, 3/3) of p14^ARF mRNA of gastric cancers with the combined methylation of exons 1β and 2 was significantly higher than that (15%, 3/20) of the sole methylation of exon2(P＜0.05). CONCLUSION:p14^ARF gene is frequently inactivated by homozygous deletion and methylation of the 5' CpG islands in gastric cancer, which may play an important role in the development of gastric cancer.