DNA甲基化调控miRNA-328的表达水平与乳腺癌预后的关系分析

目的 探讨DNA甲基化与微小RNA-328（miR-328）表达的关系及miR-328与浸润性乳腺癌临床病理特征和预后的关系。方法 回顾性分析1998年1月至2013年12月从TCGA乳腺癌芯片数据提取的1090例浸润性乳腺癌组织和104例癌旁组织的miR-328表达水平，分析从TCGA_BRCA_hMethyl450芯片数据中获取的775例浸润性乳腺癌组织和98例癌旁组织的miR-328启动子区CpG位点（cg16421621、cg04650403）甲基化率并计算启动子区甲基化与miR-328水平的相关性，从UCSC Genome Browser中的clinical_data_dictionary芯片数据中获取854例有完整临床病理资料及随访数据的乳腺癌标本，分析miR-328表达与临床病理特征及预后的关系，采用Cox回归模型分析影响预后的因素。结果 TCGA数据库1998年1月至2013年12月有miR-328表达量的1194例乳腺癌及癌旁组织中，1090例浸润性乳腺癌组织的miR-328水平为5.224±1.155，低于104例癌旁组织的6.246±0.923，差异有统计学意义（P＜0.01）；775例浸润性乳腺癌组织的miR-328基因启动子区域cg16421621和cg04650403的甲基化率分别为（0.415±0.201）%和（0.193±0.068）%，高于98例癌旁组织的（0.407±0.222）%和（0.094±0.079）%，差异有统计学意义(P＜0.01）；浸润性乳腺癌标本中miR-328的表达量与其启动子区域CG位点（cg16421621、cg04650403）甲基化率呈负相关（r=-0.127， P=0.005）。854例有完整信息的浸润性乳腺癌患者中，miR 328表达水平与淋巴结转移和肿瘤大小有关（P＜0.05）；miR-328低表达组（＜5.462）的中位总生存时间（OS）为7.25年，低于高表达组（≥5.462）的8.75年，差异有统计学意义（P<0.01）。Cox多因素回归分析显示，年龄、淋巴结转移与miR-328表达水平为影响OS的独立因素（P＜0.05），miR-328高表达组的危险程度低于低表达组（P＜0.01）。结论 浸润性乳腺癌中miR-328表达受其基因启动子区甲基化调控；miRNA-328与浸润性乳腺癌的临床病理特征有关，并能作为影响浸润性乳腺癌预后的危险因素。

Relationship of DNA methylation mediating miRNA-328 expression with clinicopathological features and prognosis of breast cancer

Objective To explore the relationship between the expression of DNA methylation and microRNA-328 (miR-328) as well as the association of miR-328 with clinicopathological features and prognosis of invasive breast cancer.Methods In a retrospective analysis,the miR-328 expression levels of 1090 cases of invasive breast cancer tissues and 104 cases of adjacent tissues from TCGA breast cancer microarray from January 1998 to December 2013 were collected.The methylation rates of miR-328 CpG promoter region (cg16421621 and cg04650403) and correlation of methylation rates of CpG sites with the level of miR-328 were analyzed from 775 cases of invasive breast cancer tissues and 98 cases of adjacent tissues obtained from TCGA_BRCA_hMethyl450 microarray data.From the clinical_data_dictionary UCSC Genome Browser chip data,854 cases with complete clinicopathological data and follow-up data of breast cancer specimens were included for the analysis of the relationship of miR-328 with clinicopathological features and prognosis.The prognostic factors affecting the prognosis were exploited using Cox multivariate analysis.Results From January 1998 to December 2013,TCGA database of 1194 cases of breast cancer and adjacent tissues with expression of miR-328 showed that the miR-328 level of 1090 cases of invasive breast cancer tissues was 5.224 ± 1.155,lower than 6.246±0.923 of 104 cases of adjacent tissues,and the difference was statistically significant (P＜0.01).The methylation rates of cg16421621 and cg04650403 in the promoter region of miR-328 were (0.415±0.201) ％ and (0.193±0.068) ％ in 775 cases of invasive breast cancer,higher than (0.407±0.222) ％ and (0.094±0.079) ％ of 98 cases of adjacent tissues (P＜0.01).The expression of miR-328 in invasive breast cancer was negatively correlated with the methylation rate of CG sites (cg16421621 and cg04650403) in the promoter region (r=-0.127,P=0.005).In 854 cases of invasive breast cancer patients with complete clinical data,the expression level of miR-328 was related to lymph node metastasis and tumor size (P＜0.05).In miR-328 low expression group,the median overall survival(OS) was 7.25 years,lower than 8.75 years of high expression group (P＜0.01).Cox multivariate analysis showed that age,lymph node metastasis and miR-328 expression were independent factors influencing OS(P＜0.05),and the risk of high expression group was lower than that of low expression group (P＜0.01).Conclusion MiR-328 expression is regulated by methylation of the promoter region of its gene in invasive breast cancer.MiR-328 is associated with clinicopathological features of invasive breast cancer,and can be used as a risk factor influencing the prognosis of invasive breast cancer.