mdm2/p53通路相关的乳腺癌差异表达基因分析

Analyses on the differentially expressed genes associated with murine double minute 2/p53 pathway in breast cancer

目的比较乳腺癌和正常乳腺组织的基因表达差异,探讨与mdm2/p53通路相关的差异表达基因。方法提取11例乳腺癌和将5例正常乳腺组织等比例混合的组织总RNA进行芯片杂交,用SAM软件筛选差异表达基因,用GoMiner软件检索差异表达基因的功能,挑选参与细胞周期和凋亡的基因,通过Pathway分析方法检索与mdm2/p53通路相关的差异基因;用免疫组化方法验证差异基因cyclin A2及其相关基因CDK2在乳腺癌(38例)和正常乳腺组织(16例)中的表达。结果乳腺癌与正常乳腺组织的差异表达基因共548个,其中参与细胞周期的基因有35个,参与凋亡的基因有23个;与mdm2/p53通路相关的差异基因有4个,分别是cyclin A2,cyclin B1,PCNA,YWHAZ;经免疫组化验证的38例乳腺癌和16例正常乳腺组织的cyclin A2表达阳性率分别为42.1%(16/38,和6.25% (1/16);CDK2表达阳性率分别为47.3%(18/38)和6.25%(1/16),两者均有统计学差异(P<0.05);在乳腺癌中cyclin A2与CDK2的表达呈正相关,特别值得一提的是如果以≥2^+为阳性在乳腺癌cyclin A2为26.3%,CDK2为31.5%,而在正常组几乎看不到≥2^+的表达。结论乳腺癌组织与正常乳腺组织相比存在着差异表达基因,与mdm2/p53通路相关的差异基因的异常高表达促进细胞增殖,与乳腺癌的发生密切相关,而cyclin A2和CDK2在乳腺癌共表达并明显高于正常组织其意义还不清楚。

Objective To find a set of differentially expressed genes associated with mdm2/p53 pathway by comparing the difference of gene expression in breast cancer and normal breast tissues. Methods Total RNAs were extracted respectively from 11 breast cancer tissues and the corresponding mixed tissues of 5 normal breast tissues and were used as training cases through Oligo microarray hybridization. Differentially expressed genes were screened using the software Significance Analysis of Microarray （SAM）. The functions of the differentially expressed genes was searched using GoMiner and genes which participated in cell cycle and apoptosis were screened. Differentially expressed genes correlating with mdm2/p53 pathway were searched by Pathway analyse. The expressions of differentially expressed genes, cyclin A2 and CDK2, were further confirmed by immunohistochemistry （IHC） method in breast cancer （38 cases） and normal breast tissue （ 16 cases）. Results Totally 548 differentially expressed genes were selected, of which 35 genes participated in cell cycle, 23 genes in apoptosis, and 4 genes （cyclin A2, cyclin B1, PCNA, and YWHAZ） correlating with mdm2/p53 pathway. IHC showed that both cyclin A2 and CDK2 were significantly different between breast cancer and normal tissue （ P 〈 0. 05 ） ： in breast cancer and normal tissue the positive rates of cyclin A2 were 42. 1% （16/38） and 6.25% （1/16） and CDK2 were 47.3% （18/38） and 6.25% （1/16）, respectively （both P 〈 0. 05）. About 50% of breast cancer cyclin A2 were co -expressed with CDK2. Conclusion The differentially expressed genes exist in breast cancer. Abnormal high expressions of differentially expressed genes associated with mdm2/p53 pathway may accelerate cell proliferation and cause the occurrence and evolution of breast cancer.