Xia Lin, Zhang Dexin, Du Rui, Pan Yanglin, Zhao Lina, Sun Shiren, Hong Liu, Liu Jie, Fan Daiming
State Key Laboratory of Cancer Biology and Institute of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China.
Int J Cancer. 2008 Jul 15;123(2):372-379. doi: 10.1002/ijc.23501.
microRNAs are endogenous small noncoding RNAs that regulate gene expression negatively at posttranscriptional level. This latest addition to the complex gene regulatory circuitry revolutionizes our way to understanding physiological and pathological processes in the human body. Here we investigated the possible role of microRNAs in the development of multidrug resistance (MDR) in gastric cancer cells. microRNA expression profiling revealed a limited set of microRNAs with altered expression in multidrug- resistant gastric cancer cell line SGC7901/VCR compared to its parental SGC7901 cell line. Among the downregulated microRNAs are miR-15b and miR-16, members of miR-15/16 family, whose expression was further validated by qRT-PCR. In vitro drug sensitivity assay demonstrated that overexpression of miR-15b or miR-16 sensitized SGC7901/VCR cells to anticancer drugs whereas inhibition of them using antisense oligonucleotides conferred SGC7901 cells MDR. The downregulation of miR-15b and miR-16 in SGC7901/VCR cells was concurrent with the upregulation of Bcl-2 protein. Enforced mir-15b or miR-16 expression reduced Bcl-2 protein level and the luciferase activity of a BCL2 3' untranslated region-based reporter construct in SGC7901/VCR cells, suggesting that BCL2 is a direct target of miR-15b and miR-16. Moreover, overexpression of miR-15b or miR-16 could sensitize SGC7901/VCR cells to VCR-induced apoptosis. Taken together, our findings suggest that miR-15b and miR-16 could play a role in the development of MDR in gastric cancer cells at least in part by modulation of apoptosis via targeting BCL2.
微小RNA是内源性小非编码RNA，在转录后水平负向调节基因表达。这一复杂基因调控网络中的最新成员彻底改变了我们理解人体生理和病理过程的方式。在此，我们研究了微小RNA在胃癌细胞多药耐药（MDR）发展中的可能作用。微小RNA表达谱分析显示，与亲本SGC7901细胞系相比，多药耐药胃癌细胞系SGC7901/VCR中表达改变的微小RNA数量有限。下调的微小RNA中包括miR-15b和miR-16，它们是miR-15/16家族的成员，其表达通过qRT-PCR进一步验证。体外药物敏感性试验表明，miR-15b或miR-16的过表达使SGC7901/VCR细胞对抗癌药物敏感，而使用反义寡核苷酸抑制它们则赋予SGC7901细胞多药耐药性。SGC7901/VCR细胞中miR-15b和miR-16的下调与Bcl-2蛋白的上调同时发生。在SGC7901/VCR细胞中，强制表达mir-15b或miR-16可降低Bcl-2蛋白水平以及基于BCL2 3'非翻译区的报告基因构建体的荧光素酶活性，这表明BCL2是miR-15b和miR-16的直接靶标。此外，miR-15b或miR-16的过表达可使SGC7901/VCR细胞对长春新碱诱导的凋亡敏感。综上所述，我们的研究结果表明，miR-15b和miR-16至少部分通过靶向BCL2调节凋亡，从而在胃癌细胞多药耐药的发展中发挥作用。
