中文摘要：

目的：应用高灵敏度的特异性茎-环反转录实时PCR技术检测分析小的非编码分子miR-342和miR-93在乳腺癌细胞中的表达。方法：用miR特异性试剂盒（miRNeasy Mini Kit）提取了总RNA和miRNA，进行特异性茎-环反转录和实时PCR（ stem-loop reverse transcription real-time PCR, stem-loop RT-qPCR），检测miR-342和miR-93在5种乳腺癌细胞中的表达，并进行比较分析。结果：用高灵敏度的特异性茎-环反转录实时PCR技术检测发现miR-93在T47D细胞系中呈非常高的表达，BT-549和MCF7细胞系中呈相对高表达，在MDA-MB-231和MDA-MB-435细胞系低表达；而miR-342在MCF7中呈非常高的表达，MDA-MB-231，BT-549和T47D中呈相对低表达，在MDA-MB-435中表达特别低。结论：miR-93和miR-342的表达在某种程度上与乳腺癌细胞高侵袭性呈一定负相关，表明miR-93和miR-342可能是乳腺癌的抑癌基因并可能具有抑制其转移的作用，为深入分析miR-93和miR-342抑制乳腺癌转移的作用机制奠定了基础。

英文摘要：

Objective： To analyze the expression of small non-coding microRNA （miRNA） molecules miR-93 and miR-342 in breast cancer cells by stem-loop reverse transcription real-time PCR technique. Methods：Total RNAs, including miRNAs, were extracted using miRNeasy Mini Kit. The expression of miR-93 and miR-342 were analyzed using stem-loop primers for reverse transcription followed by real-time PCR in five breast cancer cell lines. Results： By stem-loop RT-qPCR technique, the expression level of miR-93 was very high in breast cancer cell line T47D, relatively high in BT-549 and MCF7, but low in MDA-MB-231 and MDA-MB-435;whereas the expression level of miR-342 was very high in MCF7, low in MDA-MB-231, BT-549 and T47D, and very low in MDA-MB-435. Conclusion： Our results provide evidence that the expression levels of miR-93 and miR-342 are to a certain degree negatively correlated with high aggressiveness of cancer cells, indicating that miR-93 and miR-342, as antioncogenes, may play important roles in suppressing tumor metastasis in breast cancer. These findings might lay a foundation for further studying the mechanism of miR-93 and miR-342 in suppressing breast cancer metastasis.