Purpose To detect the expression profile of microRNAs ( miRNAs) in human breast cancer cells BT474 and BT474/ siR-NA HER-2, and to screen out miRNA expression profile related to HER-2. Methods RNA interference was used to inhibit HER-2 expression in human breast cancer line BT474. The expression profile of miRNAs was detected by miRNA microarray technique. Re-sults According to discrepancy power >2. 0 and P value<0. 05, there were 338 miRNAs related to HER-2, including 110 up-regu-lated and 228 down-regulated miRNAs. Conclusion miRNA microarrays can detect the differentially expressed miRNAs in human breast cancer BT474 cells with different level of HER-2. The miRNAs related to HER-2 which play a role in breast cancer should be found after further analysis.

Purpose To screen out miRNA expression profile related to HER-2 via observing the differential expression of miRNA ex-pression of human breast cancer cells MCF-7 and MCF-7/HER-2. Methods After cultivating human breast cancer cells MCF-7 and MCF-7/HER-2, the expression profile of miRNAs was detected by miRNA microarrays. Results Compared to MCF-7 cells, two hundreds and seventeen HER-2 related miRNAs were identified from breast cancer MCF-7/HER-2 cells, including 123 up-regulated and 94 down-regulated miRNAs. Of significant differentialy expressed miRNAs, hsa-miR-141 and hsa-miR-1299’s target genes have multiple biological functions. Conclusion The differentially expressed miRNAs under different lever of HER-2 in human breast cancer MCF-7 cells were obtained, which may provide a basis for studying HER-2 functions and roles in breast cancer.