Objective:To explore changes of microRNA expression profiling in human breast cancer cell based on prolactin(PRL) treatment,and to understand their potential roles in breast cancer initiation and progression. Methods:Human breast cancer T-47D cells,in which PRL receptor(PRLR) is highly expressed,were treated with or without human recombinant PRL,two group cells were subjected to detect their proliferation,cell cycle and apoptosis alteration by the MTT assay and flow cytometry method (FCM). miRNA expression profile of PRL treated and untreated cells were analyzed by Solexa sequencing technology,miRNAs were validated by real-time PCR and undertaken bioinformatic analysis. Results:In MTT results,it showed that T-47D cell proliferation ability was enhanced by PRL treatment. FCM revealed that G1 phase cells were reduced,while S phase cells were increased. Meanwhile,cell apoptotic rate was reduced in PRL group. Two miRNAs expression profiles were successfully analyzed from PRL-treated and untreated T-47D cells by Solexa sequencing technology. Within the Solexa sequencing results,821 and 798 miRNAs were detected in the two libraries,respectively. 428 miRNAs were co-expressed,and 42 miRNAs were significantly differentially expressed. Four miRNAs were validated by real-time PCR,their intracellular expression was consistent with Solexa sequencing data. Besides,86 and 115 novel miRNAs were also detected in the two libraries,and 46 novel miRNAs were co-expressed. Conclusion:PRL can enhance breast cancer cell proliferation ability,and miRNAs expression profiles in T-47D cells treated with or without PRL are successfully analyzed by Solexa sequencing technology. Series of PRLR signaling pathway related miRNAs were harvested. This study provides a reference for elucidating the complex miRNA-mediated regulatory networks of PRL/PRLR signaling pathway that affect breast cancer tumorigenesis and progression.