Objective       To determine the effect of interferon-β (IFN-β)/ enhanced green fluorescent protein (EGFP)-expressing mesenchymal stem cells (IFN-β-hMSCs) on the proliferation of prostate cancer cell line PC-3.       Methods      The secreted eukaryotic expressed vector for recombinant secreted protein IFN-β/EGFP was constructed and then transfected into hMSCs by lipofectamine. EGFP was detected by inverted fluorescence microscopy. The expression of IFN-β in the medium of hMSCs-IFN-β was detected by ELISA. IFN-β-hMSCs were incubated with prostate cancer cell line PC-3 in Transwell co-culture system. hMSCs

mock-hMSCs and PC-3 served as control cells. PC-3 cells were trypsinized and viable cells were counted respectively in 1

3

and 5 d using a hemocytometer after trypan blue staining.       Results       Fluorescence microscopy showed that the cells had positive fluorescent signals

and IFN-β was detected in the culture medium of IFN-β-hMSCs. IFN-β-hMSCs resulted in a significant decrease in PC-3 cells survival as compared with control groups (P0.05).       Conclusion      hMSCs expresses secreted protein IFN-β/EGFP successfully after gene transfection

and IFN-β-hMSCs cells inhibit growth significantly in the prostate cancer cells. IFN-β and EGFP keep their individual characteristics with no interference with each other.