Invasiveness of mouse embryos to human ovarian cancer cells HO8910PM and the role of MMP-9

BACKGROUND: Our previous work found that mouse embryos could invade malignant cancer cells. In the process of implantation, embryo trophoblast cells express matrix metalloproteinases and the invasive ability of trophoblast cells is proportional to matrix metalloproteinase-9 protein expression. So the purpose of this study is to observe the effects of mouse embryos on human ovarian cancer cells in the co-culture environment in vitro and explore the possible mechanism of matrix metalloproteinase-9. METHODS: Several groups of human ovarian cancer cells HO8910PM were co-cultured with mouse embryos for different time duration, after which the effects of mouse embryos on morphology and growth behavior of HO8910PM were observed under the light microscope real-time or by H.E staining. Apoptosis was detected under laser confocal microscope by Annexin V-EGFP/PI staining in situ. Invasion ability of tumor cells was studied by transwell experiments. After matrix metalloproteinase 9 (MMP −9) activity was inhibited by MMP-9 Inhibitor I, the interaction between mouse embryos and human ovarian cancer cells HO8910PM was observed. RESULTS: Mouse embryos were able to invade co-cultured human ovarian cancer cell layer which extended in the bottom of the culture dish, and gradually pushed away tumor cells to form their own growth space. The number of apoptosis tumor cells surrounding the embryo increased under laser confocal microscope. After co-cultured with mouse embryos, tumor cells invasive ability was lowered compared with the control group. After MMP-9 activity was inhibited, the interaction between mouse embryos and HO8910PM cells had no significant difference compared with the normal MMP-9 activity group. CONCLUSION: Mouse embryos were able to invade human ovarian cancer cells in vitro and form their own growth space, promote apoptosis of human ovarian cancer cells and lower their invasive ability. The mouse embryo was still able to invade human ovarian cancer cells after MMP-9 activity was inhibited.