NK4 Inhibits Tumor Growth Of Human Ovarian Cancer Xenograft In Nude Mice By NK Cells

Background and objective: Hepatocyte growth factor(HGF)has its function after binding its receptor c-Met.NK4 is a four-kringle antagonist of HGF and exerts an antitumor activity,not only by HGF antagonism but also by antiangiogenesis.In order to clarify the antitumor activity of NK4 in ovarian cancer and investigate NK4 as a potential therapeutic method to ovarian cancer,NK4 cDNA was induced into a human ovarian cancer cell line SKOV-3.Then the effect of transfected NK4 gene on tumor growth in nude mice of human ovarian cancer xenograft and whether NK4 inhibited the development of human ovarian cancer through NK cells in nude mice were researched.Methods: SKOV-3 cells were transfected with NK4 or luciferase expression plasmids.After antibiotics selected,NK4-expressing cells(SKOV-3/NK4)and control cells(SKOV-3/LUC)were obtained.Western blot analysis was used to detect NK4 expression in thesupernatant fluid of SKOV-3,SKOV-3/LUC and SKOV-3/NK4 cells.Western blot analysis was used to detect c-Met and phospho-c-Met expression in the cell lysis of SKOV-3 cells cultured with supernatants from SKOV-3,SKOV-3/LUC and SKOV-3/NK4 cells.Subcutaneous tumor growth curve were performed according to the xenograft tumor volume among the three groups(SKOV-3,SKOV-3/LUC and SKOV-3/NK4).After the paraffin sections,implant tumor tissues were labeled with CD49 b antibody,the number of NK cells in the SKOV-3 /NK4 group and the SKOV-3 /LUC group were counted and compared between the two groups..Results: NK4 was detected in the supernatant of SKOV-3/NK4 and NK4 expressed in the supernatant of SKOV-3/NK4 inhibited phosphorylation of c-Met in SKOV-3 cells.The subcutaneous tumor volume in SKOV-3/NK4 group was significantly smaller than that in the control(SKOV-3 or SKOV-3/LUC)groups(P<0.05).The number of NK cells in the SKOV-3 /NK4 group and SKOV-3/LUC group were counted after the paraffin sections of implant tumor tissues and labeled with CD49 b antibody.The number of NK cells in the SKOV-3 /NK4 group was significantly higher than that in the SKOV-3 /LUC group(P<0.05).Conclusions:NK4 can be expressed by established SKOV-3/NK4 cells and NK4 caninhibit phosphorylation of c-Met in SKOV-3 cells.NK4 promotes NK cell aggregation in tumor tissues and inhibit ovarian cancer growth in nude mice.These findings suggest NK4 can be a novel gene targeted therapeutic strategy to human ovarian cancer.