Study on apoptosis-inducing effect for mouse mammary cancer cells transfected with IL-23 gene in vitro and in vivo

Objective:To investigate the changes in apoptosis of mouse mammary cancer cells (MA-891) after transfection with IL-23 gene in vitro and in vivo and explore the anti-tumor mechanism of IL-23. Methods: IL-23 gene was transferred into two packing cell lines (ectotrophic ψ2 and amphotrophic PA317) in sequence by a retrovirus vector (LXSN), and the positive cellular clones that can produce retroviruses carrying IL-23 gene were screened by G418. The retroviruses were used to transduce the mIL-23 gene into mouse mammary cancer cells (MA-891). After being screened by G418, IL-23/MA-891 cells expressing IL-23 protein were obtained. The expression of IL-23 protein in IL-23/MA-891 cells was detected by ELISA method. The proliferations of MA-891, LXSN/MA-891 and IL-23/MA-891 cells were detected by MTT assay in vitro. Mice were subcutaneously inoculated with IL-23/MA-891, LXSN/MA-891 and the parental MA-891 cells and the solid tumor formation was observed in vivo. The apoptosis of tumor cells from mice injected with different MA-891 cells was detected by TUNEL and flow cytometry analysis. The expressions of Fas and survivin were determined by RT-PCR and Western blotting in vivo. Results: IL-23 gene was successfully transfected into MA-891 cells. The stable IL-23/MA-891 cells with over-expression of IL-23 was obtained. Transfection with IL-23 gene had significant effects on the proliferation and apoptosis of MA-891 cells in vitro (P0.05). But the tumor growth in mice was greatly inhibited and apoptosis ratio of tumor tissues was significantly increased in the IL-23 gene-transfected group compared with the control group (P0.01). The expression of Fas on the surface of cells was up-regulated and the expression of survivin was significantly decreased (P0.01). Conclusion: Transfection with IL-23 gene has no significant effects on the apoptosis of MA-891 cells in vitro. But IL-23 exerts its anti-tumor effect by up-regulating the expression of Fas and down-regulating the expression of survivin in vivo.