The impact of IDO2 expression in B16-BL6 cells on melanoma formation and growth

LIU Yanling; XU Ping; XU Na; CHEN Xiaoyan; FANG Chunjuan; MIN Weiping

doi:10.13431/j.cnki.immunol.j.20180029

Abstract：This study was performed to investigate the impact of IDO2 in B16-B6 cells on melanoma progression and anti-tumor immunity in mouse model.B16-BL6 cells were transfected with IDO2-shRNA or scramble-shRNA to establish stable cell lines of B16-BL6/IDO2-and B16-BL6/IDO2+ by G418 screening.Then qPCR and MTF were used to detect IDO2 expression and the impact of IDO2 expression on cell proliferation,respectively.Simultaneously,the stable cell line of B16-BL6/IDO2+ or B16-BL6/IDO2-was injected into mouse to identify the impact of IDO2 expression on the melanoma formation and growth.At the endpoint of experiments,flow cytometry was used to detect the percentage of Treg ceils,populations of CD8+/CD4+ T cells and T cells apoptosis in draining lymph nodes.LDH assay was used to determine the cytotoxic T lymphocytes (CTL) activity.Data showed that the B16-BL6/IDO2+ and B16-BL6/IDO2-stable cell lines were established successfully.IDO2 expression in B16-BL6/IDO2-cell line was stable,lower and continuous,which could not be induced by LPS and IFN-γ.Comparing B16-BL6/IDO2 + stable cell line,the proliferation of B16-BL6/IDO2-was inhibited in vitro,and inoculation of B16-BL6/IDO2-stable cell line into the mouse can decreased the tumor growth rate and reduced the tumor weight in vivo.Flow cytometry results showed that in tumor draining LNs,the percentage of Treg and the apoptosis of T cell was decreased,while CD8+T cell subset was increased and CD8+T cell cytotoxic activity was enhanced.In conclusion,the expression of IDO2 in B16-BL6 melanoma cells plays a promoting role in the growth of tumor,and can affect the immune response in the tumor draining lymph node.