Synergistic immunotherapeutic effects of Lycium barbarum polysaccharide and interferon-alpha 2b on the murine Renca renal cell carcinoma cell line in vitro and in vivo

摘要

Novel therapeutic strategies to improve clinical efficacy in patients with renal cell carcinoma (RCC) are required. The possibility of combination therapy with Lycium barbarum polysaccharides (LBP) and recombinant interferon (IFN)-alpha 2b remains to be elucidated in RCC. The present study investigated the putative synergistic immunotherapeutic roles of LBP and IFN-alpha 2b against RCC in vitro and in vivo. The mouse RCC cell line, Renca, was used for in vitro experiments. Treatment of the cells with a combination of LBP and IFN-alpha 2b markedly inhibited cell proliferation, retarded cell cycle growth and promoted apoptosis in the Renca cells. Western blot analysis revealed that LBP and IFN-alpha 2b synergistically downregulated the expression levels of cyclin D1, c-Myc and Bcl-2, and upregulated the expression of the antiapoptotic protein, Bax. Myeloid-derived suppressor cells (MDSCs) were markedly upregulated during tumour progression and promoted tumour growth by inhibiting the T-cell-mediated immune response. In vivo, a marked reduction in the MDSC ratio and tumour volume was observed in a group receiving combined treatment with LBP and IFN-alpha 2b in a xenograft tumour model. In conclusion, the present study suggested that the combination of LBP and IFN-alpha 2b is likely to be more effective in treating murine RCC compared with the less pronounced immunotherapeutic effects of administering LBP or IFN-alpha 2b alone.