Abstract:

　　［Abstract］ Background and purpose: Studies have shown that ribosomal protein L8 (RPL8) is shared by melanomas, gliomas and ovarian carcinomas. A peptide of RPL8 significantly stimulated proliferation and cytokine expression of the hepler T cell clone and lymphocytes in melanoma patients. RPL8 may stimulate anti-tumor immunity, making RPL8 an attractive candidate for therapeutic intervention. In this study, we prepared DC pulsed by RPL8 (RPL8-DC) and investigate the anti-tumor effect of RPL8-DC on melanoma in mice. Methods: The recombinant protein was achieved through IPTG induction in E. coli and identified with Western blot. Bone marrow-derived DC was loaded with RPL8 protein. RPL8 and CD11c, CD80, MHC-Ⅰ, MHC-Ⅱ molecules on dentritic cells were monitored by fluorescence microscope and FACS analysis, respectively. The anti-tumor effect of T cells in vitro was detected by MTT assay. Subcutaneous tumors were induced in C57BL/6 mice using B16 cells. The tumor volumes were measured after injection with RPL8-DC. Results: The purified protein was combined with specific antibodies. DCs pulsed by RPL8 were visualized under fluorescent microscopy. CD11c, CD80, MHC-Ⅰ, MHC-Ⅱ molecules on DCs were up-regulated after stimulation with RPL8 and LPS. B16 cells were inhibited by T cells stimulated with RPL8-DC. The inhibition rate of tumor cells was 70% in RPL8-DC group when effector-to-target ratio was 30∶1, which was higher than PBS and DC groups. Inhibition of growth could be observed more significantly in mice after the treatment with RPL8-DC. The mice receiving the therapy of RPL8-DC were able to survive much longer than the mice receiving control therapy. Conclusion: The DC pulsed by RPL8 protein can inhibit the growth of melanoma.

Key words: Ribosomal protein L8, Dendritic cells, Melanoma, Immunotherapy