Abstract
Although tumor cell-derived microparticles (MPs) vaccines have reportedly induced antitumor immune reactions for various cancers, the mechanism by which MPs derived from Hepa1-6 cells are taken up by dendritic cells (DCs) and provide the MPs antigens message to CD8+ T cells to exert their anti-hepatocellular carcinoma (HCC) effects remain unclear. Furthermore, the role of MPs in combination with the small-molecule drug MSI-1436, an inhibitor of protein tyrosine phosphatase 1B (PTP1B), in HCC has not yet been reported. In this study, protein mass spectrometry combined with cytology revealed that MPs are mainly taken up by DCs via the clathrin-mediated endocytosis and phagocytosis pathway and localized mainly in lysosomes. High concentration of tumor necrosis factor-α and interferon-γ was detected in CD8+ T cells stimulated with MPs-loaded DCs. Moreover, MPs combined with MSI-1436 further suppressed the proliferation of HCC cells in C57BL/6 tumor-bearing mice, which was closely correlated with CD4+/CD8+ T cells counts in peripheral blood, spleen, and the tumor microenvironment. Mechanistically, the combination of MPs and MSI-1436 exerts a more powerful anti-HCC effect, which may be related to the further inhibition of the expression of PTP1B. Overall, MPs combined with MSI-1436 exerted stronger antitumor effects than MPs or MSI-1436 alone. Therefore, the combination of MPs and MSI-1436 may be a promising means of treating HCC.