T cells play important roles in antitumor immunity. However, given that the hepatocellular carcinoma (HCC) tumor microenvironment confers resistance to T cell-based immunotherapies, novel strategies to boost T cell-mediated antitumor efficacy are urgently needed for the treatment of HCC. Here, we show that high proprotein convertase subtilisin/kexin type9 (PCSK9) expression was negatively associated with HCC patient's overall survival and markers of CD8+ T cells. Pharmacological inhibition of PCSK9 enhanced tumor-specific killing and downregulated PD-1 expression of AFP-specific TCR-T. Inhibition of PCSK9 significantly enhances the anti-HCC efficacy of TCR-T cells and anti-PD-1 immunotherapy in vivo. Moreover, PCSK9 inhibitor suppressed HCC growth dependent on CD8+ T cells. Mechanically, pharmacological inhibition of PCSK9 promoted low-density lipoprotein receptor (LDLR)-mediated activation of mTORC1 signaling in CD8+ T cells. LDLR deficiency was shown to impair cellular mTORC1 signaling and the anti-HCC function of CD8 T cells. On the basis of our findings in this study, we propose a potential metabolic intervention strategy that could be used to enhance the antitumor effects of immunotherapy for HCC.
Keywords: TCR-engineered T cell (TCR-T); hepatocellular carcinoma (HCC); low-density lipoprotein receptor (LDLR); proprotein convertase subtilisin/kexin 9 (PCSK9).
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