Abstract
Pancreatic ductal adenocarcinoma (PDAC) is not sensitive to immune checkpoint blockade therapy, and negative feedback of tumor immune evasion might be partly responsible. We isolated CD8+ T cells and cultured them in vitro. Proteomics analysis was performed to compare changes in Panc02 cell lines cultured with conditioned medium, and leucine-rich repeat kinase 2 (LRRK2) was identified as a differential gene. LRRK2 expression was related to CD8+ T cell spatial distribution in PDAC clinical samples and upregulated by CD8+ T cells via interferon gamma (IFN-γ) simulation in vitro. Knockdown or pharmacological inhibition of LRRK2 activated an anti-pancreatic cancer immune response in mice, which meant that LRRK2 acted as an immunosuppressive gene. Mechanistically, LRRK2 phosphorylated PD-L1 at T210 to inhibit its ubiquitination-mediated proteasomal degradation. LRRK2 inhibition attenuated PD-1/PD-L1 blockade-mediated, T cell-induced upregulation of LRRK2/PD-L1, thus sensitizing the mice to anti-PD-L1 therapy. In addition, adenosylcobalamin, the activated form of vitamin B12, which was found to be a broad-spectrum inhibitor of LRRK2, could inhibit LRRK2 in vivo and sensitize PDAC to immunotherapy as well, which potentially endows LRRK2 inhibition with clinical translational value. Therefore, PD-L1 blockade combined with LRRK2 inhibition could be a novel therapy strategy for PDAC.