AbstractThe tumor microenvironment (TME) modulates therapeutic response and prognosis in patients with bladder cancer (BC). The roles of two phospholipase D (PLD) isoforms, PLD1 and PLD2 (hydrolysis of phosphatidylcholine to phosphatidic acid), in cancer cells have been well‐studied in numerous cancer types, but their roles in the TME remain unclear. We used a mouse BC Pld2‐KO carcinogenesis model and global transcriptomic analysis to reveal that PLD2 was significantly involved in BC progression through immunosuppressive pathways in the TME. We therefore focused on PLD2 and tumor‐associated macrophages (TAMs), which were increased in Pld2‐KO mice and further associated with poor prognoses in BC patients. In vitro, we found that Pld2‐KO mouse TAMs had significantly enhanced proliferation, correlating closely with increased interleukin‐1β (IL‐1β) production. These results indicate that PLD2 suppresses BC progression by regulation of IL‐1β secretion from TAMs in the TME, suggesting that PLD2 could serve as a potential therapeutic target for modifying the TME in BC.
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