Targeting SPP1 macrophages via the SPP1-CD44 axis reveals a key mechanism of immune suppression and tumor progression in ovarian cancer.

Tumor-associated macrophages (TAMs) play a pivotal role in immune suppression, tumor progression, and metastasis within the tumor microenvironment (TME) of ovarian cancer. While TAMs are known to promote T-cell dysfunction, the precise molecular mechanisms governing this process remain poorly understood. Here, we performed an integrated analysis of six high-grade serous ovarian cancer (HGSOC) single-cell sequencing datasets to investigate the molecular and functional diversity of TAMs in HGSOC. We identified an SPP1 TAM subpopulation enriched in HGSOC and strongly associated with poor prognosis. These macrophages promoted T-cell exhaustion via the SPP1-CD44 axis, which emerged as the principal mediator of immune suppression. Functional assays demonstrated that SPP1 secreted by TAMs drove T-cell exhaustion, weakening anti-tumor immunity. Blocking either SPP1 or CD44 effectively reversed T-cell exhaustion, restored CD8 T-cell functionality, and suppressed tumor growth in vivo. Furthermore, molecular docking and dynamics simulations identified nilotinib as a potential SPP1 inhibitor, exhibiting strong binding affinity and stability. In vitro assays confirmed that nilotinib reduced PD-1 expression in Jurkat cells induced by M2-type macrophages, underscoring its therapeutic potential in reversing T-cell exhaustion in ovarian cancer. The research demonstrates that SPP1 TAMs drive immune suppression and T-cell exhaustion in ovarian cancer via the SPP1-CD44 axis, highlighting this pathway as a promising therapeutic target for reprogramming the immune microenvironment and improving patient outcomes.