SENP1 regulates the malignant activities of osteosarcoma cells and antitumor immunity via the cGAS-STING signaling.

Osteosarcoma is an aggressive bone malignancy with poor prognosis. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway is critical in anti-tumor immunity, its regulation in osteosarcoma remains unclear. Through UALCAN database screening, we identified elevated SUMO-specific protease 1 (SENP1) expression in sarcoma tissues, but whether it affects STING pathway remains unclear. Although other SENP family members (such as SENP2 and SENP6) have been implicated in immune regulation, their direct role in STING deSUMOylation within the osteosarcoma is limited. Herein, we explore how SENP1 (SUMO-specific protease 1) influences osteosarcoma progression and anti-tumor immunity by modulating the cGAS-STING pathway. SENP1 expression was preliminary analyzed by Gene Expression Profiling Interactive Analysis (GEPIA) webserver and The Cancer Genome Atlas (TCGA) dataset, and further verified by western blot. Cell malignant activities were determined by functional assays Specific protein expressions were analyzed by western blot and immunohistochemistry. The mechanism of SENP1 regulating cGAS-STING pathway was validated by immunoprecipitation (IP) and co-immunoprecipitation (Co-IP) assays. In vivo experiments were finally conducted to verify the function of SENP1. The expression of SENP1 was markedly elevated in osteosarcoma cell lines. SENP1 silencing markedly suppressed the proliferation, migration, and invasion of U2OS and MG63 cells. Additionally, SENP1 silencing upregulated cGAS and STING protein levels. Mechanistically, SENP1 interacted with cGAS and regulated its SUMOylation status. The inhibitory effects of SENP1 knockdown on osteosarcoma cell proliferation, migration, and invasion, as well as its promotive effects on CD8+ T cell migration and the secretion of cytotoxic factors (IFN-γ, GZMB, and IL-2), were significantly reversed by concomitant cGAS depletion. In vivo, SENP1 deficiency inhibited tumor growth in xenograft models, activated the cGAS-STING pathway, and enhanced CD8+ T cell-mediated cytotoxicity. SENP1 silencing restrains osteosarcoma cell proliferation, migration, invasion and facilitates anti-tumor immunity via activation of the cGAS-STING signaling.