Targeting VPS4 elicits STING-driven anti-tumor immunity to suppress rhabdomyosarcoma growth.

The AAA+ ATPase VPS4 drives the ESCRT machinery in diverse intracellular membrane remodeling events, including endocytic receptor sorting, membrane repair, and autophagosome closure. Tumor cells often lose one VPS4 paralog (VPS4A or VPS4B), making them dependent on the remaining enzyme and creating a potential therapeutic vulnerability. Inhibiting VPS4 induces cancer cell-autonomous death and may also modulate the immune microenvironment, although the underlying mechanisms remain unclear. Here, we report that VPS4 inhibition triggered upregulation of cytokine and innate immune signaling, along with canonical NF-κB, stress response, and cell death pathways in murine rhabdomyosarcoma (RMS) cells. Pharmacological and genetic analyses identified the cGAS-STING-TBK1-IRF3 axis, activated by cytoplasmic mitochondrial DNA, as the primary driver of cytokine induction. In an orthotopic syngeneic RMS model, VPS4 inhibition suppressed tumor growth while fostering a more immunogenic microenvironment. Although STING was dispensable for VPS4 inhibition-induced RMS cell death, its loss reduced natural killer and dendritic cell infiltration and attenuated the overall anti-tumor effects of VPS4 inhibition. These findings establish a dual role for VPS4 inhibition in inducing tumor cell death and promoting anti-tumor immunity, highlighting the therapeutic potential of targeting VPS4 vulnerability in cancer.