Syntaxin 12 Sustains Endosomal‐Lysosomal Homeostasis and Survival in Glioblastoma Stem‐Like Cells

Glioblastoma cells display a striking vulnerability to disruptions in late endosome-lysosome trafficking, a dependency that we exploited through a targeted siRNA screen in patient-derived cells with stem-like properties (GSCs). This screen identified Syntaxin 12 (STX12) as a critical determinant of GSC survival. Originally characterized as a recycling endosome t-SNARE, STX12 regulates tubular recycling and retrograde transport, yet its broader implications for lysosomal homeostasis remain poorly understood. Functional characterization revealed that STX12 is required to maintain lysosomal organization in GSCs, consistent with its known roles as an endosomal t-SNARE. Loss of STX12 altered dynamic processes that support GSC fitness, culminating in controlling life-and-death decisions. Because lysosomal function is deeply connected with the autophagic pathway, we next explored whether STX12 contributes to this adaptive program. STX12 silencing produced signatures consistent with impaired endo-lysosomal progression and disrupted mechanistic target of rapamycin (mTOR)/lysosome communication. This work further identifies a previously unrecognized role for STX12 in the adaptive trafficking network that supports glioblastoma cell survival, revealing a potential SNARE-centered vulnerability for therapeutic intervention.