Targeting Phosphatidylserine Synthesis for Tumor Cell Suppression in Esophageal Squamous Cell Carcinoma and Glioblastoma.

While altered lipid metabolism is a hallmark of cancer, specific phospholipid dependencies remain poorly defined. Here, we identify phosphatidylserine synthase 1 (PTDSS1) as a targetable metabolic vulnerability in esophageal squamous cell carcinoma (ESCC) and glioblastoma (GBM). Pharmacological inhibition of PTDSS1 selectively and potently suppresses tumor growth both in vitro and in vivo. Mechanistically, PTDSS1 blockade triggers a rapid collapse of cellular phosphatidylserine (PS) and phosphatidylethanolamine (PE) pools, fundamentally disrupting endoplasmic reticulum (ER) homeostasis. This targeted lipid depletion activates a PERK-mediated autophagic response that ultimately yields to apoptosis. Clinically, pan-cancer transcriptomic analysis links elevated PTDSS1 expression to reduced overall survival across diverse malignancies. Collectively, we establish PTDSS1 as an essential maintainer of ER integrity and highlight PS biosynthesis as a viable therapeutic target for exploiting tumor-specific metabolic dependencies.