Hypoxia activates SREBP2 through Golgi disassembly in bone marrow‐derived monocytes for enhanced tumor growth.

Bone marrow‐derived cells (BMDCs) infiltrate hypoxic tumors at a pre‐angiogenic state and differentiate into mature macrophages, thereby inducing pro‐tumorigenic immunity. A critical factor regulating this differentiation is activation of SREBP2—a well‐known transcription factor participating in tumorigenesis progression—through unknown cellular mechanisms. Here, we show that hypoxia‐induced Golgi disassembly and Golgi‐ER fusion in monocytic myeloid cells result in nuclear translocation and activation of SREBP2 in a SCAP‐independent manner. Notably, hypoxia‐induced SREBP2 activation was only observed in an immature lineage of bone marrow‐derived cells. Single‐cell RNA‐seq analysis revealed that SREBP2‐mediated cholesterol biosynthesis was upregulated in HSCs and monocytes but not in macrophages in the hypoxic bone marrow niche. Moreover, inhibition of cholesterol biosynthesis impaired tumor growth through suppression of pro‐tumorigenic immunity and angiogenesis. Thus, our findings indicate that Golgi‐ER fusion regulates SREBP2‐mediated metabolic alteration in lineage‐specific BMDCs under hypoxia for tumor progression. Synopsis: Bone marrow‐derived cells (BMDCs) infiltrate hypoxic tumors enhancing malignant angiogenesis and immunity, but how low‐oxygen conditions alter BMDC activity remains unclear. This study reports hypoxia‐induced Golgi disassembly and cholesterol biosynthesis as a novel organelle‐mediated regulation of monocytic BMDCs for enhanced tumorigenesis. Hypoxia triggers cholesterol biosynthesis in BMDCs and cancer cell line‐induced tumors in mice.Hypoxia‐induced cholesterol biosynthesis requires Golgi disassembly‐mediated activation of SREBP2 in monocytic myeloid cells.Hypoxia‐induced SREBP2 activation is lineage‐specific and reduced during monocyte differentiation.Inhibition of cholesterol biosynthesis suppresses tumor growth through reduced infiltration of pro‐tumorigenic BMDCs. [ABSTRACT FROM AUTHOR]