Combined spatially resolved metabolomics and spatial transcriptomics reveal the mechanism of RACK1-mediated fatty acid synthesis.

Abstract

Lipid metabolism is altered in rapidly proliferating cancer cells, where fatty acids (FAs) are utilized in the synthesis of sphingolipids and glycerophospholipids to produce cell membranes and signaling molecules. Receptor for activated C-kinase 1 (RACK1; also known as small ribosomal subunit protein) is an intracellular scaffolding protein involved in signaling pathways. Whether such lipid metabolism is regulated by RACK1 is unknown. Here, integrated spatially resolved metabolomics and spatial transcriptomics revealed that accumulation of lipids in cervical cancer (CC) samples correlated with overexpression of RACK1, and RACK1 promoted lipid synthesis in CC cells. Chromatin immunoprecipitation verified binding of sterol regulatory element-binding protein 1 (SREBP1) to acetyl-CoA carboxylase (ACC) and fatty acid synthase (FASN) promoters. RACK1 enhanced de novo FA synthesis by upregulating expression of sterol regulatory element binding transcription factor 1 (SREBP1) and lipogenic genes FASN and ACC1. Co-immunoprecipitation and western blotting revealed that RACK1 interacted with protein kinase B (AKT) to activate the AKT/mammalian target of rapamycin (mTOR)/SREBP1 signaling pathway to promote FA synthesis. Cell proliferation and apoptosis experiments suggested that RACK1-regulated FA synthesis is key in the progression of CC. Thus, RACK1 enhanced lipid synthesis through the AKT/mTOR/SREBP1 signaling pathway to promote the growth of CC cells. RACK1 may become a therapeutic target for CC.