Targeting de novo cholesterol synthesis in rhabdomyosarcoma induces cell cycle arrest and triggers apoptosis through ER stress-mediated pathways

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children, but the outcomes of high-grade RMS patients remain poor, underscoring the critical need for novel therapeutic strategies. Although metabolic pathways in RMS are incompletely characterized, emerging evidence suggests that metabolic adaptations in RMS resemble those in other malignancies. Here, we identify elevated cholesterol biosynthesis driven by the PROX1 transcription factor as a defining feature of RMS. Our findings demonstrate that the cholesterol biosynthesis pathway is essential for RMS cell growth, proliferation, and survival. Blocking this pathway through genetic or pharmacological inhibition of the key cholesterol biosynthesis enzymes significantly impairs RMS cell proliferation, halts cell cycle progression, and triggers apoptosis through activation of endoplasmic reticulum stress pathways. We furthermore validate the critical role of cholesterol biosynthesis in RMS progression in tumor xenograft models, demonstrating that silencing of the DHCR7 gene significantly suppresses tumor growth. Transcriptomic analysis revealed widespread downregulation of cell cycle-related genes following DHCR7 silencing, further supporting the role of cholesterol metabolism in cell cycle regulation. These results highlight the vulnerability of RMS cells to cholesterol biosynthesis inhibition and suggest that targeting this metabolic pathway as a promising therapeutic approach for improving RMS outcomes. Our findings provide a rationale for the development of novel therapies targeted to cholesterol biosynthesis in this aggressive cancer. SignificanceThis study reveals that targeting cholesterol biosynthesis in rhabdomyosarcoma induces ER-stress, apoptosis and cell cycle arrest, highlighting a potential therapeutic strategy for treating this aggressive pediatric cancer.