VDR-Mediated Inhibition of Glycolysis and Metastasis by Calcitriol in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with high metastatic potential and limited therapeutic options. This study investigates the effects of calcitriol, an active metabolite of vitamin D, on TNBC progression by targeting the vitamin D receptor (VDR)-mediated hypoxia-inducible factor-1α (HIF-1α) axis. We established in vivo TNBC xenograft models using 4T1 cells and in vitro models with MDA-MB-231 and 4T1 cells overexpressing HIF-1α. Results showed that calcitriol inhibited lung metastasis and downregulated glycolytic activity in TNBC xenografts without affecting primary tumor growth. In vitro, calcitriol reduced cell viability, migration, and invasion by suppressing HIF-1α expression. It also decreased glucose uptake, lactate production, and ATP levels while downregulating key glycolytic regulators. VDR knockdown abolished these effects, confirming VDR as the critical mediator. Our findings suggest that calcitriol exerts anti-metastatic effects in TNBC by modulating the VDR-HIF-1α axis, inhibiting glycolysis, and suppressing the epithelial-mesenchymal transition. This study highlights the potential therapeutic role of calcitriol in TNBC treatment by targeting both metabolic reprogramming and invasive capacity. Future research should further explore the mechanisms underlying calcitriol-mediated HIF-1α suppression and its clinical application in TNBC.