The lysosomal TRPML1 channel promotes breast cancer survival by supporting mitochondrial function and cellular metabolism

Triple-negative breast cancer (TNBC) is an aggressive subtype representing approximately 10%-20% of breast cancers and lacking effective therapies. TRPML1, which is a lysosomal Ca2+ release channel upregulated in TNBC, promotes TNBC tumor growth. Here we show a novel crosstalk between lysosomes and mitochondria mediated by TRPML1 in TNBC. TRPML1 is required for the maintenance of mitochondrial function and reactive oxygen species (ROS) homeostasis. TRPML1 knockdown inhibits TNBC mitochondrial respiration, glycolysis and ATP production, leading to reduced proliferation, promotion of cell cycle arrest and apoptosis with enhanced global and mitochondrial ROS. Further, TRPML1 downregulation enhances the cytotoxic effect of Doxorubicin in TNBC cells. Our data reveal a hitherto unknown link between lysosomal TRPML1 channels and mitochondrial metabolism and suggest that TRPML1 inhibition in combination with established chemotherapies could be an effective strategy against TNBC tumors.