Golgi-localized PAQR4 mediates Anti-apoptotic Ceramidase Activity in Breast Cancer

The metabolic network of sphingolipids plays important roles in cancer biology. Prominent sphingolipids include ceramides and sphingosine-1-phosphate that regulate multiple aspects of growth, apoptosis and cellular signaling. Although many significant enzymatic regulators of the sphingolipid pathway have been described in detail, the list is currently incomplete. Here, we applied a systemic approach to identify and molecularly define progestin and adipoQ receptor family member IV (PAQR4) as a Golgi-localized ceramidase. We find PAQR4 to be [~]5 fold upregulated in breast cancer compared to matched control tissue and that its overexpression correlate with disease-specific survival rates in breast cancer. PAQR4 is a seven transmembrane protein, and depletion of PAQR4 leads to cellular apoptosis through accumulation of ceramides. Our findings establish PAQR4 as Golgi-localized ceramidase required for cellular growth in breast cancer.