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 a significant number of enzymatic regulators of the sphingolipid pathway have been described in detail, many remained poorly characterized. Here we applied a patient-derived systemic approach to identify and molecularly define progestin and adipoQ receptor family member IV (PAQR4) as a Golgi-localized ceramidase. PAQR4 was ~5-fold upregulated in breast cancer compared to matched control tissue and its overexpression correlated with disease-specific survival rates in breast cancer. Induction of PAQR4 in breast tumors was found to be subtype-independent and correlated with increased ceramidase activity. These findings establish PAQR4 as Golgi-localized ceramidase required for cellular growth in breast cancer.