title: Acid Ceramidase in Melanoma: EXPRESSION, LOCALIZATION, AND EFFECTS OF PHARMACOLOGICAL INHIBITION.
abstract: Acid ceramidase (AC) is a lysosomal cysteine amidase that controls sphingolipid signaling by lowering the levels of ceramides and concomitantly increasing those of sphingosine and its bioactive metabolite, sphingosine 1-phosphate. In the present study, we evaluated the role of AC-regulated sphingolipid signaling in melanoma. We found that AC expression is markedly elevated in normal human melanocytes and proliferative melanoma cell lines, compared with other skin cells (keratinocytes and fibroblasts) and non-melanoma cancer cells. High AC expression was also observed in biopsies from human subjects with Stage II melanoma. Immunofluorescence studies revealed that the subcellular localization of AC differs between melanocytes (where it is found in both cytosol and nucleus) and melanoma cells (where it is primarily localized to cytosol). In addition to having high AC levels, melanoma cells generate lower amounts of ceramides than normal melanocytes do. This down-regulation in ceramide production appears to result from suppression of the de novo biosynthesis pathway. To test whether AC might contribute to melanoma cell proliferation, we blocked AC activity using a new potent (IC50 = 12 nM) and stable inhibitor. AC inhibition increased cellular ceramide levels, decreased sphingosine 1-phosphate levels, and acted synergistically with several, albeit not all, antitumoral agents. The results suggest that AC-controlled sphingolipid metabolism may play an important role in the control of melanoma proliferation.
authors.affiliation: From the Department of Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, Genova 16163, Italy.
authors.forename: Natalia
authors.initials: N
authors.lastname: Realini
authors.affiliation: From the Department of Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, Genova 16163, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Palese
authors.affiliation: From the Department of Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, Genova 16163, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Pizzirani
authors.affiliation: From the Department of Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, Genova 16163, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pontis
authors.affiliation: From the Department of Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, Genova 16163, Italy.
authors.forename: Abdul
authors.initials: A
authors.lastname: Basit
authors.affiliation: From the Department of Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, Genova 16163, Italy, the Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen 2100, Denmark, and.
authors.forename: Anders
authors.initials: A
authors.lastname: Bach
authors.affiliation: the Departments Dermatology and.
authors.forename: Anand
authors.initials: A
authors.lastname: Ganesan
authors.affiliation: From the Department of Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, Genova 16163, Italy, Anatomy and Neurobiology, University of California, Irvine, California 92617 piomelli@uci.edu.
authors.forename: Daniele
authors.initials: D
authors.lastname: Piomelli
mesh_terms: D055573:Acid Ceramidase / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D002518:Ceramides / Q000737:chemistry; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000737:chemistry; D005347:Fibroblasts / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D056945:Hep G2 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D015603:Keratinocytes / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D008246:Lysophospholipids / Q000378:metabolism; D061986:MCF-7 Cells; D008544:Melanocytes / Q000166:cytology / Q000378:metabolism; D008545:Melanoma / Q000378:metabolism*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D010088:Oxidoreductases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051102:Serine C-Palmitoyltransferase / Q000378:metabolism; D015398:Signal Transduction; D012878:Skin Neoplasms / Q000378:metabolism*; D013107:Sphingolipids / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D014498:Uracil / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D002518:Ceramides; D004791:Enzyme Inhibitors; D008055:Lipids; D008246:Lysophospholipids; D034741:RNA, Small Interfering; D013107:Sphingolipids; C060506:sphingosine 1-phosphate; D014498:Uracil; D010088:Oxidoreductases; C108138:dihydroceramide desaturase; D051102:Serine C-Palmitoyltransferase; C526693:ASAH1 protein, human; D055573:Acid Ceramidase; D013110:Sphingosine
keywords: acid ceramidase; cancer biology; ceramide; enzyme inhibitor; melanoma; sphingolipid