TY - JOUR

T1 - Acid Ceramidase in Melanoma

T2 - EXPRESSION, LOCALIZATION, AND EFFECTS OF PHARMACOLOGICAL INHIBITION

AU - Realini, Natalia

AU - Palese, Francesca

AU - Pizzirani, Daniela

AU - Pontis, Silvia

AU - Basit, Abdul

AU - Bach, Anders

AU - Ganesan, Anand

AU - Piomelli, Daniele

N1 - © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

PY - 2016/1/29

Y1 - 2016/1/29

N2 - 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.

AB - 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.

KW - Acid Ceramidase

KW - Cell Line, Tumor

KW - Cell Proliferation

KW - Cell Survival

KW - Ceramides

KW - Down-Regulation

KW - Enzyme Inhibitors

KW - Fibroblasts

KW - Gene Expression Regulation, Neoplastic

KW - HCT116 Cells

KW - Hep G2 Cells

KW - Humans

KW - Inhibitory Concentration 50

KW - Keratinocytes

KW - Lipids

KW - Lysophospholipids

KW - MCF-7 Cells

KW - Melanocytes

KW - Melanoma

KW - Microscopy, Confocal

KW - Microscopy, Fluorescence

KW - Oxidoreductases

KW - RNA, Small Interfering

KW - Serine C-Palmitoyltransferase

KW - Signal Transduction

KW - Skin Neoplasms

KW - Sphingolipids

KW - Sphingosine

KW - Uracil

KW - Journal Article

U2 - 10.1074/jbc.M115.666909

DO - 10.1074/jbc.M115.666909

M3 - Journal article

C2 - 26553872

VL - 291

SP - 2422

EP - 2434

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 5

ER -