N-(4-Hydroxyphenyl)retinamide increases dihydroceramide and synergizes with dimethylsphingosine to enhance cancer cell killing

• Published in: Molecular cancer therapeutics 2008-09, Vol.7 (9), p.2967-2976
• Main Authors: Wang, Hongtao, Maurer, Barry J, Liu, Yong-Yu, Wang, Elaine, Allegood, Jeremy C, Kelly, Samuel, Symolon, Holly, Liu, Ying, Merrill, Jr, Alfred H, Gouazé-Andersson, Valérie, Yu, Jing Yuan, Giuliano, Armando E, Cabot, Myles C
• Format: Article
• Language: English
• Subjects: 4-HPR; Cell Death - drug effects; Cell Line, Tumor; Ceramides - metabolism; dihydro(ceramide); dimethylsphingosine; Dose-Response Relationship, Drug; Drug Synergism; fenretinide; Fenretinide - pharmacology; Humans; Neoplasms - pathology; sphinganine; Sphingolipids - analysis; Sphingosine - analogs & derivatives; Sphingosine - pharmacology; Time Factors
• ISSN: 1535-7163; 1538-8514
• DOI: 10.1158/1535-7163.MCT-08-0549

Fenretinide [ N -(4-hydroxyphenyl)retinamide (4-HPR)] is cytotoxic in many cancer cell types. Studies have shown that elevation of ceramide species plays a role in 4-HPR cytotoxicity. To determine 4-HPR activity in a multidrug-resistant cancer cell line as well as to study ceramide metabolism, MCF-7/AdrR cells (redesignated NCI/ADR-RES) were treated with 4-HPR and sphingolipids were analyzed. TLC analysis of cells radiolabeled with [ 3 H]palmitic acid showed that 4-HPR elicited a dose-responsive increase in radioactivity migrating in the ceramide region of the chromatogram and a decrease in cell viability. Results from liquid chromatography/electrospray tandem mass spectrometry revealed large elevations in dihydroceramides ( N -acylsphinganines), but not desaturated ceramides, and large increases in complex dihydrosphingolipids (dihydrosphingomyelins, monohexosyldihydroceramides), sphinganine, and sphinganine 1-phosphate. To test the hypothesis that elevation of sphinganine participates in the cytotoxicity of 4-HPR, cells were treated with the sphingosine kinase inhibitor d -erythro- N,N -dimethylsphingosine (DMS), with and without 4-HPR. After 24 h, the 4-HPR/DMS combination caused a 9-fold increase in sphinganine that was sustained through +48 hours, decreased sphinganine 1-phosphate, and increased cytotoxicity. Increased dihydrosphingolipids and sphinganine were also found in HL-60 leukemia cells and HT-29 colon cancer cells treated with 4-HPR. The 4-HPR/DMS combination elicited increased apoptosis in all three cell lines. We propose that a mechanism of 4-HPR–induced cytotoxicity involves increases in dihydrosphingolipids, and that the synergy between 4-HPR and DMS is associated with large increases in cellular sphinganine. These studies suggest that enhanced clinical efficacy of 4-HPR may be realized through regimens containing agents that modulate sphingoid base metabolism. [Mol Cancer Ther 2008;7(9):2967–76]