N-(4-Hydroxyphenyl)retinamide increases dihydroceramide and synergizes with dimethylsphingosine to enhance cancer cell killing.
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 [3H]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.
Wang
Hongtao
H
Childrens Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
Maurer
Barry J
BJ
Liu
Yong-Yu
YY
Wang
Elaine
E
Allegood
Jeremy C
JC
Kelly
Samuel
S
Symolon
Holly
H
Liu
Ying
Y
Merrill
Alfred H
AH
Gouazé-Andersson
Valérie
V
Yu
Jing Yuan
JY
Giuliano
Armando E
AE
Cabot
Myles C
MC
D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D017313:Fenretinide / Q000494:pharmacology*; D006801:Humans; D009369:Neoplasms / Q000473:pathology*; D013107:Sphingolipids / Q000032:analysis; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors
D002518:Ceramides; D013107:Sphingolipids; C109343:dihydroceramide; D017313:Fenretinide; C061800:N,N-dimethylsphingosine; D013110:Sphingosine