4-oxo-fenretinide, a recently identified fenretinide metabolite, induces marked G2-M cell cycle arrest and apoptosis in fenretinide-sensitive and fenretinide-resistant cell lines.
4-oxo-N-(4-hydroxyphenyl)retinamide (4-oxo-4-HPR) is a recently identified metabolite of fenretinide (4-HPR). We explored the effectiveness of 4-oxo-4-HPR in inducing cell growth inhibition in ovarian, breast, and neuroblastoma tumor cell lines; moreover, we investigated the molecular events mediating this effect in two ovarian carcinoma cell lines, one sensitive (A2780) and one resistant (A2780/HPR) to 4-HPR. 4-oxo-4-HPR was two to four times more effective than 4-HPR in most cell lines, was effective in both 4-HPR-sensitive and 4-HPR-resistant cells, and, in combination with 4-HPR, caused a synergistic effect. The tumor growth-inhibitory effects of 4-oxo-4-HPR seem to be independent of nuclear retinoid receptors (RAR), as indicated by the failure of RAR antagonists to inhibit its effects and by its poor ability to bind and transactivate RARs. Unlike 4-HPR, which only slightly affected the G(1) phase of the cell cycle, 4-oxo-4-HPR caused a marked accumulation of cells in G(2)-M. This effect was associated with a reduction in the expression of regulatory proteins of G(2)-M (cyclin-dependent kinase 1 and cdc25c) and S (cyclin A) phases, and with an increase in the expression of apoptosis-related proteins, such as p53 and p21. Apoptosis was induced by 4-oxo-4-HPR in both 4-HPR-sensitive and 4-HPR-resistant cells and involved activation of caspase-3 and caspase-9 but not caspase-8. We also showed that 4-oxo-4-HPR, similarly to 4-HPR, increased reactive oxygen species generation and ceramide levels by de novo synthesis. In conclusion, 4-oxo-4-HPR is an effective 4-HPR metabolite that might act as therapeutic agent per se and, when combined with 4-HPR, might improve 4-HPR activity or overcome 4-HPR resistance.
Chemoprevention Unit, Department of Experimental Oncology, Istituto Nazionale Tumori, Milan, Italy.
Maria Grazia
MG
Villani
Valentina
V
Appierto
Elena
E
Cavadini
Arianna
A
Bettiga
Alessandro
A
Prinetti
Margaret
M
Clagett-Dame
Robert W
RW
Curley
Franca
F
Formelli
D000970:Antineoplastic Agents / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000096:biosynthesis; D002455:Cell Division / Q000187:drug effects*; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D017313:Fenretinide / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*; D016195:G2 Phase / Q000187:drug effects*; D006801:Humans; D009447:Neuroblastoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism
C494898:4-oxofenretinide; D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D002518:Ceramides; D017382:Reactive Oxygen Species; D017313:Fenretinide; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases