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

Maria Grazia Villani, Valentina Appierto, Elena Cavadini, Arianna Bettiga, Alessandro Prinetti, Margaret Clagett-Dame, Robert W. Curley, Franca Formelli

Research output: Contribution to journalArticlepeer-review

Abstract

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 G1 phase of the cell cycle, 4-oxo-4-HPR caused a marked accumulation of cells in G2-M. This effect was associated with a reduction in the expression of regulatory proteins of G2-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.

Original languageEnglish
Pages (from-to)3238-3247
Number of pages10
JournalCancer Research
Volume66
Issue number6
DOIs
Publication statusPublished - Mar 15 2006

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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