This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Villani, M. G. Articles by Formelli, F. Search for Related Content PubMed PubMed Citation Articles by Villani, M. G. Articles by Formelli, F.

Identification of the Fenretinide Metabolite 4-Oxo-Fenretinide Present in Human Plasma and Formed in Human Ovarian Carcinoma Cells through Induction of Cytochrome P450 26A1

¹ Department of Experimental Oncology, Istituto Nazionale Tumori, Milan, Italy; ² Center of Excellence on Neurodegenerative Diseases, Study Center for the Biochemistry and Biotechnology of Glycolipids, University of Milan, Segrate Milan, Italy; and ³ Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, Ohio

Purpose: The synthetic retinoid fenretinide (4-HPR) exhibits preventive and therapeutic activity against ovarian tumors. An unidentified polar metabolite was previously found in 4-HPR-treated subjects and in A2780 human ovarian carcinoma cells continuously treated with 4-HPR (A2780/HPR). The metabolite and the enzyme involved in its formation in tumor cells are herein identified.

Experimental Design: The metabolite was identified by mass spectrometry in A2780/HPR cell extracts and in plasma from 11 women participating in a phase III trial and treated with 200 mg/d 4-HPR for 5 years. The expression of proteins involved in retinoid metabolism and transport, cytochrome P450 26A1 (CYP26A1), cellular retinol-binding protein I (CRBP-I), and cellular retinoic acid-binding protein I and II (CRABP-I, CRABP-II) were evaluated in tumor cells by reverse transcription-PCR and Western blot analyses. Overexpression of CYP26A1 and retinoic acid receptors (RARs) in A2780 cells were obtained by cDNAs transfection.

Results: The polar metabolite was 4-oxo-N-(4-hydroxyphenyl)retinamide (4-oxo-4-HPR) i.e., an oxidized form of 4-HPR with modification in position 4 of the cyclohexene ring. 4-oxo-4-HPR plasma levels were slightly lower (0.52 ± 0.17 µmol/L) than those of the parent drug (0.84 ± 0.53 µmol/L) and of the already identified metabolite N-(4-methoxyphenyl)retinamide (1.13 ± 0.85 µmol/L). In A2780/HPR cells continuously treated with 4-HPR and producing 4-oxo-4-HPR, CYP26A1 and CRBP-I were markedly up-regulated compared with A2780 untreated cells. In A2780 cells, not producing 4-oxo-4-HPR, overexpression of CYP26A1 caused formation of 4-oxo-4-HPR, which was associated with no change in 4-HPR sensitivity. Moreover, the addition of 4-oxo-4-HPR to A2780 cells inhibited cell proliferation. Elevated levels of CYP26A1 protein and metabolism of 4-HPR to 4-oxo-4-HPR were found in A2780 cells transfected with RARß and to a lesser extent in those transfected with RAR.

Conclusions: A new metabolite of 4-HPR, 4-oxo-4-HPR, present in human plasma and in tumor cells, has been identified. The formation of this biologically active metabolite in tumor cells was due to CYP26A1 induction and was influenced by RAR expression. Moreover evidence was provided that 4-HPR up-modulates the expression of CRBP-I transcript, which is lost during ovarian carcinogenesis.

This article has been cited by other articles:

				N. Colombo, F. Formelli, M. G. Cantu, G. Parma, M. Gasco, A. Argusti, A. Santinelli, R. Montironi, E. Cavadini, L. Baglietto, et al. A Phase I-II Preoperative Biomarker Trial of Fenretinide in Ascitic Ovarian Cancer. Cancer Epidemiol. Biomarkers Prev., October 1, 2006; 15(10): 1914 - 1919. [Abstract] [Full Text] [PDF]

				M. G. Villani, V. Appierto, E. Cavadini, A. Bettiga, A. Prinetti, M. Clagett-Dame, R. W. Curley, and F. Formelli 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. Cancer Res., March 15, 2006; 66(6): 3238 - 3247. [Abstract] [Full Text] [PDF]