title: N-(4-hydroxyphenyl)retinamide induces growth arrest and apoptosis in HTLV-I-transformed cells.
abstract: N-(4-hydroxyphenyl)retinamide (HPR) is a synthetic retinoid that inhibits growth and induces apoptosis in many human cell lines. We explored the effects of HPR on human T-cell lymphotropic virus type I (HTLV-I)-positive and HTLV-I-negative malignant T-cell lines, most of which are resistant to all-trans retinoic acid. Clinically achievable concentrations of HPR caused a dramatic inhibition of cell proliferation, G(0)/G(1) arrest, and massive apoptosis in all tested malignant T cells, while no effect was observed on resting or activated normal lymphocytes. Interestingly, HTLV-I-negative cell lines were significantly more sensitive to HPR compared to HTLV-I-positive and Tax-transfected cells. In HTLV-I-negative cells only, HPR-induced apoptosis was associated with ceramide accumulation, sharp decrease in mitochondrial membrane potential, and activation of caspases 8, 9 and 3, and could be partially reverted by the caspase inhibitor z-VAD suggesting that Tax protects infected cells from ceramide accumulation and caspase-mediated apoptosis. In HTLV-I-positive cells, HPR treatment rapidly induced proteasomal-mediated degradation of p21, downregulated cyclin D(1), and upregulated bax protein levels. These findings support a potential therapeutic role for HPR in both HTLV-I-associated adult T-cell leukemia/lymphoma (ATL) and HTLV-I-negative peripheral T-cell lymphomas.
authors.affiliation: Department of Biology, American University of Beirut, Beirut, Lebanon. darwichn@aub.edu.lb
authors.forename: N
authors.initials: N
authors.lastname: Darwiche
authors.forename: A
authors.initials: A
authors.lastname: Hatoum
authors.forename: G
authors.initials: G
authors.lastname: Dbaibo
authors.forename: H
authors.initials: H
authors.lastname: Kadara
authors.forename: R
authors.initials: R
authors.lastname: Nasr
authors.forename: G
authors.initials: G
authors.lastname: Abou-Lteif
authors.forename: R
authors.initials: R
authors.lastname: Bazzi
authors.forename: O
authors.initials: O
authors.lastname: Hermine
authors.forename: H
authors.initials: H
authors.lastname: de Thé
authors.forename: Ali
authors.initials: A
authors.lastname: Bazarbachi
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D056741:Cyclin D; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D017313:Fenretinide / Q000494:pharmacology*; D015368:Human T-lymphotropic virus 1 / Q000502:physiology*; D006801:Humans; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D013601:T-Lymphocytes / Q000378:metabolism / Q000473:pathology* / Q000821:virology; D014407:Tumor Cells, Cultured; D051028:bcl-2-Associated X Protein
chemical_list: D000970:Antineoplastic Agents; C494826:BAX protein, human; C493956:CDKN1A protein, human; D056741:Cyclin D; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D017313:Fenretinide; D020169:Caspases