title: HER2/neu reduces the apoptotic effects of N-(4-hydroxyphenyl)retinamide (4-HPR) in breast cancer cells by decreasing nitric oxide production.
abstract: The retinoid N-(4-hydroxyphenyl)retinamide (4-HPR also known as fenretinide) is a potent inducer of apoptosis in breast cancer cells. We observed a 4.5-fold reduction in 4-HPR-mediated apoptosis in MCF-7 breast cancer cells transfected with HER2/neu (MCF-7/HER2) as compared with the parental MCF-7 (MCF-7/WT) cells. Blocking HER2/neu with trastuzumab (Herceptin) led to a six-fold increase in 4-HPR-induced apoptosis in HER2/neu-overexpressing cells. These data indicate that HER2/neu reduces the sensitivity of breast cancer cells to 4-HPR. We showed previously that nitric oxide (NO) is essential for 4-HPR to induce apoptosis in breast cancer cells. The inhibitory effects of the 4-HPR and trastuzumab combination correlated with the amount of NO produced in HER2/neu-overexpressing cells. When a NO synthase (NOS) inhibitor was used to block NO production, decreased apoptosis by the 4-HPR and trastuzumab combination was observed. Furthermore, 4-HPR-mediated NOSII expression was lower in MCF-7/HER2 than MCF-7/WT cells, but was increased by trastuzumab in HER2/neu-overexpressing cells. Here we report the novel findings that HER2/neu reduces the ability of 4-HPR to induce apoptosis in breast cancer cells, and that one mechanism by which HER2/neu increases the resistance of breast cancer cells to 4-HPR is by decreasing NOSII-mediated NO production.
authors.affiliation: Department of Bioimmunotherapy, Section of Immunobiology and Drug Carriers, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Ann-Marie
authors.initials: AM
authors.lastname: Simeone
authors.forename: Lyle David
authors.initials: LD
authors.lastname: Broemeling
authors.forename: Josh
authors.initials: J
authors.lastname: Rosenblum
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Tari
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D002455:Cell Division; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017313:Fenretinide / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D000068878:Trastuzumab; D014212:Tretinoin / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D017313:Fenretinide; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; D014212:Tretinoin