title: Effects of retinoic acid and fenretinide on the c-erbB-2 expression, growth and cisplatin sensitivity of breast cancer cells.
abstract: We investigated the effects of all-trans retinoic acid (ATRA) and fenretinide (4-HPR) on c-erbB-2 expression in SK-BR-3, BT-474 and MCF-7 breast cancer cells and on the growth, differentiation, apoptosis and cisplatin (CDDP) sensitivity of SK-BR-3 cells. It has been reported that oestrogen inhibits c-erbB-2 in oestrogen receptor-positive breast cancer cells. Using ELISA, Western and Northern analysis we have demonstrated that ATRA and 4-HPR exert similar effects down-regulating c-erbB-2 protein and mRNA in c-erbB-2-overexpressing SK-BR-3 and BT-474 and in normally expressing MCF-7 cells. Both retinoids inhibit SK-BR-3 cell growth. ATRA induces cellular enlargement and flattening, suggesting epithelial differentiation. 4-HPR causes nuclear and cytoplasmic condensation, DNA fragmentation and externalization of phosphatidylserine, indicating apoptosis. c-erbB-2 expression/activity has been linked to sensitivity against CDDP. Therefore, combinations of ATRA or 4-HPR with CDDP were tested for their anti-proliferative activity. Retinoid-conditioned cells were either exposed to retinoid and CDDP (schedule I, 'continuous retinoid treatment') or to CDDP alone (schedule II, 'retinoid pretreatment'). This retinoid-conditioning followed by CDDP +/- retinoid yields stronger growth inhibition compared with unconditioned cells, which were exposed to CDDP +/- retinoid (schedule III, 'no retinoid pretreatment'). The inefficacy of schedule III indicates that retinoid-conditioning is essential for the improvement of the antiproliferative effect. The interactions in schedules I and II are synergistic for ATRA and CDDP, but slightly antagonistic for 4-HPR and CDDR However, 4-HPR + CDDP is more effective in growth inhibition than each drug alone.
authors.affiliation: Laboratory for Cell Growth and Differentiation, Department of Internal Medicine I, University of Vienna, Austria.
authors.lastname: Grunt ThW
authors.forename: E
authors.initials: E
authors.lastname: Dittrich
authors.forename: M
authors.initials: M
authors.lastname: Offterdinger
authors.forename: S M
authors.initials: SM
authors.lastname: Schneider
authors.forename: Ch
authors.initials: Ch
authors.lastname: Dittrich
authors.forename: H
authors.initials: H
authors.lastname: Huber
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D002945:Cisplatin / Q000494:pharmacology; D053938:DNA Fragmentation; D004273:DNA, Neoplasm; D015536:Down-Regulation; D005260:Female; D017313:Fenretinide / Q000494:pharmacology; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D002945:Cisplatin; D004273:DNA, Neoplasm; D017313:Fenretinide; D009363:Neoplasm Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D014212:Tretinoin