title: p185c-erbB-2 signal enhances cisplatin-induced cytotoxicity in human breast carcinoma cells: association between an oncogenic receptor tyrosine kinase and drug-induced DNA repair.
abstract: The c-erbB-2 (HER-2/neu) protooncogene encodes an M(r) 185,000 transmembrane glycoprotein with intrinsic tyrosine kinase activity. Agonistic antibodies against p185c-erbB-2 enhance the cytotoxic effect of the DNA alkylator, cisplatin, against c-erbB-2-overexpressing human carcinoma cells (Hancock et al., Cancer Res., 51:4575-4580, 1991). We have studied the possible association between receptor signal transduction and cisplatin-mediated cytotoxicity utilizing the SKBR-3 human breast cancer cell line and the anti-p185 TAb 250 IgG1. TAb 250 induced tyrosine phosphorylation of p185 and the receptor substrate phospholipase C-gamma 1, as well as rapid association of these molecules in vivo. Simultaneously with phosphorylation, phospholipase C-gamma 1 catalytic activity measured in a [3H]phosphatidylinositol-4,5-bisphosphate hydrolysis assay was increased 61 +/- 12% above control. Preincubation of SKBR-3 cells with the tyrosine kinase inhibitor tyrphostin 50864-2 abrogated the enhancement of drug-mediated cell kill induced by TAb 250. The supraadditive drug/antibody effect was not seen in SKBR-3 cells with TAb 263, an anti-p185 IgG1 that does not induce receptor signaling or with TAb 250 in MDA-468 breast cancer cells which do not overexpress c-erbB-2. In addition, transforming growth factor-alpha increased cisplatin-induced cytotoxicity against NIH 3T3 cells overexpressing an epidermal growth factor receptor/c-erbB-2 chimera. Cellular uptake or efflux of [195mPt]cisplatin by SKBR-3 cells was not altered by TAb 250. Finally, simultaneous treatment of SKBR-3 cells with TAb 250 and cisplatin increased cisplatin/DNA intrastrand adduct formation and delayed the rate of adduct decay. Taken together these data support a direct association between p185c-erbB-2 signal transduction and inhibition of cisplatin-induced DNA repair.
authors.affiliation: Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee.
authors.forename: C L
authors.initials: CL
authors.lastname: Arteaga
authors.forename: A R
authors.initials: AR
authors.lastname: Winnier
authors.forename: M C
authors.initials: MC
authors.lastname: Poirier
authors.forename: D M
authors.initials: DM
authors.lastname: Lopez-Larraza
authors.forename: L K
authors.initials: LK
authors.lastname: Shawver
authors.forename: S D
authors.initials: SD
authors.lastname: Hurd
authors.forename: S J
authors.initials: SJ
authors.lastname: Stewart
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002945:Cisplatin / Q000378:metabolism / Q000494:pharmacology*; D004260:DNA Repair / Q000187:drug effects*; D066246:ErbB Receptors / Q000502:physiology*; D005260:Female; D006801:Humans; D010766:Phosphorylation; D011493:Protein Kinase C / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D018719:Erb-b2 Receptor Tyrosine Kinases; D015398:Signal Transduction / Q000187:drug effects*; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D002945:Cisplatin; D066246:ErbB Receptors; D011493:Protein Kinase C; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases