title: Overexpression of HER2 modulates bcl-2, bcl-XL, and tamoxifen-induced apoptosis in human MCF-7 breast cancer cells.
abstract: Overexpression of HER2 in estrogen receptor (ER)-positive human breast tumors has been associated with resistance to endocrine therapy. Here we investigated the effects of HER2 on expression of apoptotic pathways and modulation of tamoxifen-induced apoptosis in ER-positive MCF-7 breast cancer cells. We report that HER2 overexpression in MCF-7 cells is accompanied by up-regulation of antiapoptotic Bcl-2 and Bcl-XL proteins and suppression of tamoxifen-induced apoptosis. In addition, human tumor cell lines that are both ER positive and overexpress HER2 also express enhanced levels of Bcl-2 compared to cells that are either ER positive or overexpress HER2 alone. Our findings suggest that possible deregulation of antiapoptotic Bcl-2 and Bcl-XL may be associated with the enhanced survival of HER2-overexpressing and ER-positive breast cancer cells treated with antiestrogens.
authors.affiliation: Departments of Medicine and Cellular, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA.
authors.forename: R
authors.initials: R
authors.lastname: Kumar
authors.forename: M
authors.initials: M
authors.lastname: Mandal
authors.forename: A
authors.initials: A
authors.lastname: Lipton
authors.forename: H
authors.initials: H
authors.lastname: Harvey
authors.forename: C B
authors.initials: CB
authors.lastname: Thompson
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000737:chemistry / Q000188:drug therapy* / Q000473:pathology; D004965:Estrogen Antagonists / Q000494:pharmacology*; D005260:Female; D006801:Humans; D011518:Proto-Oncogene Proteins / Q000032:analysis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000502:physiology*; D011960:Receptors, Estrogen / Q000032:analysis; D013629:Tamoxifen / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
chemical_list: D004965:Estrogen Antagonists; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D013629:Tamoxifen; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C494811:BCL2L1 protein, human