title: Inhibitory effects of the combination of HER-2 antisense oligonucleotide and chemotherapeutic agents used for the treatment of human breast cancer.
abstract: Poor response to chemotherapy in patients with breast cancer is often associated with overexpression of HER-2/neu. Interference with HER-2 mRNA translation by means of antisense oligonucleotides might improve the efficacy of chemotherapy. To test this hypothesis, eight breast cancer cell lines and a normal human fibroblast cell line were examined for their level of HER-2 expression, their sensitivity to phosphorothioate antisense oligonucleotides (AS HER-2 ODN), and to various chemotherapeutic agents, and the combination of the two. No correlation was found between the intrinsic HER-2 level and either the sensitivity to a particular chemotherapeutic agent alone, or the amount of growth inhibition observed with a specific AS HER-2 ODN concentration. Although sequence specificity and extent of AS HER-2 ODN inhibition of HER-2 synthesis were somewhat higher in the HER-2 overexpressing MDA-MB-453 and SK-BR-3 cells, we found that antisense treatment significantly sensitized all of the breast cancer cells, even MDA-MB-231 and MDA-MB-435 cells, with approximately basal levels of HER-2, to various chemotherapeutic agents. In addition, the combination of AS HER-2 ODN and taxol was shown to synergistically induce apoptosis in MDA-MB-435. These results demonstrate that overexpression of HER-2 would not be a prerequisite for the effective use of AS HER-2 ODN as a combination treatment modality for breast cancer and suggest that the use of AS HER-2 ODN, as part of a combination treatment modality, need not be limited to breast tumors that display elevated levels of HER-2.
authors.affiliation: Departments of Oncology and Otolaryngology, Lombardi Cancer Center, Georgetown University Medical Center, Washington, DC 20007, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Rait
authors.forename: K F
authors.initials: KF
authors.lastname: Pirollo
authors.forename: V
authors.initials: V
authors.lastname: Rait
authors.forename: J E
authors.initials: JE
authors.lastname: Krygier
authors.forename: L
authors.initials: L
authors.lastname: Xiang
authors.forename: E H
authors.initials: EH
authors.lastname: Chang
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D004359:Drug Therapy, Combination; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D016376:Oligonucleotides, Antisense; D011065:Poly(ADP-ribose) Polymerases; D019253:Proto-Oncogene Proteins c-bcl-2; D018719:Erb-b2 Receptor Tyrosine Kinases