title: ZD1839 (IRESSA), an EGFR-selective tyrosine kinase inhibitor, enhances taxane activity in bcl-2 overexpressing, multidrug-resistant MCF-7 ADR human breast cancer cells.
abstract: Constitutive bcl-2 overexpression increases the tumorigenic and metastatic potential of doxorubicin-resistant, estrogen-independent, MCF-7 ADR human breast cancer cells. We evaluated the sensitivity to taxanes (paclitaxel, docetaxel and IDN 5109) of 2 bcl-2-overexpressing MCF-7 ADR clones and control neomycin-transfected MCF-7 ADR neo cells. The 2 bcl-2-overexpressing MCF-7 ADR clones were relatively resistant to all 3 taxanes, whereas the MCF-7 ADR neo cells were relatively resistant to paclitaxel and docetaxel, but sensitive to IDN 5109. We found that both MCF-7 ADR neo and bcl-2-overexpressing MCF-7 ADR clones express high levels of the epidermal growth factor receptor (EGFR) and its ligand, transforming growth factor-alpha (TGF-alpha). Therefore, we tested the growth inhibitory effect of ZD1839 (Iressa, AstraZeneca, Macclesfield, UK), an orally active, selective EGFR tyrosine kinase inhibitor (EGFR-TKI) that is in clinical development. ZD1839 inhibited the growth in soft agar of all 3 clones in a dose-dependent manner (IC(50) of approximately 0.1 microm). This effect was accompanied by a dose-dependent inhibition of EGFR tyrosine autophosphorylation and of the production of TGF-alpha, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF). To determine whether the blockade of EGFR signaling might affect the sensitivity of bcl-2-overexpressing MCF-7 ADR cells to taxanes, cells were treated with ZD1839 in combination with paclitaxel, docetaxel or IDN 5109, and dose-dependent cooperative growth inhibition as well as apoptosis potentiation were observed. Combined treatment with IDN 5109 and ZD1839 also resulted in a significant inhibition of bcl-2 expression in bcl-2-overexpressing MCF-7 ADR cells. These results demonstrate the ability of ZD1839 to overcome taxane resistance in a model of hormone-independent, multidrug-resistant, human breast cancer.
authors.affiliation: Dipartimento di Endocrinologia e Oncologia Molecolare e Clinica, Università di Napoli Federico II, Naples, Italy. fortunatociardiello@yahoo.com
authors.forename: Fortunato
authors.initials: F
authors.lastname: Ciardiello
authors.forename: Rosa
authors.initials: R
authors.lastname: Caputo
authors.forename: Gaetano
authors.initials: G
authors.lastname: Borriello
authors.forename: Donatella
authors.initials: D
authors.lastname: Del Bufalo
authors.forename: Annamaria
authors.initials: A
authors.lastname: Biroccio
authors.forename: Gabriella
authors.initials: G
authors.lastname: Zupi
authors.forename: A Raffaele
authors.initials: AR
authors.lastname: Bianco
authors.forename: Giampaolo
authors.initials: G
authors.lastname: Tortora
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D001952:Bridged-Ring Compounds / Q000627:therapeutic use*; D002455:Cell Division / Q000187:drug effects; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D000077156:Gefitinib; D006801:Humans; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D011799:Quinazolines / Q000627:therapeutic use*; D043823:Taxoids; D014162:Transfection; D016211:Transforming Growth Factor alpha / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D001952:Bridged-Ring Compounds; D004791:Enzyme Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D011799:Quinazolines; D043823:Taxoids; D016211:Transforming Growth Factor alpha; D016222:Fibroblast Growth Factor 2; C080625:taxane; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D000077156:Gefitinib