title: Granulocyte-colony stimulating factor upregulates ErbB2 expression on breast cancer cell lines and converts primary resistance to trastuzumab.
abstract: The recombinant monoclonal antibody trastuzumab has antiproliferative effect on breast cancer (BC) cells with ErbB2 overexpression. We postulated that a mechanism able to modify ErbB2 expression enhances the antitumor effect of trastuzumab. We analyzed whether granulocyte-colony stimulating factor (G-CSF), widely used in adjuvant cancer therapy to alleviate chemotherapy-induced myelotoxicity, could influence ErbB2 expression in BC cells and patients. The expression of ErbB2 (Herceptest) was analyzed in four BC cell lines (BT474, SKBR3, ZR75.1, and T47D) treated with G-CSF and in five samples biopsies from BC patients subjected to G-CSF rescue after chemotherapy. The effects of G-CSF and trastuzumab alone or their combination on cell growth and apoptosis were investigated. G-CSF receptor was detected on all cell lines and BC patients. G-CSF induced upregulation of ErbB2 in SKBR3, ZR75, and T47D cells. This modulation was not associated with an increase in tumor cell growth in vitro. Trastuzumab alone inhibited colony formation in soft agar but did not induce apoptosis on BC cells with no or low ErbB2 genomic amplification. The combination of trastuzumab and G-CSF enhanced the inhibition of tumor colony formation and induced apoptosis on these cells. This effect was further increased by G-CSF pretreatment. Five of nine BC patients showed an increase of Herceptest score after G-CSF administration. G-CSF treatment increases ErbB2 expression in vitro and in vivo enhancing the activity of trastuzumab on BC cell lines inducing apoptosis of BC cells with low or no ErbB2 genomic amplification.
authors.affiliation: Department of Medical Oncology, University of Torino Medical School, Institute for Cancer Research and Treatment, Candiolo, Torino, Italy. giuliana.cavalloni@ircc.it
authors.forename: Giuliana
authors.initials: G
authors.lastname: Cavalloni
authors.forename: Ivana
authors.initials: I
authors.lastname: Sarotto
authors.forename: Ymera
authors.initials: Y
authors.lastname: Pignochino
authors.forename: Loretta
authors.initials: L
authors.lastname: Gammaitoni
authors.forename: Giorgia
authors.initials: G
authors.lastname: Migliardi
authors.forename: Luca
authors.initials: L
authors.lastname: Sgro
authors.forename: Wanda
authors.initials: W
authors.lastname: Piacibello
authors.forename: Mauro
authors.initials: M
authors.lastname: Risio
authors.forename: Massimo
authors.initials: M
authors.lastname: Aglietta
authors.forename: Francesco
authors.initials: F
authors.lastname: Leone
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D018734:Genes, erbB-2; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000032:analysis; D000068878:Trastuzumab; D015854:Up-Regulation
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D016179:Granulocyte Colony-Stimulating Factor; D000068878:Trastuzumab