title: Combined inhibitory effect of formestane and herceptin on a subpopulation of CD44+/CD24low breast cancer cells.
abstract: In breast cancer, stromal cells surrounding cancer epithelial cells can influence phenotype by producing paracrine factors. Among many mediators of epithelial-stromal interactions, aromatase activity is perhaps one of the best studied. Clinical data suggest that estrogen-independent signaling leads to increased proliferation even during therapy with aromatase inhibitors (AIs). Molecular mechanism of crosstalk between the estrogen receptor (ER) and the epidermal growth factor receptor (HER) family have been implicated in resistance to endocrine therapy, but this interaction is unclear. The ability of aromatase to induce estradiol biosynthesis provides a molecular rationale to combine agents that target aromatase activity and the HER pathway. We targeted stromal-epithelial interactions using formestane, which exerts antiaromatase activity, combined with the monoclonal anti-HER2 antibody herceptin, in a subpopulation of CD44+/CD24low cells sorted from epithelial-mesenchymal co-cultures of breast cancer tissues. The growth inhibition was respectively 16% (P < 0.01) in the response to herceptin, 25% to formestane (P < 0.01), and 50% (P < 0.001) with the combination of the two drugs, suggesting that herceptin cooperates with formestane-induced inhibition of aromatase and this effect could be mediated through HER family receptors. In cells which expressed ERalpha, formestane/herceptin combination suppressed the mRNA expression of aromatase and HER2 and decreased cyclin D1 expression. These results show that combination therapies involving AIs and anti-HER2 can be efficacious for the treatment of cancer in experimental models and suggest that subtyping breast tumors gives useful information about response to treatment.
authors.affiliation: Department of Cellular and Molecular Biology and Pathology L. Califano, University of Naples Federico II, Naples, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Cavaliere
authors.forename: Sara
authors.initials: S
authors.lastname: Corvigno
authors.forename: Mario
authors.initials: M
authors.lastname: Galgani
authors.forename: Gennaro
authors.initials: G
authors.lastname: Limite
authors.forename: Agostina
authors.initials: A
authors.lastname: Nardone
authors.forename: Bianca Maria
authors.initials: BM
authors.lastname: Veneziani
mesh_terms: D000735:Androstenedione / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001141:Aromatase / Q000378:metabolism; D047072:Aromatase Inhibitors / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000276:immunology / Q000473:pathology; D051927:CD24 Antigen / Q000235:genetics / Q000276:immunology*; D045744:Cell Line, Tumor; D017931:DNA Primers; D066246:ErbB Receptors / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics / Q000276:immunology*; D012334:RNA, Neoplasm / Q000235:genetics; D020239:Receptor Cross-Talk; D011960:Receptors, Estrogen / Q000187:drug effects / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000068878:Trastuzumab; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D047072:Aromatase Inhibitors; D051927:CD24 Antigen; D017931:DNA Primers; D018960:Hyaluronan Receptors; D012334:RNA, Neoplasm; D011960:Receptors, Estrogen; D000735:Androstenedione; D001141:Aromatase; D066246:ErbB Receptors; D000068878:Trastuzumab; C014594:formestane