title: Rapamycin together with herceptin significantly increased anti-tumor efficacy compared to either alone in ErbB2 over expressing breast cancer cells.
abstract: The objective of this study was to assess the anti-tumor efficacy of rapamycin alone or in combination with herceptin in breast cancer. A total of 20 human breast cancer lines were examined for expression of various receptor tyrosine kinases and activation of their down stream signaling molecules, as well as for their invasion and colony forming ability. The ErbB2 and PI3 kinase pathway inhibitors were tested for the inhibition on breast cancer cell growth and tumor development. Seven of the 20 lines displayed an elevated level of ErbB2, others had varying level of EGF, IGF-1 or insulin receptor. Over 30% of the lines also had constitutive activation of Akt and MAP kinase. The lines displayed a wide range of colony forming and invasion ability. The PI3 kinase pathway inhibitors LY294002 and rapamycin inhibited the colony forming ability of all of the lines with the ErbB2 overexpressing lines having a higher sensitivity. A similar trend was observed for inhibition of invasion by LY294002. Rapamycin alone and additively together with herceptin inhibited the breast cancer cell growth especially in ErbB2 overexpressing cells. Rapamycin and herceptin synergistically inhibited tumor growth and endpoint tumor load in a xenograft model using a MCF-7 subline and in a MMTV-ErbB2 transgenic model. Rapamycin and herceptin significantly reduced the level of cyclin D1 and D3 and increased the cleavage of caspase 3 suggesting an increased apoptosis. Our results suggest that rapamycin together with herceptin has an enhanced anti-cancer effect and could be developed as an improved therapeutic regimen for breast cancer.
authors.affiliation: Department of Microbiology, Mount Sinai School of Medicine, New York 10029, NY, USA. lu-hai.wang@mssm.edu
authors.forename: Lu-Hai
authors.initials: LH
authors.lastname: Wang
authors.forename: Joseph L-K
authors.initials: JL
authors.lastname: Chan
authors.forename: Wei
authors.initials: W
authors.lastname: Li
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019938:Cyclin D1 / Q000378:metabolism; D056743:Cyclin D3; D016213:Cyclins / Q000378:metabolism; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009361:Neoplasm Invasiveness / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D053148:Caspase 3; D019938:Cyclin D1; D056743:Cyclin D3; D016213:Cyclins; D036341:Intercellular Signaling Peptides and Proteins; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D020794:Receptor Protein-Tyrosine Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases; D020123:Sirolimus; C534696:CCND3 protein, human; C534697:Ccnd3 protein, mouse; C434665:herstatin