Geldanamycin inhibits proliferation and motility of Her2/neu-overexpressing SK-Br3 breast cancer cells

Objective: Benzoquinone ansamycin antibiotic, geldanamycin (GA), is a new anticancer agent that could inhibit Hsp90 by occupying its NH2-terminal ATP-binding site. This study was to investigate the antitumor efficacy of GA on Her2/neu tyrosine kinase overexpressing human breast cancer cell line SKBr3. Methods: The degradation of Her2/neu tyrosine kinase was analyzed by Western blotting, the proliferation index was determined by MTT assay, cell cycle distribution was detected by flow cytometry, Cyclin D1 mRNA transcription was measured by RT-PCR and real-time PCR, and cell motility was evaluated by the cell culture insert model. Results: GA induced a dose- and a time-dependent degradation of the Her2/ neu tyrosine kinase protein and concurrently, the inhibition of cancer cell proliferation. The antitumor effects mediated by GA included: GA treatment decreased the survival rates of cancer cells, and led to a dose-dependent G₁ arrest. Furthermore, this antitumor effect was proved to be related to declined transcription of Cyclin D1. Concurrently, the motility of cancer cells was reduced by GA. Conclusion: GA treatment could induce the degradation of Her2/neu tyrosine kinase efficiently, inhibit cancer cell proliferation and reduce motility in Her2/neu tyrosine kinase overexpressed human breast cancer cell line SKBr3.