Heat shock protein 90 (Hsp90) is a molecular chaperone that maintains the structural and functional integrity of various protein clients involved in multiple oncogenic signaling pathways. Hsp90 holds a prominent role in tumorigenesis, as numerous members of its broad clientele are involved in the generation of the hallmark traits of cancer.
17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG) specifically targets Hsp90 and interferes with its function as a molecular chaperone, impairing its intrinsic ATPase activity and undermining proper folding of multiple protein clients. In this study, we have examined the effects of 17-DMAG on the regulation of Hsp90-dependent tumorigenic signaling pathways directly implicated in cell cycle progression, survival, and motility of human urinary bladder cancer cell lines. We have used MTT-based assays, FACS analysis, Western blotting, semiquantitative PCR (sqPCR), immunofluorescence, and scratch-wound assays in RT4 (p53(wt)), RT112 (p53(wt)), T24 (p53(mt)), and TCCSUP (p53(mt)) human urinary bladder cancer cell lines. We have demonstrated that, upon exposure to 17-DMAG, bladder cancer cells display prominent cell cycle arrest and commitment to apoptotic and autophagic cell death, in a dose-dependent manner. Furthermore, 17-DMAG administration induced pronounced downregulation of multiple Hsp90 protein clients and other downstream oncogenic effectors, therefore causing inhibition of cell proliferation and decline of cell motility due to the molecular "freezing" of critical cytoskeletal components. In toto, we have clearly demonstrated the dose-dependent and cell type-specific effects of 17-DMAG on the hallmark traits of cancer, appointing Hsp90 as a key molecular component in bladder cancer targeted therapy.
Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine. 2015 Dec 11 [Epub ahead of print]
Panagiotis K Karkoulis, Dimitrios J Stravopodis, Gerassimos E Voutsinas
Laboratory of Environmental Mutagenesis and Carcinogenesis, Institute of Biosciences and Applications, National Center for Scientific Research (NCSR) "Demokritos", 15310, Athens, Greece. , Department of Cell Biology and Biophysics, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, 15784, Athens, Greece. , Laboratory of Environmental Mutagenesis and Carcinogenesis, Institute of Biosciences and Applications, National Center for Scientific Research (NCSR) "Demokritos", 15310, Athens, Greece.