Expression of hsp90 and cyclin D1 in human breast cancer

The integral roles of heat shock proteins (hsps) in the cell cycle and in m ultistep processes leading to tumorigenesis have been implied. We examined the expression of hsp90 alpha, hsp90 beta and cyclin D1 in human breast can cer. Levels of mRNAs coding for hsp90 alpha and cyclin D1 were significantl y higher in cancer tissues than in non-cancer tissues. Moreover, there was a close relationship between the extent of the two mRNA levels, suggesting that increased expression of hsp90 alpha, an isoform of the hsp90 family, i s associated with the proliferation of human breast cancer. Hsp90 beta was expressed in cancer cells, but not associated with cell proliferation. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.