Saw. Fuqua et al., CONSTITUTIVE OVEREXPRESSION OF THE 27,000-DALTON HEAT-SHOCK PROTEIN IN LATE PASSAGE HUMAN BREAST-CANCER CELLS, Breast cancer research and treatment, 32(2), 1994, pp. 177-186
We present evidence that the mechanisms controlling induction of heat
shock transcription factors (HSFs) and mRNA expression of the 27,000 m
olecular weight heat shock protein, hsp27, are diverse in human breast
cancer cells. Heat shock accumulation of hsp27 RNA is associated with
the activation of HSF in MDA-MB-231 cells. We have later passage MCF-
7 breast cancer cell lines with elevated, constitutive expression of h
sp27 mRNA, perhaps due to hsp 27 gene amplification. Estradiol and hea
t shock treatment no longer affect the level of hsp27 mRNA in these ce
lls. Heat induction of HSF is inhibited in cells overexpressing hsp27,
although metal ions and amino acid analogs are still capable of activ
ating HSE These cells will provide a useful system for characterizing
alternative pathways in HSF inhibition and activation.