Constitutive overexpression of the 27,000 dalton heat shock protein in late passage human breast cancer cells.
We present evidence that the mechanisms controlling induction of heat shock transcription factors (HSFs) and mRNA expression of the 27,000 molecular 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 hsp27 mRNA, perhaps due to hsp27 gene amplification. Estradiol and heat shock treatment no longer affect the level of hsp27 mRNA in these cells. Heat induction of HSF is inhibited in cells overexpressing hsp27, although metal ions and amino acid analogs are still capable of activating HSF. These cells will provide a useful system for characterizing alternative pathways in HSF inhibition and activation.
Fuqua
S A
SA
University of Texas Health Science Center, Department of Medicine Oncology, San Antonio 78284-7884.
Benedix
M G
MG
Krieg
S
S
Weng
C N
CN
Chamness
G C
GC
Oesterreich
S
S
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002455:Cell Division; D002893:Chromosomes, Human, Pair 3; D004273:DNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D004958:Estradiol / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006358:Hot Temperature; D006801:Humans; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics
D004273:DNA, Neoplasm; D006360:Heat-Shock Proteins; D009363:Neoplasm Proteins; D004958:Estradiol