Changes in the localization of heat shock protein 72 correlated with development of thermotolerance in human esophageal cancer cell line.
BACKGROUND
The aim of this study was to investigate the relationship between the changes in the localization of heat shock proteins (Hsps) and acquisition of thermotolerance.


METHODS
A human esophageal cancer cell line was used. Fractionated heat treatment with different recovery times was performed to develop thermotolerance. Changes in the localization and the expression of Hsps were examined by the immunofluorescence and immunoblot analysis. In order to inhibit Hsps induction, Hsp inhibitor, KNK437, was used. In addition, changes in susceptibility of apoptosis induction were also evaluated in thermotolerant or non-thermotolerant cells.


RESULTS
Thermotolerance reached its peak at the recovery time of 120 minutes after the first heat and maximum thermotolerance was observed in consistence with the timing of appearance of cytoplasmic Hsp72. Suppression of cytoplasmic Hsp72 positivity caused by KNK437 resulted in inhibition of acquisition of thermotolerance. Caspase-3 activation and PARP cleavage, that were suppressed in thermotolerant cells, re-appeared by using KNK437, in combination with heat.


CONCLUSIONS
The cytoplasmic localization of Hsp72 might be correlated with the development of thermotolerance.
Department of Radiology and Radiation Oncology, Gunma University Faculty of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8551, Japan.
Tetsuo
T
Nonaka
Tetsuo
T
Akimoto
Norio
N
Mitsuhashi
Yoshio
Y
Tamaki
Shinichi
S
Yokota
Takashi
T
Nakano
D000064:Acclimatization / Q000187:drug effects / Q000502:physiology*; D017209:Apoptosis / Q000187:drug effects; D001559:Benzhydryl Compounds / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism / Q000473:pathology; D004938:Esophageal Neoplasms; D019084:Fluorescent Antibody Technique, Indirect; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D021381:Protein Transport; D011760:Pyrrolidinones / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D001559:Benzhydryl Compounds; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C410027:KNK 437; D011760:Pyrrolidinones