Thermotolerance and heat shock protein induction by slow rates of heating

Robin L. Anderson, Terence S. Herman, Ine Van Kersen, George M. Hahn

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The magnitude of thermotolerance and the level of heat shock protein (HSP) expression have been measured in Chinese hamster ovary cells after gradual temperature transients from 37° or 39° to 42° or 43°C. When the level of thermotolerance was measured by clonogenic survival after challenging temperatures between 42° and 43°, substantial thermotolerance was observed. However, when the challenging temperature was raised to 45°C, proportionally less thermotolerance was apparent. Heat shock proteins were quantitated by scanning densitometry of radiographs and, in the case of HSP 70, by immunoassay. Scanning densitometry revealed that low levels of heat shock proteins were synthesized during the heating gradients, but less than after a heat shock at 45°C that delivered an equivalent heat dose. The immunoassay of HSP 70 levels measures both pre-existing and newly synthesized protein, and showed that there was no net increase in HSP 70 during two of the heating gradients tested, despite the increase in synthesis noted on the gels. Higher turnover of HSP 70 at the elevated temperatures possibly accounted for the failure to detect a net gain in total protein. In contrast, the total amount of HSP 70 doubled during the 6 hr following a heat shock of 45° for 10 min, an equivalent heat dose to one of the gradients where no net increase in HSP 70 was measured by immunoassay. It appears, then, that tolerance to hyperthemia at 43°C or below may occur under some conditions in the absence of elevated levels of HSP 70, but tolerance to higher temperatures is more closely correlated with increased levels of heat shock proteins. However, even at higher temperatures, our data show disparities between the levels of HSP measured and the thermotolerance expressed.

Original languageEnglish (US)
Pages (from-to)717-725
Number of pages9
JournalInternational journal of radiation oncology, biology, physics
Volume15
Issue number3
DOIs
StatePublished - Sep 1988
Externally publishedYes

Keywords

  • Chinese hamster ovary cells
  • Heat shock proteins
  • Slow heating
  • Thermotolerance

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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