The overall focus of this project has been the study of mechanisms of heat protection and thermotolerance. We have characterized heat protection by polyhydroxy compounds, principally polyols and sugars and studied induction of thermotolerance by several thiol-active compounds. Based on our data, we suggested a mechanism for thermotolerance that is based on the synthesis of endogenous heat protectors, such as glycoproteins. Proposed experiments will extend and test these concepts in 3 specific aims: 1. Heat protection studies with polyols and sugars will be extended to include: amino acids; sugar phosphates; high- molecular weight compounds, e.g., polysaccharides and polypeptides; and physiological glycoproteins, known to play a role in thermal biology. 2. Proposed thermotolerance induction studies will utilize the technique of microinjection to investigate thermotolerance development within individual cells. Specifically, we will evaluate: a) compounds that may be physiological """"""""signals"""""""" for thermotolerance development, i.e., glutathione disulfide and phosphorylated dinucleotides; b) total RNA and poly(A)+ RNA from thermotolerance cells; and (c) oncogenes that have been shown to induce the synthesis of heat shock proteins. 3. Glycosylation studies will characterize the incorporation of labeled sugars into cellular proteins during thermotolerance development using SDS-PAGE. Inhibition of thermotolerance development will be measured under conditions that interfere with protein glycosylation and will be compared to thermotolerance inhibition in low-pH medium and stepdown heating. A better understanding of mechanisms of heat prodcuction and thermotolerance, as well as those mechanisms leading to induction or inhibition of thermotolerance development may provide a rational basis for improving clinical applications of hyperthermia in cancer control.
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