CHRONIC THERMOTOLERANCE WITH CONTINUED CELL-PROLIFERATION

The human colon adenocarcinoma cell line, NSY42129, is capable of prol iferation at 41.1 degrees C. This ability appears to be due to a type of chronic thermotolerance, as opposed to selection or adaptation, tha t allows these cells to traverse S phase at elevated temperatures. Fou r other human cell lines were studied for their ability to proliferate at 41.1 degrees C. Of those only one, also a colon adenocarcinoma, sh owed the ability to sustain proliferation at 41.1 degrees C. While all the cell lines examined showed increased levels of the major heat sho ck proteins at 41.1 degrees C, the cellular amounts of these proteins did not correlate with their ability to proliferate at 41.1 degrees C. However, the ability of the cells to proliferate at 41.1 degrees C di d correlate with their ability to sustain elevated rates of synthesis of hsp70 and hsp90. These results could have implications in the clini cal application of hyperthermia, particularly the use of long duration moderate hyperthermia.