Reduction of Thermotolerance by Heat Shock Protein 90 Inhibitors in Murine Erythroleukemia Cells.

Reduction of Thermotolerance by Heat Shock Protein 90 Inhibitors in Murine Erythroleukemia Cells. Biol Pharm Bull. 2018;41(9):1393-1400 Authors: Uehara Y, Temma K, Kobayashi Y, Irie N, Yamaguchi T Abstract Cells induce heat shock proteins (HSPs) against various stress. However, murine erythroleukemia (MEL) cells do not express HSP72, a heat-inducible member of HSP70 family. So, it is of interest to examine how MEL cells respond to heat stress (44°C, 30 min). Heat stress-induced apoptosis was suppressed by pretreatment of heat shock (44°C, 10 min). Such suppressive effects were maximal at 6 h after heat shock and remained up to 12 h. Interestingly, such effects of heat shock were abrogated by specific inhibitors of HSP90 such as 17-allylamino-17-demethoxygeldanamycin (17-AAG) and novobiocin. From flow cytometric analysis, it was found that MEL cells arrest in G2 phase at 6 h after heat shock, but restore original cell cycle at 12 h. High expression level of HSP90 was maintained before and after heat shock. Phosphorylation of HSP90α was observed in apoptotic cells induced by heat stress, but inhibited by pretreatment of heat shock. Such inhibition was abrogated by 17-AAG. Moreover, c-Jun NH2-terminal kinase (JNK) was activated in heat stress-induced apoptotic cells. Taken together, these results suggest that HSP90α in MEL cells plays an important role in the thermotolerance, i.e., suppression of heat stress-induced apop...
Source: Biological and Pharmaceutical Bulletin - Category: Drugs & Pharmacology Authors: Tags: Biol Pharm Bull Source Type: research