Geldanamycin Induces Transactivation of Hsp70a in Human Non-Small Cell Lung Cancer H460 Cells through Calcium Sensitive and Non-Sensitive Pathways

• Main Authors: Nai-Lin Cheng, 鄭乃琳
• Other Authors: Yiu-Kay Lai
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/97390874750001363290

碩士 === 國立清華大學 === 生命科學系 === 89 === The benzoquinoid ansamycin geldanamycin (GA) interferes with many cell-signaling pathways and is currently being evaluated as an anticancer agent. Recent studies have shown that GA induces the expression of heat shock proteins (HSPs), including the HSP70s. The family of 70-kDa heat-shock proteins (HSP70s) is evolutionarily highly conserved and is assumed to serve an important protective function under a variety of adverse envirnmental conditions. In human cells, two stress inducible hsp70 genes, hsp70a and hsp70b, have often been studied. By using metabolic labeling followed by gel electrophoresis, Western and Northern blotting techniques, we found that hsp70a is much more inducible than hsp70b in GA-treated human non-small cell lung cancer H460 cells. The induced expression of HSP70A by GA is dependent on both concentration and the duration. And both actinomycin D and cycloheximide block HSP70A induction. This shows that the effect of GA on HSP70A induction is in transcription level. On the other hand, GA causes intracellular calcium ([Ca2+]i) mobilization, we further analyzed the effect of [Ca2+]i on HSP70A induction in the above processes by exploiting a set of drugs that affect the [Ca2+]i mobilization, including EGTA, BAPTA-AM, A23187, and thapsigargin (TG). It was found that the induced synthesis of HSP70A in GA-treated H460 cells could be attenuated by these drugs, but failed to completely block the HSP70A production and hsp70a mRNA accumulation. Taken together, our results lead us to conclude that GA transactivated hsp70a in H460 cells through calcium-dependent and -independent pathways. ABSTRACT ………………………………………………………………………….3 INTRODUCTION ……………………………………………………………………4 MATERIALS AND METHODS……………………………………………………...7 RESULTS ……………………………………………………………………………12 DISCUSSION ……………………………………………………………………….16 FOOTNOTES ………………………………………………………………………..20 REFFERENCES ……………………………………………………………………..21 FIGURE LEGENDS ………………………………………………………………...28