The effect of temozolomide on Hsp60 and Hsp70 expression in extracellular vesicles derived from U87MG glioma cells

Abstract

Objectives: Temozolomide (TMZ) is an effective drug for glioblastoma multiforme (GBM), but the mechanism underlying TMZ resistance is poorly understood. New evidence has revealed that the release of heat shock proteins (Hsps) derived from extracellular vesicles (EVs) play an important role in cancer progression by modulating tumor microenvironment and cellular cross-talk. This study aims to evaluate the effects of TMZ on the expression of EV-derived and cellular Hsps and cell motility in U87MG human glioblastoma cell line. Methods: Glial-EVs were isolated from the culture medium and characterized by SEM and immunoblotting. The effect of TMZ treatments (25, 200 and 750 µM) on cell proliferation (MTT assay), migration (scratch assay), and Hsp60 and Hsp70 levels (immunoblotting) were evaluated. Results: TMZ treatments led to an increase in intracellular Hsp70 while decreasing EV-derived Hsp70. Cellular Hsp60 level was elevated at the low dose of TMZ, but it reduced at higher TMZ concentrations. Hsp60 was also decreased in EVs secreted from TMZ-treated cells. Besides, TMZ treatment reduced the proliferation and migration of glioma cells in a dose-dependent manner. Conclusions: Our results suggest that TMZ has the potential to target both EV-derived and cellular Hsps for GBM treatment, thus it may reduce cell motility.