Mechanism of temozolomide-induced antitumour effects on glioma cells

Abstract

Objective: To investigate the mechanisms of action of the tumoricidal effects of temozolomide against the human glioma cell line U251 in vitro, and to provide preclinical proof-of-concept studies of the effects of temozolomide-containing regimens. Methods: U251 cells were exposed to 100 mmol/l temozolomide. Morphological alterations were monitored by light microscopy. Cell viability was measured using the 3 -(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell cycle analysis and the rate of apoptosis were determined using flow cytometry and the number of acidic vesicular organelles stained with acridine orange were analysed by fluorescence microscopy. The scratch recovery test was used to measure cell migration. Results: U251 cells that were treated with temozolomide displayed morphological alterations indicative of a rounder shape and impaired cellular adhesion to the cell culture plate compared with control U251 cells. Temozolomide reduced cell viability as measured by the MTT assay, caused cell cycle arrest in the gap 2/mitosis phase, inhibited cell migration and promoted autophagy in U251 cells. Conclusion: Temozolomide induced autophagic, but not apoptotic processes, in U251 cells and thus reduced their viability and migration.

Differential expression of miR200a-3p and miR21 in grade II–III and grade IV gliomas

“…S1 and S2). [46][47][48] These results confirm that TMZ is able to affect glioma cell growth by blocking the transit beyond cell cycle phases.…”

“…46,47,49,50 The expression of several genes of interest was measured in a panel of high (GBM) and lower grade gliomas. In parallel, several tumoral cell lines issued from GBM were included in the study.…”

A new epigenetic mechanism of temozolomide action in glioma cells

“…Incubation with TMZ in a concentration range 1 -2000uM up to 48h resulted in a decrease of cell viability up to~16% in HeLa and U118 cells. Our observation is consistent with other reports [30][31][32]. Moreover it has been also shown that TMZ cytotoxicity is not due to induction of apoptosis [31][32].…”

In vitro single-strand DNA damage and cancer cell cytotoxicity effects of Temozolomide

“…TMZ a potent alkylating agent is responsible for induction of autophagy that constitutes degradation of genetic material via formation of autophagosome rather than opting for apoptosis in glioma cells [42][43][44]. During apoptotic DNA fragmentation assay, result does not mark the presence of apoptotic DNA.…”