Enhancement of radiation-induced apoptosis of human lymphoma U937 cells by sanazole

Abstract

Sanazole has been tested clinically as a hypoxic cell radiosensitizer. In this study, we determined whether sanazole enhances the radiation-induced apoptosis of human lymphoma U937 cells. Our results revealed that, compared with 10 mM sanazole or radiation alone, the combination of both resulted in a significant enhancement of apoptosis after 6 h, which was evaluated on the basis of DNA fragmentation, morphological changes, and phosphatidylserine externalization. Sanazole alone enhanced intracellular superoxide and hydrogen peroxide formation, which further increased when the cells were irradiated. Significant enhancement of Fas externalization, loss of mitochondrial membrane potential (MMP), and activation of caspase-3 and caspase-8 were observed after the combined treatment. Moreover, this combination could also enhance Bid activation, reduction of Hsp70 expression level and release of cytochrome c from the mitochondria to the cytosol. An immediate increase in the intracellular Ca(2+) concentration ([Ca(2+)](i)) was observed after the combined treatment. These results suggest that the intracellular superoxide and peroxide generated by sanazole might be involved in the enhancement of radiation-induced apoptosis, and that these effects are associated with modulation of the Fas-mitochondria-caspase-dependent pathway, an increase in [Ca(2+)](i), and a decrease in the Hsp70 expression levels.

Differential cytotoxicity and sonosensitization by sanazole: effect of cell type and acoustic parameters

“…2c-e). On the other hand, U937 cells did not exhibit signs of cell killing after 6 h of incubation, regardless of sanazole concentration, consistent with previous reports [23,24]. Analysis after 24 h of incubation with sanazole revealed that there was a dose-dependent increase in stained cells, particularly in Annexin V?/PI-cells (cells with signs of early apoptosis) (Fig.…”

“…This reflects the fact that the differences between the two types of cancer are inherent and emphasizes the need for understanding the molecular pathways operating in each case in future studies. This work also emphasizes the effectiveness of sanazole under aerobic conditions, either as a single treatment or as a sensitizer with other therapeutic modalities, which is supported by previous studies [23,24,30]. When cells were exposed to US, the resulting cell membrane damage and cellular mechano-transduction were associated with the formation of intracellular ROS as signalling moieties [31,32].…”

“…In conclusion, sanazole has been shown to be an efficient cytotoxic agent, especially for solid tumour cells, and a cell-sensitizer to a number of physical modalities in vitro, where the enhancement seemed to be irrelevant to the oxic state of the tumour [23,24]. Furthermore, the observed enhancement in cell killing following treatment with sanazole and US reflects the fact that this combination employing ultrasound might be a promising strategy in managing cancer even compared to other physical modalities, e.g.…”

Inhibition of checkpoint kinase 1 abrogates G2/M checkpoint activation and promotes apoptosis under heat stress

“…Cells treated with fluorescein isothiocyanate (FITC)-labeled annexin V (AnV) and a PI kit (Immunotech, Marcelle, France) were subjected to flow cytometry using an EpicsXL flow cytometer (Beckman Coulter, Fullerton, CA), as described previously [24][25][26][27]. A total of 10,000 cells per sample were analyzed in a diparametric plot (FL1 for log FITC and FL4 for log PI) to determine the percentages of phosphatidylserine (PS)-externalized AnV?…”

Evaluation of Sanazole Cytotoxicity in Human Drug-Sensitive and MDR Uterine Sarcoma Cells

“…Though the exact active products are not known, yet, the activation process has been attributed to xanthine oxidase and NADPH/cytochrome P450 reductase [15]. As implied, sanazole effect is attributed to its ability to mimic oxygen in being an electron affinic compound stably accommodating a one-electron, thus its efficacy might be more acknowledged in the absence of oxygen (hypoxic conditions), however, we have previously shown that it can be useful under normoxic conditions [16][17][18].…”