Evaluation of tellurium toxicity in transformed and non-transformed human colon cells

Di-Ph ditelluride (DPDT)and tellurium tetrachloride (TeCl4) were evaluated for toxicity in transformed (HT-29, Caco-2) and non-transformed colon cells(CCD-18Co). Significant decreases in viability were observed with DPDT exposure in HT-29 (62.5-1000 ?M), Caco-2 (31.25-1000 ?M) and CCD-18Co cells (500-1000 ?M) and with TeCl4 in HT-29 (31.25-1000 ?M), Caco-2 (31.25-1000 ?M) and CCD-18Co cells (500-1000 ?M). Light microscopy confirmed viability analysis. Significant increases in caspase 3/7 and 9 activity were observed with DPDT in HT-29 (500-1000 ?M) and CCD-18Co cells (1000 ?M) indicating apoptosis. No significant increases in caspases were seen with TeCl4 indicating necrosis. Apoptosis or necrosis was confirmed with fluorescent staining (FITC-Annexin, Hoechst 33342 and Ethidium Homodimer). Significant decreases in GSH/GSSG ratio were observed with DPDT in HT-29 (62.5-1000 ?M), and CCD-18Co cells (1000 ?M) and with TeCl4 in HT-29 (62.5-1000 ?M) and CCD-18Co cells (250-1000?M). The authors concluded that cells treated with DPDT resulted in apoptosis and TeCl4 treatment in necrosis. GSH/GSSG ratio shifts indicated that oxidative mechanisms are involved.