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. Author manuscript; available in PMC: 2013 Sep 23.

Published in final edited form as: Mol Cancer Ther. 2010 May 25;9(6):1852–1863. doi: 10.1158/1535-7163.MCT-09-1098

Panels A and B. Effects of MMC on the cell cycle of CHO-WT and CHO-OR cells. Cell cycle analysis was performed 24 h after treatment with MMC by flow cytometry after propidium iodide staining. Panel A. Analysis of cell cycle in CHO-WT and CHO-OR cells following treatment with increasing concentrations of MMC. Panel B. DNA histograms of CHO cells with or without 0.3 μM MMC treatment. One representative experiment is shown. DNA content is presented on a linear scale. Panel C. Comparison of cytochrome P450 reductase activity, MMC-induced redox cycling and cytotoxicity in different tumor cell lines. Left panel. Correlation between cellular cytochrome P450 reductase activity and MMC-induced H₂O₂ production. Cytochrome P450 reductase activity in the cell lines was quantified using a cytochrome c reduction assay and presented in an earlier publication (27). The Vmax for MMC-induced H₂O₂ generation (Table 1) was used to compare MMC-induced redox cycling with cellular cytochrome P450 reductase activity. The insert shows the correlation between cytochrome P450 reductase activity and MMC-induced H₂O₂ production when CHO-OR cells were not included in the analysis. Right panel. Lack of correlation between MMC-induced redox cycling and cellular cytotoxicity. Redox cycling capacity of the cell lines was plotted against the concentration of MMC inhibiting growth by 50% (IC₅₀) in each cell line (Table 1). (● PC-3, ◯ CHO-WT, ▼ HL-60, △ C2, ■ S-180, □ HT-29, ◆ HeLa, ◇ B16, ▲ RAW 264.7, ▽ MLE 15, CHO-OR)

Inline graphic — Panels A and B. Effects of MMC on the cell cycle of CHO-WT and CHO-OR cells. Cell cycle analysis was performed 24 h after treatment with MMC by flow cytometry after propidium iodide staining. Panel A. Analysis of cell cycle in CHO-WT and CHO-OR cells following treatment with increasing concentrations of MMC. Panel B. DNA histograms of CHO cells with or without 0.3 μM MMC treatment. One representative experiment is shown. DNA content is presented on a linear scale. Panel C. Comparison of cytochrome P450 reductase activity, MMC-induced redox cycling and cytotoxicity in different tumor cell lines. Left panel. Correlation between cellular cytochrome P450 reductase activity and MMC-induced H₂O₂ production. Cytochrome P450 reductase activity in the cell lines was quantified using a cytochrome c reduction assay and presented in an earlier publication (27). The Vmax for MMC-induced H₂O₂ generation (Table 1) was used to compare MMC-induced redox cycling with cellular cytochrome P450 reductase activity. The insert shows the correlation between cytochrome P450 reductase activity and MMC-induced H₂O₂ production when CHO-OR cells were not included in the analysis. Right panel. Lack of correlation between MMC-induced redox cycling and cellular cytotoxicity. Redox cycling capacity of the cell lines was plotted against the concentration of MMC inhibiting growth by 50% (IC₅₀) in each cell line (Table 1). (● PC-3, ◯ CHO-WT, ▼ HL-60, △ C2, ■ S-180, □ HT-29, ◆ HeLa, ◇ B16, ▲ RAW 264.7, ▽ MLE 15, CHO-OR)