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Mitochondria-targeted vitamin E analogs inhibit breast cancer cell energy metabolism and promote cell death.

Cheng G, Zielonka J, McAllister DM, Mackinnon AC, Joseph J, Dwinell MB, Kalyanaraman B - BMC Cancer (2013)

Bottom Line: Recent research has revealed that targeting mitochondrial bioenergetic metabolism is a promising chemotherapeutic strategy.Assays of cell death, colony formation, mitochondrial bioenergetic function, intracellular ATP levels, intracellular and tissue concentrations of tested compounds, and in vivo tumor growth were performed.These effects were significantly augmented by inhibition of glycolysis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Free Radical Research Center and Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA.

ABSTRACT

Background: Recent research has revealed that targeting mitochondrial bioenergetic metabolism is a promising chemotherapeutic strategy. Key to successful implementation of this chemotherapeutic strategy is the use of new and improved mitochondria-targeted cationic agents that selectively inhibit energy metabolism in breast cancer cells, while exerting little or no long-term cytotoxic effect in normal cells.

Methods: In this study, we investigated the cytotoxicity and alterations in bioenergetic metabolism induced by mitochondria-targeted vitamin E analog (Mito-chromanol, Mito-ChM) and its acetylated ester analog (Mito-ChMAc). Assays of cell death, colony formation, mitochondrial bioenergetic function, intracellular ATP levels, intracellular and tissue concentrations of tested compounds, and in vivo tumor growth were performed.

Results: Both Mito-ChM and Mito-ChMAc selectively depleted intracellular ATP and caused prolonged inhibition of ATP-linked oxygen consumption rate in breast cancer cells, but not in non-cancerous cells. These effects were significantly augmented by inhibition of glycolysis. Mito-ChM and Mito-ChMAc exhibited anti-proliferative effects and cytotoxicity in several breast cancer cells with different genetic background. Furthermore, Mito-ChM selectively accumulated in tumor tissue and inhibited tumor growth in a xenograft model of human breast cancer.

Conclusions: We conclude that mitochondria-targeted small molecular weight chromanols exhibit selective anti-proliferative effects and cytotoxicity in multiple breast cancer cells, and that esterification of the hydroxyl group in mito-chromanols is not a critical requirement for its anti-proliferative and cytotoxic effect.

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The cytotoxic effect of Mito-ChM in breast cancer and non-cancerous cells. Nine different breast cancer cells and MCF-10A cells were treated with Mito-ChM at the indicated concentrations (0.5-20 μM) for 24 h, and cell death was monitored in real time by Sytox Green staining. Data shown are the means ± SEM for n = 4. Real time cell death curves were plotted in panel A for MCF-7 (left), MDA-MB-231 (middle) and MCF-10A cells (right). Panel B shows the titration of breast cancer and non-cancerous cells with Mito-ChM, and the extent of cell death observed after 4 h treatment is plotted against Mito-ChM concentration. Solid lines represent the fitting curves used for determination of the EC50 values, indicated in each panel.
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Figure 1: The cytotoxic effect of Mito-ChM in breast cancer and non-cancerous cells. Nine different breast cancer cells and MCF-10A cells were treated with Mito-ChM at the indicated concentrations (0.5-20 μM) for 24 h, and cell death was monitored in real time by Sytox Green staining. Data shown are the means ± SEM for n = 4. Real time cell death curves were plotted in panel A for MCF-7 (left), MDA-MB-231 (middle) and MCF-10A cells (right). Panel B shows the titration of breast cancer and non-cancerous cells with Mito-ChM, and the extent of cell death observed after 4 h treatment is plotted against Mito-ChM concentration. Solid lines represent the fitting curves used for determination of the EC50 values, indicated in each panel.

Mentions: The dose-dependent cytotoxicity of Mito-ChM or Mito-ChMAc in nine breast cancer and non-cancerous MCF-10A cells was monitored for 24 h (Figure 1). Both Mito-ChM and Mito-ChMAc caused a dramatic increase in cytotoxicity in all nine breast cancer cell lines tested (Figure 1 and Additional file 1: Figure S2) but not in MCF-10A cells (Figure 1A and Additional file 1: Figure S2). The EC50 values (concentration inducing 50% of cell death) for Mito-ChM after a 4 h treatment in all cell lines tested are shown in Figure 1B. In eight out of nine breast cancer cell lines, the EC50 values measured for Mito-ChM were below 10 μM. The acetate ester of Mito-ChM exhibited similar but slightly higher EC50 values, as shown in Additional file 1: Figure S2B. With MCF-7 cells, the estimated EC50 for Mito-ChM at 4 h was 20 μM, while in MCF-10A we did not observe any toxicity under these conditions. The relatively higher EC50 value in MCF-7 cells can be ra tionalized by a delayed response to Mito-ChM, as shown in Figure 1A. Notably, the EC50 values of Mito-ChM in MCF-7 cells measured to be ca. 10.4 ± 0.2 μM and 7.8 ± 0.4 μM for a 12 and 24 h incubation period, respectively. The EC50 values for Mito-ChMAc under the same conditions were 11.9 ± 0.4 μM (12 h) and 8.8 ± 0.1 μM (24 h) (Additional file 1: Figure S2). In contrast, the EC50 values for these agents in MCF-10A cells were much greater than 20 μM (Figure 1A and Additional file 1: Figure S2) even after a 24 h incubation.


Mitochondria-targeted vitamin E analogs inhibit breast cancer cell energy metabolism and promote cell death.

Cheng G, Zielonka J, McAllister DM, Mackinnon AC, Joseph J, Dwinell MB, Kalyanaraman B - BMC Cancer (2013)

The cytotoxic effect of Mito-ChM in breast cancer and non-cancerous cells. Nine different breast cancer cells and MCF-10A cells were treated with Mito-ChM at the indicated concentrations (0.5-20 μM) for 24 h, and cell death was monitored in real time by Sytox Green staining. Data shown are the means ± SEM for n = 4. Real time cell death curves were plotted in panel A for MCF-7 (left), MDA-MB-231 (middle) and MCF-10A cells (right). Panel B shows the titration of breast cancer and non-cancerous cells with Mito-ChM, and the extent of cell death observed after 4 h treatment is plotted against Mito-ChM concentration. Solid lines represent the fitting curves used for determination of the EC50 values, indicated in each panel.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3686663&req=5

Figure 1: The cytotoxic effect of Mito-ChM in breast cancer and non-cancerous cells. Nine different breast cancer cells and MCF-10A cells were treated with Mito-ChM at the indicated concentrations (0.5-20 μM) for 24 h, and cell death was monitored in real time by Sytox Green staining. Data shown are the means ± SEM for n = 4. Real time cell death curves were plotted in panel A for MCF-7 (left), MDA-MB-231 (middle) and MCF-10A cells (right). Panel B shows the titration of breast cancer and non-cancerous cells with Mito-ChM, and the extent of cell death observed after 4 h treatment is plotted against Mito-ChM concentration. Solid lines represent the fitting curves used for determination of the EC50 values, indicated in each panel.
Mentions: The dose-dependent cytotoxicity of Mito-ChM or Mito-ChMAc in nine breast cancer and non-cancerous MCF-10A cells was monitored for 24 h (Figure 1). Both Mito-ChM and Mito-ChMAc caused a dramatic increase in cytotoxicity in all nine breast cancer cell lines tested (Figure 1 and Additional file 1: Figure S2) but not in MCF-10A cells (Figure 1A and Additional file 1: Figure S2). The EC50 values (concentration inducing 50% of cell death) for Mito-ChM after a 4 h treatment in all cell lines tested are shown in Figure 1B. In eight out of nine breast cancer cell lines, the EC50 values measured for Mito-ChM were below 10 μM. The acetate ester of Mito-ChM exhibited similar but slightly higher EC50 values, as shown in Additional file 1: Figure S2B. With MCF-7 cells, the estimated EC50 for Mito-ChM at 4 h was 20 μM, while in MCF-10A we did not observe any toxicity under these conditions. The relatively higher EC50 value in MCF-7 cells can be ra tionalized by a delayed response to Mito-ChM, as shown in Figure 1A. Notably, the EC50 values of Mito-ChM in MCF-7 cells measured to be ca. 10.4 ± 0.2 μM and 7.8 ± 0.4 μM for a 12 and 24 h incubation period, respectively. The EC50 values for Mito-ChMAc under the same conditions were 11.9 ± 0.4 μM (12 h) and 8.8 ± 0.1 μM (24 h) (Additional file 1: Figure S2). In contrast, the EC50 values for these agents in MCF-10A cells were much greater than 20 μM (Figure 1A and Additional file 1: Figure S2) even after a 24 h incubation.

Bottom Line: Recent research has revealed that targeting mitochondrial bioenergetic metabolism is a promising chemotherapeutic strategy.Assays of cell death, colony formation, mitochondrial bioenergetic function, intracellular ATP levels, intracellular and tissue concentrations of tested compounds, and in vivo tumor growth were performed.These effects were significantly augmented by inhibition of glycolysis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Free Radical Research Center and Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA.

ABSTRACT

Background: Recent research has revealed that targeting mitochondrial bioenergetic metabolism is a promising chemotherapeutic strategy. Key to successful implementation of this chemotherapeutic strategy is the use of new and improved mitochondria-targeted cationic agents that selectively inhibit energy metabolism in breast cancer cells, while exerting little or no long-term cytotoxic effect in normal cells.

Methods: In this study, we investigated the cytotoxicity and alterations in bioenergetic metabolism induced by mitochondria-targeted vitamin E analog (Mito-chromanol, Mito-ChM) and its acetylated ester analog (Mito-ChMAc). Assays of cell death, colony formation, mitochondrial bioenergetic function, intracellular ATP levels, intracellular and tissue concentrations of tested compounds, and in vivo tumor growth were performed.

Results: Both Mito-ChM and Mito-ChMAc selectively depleted intracellular ATP and caused prolonged inhibition of ATP-linked oxygen consumption rate in breast cancer cells, but not in non-cancerous cells. These effects were significantly augmented by inhibition of glycolysis. Mito-ChM and Mito-ChMAc exhibited anti-proliferative effects and cytotoxicity in several breast cancer cells with different genetic background. Furthermore, Mito-ChM selectively accumulated in tumor tissue and inhibited tumor growth in a xenograft model of human breast cancer.

Conclusions: We conclude that mitochondria-targeted small molecular weight chromanols exhibit selective anti-proliferative effects and cytotoxicity in multiple breast cancer cells, and that esterification of the hydroxyl group in mito-chromanols is not a critical requirement for its anti-proliferative and cytotoxic effect.

Show MeSH
Related in: MedlinePlus