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Dichloroacetate, a selective mitochondria-targeting drug for oral squamous cell carcinoma: a metabolic perspective of treatment.

Ruggieri V, Agriesti F, Scrima R, Laurenzana I, Perrone D, Tataranni T, Mazzoccoli C, Lo Muzio L, Capitanio N, Piccoli C - Oncotarget (2015)

Bottom Line: In this study we tested comparatively the effects of DCA on three different OSCC-derived cell lines, HSC-2, HSC-3, PE15.DCA treatment of the three OSCC cell lines, at pharmacological concentrations, resulted in stimulation of the respiratory activity and caused a remarkably distinctive pro-apoptotic/cytostatic effect on HSC-2 and HSC-3.This was accompanied with a large remodeling of the mitochondrial network, never documented before, leading to organelle fragmentation and with enhanced production of reactive oxygen species.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Pre-Clinical and Translational Research, IRCCS, CROB, Rionero in Vulture, Potenza, Italy.

ABSTRACT
Reprogramming of metabolism is a well-established property of cancer cells that is receiving growing attention as potential therapeutic target. Oral squamous cell carcinomas (OSCC) are aggressive and drugs-resistant human tumours displaying wide metabolic heterogeneity depending on their malignant genotype and stage of development. Dichloroacetate (DCA) is a specific inhibitor of the PDH-regulator PDK proved to foster mitochondrial oxidation of pyruvate. In this study we tested comparatively the effects of DCA on three different OSCC-derived cell lines, HSC-2, HSC-3, PE15. Characterization of the three cell lines unveiled for HSC-2 and HSC-3 a glycolysis-reliant metabolism whereas PE15 accomplished an efficient mitochondrial oxidative phosphorylation. DCA treatment of the three OSCC cell lines, at pharmacological concentrations, resulted in stimulation of the respiratory activity and caused a remarkably distinctive pro-apoptotic/cytostatic effect on HSC-2 and HSC-3. This was accompanied with a large remodeling of the mitochondrial network, never documented before, leading to organelle fragmentation and with enhanced production of reactive oxygen species. The data here presented indicate that the therapeutic efficacy of DCA may depend on the specific metabolic profile adopted by the cancer cells with those exhibiting a deficient mitochondrial oxidative phosphorylation resulting more sensitive to the drug treatment.

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Effect of DCA on mitochondrial morpho-functional parametersThe upper panel shows a laser scanning confocal microscopy analysis (LSCM) of the ΔΨm assessed by the fluorescent probe TMRE in live OSCC cells either untreated and incubated with 4 mM DCA for 24 h. An enlarged detail of the optical field (square) is shown aside of each picture and rendered in false colors to highlight the morphology of the mitochondrial network. Imaging is representative of three different experiments yielding comparable results. The graph bars in the bottom panel show the quantitative analysis of ΔΨm-related TMRE fluorescence and of the morphometric parameters, mitochondrial interconnectivity and elongation, calculated as detailed in Materials and Methods. The data reported are means (± SEM) of values referring to at least ten optical fields randomly selected for each condition and clustered from three independent cell preparations. (*) P < 0.05, (**) P < 0.01 vs DCA-untreated.
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Figure 4: Effect of DCA on mitochondrial morpho-functional parametersThe upper panel shows a laser scanning confocal microscopy analysis (LSCM) of the ΔΨm assessed by the fluorescent probe TMRE in live OSCC cells either untreated and incubated with 4 mM DCA for 24 h. An enlarged detail of the optical field (square) is shown aside of each picture and rendered in false colors to highlight the morphology of the mitochondrial network. Imaging is representative of three different experiments yielding comparable results. The graph bars in the bottom panel show the quantitative analysis of ΔΨm-related TMRE fluorescence and of the morphometric parameters, mitochondrial interconnectivity and elongation, calculated as detailed in Materials and Methods. The data reported are means (± SEM) of values referring to at least ten optical fields randomly selected for each condition and clustered from three independent cell preparations. (*) P < 0.05, (**) P < 0.01 vs DCA-untreated.

Mentions: Changes in mitochondrial morphology are emerging as a hallmark for different states of the cell physiology [24]. Using TMRE, we carried out a morpho-functional analysis of the mitochondrial compartment in OSCC cells and the impact on it of DCA (Fig. 4). The results of this analysis showed that the basal level of the ΔΨm-related TMRE fluorescence was comparable among the three OSCC cell lines confirming at the single cell level the observations obtained by flow-cytometry (see Fig. 1C). The morphology of the mitochondrial compartment was characterized by a dense and highly interconnected tubular network with any apparent significant difference among the three OSCC cells lines. Following DCA treatment, the mitochondrial network resulted largely fragmented in HSC-2 cells and, to a lesser extent, in HSC-3 cells but not in PE15 cells. The ΔΨm-related TMRE fluorescence appeared, instead, not significantly affected by DCA treatment in all the OSCC cell samples. Morphometric analysis of the TMRE-related fluorescence signal confirmed in HSC-2 and HSC-3 a significant DCA-mediated decrease of the mitochondrial interconnectivity and elongation.


Dichloroacetate, a selective mitochondria-targeting drug for oral squamous cell carcinoma: a metabolic perspective of treatment.

Ruggieri V, Agriesti F, Scrima R, Laurenzana I, Perrone D, Tataranni T, Mazzoccoli C, Lo Muzio L, Capitanio N, Piccoli C - Oncotarget (2015)

Effect of DCA on mitochondrial morpho-functional parametersThe upper panel shows a laser scanning confocal microscopy analysis (LSCM) of the ΔΨm assessed by the fluorescent probe TMRE in live OSCC cells either untreated and incubated with 4 mM DCA for 24 h. An enlarged detail of the optical field (square) is shown aside of each picture and rendered in false colors to highlight the morphology of the mitochondrial network. Imaging is representative of three different experiments yielding comparable results. The graph bars in the bottom panel show the quantitative analysis of ΔΨm-related TMRE fluorescence and of the morphometric parameters, mitochondrial interconnectivity and elongation, calculated as detailed in Materials and Methods. The data reported are means (± SEM) of values referring to at least ten optical fields randomly selected for each condition and clustered from three independent cell preparations. (*) P < 0.05, (**) P < 0.01 vs DCA-untreated.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359228&req=5

Figure 4: Effect of DCA on mitochondrial morpho-functional parametersThe upper panel shows a laser scanning confocal microscopy analysis (LSCM) of the ΔΨm assessed by the fluorescent probe TMRE in live OSCC cells either untreated and incubated with 4 mM DCA for 24 h. An enlarged detail of the optical field (square) is shown aside of each picture and rendered in false colors to highlight the morphology of the mitochondrial network. Imaging is representative of three different experiments yielding comparable results. The graph bars in the bottom panel show the quantitative analysis of ΔΨm-related TMRE fluorescence and of the morphometric parameters, mitochondrial interconnectivity and elongation, calculated as detailed in Materials and Methods. The data reported are means (± SEM) of values referring to at least ten optical fields randomly selected for each condition and clustered from three independent cell preparations. (*) P < 0.05, (**) P < 0.01 vs DCA-untreated.
Mentions: Changes in mitochondrial morphology are emerging as a hallmark for different states of the cell physiology [24]. Using TMRE, we carried out a morpho-functional analysis of the mitochondrial compartment in OSCC cells and the impact on it of DCA (Fig. 4). The results of this analysis showed that the basal level of the ΔΨm-related TMRE fluorescence was comparable among the three OSCC cell lines confirming at the single cell level the observations obtained by flow-cytometry (see Fig. 1C). The morphology of the mitochondrial compartment was characterized by a dense and highly interconnected tubular network with any apparent significant difference among the three OSCC cells lines. Following DCA treatment, the mitochondrial network resulted largely fragmented in HSC-2 cells and, to a lesser extent, in HSC-3 cells but not in PE15 cells. The ΔΨm-related TMRE fluorescence appeared, instead, not significantly affected by DCA treatment in all the OSCC cell samples. Morphometric analysis of the TMRE-related fluorescence signal confirmed in HSC-2 and HSC-3 a significant DCA-mediated decrease of the mitochondrial interconnectivity and elongation.

Bottom Line: In this study we tested comparatively the effects of DCA on three different OSCC-derived cell lines, HSC-2, HSC-3, PE15.DCA treatment of the three OSCC cell lines, at pharmacological concentrations, resulted in stimulation of the respiratory activity and caused a remarkably distinctive pro-apoptotic/cytostatic effect on HSC-2 and HSC-3.This was accompanied with a large remodeling of the mitochondrial network, never documented before, leading to organelle fragmentation and with enhanced production of reactive oxygen species.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Pre-Clinical and Translational Research, IRCCS, CROB, Rionero in Vulture, Potenza, Italy.

ABSTRACT
Reprogramming of metabolism is a well-established property of cancer cells that is receiving growing attention as potential therapeutic target. Oral squamous cell carcinomas (OSCC) are aggressive and drugs-resistant human tumours displaying wide metabolic heterogeneity depending on their malignant genotype and stage of development. Dichloroacetate (DCA) is a specific inhibitor of the PDH-regulator PDK proved to foster mitochondrial oxidation of pyruvate. In this study we tested comparatively the effects of DCA on three different OSCC-derived cell lines, HSC-2, HSC-3, PE15. Characterization of the three cell lines unveiled for HSC-2 and HSC-3 a glycolysis-reliant metabolism whereas PE15 accomplished an efficient mitochondrial oxidative phosphorylation. DCA treatment of the three OSCC cell lines, at pharmacological concentrations, resulted in stimulation of the respiratory activity and caused a remarkably distinctive pro-apoptotic/cytostatic effect on HSC-2 and HSC-3. This was accompanied with a large remodeling of the mitochondrial network, never documented before, leading to organelle fragmentation and with enhanced production of reactive oxygen species. The data here presented indicate that the therapeutic efficacy of DCA may depend on the specific metabolic profile adopted by the cancer cells with those exhibiting a deficient mitochondrial oxidative phosphorylation resulting more sensitive to the drug treatment.

Show MeSH
Related in: MedlinePlus