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High mitochondrial DNA copy number and bioenergetic function are associated with tumor invasion of esophageal squamous cell carcinoma cell lines.

Lin CS, Lee HT, Lee SY, Shen YA, Wang LS, Chen YJ, Wei YH - Int J Mol Sci (2012)

Bottom Line: Among them, TE1 had the highest relative mtDNA copy number of 240.7%.These findings indicate that TE1 exhibited the highest bioenergetic function of mitochondria.A decline in mitochondrial bioenergetic function was observed in TE1-sh-TFAM(97).

View Article: PubMed Central - PubMed

Affiliation: Institute of Clinical Medicine, National Yang-Ming University, Taipei 112, Taiwan; E-Mails: doc2765c@ms59.hinet.net (C.-S.L.); htlee1228@gmail.com (H.-T.L.); yjchen@ym.edu.tw (Y.-J.C.) ; Faculty of Medicine, National Yang-Ming University, Taipei 112, Taiwan ; Division of Thoracic Surgery, Department of Surgery, Taipei Hospital, Department of Health, Executive Yuan, New Taipei City 242, Taiwan.

ABSTRACT
We previously reported a gradual increase of relative mitochondrial DNA (mtDNA) copy number during the progression of esophageal squamous cell carcinoma (ESCC). Because mitochondria are the intracellular organelles responsible for ATP production, we investigated the associations among mtDNA copy number, mitochondrial bioenergetic function, tumor invasion and the expression levels of epithelial mesenchymal transition (EMT) markers in a series of seven ESCC cell lines, including 48T, 81T, 146T, TE1, TE2, TE6 and TE9. Among them, TE1 had the highest relative mtDNA copy number of 240.7%. The mRNA of mtDNA-encoded ND1 gene (2.80), succinate-supported oxygen consumption rate (11.21 nmol/min/10(6) cells), ATP content (10.7 fmol/cell), and the protein level of mitochondrial transcription factor A (TFAM) were the highest and the lactate concentration in the culture medium (3.34 mM) was the lowest in TE1. These findings indicate that TE1 exhibited the highest bioenergetic function of mitochondria. Furthermore, TE1 showed the highest trans-well migration activity of 223.0 cells/field, the highest vimentin but the lowest E-cadherin protein expression levels, which suggest that TE1 had the highest invasion capability. We then conducted a knockdown study using pLKO.1-based lentiviral particles to infect TE1 cells to suppress the expression of TFAM. Molecular analyses of the parental TE1, control TE1-NT and TFAM knockdown TE1-sh-TFAM(97) cells were performed. Interestingly, as compared to the control TE1-NT, TE1-sh-TFAM(97) exhibited lower levels of the relative mtDNA copy number (p = 0.001), mRNA of mtDNA-encoded ND1 gene (p = 0.050), succinate-supported oxygen consumption rate (p = 0.065), and ATP content (p = 0.007), but had a higher lactate concentration in the culture medium (p = 0.010) and higher protein level of lactate dehydrogenase. A decline in mitochondrial bioenergetic function was observed in TE1-sh-TFAM(97). Significantly, compared to the control TE1-NT, TE1-sh-TFAM(97) had a lower trans-well migration activity (p < 0.001), a higher E-cadherin level but a lower vimentin protein level, which indicates a decrease of invasiveness. Taken together, we suggest that high relative mtDNA copy number and bioenergetic function of mitochondria may confer an advantage for tumor invasion of ESCC.

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Related in: MedlinePlus

Illustration of the quantitative (bar, cells/field) and photographic (light microscopy) results of the assay of trans-well migration activity among the seven cell lines. TE1 exhibited the highest trans-well migration activity.
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f2-ijms-13-11228: Illustration of the quantitative (bar, cells/field) and photographic (light microscopy) results of the assay of trans-well migration activity among the seven cell lines. TE1 exhibited the highest trans-well migration activity.

Mentions: As shown in Table 1 and Figure 2, a significant difference in the trans-well migration activity was noted among the 7 ESCC cell lines, and TE1 exhibited the highest trans-well migration activity of 223 cells/field. Regarding the expression of EMT markers (Figure 1), TE1 had the highest expression levels of vimentin (a mesenchymal cell marker) but the lowest E-cadherin (an epithelial cell marker). Concerning the growth kinetics (Figure 3), TE1 showed the second to the last in the growth rate.


High mitochondrial DNA copy number and bioenergetic function are associated with tumor invasion of esophageal squamous cell carcinoma cell lines.

Lin CS, Lee HT, Lee SY, Shen YA, Wang LS, Chen YJ, Wei YH - Int J Mol Sci (2012)

Illustration of the quantitative (bar, cells/field) and photographic (light microscopy) results of the assay of trans-well migration activity among the seven cell lines. TE1 exhibited the highest trans-well migration activity.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3472741&req=5

f2-ijms-13-11228: Illustration of the quantitative (bar, cells/field) and photographic (light microscopy) results of the assay of trans-well migration activity among the seven cell lines. TE1 exhibited the highest trans-well migration activity.
Mentions: As shown in Table 1 and Figure 2, a significant difference in the trans-well migration activity was noted among the 7 ESCC cell lines, and TE1 exhibited the highest trans-well migration activity of 223 cells/field. Regarding the expression of EMT markers (Figure 1), TE1 had the highest expression levels of vimentin (a mesenchymal cell marker) but the lowest E-cadherin (an epithelial cell marker). Concerning the growth kinetics (Figure 3), TE1 showed the second to the last in the growth rate.

Bottom Line: Among them, TE1 had the highest relative mtDNA copy number of 240.7%.These findings indicate that TE1 exhibited the highest bioenergetic function of mitochondria.A decline in mitochondrial bioenergetic function was observed in TE1-sh-TFAM(97).

View Article: PubMed Central - PubMed

Affiliation: Institute of Clinical Medicine, National Yang-Ming University, Taipei 112, Taiwan; E-Mails: doc2765c@ms59.hinet.net (C.-S.L.); htlee1228@gmail.com (H.-T.L.); yjchen@ym.edu.tw (Y.-J.C.) ; Faculty of Medicine, National Yang-Ming University, Taipei 112, Taiwan ; Division of Thoracic Surgery, Department of Surgery, Taipei Hospital, Department of Health, Executive Yuan, New Taipei City 242, Taiwan.

ABSTRACT
We previously reported a gradual increase of relative mitochondrial DNA (mtDNA) copy number during the progression of esophageal squamous cell carcinoma (ESCC). Because mitochondria are the intracellular organelles responsible for ATP production, we investigated the associations among mtDNA copy number, mitochondrial bioenergetic function, tumor invasion and the expression levels of epithelial mesenchymal transition (EMT) markers in a series of seven ESCC cell lines, including 48T, 81T, 146T, TE1, TE2, TE6 and TE9. Among them, TE1 had the highest relative mtDNA copy number of 240.7%. The mRNA of mtDNA-encoded ND1 gene (2.80), succinate-supported oxygen consumption rate (11.21 nmol/min/10(6) cells), ATP content (10.7 fmol/cell), and the protein level of mitochondrial transcription factor A (TFAM) were the highest and the lactate concentration in the culture medium (3.34 mM) was the lowest in TE1. These findings indicate that TE1 exhibited the highest bioenergetic function of mitochondria. Furthermore, TE1 showed the highest trans-well migration activity of 223.0 cells/field, the highest vimentin but the lowest E-cadherin protein expression levels, which suggest that TE1 had the highest invasion capability. We then conducted a knockdown study using pLKO.1-based lentiviral particles to infect TE1 cells to suppress the expression of TFAM. Molecular analyses of the parental TE1, control TE1-NT and TFAM knockdown TE1-sh-TFAM(97) cells were performed. Interestingly, as compared to the control TE1-NT, TE1-sh-TFAM(97) exhibited lower levels of the relative mtDNA copy number (p = 0.001), mRNA of mtDNA-encoded ND1 gene (p = 0.050), succinate-supported oxygen consumption rate (p = 0.065), and ATP content (p = 0.007), but had a higher lactate concentration in the culture medium (p = 0.010) and higher protein level of lactate dehydrogenase. A decline in mitochondrial bioenergetic function was observed in TE1-sh-TFAM(97). Significantly, compared to the control TE1-NT, TE1-sh-TFAM(97) had a lower trans-well migration activity (p < 0.001), a higher E-cadherin level but a lower vimentin protein level, which indicates a decrease of invasiveness. Taken together, we suggest that high relative mtDNA copy number and bioenergetic function of mitochondria may confer an advantage for tumor invasion of ESCC.

Show MeSH
Related in: MedlinePlus