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Disruption of BASIGIN decreases lactic acid export and sensitizes non-small cell lung cancer to biguanides independently of the LKB1 status.

Granja S, Marchiq I, Le Floch R, Moura CS, Baltazar F, Pouysségur J - Oncotarget (2015)

Bottom Line: The three homozygous BSG-/- cell lines displayed a low MCT activity (10- to 5-fold reduction, for MCT1 and MCT4, respectively) compared to wild-type cells.Consequently, the rate of glycolysis, compared to the wild-type counterpart, was reduced by 2.0- to 3.5-fold, whereas the rate of respiration was stimulated in BSG-/- cell lines.Our results demonstrate that inhibiting glycolysis by targeting lactic acid export sensitizes NSCLC to phenformin.

View Article: PubMed Central - PubMed

Affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal.

ABSTRACT
Most cancers rely on aerobic glycolysis to generate energy and metabolic intermediates. To maintain a high glycolytic rate, cells must efficiently export lactic acid through the proton-coupled monocarboxylate transporters (MCT1/4). These transporters require a chaperone, CD147/BASIGIN (BSG) for trafficking to the plasma membrane and function.To validate the key role of these transporters in lung cancer, we first analysed the expression of MCT1/4 and BSG in 50 non-small lung cancer (NSCLC) cases. These proteins were specifically upregulated in tumour tissues. We then disrupted BSG in three NSCLC cell lines (A549, H1975 and H292) via 'Zinc-Finger Nucleases'. The three homozygous BSG-/- cell lines displayed a low MCT activity (10- to 5-fold reduction, for MCT1 and MCT4, respectively) compared to wild-type cells. Consequently, the rate of glycolysis, compared to the wild-type counterpart, was reduced by 2.0- to 3.5-fold, whereas the rate of respiration was stimulated in BSG-/- cell lines. Both wild-type and BSG- cells were extremely sensitive to the mitochondria inhibitor metformin/phenformin in normoxia. However, only BSG- cells, independently of their LKB1 status, remained sensitive to biguanides in hypoxia in vitro and tumour growth in nude mice. Our results demonstrate that inhibiting glycolysis by targeting lactic acid export sensitizes NSCLC to phenformin.

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Disruption of BSG sensitizes lung carcinoma cells to phenformin in both normoxia and hypoxiaA: Clonal growth of wt and BSG−/− A549 cells in the presence or absence of iMCT1/2 (300nM), metformin (Metf.-1mM), phenformin (Phenf. -50μM) or in combination. Cells were maintained in normoxia for 10 days (upper panel) and in hypoxia (1% O2) for 15 days (lower panel); B: Clonal growth of wt and BSG−/− H1975cells in the presence or absence of iMCT1/2 (300nM), Phenformin (Phenf. -50μM) or in combination iMCT1/2. Cells were maintained in normoxia for 10 days (upper panel) and in hypoxia (1% O2) for 12 days (lower panel).
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Figure 6: Disruption of BSG sensitizes lung carcinoma cells to phenformin in both normoxia and hypoxiaA: Clonal growth of wt and BSG−/− A549 cells in the presence or absence of iMCT1/2 (300nM), metformin (Metf.-1mM), phenformin (Phenf. -50μM) or in combination. Cells were maintained in normoxia for 10 days (upper panel) and in hypoxia (1% O2) for 15 days (lower panel); B: Clonal growth of wt and BSG−/− H1975cells in the presence or absence of iMCT1/2 (300nM), Phenformin (Phenf. -50μM) or in combination iMCT1/2. Cells were maintained in normoxia for 10 days (upper panel) and in hypoxia (1% O2) for 12 days (lower panel).

Mentions: Deletion of BSG did not affect in vitro clonal growth of either A549 or H1975 cells, even in the presence of iMCT1/2 (Fig. 6A, B). However, only wt A549 cells displayed an extremely high sensitivity to metformin/phenformin or oligomycin (not shown), while the more glycolytic H1975 cells remain insensitive (Fig. 6B). This is in agreement with the high oxidative/low glycolytic activity of A549 cells and perhaps also with the loss of LKB1 (see discussion) (Fig. 6A). However, in hypoxia, parental A549 cells lost sensitivity to OXPHOS inhibitors, which is consistent with optimal induction of glycolytic enzymes through stabilization of the hypoxia-inducible factor (HIF). In sharp contrast to wt cells, BSG- cells A549 and H1975 retained a high level of sensitivity to phenformin/metformin alone or in combination with iMCT1/2 (Fig. 6A, B). This striking difference between wt and BSG- cells in hypoxia could easily be explained by the failure of BSG−/− cells to express sufficient hypoxia-inducible MCT4 to sustain glycolysis (Figs. 3A, 4A).


Disruption of BASIGIN decreases lactic acid export and sensitizes non-small cell lung cancer to biguanides independently of the LKB1 status.

Granja S, Marchiq I, Le Floch R, Moura CS, Baltazar F, Pouysségur J - Oncotarget (2015)

Disruption of BSG sensitizes lung carcinoma cells to phenformin in both normoxia and hypoxiaA: Clonal growth of wt and BSG−/− A549 cells in the presence or absence of iMCT1/2 (300nM), metformin (Metf.-1mM), phenformin (Phenf. -50μM) or in combination. Cells were maintained in normoxia for 10 days (upper panel) and in hypoxia (1% O2) for 15 days (lower panel); B: Clonal growth of wt and BSG−/− H1975cells in the presence or absence of iMCT1/2 (300nM), Phenformin (Phenf. -50μM) or in combination iMCT1/2. Cells were maintained in normoxia for 10 days (upper panel) and in hypoxia (1% O2) for 12 days (lower panel).
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Related In: Results  -  Collection

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Figure 6: Disruption of BSG sensitizes lung carcinoma cells to phenformin in both normoxia and hypoxiaA: Clonal growth of wt and BSG−/− A549 cells in the presence or absence of iMCT1/2 (300nM), metformin (Metf.-1mM), phenformin (Phenf. -50μM) or in combination. Cells were maintained in normoxia for 10 days (upper panel) and in hypoxia (1% O2) for 15 days (lower panel); B: Clonal growth of wt and BSG−/− H1975cells in the presence or absence of iMCT1/2 (300nM), Phenformin (Phenf. -50μM) or in combination iMCT1/2. Cells were maintained in normoxia for 10 days (upper panel) and in hypoxia (1% O2) for 12 days (lower panel).
Mentions: Deletion of BSG did not affect in vitro clonal growth of either A549 or H1975 cells, even in the presence of iMCT1/2 (Fig. 6A, B). However, only wt A549 cells displayed an extremely high sensitivity to metformin/phenformin or oligomycin (not shown), while the more glycolytic H1975 cells remain insensitive (Fig. 6B). This is in agreement with the high oxidative/low glycolytic activity of A549 cells and perhaps also with the loss of LKB1 (see discussion) (Fig. 6A). However, in hypoxia, parental A549 cells lost sensitivity to OXPHOS inhibitors, which is consistent with optimal induction of glycolytic enzymes through stabilization of the hypoxia-inducible factor (HIF). In sharp contrast to wt cells, BSG- cells A549 and H1975 retained a high level of sensitivity to phenformin/metformin alone or in combination with iMCT1/2 (Fig. 6A, B). This striking difference between wt and BSG- cells in hypoxia could easily be explained by the failure of BSG−/− cells to express sufficient hypoxia-inducible MCT4 to sustain glycolysis (Figs. 3A, 4A).

Bottom Line: The three homozygous BSG-/- cell lines displayed a low MCT activity (10- to 5-fold reduction, for MCT1 and MCT4, respectively) compared to wild-type cells.Consequently, the rate of glycolysis, compared to the wild-type counterpart, was reduced by 2.0- to 3.5-fold, whereas the rate of respiration was stimulated in BSG-/- cell lines.Our results demonstrate that inhibiting glycolysis by targeting lactic acid export sensitizes NSCLC to phenformin.

View Article: PubMed Central - PubMed

Affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal.

ABSTRACT
Most cancers rely on aerobic glycolysis to generate energy and metabolic intermediates. To maintain a high glycolytic rate, cells must efficiently export lactic acid through the proton-coupled monocarboxylate transporters (MCT1/4). These transporters require a chaperone, CD147/BASIGIN (BSG) for trafficking to the plasma membrane and function.To validate the key role of these transporters in lung cancer, we first analysed the expression of MCT1/4 and BSG in 50 non-small lung cancer (NSCLC) cases. These proteins were specifically upregulated in tumour tissues. We then disrupted BSG in three NSCLC cell lines (A549, H1975 and H292) via 'Zinc-Finger Nucleases'. The three homozygous BSG-/- cell lines displayed a low MCT activity (10- to 5-fold reduction, for MCT1 and MCT4, respectively) compared to wild-type cells. Consequently, the rate of glycolysis, compared to the wild-type counterpart, was reduced by 2.0- to 3.5-fold, whereas the rate of respiration was stimulated in BSG-/- cell lines. Both wild-type and BSG- cells were extremely sensitive to the mitochondria inhibitor metformin/phenformin in normoxia. However, only BSG- cells, independently of their LKB1 status, remained sensitive to biguanides in hypoxia in vitro and tumour growth in nude mice. Our results demonstrate that inhibiting glycolysis by targeting lactic acid export sensitizes NSCLC to phenformin.

Show MeSH
Related in: MedlinePlus