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Merkel Cell Polyomavirus Small T Antigen Promotes Pro-Glycolytic Metabolic Perturbations Required for Transformation

View Article: PubMed Central - PubMed

ABSTRACT

Merkel cell polyomavirus (MCPyV) is an etiological agent of Merkel cell carcinoma (MCC), a highly aggressive skin cancer. The MCPyV small tumor antigen (ST) is required for maintenance of MCC and can transform normal cells. To gain insight into cellular perturbations induced by MCPyV ST, we performed transcriptome analysis of normal human fibroblasts with inducible expression of ST. MCPyV ST dynamically alters the cellular transcriptome with increased levels of glycolytic genes, including the monocarboxylate lactate transporter SLC16A1 (MCT1). Extracellular flux analysis revealed increased lactate export reflecting elevated aerobic glycolysis in ST expressing cells. Inhibition of MCT1 activity suppressed the growth of MCC cell lines and impaired MCPyV-dependent transformation of IMR90 cells. Both NF-κB and MYC have been shown to regulate MCT1 expression. While MYC was required for MCT1 induction, MCPyV-induced MCT1 levels decreased following knockdown of the NF-κB subunit RelA, supporting a synergistic activity between MCPyV and MYC in regulating MCT1 levels. Several MCC lines had high levels of MYCL and MYCN but not MYC. Increased levels of MYCL was more effective than MYC or MYCN in increasing extracellular acidification in MCC cells. Our results demonstrate the effects of MCPyV ST on the cellular transcriptome and reveal that transformation is dependent, at least in part, on elevated aerobic glycolysis.

No MeSH data available.


MYC isoforms differentially regulate glycolysis gene expression and ECAR of MCC cells.A) MKL-1 and WaGa cells containing inducible vectors for MYC, MYCN or MYCL were treated with (+) or without (-) dox for 72 hours and lysates were immunoblotted with the indicated antibodies. B) ECAR (mpH/min) of MKL-1 cells inducibly expressing GFP, MYC, MYCN or MYCL after 72 hours of dox addition (minutes). Cells were treated with oligomycin (1 μM) at the indicated time point. *P < 0.05 calculated using unpaired student’s T test between MYC and MYCL samples.
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ppat.1006020.g005: MYC isoforms differentially regulate glycolysis gene expression and ECAR of MCC cells.A) MKL-1 and WaGa cells containing inducible vectors for MYC, MYCN or MYCL were treated with (+) or without (-) dox for 72 hours and lysates were immunoblotted with the indicated antibodies. B) ECAR (mpH/min) of MKL-1 cells inducibly expressing GFP, MYC, MYCN or MYCL after 72 hours of dox addition (minutes). Cells were treated with oligomycin (1 μM) at the indicated time point. *P < 0.05 calculated using unpaired student’s T test between MYC and MYCL samples.

Mentions: We next determined the ability of each MYC family member to regulate glycolytic gene expression and aerobic glycolysis in MCC cell lines. MKL-1 and WaGa cells were transduced with dox inducible vectors expressing MYC, MYCN or MYCL. Following selection, cells were treated with dox for 72 hours, and then lysates were harvested for immunoblotting (Fig 5A). We observed that MYC and MYCN but not MYCL led to increased levels of HK2 and LDHA in MKL-1 and WaGa cells. MYC and MYCL led to increased levels of MCT1 while MYCN led to decreased MCT1 levels in WaGa cells.


Merkel Cell Polyomavirus Small T Antigen Promotes Pro-Glycolytic Metabolic Perturbations Required for Transformation
MYC isoforms differentially regulate glycolysis gene expression and ECAR of MCC cells.A) MKL-1 and WaGa cells containing inducible vectors for MYC, MYCN or MYCL were treated with (+) or without (-) dox for 72 hours and lysates were immunoblotted with the indicated antibodies. B) ECAR (mpH/min) of MKL-1 cells inducibly expressing GFP, MYC, MYCN or MYCL after 72 hours of dox addition (minutes). Cells were treated with oligomycin (1 μM) at the indicated time point. *P < 0.05 calculated using unpaired student’s T test between MYC and MYCL samples.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5120958&req=5

ppat.1006020.g005: MYC isoforms differentially regulate glycolysis gene expression and ECAR of MCC cells.A) MKL-1 and WaGa cells containing inducible vectors for MYC, MYCN or MYCL were treated with (+) or without (-) dox for 72 hours and lysates were immunoblotted with the indicated antibodies. B) ECAR (mpH/min) of MKL-1 cells inducibly expressing GFP, MYC, MYCN or MYCL after 72 hours of dox addition (minutes). Cells were treated with oligomycin (1 μM) at the indicated time point. *P < 0.05 calculated using unpaired student’s T test between MYC and MYCL samples.
Mentions: We next determined the ability of each MYC family member to regulate glycolytic gene expression and aerobic glycolysis in MCC cell lines. MKL-1 and WaGa cells were transduced with dox inducible vectors expressing MYC, MYCN or MYCL. Following selection, cells were treated with dox for 72 hours, and then lysates were harvested for immunoblotting (Fig 5A). We observed that MYC and MYCN but not MYCL led to increased levels of HK2 and LDHA in MKL-1 and WaGa cells. MYC and MYCL led to increased levels of MCT1 while MYCN led to decreased MCT1 levels in WaGa cells.

View Article: PubMed Central - PubMed

ABSTRACT

Merkel cell polyomavirus (MCPyV) is an etiological agent of Merkel cell carcinoma (MCC), a highly aggressive skin cancer. The MCPyV small tumor antigen (ST) is required for maintenance of MCC and can transform normal cells. To gain insight into cellular perturbations induced by MCPyV ST, we performed transcriptome analysis of normal human fibroblasts with inducible expression of ST. MCPyV ST dynamically alters the cellular transcriptome with increased levels of glycolytic genes, including the monocarboxylate lactate transporter SLC16A1 (MCT1). Extracellular flux analysis revealed increased lactate export reflecting elevated aerobic glycolysis in ST expressing cells. Inhibition of MCT1 activity suppressed the growth of MCC cell lines and impaired MCPyV-dependent transformation of IMR90 cells. Both NF-&kappa;B and MYC have been shown to regulate MCT1 expression. While MYC was required for MCT1 induction, MCPyV-induced MCT1 levels decreased following knockdown of the NF-&kappa;B subunit RelA, supporting a synergistic activity between MCPyV and MYC in regulating MCT1 levels. Several MCC lines had high levels of MYCL and MYCN but not MYC. Increased levels of MYCL was more effective than MYC or MYCN in increasing extracellular acidification in MCC cells. Our results demonstrate the effects of MCPyV ST on the cellular transcriptome and reveal that transformation is dependent, at least in part, on elevated aerobic glycolysis.

No MeSH data available.