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c-MYC responds to glucose deprivation in a cell-type-dependent manner

View Article: PubMed Central - PubMed

ABSTRACT

Metabolic reprogramming supports cancer cells’ demands for rapid proliferation and growth. Previous work shows that oncogenes, such as MYC, hypoxia-inducible factor 1 (HIF1), have a central role in driving metabolic reprogramming. A lot of metabolic enzymes, which are deregulated in most cancer cells, are the targets of these oncogenes. However, whether metabolic change affects these oncogenes is still unclear. Here we show that glucose deprivation (GD) affects c-MYC protein levels in a cell-type-dependent manner regardless of P53 mutation status. GD dephosphorylates and then decreases c-MYC protein stability through PI3K signaling pathway in HeLa cells, but not in MDA-MB-231 cells. Role of c-MYC in sensitivity of GD also varies with cell types. c-MYC-mediated glutamine metabolism partially improves the sensitivity of GD in MDA-MB-231 cells. Our results reveal that the heterogeneity of cancer cells in response to metabolic stress should be considered in metabolic therapy for cancer.

No MeSH data available.


Glucose deprivation increases c-MYC transcription partially through ERK signaling pathway in MDA-MB-231 cells. Quantitative RT-PCR (a) and Western blot (b and c) detection of c-MYC in MDA-MB-231 cells treated with different chemical inhibitors for 12 h in the medium with or without glucose. The indicated chemical inhibitors are AMPK inhibitor P5499 (10 μM), p38/MAPK inhibitor SB 203580 (10 μM), PI3K/AKT inhibitor Wortmannin (10 μM), ERK/MEK inhibitor U0126 (10 μM), SIRT inhibitor NAM (1 mM) and HDAC inhibitor VPA (1 mM). (d–f) HeLa cells were treated and detected as that of MDA-MB-231 in a–c. Quantitative RT-PCR values were relative to the DMSO group with 25 mM Glc and normalized to 18S. Data of three independent experiments are shown.
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fig4: Glucose deprivation increases c-MYC transcription partially through ERK signaling pathway in MDA-MB-231 cells. Quantitative RT-PCR (a) and Western blot (b and c) detection of c-MYC in MDA-MB-231 cells treated with different chemical inhibitors for 12 h in the medium with or without glucose. The indicated chemical inhibitors are AMPK inhibitor P5499 (10 μM), p38/MAPK inhibitor SB 203580 (10 μM), PI3K/AKT inhibitor Wortmannin (10 μM), ERK/MEK inhibitor U0126 (10 μM), SIRT inhibitor NAM (1 mM) and HDAC inhibitor VPA (1 mM). (d–f) HeLa cells were treated and detected as that of MDA-MB-231 in a–c. Quantitative RT-PCR values were relative to the DMSO group with 25 mM Glc and normalized to 18S. Data of three independent experiments are shown.

Mentions: Figures 1d and e showed that c-MYC transcription was elevated in both HeLa and MDA-MB-231 cells. Given that GD affects several signaling pathways such as p38/MAPK,49 PI3K/AKT,50 ERK51 and AMPK,52 chemical inhibitors were applied to examine which pathway is involved in GD-mediated elevation of c-MYC transcription. Phosphorylation specific antibodies p-p38, p-AKT, p-ERK and p-ACC were used as indicators to show the effects of the inhibitors. We observed that p38/MAPK, PI3K/AKT, ERK and AMPK pathways were all activated after GD and only ERK inhibitor U0126 blocked both mRNA and protein levels in HeLa and MDA-MB-231 cells whether glucose existed or not (Figure 4). However, c-MYC mRNA and protein levels were still elevated in MDA-MB-231 cells and reduced in HeLa cells after GD when ERK signaling was inhibited by U0126. These data indicate that ERK pathway is partially involved in GD-mediated c-MYC transcription activation in both HeLa and MDA-MB-231 cells.


c-MYC responds to glucose deprivation in a cell-type-dependent manner
Glucose deprivation increases c-MYC transcription partially through ERK signaling pathway in MDA-MB-231 cells. Quantitative RT-PCR (a) and Western blot (b and c) detection of c-MYC in MDA-MB-231 cells treated with different chemical inhibitors for 12 h in the medium with or without glucose. The indicated chemical inhibitors are AMPK inhibitor P5499 (10 μM), p38/MAPK inhibitor SB 203580 (10 μM), PI3K/AKT inhibitor Wortmannin (10 μM), ERK/MEK inhibitor U0126 (10 μM), SIRT inhibitor NAM (1 mM) and HDAC inhibitor VPA (1 mM). (d–f) HeLa cells were treated and detected as that of MDA-MB-231 in a–c. Quantitative RT-PCR values were relative to the DMSO group with 25 mM Glc and normalized to 18S. Data of three independent experiments are shown.
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Related In: Results  -  Collection

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fig4: Glucose deprivation increases c-MYC transcription partially through ERK signaling pathway in MDA-MB-231 cells. Quantitative RT-PCR (a) and Western blot (b and c) detection of c-MYC in MDA-MB-231 cells treated with different chemical inhibitors for 12 h in the medium with or without glucose. The indicated chemical inhibitors are AMPK inhibitor P5499 (10 μM), p38/MAPK inhibitor SB 203580 (10 μM), PI3K/AKT inhibitor Wortmannin (10 μM), ERK/MEK inhibitor U0126 (10 μM), SIRT inhibitor NAM (1 mM) and HDAC inhibitor VPA (1 mM). (d–f) HeLa cells were treated and detected as that of MDA-MB-231 in a–c. Quantitative RT-PCR values were relative to the DMSO group with 25 mM Glc and normalized to 18S. Data of three independent experiments are shown.
Mentions: Figures 1d and e showed that c-MYC transcription was elevated in both HeLa and MDA-MB-231 cells. Given that GD affects several signaling pathways such as p38/MAPK,49 PI3K/AKT,50 ERK51 and AMPK,52 chemical inhibitors were applied to examine which pathway is involved in GD-mediated elevation of c-MYC transcription. Phosphorylation specific antibodies p-p38, p-AKT, p-ERK and p-ACC were used as indicators to show the effects of the inhibitors. We observed that p38/MAPK, PI3K/AKT, ERK and AMPK pathways were all activated after GD and only ERK inhibitor U0126 blocked both mRNA and protein levels in HeLa and MDA-MB-231 cells whether glucose existed or not (Figure 4). However, c-MYC mRNA and protein levels were still elevated in MDA-MB-231 cells and reduced in HeLa cells after GD when ERK signaling was inhibited by U0126. These data indicate that ERK pathway is partially involved in GD-mediated c-MYC transcription activation in both HeLa and MDA-MB-231 cells.

View Article: PubMed Central - PubMed

ABSTRACT

Metabolic reprogramming supports cancer cells’ demands for rapid proliferation and growth. Previous work shows that oncogenes, such as MYC, hypoxia-inducible factor 1 (HIF1), have a central role in driving metabolic reprogramming. A lot of metabolic enzymes, which are deregulated in most cancer cells, are the targets of these oncogenes. However, whether metabolic change affects these oncogenes is still unclear. Here we show that glucose deprivation (GD) affects c-MYC protein levels in a cell-type-dependent manner regardless of P53 mutation status. GD dephosphorylates and then decreases c-MYC protein stability through PI3K signaling pathway in HeLa cells, but not in MDA-MB-231 cells. Role of c-MYC in sensitivity of GD also varies with cell types. c-MYC-mediated glutamine metabolism partially improves the sensitivity of GD in MDA-MB-231 cells. Our results reveal that the heterogeneity of cancer cells in response to metabolic stress should be considered in metabolic therapy for cancer.

No MeSH data available.