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AMPK maintains energy homeostasis and survival in cancer cells via regulating p38/PGC-1 α -mediated mitochondrial biogenesis

View Article: PubMed Central - PubMed

ABSTRACT

Cancer cells exhibit unique metabolic response and adaptation to the fluctuating microenvironment, yet molecular and biochemical events imprinting this phenomenon are unclear. Here, we show that metabolic homeostasis and adaptation to metabolic stress in cancer cells are primarily achieved by an integrated response exerted by the activation of AMPK. We provide evidence that AMPK-p38-PGC-1α axis, by regulating energy homeostasis, maintains survival in cancer cells under glucose-limiting conditions. Functioning as a molecular switch, AMPK promotes glycolysis by activating PFK2, and facilitates mitochondrial metabolism of non-glucose carbon sources thereby maintaining cellular ATP level. Interestingly, we noted that AMPK can promote oxidative metabolism via increasing mitochondrial biogenesis and OXPHOS capacity via regulating expression of PGC-1α through p38MAPK activation. Taken together, our study signifies the fundamental role of AMPK in controlling cellular bioenergetics and mitochondrial biogenesis in cancer cells.

No MeSH data available.


Related in: MedlinePlus

AMPK controls metabolic homeostasis in cancer cells. (a) WT and DKO MEFs were cultured in DMEM containing either 25 or 1 mM glucose and 2 mM glutamine for 24 h. The medium was replaced with fresh medium containing 25 mM glucose and further grown for 24 h. Size of these cells were determined by flow cytometry. Relative size of WT and AMPK-DKO cells under normal metabolic condition (25 mM glucose) (i), change in cell size of WT-MEF (ii) and DKO-MEF (iii), cultured in the presence of 25 mM glucose, 1 mM glucose or re-fed with 25 mM glucose. (b) Mitochondrial membrane potential (MMP) in MEF cells grown under the conditions mentioned in a. DiOC6 was used to determine MMP by flow cytometry. (c) MEF and cancer cells (H1299-DN and MCF7-DN) were grown under the conditions mentioned above. Mitochondrial density was determined by flow cytometry using probe MitoTracker Red FM. Mitochondrial density in WT (i), AMPK-DKO MEFs (ii), H1299 (EV and DN) (iii) and MCF7 (EV and DN) cells (iv). (d–f) MEFs (WT and DKO), H1299 (EV and DN) cells were cultured under the indicated conditions for 24 h. Citrate synthase activity (d and f) and relative ATP levels (e and g) were determined in these cells as described in Materials and Methods. Values are represented as mean±S.D. *P<0.05 and **P<0.01 denote significant differences between the groups.
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fig4: AMPK controls metabolic homeostasis in cancer cells. (a) WT and DKO MEFs were cultured in DMEM containing either 25 or 1 mM glucose and 2 mM glutamine for 24 h. The medium was replaced with fresh medium containing 25 mM glucose and further grown for 24 h. Size of these cells were determined by flow cytometry. Relative size of WT and AMPK-DKO cells under normal metabolic condition (25 mM glucose) (i), change in cell size of WT-MEF (ii) and DKO-MEF (iii), cultured in the presence of 25 mM glucose, 1 mM glucose or re-fed with 25 mM glucose. (b) Mitochondrial membrane potential (MMP) in MEF cells grown under the conditions mentioned in a. DiOC6 was used to determine MMP by flow cytometry. (c) MEF and cancer cells (H1299-DN and MCF7-DN) were grown under the conditions mentioned above. Mitochondrial density was determined by flow cytometry using probe MitoTracker Red FM. Mitochondrial density in WT (i), AMPK-DKO MEFs (ii), H1299 (EV and DN) (iii) and MCF7 (EV and DN) cells (iv). (d–f) MEFs (WT and DKO), H1299 (EV and DN) cells were cultured under the indicated conditions for 24 h. Citrate synthase activity (d and f) and relative ATP levels (e and g) were determined in these cells as described in Materials and Methods. Values are represented as mean±S.D. *P<0.05 and **P<0.01 denote significant differences between the groups.

Mentions: To explore whether AMPK is involved in maintaining metabolic and energy homeostasis, we cultured MEF cells in 25 or 1 mM glucose for 24 h, and these were replenished with 25 mM glucose thereafter. We noticed that AMPK-DKO cells are larger in size as compared with WT cells cultured in 25 mM glucose (Figure 4a-i). An increase in the cell size of WT-MEF was observed upon switching them to 1 mM glucose, while replenishing glucose-restored cell size (Figure 4a-ii). On the other hand, cell size did not alter in DKO cells under identical conditions (Figure 4a-iii). This observation suggests the involvement of AMPK in regulating cell size under metabolic stress.


AMPK maintains energy homeostasis and survival in cancer cells via regulating p38/PGC-1 α -mediated mitochondrial biogenesis
AMPK controls metabolic homeostasis in cancer cells. (a) WT and DKO MEFs were cultured in DMEM containing either 25 or 1 mM glucose and 2 mM glutamine for 24 h. The medium was replaced with fresh medium containing 25 mM glucose and further grown for 24 h. Size of these cells were determined by flow cytometry. Relative size of WT and AMPK-DKO cells under normal metabolic condition (25 mM glucose) (i), change in cell size of WT-MEF (ii) and DKO-MEF (iii), cultured in the presence of 25 mM glucose, 1 mM glucose or re-fed with 25 mM glucose. (b) Mitochondrial membrane potential (MMP) in MEF cells grown under the conditions mentioned in a. DiOC6 was used to determine MMP by flow cytometry. (c) MEF and cancer cells (H1299-DN and MCF7-DN) were grown under the conditions mentioned above. Mitochondrial density was determined by flow cytometry using probe MitoTracker Red FM. Mitochondrial density in WT (i), AMPK-DKO MEFs (ii), H1299 (EV and DN) (iii) and MCF7 (EV and DN) cells (iv). (d–f) MEFs (WT and DKO), H1299 (EV and DN) cells were cultured under the indicated conditions for 24 h. Citrate synthase activity (d and f) and relative ATP levels (e and g) were determined in these cells as described in Materials and Methods. Values are represented as mean±S.D. *P<0.05 and **P<0.01 denote significant differences between the groups.
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fig4: AMPK controls metabolic homeostasis in cancer cells. (a) WT and DKO MEFs were cultured in DMEM containing either 25 or 1 mM glucose and 2 mM glutamine for 24 h. The medium was replaced with fresh medium containing 25 mM glucose and further grown for 24 h. Size of these cells were determined by flow cytometry. Relative size of WT and AMPK-DKO cells under normal metabolic condition (25 mM glucose) (i), change in cell size of WT-MEF (ii) and DKO-MEF (iii), cultured in the presence of 25 mM glucose, 1 mM glucose or re-fed with 25 mM glucose. (b) Mitochondrial membrane potential (MMP) in MEF cells grown under the conditions mentioned in a. DiOC6 was used to determine MMP by flow cytometry. (c) MEF and cancer cells (H1299-DN and MCF7-DN) were grown under the conditions mentioned above. Mitochondrial density was determined by flow cytometry using probe MitoTracker Red FM. Mitochondrial density in WT (i), AMPK-DKO MEFs (ii), H1299 (EV and DN) (iii) and MCF7 (EV and DN) cells (iv). (d–f) MEFs (WT and DKO), H1299 (EV and DN) cells were cultured under the indicated conditions for 24 h. Citrate synthase activity (d and f) and relative ATP levels (e and g) were determined in these cells as described in Materials and Methods. Values are represented as mean±S.D. *P<0.05 and **P<0.01 denote significant differences between the groups.
Mentions: To explore whether AMPK is involved in maintaining metabolic and energy homeostasis, we cultured MEF cells in 25 or 1 mM glucose for 24 h, and these were replenished with 25 mM glucose thereafter. We noticed that AMPK-DKO cells are larger in size as compared with WT cells cultured in 25 mM glucose (Figure 4a-i). An increase in the cell size of WT-MEF was observed upon switching them to 1 mM glucose, while replenishing glucose-restored cell size (Figure 4a-ii). On the other hand, cell size did not alter in DKO cells under identical conditions (Figure 4a-iii). This observation suggests the involvement of AMPK in regulating cell size under metabolic stress.

View Article: PubMed Central - PubMed

ABSTRACT

Cancer cells exhibit unique metabolic response and adaptation to the fluctuating microenvironment, yet molecular and biochemical events imprinting this phenomenon are unclear. Here, we show that metabolic homeostasis and adaptation to metabolic stress in cancer cells are primarily achieved by an integrated response exerted by the activation of AMPK. We provide evidence that AMPK-p38-PGC-1&alpha; axis, by regulating energy homeostasis, maintains survival in cancer cells under glucose-limiting conditions. Functioning as a molecular switch, AMPK promotes glycolysis by activating PFK2, and facilitates mitochondrial metabolism of non-glucose carbon sources thereby maintaining cellular ATP level. Interestingly, we noted that AMPK can promote oxidative metabolism via increasing mitochondrial biogenesis and OXPHOS capacity via regulating expression of PGC-1&alpha; through p38MAPK activation. Taken together, our study signifies the fundamental role of AMPK in controlling cellular bioenergetics and mitochondrial biogenesis in cancer cells.

No MeSH data available.


Related in: MedlinePlus