AMP-activated Protein Kinase Antagonizes Pro-apoptotic Extracellular Signal-regulated Kinase Activation by Inducing Dual-specificity Protein Phosphatases in Response to Glucose Deprivation in HCT116 Carcinoma

Mitogen-activated protein kinase (MAPK) pathways are involved in the regulation of cellular responses, including cell proliferation, differentiation, cell growth, and apoptosis. Because these responses are tightly related to cellular energy level, AMP-activated protein kinase (AMPK), which plays an essential role in energy homeostasis, has emerged as another key regulator. In the present study, we demonstrate a novel signal network between AMPK and MAPK in HCT116 human colon carcinoma. Glucose deprivation activated AMPK and three MAPK subfamilies, extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38 MAPK. Under these conditions, inhibition of endogenous AMPK by expressing a dominant-negative form significantly potentiated ERK activation, indicating that glucose deprivation-induced AMPK is specifically antagonizing ERK activity in HCT116 cells. Moreover, we provide novel evidence that AMPK activity is critical for p53-dependent expression of dual-specificity phosphatase (DUSP) 1 & 2, which are negative regulators of ERK. Notably, ERK exhibits pro-apoptotic effects in HCT116 cells under glucose deprivation. Collectively, our data suggest that AMPK protects HCT116 cancer cells from glucose deprivation, in part, via inducing DUSPs, which suppresses pro-apoptotic ERK, further implying that a signal network between AMPK and ERK is a critical regulatory point in coupling the energy status of the cell to the regulation of cell survival. Mitogen-activated protein kinase (MAPK) pathways are involved in the regulation of cellular responses, including cell proliferation, differentiation, cell growth, and apoptosis. Because these responses are tightly related to cellular energy level, AMP-activated protein kinase (AMPK), which plays an essential role in energy homeostasis, has emerged as another key regulator. In the present study, we demonstrate a novel signal network between AMPK and MAPK in HCT116 human colon carcinoma. Glucose deprivation activated AMPK and three MAPK subfamilies, extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38 MAPK. Under these conditions, inhibition of endogenous AMPK by expressing a dominant-negative form significantly potentiated ERK activation, indicating that glucose deprivation-induced AMPK is specifically antagonizing ERK activity in HCT116 cells. Moreover, we provide novel evidence that AMPK activity is critical for p53-dependent expression of dual-specificity phosphatase (DUSP) 1 & 2, which are negative regulators of ERK. Notably, ERK exhibits pro-apoptotic effects in HCT116 cells under glucose deprivation. Collectively, our data suggest that AMPK protects HCT116 cancer cells from glucose deprivation, in part, via inducing DUSPs, which suppresses pro-apoptotic ERK, further implying that a signal network between AMPK and ERK is a critical regulatory point in coupling the energy status of the cell to the regulation of cell survival. IntroductionAMP-activated protein kinase (AMPK) 2The abbreviations used are: AMPKAMP-activated protein kinaseACCacetyl-CoA carboxylaseFACSfluorescence-activated cell sortingWTwild typeDNdominant negativeERKextracellular signal-regulated kinaseJNKc-Jun NH2-terminal kinaseDUSPdual-specificity phosphataseAICAR5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosideGAPDHglyceraldehyde-3-phosphate dehydrogenase. is a heterotrimeric serine/threonine kinase that consists of an α catalytic subunit and regulatory β and γ subunits, and plays a central role in cellular adaptation to ATP-depleting stresses such as glucose deprivation. Increases in the cellular AMP:ATP ratio promotes AMPK activation through allosteric binding of AMP, which changes AMPK into a better substrate for phosphoactivation via an upstream kinase. Once activated, AMPK inhibits the ATP consuming pathway, while activating ATP-generating pathways, to optimize total cellular ATP levels (1Hardie D.G. Carling D. Carlson M. Annu. Rev. Biochem. 1998; 67: 821-855Crossref PubMed Scopus (1265) Google Scholar). In fact, AMPK protects cells from ATP-depleting stresses (1Hardie D.G. Carling D. Carlson M. Annu. Rev. Biochem. 1998; 67: 821-855Crossref PubMed Scopus (1265) Google Scholar). However, a pro-apoptotic role of AMPK was also reported, and such a role is mediated, in part, by tumor suppressor proteins associated with the AMPK signaling network, such as LKB1 (2Shackelford D.B. Shaw R.J. Nat. Rev. Cancer. 2009; 9: 563-575Crossref PubMed Scopus (1297) Google Scholar), tuberous sclerosis complex (TSC2) (3Inoki K. Ouyang H. Zhu T. Lindvall C. Wang Y. Zhang X. Yang Q. Bennett C. Harada Y. Stankunas K. Wang C.Y. He X. MacDougald O.A. You M. Williams B.O. Guan K.L. Cell. 2006; 126: 955-968Abstract Full Text Full Text PDF PubMed Scopus (1025) Google Scholar), and p53 (4Jones R.G. Plas D.R. Kubek S. Buzzai M. Mu J. Xu Y. Birnbaum M.J. Thompson C.B. Mol. Cell. 2005; 18: 283-293Abstract Full Text Full Text PDF PubMed Scopus (1277) Google Scholar). Thus, an extremely sophisticated regulatory system involving AMPK exists for monitoring the level of cellular energy under stress conditions and then driving cells to either survival or apoptosis.Mitogen-activated protein kinase (MAPK) pathways are involved in the regulation of cellular responses, including cell proliferation, differentiation, cell growth, and apoptosis. Because these cellular responses are tightly related to the cellular energy level, a signal network between AMPK and MAPKs has emerged as a key regulatory point of significance. The three major subfamilies of MAPK are extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38 MAPK. In general, ERK has been implicated in the regulation of growth factor-induced cell proliferation, whereas JNK and p38 are known to contribute to stress-induced cell apoptosis (5Xia Z. Dickens M. Raingeaud J. Davis R.J. Greenberg M.E. Science. 1995; 270: 1326-1331Crossref PubMed Scopus (5027) Google Scholar, 6Paraskevas S. Aikin R. Maysinger D. Lakey J.R. Cavanagh T.J. Hering B. Wang R. Rosenberg L. FEBS Lett. 1999; 455: 203-208Crossref PubMed Scopus (74) Google Scholar, 7Sasaki K. Chiba K. Mol. Biol. Cell. 2004; 15: 1387-1396Crossref PubMed Scopus (34) Google Scholar). However, their role can vary depending upon the cell type, the stimulus, and the duration of activation (8Janes K.A. Albeck J.G. Gaudet S. Sorger P.K. Lauffenburger D.A. Yaffe M.B. Science. 2005; 310: 1646-1653Crossref PubMed Scopus (447) Google Scholar). These MAPKs are activated by dual-specific upstream kinases through reversible phosphorylation of both threonine and tyrosine resides of the TXY motif (9Waskiewicz A.J. Cooper J.A. Curr. Opin. Cell Biol. 1995; 7: 798-805Crossref PubMed Scopus (534) Google Scholar, 10Su B. Karin M. Curr. Opin. Immunol. 1996; 8: 402-411Crossref PubMed Scopus (714) Google Scholar). Conversely, the dephosphorylation of either residue is sufficient for kinase inactivation, and this is achieved largely by MAPK phosphatases, also known as dual-specificity protein phosphatases (DUSP). More than 11 different DUSPs have been identified that are highly specific for MAPKs but differ in MAPK substrate specificity (11Camps M. Nichols A. Arkinstall S. FASEB J. 2000; 14: 6-16Crossref PubMed Scopus (710) Google Scholar, 12Patterson K.I. Brummer T. O'Brien P.M. Daly R.J. Biochem. J. 2009; 418: 475-489Crossref PubMed Scopus (526) Google Scholar, 13Keyse S.M. Cancer Metastasis Rev. 2008; 27: 253-261Crossref PubMed Scopus (359) Google Scholar). Cross-talk between ERK and AMPK has been tested by several researchers, and most of these studies were performed using the artificial AMPK activator, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR). In certain cases, pharmacological activation of AMPK resulted in ERK activation, which induced proliferation of cardiac fibroblasts (14Hattori Y. Akimoto K. Nishikimi T. Matsuoka H. Kasai K. Hypertension. 2006; 47: 265-270Crossref PubMed Scopus (27) Google Scholar), catecholamine secretion in PC12 cells (15Fukuda T. Ishii K. Nanmoku T. Isobe K. Kawakami Y. Takekoshi K. J. Neuroendocrinol. 2007; 19: 621-631Crossref PubMed Scopus (17) Google Scholar), glucose transport in rat EDL muscle cells (16Chen H.C. Bandyopadhyay G. Sajan M.P. Kanoh Y. Standaert M. Farese Jr., R.V. Farese R.V. J. Biol. Chem. 2002; 277: 23554-23562Abstract Full Text Full Text PDF PubMed Scopus (162) Google Scholar), potentiation of insulin signaling in rat heart (17Longnus S.L. Ségalen C. Giudicelli J. Sajan M.P. Farese R.V. Van Obberghen E. Diabetologia. 2005; 48: 2591-2601Crossref PubMed Scopus (53) Google Scholar), and suppression of protein synthesis in C2C12 myotubes (18Williamson D.L. Bolster D.R. Kimball S.R. Jefferson L.S. Am. J. Physiol. Endocrinol. Metab. 2006; 291: E80-E89Crossref PubMed Scopus (77) Google Scholar). In contrast, ERK activity induced by IGF-1 (19Kim J. Yoon M.Y. Choi S.L. Kang I. Kim S.S. Kim Y.S. Choi Y.K. Ha J. J. Biol. Chem. 2001; 276: 19102-19110Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar), angiotensin II (20Nagata D. Takeda R. Sata M. Satonaka H. Suzuki E. Nagano T. Hirata Y. Circulation. 2004; 110: 444-451Crossref PubMed Scopus (180) Google Scholar), or transaortic constriction (21Li H.L. Yin R. Chen D. Liu D. Wang D. Yang Q. Dong Y.G. J. Cell. Biochem. 2007; 100: 1086-1099Crossref PubMed Scopus (100) Google Scholar), was down-regulated by AICAR. Consequently, the molecular mechanisms that link the two signal pathways remain unclear.We therefore examined the role of AMPK on the regulation of ERK in HCT116 human colon carcinoma under physiologically relevant conditions that activate both AMPK and ERK. As solid tumors outgrow the existing vasculature, they are continuously exposed to nutrient-depleted microenvironments, such as glucose deprivation, and must adapt to such environments for survival. Here, we demonstrate that AMPK induces the expression of DUSP 1 & 2 via p53 activation under glucose deprivation, which leads to suppression of ERK activity. Notably, the glucose deprivation-induced ERK activity is pro-apoptotic. Collectively, our data suggest that AMPK protects HCT116 cancer cells from glucose deprivation, in part, via induction of DUSPs, which suppresses pro-apoptotic ERK.DISCUSSIONRecently, a number of attempts have been made to reveal a relationship between AMPK and ERK signal pathways, but there is no consensus on how two signal pathways interact (14Hattori Y. Akimoto K. Nishikimi T. Matsuoka H. Kasai K. Hypertension. 2006; 47: 265-270Crossref PubMed Scopus (27) Google Scholar, 15Fukuda T. Ishii K. Nanmoku T. Isobe K. Kawakami Y. Takekoshi K. J. Neuroendocrinol. 2007; 19: 621-631Crossref PubMed Scopus (17) Google Scholar, 16Chen H.C. Bandyopadhyay G. Sajan M.P. Kanoh Y. Standaert M. Farese Jr., R.V. Farese R.V. J. Biol. Chem. 2002; 277: 23554-23562Abstract Full Text Full Text PDF PubMed Scopus (162) Google Scholar, 17Longnus S.L. Ségalen C. Giudicelli J. Sajan M.P. Farese R.V. Van Obberghen E. Diabetologia. 2005; 48: 2591-2601Crossref PubMed Scopus (53) Google Scholar, 18Williamson D.L. Bolster D.R. Kimball S.R. Jefferson L.S. Am. J. Physiol. Endocrinol. Metab. 2006; 291: E80-E89Crossref PubMed Scopus (77) Google Scholar, 19Kim J. Yoon M.Y. Choi S.L. Kang I. Kim S.S. Kim Y.S. Choi Y.K. Ha J. J. Biol. Chem. 2001; 276: 19102-19110Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar, 20Nagata D. Takeda R. Sata M. Satonaka H. Suzuki E. Nagano T. Hirata Y. Circulation. 2004; 110: 444-451Crossref PubMed Scopus (180) Google Scholar, 21Li H.L. Yin R. Chen D. Liu D. Wang D. Yang Q. Dong Y.G. J. Cell. Biochem. 2007; 100: 1086-1099Crossref PubMed Scopus (100) Google Scholar). In most of these studies, an artificial AMPK activator, AICAR, has been used to determine its role in different cells and tissues. AICAR is converted to ZMP in a cell, thereby acting as an AMP analogue and activating AMPK. For this reason, AICAR has been widely used to demonstrate the role of AMPK, but it exerts adverse effects. Here, we demonstrated that glucose deprivation activated both AMPK and ERK in HCT116 colon cancer cells. Inhibition of AMPK by AMPK-DN significantly potentiated ERK activation, indicating that AMPK normally suppresses ERK activity. Moreover, we provide novel evidence that AMPK activity is critical for inducing DUSPs expression, which are negative regulators of ERK. In contrast to a general perception that ERK mediates anti-apoptotic effects, our results with two different MEK inhibitors revealed that ERK exerts pro-apoptotic effects in HCT116 cells after glucose deprivation (Fig. 9). Indeed, ERK acts as a survival factor under Fas (CD95/Apo1)-, serum-, and insulin-treated conditions in the same cells (Fig. 9). Because inhibition of AMPK potentiated glucose deprivation-induced apoptosis and increased pro-apoptotic ERK, we concluded that AMPK protects HCT116 cells from glucose deprivation via suppressing ERK. Indeed, ERK can function in a pro-apoptotic manner under different stimuli in different tissues, and ERK-mediated cell death was also reported in many animal models (32Lu Z. Xu S. IUBMB Life. 2006; 58: 621-631Crossref PubMed Scopus (470) Google Scholar, 33Zhuang S. Schnellmann R.G. J Pharmacol. Exp. Ther. 2006; 319: 991-997Crossref PubMed Scopus (318) Google Scholar). As a downstream effector of cell death-promoting ERK, cellular components involved in intrinsic as well as extrinsic apoptosis pathway have been suggested. The suppression of survival pathways such as phosphatidylinositol 3-kinase/Akt could mediate ERK-induced apoptosis (33Zhuang S. Schnellmann R.G. J Pharmacol. Exp. Ther. 2006; 319: 991-997Crossref PubMed Scopus (318) Google Scholar). Furthermore, the kinetics and duration of ERK activation, its subcellular localization, and model system, affect cell fate (32Lu Z. Xu S. IUBMB Life. 2006; 58: 621-631Crossref PubMed Scopus (470) Google Scholar, 34Fan M. Chambers T.C. Drug Resist. Updat. 2001; 4: 253-267Crossref PubMed Scopus (171) Google Scholar, 35Shaul Y.D. Seger R. Biochim. Biophys. Acta. 2007; 1773: 1213-1226Crossref PubMed Scopus (687) Google Scholar). Nevertheless, the mechanism by which ERK executes anti- or pro-apoptotic function is from to ERK, AMPK has a role in cell growth and apoptosis. AMPK plays a central role for energy in to anti-apoptotic R. K. D.R. Y. S. K. T. K. Nat. 2005; PubMed Scopus Google Scholar, M. M. S. S. H. Wang K. E. E. E. T. FASEB J. 2009; PubMed Scopus Google Scholar). a pro-apoptotic function of AMPK was also AMPK can cell growth via tumor as of the upstream activating AMPK LKB1 is a tumor suppressor and its a a cancer J. L. D.R. D.G. J. Biol. PubMed Google Scholar, A. Carling D. Carlson M. 100: PubMed Scopus Google Scholar, A. S.R. K. D. T. Carlson M. Carling D. Curr. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). The tumor suppressor is a substrate of AMPK, a link between AMPK activation and the suppression of protein synthesis (3Inoki K. Ouyang H. Zhu T. Lindvall C. Wang Y. Zhang X. Yang Q. Bennett C. Harada Y. Stankunas K. Wang C.Y. He X. MacDougald O.A. You M. Williams B.O. Guan K.L. Cell. 2006; 126: 955-968Abstract Full Text Full Text PDF PubMed Scopus (1025) Google Scholar, K. Zhu T. Guan K.L. Cell. Full Text Full Text PDF PubMed Scopus Google Scholar, K. Guan K.L. 2004; 18: PubMed Scopus Google Scholar). Moreover, there are several a between AMPK and tumor suppressor p53 (4Jones R.G. Plas D.R. Kubek S. Buzzai M. Mu J. Xu Y. Birnbaum M.J. Thompson C.B. Mol. Cell. 2005; 18: 283-293Abstract Full Text Full Text PDF PubMed Scopus (1277) Google Scholar, R. T. H. K. S. T. T. A. H. J. Biol. Chem. 2008; Full Text Full Text PDF PubMed Scopus Google Scholar, C. S. R. B. E. A. T. Guan K.L. Y. J. Biol. Chem. 2008; Full Text Full Text PDF PubMed Scopus (100) Google Scholar). In to of AMPK, our data an that AMPK can either anti- or pro-apoptotic role through ERK. For we demonstrated that AMPK suppresses pro-apoptotic ERK in HCT116 cells after glucose deprivation, but we and reported that AMPK can ERK to cell pharmacological activation of AMPK by AICAR inhibits or ERK activation (19Kim J. Yoon M.Y. Choi S.L. Kang I. Kim S.S. Kim Y.S. Choi Y.K. Ha J. J. Biol. Chem. 2001; 276: 19102-19110Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar, 20Nagata D. Takeda R. Sata M. Satonaka H. Suzuki E. Nagano T. Hirata Y. Circulation. 2004; 110: 444-451Crossref PubMed Scopus (180) Google Scholar). More than ERK have been including protein protein phosphatases, and of it highly to AMPK activation under different conditions can affect of ERK downstream and determine the of ERK activation on cell the kinase also AMPK signal suppresses LKB1 and AMPK function in cells B. S.R. L. Mol. Cell. 2009; Full Text Full Text PDF PubMed Scopus Google Scholar). Because both LKB1 and AMPK cell growth, suppression of by could tumor cells to growth by signaling for cell AMPK via ERK activation in rat cardiac fibroblasts J. Guan T. Zhang H. Y. Liu Zhang Y. Biochem. Biophys. 2008; PubMed Scopus Google Scholar). Thus, a highly complex and sophisticated signaling network to AMPK and ERK activity. ERK signaling is involved in the regulation of cell proliferation, differentiation, cell and changes in ATP and AMP levels in these cellular Thus, our results suggest that a signal network that AMPK and ERK plays a central role in energy levels to the regulation of a of cellular this study, we have that AMPK induces in a p53-dependent The of AMPK inhibition on the DUSP its and ERK phosphorylation was in but cells. In the of p53 into cells the of AMPK indicating that p53 acts as a downstream of AMPK. However, the mechanism p53 and AMPK was reported that p53 phosphorylation was essential for the of AMPK on p53-dependent cell of but p53 is in human cells after glucose deprivation (4Jones R.G. Plas D.R. Kubek S. Buzzai M. Mu J. Xu Y. Birnbaum M.J. Thompson C.B. Mol. Cell. 2005; 18: 283-293Abstract Full Text Full Text PDF PubMed Scopus (1277) Google Scholar, R. T. H. K. S. T. T. A. H. J. Biol. Chem. 2008; Full Text Full Text PDF PubMed Scopus Google Scholar). we that is for regulation by AMPK, studies are for the regulatory mechanisms between AMPK and Indeed, AMPK p53 under conditions S. K. I. J. Wang J. M. Mol. Cell. Biol. PubMed Scopus Google Scholar). Moreover, p53 can the phosphorylation of or expression of AMPK indicating a Z. E. S. S. A.J. Cancer 2007; 67: PubMed Scopus Google Scholar, Karin M. Cell. 2008; Full Text Full Text PDF PubMed Scopus Google in MAPK signaling pathways in a of human and of was in the of and in tumors of and in of in of the and is associated with a in of survival S.M. Cancer Metastasis Rev. 2008; 27: 253-261Crossref PubMed Scopus (359) Google Scholar). further studies on the novel signaling network of AMPK, DUSPs, and our of the and of IntroductionAMP-activated protein kinase (AMPK) 2The abbreviations used are: AMPKAMP-activated protein kinaseACCacetyl-CoA carboxylaseFACSfluorescence-activated cell sortingWTwild typeDNdominant negativeERKextracellular signal-regulated kinaseJNKc-Jun NH2-terminal kinaseDUSPdual-specificity phosphataseAICAR5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosideGAPDHglyceraldehyde-3-phosphate dehydrogenase. is a heterotrimeric serine/threonine kinase that consists of an α catalytic subunit and regulatory β and γ subunits, and plays a central role in cellular adaptation to ATP-depleting stresses such as glucose deprivation. Increases in the cellular AMP:ATP ratio promotes AMPK activation through allosteric binding of AMP, which changes AMPK into a better substrate for phosphoactivation via an upstream kinase. Once activated, AMPK inhibits the ATP consuming pathway, while activating ATP-generating pathways, to optimize total cellular ATP levels (1Hardie D.G. Carling D. Carlson M. Annu. Rev. Biochem. 1998; 67: 821-855Crossref PubMed Scopus (1265) Google Scholar). In fact, AMPK protects cells from ATP-depleting stresses (1Hardie D.G. Carling D. Carlson M. Annu. Rev. Biochem. 1998; 67: 821-855Crossref PubMed Scopus (1265) Google Scholar). However, a pro-apoptotic role of AMPK was also reported, and such a role is mediated, in part, by tumor suppressor proteins associated with the AMPK signaling network, such as LKB1 (2Shackelford D.B. Shaw R.J. Nat. Rev. Cancer. 2009; 9: 563-575Crossref PubMed Scopus (1297) Google Scholar), tuberous sclerosis complex (TSC2) (3Inoki K. Ouyang H. Zhu T. Lindvall C. Wang Y. Zhang X. Yang Q. Bennett C. Harada Y. Stankunas K. Wang C.Y. He X. MacDougald O.A. You M. Williams B.O. Guan K.L. Cell. 2006; 126: 955-968Abstract Full Text Full Text PDF PubMed Scopus (1025) Google Scholar), and p53 (4Jones R.G. Plas D.R. Kubek S. Buzzai M. Mu J. Xu Y. Birnbaum M.J. Thompson C.B. Mol. Cell. 2005; 18: 283-293Abstract Full Text Full Text PDF PubMed Scopus (1277) Google Scholar). Thus, an extremely sophisticated regulatory system involving AMPK exists for monitoring the level of cellular energy under stress conditions and then driving cells to either survival or apoptosis.Mitogen-activated protein kinase (MAPK) pathways are involved in the regulation of cellular responses, including cell proliferation, differentiation, cell growth, and apoptosis. Because these cellular responses are tightly related to the cellular energy level, a signal network between AMPK and MAPKs has emerged as a key regulatory point of significance. The three major subfamilies of MAPK are extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38 MAPK. In general, ERK has been implicated in the regulation of growth factor-induced cell proliferation, whereas JNK and p38 are known to contribute to stress-induced cell apoptosis (5Xia Z. Dickens M. Raingeaud J. Davis R.J. Greenberg M.E. Science. 1995; 270: 1326-1331Crossref PubMed Scopus (5027) Google Scholar, 6Paraskevas S. Aikin R. Maysinger D. Lakey J.R. Cavanagh T.J. Hering B. Wang R. Rosenberg L. FEBS Lett. 1999; 455: 203-208Crossref PubMed Scopus (74) Google Scholar, 7Sasaki K. Chiba K. Mol. Biol. Cell. 2004; 15: 1387-1396Crossref PubMed Scopus (34) Google Scholar). However, their role can vary depending upon the cell type, the stimulus, and the duration of activation (8Janes K.A. Albeck J.G. Gaudet S. Sorger P.K. Lauffenburger D.A. Yaffe M.B. Science. 2005; 310: 1646-1653Crossref PubMed Scopus (447) Google Scholar). These MAPKs are activated by dual-specific upstream kinases through reversible phosphorylation of both threonine and tyrosine resides of the TXY motif (9Waskiewicz A.J. Cooper J.A. Curr. Opin. Cell Biol. 1995; 7: 798-805Crossref PubMed Scopus (534) Google Scholar, 10Su B. Karin M. Curr. Opin. Immunol. 1996; 8: 402-411Crossref PubMed Scopus (714) Google Scholar). Conversely, the dephosphorylation of either residue is sufficient for kinase inactivation, and this is achieved largely by MAPK phosphatases, also known as dual-specificity protein phosphatases (DUSP). More than 11 different DUSPs have been identified that are highly specific for MAPKs but differ in MAPK substrate specificity (11Camps M. Nichols A. Arkinstall S. FASEB J. 2000; 14: 6-16Crossref PubMed Scopus (710) Google Scholar, 12Patterson K.I. Brummer T. O'Brien P.M. Daly R.J. Biochem. J. 2009; 418: 475-489Crossref PubMed Scopus (526) Google Scholar, 13Keyse S.M. Cancer Metastasis Rev. 2008; 27: 253-261Crossref PubMed Scopus (359) Google Scholar). Cross-talk between ERK and AMPK has been tested by several researchers, and most of these studies were performed using the artificial AMPK activator, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR). In certain cases, pharmacological activation of AMPK resulted in ERK activation, which induced proliferation of cardiac fibroblasts (14Hattori Y. Akimoto K. Nishikimi T. Matsuoka H. Kasai K. Hypertension. 2006; 47: 265-270Crossref PubMed Scopus (27) Google Scholar), catecholamine secretion in PC12 cells (15Fukuda T. Ishii K. Nanmoku T. Isobe K. Kawakami Y. Takekoshi K. J. Neuroendocrinol. 2007; 19: 621-631Crossref PubMed Scopus (17) Google Scholar), glucose transport in rat EDL muscle cells (16Chen H.C. Bandyopadhyay G. Sajan M.P. Kanoh Y. Standaert M. Farese Jr., R.V. Farese R.V. J. Biol. Chem. 2002; 277: 23554-23562Abstract Full Text Full Text PDF PubMed Scopus (162) Google Scholar), potentiation of insulin signaling in rat heart (17Longnus S.L. Ségalen C. Giudicelli J. Sajan M.P. Farese R.V. Van Obberghen E. Diabetologia. 2005; 48: 2591-2601Crossref PubMed Scopus (53) Google Scholar), and suppression of protein synthesis in C2C12 myotubes (18Williamson D.L. Bolster D.R. Kimball S.R. Jefferson L.S. Am. J. Physiol. Endocrinol. Metab. 2006; 291: E80-E89Crossref PubMed Scopus (77) Google Scholar). In contrast, ERK activity induced by IGF-1 (19Kim J. Yoon M.Y. Choi S.L. Kang I. Kim S.S. Kim Y.S. Choi Y.K. Ha J. J. Biol. Chem. 2001; 276: 19102-19110Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar), angiotensin II (20Nagata D. Takeda R. Sata M. Satonaka H. Suzuki E. Nagano T. Hirata Y. Circulation. 2004; 110: 444-451Crossref PubMed Scopus (180) Google Scholar), or transaortic constriction (21Li H.L. Yin R. Chen D. Liu D. Wang D. Yang Q. Dong Y.G. J. Cell. Biochem. 2007; 100: 1086-1099Crossref PubMed Scopus (100) Google Scholar), was down-regulated by AICAR. Consequently, the molecular mechanisms that link the two signal pathways remain unclear.We therefore examined the role of AMPK on the regulation of ERK in HCT116 human colon carcinoma under physiologically relevant conditions that activate both AMPK and ERK. As solid tumors outgrow the existing vasculature, they are continuously exposed to nutrient-depleted microenvironments, such as glucose deprivation, and must adapt to such environments for survival. Here, we demonstrate that AMPK induces the expression of DUSP 1 & 2 via p53 activation under glucose deprivation, which leads to suppression of ERK activity. Notably, the glucose deprivation-induced ERK activity is pro-apoptotic. Collectively, our data suggest that AMPK protects HCT116 cancer cells from glucose deprivation, in part, via induction of DUSPs, which suppresses pro-apoptotic ERK.