Gene Summary

Gene:ATIC; 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase
Summary:This gene encodes a bifunctional protein that catalyzes the last two steps of the de novo purine biosynthetic pathway. The N-terminal domain has phosphoribosylaminoimidazolecarboxamide formyltransferase activity, and the C-terminal domain has IMP cyclohydrolase activity. A mutation in this gene results in AICA-ribosiduria. [provided by RefSeq, Sep 2009]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:bifunctional purine biosynthesis protein PURH
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 September 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Nucleotide Deaminases
  • Polymerase Chain Reaction
  • ALK
  • Phosphoribosylaminoimidazolecarboxamide Formyltransferase
  • Transfection
  • FISH
  • Ribonucleotides
  • Childhood Cancer
  • Phosphoribosylglycinamide Formyltransferase
  • Immunohistochemistry
  • ALK
  • Chromosome 2
  • Lung Cancer
  • Myosin Heavy Chains
  • Smoking
  • Chromosome Inversion
  • Molecular Motor Proteins
  • inosine monophosphate synthase
  • Cancer DNA
  • gamma-Glutamyl Hydrolase
  • Lymphoma, Large-Cell, Anaplastic
  • Young Adult
  • Diffuse Large B-Cell Lymphoma
  • Multienzyme Complexes
  • Adenocarcinoma
  • Adolescents
  • Bladder Cancer
  • Tropomyosin
  • Signal Transduction
  • Translocation
  • Protein-Tyrosine Kinases
  • Non-Hodgkin Lymphoma
  • Base Sequence
  • Hodgkin Lymphoma
  • Oncogene Fusion Proteins
  • Staging
  • Amino Acid Sequence
  • Hydroxymethyl and Formyl Transferases
  • Receptor Protein-Tyrosine Kinases
  • Messenger RNA
  • Cloning, Molecular
  • Ubiquitin-Protein Ligases
Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: ATIC (cancer-related)

Nishimura T, Nakata A, Chen X, et al.
Cancer stem-like properties and gefitinib resistance are dependent on purine synthetic metabolism mediated by the mitochondrial enzyme MTHFD2.
Oncogene. 2019; 38(14):2464-2481 [PubMed] Free Access to Full Article Related Publications
Tumor recurrence is attributable to cancer stem-like cells (CSCs), the metabolic mechanisms of which currently remain obscure. Here, we uncovered the critical role of folate-mediated one-carbon (1C) metabolism involving mitochondrial methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) and its downstream purine synthesis pathway. MTHFD2 knockdown greatly reduced tumorigenesis and stem-like properties, which were associated with purine nucleotide deficiency, and caused marked accumulation of 5-aminoimidazole carboxamide ribonucleotide (AICAR)-the final intermediate of the purine synthesis pathway. Lung cancer cells with acquired resistance to the targeted drug gefitinib, caused by elevated expression of components of the β-catenin pathway, exhibited increased stem-like properties and enhanced expression of MTHFD2. MTHFD2 knockdown or treatment with AICAR reduced the stem-like properties and restored gefitinib sensitivity in these gefitinib-resistant cancer cells. Moreover, overexpression of MTHFD2 in gefitinib-sensitive lung cancer cells conferred resistance to gefitinib. Thus, MTHFD2-mediated mitochondrial 1C metabolism appears critical for cancer stem-like properties and resistance to drugs including gefitinib through consumption of AICAR, leading to depletion of the intracellular pool of AICAR. Because CSCs are dependent on MTHFD2, therapies targeting MTHFD2 may eradicate tumors and prevent recurrence.

Kou B, Kou Q, Ma B, et al.
Thymoquinone inhibits metastatic phenotype and epithelial‑mesenchymal transition in renal cell carcinoma by regulating the LKB1/AMPK signaling pathway.
Oncol Rep. 2018; 40(3):1443-1450 [PubMed] Related Publications
Thymoquinone, isolated from the seeds of Nigella sativa, has exhibited antitumor properties in a variety of cancer types. However, few studies have investigated the effect of thymoquinone (TQ) on migration and invasion in renal cell carcinoma (RCC). In the present study, our results confirmed that TQ significantly inhibited the migration and invasion of the human RCC 769‑P and 786‑O cell lines, as demonstrated by wound healing and Transwell assays. Additionally, TQ upregulated the expression of E‑cadherin and downregulated the expression of Snail, ZEB1 and vimentin at the mRNA and protein levels in a concentration‑dependent manner. Subsequently, the phosphorylation levels of liver kinase B1 (LKB1) and AMP‑activated protein kinase (AMPK) were increased upon TQ treatment. To further validate the role of LKB1/AMPK signaling, we revealed that TQ‑mediated increase of E‑cadherin level and reduction of Snail level could be further enhanced by LKB1 overexpression. Furthermore, co‑treatment with the AMPK inhibitor Compound C attenuated the anti‑metastatic effect of TQ on RCC and partially abrogated the high expression of E‑cadherin and the low expression of Snail mediated by TQ. In contrast, the AMPK activator AICAR demonstrated the opposite effect. Collectively, the present study revealed that TQ could markedly suppress the metastatic phenotype and reverse the epithelial‑mesenchymal transition in RCC by regulating the LKB1/AMPK signaling pathway, indicating that TQ may be a potential therapeutic candidate against RCC.

Parker BM, Parker JV, Lymperopoulos A, Konda V
A case report: Pharmacology and resistance patterns of three generations of ALK inhibitors in metastatic inflammatory myofibroblastic sarcoma.
J Oncol Pharm Pract. 2019; 25(5):1226-1230 [PubMed] Related Publications
BACKGROUND: Little exists currently in research about the mechanisms of resistance of ALK inhibitors in inflammatory myofibroblastic sarcoma. It is known, however, that ALK gene rearrangements are common in inflammatory myofibroblastic tumors, similar to non-small cell lung cancer. In roughly 50% of inflammatory myofibroblastic tumors, gene rearrangement has been found to occur on chromosome 2 at band 2p23. In non-small cell lung cancer, it has been shown that about a third of patients who progress on the first generation ALK inhibitor, crizotinib develops mutations in the ALK kinase domain. The remaining two-thirds of patients tend to develop amplification of ALK or activation of alternative signaling pathways. Chromoplexy has also been described as a mechanism of resistance, where multiple closed chain rearrangements cause loss-of-function of tumor suppressor genes and gain-in-function of oncogenic fusions. Partner genes that have been identified in IMTs are tropomyosin 3 (TPM3), tropomyosin 4 (TPM4), clathrin heavy chain (CLTC), Ran-binding protein 2 (RANBP2), cysteinyl-tRNA synthetase (CARS), 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (ATIC), and SEC31L1. All are active promoters for the fusion gene, in response to NPM binding. Several inflammatory myofibroblastic tumor case reports indicated that fusion of ALK and RANBP2 led to a more aggressive clinical course. Although the majority of inflammatory myofibroblastic tumor case reports have utilized first and second generation ALK inhibitors, all generations of ALK inhibitors have demonstrated some ability to impair disease progression and extend life expectancy. However, at some point in the course of therapy with each generation of ALK inhibitor, resistance ultimately developed. In order to better understand the pharmacology and resistance patterns behind three generations of ALK inhibitors, we sought to examine a patient with metastatic anaplastic lymphoma kinase-1-rearranged inflammatory myofibroblastic sarcoma to the brain. We also explored the similarities and differences of this clinical case to other inflammatory myofibroblastic sarcoma case reports involving the use of ALK inhibitors.
CASE REPORT: A rare case of pulmonary IMS with ALK-1 gene rearrangement and multiple brain metastases responded to three generations of ALK inhibitors. However, similar to other case reports, due to the development of resistance and recurrence, the patient eventually succumbed to the disease.
CONCLUSIONS: ALK inhibitors are beneficial in the temporary prevention of progression of disease in patients with inflammatory myofibroblastic tumors. In this case, due to the inability to reveal the fusion partner in this patient via DNA sequencing, it is unknown exactly if that partner was RANBP2 or another ALK partner gene. Brain biopsy tissue was also unobtainable during sequence of ALK due to risk versus benefit, which would have provided insight as which type of ALK resistance mutations the patient was developing. It is likely that this patient had some form of chromoplexy occurring.

Wandee J, Prawan A, Senggunprai L, et al.
Metformin enhances cisplatin induced inhibition of cholangiocarcinoma cells via AMPK-mTOR pathway.
Life Sci. 2018; 207:172-183 [PubMed] Related Publications
AIMS: AMP-activated protein kinase (AMPK) functions as a cellular energy sensor regulating various aspects of cellular metabolism. Metformin (Met), an activator of AMPK, has been reported to reduce the cancer risk and enhance antitumor effects in certain cancers. Cholangiocarcinoma (CCA) is an aggressive malignancy which rarely responds to chemotherapeutic agents. We investigated the chemosensitizing effects of Met in CCA cells.
MATERIALS AND METHODS: KKU-100 and KKU-452 cells were used in the study. Antiproliferation of Met and cisplatin (Cis) was analyzed by sulforhodamine B and colony forming assays. Apoptotic cell death was analyzed by acridine orange and ethidium bromide staining method. Cell cycle analysis was performed by flow cytometric method. Effects on cell migration and invasion were analyzed by wound healing assay and transwell chamber method. Expression of proteins was examined by western blot analysis.
KEY FINDINGS: Met enhanced the antiproliferation of Cis, and conferred antimigration and anti-invasion in CCA cells, where Cis alone did not have two latter effects. This chemosensitizing effect is related to the activation of AMPK and suppression of Akt, mTOR and p70S6K. Met and Cis increased expression of p53 and p21 and suppressed expression of cyclin D1. This effect was associated with cell cycle arrest at S phase. The anti-invasion effect was casually associated with the suppression of FAK expression. The cytotoxic effect of the drug combination was mimicked by AICAR, an AMPK agonist.
SIGNIFICANCE: Met may be a novel agent to increase the efficacy of Cis to treat CCA.

Shin EJ, Choi HK, Sung MJ, et al.
Anti-tumour effects of beta-sitosterol are mediated by AMPK/PTEN/HSP90 axis in AGS human gastric adenocarcinoma cells and xenograft mouse models.
Biochem Pharmacol. 2018; 152:60-70 [PubMed] Related Publications
We investigated the anti-cancer effects of beta-sitosterol (BS), a plant-derived sterol in AGS human gastric adenocarcinoma cells and xenograft mouse models. BS significantly reduced cell viability by inducing apoptosis in AGS adenocarcinoma cells. This was accompanied by the formation of apoptotic bodies, as detected by Annexin V, caspase 3/7 activity, and MitoPotential assay. BS stimulated phosphatase and tensin homolog (PTEN) and phospho-AMP-activated protein kinase (p-AMPK) expression. Pharmacological inhibitors or siRNA were used to further analyse the relationship between the two proteins. AMPK was found to represent a likely upstream regulator of PTEN. Additionally, two-dimensional gel electrophoresis was used to identify related proteins in the treatment of BS. The decrease of Hsp90 protein by BS was observed. Induction of PTEN protein and reduction of Hsp90 was mediated by AICAR, an AMPK activator, indicating that AMPK is necessary for PTEN and Hsp90 expression. Additionally, BS was found to be effective through the regulation of cancer biomarker. Furthermore, BS suppressed tumour growth without toxicity in the AGS xenograft mouse models-. Taken together, the present results demonstrate that BS exerts anti-cancer effects in AGS cells and xenograft mouse models by mediating AMPK, PTEN, and Hsp90.

Li M, Jin C, Xu M, et al.
Bifunctional enzyme ATIC promotes propagation of hepatocellular carcinoma by regulating AMPK-mTOR-S6 K1 signaling.
Cell Commun Signal. 2017; 15(1):52 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Hepatocellular carcinoma (HCC) is one of the cancer types with poor prognosis. To effectively treat HCC, new molecular targets and therapeutic approaches must be identified. 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/inosine monophosphate (IMP) cyclohydrolase (ATIC), a bifunctional protein enzyme, catalyzes the last two steps of the de novo purine biosynthetic pathway. Whether ATIC contributes to cancer development remains unclear.
METHODS: ATIC mRNA levels in different types of human HCC samples or normal tissues were determined from Gene Expression across Normal and Tumor tissue (GENT) database. The expression level of ATIC in human HCC samples or cell lines were examined by RT-PCR and western blot. Overall survival and disease-free survival of HCC patients in the ATIC low and ATIC high groups were determined by Kaplan-Meier analysis. Effects of ATIC knockdown by lentivirus infection were evaluated on cell-proliferation, cell-apoptosis, colony formation and migration. The mechanisms involved in HCC cells growth, apoptosis and migration were analyzed by western blot and Compound C (C-C) rescue assays.
RESULTS: Here, we first demonstrated that expression of ATIC is aberrantly up-regulated in HCC tissues and high level of ATIC is correlated with poor survival in HCC patients. Knockdown of ATIC expression resulted in a dramatic decrease in proliferation, colony formation and migration of HCC cells. We also identified ATIC as a novel regulator of adenosine monophosphate-activated protein kinase (AMPK) and its downstream signaling mammalian target of rapamycin (mTOR). ATIC suppresses AMPK activation, thus activates mTOR-S6 K1-S6 signaling and supports growth and motility activity of HCC cells.
CONCLUSION: Taken together, our results indicate that ATIC acts as an oncogenic gene that promotes survival, proliferation and migration by targeting AMPK-mTOR-S6 K1 signaling.

Kou B, Liu W, Xu X, et al.
Autophagy induction enhances tetrandrine-induced apoptosis via the AMPK/mTOR pathway in human bladder cancer cells.
Oncol Rep. 2017; 38(5):3137-3143 [PubMed] Related Publications
Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the roots of Stephania tetrandra is a traditional Chinese medicine and exerts anticancer capacity in various types of cancers. Previous studies have shown that tetrandrine induces apoptosis in bladder cancer cells via activation of the caspase cascade. However, the underlying mechanism has not yet been reported. Autophagy is a cellular process involved in the degradation of broken proteins and aging organelles to maintain homeostasis. Recent studies indicate that autophagy is implicated in cancer therapy. Thus, we focused on the correlation between autophagy and apoptosis upon tetrandrine treatment in human bladder cancer cells. Firstly, our results observed a marked increase in autophagic double-membrane vacuoles and fluorescent puncta of red fluorescence protein-green fluorescence protein-LC3 (GRP-RFP-LC3) upon tetrandrine treatment, as evidenced by transmission electron microscopy and confocal fluorescence microscopy. Secondly, the expression of LC3-II was increased in tetrandrine-treated T24 and 5637 cells in a time- and concentration-dependent manner. Subsequently, downregulation of p62 and LC3 turnover assay further confirmed that tetrandrine induced autophagic flux in bladder cancer T24 and 5637 cells. Thirdly, the protein levels of phosphorylated-AMP-activated protein kinase (AMPK) and phosphorylated-acetyl-coenzyme A carboxylase (ACC) were upregulated in the tetrandrine-treated cells, while the mammalian target of rapamycin (mTOR)-related proteins were downregulated. Moreover, AICAR, a common AMPK activator, further increased the expression the LC3-II, while AMPK inhibitor compound C partially reversed the LC3-II protein levels in bladder cancer T24 cells. Finally, AICAR significantly reinforced the growth inhibition and apoptosis induction of tetrandrine in T24 and 5637 cells, while compound C had an opposite effect, suggesting that AMPK-mediated autophagy enhanced the cytotoxic and pro-apoptosis effect of tetrandrine in human bladder cancer cells. Taken together, the present study showed that tetrandrine induced autophagy in human bladder cancer cells by regulating the AMPK/mTOR signaling pathway, which contributed to the apoptosis induction by tetrandrine, indicating that tetrandrine may be a potential anticancer candidate for the treatment of bladder cancer, and autophagy may be a possible mechanism for cancer therapy.

Tao X, Chen L, Cai L, et al.
Regulatory effects of the AMPKα-SIRT1 molecular pathway on insulin resistance in PCOS mice: An in vitro and in vivo study.
Biochem Biophys Res Commun. 2017; 494(3-4):615-620 [PubMed] Related Publications
In order to preliminarily explore the correlation between the AMPKα-SIRT1 pathway and insulin resistance and reproductive function in PCOS mice and find the pathogenesis molecular mechanism and potential therapeutic target of PCOS, we carried out in vitro study of human granulosa KGN cells and in vivo study of PCOS mouse model which was constructed with DHEA, and AICAR and Compound C were applied. We have found that SIRT1 and AMPKα expression in KGN cells gradually decreased as DHEA concentration increased; Mice of the PCOS model were in an obvious status of IR (P < 0.05). Granulosa cells in their ovarian were present in fewer numbers and were disorderly arranged, their numbers of immature follicles were significantly increased, and their AMPKα-SIRT1 pathways were down-regulated. The AMPKα-SIRT1 pathway could be up-regulated after AICAR treatment, resulting in improved IR status (P < 0.0001); however, the abovementioned effect was blocked by Compound C. Thus we concluded that the AMPKα-SIRT1 molecular pathway may be a molecular mechanism of IR in PCOS and may serve as a therapeutic target for the development of potential treatments for improving metabolic and reproductive function in PCOS.

van der Krogt JA, Bempt MV, Ferreiro JF, et al.
Anaplastic lymphoma kinase-positive anaplastic large cell lymphoma with the variant RNF213-, ATIC- and TPM3-ALK fusions is characterized by copy number gain of the rearranged ALK gene.
Haematologica. 2017; 102(9):1605-1616 [PubMed] Free Access to Full Article Related Publications
Anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma is characterized by 2p23/

Park JA, Shin HY
ATIC Gene Polymorphism and Histologic Response to Chemotherapy in Pediatric Osteosarcoma.
J Pediatr Hematol Oncol. 2017; 39(5):e270-e274 [PubMed] Related Publications
Accumulating evidence indicates that polymorphisms in folate pathway genes play a role in response to methotrexate (MTX) treatment in various diseases. This study explored the influence of these genetic polymorphisms on treatment outcome in pediatric osteosarcoma. Blood and tissue samples from 48 osteosarcoma patients were obtained, and the following polymorphisms were analyzed; SLC19A1 80G>A, DHFR 829C>T, MTHFR 677C>T, MTHFR 1298A>C, and ATIC 347C>G. We evaluated associations between these candidate gene polymorphisms and treatment outcome, including histologic response and event-free and overall survival, of patients treated with high-dose MTX. Patients with ATIC 347C>G exhibited a good histologic response to chemotherapy (odds ratio, 0.13; 95% confidence interval, 0.017-0.978; P=0.048). However, none of these single nucleotide polymorphisms we examined affected event-free survival or overall survival rates of the patients. Even though the role of single nucleotide polymorphisms of ATIC in chemotherapy-induced tumor necrosis has not been investigated yet, the ATIC 347C>G polymorphism may influence the levels of adenosine after MTX treatment, which may affect the histologic response of osteosarcoma. This relationship warrants validation in a larger, prospective cohort study.

Wang Z, Xiong F, Wang X, et al.
Nuclear receptor retinoid-related orphan receptor alpha promotes apoptosis but is reduced in human gastric cancer.
Oncotarget. 2017; 8(7):11105-11113 [PubMed] Free Access to Full Article Related Publications
Retinoid-related orphan receptor α (RORα) is a nuclear receptor, which regulates inflammation and immune responses, lipid metabolism and circadian rhythm. Although RORα suppresses breast tumor invasion, it is unknown whether RORα is dysregulated in gastric cancer leading to cellular survival. Therefore, we hypothesize that RORα is dysfunctional in gastric carcinoma and this causes decreased apoptosis in gastric cancer cells. To test this hypothesis, we employed human gastric cancer tissues with different stages to determine RORα expression, as well as in vitro human gastric cancer cells to determine how RORα is reduced during apoptosis. We found that the expression of RORα was reduced in gastric tissues with cancer, and this correlated with increased TNM stages. The mechanisms underlying RORα reduction is due to the reduced activation of AMP-activated protein kinase (AMPK), as a selective AMPK activator AICAR increased RORα activation and level in human gastric cancer cells. Furthermore, AICAR treatment increased RORα recruitment on the promoters of tumor suppressor genes (i.e., FBXM7, SEMA3F and p21) leading to apoptosis in human gastric cancer cells. Taken together, RORα reduction occurs in gastric cancer leading to the survival of tumor cells, which is attenuated by AMPK. Therefore, both RORα and AMPK are potential targets for the intervention and therapy in gastric carcinoma.

Morishita M, Kawamoto T, Hara H, et al.
AICAR induces mitochondrial apoptosis in human osteosarcoma cells through an AMPK-dependent pathway.
Int J Oncol. 2017; 50(1):23-30 [PubMed] Free Access to Full Article Related Publications
The AMP-activated protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) modulates cellular energy metabolism, and promotes mitochondrial proliferation and apoptosis. Previous studies have shown that AICAR has anticancer effects in various cancers, however the roles of AMPK and/or the effects of AICAR on osteosarcoma have not been reported. In the present study, we evaluated the effects of AICAR on tumor growth and mitochondrial apoptosis in human osteosarcoma both in vitro and in vivo. For in vitro experiments, two human osteosarcoma cell lines, MG63 and KHOS, were treated with AICAR, and the effects of AICAR on cell growth and mitochondrial apoptosis were assessed by WST assays, TUNEL staining, and immunoblot analyses. In vivo, human osteosarcoma-bearing mice were treated with AICAR, and the mitochondrial proliferation and apoptotic activity in treated tumors were assessed. In vitro experiments revealed that AICAR activated AMPK, inhibited cell growth, and induced mitochondrial apoptosis in both osteosarcoma cell lines. In vivo, AICAR significantly reduced osteosarcoma growth without apparent body weight loss and AICAR increased both mitochondrial proliferation and apoptotic activity in treated tumor tissues. AICAR showed anticancer effects in osteosarcoma cells through an AMPK-dependent peroxisome proliferator‑activated receptor-γ coactivator-1α (PGC-1α)/mitochondrial transcription factor A (TFAM)/mitochondrial pathway. The findings in this study strongly suggest that AICAR could be considered as a potent therapeutic agent for the treatment of human osteosarcoma.

Kopsiaftis S, Sullivan KL, Garg I, et al.
AMPKα2 Regulates Bladder Cancer Growth through SKP2-Mediated Degradation of p27.
Mol Cancer Res. 2016; 14(12):1182-1194 [PubMed] Free Access to Full Article Related Publications
AMP-activated protein kinase (AMPK) is the central metabolic regulator of the cell and controls energy consumption based upon nutrient availability. Due to its role in energy regulation, AMPK has been implicated as a barrier for cancer progression and is suppressed in multiple cancers. To examine whether AMPK regulates bladder cancer cell growth, HTB2 and HT1376 bladder cells were treated with an AMPK activator, 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR). AICAR treatment reduced proliferation and induced the expression of p27
IMPLICATIONS: These results highlight the contribution of AMPKα2 as a mechanism for controlling bladder cancer growth by regulating proliferation through mTOR suppression and induction of p27 protein levels, thus indicating how AMPKα2 loss may contribute to tumorigenesis. Mol Cancer Res; 14(12); 1182-94. ©2016 AACR.

Park SY, Lee HR, Lee WS, et al.
Cilostazol Modulates Autophagic Degradation of β-Amyloid Peptide via SIRT1-Coupled LKB1/AMPKα Signaling in Neuronal Cells.
PLoS One. 2016; 11(8):e0160620 [PubMed] Free Access to Full Article Related Publications
A neuroprotective role of autophagy mediates the degradation of β-amyloid peptide (Aβ) in Alzheimer's disease (AD). The previous study showed cilostazol modulates autophagy by increasing beclin1, Atg5 and LC3-II expressions, and depletes intracellular Aβ accumulation. This study elucidated the mechanisms through which cilostazol modulates the autophagic degradation of Aβ in neurons. In N2a cells, cilostazol (10-30 μM), significantly increased the expression of P-AMPKα (Thr 172) and downstream P-ACC (acetyl-CoA carboxylase) (Ser 79) as did resveratrol (SIRT1 activator), or AICAR (AMPK activator), which were blocked by KT5720, compound C (AMPK inhibitor), or sirtinol. Furthermore, phosphorylated-mTOR (Ser 2448) and phosphorylated-P70S6K (Thr 389) expressions were suppressed, and LC3-II levels were elevated in association with decreased P62/Sqstm1 by cilostazol. Cilostazol increased cathepsin B activity and decreased p62/SQSTM 1, consequently decreased accumulation of Aβ1-42 in the activated N2aSwe cells, and these results were blocked by sirtinol, compound C and bafilomycin A1 (autophagosome blocker), suggesting enhanced autophagosome formation by cilostazol. In SIRT1 gene-silenced N2a cells, cilostazol failed to increase the expressions of P-LKB1 (Ser 428) and P-AMPKα, which contrasted with its effect in negative control cells transfected with scrambled siRNA duplex. Further, N2a cells transfected with expression vectors encoding pcDNA SIRT1 showed increased P-AMPKα expression, which mimicked the effect of cilostazol in N2a cells; suggesting cilostazol-stimulated expressions of P-LKB1 and P-AMPKα were SIRT1-dependent. Unlike their effects in N2a cells, in HeLa cells, which lack LKB1, cilostazol and resveratrol did not elevate SIRT1 or P-AMPKα expression, indicating cilostazol and resveratrol-stimulated expressions of SIRT1 and P-AMPKα are LKB1-dependent. In conclusion, cilostazol upregulates autophagy by activating SIRT1-coupled P-LKB1/P-AMPKα and inhibiting mTOR activation, thereby decreasing Aβ accumulation.

Tsujimoto S, Yanagimachi M, Tanoshima R, et al.
Influence of ADORA2A gene polymorphism on leukoencephalopathy risk in MTX-treated pediatric patients affected by hematological malignancies.
Pediatr Blood Cancer. 2016; 63(11):1983-9 [PubMed] Related Publications
BACKGROUND: Methotrexate (MTX) can lead to neurotoxicity and asymptomatic leukoencephalopathy. However, the mechanism of MTX-related leukoencephalopathy is obscure. MTX and its metabolites inhibit 5-aminoimidazole-4-carboxamide ribonucleotide formiltransferase (ATIC) and promote adenosine release. Recently, it has been reported that adenosine and its receptor are related to certain central nervous system diseases. We investigated whether adenosine pathway gene polymorphisms and clinical factors were related to MTX-related leukoencephalopathy in pediatric patients affected by hematological malignancies.
PROCEDURE: Fifty-six Japanese childhood acute lymphoblastic leukemia or lymphoma patients were investigated. Patients were evaluated by magnetic resonance imaging of the brain before maintenance therapy or stem cell transplantation. Gene polymorphisms within the adenosine pathway (ATIC, adenosine A2A receptor [ADORA2A]) and the MTX pathway (methylenetetrahydrofolate reductase [MTHFR] and ABCB1) were genotyped using TaqMan assays. Clinical data were collected by accessing the medical records. MTX-related leukoencephalopathy was evaluated by a pediatric neurologist.
RESULTS: Twenty-one (37%) of 56 patients developed MTX-related leukoencephalopathy. Four of 21 patients developed clinical neurotoxicity. The minor allele CC genotype of rs2298383 (ADORA2A) was associated with MTX-related leukoencephalopathy (P = 0.010, odds ratio = 5.81, 95% confidence interval 1.50-22.50). High cumulative dose of systemic MTX was associated with MTX-related leukoencephalopathy after adjusting for sex, ADORA2A polymorphism, and prolonged high MTX concentration (P = 0.042, odds ratio = 1.18, 95% confidence interval 1.01-1.37).
CONCLUSIONS: ADORA2A rs2298383 and high cumulative dose of systemic MTX administration were significantly associated with MTX-related leukoencephalopathy. Our results indicate that pharmacological intervention within the adenosine pathway may be both a treatment and preventative option for MTX-related leukoencephalopathy.

Ducker GS, Chen L, Morscher RJ, et al.
Reversal of Cytosolic One-Carbon Flux Compensates for Loss of the Mitochondrial Folate Pathway.
Cell Metab. 2016; 23(6):1140-1153 [PubMed] Free Access to Full Article Related Publications
One-carbon (1C) units for purine and thymidine synthesis can be generated from serine by cytosolic or mitochondrial folate metabolism. The mitochondrial 1C pathway is consistently overexpressed in cancer. Here, we show that most but not all proliferating mammalian cell lines use the mitochondrial pathway as the default for making 1C units. Clustered regularly interspaced short palindromic repeats (CRISPR)-mediated mitochondrial pathway knockout activates cytosolic 1C-unit production. This reversal in cytosolic flux is triggered by depletion of a single metabolite, 10-formyl-tetrahydrofolate (10-formyl-THF), and enables rapid cell growth in nutrient-replete conditions. Loss of the mitochondrial pathway, however, renders cells dependent on extracellular serine to make 1C units and on extracellular glycine to make glutathione. HCT-116 colon cancer xenografts lacking mitochondrial 1C pathway activity generate the 1C units required for growth by cytosolic serine catabolism. Loss of both pathways precludes xenograft formation. Thus, either mitochondrial or cytosolic 1C metabolism can support tumorigenesis, with the mitochondrial pathway required in nutrient-poor conditions.

Li L, Hong HH, Chen SP, et al.
Activation of AMPK/MnSOD signaling mediates anti-apoptotic effect of hepatitis B virus in hepatoma cells.
World J Gastroenterol. 2016; 22(17):4345-53 [PubMed] Free Access to Full Article Related Publications
AIM: To investigate the anti-apoptotic capability of the hepatitis B virus (HBV) in the HepG2 hepatoma cell line and the underlying mechanisms.
METHODS: Cell viability and apoptosis were measured by MTT assay and flow cytometry, respectively. Targeted knockdown of manganese superoxide dismutase (MnSOD), AMP-activated protein kinase (AMPK) and hepatitis B virus X protein (HBx) genes as well as AMPK agonist AICAR and antagonist compound C were employed to determine the correlations of expression of these genes.
RESULTS: HBV markedly protected the hepatoma cells from growth suppression and cell death in the condition of serum deprivation. A decrease of superoxide anion production accompanied with an increase of MnSOD expression and activity was found in HepG2.215 cells. Moreover, AMPK activation contributed to the up-regulation of MnSOD. HBx protein was identified to induce the expression of AMPK and MnSOD.
CONCLUSION: Our results suggest that HBV suppresses mitochondrial superoxide level and exerts an anti-apoptotic effect by activating AMPK/MnSOD signaling pathway, which may provide a novel pharmacological strategy to prevent HCC.

Cheng F, He M, Jung JU, et al.
Suppression of Kaposi's Sarcoma-Associated Herpesvirus Infection and Replication by 5'-AMP-Activated Protein Kinase.
J Virol. 2016; 90(14):6515-6525 [PubMed] Free Access to Full Article Related Publications
UNLABELLED: The host intracellular antiviral restriction factors inhibit viral infection and replication. The 5'-AMP-activated protein kinase (AMPK) is a cellular energy sensor regulating metabolic homeostasis. Activated AMPK inhibits the replication of numerous RNA viruses but enhances the entry of vaccinia virus. However, the role of AMPK in herpesvirus infection is unclear. In this study, we showed that the constitutive AMPK activity restricted Kaposi's sarcoma-associated herpesvirus (KSHV) lytic replication in primary human umbilical vein endothelial cells while KSHV infection did not markedly affect the endogenous AMPK activity. Knockdown of the AMPKα1 considerably enhanced the expression of viral lytic genes and the production of infectious virions, while overexpression of a constitutively active AMPK had the opposite effects. Accordingly, an AMPK inhibitor, compound C, augmented viral lytic gene expressions and virion productions but an AMPK agonist, 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), suppressed both. Furthermore, a common diabetes drug, metformin, which carries an AMPK-agonistic activity, drastically inhibited the expression of viral lytic genes and the production of infectious virions, suggesting the use of metformin as a therapeutic agent for KSHV infection and replication. Together, these results identify the host AMPK as a KSHV restriction factor that can serve as a potential therapeutic target.
IMPORTANCE: Host cells encode specific proteins to restrict viral infection and replication. Kaposi's sarcoma-associated herpesvirus (KSHV) is a human tumor virus associated with several cancers. In this study, we have identified 5'-AMP-activated protein kinase (AMPK), a cellular energy sensor, as a restriction factor of KSHV lytic replication during primary infection. Activation of AMPK suppresses, while inhibition of AMPK enhances, KSHV lytic replication by regulating the expression of viral genes. AICAR and metformin, both of which are AMPK agonists currently used in clinics for the treatment of conditions associated with metabolic disorders, inhibit KSHV lytic replication. Thus, our work has identified AMPK as a potential therapeutic target and AICAR and metformin as potential therapeutic agents for KSHV-associated cancers.

Shen C, Ka SO, Kim SJ, et al.
Metformin and AICAR regulate NANOG expression via the JNK pathway in HepG2 cells independently of AMPK.
Tumour Biol. 2016; 37(8):11199-208 [PubMed] Related Publications
NANOG, a marker of stemness, impacts tumor progression and therapeutic resistance in cancer cells. In human hepatocellular carcinoma (HCC), upregulation of NANOG is associated with metastasis and a low survival rate, while its downregulation results in a lower colony formation rate and enhanced chemosensitivity. Metformin, an agent widely used for diabetes treatment, and AICAR, another AMP-activated protein kinase (AMPK) activator, have been reported to inhibit the growth of several types of cancer. Although inhibitory effects of metformin on NANOG in pancreatic cancer cells and of AICAR in mouse embryonic stem cells have been described, the underlying molecular mechanisms remain uncertain in HCC. In this study, we used the HepG2 cell line and found that metformin/AICAR downregulated NANOG expression with decreased cell viability and enhanced chemosensitivity to 5-fluorouracil (5-FU). Moreover, metformin/AICAR inhibited c-Jun N-terminal kinase (JNK) activity, and blockade of either the JNK MAPK pathway or knockdown of JNK1 gene expression reduced NANOG levels. The upregulation of NANOG and phospho-JNK by basic fibroblast growth factor (bFGF) was abrogated by metformin/AICAR. Additionally, although transient upregulation of NANOG within 2 h of treatment with metformin/AICAR was concordant with both JNK and AMPK activation, increased NANOG expression with activation of JNK was also observed following AMPK inhibition with compound C. Taken together, our data suggest that metformin/AICAR regulate NANOG expression via the JNK MAPK pathway in HepG2 cells independently of AMPK, and that this JNK/NANOG signaling pathway may offer new therapeutic strategies for the treatment of HCC.

Fodor T, Szántó M, Abdul-Rahman O, et al.
Combined Treatment of MCF-7 Cells with AICAR and Methotrexate, Arrests Cell Cycle and Reverses Warburg Metabolism through AMP-Activated Protein Kinase (AMPK) and FOXO1.
PLoS One. 2016; 11(2):e0150232 [PubMed] Free Access to Full Article Related Publications
Cancer cells are characterized by metabolic alterations, namely, depressed mitochondrial oxidation, enhanced glycolysis and pentose phosphate shunt flux to support rapid cell growth, which is called the Warburg effect. In our study we assessed the metabolic consequences of a joint treatment of MCF-7 breast cancer cells with AICAR, an inducer of AMP-activated kinase (AMPK) jointly with methotrexate (MTX), a folate-analog antimetabolite that blunts de novo nucleotide synthesis. MCF7 cells, a model of breast cancer cells, were resistant to the individual application of AICAR or MTX, however combined treatment of AICAR and MTX reduced cell proliferation. Prolonged joint application of AICAR and MTX induced AMPK and consequently enhanced mitochondrial oxidation and reduced the rate of glycolysis. These metabolic changes suggest an anti-Warburg rearrangement of metabolism that led to the block of the G1/S and the G2/M transition slowing down cell cycle. The slowdown of cell proliferation was abolished when mitotropic transcription factors, PGC-1α, PGC-1β or FOXO1 were silenced. In human breast cancers higher expression of AMPKα and FOXO1 extended survival. AICAR and MTX exerts similar additive antiproliferative effect on other breast cancer cell lines, such as SKBR and 4T1 cells, too. Our data not only underline the importance of Warburg metabolism in breast cancer cells but nominate the AICAR+MTX combination as a potential cytostatic regime blunting Warburg metabolism. Furthermore, we suggest the targeting of AMPK and FOXO1 to combat breast cancer.

Zhang Y, Xu F, Liang H, et al.
Exenatide inhibits the growth of endometrial cancer Ishikawa xenografts in nude mice.
Oncol Rep. 2016; 35(3):1340-8 [PubMed] Related Publications
Studies have showed that diabetes is one of the high risk factors of endometrial cancer; however, no reports describe the anti- or pro-cancer effect of a new kind of anti-diabetes drug, glucagon-like peptide-1 receptor agonist exenatide (exendin-4), on endometrial cancer. To investigate whether exenatide promotes or inhibits the growth of endometrial cancer, we used the subcutaneous human endometrial cancer cell Ishikawa xenografts in nude mouse model, and divided them into control group and exenatide-treated group. The tumor growth rate in exenatide group was slower than that in control group, and the apoptosis rate of exenatide group was higher than that in control group. In vitro, exendin-4 also attenuated Ishikawa cell viability and clone formation rate, but promoted cell apoptosis. There was an increase of phosphorylated-AMPK protein, a decrease of phosphorylated-mTOR protein both in vivo and in vitro after exenatide or exendin-4 treatment. Moreover, when treated with exendin-4 plus AICAR, an AMPK activator, cell apoptosis increased with higher ratio of phosphorylayed-AMPK/AMPK, lower ratio of phosphorylated-mTOR/mTOR and higher expression of cleaved caspase-3 than those in exendin-4 alone group, and the results were the opposite when treated with exendin-4 plus compound C, an AMPK inhibitor. Our results suggest that exenatide could attenuate the growth of endometrial cancer Ishikawa xenografts in nude mice, and AMPK may be the target of the mechanism.

Wu Y, Qi Y, Liu H, et al.
AMPK activator AICAR promotes 5-FU-induced apoptosis in gastric cancer cells.
Mol Cell Biochem. 2016; 411(1-2):299-305 [PubMed] Related Publications
The aim of the present study was to determine the effect of AICAR, an AMPK activator, on apoptosis in gastric carcinoma cells (SGC-7901) with or without 5-fluorouracil (5-FU). SGC-7901 cells were treated with AICAR (0.2-5 mM, for 24-48 h) with or without 5-FU. Cell viability was determined using MTT assay, while apoptosis were measured through the evaluation of active caspase-3 activity and DNA fragmentation. Real-time PCR was employed to determine the expression of tumor suppressor and multi-drug resistant (mdr1) gene. Cleaved caspase-3 and phosphorylated AMPK (p-AMPK) were measured by Western blot. AICAR significant reduced cellular viability but increased apoptosis in a time- and dose-dependent manner, which is associated with an increase in p-AMPK levels. Importantly, AICAR enhanced the sensitivity to 5-FU-induced reduction of cellular viability and increased apoptosis in SGC-7901 cells. Furthermore, AICAR increased tumor suppressor genes [F-box and WD repeat domain containing 7 (FBXW7), semaphorin III/F (SEMA3F), and p21(Cip1) (p21)] but reduced mdr1 expression. Finally, p-AMPK levels were reduced in 5-FU-resistant gastric cancer cells compared to human immortalized gastric epithelial cell line and 5-FU-sensitive gastric cancer cells. AICAR not only induces apoptosis alone but also enhances pro-apoptotic effect of 5-FU in SGC-7901 cells, which lays an experimental foundation to develop AICAR as a chemotherapeutic sensitizer against gastric cancer.

Kim JH, Lee JO, Kim N, et al.
Paclitaxel suppresses the viability of breast tumor MCF7 cells through the regulation of EF1α and FOXO3a by AMPK signaling.
Int J Oncol. 2015; 47(5):1874-80 [PubMed] Related Publications
Paclitaxel (Taxol), a potent drug of natural origin isolated from the bark of the Pacific yew, is widely used for treating ovarian, lung and breast cancers. Currently, there is little information regarding the specific mechanism underlying the anticancer activity of paclitaxel. In the present study, we found that 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR), a well-known activator of adenosine monophosphate (AMP)-activated protein kinase (AMPK), downregulated the protein and mRNA levels of elongation factor 1 α (EF1α) in breast cancer MCF7 cells. Paclitaxel increased the phosphorylation of AMPK and also downregulated the expression of EF1α in MCF7 cells. In addition, paclitaxel increased the expression, as well as the phosphorylation of forkhead box O3a (FOXO3a). Phosphorylation of FOXO3a was suppressed in the presence of compound C, a specific AMPK inhibitor, suggesting the involvement of AMPK in paclitaxel-induced FOXO3a phosphorylation. The induction and phosphorylation of FOXO3a by paclitaxel were not observed in EF1α and AMPK knockdown cells. Co-treatment with AICAR resulted in increased susceptibility of cancer cells to paclitaxel-induced suppression of their viability and further enhanced paclitaxel-induced FOXO3a phosphorylation. These results suggest that the antitumor effects of paclitaxel in breast cancer are mediated by activation of the AMPK/EF1α/FOXO3a signaling pathway.

Gollavilli PN, Kanugula AK, Koyyada R, et al.
AMPK inhibits MTDH expression via GSK3β and SIRT1 activation: potential role in triple negative breast cancer cell proliferation.
FEBS J. 2015; 282(20):3971-85 [PubMed] Related Publications
Recent studies have highlighted the involvement of metadherin (MTDH), an oncogenic protein, in promoting cancer progression, metastasis and chemoresistance in many cancers including mammary carcinomas. However, the molecular regulation of MTDH is still not completely understood. In this study we document that AMP activated protein kinase (AMPK) activation-induced anti-proliferative effects are, in part, mediated by inhibiting MTDH expression in MDA-MB-231 and BT-549 triple negative breast cancer (TNBC) cells. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMPK activator, caused growth arrest, inhibition of migration and invasion of TNBC cells. Intriguingly, AICAR or metformin treatment resulted in significant downregulation of MTDH expression via inhibiting c-Myc expression. In contrast, treatment of cells with compound C, an inhibitor of AMPK, increased both c-Myc and MTDH expressions in TNBC cells. Also, AMPK activation caused increased glycogen synthase kinase 3β (GSK3β) activity by inhibiting the inactive phosphorylation at Ser9, on the one hand, and activation of sirtuin1 (SIRT1) by inhibiting Ser47 phosphorylation, as evidenced by deacetylation of p53, on the other hand. Moreover, AMPK-induced GSK3β and SIRT1 activities were found to be responsible for inhibiting c-Myc-mediated upregulation of MTDH, as LiCl (an inhibitor of GSK3β) and EX-527 (an inhibitor of SIRT1) reversed AICAR-mediated downregulation of c-Myc and MTDH expressions. Similar results were observed with siSIRT1 treatment. Furthermore, AICAR and EX-527 treatments caused increased cell death under MTDH-depleted conditions. Finally, we uncovered a novel regulation of MTDH expression and showed that AMPK activation by inducing GSK3β and SIRT1 downregulates MTDH expression via inhibiting c-Myc in TNBC cells.

Montraveta A, Xargay-Torrent S, Rosich L, et al.
Bcl-2high mantle cell lymphoma cells are sensitized to acadesine with ABT-199.
Oncotarget. 2015; 6(25):21159-72 [PubMed] Free Access to Full Article Related Publications
Acadesine is a nucleoside analogue with known activity against B-cell malignancies. Herein, we showed that in mantle cell lymphoma (MCL) cells acadesine induced caspase-dependent apoptosis through turning on the mitochondrial apoptotic machinery. At the molecular level, the compound triggered the activation of the AMPK pathway, consequently modulating known downstream targets, such as mTOR and the cell motility-related vasodilator-stimulated phosphoprotein (VASP). VASP phosphorylation by acadesine was concomitant with a blockade of CXCL12-induced migration. The inhibition of the mTOR cascade by acadesine, committed MCL cells to enter in apoptosis by a translational downregulation of the antiapoptotic Mcl-1 protein. In contrast, Bcl-2 protein levels were unaffected by acadesine and MCL samples expressing high levels of Bcl-2 tended to have a reduced response to the drug. Targeting Bcl-2 with the selective BH3-mimetic agent ABT-199 sensitized Bcl-2high MCL cells to acadesine. This effect was validated in vivo, where the combination of both agents displayed a more marked inhibition of tumor outgrowth than each drug alone. These findings support the notions that antiapoptotic proteins of the Bcl-2 family regulate MCL cell sensitivity to acadesine and that the combination of this agent with Bcl-2 inhibitors might be an interesting therapeutic option to treat MCL patients.

Tong X, Kono T, Evans-Molina C
Nitric oxide stress and activation of AMP-activated protein kinase impair β-cell sarcoendoplasmic reticulum calcium ATPase 2b activity and protein stability.
Cell Death Dis. 2015; 6:e1790 [PubMed] Free Access to Full Article Related Publications
The sarcoendoplasmic reticulum Ca(2+) ATPase 2b (SERCA2b) pump maintains a steep Ca(2+) concentration gradient between the cytosol and ER lumen in the pancreatic β-cell, and the integrity of this gradient has a central role in regulated insulin production and secretion, maintenance of ER function and β-cell survival. We have previously demonstrated loss of β-cell SERCA2b expression under diabetic conditions. To define the mechanisms underlying this, INS-1 cells and rat islets were treated with the proinflammatory cytokine interleukin-1β (IL-1β) combined with or without cycloheximide or actinomycin D. IL-1β treatment led to increased inducible nitric oxide synthase (iNOS) gene and protein expression, which occurred concurrently with the activation of AMP-activated protein kinase (AMPK). IL-1β led to decreased SERCA2b mRNA and protein expression, whereas time-course experiments revealed a reduction in protein half-life with no change in mRNA stability. Moreover, SERCA2b protein but not mRNA levels were rescued by treatment with the NOS inhibitor l-NMMA (NG-monomethyl L-arginine), whereas the NO donor SNAP (S-nitroso-N-acetyl-D,L-penicillamine) and the AMPK activator AICAR (5-aminoimidazole-4-carboxamide ribonucleotide) recapitulated the effects of IL-1β on SERCA2b protein stability. Similarly, IL-1β-induced reductions in SERCA2b expression were rescued by pharmacological inhibition of AMPK with compound C or by transduction of a dominant-negative form of AMPK, whereas β-cell death was prevented in parallel. Finally, to determine a functional relationship between NO and AMPK signaling and SERCA2b activity, fura-2/AM (fura-2-acetoxymethylester) Ca(2+) imaging experiments were performed in INS-1 cells. Consistent with observed changes in SERCA2b expression, IL-1β, SNAP and AICAR increased cytosolic Ca(2+) and decreased ER Ca(2+) levels, suggesting congruent modulation of SERCA activity under these conditions. In aggregate, these results show that SERCA2b protein stability is decreased under inflammatory conditions through NO- and AMPK-dependent pathways and provide novel insight into pathways leading to altered β-cell calcium homeostasis and reduced β-cell survival in diabetes.

Chen ZT, Zhao W, Qu S, et al.
PARP-1 promotes autophagy via the AMPK/mTOR pathway in CNE-2 human nasopharyngeal carcinoma cells following ionizing radiation, while inhibition of autophagy contributes to the radiation sensitization of CNE-2 cells.
Mol Med Rep. 2015; 12(2):1868-76 [PubMed] Free Access to Full Article Related Publications
It was previously reported that poly-(adenosine diphosphate-ribose) polymerase-1 (PARP-1) regulated ionizing radiation (IR)-induced autophagy in CNE-2 human nasopharyngeal carcinoma cells. The present study aimed to investigate whether PARP-1-mediated IR-induced autophagy occurred via activation of the liver kinase B1 (LKB1)/adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway in CNE-2 cells. In addition, the effect of PARP-1 and AMPK inhibition on the radiation sensitization of CNE-2 cells was investigated. CNE-2 cells were treated with 10 Gy IR in the presence or absence of the AMPK activator 5-amino-1-β-D-ribofuranosyl-1H-imid-azole-4-carboxamide (AICAR). In addition, IR-treated CNE-2 cells were transfected with lentivirus-delivered small-hairpin RNA or treated with the AMPK inhibitor Compound C. Western blot analysis was used to assess the protein expression of PARP-1, phosphorylated (p)-AMPK, microtubule-associated protein 1 light chain 3 (LC3)-II and p-P70S6K. Cell viability and clone formation assays were performed to determine the effect of PARP-1 silencing and AMPK inhibition on the radiation sensitization of CNE-2 cells. The results showed that IR promoted PARP-1, p-AMPK and LC3-II protein expression as well as decreased p-P70S6K expression compared with that of the untreated cells. In addition, AICAR increased the expression of p-AMPK and LC3-II as well as decreased p-P70S6K expression compared with that of the IR-only group; however, AICAR did not increase PARP-1 expression. Furthermore, PARP-1 gene silencing decreased the expression of PARP-1, p-AMPK and LC3-II as well as increased p-P70S6K expression. Compound C decreased p-AMPK and LC3-Ⅱ expression as well as increased p-P70S6K expression; however, Compound C did not increase PARP-1 expression. Western blot analysis detected limited expression of p-LKB1 in all treatment groups. Cell viability and clone formation assays revealed that PARP-1 or AMPK inhibition reduced the proliferation of CNE-2 cells following IR. In conclusion, the present study demonstrated that PARP-1 promoted autophagy via the AMPK/mTOR pathway; in addition, PARP-1 or AMPK inhibition contributed to the radiation sensitization of CNE-2 cells following IR. However, it remains to be elucidated whether PARP-1 is an upstream mediator of the LKB1 pathway in CNE‑2 cells following IR.

Woo HI, Kim JA, Jung HA, et al.
Correlation of genetic polymorphisms with clinical outcomes in pemetrexed-treated advanced lung adenocarcinoma patients.
Pharmacogenomics. 2015; 16(4):383-91 [PubMed] Related Publications
AIM: Pemetrexed is a commonly used chemotherapeutic agent for lung adenocarcinoma patients. We investigated the impact of the genetic polymorphisms on the therapeutic efficacy of pemetrexed in lung adenocarcinoma patients.
MATERIALS & METHODS: We performed genotying of 51 polymorphisms of 13 genes in 243 lung adenocarcinoma patients treated with pemetrexed as a single agent for second or more line of therapy.
RESULTS: Total 12 polymorphisms in six genes were showed statistical significances in univariate analysis. After a false-discovery rate correction, the associations between GGH rs16930092 (p = 0.034) and rs10464903 (p = 0.034), and progression-free survival (PFS) were still conserved. Two polymorphisms in ATIC and GGH genes were associated with therapeutic efficacy in multivariate analysis: ATIC rs12995526 for tumor response (p = 0.014) and for overall survival (p = 0.006), and GGH rs16930092 (p = 0.009) for PFS.
CONCLUSION: This study shows that polymorphisms on genes related to the metabolic pathway of pemetrexed, especially, ATIC and GGH genes, would have a therapeutic implication in pemetrexed-treated patients with lung adenocarcinoma. Original submitted 10 May 2013; Revision submitted 27 June 2014.

Chen H, Wang JP, Santen RJ, Yue W
Adenosine monophosphate activated protein kinase (AMPK), a mediator of estradiol-induced apoptosis in long-term estrogen deprived breast cancer cells.
Apoptosis. 2015; 20(6):821-30 [PubMed] Related Publications
Estrogens stimulate growth of hormone-dependent breast cancer but paradoxically induce tumor regress under certain circumstances. We have shown that long-term estrogen deprivation (LTED) enhances the sensitivity of hormone dependent breast cancer cells to estradiol (E2) so that physiological concentrations of estradiol induce apoptosis in these cells. E2-induced apoptosis involve both intrinsic and extrinsic pathways but precise mechanisms remain unclear. We found that exposure of LTED MCF-7 cells to E2 activated AMP activated protein kinase (AMPK). In contrast, E2 inhibited AMPK activation in wild type MCF-7 cells where E2 prevents apoptosis. As a result of AMPK activation, the transcriptional activity of FoxO3, a downstream factor of AMPK, was up-regulated in E2 treatment of LTED. Increased activity of FoxO3 was demonstrated by up-regulation of three FoxO3 target genes, Bim, Fas ligand (FasL), and Gadd45α. Among them, Bim and FasL mediate intrinsic and extrinsic apoptosis respectively and Gadd45α causes cell cycle arrest at the G2/M phase. To further confirm the role of AMPK in apoptosis, we used AMPK activator AICAR in wild type MCF-7 cells and examined apoptosis, proliferation and expression of Bim, FasL, and Gadd45α. The effects of AICAR on these parameters recapitulated those observed in E2-treated LTED cells. Activation of AMPK by AICAR also increased expression of Bax in MCF-7 cells and its localization to mitochondria, which is a required process for apoptosis. These results reveal that AMPK is an important factor mediating E2-induced apoptosis in LTED cells, which is implicative of therapeutic potential for relapsing breast cancer after hormone therapy.

Wairagu PM, Phan AN, Kim MK, et al.
Insulin priming effect on estradiol-induced breast cancer metabolism and growth.
Cancer Biol Ther. 2015; 16(3):484-92 [PubMed] Free Access to Full Article Related Publications
Diabetes is a risk factor for breast cancer development and is associated with poor prognosis for breast cancer patients. However, the molecular and biochemical mechanisms underlying the association between diabetes and breast cancer have not been fully elucidated. Here, we investigated estradiol response in MCF-7 breast cancer cells with or without chronic exposure to insulin. We found that insulin priming is necessary and specific for estradiol-induced cancer cell growth, and induces anaplerotic shunting of glucose into macromolecule biosynthesis in the estradiol treated cells. Treatment with ERK or Akt specific inhibitors, U0126 or LY294002, respectively, suppressed estradiol-induced growth. Interestingly, molecular analysis revealed that estradiol treatment markedly increases expression of cyclin A and B, and decreases p21 and p27 in the insulin-primed cells. In addition, estradiol treatment activated metabolic genes in pentose phosphate (PPP) and serine biosynthesis pathways in the insulin-primed cells while insulin priming decreased metabolic gene expression associated with glucose catabolism in the breast cancer cells. Finally, we found that anti-diabetic drug metformin and AMPK ligand AICAR, but not thiazolidinediones (TZDs), specifically suppress the estradiol-induced cellular growth in the insulin-primed cells. These findings suggest that estrogen receptor (ER) activation under chronic hyperinsulinemic condition increases breast cancer growth through the modulation of cell cycle and apoptotic factors and nutrient metabolism, and further provide a mechanistic evidence for the clinical benefit of metformin use for ER-positive breast cancer patients with diabetes.

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