Research IndicatorsGraph generated 16 March 2017 using data from PubMed using criteria.
Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic. Tag cloud generated 16 March, 2017 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).
OMIM, Johns Hopkin University
Referenced article focusing on the relationship between phenotype and genotype.
International Cancer Genome Consortium.
Summary of gene and mutations by cancer type from ICGC
Cancer Genome Anatomy Project, NCI
COSMIC, Sanger Institute
Somatic mutation information and related details
GEO Profiles, NCBI
Search the gene expression profiles from curated DataSets in the Gene Expression Omnibus (GEO) repository.
Latest Publications: PPARGC1A (cancer-related)
Zhang S, Liu X, Liu J, et al.PGC-1 alpha interacts with microRNA-217 to functionally regulate breast cancer cell proliferation.
Biomed Pharmacother. 2017; 85:541-548 [PubMed
] Related Publications
BACKGROUND: In this study, we explored the functional mechanism of PPARg co-activator 1-alpha (PGC-1α) in regulating miR-217-mediated breast cancer development in vitro.
METHODS: Dual-luciferase activity assay was applied to examine the binding of miR-217 on PGC-1α gene. Breast cancer cell lines, MCF-7 and MDA-MB-231 were infected by lentivirus to constitutively downregulate miR-217. Its regulation on PGC-1α expression was investigated by qRT-PCR and western blot. PGC-1α gene was subsequently downregulated by siRNA in miR-217-downregulated breast cancer cells to examine its effect on cancer proliferation and cell-cycle progression. In addition, another downstream target gene of miR-217, DACH1, was further downregulated in breast cancer cells to investigate the functional association of PGC-1α and DACH1 in miR-217-mediated breast cancer regulation.
RESULTS: PGC-1α gene was directly bound by human miR-217. Downregulation of miR-217 in MCF-7 and MDA-MB-231 cells increased PGC-1α production at both mRNA and protein levels. SiRNA-mediated PGC-1α downregulation reversed the inhibition of miR-217-downregulaiton on breast cancer proliferation and cell-cycle progression. Moreover, siRNA-mediated DACH1 downregulation further reversed miR-217-downregulaiton induced inhibition on cancer proliferation and cell-cycle progression in PGC-1α downregulated MCF-7 and MDA-MB-231 cells.
CONCLUSION: MiR-217 is the upstream regulator of PGC-1α in breast cancer regulation in vitro, possibly independent of DACH1 signaling pathway.
Melanoma is the deadliest form of commonly encountered skin cancer because of its rapid progression towards metastasis. Although metabolic reprogramming is tightly associated with tumour progression, the effect of metabolic regulatory circuits on metastatic processes is poorly understood. PGC1α is a transcriptional coactivator that promotes mitochondrial biogenesis, protects against oxidative stress and reprograms melanoma metabolism to influence drug sensitivity and survival. Here, we provide data indicating that PGC1α suppresses melanoma metastasis, acting through a pathway distinct from that of its bioenergetic functions. Elevated PGC1α expression inversely correlates with vertical growth in human melanoma specimens. PGC1α silencing makes poorly metastatic melanoma cells highly invasive and, conversely, PGC1α reconstitution suppresses metastasis. Within populations of melanoma cells, there is a marked heterogeneity in PGC1α levels, which predicts their inherent high or low metastatic capacity. Mechanistically, PGC1α directly increases transcription of ID2, which in turn binds to and inactivates the transcription factor TCF4. Inactive TCF4 causes downregulation of metastasis-related genes, including integrins that are known to influence invasion and metastasis. Inhibition of BRAF(V600E) using vemurafenib, independently of its cytostatic effects, suppresses metastasis by acting on the PGC1α-ID2-TCF4-integrin axis. Together, our findings reveal that PGC1α maintains mitochondrial energetic metabolism and suppresses metastasis through direct regulation of parallel acting transcriptional programs. Consequently, components of these circuits define new therapeutic opportunities that may help to curb melanoma metastasis.
Kopp TI, Jensen DM, Ravn-Haren G, et al.Alcohol-related breast cancer in postmenopausal women - effect of CYP19A1, PPARG and PPARGC1A polymorphisms on female sex-hormone levels and interaction with alcohol consumption and NSAID usage in a nested case-control study and a randomised controlled trial.
BMC Cancer. 2016; 16:283 [PubMed
] Free Access to Full Article Related Publications
BACKGROUND: Alcohol consumption is associated with increased risk of breast cancer (BC), and the underlying mechanism is thought to be sex-hormone driven. In vitro and observational studies suggest a mechanism involving peroxisome proliferator-activated receptor gamma (PPARγ) in a complex with peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) and interaction with aromatase (encoded by CYP19A1). Use of non-steroidal anti-inflammatory drugs (NSAID) may also affect circulating sex-hormone levels by modifying PPARγ activity.
METHODS: In the present study we assessed whether genetic variation in CYP19A1 is associated with risk of BC in a case-control study group nested within the Danish "Diet, Cancer and Health" cohort (ncases = 687 and ncontrols = 687) and searched for gene-gene interaction between CYP19A1 and PPARGC1A, and CYP19A1 and PPARG, and gene-alcohol and gene-NSAID interactions. Association between the CYP19A1 polymorphisms and hormone levels was also examined among 339 non-HRT users. Incidence rate ratios were calculated based on Cox' proportional hazards model. Furthermore, we performed a pilot randomised controlled trial to determine the effect of the PPARG Pro(12)Ala polymorphism and the PPARγ stimulator Ibuprofen on sex-hormone levels following alcohol intake in postmenopausal women (n = 25) using linear regression.
RESULTS: Genetic variations in CYP19A1 were associated with hormone levels (estrone: P rs11070844 = 0.009, estrone sulphate: P rs11070844 = 0.01, P rs749292 = 0.004, P rs1062033 = 0.007 and P rs10519297 = 0.03, and sex hormone-binding globulin (SHBG): P rs3751591 = 0.03) and interacted with alcohol intake in relation to hormone levels (estrone sulphate: P interaction/rs2008691 = 0.02 and P interaction/rs1062033= 0.03, and SHBG: P interaction/rs11070844 = 0.03). CYP19A1/rs3751591 was both associated with SHBG levels (P = 0.03) and with risk of BC (Incidence Rate Ratio = 2.12; 95 % Confidence Interval: 1.02-4.43) such that homozygous variant allele carriers had increased levels of serum SHBG and were at increased risk of BC. Acute intake of alcohol decreased blood estrone (P = <0.0001), estrone sulphate (P = <0.0001), and SHBG (P = 0.009) levels, whereas Ibuprofen intake and PPARG Pro(12)Ala genotype had no effect on hormone levels.
CONCLUSIONS: Our results suggest that genetically determined variation in CYP19A1 is associated with differences in sex hormone levels. However, the genetically determined differences in sex hormone levels were not convincingly associated with BC risk. The results therefore indicate that the genetically determined variation in CYP19A1 contributes little to BC risk and to alcohol-mediated BC risk.
TRIAL REGISTRATION: NCT02463383, June 3, 2015.
Imaging studies in animals and in humans have indicated that the oxygenation and nutritional status of solid tumors is dynamic. Furthermore, the extremely low level of glucose within tumors, while reflecting its rapid uptake and metabolism, also suggests that cancer cells must rely on other energy sources in some circumstances. Here, we find that some breast cancer cells can switch to utilizing lactate as a primary source of energy, allowing them to survive glucose deprivation for extended periods, and that this activity confers resistance to PI3K/mTOR inhibitors. The nuclear receptor, estrogen-related receptor alpha (ERRα), was shown to regulate the expression of genes required for lactate utilization, and isotopomer analysis revealed that genetic or pharmacological inhibition of ERRα activity compromised lactate oxidation. Importantly, ERRα antagonists increased the in vitro and in vivo efficacy of PI3K/mTOR inhibitors, highlighting the potential clinical utility of this drug combination.
Breast cancer is the worldwide leading cause of cancer mortality in women. The majority of deaths from breast cancer arise from metastasis of local tumors. Cancer cells support their rapid proliferation by diverting metabolites into anabolic pathways, but during cancer metastasis, the proliferative program of invasive cancer cells is suspended for a migratory phenotype. In this study, we demonstrated that both mature forms of miRNA-485, miR-485-3p and miR-485-5p were involved in regulating mitochondrial respiration, cell migration and cell invasion in breast cancer cells by directly targeting and inhibiting the expression of PGC-1α. Specifically, the expression levels of both miR-485-3p and miR-485-5p were decreased in breast cancer tissues. Overexpression of miR-485-3p and miR-485-5p suppressed mitochondrial respiration and potential for cell migration and invasion in vitro, and also inhibited spontaneous metastasis of breast cancer cells in vivo. The suppression of mitochondrial respiration and cell invasion could be partially relieved by restoration of PGC-1α expression.
Audet-Walsh É, Papadopoli DJ, Gravel SP, et al.The PGC-1α/ERRα Axis Represses One-Carbon Metabolism and Promotes Sensitivity to Anti-folate Therapy in Breast Cancer.
Cell Rep. 2016; 14(4):920-31 [PubMed
] Related Publications
Reprogramming of cellular metabolism plays a central role in fueling malignant transformation, and AMPK and the PGC-1α/ERRα axis are key regulators of this process. The intersection of gene-expression and binding-event datasets for breast cancer cells shows that activation of AMPK significantly increases the expression of PGC-1α/ERRα and promotes the binding of ERRα to its cognate sites. Unexpectedly, the data also reveal that ERRα, in concert with PGC-1α, negatively regulates the expression of several one-carbon metabolism genes, resulting in substantial perturbations in purine biosynthesis. This PGC-1α/ERRα-mediated repression of one-carbon metabolism promotes the sensitivity of breast cancer cells and tumors to the anti-folate drug methotrexate. These data implicate the PGC-1α/ERRα axis as a core regulatory node of folate cycle metabolism and further suggest that activators of AMPK could be used to modulate this pathway in cancer.
Impairment of the autophagy-lysosome pathway is implicated with the changes in α-synuclein and mitochondrial dysfunction observed in Parkinson's disease (PD). Damaged mitochondria accumulate PINK1, which then recruits parkin, resulting in ubiquitination of mitochondrial proteins. These can then be bound by the autophagic proteins p62/SQSTM1 and LC3, resulting in degradation of mitochondria by mitophagy. Mutations in PINK1 and parkin genes are a cause of familial PD. We found a significant increase in the expression of p62/SQSTM1 mRNA and protein following mitophagy induction in human neuroblastoma SH-SY5Y cells. p62 protein not only accumulated on mitochondria, but was also greatly increased in the cytosol. Increased p62/SQSMT1 expression was prevented in PINK1 knock-down cells, suggesting increased p62 expression was a consequence of mitophagy induction. The transcription factors Nrf2 and TFEB, which play roles in mitochondrial and lysosomal biogenesis, respectively, can regulate p62/SQSMT1. We report that both Nrf2 and TFEB translocate to the nucleus following mitophagy induction and that the increase in p62 mRNA levels was significantly impaired in cells with Nrf2 or TFEB knockdown. TFEB translocation also increased expression of itself and lysosomal proteins such as glucocerebrosidase and cathepsin D following mitophagy induction. We also report that cells with increased TFEB protein have significantly higher PGC-1α mRNA levels, a regulator of mitochondrial biogenesis, resulting in increased mitochondrial content. Our data suggests that TFEB is activated following mitophagy to maintain autophagy-lysosome pathway and mitochondrial biogenesis. Therefore, strategies to increase TFEB may improve both the clearance of α-synuclein and mitochondrial dysfunction in PD. Damaged mitochondria are degraded by the autophagy-lysosome pathway and is termed mitophagy. Following mitophagy induction, the transcription factors Nrf2 and TFEB translocate to the nucleus, inducing the transcription of genes encoding for autophagic proteins such as p62, as well as lysosomal and mitochondrial proteins. We propose that these events maintain autophagic flux, replenish lysosomes and replace mitochondria.
The EglN2/PHD1 prolyl hydroxylase is an important oxygen sensor contributing to breast tumorigenesis. Emerging studies suggest that there is functional cross talk between oxygen sensing and mitochondrial function, both of which play an essential role for sustained tumor growth. However, the potential link between EglN2 and mitochondrial function remains largely undefined. Here, we show that EglN2 depletion decreases mitochondrial respiration in breast cancer under normoxia and hypoxia, which correlates with decreased mitochondrial DNA in a HIF1/2α-independent manner. Integrative analyses of gene expression profile and genomewide binding of EglN2 under hypoxic conditions reveal nuclear respiratory factor 1 (NRF1) motif enrichment in EglN2-activated genes, suggesting NRF1 as an EglN2 binding partner. Mechanistically, by forming an activator complex with PGC1α and NRF1 on chromatin, EglN2 promotes the transcription of ferridoxin reductase (FDXR) and maintains mitochondrial function. In addition, FDXR, as one of effectors for EglN2, contributes to breast tumorigenesis in vitro and in vivo. Our findings suggest that EglN2 regulates mitochondrial function in ERα-positive breast cancer.
Berger E, Vega N, Weiss-Gayet M, Géloën AGene Network Analysis of Glucose Linked Signaling Pathways and Their Role in Human Hepatocellular Carcinoma Cell Growth and Survival in HuH7 and HepG2 Cell Lines.
Biomed Res Int. 2015; 2015:821761 [PubMed
] Free Access to Full Article Related Publications
Cancer progression may be affected by metabolism. In this study, we aimed to analyze the effect of glucose on the proliferation and/or survival of human hepatocellular carcinoma (HCC) cells. Human gene datasets regulated by glucose were compared to gene datasets either dysregulated in HCC or regulated by other signaling pathways. Significant numbers of common genes suggested putative involvement in transcriptional regulations by glucose. Real-time proliferation assays using high (4.5 g/L) versus low (1 g/L) glucose on two human HCC cell lines and specific inhibitors of selected pathways were used for experimental validations. High glucose promoted HuH7 cell proliferation but not that of HepG2 cell line. Gene network analyses suggest that gene transcription by glucose could be mediated at 92% through ChREBP in HepG2 cells, compared to 40% in either other human cells or rodent healthy liver, with alteration of LKB1 (serine/threonine kinase 11) and NOX (NADPH oxidases) signaling pathways and loss of transcriptional regulation of PPARGC1A (peroxisome-proliferator activated receptors gamma coactivator 1) target genes by high glucose. Both PPARA and PPARGC1A regulate transcription of genes commonly regulated by glycolysis, by the antidiabetic agent metformin and by NOX, suggesting their major interplay in the control of HCC progression.
Sancho P, Burgos-Ramos E, Tavera A, et al.MYC/PGC-1α Balance Determines the Metabolic Phenotype and Plasticity of Pancreatic Cancer Stem Cells.
Cell Metab. 2015; 22(4):590-605 [PubMed
] Related Publications
The anti-diabetic drug metformin targets pancreatic cancer stem cells (CSCs), but not their differentiated progenies (non-CSCs), which may be related to distinct metabolic phenotypes. Here we conclusively demonstrate that while non-CSCs were highly glycolytic, CSCs were dependent on oxidative metabolism (OXPHOS) with very limited metabolic plasticity. Thus, mitochondrial inhibition, e.g., by metformin, translated into energy crisis and apoptosis. However, resistant CSC clones eventually emerged during treatment with metformin due to their intermediate glycolytic/respiratory phenotype. Mechanistically, suppression of MYC and subsequent increase of PGC-1α were identified as key determinants for the OXPHOS dependency of CSCs, which was abolished in resistant CSC clones. Intriguingly, no resistance was observed for the mitochondrial ROS inducer menadione and resistance could also be prevented/reversed for metformin by genetic/pharmacological inhibition of MYC. Thus, the specific metabolic features of pancreatic CSCs are amendable to therapeutic intervention and could provide the basis for developing more effective therapies to combat this lethal cancer.
Ranhotra HSThe orphan estrogen-related receptor alpha and metabolic regulation: new frontiers.
J Recept Signal Transduct Res. 2015; 35(6):565-8 [PubMed
] Related Publications
Metabolic homeostasis during long-term adaptation in animals is primarily achieved by controlling the expression of metabolic genes by a plethora of cellular transcription factors. The nuclear receptor (NR) superfamily in eukaryotes is an assembly of diverse receptors working as transcriptional regulators of multiple genes. The orphan estrogen-related receptor alpha (ERRα) is one such receptor of the NR superfamily with significant influence on numerous metabolic and other genes. Although it is presently unknown as to which endogenous hormones or ligands activate ERRα, nevertheless it regulates a host of genes whose products participate in various metabolic pathways. Studies over the years show new and interesting data that add to the growing knowledge on ERRα and metabolic regulation. For instance, novel findings indicate existence of mTOR/ERRα regulatory axis and also that ERRα control PGC-1α expression which potentially have significant impact on cellular metabolism. Data show that ERRα exerts its metabolic control by regulating the expression of SIRT5 that influences oxygen consumption and ATP generation. Moreover, ERRα has a role in creatine and lactate uptake in skeletal muscle which is important towards energy generation and contraction. This review is focused on the new insights gained into ERRα regulation of metabolism, networks and pathways that have important consequences in maintaining metabolic homeostasis including development of cancer.
Targeting glycolysis for cancer treatment has been investigated as a therapeutic method but has not offered a feasible chemotherapeutic strategy. Our aim was to examine whether AMP-activated protein kinase (AMPK), a conditional oncogene, rescues the energetic stress and cytotoxicity induced by 2-deoxyglucose (2-DG), a glycolytic inhibitor, and the related mechanisms. Luciferin/luciferase adenosine triphosphate (ATP) determination, Western analysis, qRT-PCR analyses, MTT growth assay, clonogenic assay, and statistical analysis were performed in this study. 2-DG decreased ATP levels and subsequently activated AMPK, which contribute to intracellular ATP recovery in MCF-7 cells thus exhibiting no apparent cytotoxicity. Compound C, an AMPK inhibitor, further potentiates 2-DG-induced decrease in ATP levels and inhibits their recovery. 2-DG, via AMPK activation, stimulated cAMP response element-binding protein (CREB) phosphorylation and activity and promoted nuclear peroxisome proliferator-activated receptor gamma coactivator-1-beta (PGC-1β) and estrogen-related receptor α (ERRα) protein expression, leading to augmented mitochondrial biogenesis and expression of fatty acid oxidation (FAO) genes including PPARα, MCAD, CPT1C, and ACO. This metabolic adaptation elicited by AMPK counteracts the ATP-depleting and cancer cell-killing effect of 2-DG. However, 2-DG in combination with AMPK antagonists or small interfering RNA caused a dramatic increase in cytotoxicity in MCF-7 but not in MCF-10A cells. Similarly, when combined with inhibition of CREB/PGC-1β/ERRα pathway, 2-DG saliently suppressed mitochondrial biogenesis and the expression of FAO genes, depleted ATP production, and enhanced cytotoxicity in cancer cells. Collectively, the combination of 2-DG and AMPK inhibition synergistically enhanced the cytotoxic potential in breast cancer cells with a relative nontoxicity to normal cells and may offer a promising, safe, and effective breast cancer therapeutic strategy.
Hamidian A, von Stedingk K, Munksgaard Thorén M, et al.Differential regulation of HIF-1α and HIF-2α in neuroblastoma: Estrogen-related receptor alpha (ERRα) regulates HIF2A transcription and correlates to poor outcome.
Biochem Biophys Res Commun. 2015; 461(3):560-7 [PubMed
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Hypoxia-inducible factors (HIFs) are differentially regulated in tumor cells. While the current paradigm supports post-translational regulation of the HIF-α subunits, we recently showed that hypoxic HIF-2α is also transcriptionally regulated via insulin-like growth factor (IGF)-II in the childhood tumor neuroblastoma. Here, we demonstrate that transcriptional regulation of HIF-2α seems to be restricted to neural cell-derived tumors, while HIF-1α is canonically regulated at the post-translational level uniformly across different tumor forms. Enhanced expression of HIF2A mRNA at hypoxia is due to de novo transcription rather than increased mRNA stability, and chemical stabilization of the HIF-α proteins at oxygen-rich conditions unexpectedly leads to increased HIF2A transcription. The enhanced HIF2A levels do not seem to be dependent on active HIF-1. Using a transcriptome array approach, we identified members of the Peroxisome proliferator-activated receptor gamma coactivator (PGC)/Estrogen-related receptor (ERR) complex families as potential regulators of HIF2A. Knockdown or inhibition of one of the members, ERRα, leads to decreased expression of HIF2A, and high expression of the ERRα gene ESRRA correlates with poor overall and progression-free survival in a clinical neuroblastoma material consisting of 88 tumors. Thus, targeting of ERRα and pathways regulating transcriptional HIF-2α are promising therapeutic avenues in neuroblastoma.
Vellinga TT, Borovski T, de Boer VC, et al.SIRT1/PGC1α-Dependent Increase in Oxidative Phosphorylation Supports Chemotherapy Resistance of Colon Cancer.
Clin Cancer Res. 2015; 21(12):2870-9 [PubMed
] Related Publications
PURPOSE: Chemotherapy treatment of metastatic colon cancer ultimately fails due to development of drug resistance. Identification of chemotherapy-induced changes in tumor biology may provide insight into drug resistance mechanisms.
EXPERIMENTAL DESIGN: We studied gene expression differences between groups of liver metastases that were exposed to preoperative chemotherapy or not. Multiple patient-derived colonosphere cultures were used to assess how chemotherapy alters energy metabolism by measuring mitochondrial biomass, oxygen consumption, and lactate production. Genetically manipulated colonosphere-initiated tumors were used to assess how altered energy metabolism affects chemotherapy efficacy.
RESULTS: Gene ontology and pathway enrichment analysis revealed significant upregulation of genes involved in oxidative phosphorylation (OXPHOS) and mitochondrial biogenesis in metastases that were exposed to chemotherapy. This suggested chemotherapy induces a shift in tumor metabolism from glycolysis towards OXPHOS. Indeed, chemotreatment of patient-derived colonosphere cultures resulted in an increase of mitochondrial biomass, increased expression of respiratory chain enzymes, and higher rates of oxygen consumption. This was mediated by the histone deacetylase sirtuin-1 (SIRT1) and its substrate, the transcriptional coactivator PGC1α. Knockdown of SIRT1 or PGC1α prevented chemotherapy-induced OXPHOS and significantly sensitized patient-derived colonospheres as well as tumor xenografts to chemotherapy.
CONCLUSIONS: Chemotherapy of colorectal tumors induces a SIRT1/PGC1α-dependent increase in OXPHOS that promotes tumor survival during treatment. This phenomenon is also observed in chemotherapy-exposed resected liver metastases, strongly suggesting that chemotherapy induces long-lasting changes in tumor metabolism that potentially interfere with drug efficacy. In conclusion, we propose a novel mechanism of chemotherapy resistance that may be clinically relevant and therapeutically exploitable.
PGC-1α, a major metabolic regulator of gluconeogenesis and lipogenesis, is strongly induced to coactivate Hepatitis B virus (HBV) gene expression in the liver of fasting mice. We found that 8-Br-cAMP and glucocorticoids synergistically induce PGC-1α and its downstream targets, including PEPCK and G6Pase. Also, HBV core promoter activity was synergistically enhanced by 8-Br-cAMP and glucocorticoids. Graptopetalum paraguayense (GP), a herbal medicine, is commonly used in Taiwan to treat liver disorders. Partially purified fraction of GP (named HH-F3) suppressed 8-Br-cAMP/glucocorticoid-induced G6Pase, PEPCK and PGC-1α expression and suppressed HBV core promoter activity. HH-F3 blocked HBV core promoter activity via inhibition of PGC-1α expression. Ectopically expressed PGC-1α rescued HH-F3-inhibited HBV surface antigen expression, HBV mRNA production, core protein levels, and HBV replication. HH-F3 also inhibited fatty acid synthase (FASN) expression and decreased lipid accumulation by down-regulating PGC-1α. Thus, HH-F3 can inhibit HBV replication, gluconeogenesis and lipogenesis by down-regulating PGC-1α. Our study indicates that targeting PGC-1α may be a therapeutic strategy for treatment of HBV infections. HH-F3 may have potential use for the treatment of chronic hepatitis B patients with associated metabolic syndrome.
Yu W, Cao D, Zhou H, et al.PGC-1α is responsible for survival of multiple myeloma cells under hyperglycemia and chemotherapy.
Oncol Rep. 2015; 33(4):2086-92 [PubMed
] Related Publications
The association between hyperglycemia and outcomes during chemotherapy has been reported in several tumors, including multiple myeloma (MM). However, the underlying mechanism of how hyperglycemia affects the survival of MM cells during chemotherapy remain to be elucidated. MM cells were cultured in 10 mM glucose with or without chemotherapeutic agents. Following treatment of MM cells with dexamethasone or bortezomib, an MTT assay was used to evaluate the toxicity of dexamethasone or bortezomib on cell proliferation, and changes of reactive oxygen species (ROS) level were detected by flow cytometry (FCM) analysis. Small interference RNA (siRNA) was applied to inhibit the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). Expressions of PGC-1α and antioxidant factors such as superoxide dismutase 2 (SOD‑2), glutathione peroxidase 1 (GPX-1), and catalase (CAT) were measured by RT-PCR prior to and following treatment. The results showed that the level of PGC-1α in MM cells cultured in high-glucose medium was upregulated prior to and following treatment of chemotherapeutic agents, and these cells showed less fold-change of ROS after insult of drugs, when compared to the control. Genes encoding antioxidant factors such as SOD-2 and CAT were also upregulated. Inhibition of PGC-1α enhanced the toxicity of antitumor agents, associated with reduced expression of antioxidant factors, and elevated level of ROS. The present findings suggested that hyperglycemia may influence the anticancer effect of chemotherapeutic agents in MM by upregulating the expression of PGC-1α and associated antioxidant factors. Inhibition of PGC-1α or control of hyperglycemia may be beneficial in improving the efficacy of chemotherapy in MM patients with diabetes.
Shin SW, Yun SH, Park ES, et al.Overexpression of PGC‑1α enhances cell proliferation and tumorigenesis of HEK293 cells through the upregulation of Sp1 and Acyl-CoA binding protein.
Int J Oncol. 2015; 46(3):1328-42 [PubMed
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Peroxisome proliferator-activated receptor γ coactivator-1α (PGC‑1α), a coactivator interacting with multiple transcription factors, regulates several metabolic processes. Although recent studies have focused on the role of PGC‑1α in cancer, the underlying molecular mechanism has not been clarified. Therefore, we evaluated the role of PGC‑1α in cell proliferation and tumorigenesis using human embryonic kidney (HEK)293 cells and colorectal cancer cells. We established stable HEK293 cell lines expressing PGC‑1α and examined cell proliferation, anchorage-independent growth, and oncogenic potential compared to parental HEK293 cells. To identify the molecular PGC‑1α targets for increased cell proliferation and tumorigenesis, the GeneFishing™ DEG (differentially expressed genes) screening system was used. Western blot analysis and immunofluorescence staining were performed for a regulated gene product to confirm the results. Forced expression of PGC‑1α in HEK293 cells promoted cell proliferation and anchorage-independent growth in soft agar. In addition, HEK293 cells that highly expressed PGC‑1α showed enhanced tumor formation when subcutaneously injected into the bilateral flanks of immunodeficient mice. The results of the GeneFishing DEG screening system identified one upregulated gene (Acyl-CoA binding protein; ACBP). Real-time RT-PCR, western blot analysis, and immunofluorescence staining showed that ACBP was markedly increased in HEK293 cells stably overexpressing PGC‑1α (PGC‑1α-HEK293 cells) compared to those expressing an empty vector. In PGC‑1α, ACBP, and specificity protein 1 (Sp1) siRNA knockdown experiments in PGC‑1α-HEK293 and SNU-C4 cells, we also observed inhibition of cell proliferation, reduced expression of antioxidant enzymes, and increased H2O2-induced reactive oxygen species production and apoptosis. These findings suggest that PGC‑1α may promote cell proliferation and tumorigenesis through upregulation of ACBP. We provide evidence that increased Sp1 expression might contribute to enhanced ACBP expression by PGC‑1α. The current results also suggest that PGC‑1α, whose expression is related to enhanced cell proliferation and tumorigenesis, may be a good candidate molecular target for cancer therapy.
Overexpression of SIRT1 is frequently observed in various types of cancers, suggesting its potential role in malignancies. However, the molecular basis of how SIRT1 is elevated in cancer is less understood. Here we show that cancer-related SIRT1 overexpression is due to evasion of Sirt1 mRNA from repression by a group of Sirt1-targeting microRNAs (miRNAs) that might be robustly silenced in cancer. Our comprehensive library-based screening and subsequent miRNA gene profiling revealed a housekeeping gene-like broad expression pattern and strong CpG island-association of the Sirt1-targeting miRNA genes. This suggests aberrant CpG DNA methylation as the mechanistic background for malignant SIRT1 elevation. Our work also provides an example where epigenetic mechanisms cause the group-wide regulation of miRNAs sharing a common key target.
Cao D, Jin L, Zhou H, et al.Inhibition of PGC-1α after chemotherapy-mediated insult confines multiple myeloma cell survival by affecting ROS accumulation.
Oncol Rep. 2015; 33(2):899-904 [PubMed
] Related Publications
Peroxisome proliferator‑activated receptor-γ coactivator-1α (PGC-1α) is a key regulator of reactive oxygen species (ROS). However, whether it has the same role in multiple myeloma (MM), especially after treatement with chemotherapy, remains unclear. After treating cells with bortezomib or dexamethasone, the expression of PGC-1α, superoxide dismutase 2 (SOD-2) and catalase (CAT) was examined by RT-PCR. PGC-1α expression was also analyzed by western blotting. Small‑interference RNA (siRNA) was applied to inhibit the expression of PGC-1α after chemotherapy. Changes of cellular ROS and apoptosis were detected by flow cytometric analysis. Cell proliferation was assessed by MTT assay. The expression of PGC-1α and SOD-2 following chemotherapy were upregulated, but accompanied by increased ROS. Following suppression of PGC-1α, ROS levels, as well as the pro-apoptotic effect of bortezomib were further increased. These findings suggested that PGC-1α regulates ROS in MM, and that inhibition of elevated PGC-1α following stimulation by chemotherapy leads to a higher level of ROS by downregulating antioxidant factors, eventually enhancing the antitumor effect of bortezomib.
OBJECTIVE: Aggregation of α-synuclein (α-syn) and α-syn cytotoxicity are hallmarks of sporadic and familial Parkinson disease (PD), with accumulating evidence that prefibrillar oligomers and protofibrils are the pathogenic species in PD and related synucleinopathies. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a key regulator of mitochondrial biogenesis and cellular energy metabolism, has recently been associated with the pathophysiology of PD. Despite extensive effort on studying the function of PGC-1α in mitochondria, no studies have addressed whether PGC-1α directly influences oligomerization of α-syn or whether α-syn oligomers impact PGC-1α expression.
MATERIALS AND METHODS: We tested whether pharmacological or genetic activation of PGC-1α or PGC-11α knockdown could modulate the oligomerization of α-syn in vitro by using an α-syn -fragment complementation assay.
RESULTS: In this study, we found that both PGC-1α reference gene (RG-PGC-1α) and the central nervous system (CNS)-specific PGC-1α (CNS-PGC-1α) are downregulated in human PD brain, in A30P α-syn transgenic animals, and in a cell culture model for α-syn oligomerization. Importantly, downregulation of both RG-PGC-1α and CNS-PGC-1α in cell culture or neurons from RG-PGC-1α-deficient mice leads to a strong induction of α-syn oligomerization and toxicity. In contrast, pharmacological activation or genetic overexpression of RG-PGC-1α reduced α-syn oligomerization and rescued α-syn-mediated toxicity.
INTERPRETATION: Based on our results, we propose that PGC-1α downregulation and α-syn oligomerization form a vicious circle, thereby influencing and/or potentiating each other. Our data indicate that restoration of PGC-1α is a promising approach for development of effective drugs for the treatment of PD and related synucleinopathies.
Tao L, Park JY, Lambert JDDifferential prooxidative effects of the green tea polyphenol, (-)-epigallocatechin-3-gallate, in normal and oral cancer cells are related to differences in sirtuin 3 signaling.
Mol Nutr Food Res. 2015; 59(2):203-11 [PubMed
] Related Publications
SCOPE: We have previously reported that the green tea catechin, (-)-epigallocatechin-3-gallate (EGCG), can induce oxidative stress in oral cancer cells but exerts antioxidant effects in normal cells. Here, we report that these differential prooxidative effects are associated with sirtuin 3 (SIRT3), an important mitochondrial redox modulator.
METHODS AND RESULTS: EGCG rapidly induced mitochondria-localized reactive oxygen species in human oral squamous carcinoma cells (SCC-25, SCC-9) and premalignant leukoplakia cells (MSK-Leuk1), but not in normal human gingival fibroblast cells (HGF-1). EGCG suppressed SIRT3 mRNA and protein expression, as well as, SIRT3 activity in SCC-25 cells, whereas it increased SIRT3 activity in HGF-1 cells. EGCG selectively decreased the nuclear localization of the estrogen-related receptor α (ERRα), the transcription factor regulating SIRT3 expression, in SCC-25 cells. This indicates that EGCG may regulate SIRT3 transcription in oral cancer cells via ERRα. EGCG also differentially modulated the mRNA expressions of SIRT3-associated downstream targets including glutathione peroxidase 1 and superoxide dismutase 2 in normal and oral cancer cells.
CONCLUSION: SIRT3 represents a novel potential target through which EGCG exerts differential prooxidant effects in cancer and normal cells. Our results provide new biomarkers to be further explored in animal studies.
Cancer cells can divert metabolites into anabolic pathways to support their rapid proliferation and to accumulate the cellular building blocks required for tumour growth. However, the specific bioenergetic profile of invasive and metastatic cancer cells is unknown. Here we report that migratory/invasive cancer cells specifically favour mitochondrial respiration and increased ATP production. Invasive cancer cells use the transcription coactivator peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PPARGC1A, also known as PGC-1α) to enhance oxidative phosphorylation, mitochondrial biogenesis and the oxygen consumption rate. Clinical analysis of human invasive breast cancers revealed a strong correlation between PGC-1α expression in invasive cancer cells and the formation of distant metastases. Silencing of PGC-1α in cancer cells suspended their invasive potential and attenuated metastasis without affecting proliferation, primary tumour growth or the epithelial-to-mesenchymal program. Inherent genetics of cancer cells can determine the transcriptome framework associated with invasion and metastasis, and mitochondrial biogenesis and respiration induced by PGC-1α are also essential for functional motility of cancer cells and metastasis.
The liver is a key metabolic organ that controls whole-body physiology in response to nutrient availability. Mammalian target of rapamycin (mTOR) is a nutrient-activated kinase and central controller of growth and metabolism that is negatively regulated by the tumor suppressor tuberous sclerosis complex 1 (TSC1). To investigate the role of hepatic mTOR complex 1 (mTORC1) in whole-body physiology, we generated liver-specific Tsc1 (L-Tsc1 KO) knockout mice. L-Tsc1 KO mice displayed reduced locomotor activity, body temperature, and hepatic triglyceride content in a rapamycin-sensitive manner. Ectopic activation of mTORC1 also caused depletion of hepatic and plasma glutamine, leading to peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α)-dependent fibroblast growth factor 21 (FGF21) expression in the liver. Injection of glutamine or knockdown of PGC-1α or FGF21 in the liver suppressed the behavioral and metabolic defects due to mTORC1 activation. Thus, mTORC1 in the liver controls whole-body physiology through PGC-1α and FGF21. Finally, mTORC1 signaling correlated with FGF21 expression in human liver tumors, suggesting that treatment of glutamine-addicted cancers with mTOR inhibitors might have beneficial effects at both the tumor and whole-body level.
Adiponectin is an adipocyte-secreted adipokine with pleiotropic actions. Clinical evidence has shown that serum adiponectin levels are increased and that adiponectin can protect pancreatic beta cells against apoptosis, which suggests that adiponectin may play an anti-apoptotic role in pancreatic cancer (PC). Here, we investigated the effects of adiponectin on PC development and elucidated the underlying molecular mechanisms. Adiponectin deficiency markedly attenuated pancreatic tumorigenesis in vivo. We found that adiponectin significantly inhibited the apoptosis of both human and mouse pancreatic cancer cells via adipoR1, but not adipoR2. Furthermore, adiponectin can increase AMP-activated protein kinase (AMPK) phosphorylation and NAD-dependent deacetylase sirtuin-1 (Sirt1) of PC cells. Knockdown of AMPK or Sirt1 can increase the apoptosis in PC cells. AMPK up-regulated Sirt1, and Sirt1 can inversely phosphorylate AMPK. Further studies have shown that Sirt1 can deacetylate peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), which can increase the expression levels of mitochondrial genes. Thus, adiponectin exerts potent anti-apoptotic effects on PC cells via the activation of AMPK/Sirt1/PGC1α signaling. Finally, adiponectin can elevate β-catenin levels. Taken together, these novel findings reveal an unconventional role of adiponectin in promoting pancreatic cancers, and suggest that the effects of adiponectin on tumorigenesis are highly tissue-dependent.
Chen Y, Wang Z, Xu M, et al.Nanosilver incurs an adaptive shunt of energy metabolism mode to glycolysis in tumor and nontumor cells.
ACS Nano. 2014; 8(6):5813-25 [PubMed
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Due to its significant antimicrobial properties, nanosilver (nAg) has been substantially used in a wide spectrum of areas. This has raised the concerns on the detrimental effects on environment and human health. Although numerous studies have documented nAg-mediated toxicity to cells or organisms, little attempt has been made to study the biological impacts of nAg on cells at nontoxic concentrations, namely, the distinct biological effects that can be separated from direct cytotoxicity. Here, we studied nAg-mediated effects on energy metabolism in cells under sublethal exposure. Treatment of nAg at nontoxic concentrations resulted in a decline of ATP synthesis and attenuation of respiratory chain function in nontumor HEK293T cells and tumor cells with differential respiration rate, including HepG2, HeLa, A498, and PC3 cells. Cellular energy homeostasis was switched from oxidative phosphorylation-based aerobic metabolism to anaerobic glycolysis, which is an adaption process to satisfy the energy demand for cell survival. Nanospheres with smaller size showed greater capability to alter cellular energy metabolism than those with larger size or nanoplates. Mechanistic investigation manifested that inhibition of PGC-1α by nAg was, at least partially, accountable for the transition from oxidative phosphorylation to glycolysis. Additionally, altered expression of a few energy metabolism-related genes (such as PFKFB3 and PDHA1) was also involved in the transition process. We further showed nAg-induced depolarization of mitochondrial membrane potential and reduction of respiratory chain complex activity. Together, our combined results uncovered the mechanisms by which nAg induced energy metabolism reprogramming in both tumor and nontumor cells under sublethal dosage.
Neill T, Torres A, Buraschi S, et al.Decorin induces mitophagy in breast carcinoma cells via peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and mitostatin.
J Biol Chem. 2014; 289(8):4952-68 [PubMed
] Free Access to Full Article Related Publications
Tumor cell mitochondria are key biosynthetic hubs that provide macromolecules for cancer progression and angiogenesis. Soluble decorin protein core, hereafter referred to as decorin, potently attenuated mitochondrial respiratory complexes and mitochondrial DNA (mtDNA) in MDA-MB-231 breast carcinoma cells. We found a rapid and dynamic interplay between peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and the decorin-induced tumor suppressor gene, mitostatin. This interaction stabilized mitostatin mRNA with concurrent accumulation of mitostatin protein. In contrast, siRNA-mediated abrogation of PGC-1α-blocked decorin-evoked stabilization of mitostatin. Mechanistically, PGC-1α bound MITOSTATIN mRNA to achieve rapid stabilization. These processes were orchestrated by the decorin/Met axis, as blocking the Met-tyrosine kinase or knockdown of Met abrogated these responses. Furthermore, depletion of mitostatin blocked decorin- or rapamycin-evoked mitophagy, increased vascular endothelial growth factor A (VEGFA) production, and compromised decorin-evoked VEGFA suppression. Collectively, our findings underscore the complexity of PGC-1α-mediated mitochondrial homeostasis and establish mitostatin as a key regulator of tumor cell mitophagy and angiostasis.
Cao D, Zhou H, Zhao J, et al.PGC-1α integrates glucose metabolism and angiogenesis in multiple myeloma cells by regulating VEGF and GLUT-4.
Oncol Rep. 2014; 31(3):1205-10 [PubMed
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Human peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) is a key coactivator in the regulation of gene transcriptional activity in normal tissues. However, it is not clear whether it is involved in the angiogenesis and metabolism of multiple myeloma (MM). The aim of the present study was to investigate the role of PGC-1α in MM. Small interfering RNA (siRNA) was used to inhibit PGC-1α expression in RPMI-8226 cells. An endothelial cell migration assay was performed using transwell chambers and the expression of PGC-1α, estrogen-related receptor-α (ERR-α), vascular endothelial growth factor (VEGF) and glucose transporter-4 (GLUT-4) was tested by reverse transcription-polymerase chain reaction (RT-PCR). The protein expression of PGC-1α, ERR-α and GLUT-4 was assayed by western blot analysis. Lastly, RPMI-8226 cell proliferation was evaluated using CCK-8 assay. VEGF and GLUT-4 mRNA levels were decreased in cells treated with siRNA targeting PGC-1α, as was the level of GLUT-4 protein. Endothelial cell migration was significantly reduced when these cells were cultured with culture medium from RPMI-8226 cells treated with siPGC-1α. The proliferation rates at 24 and 48 h were suppressed by PGC-1α inhibition. Our results showed that inhibition of PGC-1α suppresses cell proliferation probably by downregulation of VEGF and GLUT-4. The present study suggests that PGC-1α integrates angiogenesis and glucose metabolism in myeloma through regulation of VEGF and GLUT-4.
Cancer cells tend to utilize aerobic glycolysis even under normoxic conditions, commonly called the "Warburg effect." Aerobic glycolysis often directly correlates with malignancy, but its purpose, if any, in metastasis remains unclear. When wild-type KISS1 metastasis suppressor is expressed, aerobic glycolysis decreases and oxidative phosphorylation predominates. However, when KISS1 is missing the secretion signal peptide (ΔSS), invasion and metastasis are no longer suppressed and cells continue to metabolize using aerobic glycolysis. KISS1-expressing cells have 30% to 50% more mitochondrial mass than ΔSS-expressing cells, which are accompanied by correspondingly increased mitochondrial gene expression and higher expression of PGC1α, a master coactivator that regulates mitochondrial mass and metabolism. PGC1α-mediated downstream pathways (i.e., fatty acid synthesis and β-oxidation) are differentially regulated by KISS1, apparently reliant upon direct KISS1 interaction with NRF1, a major transcription factor involved in mitochondrial biogenesis. Since the downstream effects could be reversed using short hairpin RNA to KISS1 or PGC1α, these data appear to directly connect changes in mitochondria mass, cellular glucose metabolism, and metastasis.
Hann SS, Chen J, Wang Z, et al.Targeting EP4 by curcumin through cross talks of AMP-dependent kinase alpha and p38 mitogen-activated protein kinase signaling: the role of PGC-1α and Sp1.
Cell Signal. 2013; 25(12):2566-74 [PubMed
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Head and neck cancer is one of the most morbid human malignancies with an overall poor prognosis and severely compromised quality of life. As a result, there is significant interest in developing adjuvant therapies to augment currently available treatment protocols. Curcumin has been found to possess anti-cancer activities via its effect on a variety of biological pathways. In this study, we showed that curcumin inhibits head and neck cancer cell growth through reduction of PGE2 receptor EP4 gene expression. Blockade of AMP-dependent kinase (AMPK), and p38 MAPK by either chemical inhibitors or siRNAs antagonized the inhibitory effect of curcumin on EP4 expression, which was reversed by metformin, an activator of AMPK. Curcumin induced PGC-1α protein that was blocked by compound C and SB239063. Silencing of PGC-1α reversed the effect of curcumin on EP4 protein. Overexpression of EP4 overcame the effect of curcumin on head and neck cancer cell growth. In addition, curcumin reduced Sp1 protein. Overexpression of Sp1 resisted the inhibitory effect of curcumin on EP4 promoter activity and protein expression. Interestingly, overexpression of PGC-1α further enhanced the inhibitory effect of curcumin on Sp1 protein expression that was blocked by SB239063. In conclusion, this study shows that curcumin inhibits EP4 gene expression dependent of AMPKα and p38 MAPK activation, this leads to reduction of Sp1 protein and binding to specific area in the EP4 gene promoter. The cross talks of AMPKα and p38 MAPK signaling, the kinase-mediated PGC-1α expression and reciprocity of PGC-1α and Sp1 enhance this process. This ultimately results in inhibition of head and neck cancer cell proliferation.
Li Y, He L, Zeng N, et al.Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) signaling regulates mitochondrial biogenesis and respiration via estrogen-related receptor α (ERRα).
J Biol Chem. 2013; 288(35):25007-24 [PubMed
] Free Access to Full Article Related Publications
Mitochondrial abnormalities are associated with cancer development, yet how oncogenic signals affect mitochondrial functions has not been fully understood. In this study, we investigate the relationship between mitochondrial alterations and PI3K/protein kinase B (AKT) signaling activation using hepatocytes and liver tissues as our experimental models. We show here that liver-specific deletion of Pten, which leads to activation of PI3K/AKT, is associated with elevated oxidative stress, increased mitochondrial mass, and augmented respiration accompanied by enhanced glycolysis. Consistent with these observations, estrogen-related receptor α (ERRα), an orphan nuclear receptor known for its role in mitochondrial biogenesis, is up-regulated in the absence of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Our pharmacological and genetic studies show that PI3K/AKT activity regulates the expression of ERRα and mitochondrial biogenesis/respiration. Furthermore, cAMP-response element-binding protein, as a downstream target of AKT, plays a role in the regulation of ERRα, independent of PKA signaling. ERRα regulates reactive oxygen species production, and ERRα knockdown attenuates proliferation and colony-forming potential in Pten-null hepatocytes. Finally, analysis of clinical datasets from liver tissues showed a negative correlation between expressions of ERRα and PTEN in patients with liver cancer. Therefore, this study has established a previously unrecognized link between a growth signal and mitochondrial metabolism.