Upregulation Of Lactate Dehydrogenase A Research Articles

Lactate dehydrogenase A inhibition prevents RANKL-induced osteoclastogenesis by reducing enhanced glycolysis

Osteoclasts are multinucleated, specializes bone-resorbing cells that are derived from the monocyte/macrophage lineage. Excessive resorbing activities of osteoclasts are involved in destructive bone diseases. The detailed mechanism of acidification at the bone adhesion surface during the bone resorption process of osteoclasts remains to be defined. During glycolysis, pyruvate proceeds to the tricarboxylic cycle under aerobic conditions and pyruvate is converted to lactate via lactate dehydrogenase A (LDHA) under anaerobic conditions. However, tumor cells produce ATP during aerobic glycolysis and large amounts of pyruvate are converted to lactate and H+ by LDHA. Lactate and H+ are excreted outside the cell, whereby they are involved in invasion of tumor cells due to the pH drop around the cell. In this study, we focused on aerobic glycolysis and investigated the production of lactate by LDHA in osteoclasts. Expression of LDHA and monocarboxylate transporter 4 (MCT4) was upregulated during osteoclast differentiation. Intracellular and extracellular lactate levels increased with upregulation of LDHA and MCT4, respectively. FX11 (an LDHA inhibitor) inhibited osteoclast differentiation and suppressed the bone-resorbing activity of osteoclasts. We propose that inhibition of LDHA may represent a novel therapeutic strategy for controlling excessive bone resorption in osteoporosis and rheumatoid arthritis.

Altered Peripheral Blood Gene Expression in Childhood Cancer Survivors With Anthracycline-Induced Cardiomyopathy - A COG-ALTE03N1 Report.

Background Anthracycline-induced cardiomyopathy is a leading cause of premature death in childhood cancer survivors, presenting a need to understand the underlying pathogenesis. We sought to examine differential blood-based mRNA expression profiles in anthracycline-exposed childhood cancer survivors with and without cardiomyopathy. Methods and Results We designed a matched case-control study (Children's Oncology Group-ALTE03N1) with mRNA sequencing on total RNA from peripheral blood in 40 anthracycline-exposed survivors with cardiomyopathy (cases) and 64 matched survivors without (controls). DESeq2 identified differentially expressed genes. Ingenuity Pathway Analyses (IPA) and Gene Set Enrichment Analyses determined the potential roles of altered genes in biological pathways. Functional validation was performed by gene knockout in human-induced pluripotent stem cell-derived cardiomyocytes using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) technology. Median age at primary cancer diagnosis for cases and controls was 8.2 and 9.7 years, respectively. Thirty-six differentially expressed genes with fold change ≥±2 were identified; 35 were upregulated. IPA identified "hepatic fibrosis" and "iron homeostasis" pathways to be significantly modulated by differentially expressed genes, including toxicology functions of myocardial infarction, cardiac damage, and cardiac dilation. Leading edge analysis from Gene Set Enrichment Analyses identified lactate dehydrogenase A (LDHA) and cluster of differentiation 36 (CD36) genes to be significantly upregulated in cases. Interleukin 1 receptor type 1, 2 (IL1R1, IL1R2), and matrix metalloproteinase 8, 9 (MMP8, MMP9) appeared in multiple canonical pathways. LDHA-knockout human-induced pluripotent stem cell-derived cardiomyocytes showed increased sensitivity to doxorubicin. Conclusions We identified differential mRNA expression profiles in peripheral blood of anthracycline-exposed childhood cancer survivors with and without cardiomyopathy. Upregulation of LDHA and CD36 genes suggests metabolic perturbations in a failing heart. Dysregulation of proinflammatory cytokine receptors IL1R1 and IL1R2 and matrix metalloproteinases, MMP8 and MMP9 indicates structural remodeling that accompanies the clinical manifestation of symptomatic cardiotoxicity.

Sirolimus increases the anti-cancer effect of Huai Er by regulating hypoxia inducible factor-1α-mediated glycolysis in hepatocellular carcinoma.

BACKGROUNDGlycolysis caused by hypoxia-induced abnormal activation of hypoxia inducible factor-1α (HIF-1α) in the immune microenvironment promotes the progression of hepatocellular carcinoma (HCC), leading to enhanced drug resistance in cancer cells. Therefore, altering the immunosuppressive microenvironment by imp-roving the hypoxic state is a new goal in improving cancer treatment.AIMTo analyse the role of HIF-1α, which is closely related to tumour proliferation, invasion, metastasis, and angiogenesis, in the proliferation and invasion of liver cancer, and to explore the HIF-1α pathway-mediated anti-cancer mechanism of sirolimus (SRL) combined with Huai Er.METHODSPrevious studies on HCC tissues identified the importance of HIF-1α, glucose transporter 1 (GLUT1), and lactate dehydrogenase A (LDHA) expression. In this study, HepG2 and Huh7 cell lines were treated, under hypoxic and normoxic conditions, with a combination of SRL and Huai Er. The effects on proliferation, invasion, cell cycle, and apoptosis were analysed. Proteomics and genomics techniques were used to analyze the HIF-1α-related signalling pathway during SRL combined with Huai Er treatment and its inhibition of the proliferation of HCC cells.RESULTSHigh levels of HIF-1α, LDHA, and GLUT-1 were found in poorly differentiated HCC, with lower patient survival rates. Hypoxia promoted the proliferation of HepG2 and Huh7 cells and weakened the apoptosis and cell cycle blocking effects of the SRL/Huai Er treatment. This was achieved by activation of HIF-1α and glycolysis in HCC, leading to the upregulation of LDHA, GLUT-1, Akt/mammalian target of rapamycin (mTOR), vascular endothelial growth factor (VEGF), and Forkhead box P3 and downregulation of phosphatase and tensin homolog deleted on chromosome ten (PTEN) and p27. The hypoxia-induced activation of HIF-1α showed the greatest attenuation in the SRL/Huai Er (S50 + H8) group compared to the drug treatments alone (P < 0.001). The S50 + H8 treatment significantly downregulated the expression of mTOR and HIF-1α, and significantly reduced the expression of VEGF mRNA. Meanwhile, the combined blocking of mTOR and HIF-1α enhanced the downregulation of Akt/mTOR, HIF-1α, LDHA, and GLUT-1 mRNA and resulted in the downregulation of PTEN, p27, and VEGF mRNA (P < 0.001).CONCLUSIONSRL increases the anti-cancer effect of Huai Er, which reduces the promotion of hypoxia-induced HIF-1α on the Warburg effect by inhibition of the PI3K/Akt/mTOR-HIF-1α and HIF-1α-PTEN signalling pathways in HCC.

LINC01128 facilitates the progression of pancreatic cancer through up-regulation of LDHA by targeting miR-561-5p

BackgroundLong non-coding RNAs (lncRNAs) regulate tumor development and metastasis in several types of cancers through various molecular mechanisms. However, the biological role of most lncRNAs in pancreatic cancer (PC) remains unclear. Here, we explored the expression, biological functions, and molecular mechanism of LINC01128 in PC.MethodsQuantitive reverse transcription PCR was used to detect the expression level of LINC01128 in PC tissues and different PC cell lines. A loss-of-function and gain-of-function experiment was used to explore the biological effects of LINC01128 on PC carcinogenesis in vitro and in vivo. Western blot analysis, subcellular fractionation experiment, luciferase reporter gene assay, and MS2-RNA immunoprecipitation experiment were used to study the potential molecular mechanism of LINC01128 during carcinogenesis.ResultsThe expression of LINC01128 was upregulated in PC tissues and cell lines, and overexpression of LINC01128 was significantly related to the poor prognosis of patients with PC. Furthermore, silencing LINC01128 significantly inhibited the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of PC cells in vitro and tumor growth in vivo, while LINC01128 overexpression promoted these processes. Further research showed that LINC01128 acted as a sponge for microRNA miR-561-5p, and lactate dehydrogenase A (LDHA) was the downstream target gene of miR-561-5p. It was also revealed that the expression of miR-561-5p in PC was decreased, and a negative correlation between miR-561-5p and LINC01128 was revealed. Based on rescue experiments, LDHA overexpression partially restored the inhibitory effect of LINC01128 knockdown on proliferation, migration, and invasion of PC cells.ConclusionsLINC01128 promotes the proliferation, migration, invasion, and EMT of PC by regulating the miR-561-5p/LDHA axis, suggesting LINC01128 may be a new prognostic marker and therapeutic target in PC.

CircLPAR3 knockdown suppresses esophageal squamous cell carcinoma cell oncogenic phenotypes and Warburg effect through miR-873-5p/LDHA axis.

Circular RNAs (circRNAs) have been identified to participate in regulating multiple malignancies. Herein, this study aimed to explore the clinical significance, biological function, and regulatory mechanisms of circRNA lysophosphatidic acid receptor 3 (circLPAR3) in esophageal squamous cell carcinoma (ESCC) cell malignant phenotypes and Warburg effect. The qRT-PCR and Western blot were used to detect the levels of genes and proteins. Glucose uptake and lactate production were detected to determine the Warburg effect. The effects of circLPAR3 on ESCC cell proliferation, apoptosis, and metastasis were evaluated by MTT, 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, wound healing, and transwell assays. The binding interaction between miR-873-5p and circLPAR3 or lactate dehydrogenase A (LDHA) was verified using dual-luciferase reporter and RIP assays. Xenograft mice models were established to conduct in vivo analysis. CircLPAR3 is a stable circRNA and was increased in ESCC tissues and cells. Functionally, circLPAR3 knockdown suppressed ESCC cell Warburg effect, proliferation, metastasis, and induced apoptosis in vitro, and impeded xenograft tumor growth and Warburg effect in ESCC mice models. Mechanistically, circLPAR3 served as a sponge for miR-873-5p, which targeted LDHA. Moreover, circLPAR3 could regulate LDHA expression by sponging miR-873-5p. Thereafter, rescue experiments suggested that miR-873-5p inhibition reversed the anticancer effects of circLPAR3 silencing on ESCC cells. Furthermore, miR-873-5p overexpression restrained ESCC cell Warburg effect and oncogenic phenotypes, which were abolished by LDHA up-regulation. CircLPAR3 knockdown suppressed ESCC cell growth, metastasis, and Warburg effect by miR-873-5p/LDHA axis, implying a promising molecular target for ESCC therapy.

Blocking circ-CNST suppresses malignant behaviors of osteosarcoma cells and inhibits glycolysis through circ-CNST-miR-578-LDHA/PDK1 ceRNA networks

BackgroundCircRNA CNST (circ-CNST) is a newly identified biomarker for prognosis of osteosarcoma (OS). However, its role in OS progression remains to be well documented.MethodsExpression of circ-CNST, microRNA (miR)-578, lactate dehydrogenase A (LDHA), and pyruvate dehydrogenase kinase 1 (PDK1) was detected by quantitative real-time polymerase chain reaction and Western blotting. The physical interaction was confirmed by dual-luciferase reporter assay. Cell behaviors and glycolysis were measured by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay, colony formation assay, flow cytometry, transwell assays, xenograft experiment, and commercial kits.ResultsCirc-CNST was upregulated in human OS tissues and cells, accompanied with downregulation of miR-578 and upregulation of LDHA and PDK1. There were negative correlations between miR-578 expression and circ-CNST or LDHA/PDK1 in OS tissues. Moreover, high circ-CNST/LDHA/PDK1 or low miR-578 might predict shorter overall survival, advanced TNM stages, and lymph node metastasis. Physically, miR-578 was targeted by circ-CNST, and miR-578 could target LDHA/PDK1. Functionally, blocking circ-CNST and restoring miR-578 enhanced apoptosis rate and suppressed cell proliferation, colony formation, migration, and invasion in 143B and U2OS cells, accompanied with decreased glucose consumption, lactate production, and adenosine triphosphate (ATP)/adenosine diphosphate (ADP) ratio. Furthermore, in vivo growth of U2OS cells was retarded by silencing circ-CNST. Depletion of miR-578 could counteract the suppressive role of circ-CNST deficiency in 143B and U2OS cells, and restoring LDHA or PDK1 partially reversed the role of miR-578 inhibition as well.ConclusionCirc-CNST knockdown could antagonize malignant behaviors and glycolysis of OS cells by regulating miR-578-LDHA/PDK1 axes.

Lactate Dehydrogenase A as a Potential New Biomarker for Thyroid Cancer.

BackgroundSeveral cancers show increased levels of lactate dehydrogenase A (LDHA), which are associated with cancer progression. However, it remains unclear whether LDHA levels are associated with papillary thyroid cancer (PTC) aggressiveness or with the presence of the PTC prognostic marker, the BRAFV600E mutation. This study aimed to evaluate the potential of LDHA as a PTC prognostic marker.MethodsLDHA expression was examined in 83 PTC tissue specimens by immunohistochemistry. Human thyroid cell lines were genetically manipulated to overexpress BRAFV600E or were treated with a BRAF-specific short hairpin RNA (shBRAF), whose effects on LDHA expression were evaluated by Western blotting. Data from 465 PTC patients were obtained from The Cancer Genome Atlas (TCGA) database and analyzed to validate the in vitro results.ResultsLDHA was aberrantly overexpressed in PTC. Intense immunostaining for LDHA was observed in PTC specimens carrying mutated BRAF, whereas the intensity was less in wild-type BRAF samples. Overexpression of BRAFV600E resulted in LDHA upregulation, whereas treatment with shBRAF downregulated LDHA in human thyroid cell lines. Furthermore, LDHA mRNA expression was significantly elevated and associated with BRAFV600E expression in thyroid cancer tissues from TCGA database. Additionally, LDHA overexpression was found to be correlated with aggressive clinical features of PTC, such as lymph node metastases and advanced tumor stages.ConclusionLDHA overexpression is associated with the BRAFV600E mutation and an aggressive PTC behavior. Therefore, LDHA may serve as a biomarker and therapeutic target in PTC.

Lysine-222 succinylation reduces lysosomal degradation of lactate dehydrogenase a and is increased in gastric cancer

BackgroundLysine succinylation is an emerging posttranslational modification that has garnered increased attention recently, but its role in gastric cancer (GC) remains underexplored.MethodsProteomic quantification of lysine succinylation was performed in human GC tissues and adjacent normal tissues by mass spectrometry. The mRNA and protein levels of lactate dehydrogenase A (LDHA) in GC and adjacent normal tissues were analyzed by qRT-PCR and western blot, respectively. The expression of K222-succinylated LDHA was measured in GC tissue microarray by the K222 succinylation-specific antibody. The interaction between LDHA and sequestosome 1 (SQSTM1) was measured by co-immunoprecipitation (co-IP) and proximity ligation assay (PLA). The binding of carnitine palmitoyltransferase 1A (CPT1A) to LDHA was determined by co-IP. The effect of K222-succinylated LDHA on tumor growth and metastasis was evaluated by in vitro and in vivo experiments.ResultsAltogether, 503 lysine succinylation sites in 303 proteins were identified. Lactate dehydrogenase A (LDHA), the key enzyme in Warburg effect, was found highly succinylated at K222 in GC. Intriguingly, this modification did not affect LDHA ubiquitination, but reduced the binding of ubiquitinated LDHA to SQSTM1, thereby decreasing its lysosomal degradation. We demonstrated that CPT1A functions as a lysine succinyltransferase that interacts with and succinylates LDHA. Moreover, high K222-succinylation of LDHA was associated with poor prognosis in patients with GC. Finally, overexpression of a succinylation-mimic mutant of LDHA promoted cell proliferation, invasion, and migration.ConclusionsOur data revealed a novel lysosomal pathway of LDHA degradation, which is mediated by the binding of K63-ubiquitinated LDHA to SQSTM1. Strikingly, CPT1A succinylates LDHA on K222, which thereby reduces the binding and inhibits the degradation of LDHA, as well as promotes GC invasion and proliferation. This study thus uncovers a new role of lysine succinylation and the mechanism underlying LDHA upregulation in GC.

A Feedforward Mechanism for Epileptogenesis Regulated by Lactate Dehydrogenase A

Abstract INTRODUCTION Despite the ketogenic diet's successful use since the 1920s, epilepsy as a disease of energy metabolism is a novel concept. We previously established that seizures deplete neuronal energy stores and reprogram neurons from aerobic to glycolytic metabolic phenotype, marked by upregulation of lactate dehydrogenase A (LDHA). LDHA has recently been shown to play a role in neuronal membrane depolarization and epileptogenesis. We show here that LDHA upregulation through HIF1a may lead to seizure formation. METHODS Resected tissue from 11 epileptic patients were probed for LDHA expression. To study the electrophysiological consequences of LDHA, we used a mixed rat cortical cell culture model on a microelectrode array (MEA). Furthermore, we developed a novel murine model of chronic focal cortical epilepsy to establish HIF1a's role in mediating LDHA expression and seizure formation. Finally, we used a lentivirus vector to directly upregulate LDHA in neurons cultured on an MEA to measure neuronal bursting. RESULTS We found LDHA increased significantly in epileptic tissue versus nonepileptic tissue. Induction of seizure activity in cultured neurons with low magnesium resulted in increased LDHA and subsequently increased baseline bursting over 10 d. Inhibition of LDHA activity with stiripentol and isosafrole decreased the overall burst frequency. Cells that were induced to upregulate LDHA via DMOG, an upstream HIF1a potentiator, showed a significant increase in baseline bursting activity. Furthermore, placement of cobalt, a HIF1a stabilizer, into the frontal cortex of mice caused chronic seizures emanating from perilesion cortex which showed increased LDHA. Finally, direct LDHA upregulation resulted in increased bursting activity confirming that LDHA may lead to seizure formation. CONCLUSION Overall, our data show that LDHA, regulated by HIF1a, can contribute to seizure development. These data suggest a novel molecular mechanism for the pathogenesis of epilepsy where seizures cause LDHA upregulation which then further drives seizures, leading to a cycle of epileptogenesis.

A Combination of Human Embryonic Stem Cell-Derived Pancreatic Endoderm Transplant with LDHA-Repressing miRNA Can Attenuate High-Fat Diet Induced Type II Diabetes in Mice.

Type II diabetes mellitus (T2D) is a chronic metabolic disorder that results from defects in both insulin secretion and insulin action. The deficit and dysfunction of insulin secreting β-cell are signature symptom for T2D. Additionally, in pancreatic β-cell, a small group of genes which are abundantly expressed in most other tissues are highly selectively repressed. Lactate dehydrogenase A (LDHA) is one of such genes. Upregulation of LDHA is found in both human T2D and rodent T2D models. In this study, we identified a LDHA-suppressing microRNA (hsa-miR-590-3p) and used it together with human embryonic stem cell (hESC) derived pancreatic endoderm (PE) transplantation into a high-fat diet induced T2D mouse model. The procedure significantly improved glucose metabolism and other symptoms of T2D. Our findings support the potential T2D treatment using the combination of microRNA and hESC-differentiated PE cells.

O10.03 * PHYSIOLOGICAL AND BIOLOGICAL RESPONSES OF HUMAN GLIOBLASTOMAS TO BEVACIZUMAB TREATMENT ASSESSED BY METABOLOMIC FLUX ANALYSIS

We have in two different xenograft model systems of human glioblastoma (GBM) that reflect the genotype and phenotype of human GBMs, assessed using 13C6-glucose metabolomic flux analysis, how the tumors adapt to anti-vascular therapy (bevacizumab treatment). A detailed LC-MS analyses of 13C-labeled metabolites show that the tumors adapt to therapy by undergoing metabolomic re-programming events towards anaerobic respiration (glycolysis). This is characterized by an increased influx of 13C6-glucose into the tumors, leading increased levels of 13C-labeled lactate. Moreover, the LC-MS analyses show that bevacizumab treatment leads to reduced levels of metabolites associated with the tricarboxylic acid cycle (TCA cycle) as well as L-glutamine, indicating a reduced oxidative respiration and less ATP production from the TCA cycle. Depletion in glutathione levels was also observed, indicating that bevacizumab treatment causes oxidative stress in the tumors. Immunohistochemical analysis showed an up-regulation of lactate dehydrogenaseA (LDHA) in the bevacizumab treated tumor core as well as in single tumor cells infiltrating the brain indicating an acidification of the microenvironment that may promote invasion. These observations were further verified in a panel of 8 human GBM patients were paired biopsy samples were obtained before and after bevacizumab treatment. Finally, a detailed flow cytometric ploidy and phenotype marker expression of the tumors before and after bevacizumab treatment indicates that the changes observed represent an adaptive response to therapy and not clonal selection.

Lactate dehydrogenase A is a potential prognostic marker in clear cell renal cell carcinoma.

BackgroundOver 90% of cancer-related deaths in clear cell renal cell carcinoma (RCC) are caused by tumor relapse and metastasis. Thus, there is an urgent need for new molecular markers that can potentiate the efficacy of the current clinical-based models of prognosis assessment. The objective of this study is to evaluate the potential significance of lactate dehydrogenase A (LDHA), assessed by immunohistochemical staining, as a prognostic marker in clear cell renal cell carcinoma in relation to clinicopathological features and clinical outcome.MethodsWe assessed the expression of LDHA at the protein level, by immunohistochemistry, and correlated its expression with multiple clinicopathological features including tumor size, clinical stage, histological grade, disease-free and overall survival in 385 patients with primary clear cell renal cell carcinoma. We also correlated the LDHA expression with overall survival, at mRNA level, in an independent data set of 170 clear cell renal cell carcinoma cases from The Cancer Genome Atlas databases. Cox proportional hazards models adjusted for the potential clinicopathological factors were used to test for associations between the LDHA expression and both disease-free survival and overall survival.ResultsThere is statistically significant positive correlation between LDHA level of expression and tumor size, clinical stage and histological grade. Moreover, LDHA expression shows significantly inverse correlation with both disease-free survival and overall survival in patients with clear cell renal cell carcinoma. Our results are validated by examining LDHA expression, at the mRNA level, in the independent data set of clear cell renal cell carcinoma cases from The Cancer Genome Atlas databases which also shows that higher lactate dehydrogenase A expression is associated with significantly shorter overall survival.ConclusionOur results indicate that LDHA up-regulation can be a predictor of poor prognosis in clear cell renal cell carcinoma. Thus, it represents a potential prognostic biomarker that can boost the accuracy of other prognostic models in patients with clear cell renal cell carcinoma.

LDH-A Acetylation: Implication in Cancer

LDH-A Acetylation: Implication in Cancer

Abstract 5427: Increased glycolysis by 14-3-3ζ-mediated LDHA up-regulation contributes to transformation of early mammary epithelial cells.

Abstract The Warburg effect is a distinct cancer hallmark that shifts the metabolic pathway in cancer cells through elevated aerobic glycolysis for energy supply and biomass. However, the mechanism of early stage metabolic dysregulation still remains unclear. 14-3-3ζ was found to be over-expressed in the early stages of breast disease and cancer (Atypical ductal hyperplasia and Ductal carcinoma in situ) and in &amp;gt;40% of breast cancer patients, correlating with poor patient prognosis. We found that 14-3-3ζ over-expression in non-transformed human mammary epithelial cells (HMECs), MCF10A and MCF12A, positively correlated with changes in the cellular glycolytic activity (increased glucose uptake, increased lactate production and reduced oxygen consumption). Additionally, 14-3-3ζ over-expression in HMECs induced soft agar colony formation and disorganized acini in three dimensional (3D) culture. Interestingly, we identified that lactate dehydrogenase A (LDHA) was up-regulated in these 14-3-3ζ overexpressing HMECs. LDHA knockdown in 14-3-3ζ overexpressing cells reduced aerobic glycolysis, decreased soft agar colonies and partially rescued the abnormal acinar structures, indicating LDHA upregulation contributed to 14-3-3ζ-mediated aerobic glycolysis and early transformation. Taken together, our data provide new insight into metabolic deregulation during the early stages of breast cancer transformation. Citation Format: Chia-Chi Chang, Jia Xu, Hai Wang, Chenyu Zhang, Jian Zhang, Sumaiyah K. Rehman, Ping Li, Dihua Yu. Increased glycolysis by 14-3-3ζ-mediated LDHA up-regulation contributes to transformation of early mammary epithelial cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5427. doi:10.1158/1538-7445.AM2013-5427

Lysine-5 Acetylation Negatively Regulates Lactate Dehydrogenase A and Is Decreased in Pancreatic Cancer

Tumor cells commonly have increased glucose uptake and lactate accumulation. Lactate is produced from pyruvate by lactate dehydrogenase A (LDH-A), which is frequently overexpressed in tumor cells and is important for cell growth. Elevated transcription by c-Myc or HIF1α may contribute to increased LDH-A in some cancer types. Here, we show that LDH-A is acetylated at lysine 5 (K5) and that this acetylation inhibits LDH-A activity. Furthermore, the K5-acetylated LDH-A is recognized by the HSC70 chaperone and delivered to lysosomes for degradation. Replacement of endogenous LDH-A with an acetylation mimetic mutant decreases cell proliferation and migration. Importantly, K5 acetylation of LDH-A is reduced in human pancreatic cancers. Our study reveals a mechanism of LDH-A upregulation in pancreatic cancers.

Abstract 3208: Overcoming cancer therapeutic resistance by targeting dysregulated glucose metabolism

Abstract Heat shock transcription factor 1 (HSF1) is the master regulator of the heat shock responses in eukaryotes. Upon exposure to a variety of stresses, HSF1 activates its target genes, subsequently activating the heat shock responses. Although not well understood, the functions of HSF1 are far beyond the classical induction of heat shock responses. Recent reports have shown that HSF1 plays an important role in cancer development. We investigated the role and mechanism of HSF1 in regulating oncogene-mediated dysregulated cellular metabolism and cell growth in cancer cells. We found that oncogene ErbB2-overexpressing cancer cells possessed significantly higher level of glycolysis when compared to ErbB2-low expressing cells, and the downregulation of ErbB2 markedly decreased glycolysis. Overexpression of ErbB2 increased the expression of HSF1 and two critical glycolysis-regulating molecules, lactate dehydrogenase A (LDH-A) and Hexokinase (HK). ErbB2 activated HSF1, indicated by the increased HSF1 trimer formation and DNA binding activity, and promoted the rate of HSF1 protein translation. HSF1 bound to the promoter of LDH-A and transcriptionally activated LDH-A. Meanwhile, the downregulation of HSF1 reduced the expression of LDH-A and subsequently decreased cancer cell glycolysis and growth. These results demonstrate that in cancer cells, ErbB2 promotes glycolysis and cell growth through HSF1-mediated upregulation of LDH-A. Trastuzumab (Herceptin) and Paclitaxel (Taxol) are important drugs in treatment of breast cancers when used alone or in combination with other chemotherapeutics. However, acquired resistance develops in most treated patients, necessitating alternate treatment strategies. Increased aerobic glycolysis is a hallmark of cancer and inhibition of glycolysis may offer a promising strategy to preferentially kill cancer cells. We investigated the antitumor effects of trastuzumab and Taxol in combination with glycolysis inhibitors in breast cancer. We found that trastuzumab inhibits glycolysis via downregulation of HSF1 and LDH-A in ErbB2-positive cancer cells, resulting in tumor growth inhibition. Moreover, increased glycolysis via HSF1 and LDH-A contributes to trastuzumab and Taxol resistance. Strikingly, we found that combining trastuzumab or Taxol with glycolysis inhibition synergistically inhibited both drug-sensitive and -resistant breast cancers in vitro and in vivo, due to more efficient inhibition of glycolysis. These results show how glycolysis inhibition can dramatically enhance the therapeutic efficacy of trastuzumab in ErbB2-positive breast cancers, potentially useful as a strategy to overcome trastuzumab resistance. This work was supported by NIH Grant RO1CA149646, The Vincent F. Kilborn, Jr. Cancer Research Foundation, and Radiumhospitalets Legater Project 334003. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3208. doi:1538-7445.AM2012-3208

Upregulation of lactate dehydrogenase A by ErbB2 through heat shock factor 1 promotes breast cancer cell glycolysis and growth

ErbB2 has been shown to activate signaling molecules that may regulate glucose metabolism. However, there is no evidence reported to directly link ErbB2 to glycolysis, and the mechanism underlying ErbB2-enhanced glycolysis is poorly understood. In this study, we investigated the role and mechanism of ErbB2 in regulating glycolysis. We found that ErbB2-overexpressing cells possessed a significantly higher level of glycolysis when compared to the ErbB2-low-expressing cells, and the downregulation of ErbB2 markedly decreased glycolysis. Overexpression of ErbB2 increased the expression of glycolysis-regulating molecules lactate dehydrogenase A (LDH-A) and heat shock factor 1 (HSF1). ErbB2 activated HSF1, indicated by the increased HSF1 trimer formation, and promoted HSF1 protein synthesis. HSF1 bound to LDH-A promoter and the downregulation of HSF1 reduced the expression of LDH-A and subsequently decreased cancer cell glycolysis and growth. Moreover, the glycolysis inhibitors, 2-deoxyglucose and oxamate, selectively inhibited the growth of ErbB2-overexpressing cells. Taken together, this study shows that in human breast cancer cells, ErbB2 promotes glycolysis at least partially through the HSF1-mediated upregulation of LDH-A. This pathway may have a major role in regulating glucose metabolism in breast cancer cells. These novel findings have important implications for the design of new approaches to target ErbB2-overexpressing breast cancers.