Pyruvate Kinase M2 Levels Research Articles

PKM2 Is Required to Activate Myeloid Dendritic Cells from Patients with Severe Aplastic Anemia.

Severe aplastic anemia (SAA) is an autoimmune disease in which bone marrow failure is mediated by activated myeloid dendritic cells (mDCs) and T lymphocytes. Recent research has identified a strong immunomodulatory effect of pyruvate kinase M2 (PKM2) on dendritic cells in immune-mediated diseases. In this study, we aimed to explore the role of PKM2 in the activation of mDCs in SAA. We observed conspicuously higher levels of PKM2 in mDCs from SAA patients compared to normal controls at both the gene and protein levels. Concurrently, we unexpectedly discovered that after the mDC-specific downregulation of PKM2, mDCs from patients with SAA exhibited weakened phagocytic activity and significantly decreased and shortened dendrites relative to their counterparts from normal controls. The expression levels of the costimulatory molecules CD86 and CD80 were also reduced on mDCs. Our results also suggested that PKM2 knockdown in mDCs reduced the abilities of these cells to promote the activation of CD8+ T cells (CTLs), leading to the decreased secretion of cytotoxic factors by the latter cell type. These findings demonstrate that mDC activation requires an elevated intrinsic PKM2 level and that PKM2 improves the immune status of patients with SAA by enhancing the functions of mDCs and, consequently, CTLs.

PKM2 Inhibitor Shikonin Overcomes the Cisplatin Resistance in Bladder Cancer by Inducing Necroptosis.

Cisplatin-based chemotherapy often results in the development of chemo-resistance when used to treat bladder cancer (BC), which is difficult to overcome. Recent data indicate that pyruvate kinase M2 (PKM2), a glycolytic enzyme for Warburg effect, is strongly upregulated in BC, and contributes to the cisplatin resistance in BC. However, the underlying mechanisms remain unclear. In this study, we also found that the expression level of PKM2 is also higher in cisplatin resistant BC cells and tumors. Down-regulation of PKM2 by siRNA or inhibition of PKM2 by shikonin re-sensitized the cisplatin resistant T24 cells. Shikonin and cisplatin together exhibit significantly greater killing effects than when used alone. Interestingly, we found shikonin kills the T24 cisplatin resistant cells by inducing necroptosis, as the cell death could not inhibited by apoptosis inhibitor, z-VAD, but compromised by RIP3 inhibitor, GSK872, or RIP3 siRNA. In contrast, shikonin induced apoptosis in T24 parental cells. We further investigate the underlying mechanism, and found that the dysregulation of Bcl-2 family proteins, including Bcl-2, PUMA, Bax, play an important role in deciding that shikonin kills the BC cells by necroptosis or apoptosis. Collectively, our results suggested that inducing necroptosis is an alternative way to overcome the apoptosis resistant in BC therapy, and orchestrating the regulation of Bcl-2, PUMA, and Bax in BC cisplatin resistant cells may improve the therapy effect of cisplatin in BC tumor.

Pyruvate kinase M2 inhibits the progression of bladder cancer by targeting MAKP pathway.

Pyruvate kinase M2 (PKM2) was found overexpressed in tumor cells and played a significant role in tumor formation and growth. We sought to explore the correlation of PKM2 expression with cell proliferation, invasion, and apoptosis in bladder cancer cell line. Real-time polymerase chain reaction and Western blot were performed to determine the expression level of PKM2 at mRNA and protein level. MTT and flow cytometry were respectively used to explore the proliferation, invasion, and apoptosis in bladder cancer cell line in vitro. The results suggested that suppression of PKM2 significantly decreased the proliferation rate, invasive cell number, and migration ability of bladder cancer cells compared with blank group. Moreover, proteins such as MMP2 and MMP9 as well as P38 expression were also affected by the PKM2 expression changes. These results proved that PKM2 could be involved in the progression of bladder cancer by mitogen-activated protein kinases signaling pathway. The data presented in this study revealed that PKM2 up-regulation may promote the development and metastasis of bladder cancer through promoting cell proliferation, migration and invasion via MAPK signal pathway.

Elevation of serum pyruvate kinase M2 (PKM2) in IBD and its relationship to IBD indices

ObjectivesEndoscopy remains the gold standard to diagnose and evaluate inflammatory bowel disease (IBD) activity. Current biomarkers or their combinations cannot adequately predict IBD risk, diagnosis, progression or relapse, and response to therapy. Pyruvate kinase M2 (PKM2) is emerging as a significant mediator of the inflammatory process. We aimed to assess levels of serum PKM2 in healthy and newly diagnosed IBD patients and its relationship with IBD indices and microbiota changes. Design and methodsIBD serum samples from newly diagnosed patients were collected and analyzed using a PKM2-ELISA and correlated with disease activity scores, IBD disease type, and intestinal microbiota. Furthermore, we tested the genetic and protein expression of PKM2 in an in vitro intestinal cell model of inflammation. ResultsSerum PKM2 levels were 6-fold higher in IBD patients compared to healthy controls, with no sensitivity to disease phenotype (Crohn's Disease or Ulcerative Colitis) or localization of inflammation. Serum PKM2 had considerably less interindividual variability than established IBD fecal biomarkers. A positive Pearson correlation (r=0.6121) existed between serum PKM2 and Bacteroidetes fecal levels in Crohn's disease (CD), while a negative (r=−0.6128) correlation was observed with Actinobacteria fecal levels. Furthermore, LPS (500ng/mL) significantly increased PKM2 expression in vitro, which was significantly suppressed by an anti-inflammatory flaxseed bioactive agent. ConclusionOur data suggests PKM2 as a putative biomarker for IBD and the dysbiosis of microflora in CD. Investigations involving larger number of clinical patients are necessary to validate its use as a serum biomarker of IBD.

Pyruvate kinase M2 is a poor prognostic marker of and a therapeutic target in ovarian cancer

Pyruvate kinase M2 (PKM2) regulates glycolysis and oxidative phosphorylation; however, the role of PKM2 in ovarian cancer remains largely unknown. We investigated whether ovarian cancer metabolism could provide insight into the development of therapeutic strategies. We performed immunohistochemical staining for PKM2 on a tissue microarray for multivariate analysis. It revealed that patients exhibiting higher PKM2 expression were significantly associated with malignancy groups (p < 0.001) and pathogenesis models (p < 0.001), had poor progression-free survival rates (p = 0.01) as compared with patients exhibiting lower PKM2 levels, and yielded a hazard ratio of death of 2.02 (95% confidence interval: 0.70–5.85). In cell lines, PKM2 inhibitor significantly inhibited the glycolytic rate according to cellular glucose consumption (p < 0.001). We also utilized Seahorse assays to assess metabolism-related cell-specific factors and the impact of PKM2 inhibitors. Energy shifts as per Seahorse analysis showed attenuation of the extracellular acidification rate (p < 0.05) and no significant difference in oxygen-consumption rate in SKOV3 cells. Treatment with PKM2 inhibitor suppressed ovarian cancer growth and cell migration in vitro and inhibited tumor growth without significant toxicity in a xenograft study. PKM2 inhibition disturbed Warburg effects and inhibited ovarian cancer cell growth. Targeting PKM2 may constitute a promising therapy for patients with ovarian cancer, and clinical trials involving shikonin are warranted.

Pyruvate kinase M2 interacts with mammalian sterile 20-like kinase 1 and inhibits tamoxifen-induced apoptosis in human breast cancer cells.

Tamoxifen has been reported to be associated with antagonism of estrogen-mediated cell growth signaling and activation of estrogen receptor-independent apoptosis events. It has been demonstrated that mammalian sterile 20-like kinase 1 is a direct target of Caspases to amplify the apoptotic signaling pathway. Here, we presented that breast cancer MCF-7 and SKBR3 cells under treatment with 4-hydroxytamoxifen displayed decreased level of pyruvate kinase M2. Western blot results also showed that 4-hydroxytamoxifen induced the activity of pro-apoptotic protein Caspase-3 in MCF-7 and SKBR3 cells, as evidenced by the cleavage of mammalian sterile 20-like kinase 1 substrate in a dose-dependent manner. Co-immunoprecipitation and immunofluorescence experiments were performed to clarify the relationship between pyruvate kinase M2 and mammalian sterile 20-like kinase 1. The results indicated that mammalian sterile 20-like kinase 1 was associated with pyruvate kinase M2 in cultured mammalian cells, and the interaction between mammalian sterile 20-like kinase 1 and pyruvate kinase M2 was decreased in response to 4-hydroxytamoxifen treatment. In addition, knockdown of pyruvate kinase M2 upregulated the level of cleaved Caspase-3 and subsequently facilitated the nuclear translocation of mammalian sterile 20-like kinase 1. Our data further supplemented the extensive functions of pyruvate kinase M2 in mediating breast cancer cell viability by substantially abating the mammalian sterile 20-like kinase 1-mediated apoptosis. In summary, our results identified that mammalian sterile 20-like kinase 1 is a novel downstream target of pyruvate kinase M2, and knockdown of pyruvate kinase M2 contributes apoptosis via promoting nuclear translocation of mammalian sterile 20-like kinase 1 by enhancing Caspase-3-dependent cleavage.

Cytosolic PKM2 stabilizes mutant EGFR protein expression through regulating HSP90-EGFR association.

This corrects the article DOI: 10.1038/onc.2015.397.

Influenza Virus Infection Induces Host Pyruvate Kinase M Which Interacts with Viral RNA-Dependent RNA Polymerase.

Influenza virus RNA-dependent RNA polymerase (RdRp) is a heterotrimer of three viral proteins, PB1, PB2, and PA and is involved in both transcription and replication of the negative strand of the viral RNA (vRNA) genome. RdRp is multifunctional, possessing RNA polymerase, cap binding, and endonuclease activities. The enzyme synthesizes three different RNAs, complementary RNA (cRNA) and messenger RNA (mRNA) from vRNA, and vRNA from cRNA. To synthesize these three RNAs, RdRp requires conversion of its function by host factor. Here, we performed yeast two-hybrid screening to identify the relevant host factor, revealing that pyruvate kinase M2 (PKM2) interacted with the PA subunit of influenza virus RdRp. PKM2 is one of two enzymes (PKM1 and PKM2) produced by alternative splicing of the pyruvate kinase M (PKM) pre-mRNA. We determined the interacting regions in both PKM2 and PA, the expression level of PKM by western blotting at different time points after viral infection, and the effects of transfection of siRNA targeting PKM on influenza virus replication. The results demonstrated that the C-terminal region of PKM2 interacted with the C-terminus of the PA subunit, that the expression level of PKM2 increased with influenza virus infection time, and that this enzyme is essential for influenza virus multiplication. Moreover, isoelectric focusing of uninfected and influenza virus infected cell extracts, followed by gradient gel electrophoresis to separate the PKM1 and PKM2 isoforms and western blotting indicated that PKM2 became more acidic after influenza infection. The decreased pH of PKM2 may have been due to phosphorylation, and phosphorylated PKM2 is active as a pyruvate kinase and protein kinase; therefore, it is possible that PKM2 may transfer a phosphate group to PA and consequently transform the function of RdRp from transcriptase to replicase.

Desuccinylation of pyruvate kinase M2 by SIRT5 contributes to antioxidant response and tumor growth

Tumor cells trends to express high level of pyruvate kinase M2 (PKM2). The inhibition of PKM2 activity is needed for antioxidant response by diverting glucose flux into the pentose phosphate pathway and thus generating sufficient reducing potential. Here we report that PKM2 is succinylated at lysine 498 (K498) and succinylation increases its activity. SIRT5 binds to, desuccinylates and inhibits PKM2 activity. Increased level of reactive oxygen species (ROS) decreases both the succinylation and activity of PKM2 by increasing its binding to SIRT5. Substitution of endogenous PKM2 with a succinylation mimetic mutant K498E decreases cellular NADPH production and inhibits cell proliferation and tumor growth. Moreover, inhibition of SIRT5 suppresses tumor cell proliferation through desuccinylation of PKM2 K498. These results reveal a new mechanism of PKM2 modification, a new function of SIRT5 in response to oxidative stress which stimulates cell proliferation and tumor growth, and also a potential target for clinical cancer research.

The Role of PKM2 in the Activation of Myeloid Dendritic Cells from Patients with Severe Aplastic Anemia

Severe aplastic anemia (SAA) is a hematologic disease characterized by severe bone marrow failure. The abnormal activation of myeloid dendritic cells (mDCs) in SAA might accelerate the polarization of Th0 cells to Th1 cells ,thus causing the over-function of T lymphocytes and apoptosis of hematopoietic cells. Hence, mDCs played an important role in the primary stage of the immune response.Here, we analyze the protein components of mDC from SAA as well as normal control to explore the possible reason that activate mDC. The protein components of mDCs was detected by proteomics technology. Furtherly we applied both realtime PCR and western blot from a perspective of mRNA and protein to validate our discovery. Results revealed that expression of pyruvate kinase M2(PKM2) were enhanced in mDCs from SAA patients at an early stage of the onset. Concurrently, the level of PKM2 in mDCs of SAA patients was conspicuously higher than that in normal control not only at a protein level but also at the gene level.To clarify the role of PKM2 in the activation of mDCs, we investigate the effect of targeted PKM2 siRNA -knockout in mDCs at the cellular level. We measured the levels of costimulatory molecules CD80 and CD86 on mDCs by flow cytometry and identified significantly higher expression of CD86 in the control group relative to the transfected group.To quantify antigen uptake and processing capacities of mDCs, cells were treated with carboxylate-modified yellow-green (YG) microspheres and then analyzed by flow cytometry. The percentage of phagocytosis (PP) was determined by the following formula: PP = M1 + M2 + M3 + M4, where M1, M2, M3, and M4 correspond to the number of cells with one, two, three and four microspheres. Phagocytosis index(PI)=(intracellular cpms/ intracellular + extracellular cpms)x100%.After PKM2 siRNA transfection, we observed lower phagocytic ability of mDCs. Additionally, the level of PP of mDCs from control group was higher than that of PKM2 siRNA -knockout group. Through scanning electron microscopy (SEM), mDCs before siRNA transfection from SAA patients presented longer and more branched protrusions than those seen in PKM2 siRNA transfected mDCs.Next, the effects of PKM2 on cytotoxic T cells(CTL) activation by mDCs from SAA patients were also determined. mDCs before and after PKM2 siRNA transfection were co cultured with CTL cells for 72 hours. After cell co culture, the mRNA expressions of perforin were identified significantly higher in the control group relative to the transfected group. Culture supernatant were collected for quantification of IFN-γ and IL-4 by commercial ELISA kits. The levels of IFN-γ and IL-4 in contral group were much higher than that of transfected group .Additionally, flow cytometry experiments assessing annexin V/propidium iodide staining showed that high PKM2 expression in mDCs was significantly associated with reduced apoptosis rate of CTLs. Therefore, the enhanced function of mDCs from SAA could activate the downstream CTL function and then enhance the killing effect to target cells.Our findings demonstrated that elevated levels of PKM2 in mDCs play an important role in the activation of mDCs and thereby affecting the immune status of SAA by enhancing the function of mDCs and downstream CTLs. DisclosuresNo relevant conflicts of interest to declare.

Pyruvate kinase M2 (PKM2) expression correlates with prognosis in solid cancers: a meta-analysis.

Pyruvate kinase M2 (PKM2) is the key enzyme in the Warburg effect and plays a central role in cancer cell metabolic reprogramming. Recently, quite a few studies have investigated the correlation between PKM2 expression and prognosis in multiple cancer patients, but results were inconsistent. We therefore performed a meta-analysis to explore the prognostic value of PKM2 expression in patients with solid cancer. Here twenty-seven individual studies from 25 publications with a total of 4796 cases were included to explore the association between PKM2 and overall survival (OS) or disease-free survival (DFS)/ progression-free survival (PFS)/ recurrent-free survival (RFS) in subjects with solid cancer. Pooled analysis showed that high levels of PKM2 was significantly associated with a poorer overall survival (HR = 1.73; 95%CI = 1.48-2.03) and DFS/ PFS/ RFS (HR = 1.90; 95%CI = 1.39-2.59) irrespective of cancer types. Different analysis models (univariate or multivariate models), sample-sizes (≤100 or >100), and methods for data collection (direct extraction or indirect extraction) had no impact on the negative prognostic effect of PKM2 over-expression. Nevertheless, stratified by cancer type, high-expression of PKM2 was associated with an unfavorable OS in breast cancer, esophageal squamous carcinoma, hepatocellular carcinoma and gallbladder cancer; whereas was not correlated with a worse OS in pancreatic cancer and gastric cancer. In conclusion, over-expression of PKM2 is associated with poor prognosis in most solid cancers and it might be a potentially useful biomarker for predicting cancer prognosis in future clinical applications.

Abstract 3482: Inhibition of glucose metabolism in neuroendocrine tumors by lanreotide, sunitinib, and rapamycin

Abstract Background: Neuroendocrine tumors (NETs) represent a heterogeneous family of neoplasms, which may develop from different endocrine glands or endocrine cells dispersed throughout the digestive and respiratory tracts. Lanreotide is a somatostatin analog approved for the treatment of NETs. While Lanreotide extends survival of patients and slows tumor growth, controversy exists regarding its mechanism of action. We hypothesized that lanreotide can interfere with the metabolic activity of NETs, and compared its effect to that of rapamycin and sunitinib. Methods: The pancreatic carcinoid BON-1 cells and pulmonary carcinoid NCI-H727 cells were used. Viability was tested using colony formation assay. mRNA levels of the glycolytic enzymes hexokinase 2 (HK2), lactate dehydrogenase (LDH) and pyruvate kinase M2 (PKM2) was tested using real-time PCR. Phosphorylation levels of AMP-activated kinase (AMPK) and acetyl CoA carboxylase (ACC) were tested using Western blot. The activity of HK2 was tested using HK enzymatic assay. Lactate secretion was tested in the routine biochemistry laboratory of our institution. Results: Lanreotide, rapamycin and sunitinib significantly decreased colony formation. They also reduced relative expression levels of HK2, LDH and PKM2 24 and 48h after treatment and decreased HK2 activity after 24h. An increase in the phosphorylation levels of AMPK and ACC was observed shortly after treating the cells with lanreotide and rapamycin. All three agents also decreased lactate concentration in the media. Conclusions: These data indicate tumor metabolism as an attractive target for therapies against NET, and a novel mechanism of action of somatostatin analogs, namely, alteration of tumor metabolism. Citation Format: Tami Rubinek, Ayelet Shabtay-Orbach, Arkadi Hesin, Tammi Rubinstein, Ido Wolf. Inhibition of glucose metabolism in neuroendocrine tumors by lanreotide, sunitinib, and rapamycin. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3482.

SIRT6 deacetylates PKM2 to suppress its nuclear localization and oncogenic functions

SIRT6 (sirtuin 6) is a member of sirtuin family of deacetylases involved in diverse processes including genome stability, metabolic homeostasis, and tumorigenesis. However, the role of SIRT6 deacetylase activity in its tumor-suppressor functions is not well understood. Here we report that SIRT6 binds to and deacetylates nuclear PKM2 (pyruvate kinase M2) at the lysine 433 residue. PKM2 is a glycolytic enzyme with nonmetabolic nuclear oncogenic functions. SIRT6-mediated deacetylation results in PKM2 nuclear export. We further have identified exportin 4 as the specific transporter mediating PKM2 nuclear export. As a result of SIRT6-mediated deacetylation, PKM2 nuclear protein kinase and transcriptional coactivator functions are abolished. Thus, SIRT6 suppresses PKM2 oncogenic functions, resulting in reduced cell proliferation, migration potential, and invasiveness. Furthermore, studies in mouse tumor models demonstrate that PKM2 deacetylation is integral to SIRT6-mediated tumor suppression and inhibition of metastasis. Additionally, reduced SIRT6 levels correlate with elevated nuclear acetylated PKM2 levels in increasing grades of hepatocellular carcinoma. These findings provide key insights into the pivotal role of deacetylase activity in SIRT6 tumor-suppressor functions.

Abnormal Levels of PKM2 in Mdcs from Patients with Severe Aplastic

Severe aplastic anemia (SAA) is a hematologic disease characterized by pancytopenia with severe bone marrow failure. Our previous studies have demonstrated that activated myeloid dendritic cells (mDCs) increased in the bone marrow of SAA patients, which might promote Th0 cells to polarize to Th1 cells and cause the subsequent over-function of T lymphocytes and hematopoiesis failure in SAA. The other notable finding in our study is that abnormal expression of pyruvate kinase M2 (PKM2) in mDCs from SAA patients may be one of the reason for mDC hyperfunction. Human pyruvate kinase M2, which catalyzes the last but rate-limiting step of glycolysis, is exclusively expressed in actively proliferated cells ,especially in embryonic and adult dividing/tumor cells. It remains unclear how PKM2 may change in patients with SAA. This study aims at exploring the role of PKM2 in SAA. In this study, the quantitative changes of mDCs in peripheral blood of 15 SAA patients before immunosuppressive therapy (IST) °¢ 13 SAA patients after IST and 26 normal controls were determined by flow cytometry. Results showed that the levels of PKM2 in mDCs were significantly increased in SAA patients(59.1±15.8)%. After IST, the levels of PKM2 in mDCs decreased(42.6±22.1)% (P<0.05).In normal controls group , the level of PKM2 in mDCs was (32.7±20.2)%. These changes reveal that dysregulation of PKM2 expression and activation in mDCs from SAA patients may contribute to hyperfunction of mDCs, thus leading to the imbalance of downstream Th1/Th2 subsets which followed by hematopoiesis failure in SAA. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Cytosolic PKM2 stabilizes mutant EGFR protein expression through regulating HSP90-EGFR association.

Secondary mutation of epidermal growth factor receptor (EGFR) resulting in drug resistance is one of the most critical issues in lung cancer therapy. Several drugs are being developed to overcome EGFR tyrosine kinase inhibitor (TKI) resistance. Here, we report that pyruvate kinase M2 (PKM2) stabilized mutant EGFR protein by direct interaction and sustained cell survival signaling in lung cancer cells. PKM2 silencing resulted in markedly reduced mutant EGFR expression in TKI-sensitive or -resistant human lung cancer cells, and in inhibition of tumor growth in their xenografts, concomitant with downregulation of EGFR-related signaling. Mechanistically, PKM2 directly interacted with mutant EGFR and heat-shock protein 90 (HSP90), and thus stabilized EGFR by maintaining its binding with HSP90 and co-chaperones. Stabilization of EGFR relied on dimeric PKM2, and the protein half-life of mutant EGFR decreased when PKM2 was forced into its tetramer form. Clinical levels of PKM2 positively correlated with mutant EGFR expression and with patient outcome. These results reveal a previously undescribed non-glycolysis function of PKM2 in the cytoplasm, which contribute to EGFR-dependent tumorigenesis and provide a novel strategy to overcome drug resistance to EGFR TKIs.

Modulation of Ovarian Cancer Cell Metabolism via Pyruvate Kinase M2 (PKM2) and Glucose Deprivation

Ovarian cancer is one of the most aggressive types of cancer in women. While the molecular mechanisms of ovarian cancer have been extensively studied, treatments for ovarian cancer are still limited. Understanding the metabolism of ovarian cancer cells has been of great interest to many scientists. Cancer cells express a higher consumption rate of glucose which results in accumulation of lactate even in an oxygenized environment. This alteration in metabolism is known as the Warburg effect and is necessary for the growth and survival of cancer cells. Pyruvate kinase M2 or PKM2 has been shown to be a regulator enzyme responsible for the conversion of PEP to pyruvate. Recent studies have demonstrated that PKM2 is over‐expressed in tumor cells. However, its functions are yet to be elucidated. In this project, we investigated the effects of glucose deprivation on ovarian cancer cells (CaOV3 cell line). The results showed that reduction of glucose supply in culture medium affects cells morphologically and metabolically. MTT assay data showed that glucose alters cellular proliferation in a dose dependent manner. Lower glucose supply results in alkalinization of culture medium. Seahorse data indicated that glucose deprivation reduces oxygen consumption rate of ovarian cancer cells. Western blot analysis and confocal microscopy demonstrated that PKM2 expression is altered in the cytoplasm in response to glucose deprivation. PKM2 levels decrease 30 mins post 1 mM glucose treatment, reaches to the lowest at 1 hr, recovering within 2 hrs. Collectively, our data suggest that PKM2 may be a molecular target for ovarian cancer treatment and glucose deprivation may be a potential approach for modulation of PKM2.

Phosphorylation of pyruvate kinase M2 and lactate dehydrogenase A by fibroblast growth factor receptor 1 in benign and malignant thyroid tissue.

BackgroundLactate dehydrogenase A (LDHA) and Pyruvate Kinase M2 (PKM2) are important enzymes of glycolysis. Both of them can be phosphorylated and therefore regulated by Fibroblast growth factor receptor 1 (FGFR1). While phosphorylation of LDHA at tyrosine10 leads to tetramerization and activation, phosphorylation of PKM2 at tyrosine105 promotes dimerization and inactivation. Dimeric PKM2 is found in the nucleus and regulates gene transcription. Up-regulation and phosphorylation of LDHA and PKM2 contribute to faster proliferation under hypoxic conditions and promote the Warburg effect.MethodsUsing western blot and SYBR Green Real time PCR we investigated 77 thyroid tissues including 19 goiter tissues, 11 follicular adenomas, 16 follicular carcinomas, 15 papillary thyroid carcinomas, and 16 undifferentiated thyroid carcinomas for total expression of PKM2, LDHA and FGFR1. Additionally, phosphorylation status of PKM2 and LDHA was analysed. Inhibition of FGFR was performed on FTC133 cells with SU-5402 and Dovitinib.ResultsAll examined thyroid cancer subtypes overexpressed PKM2 as compared to goiter. LDHA was overexpressed in follicular and papillary thyroid cancer as compared to goiter. Elevated phosphorylation of LDHA and PKM2 was detectable in all analysed cancer subtypes. The highest relative phosphorylation levels of PKM2 and LDHA compared to overall expression were found in undifferentiated thyroid cancer. Inhibition of FGFR led to significantly decreased phosphorylation levels of PKM2 and LDHA.ConclusionsOur data shows that overexpression and increased phosphorylation of PKM2 and LHDA is a common finding in thyroid malignancies. Phospho-PKM2 and Phospho-LDHA could be valuable tumour markers for thyroglobulin negative thyroid cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1135-y) contains supplementary material, which is available to authorized users.

Pyruvate kinase M2 prevents apoptosis via modulating Bim stability and associates with poor outcome in hepatocellular carcinoma.

Pyruvate kinase M2 (PKM2) contributes to the Warburg effect, a hallmark of cancer. We showed that PKM2 levels were correlated with overall survival (hazard ration = 1.675, 95% confidence interval: 1.389-2.019, P < 0.001) and disease-free survival (hazard ration = 1.573, 95% confidence interval: 1.214-2.038, P < 0.001) in a cohort of 490 patients with HCC. The correlations were further validated in an independent cohort of 148 HCC patients. Multivariate analyses revealed that PKM2 was an independent indicator of poor outcome in HCC. The knockdown of PKM2 in HCC cells inhibited cell proliferation and induced apoptosis in vitro and in vivo. Bim siRNA markedly abolished the PKM2-depletion-induced apoptosis. PKM2 depletion decreased the degradation of Bim. In clinical samples, PKM2 expression was reversely correlated with Bim expression. Combination of PKM2 and Bim levels had the best prognostic significance. We suggest that PKM2 serves as a promising biomarker for poor prognosis of patients with HCC and its knockdown induces HCC apoptosis by stabilizing Bim.

Overexpression of metabolic markers PKM2 and LDH5 correlates with aggressive clinicopathological features and adverse patient prognosis in tongue cancer.

Pyruvate kinase M2 (PKM2) and lactate dehydrogenase 5 (LDH5) are two metabolic and oncogenic markers of cancer. In this study, we sought to investigate their expression patterns and prognostic value in tongue squamous cell carcinoma (TSCC). The expression and subcellular localization of PKM2 and LDH5 in TSCC cell lines were determined by Western blot and immunofluorescence. PKM2 and LDH5 abundance was examined by immunohistochemistry in 63 TSCC tumour specimens; their association with multiple clinicopathological parameters and overall patient survival was assessed. The protein levels of PKM2 and LDH5 were both significantly higher in TSCC cells than in an immortalized oral epithelial cell line. Overexpression of PKM2 associated significantly with cervical node metastasis (P=0.0373), while elevated LDH5 levels correlated significantly with tumour size (P=0.0094), pathological grade (P=0.0052), cervical node metastasis (P=0.0023) and clinical stage (P=0.0024). Patients with tumours showing an increase in either PKM2 or LDH5 expression displayed significantly reduced overall survival, while patients with tumours overexpressing both proteins showed the worst prognosis with lowest overall survival. Furthermore, PKM2 and LDH5 were identified as independent prognostic predictors for overall patient survival in TSCC. Our data indicate that overexpression of PKM2 and LDH5 associates with key clinicopathological features and unfavourable prognosis in TSCC.

Changes in PKM2 Associate with Prostate Cancer Progression

Pyruvate kinase M2 (PKM2) is essential for aerobic glycolysis, the dominant metabolic pathway utilized by cancer cells. To determine the association of PKM2 with prostate cancer (PC), we examined 29 primary PC and three lymph node metastatic tumors; elevation of PKM2 was observed in Gleason 8–10 tumors compared to Gleason 6–7 carcinomas. High PKM2 was detected by immunohistochemistry in more aggressive xenograft tumors derived from PC stem-like cells (PCSCs) compared to those produced from non-PCSCs. While PCSCs and non-PCSCs expressed comparable levels of PKM2, distinct posttranslational modifications were observed. Collectively, upregulation and specific modification to PKM2 associate with PC progression.