The Experts below are selected from a list of 12936 Experts worldwide ranked by ideXlab platform
Matthew Vander G Heiden - One of the best experts on this subject based on the ideXlab platform.
-
cancer associated mutations in human pyruvate kinase m2 impair enzyme activity
FEBS Letters, 2020Co-Authors: William J Israelsen, Matthew Vander G Heiden, Aaron M Hosios, Vivian M Liu, Andrea J HowellAbstract:Mammalian pyruvate kinase catalyzes the final step of glycolysis, and its M2 isoform (PKM2) is widely expressed in proliferative tissues. Mutations in PKM2 are found in some human cancers; however, the effects of these mutations on enzyme activity and regulation are unknown. Here, we characterized five cancer-associated PKM2 mutations, occurring at various locations on the enzyme, with respect to substrate kinetics and activation by the allosteric activator fructose-1,6-bisphosphate (FBP). The mutants exhibit reduced maximal velocity, reduced substrate affinity, and/or altered activation by FBP. The kinetic parameters of five additional PKM2 mutants that have been used to study enzyme function or regulation also demonstrate the deleterious effects of mutations on PKM2 function. Our findings indicate that PKM2 is sensitive to many amino acid changes and support the hypothesis that decreased PKM2 activity is selected for in rapidly proliferating cells.
-
PKM2 is not required for pancreatic ductal adenocarcinoma
Cancer and Metabolism, 2018Co-Authors: Alissandra L Hillis, Matthew Vander G Heiden, Talya L Dayton, Allison N Lau, Camille X Devoe, Laura V Danai, Dolores Di VizioAbstract:While most cancer cells preferentially express the M2 isoform of the glycolytic enzyme pyruvate kinase (PKM2), PKM2 is dispensable for tumor development in several mouse cancer models. PKM2 is expressed in human pancreatic cancer, and there have been conflicting reports on the association of PKM2 expression and pancreatic cancer patient survival, but whether PKM2 is required for pancreatic cancer progression is unknown. To investigate the role of PKM2 in pancreatic cancer, we used a conditional allele to delete PKM2 in a mouse model of pancreatic ductal adenocarcinoma (PDAC). PDAC tumors were initiated in LSL-KrasG12D/+;Trp53flox/flox;Pdx-1-Cre (KP−/−C) mice harboring a conditional PKM2 allele. Immunohistochemical analysis showed PKM2 expression in wild-type tumors and loss of PKM2 expression in tumors from PKM2 conditional mice. PKM2 deletion had no effect on overall survival or tumor size. Loss of PKM2 resulted in pyruvate kinase M1 (PKM1) expression, but did not affect the number of proliferating cells. These findings are consistent with results in other cancer models. PKM2 is not required for initiation or growth of PDAC tumors arising in the KP−/−C pancreatic cancer model. These findings suggest that, in this mouse PDAC model, PKM2 expression is not required for pancreatic tumor formation or progression.
-
isoform specific deletion of PKM2 constrains tumor initiation in a mouse model of soft tissue sarcoma
Cancer and Metabolism, 2018Co-Authors: Talya L Dayton, Caroline A Lewis, Matthew Vander G Heiden, Vasilena Gocheva, Kathryn M Miller, Arjun Bhutkar, Roderick T Bronson, Tyler JacksAbstract:Alternative splicing of the Pkm gene product generates the PKM1 and PKM2 isoforms of the glycolytic enzyme pyruvate kinase. PKM2 expression is associated with embryogenesis, tissue regeneration, and cancer. PKM2 is also the pyruvate kinase isoform expressed in most wild-type adult tissues, with PKM1 restricted primarily to skeletal muscle, heart, and brain. To interrogate the functional requirement for PKM2 during tumor initiation in an autochthonous mouse model for soft tissue sarcoma (STS), we used a conditional PKM2 allele (PKM2 fl ) to abolish PKM2 expression. PKM2 deletion slowed tumor onset but did not abrogate eventual tumor outgrowth. PKM2-null sarcoma cells expressed PKM1 with tumors containing a high number of infiltrating PKM2 expressing stromal cells. End-stage PKM2-null tumors showed increased proliferation compared to tumors with a wild-type PKM2 allele, and tumor metabolite analysis revealed metabolic changes associated with PKM2 loss. While PKM2 is not required for soft tissue sarcoma growth, PKM2 expression may facilitate initiation of this tumor type. Because these data differ from what has been observed in other cancer models where PKM2 has been deleted, they argue that the consequences of PKM2 loss during tumor initiation are dependent on the tumor type.
-
isoform specific deletion of PKM2 constrains tumor initiation in a mouse model of soft tissue sarcoma
BioMed Central, 2018Co-Authors: Talya L Dayton, Caroline A Lewis, Matthew Vander G Heiden, Vasilena Gocheva, Kathryn M Miller, Arjun Bhutkar, Roderick T Bronson, Tyler JacksAbstract:Background Alternative splicing of the Pkm gene product generates the PKM1 and PKM2 isoforms of the glycolytic enzyme pyruvate kinase. PKM2 expression is associated with embryogenesis, tissue regeneration, and cancer. PKM2 is also the pyruvate kinase isoform expressed in most wild-type adult tissues, with PKM1 restricted primarily to skeletal muscle, heart, and brain. To interrogate the functional requirement for PKM2 during tumor initiation in an autochthonous mouse model for soft tissue sarcoma (STS), we used a conditional PKM2 allele (PKM2 fl ) to abolish PKM2 expression.
-
lack of evidence for PKM2 protein kinase activity
PMC, 2015Co-Authors: Aaron M Hosios, Dan Y Gui, Matthew Vander G Heiden, Brian P FiskeAbstract:The role of pyruvate kinase M2 (PKM2) in cell proliferation is controversial. A unique function of PKM2 proposed to be important for the proliferation of some cancer cells involves the direct activity of this enzyme as a protein kinase; however, a detailed biochemical characterization of this activity is lacking. Using [(32)P]-phosphoenolpyruvate (PEP) we examine the direct substrates of PKM2 using recombinant enzyme and in vitro systems where PKM2 is genetically deleted. Labeling of some protein species from [(32)P]-PEP can be observed; however, most were dependent on the presence of ADP, and none were dependent on the presence of PKM2. In addition, we also failed to observe PKM2-dependent transfer of phosphate from ATP directly to protein. These findings argue against a role for PKM2 as a protein kinase.
William J Israelsen - One of the best experts on this subject based on the ideXlab platform.
-
pyruvate kinase m1 suppresses development and progression of prostate adenocarcinoma
bioRxiv, 2021Co-Authors: Shawn M Davidson, William J Israelsen, Talya L Dayton, Julia E Heyman, James P Obrien, A C Liu, D R Schmidt, R SehgalAbstract:Most cancers, including prostate cancers, express the M2 splice isoform of pyruvate kinase (PKM2). This isoform can promote anabolic metabolism to support cell proliferation; however, PKM2 expression is dispensable for many cancers in vivo. Pyruvate kinase M1 (Pkm1) isoform expression is restricted to relatively few tissues and has been reported to promote growth of select tumors, but the role of PKM1 in cancer has been less studied. Pkm1 is expressed in normal prostate tissue; thus, to test how differential pyruvate kinase isoform expression affects cancer initiation and progression we generated mice harboring a conditional allele of Pkm1 and crossed this allele, as well as a PKM2 conditional allele, to a Pten loss-driven prostate cancer model. We found that Pkm1 loss leads to PKM2 expression and accelerates prostate cancer, while deletion of PKM2 leads to increased Pkm1 expression and suppresses cancer. Consistent with these data, a small molecule pyruvate kinase activator that mimics a PKM1-like state suppresses progression of established prostate tumors. PKM2 expression is retained in most human prostate cancers, arguing that pharmacological PKM2 activation may be beneficial for some prostate cancer patients.
-
cancer associated mutations in human pyruvate kinase m2 impair enzyme activity
FEBS Letters, 2020Co-Authors: William J Israelsen, Matthew Vander G Heiden, Aaron M Hosios, Vivian M Liu, Andrea J HowellAbstract:Mammalian pyruvate kinase catalyzes the final step of glycolysis, and its M2 isoform (PKM2) is widely expressed in proliferative tissues. Mutations in PKM2 are found in some human cancers; however, the effects of these mutations on enzyme activity and regulation are unknown. Here, we characterized five cancer-associated PKM2 mutations, occurring at various locations on the enzyme, with respect to substrate kinetics and activation by the allosteric activator fructose-1,6-bisphosphate (FBP). The mutants exhibit reduced maximal velocity, reduced substrate affinity, and/or altered activation by FBP. The kinetic parameters of five additional PKM2 mutants that have been used to study enzyme function or regulation also demonstrate the deleterious effects of mutations on PKM2 function. Our findings indicate that PKM2 is sensitive to many amino acid changes and support the hypothesis that decreased PKM2 activity is selected for in rapidly proliferating cells.
-
PKM2 is not required for colon cancer initiated by apc loss
Cancer and Metabolism, 2017Co-Authors: Allison N Lau, William J Israelsen, Talya L Dayton, Jatin Roper, Mark J Sinnamon, Larissa Georgeon, Alissandra L HillisAbstract:Cancer cells express the M2 isoform of the glycolytic enzyme pyruvate kinase (PKM2). PKM2 expression is not required for some cancers, and PKM2 loss can promote cancer progression; however, PKM2 has been reported to be essential in other tumor contexts, including a proposed non-metabolic role in β-catenin nuclear translocation. PKM2 is expressed in colon cancers where loss of the Apc tumor suppressor results in β-catenin nuclear translocation and aberrant activation of the canonical Wnt signaling pathway. Whether PKM2 is required in this colon cancer context has not been investigated. Colon tumorigenesis was induced in mice harboring conditional Apc and PKM2 alleles, and tumor progression was monitored by serial colonoscopy. PKM2 deletion had no effect on overall survival, the number of mice that developed tumors, or the number of tumors that developed per animal. Immunohistochemical analysis demonstrated PKM2 expression in wild-type tumors and the expected loss of PKM2 expression in tumors from PKM2 conditional mice. Loss of PKM2 resulted in pyruvate kinase M1 expression but had no effect on nuclear β-catenin staining. These findings are consistent with tumor growth and activated Wnt signaling despite PKM2 loss in this model. We also found a large fraction of human colon cancers had very low or undetectable levels of PKM2 expression. PKM2 is not required for Apc-deficient colon cancer or for nuclear translocation of β-catenin in Apc-null tumor cells. These findings suggest that PKM2 expression is not required for colon tumor formation or progression.
-
germline loss of PKM2 promotes metabolic distress and hepatocellular carcinoma
Genes & Development, 2016Co-Authors: Talya L Dayton, William J Israelsen, Vasilena Gocheva, Kathryn M Miller, Arjun Bhutkar, Roderick T Bronson, Shawn M Davidson, Clary B Clish, Alba Luengo, Tyler JacksAbstract:Alternative splicing of the Pkm gene product generates the PKM1 and PKM2 isoforms of pyruvate kinase (PK), and PKM2 expression is closely linked to embryogenesis, tissue regeneration, and cancer. To interrogate the functional requirement for PKM2 during development and tissue homeostasis, we generated germline PKM2-null mice (PKM2(-/-)). Unexpectedly, despite being the primary isoform expressed in most wild-type adult tissues, we found that PKM2(-/-) mice are viable and fertile. Thus, PKM2 is not required for embryonic or postnatal development. Loss of PKM2 leads to compensatory expression of PKM1 in the tissues that normally express PKM2. Strikingly, PKM2 loss leads to spontaneous development of hepatocellular carcinoma (HCC) with high penetrance that is accompanied by progressive changes in systemic metabolism characterized by altered systemic glucose homeostasis, inflammation, and hepatic steatosis. Therefore, in addition to its role in cancer metabolism, PKM2 plays a role in controlling systemic metabolic homeostasis and inflammation, thereby preventing HCC by a non-cell-autonomous mechanism.
-
PKM2 isoform specific deletion reveals a differential requirement for pyruvate kinase in tumor cells
Cell, 2013Co-Authors: William J Israelsen, Talya L Dayton, Shawn M Davidson, Brian P Fiske, Aaron M Hosios, Gary Bellinger, Jie Li, Yimin Yu, Mika Sasaki, James W HornerAbstract:Summary The pyruvate kinase M2 isoform (PKM2) is expressed in cancer and plays a role in regulating anabolic metabolism. To determine whether PKM2 is required for tumor formation or growth, we generated mice with a conditional allele that abolishes PKM2 expression without disrupting PKM1 expression. PKM2 deletion accelerated mammary tumor formation in a Brca1 -loss-driven model of breast cancer. PKM2 null tumors displayed heterogeneous PKM1 expression, with PKM1 found in nonproliferating tumor cells and no detectable pyruvate kinase expression in proliferating cells. This suggests that PKM2 is not necessary for tumor cell proliferation and implies that the inactive state of PKM2 is associated with the proliferating cell population within tumors, whereas nonproliferating tumor cells require active pyruvate kinase. Consistent with these findings, variable PKM2 expression and heterozygous PKM2 mutations are found in human tumors. These data suggest that regulation of PKM2 activity supports the different metabolic requirements of proliferating and nonproliferating tumor cells. PaperClip
Rameshwar N K Bamezai - One of the best experts on this subject based on the ideXlab platform.
-
pyruvate kinase m2 and cancer an updated assessment
FEBS Letters, 2014Co-Authors: Mohd Askandar Iqbal, Sybille Mazurek, Vibhor Gupta, Prakasam Gopinath, Rameshwar N K BamezaiAbstract:Cancer cells are characterized by high glycolytic rates to support energy regeneration and anabolic metabolism, along with the expression of pyruvate kinase isoenzyme M2 (PKM2). The latter catalyzes the last step of glycolysis and reprograms the glycolytic flux to feed the special metabolic demands of proliferating cells. Besides, PKM2 has moonlight functions, such as gene transcription, favoring cancer. Accumulating evidence suggests a critical role played by the low-activity-dimeric PKM2 in tumor progression, supported by the identification of mutations which result in the down-regulation of its activity and tumorigenesis in a nude mouse model. This review discusses PKM2 regulation and the benefits it confers to cancer cells. Further, conflicting views on PKM2’s role in cancer, its therapeutic relevance and future directions in the field are also discussed.
-
insulin enhances metabolic capacities of cancer cells by dual regulation of glycolytic enzyme pyruvate kinase m2
Molecular Cancer, 2013Co-Authors: Mohd Askandar Iqbal, Vibhor Gupta, Prakasam Gopinath, Farid Ahmad Siddiqui, Shilpi Chattopadhyay, Bhupender Kumar, Siddharth Manvati, Noor Chaman, Rameshwar N K BamezaiAbstract:Insulin is tightly associated with cancer progression; however, mechanistic insights into such observations are poorly understood. Recent studies show that metabolic transformation is critical to cancer cell proliferation. Here, we attempt to understand the role of insulin in promotion of cancer metabolism. To this end, the role of insulin in regulating glycolytic enzyme pyruvate kinase M2 (PKM2) was examined. We observed that insulin up-regulated PKM2 expression, through PI3K/mTOR mediated HIF1α induction, but significantly reduced PKM2 activity independent of this pathway. Drop in PKM2 activity was attributed to subunit dissociation leading to formation of low activity PKM2 oligomers, as assessed by density gradient centrifugation. However, tyrosine 105 phosphorylation of PKM2, known for inhibiting PKM2 activity, remained unaffected on insulin treatment. Interestingly, insulin-induced ROS was found responsible for PKM2 activity reduction. The observed changes in PKM2 status led to augmented cancer metabolism. Insulin-induced PKM2 up-regulation resulted in enhanced aerobic glycolysis as confirmed by PKM2 knockdown studies. Further, PKM2 activity reduction led to characteristic pooling of glycolytic intermediates and increased accumulation of NADPH; suggesting diversion of glucose flux towards macromolecular synthesis, necessary for cancer cell growth. The study identifies new PKM2-mediated effects of insulin on cancer metabolism, thus, advancing the understanding of insulin’s role in cancer.
Zhou Songyang - One of the best experts on this subject based on the ideXlab platform.
-
oncogenic kinase induced PKM2 tyrosine 105 phosphorylation converts nononcogenic PKM2 to a tumor promoter and induces cancer stem like cells
Cancer Research, 2018Co-Authors: Zhifen Zhou, Lin Zhang, Hong Zhao, Ozgur şahin, Jing Chen, Jean J Zhao, Zhou SongyangAbstract:The role of pyruvate kinase M2 isoform (PKM2) in tumor progression has been controversial. Previous studies showed that PKM2 promoted tumor growth in xenograft models; however, depletion of PKM2 in the Brca1-loss-driven mammary tumor mouse model accelerates tumor formation. Because oncogenic kinases are frequently activated in tumors and PKM2 phosphorylation promotes tumor growth, we hypothesized that phosphorylation of PKM2 by activated kinases in tumor cells confers PKM2 oncogenic function, whereas nonphosphorylated PKM2 is nononcogenic. Indeed, PKM2 was phosphorylated at tyrosine 105 (Y105) and formed oncogenic dimers in MDA-MB-231 breast cancer cells, whereas PKM2 was largely unphosphorylated and formed nontumorigenic tetramers in nontransformed MCF10A cells. PKM2 knockdown did not affect MCF10A cell growth but significantly decreased proliferation of MDA-MB-231 breast cancer cells with tyrosine kinase activation. Multiple kinases that are frequently activated in different cancer types were identified to phosphorylate PKM2-Y105 in our tyrosine kinase screening. Introduction of the PKM2-Y105D phosphomimetic mutant into MCF10A cells induced colony formation and the CD44hi/CD24neg cancer stem-like cell population by increasing Yes-associated protein (YAP) nuclear localization. ErbB2, a strong inducer of PKM2-Y105 phosphorylation, boosted nuclear localization of YAP and enhanced the cancer stem-like cell population. Treatment with the ErbB2 kinase inhibitor lapatinib decreased PKM2-Y105 phosphorylation and cancer stem-like cells, impeding PKM2 tumor-promoting function. Taken together, phosphorylation of PKM2-Y105 by activated kinases exerts oncogenic functions in part via activation of YAP downstream signaling to increase cancer stem-like cell properties.Significance: These findings reveal PKM2 promotes tumorigenesis by inducing cancer stem-like cell properties and clarify the paradox of PKM2's dichotomous functions in tumor progression. Cancer Res; 78(9); 2248-61. ©2018 AACR.
-
oncogenic kinase induced PKM2 tyrosine 105 phosphorylation converts nononcogenic PKM2 to a tumor promoter and induces cancer stem like cells
Cancer Research, 2018Co-Authors: Zhifen Zhou, Lin Zhang, Hong Zhao, Ozgur şahin, Jing Chen, Jean J Zhao, Zhou SongyangAbstract:The role of pyruvate kinase M2 isoform (PKM2) in tumor progression has been controversial. Previous studies showed that PKM2 promoted tumor growth in xenograft models; however, depletion of PKM2 in the Brca1-loss-driven mammary tumor mouse model accelerates tumor formation. Since oncogenic kinases are frequently activated in tumors and PKM2 phosphorylation promotes tumor growth, we hypothesized that phosphorylation of PKM2 by activated kinases in tumor cells confers PKM2 oncogenic function, whereas non-phosphorylated PKM2 is non-oncogenic. Indeed, PKM2 was phosphorylated at tyrosine 105 (Y105) and formed oncogenic dimers in MDA-MB-231 breast cancer cells, whereas PKM2 was largely unphosphorylated and formed non-tumorigenic tetramers in non-transformed MCF10A cells. PKM2 knockdown did not affect MCF10A cell growth but significantly decreased proliferation of MDA-MB-231 breast cancer cells with tyrosine kinase activation. Multiple kinases that are frequently activated in different cancer types were identified to phosphorylate PKM2-Y105 in our tyrosine kinase screening. Introduction of the PKM2-Y105D phospho-mimetic mutant into MCF10A cells induced colony formation and the CD44hi/CD24neg cancer stem-like cell population by increasing YAP protein nuclear localization. ErbB2, a strong inducer of PKM2-Y105 phosphorylation, boosted nuclear localization of YAP and enhanced the cancer stem-like cell population. Treatment with the ErbB2 kinase inhibitor lapatinib decreased PKM2-Y105 phosphorylation and cancer stem-like cells, impeding PKM2 tumor-promoting function. Taken together, phosphorylation of PKM2-Y105 by activated kinases exerts oncogenic functions in part via activation of YAP downstream signaling to increase cancer stem-like cell properties.
Costas A. Lyssiotis - One of the best experts on this subject based on the ideXlab platform.
-
Small molecule activation of metabolic enzyme pyruvate kinase muscle isozyme 2, PKM2, circumvents photoreceptor apoptosis.
Scientific reports, 2020Co-Authors: Thomas J. Wubben, Mercy Pawar, Eric Weh, Andrew M. Smith, Peter Sajjakulnukit, Li Zhang, Lipeng Dai, Heather Hager, Manjunath P. Pai, Costas A. LyssiotisAbstract:Photoreceptor cell death is the ultimate cause of vision loss in many retinal disorders, and there is an unmet need for neuroprotective modalities to improve photoreceptor survival. Similar to cancer cells, photoreceptors maintain pyruvate kinase muscle isoform 2 (PKM2) expression, which is a critical regulator in aerobic glycolysis. Unlike PKM1, which has constitutively high catalytic activity, PKM2 is under complex regulation. Recently, we demonstrated that genetically reprogramming photoreceptor metabolism via PKM2-to-PKM1 substitution is a promising neuroprotective strategy. Here, we explored the neuroprotective effects of pharmacologically activating PKM2 via ML-265, a small molecule activator of PKM2, during acute outer retinal stress. We found that ML-265 increased PKM2 activity in 661 W cells and in vivo in rat eyes without affecting the expression of genes involved in glucose metabolism. ML-265 treatment did, however, alter metabolic intermediates of glucose metabolism and those necessary for biosynthesis in cultured cells. Long-term exposure to ML-265 did not result in decreased photoreceptor function or survival under baseline conditions. Notably, though, ML-265-treatment did reduce entrance into the apoptotic cascade in in vitro and in vivo models of outer retinal stress. These data suggest that reprogramming metabolism via activation of PKM2 is a novel, and promising, therapeutic strategy for photoreceptor neuroprotection.
-
Small molecule activation of metabolic enzyme pyruvate kinase muscle isozyme 2, PKM2, provides photoreceptor neuroprotection
2019Co-Authors: Thomas J. Wubben, Mercy Pawar, Eric Weh, Andrew M. Smith, Peter Sajjakulnukit, Li Zhang, Lipeng Dai, Heather Hager, Manjunath P. Pai, Costas A. LyssiotisAbstract:Abstract Photoreceptor cell death is the ultimate cause of vision loss in many retinal disorders, and there is an unmet need for neuroprotective modalities to improve photoreceptor survival. Similar to cancer cells, photoreceptors maintain pyruvate kinase muscle isoform 2 (PKM2) expression, which is a critical regulator in aerobic glycolysis. Unlike PKM1, which has constitutively high catalytic activity, PKM2 is under complex regulation. Recently, we demonstrated that genetically reprogramming photoreceptor metabolism via PKM2-to-PKM1 substitution is a promising neuroprotective strategy. Here, we explored the neuroprotective effects of pharmacologically activating PKM2 via ML-265, a small molecule activator of PKM2, during acute outer retinal stress. We found that ML-265 increased PKM2 activity in 661W cells and in vivo in rat eyes without affecting the expression of genes involved in glucose metabolism. ML-265 treatment did, however, alter metabolic intermediates of glucose metabolism and those necessary for biosynthesis in cultured cells. Long-term exposure to ML-265 did not result in decreased photoreceptor function or survival under baseline conditions. Notably, though, ML-265-treatment did reduce entrance into the apoptotic cascade in in vitro and in vivo models of outer retinal stress. These data suggest that reprogramming metabolism via activation of PKM2 is a novel, and promising, therapeutic strategy for photoreceptor neuroprotection.