The M2 splice isoform of pyruvate kinase (PKM2), an enzyme that catalyzes the later step of glycolysis, is a key regulator of aerobic glycolysis (known as the Warburg effect) in cancer cells. Expression and low enzymatic activity of PKM2 confer on cancer cells the glycolytic phenotype, which promotes rapid energy production and flow of glycolytic intermediates into collateral pathways to synthesize nucleic acids, amino acids, and lipids without the accumulation of reactive oxygen species. PKM2 enzymatic activity has also been shown to be negatively regulated by the interaction with CD44 adhesion molecule, which is a cell surface marker for cancer stem cells. In addition to the glycolytic functions, nonglycolytic functions of PKM2 in cancer cells are of particular interest. PKM2 is induced translocation into the nucleus, where it activates transcription of various genes by interacting with and phosphorylating specific nuclear proteins, endowing cancer cells with a survival and growth advantage. Therefore, inhibitors and activators of PKM2 are well underway to evaluate their anticancer effects and suitability for use as novel therapeutic strategies. Clin Cancer Res; 18(20); 5554–61. ©2012 AACR.

Obtaining sufficient energy is a critical issue for cells to survive. Regardless of local availability of molecular oxygen, mainly cancer cells primarily use glycolysis to produce ATP. This unique feature is called aerobic glycolysis or the Warburg effect (1, 2). Recent studies show that pyruvate kinase M2 (PKM2) is a key glycolytic enzyme that regulates the Warburg effect and is necessary for tumor growth (3). Incorporated glucose is converted into pyruvate through several steps in cytoplasm (Fig. 1). Pyruvate can be converted to lactate or to acetyl-CoA, and such direction is determined by the enzymatic activity of PKM2 (3–6). Low PKM2 activity promotes conversion to lactate and leads to Warburg effect, whereas high activity of both PKM2 and PKM1 promotes conversion to acetyl-CoA (Fig. 1; refs. 3–6). Recently, not only the glycolytic but also the nonglycolytic functions of PKM2 have attracted a great deal of attention. In this review, we describe the functions of PKM2 in cancer cells and discuss potential therapeutic applications.

Figure 1.

Metabolic pathway regulated by PKM2 in cancer cells. PKM2 exists in both a low-activity dimeric form and a high-activity tetrameric form. The less active dimeric form of PKM2 is phosphorylated by tyrosine kinases and promotes the conversion of pytuvate to lactate. In contrast, the high-activity tetrameric form promotes the conversion of pyruvate to acetyl-CoA. Intermediates of glycolysis can also enter other collateral pathways, where they are used to synthesize nucleotides, glycerol, and NADPH. G6PD, glucose-6-phosphate dehydrogenase; ROS, reactive oxygen species; RTK, receptor tyrosine kinase; TCA, tricarboxylic acid.

Figure 1.

Metabolic pathway regulated by PKM2 in cancer cells. PKM2 exists in both a low-activity dimeric form and a high-activity tetrameric form. The less active dimeric form of PKM2 is phosphorylated by tyrosine kinases and promotes the conversion of pytuvate to lactate. In contrast, the high-activity tetrameric form promotes the conversion of pyruvate to acetyl-CoA. Intermediates of glycolysis can also enter other collateral pathways, where they are used to synthesize nucleotides, glycerol, and NADPH. G6PD, glucose-6-phosphate dehydrogenase; ROS, reactive oxygen species; RTK, receptor tyrosine kinase; TCA, tricarboxylic acid.

Close modal

Pyruvate kinase (PK) is a glycolytic enzyme that catalyzes a reaction generating pyruvate and ATP from phosphoenolpyruvate (PEP) and ADP (Fig. 1). Four isoforms of PK (L, R, M1, and M2) are present in mammals. The L and R isotypes are encoded by the PKLR gene. Their expression is tissue specific and is regulated by different promoters. The L isotype is expressed in the liver, kidney, and intestine, and the R isotype is expressed in red blood cells (7–10). PKM1 and PKM2 are encoded by the PKM gene and are the products of 2 mutually exclusive alternatively spliced exons (exon 9 and exon 10, respectively; refs. 7, 11, 12): M1 is expressed in most adult differentiated tissues such as brain and muscle, whereas M2 is expressed in embryonic cells, adult stem cells, and cancer cells (3, 8, 9, 13–15). Splicing of PKM is controlled by the splicing repressors, heterogeneous nuclear ribonucleoprotein (hnRNP) A1 and A2, as well as polypyrimidine tract binding protein (PTB, also known as hnRNPI), and the expression of those repressors is upregulated by MYC oncoprotein (Fig. 2; refs. 7, 11). These proteins bind to exon 9 and repress PKM1 mRNA splicing, resulting in the inclusion of exon 10 and thereby contributing to the high levels of PKM2 expression (7, 11, 16).

Figure 2.

PKM1 and PKM2 expression after alternative splicing. The alternative exons, which encode the different segments of PKM1 and PKM2, are indicated in blue (exon 9) and red (exon 10) boxes. Mutually exclusive alternative splicing of exon 9 and exon 10 is indicated. HnRNP proteins (hnRNPA1 and hnRNPA2) and PTB (also known as hnRNPI) controlled by MYC bind to exon 9 and repress PKM1 mRNA splicing, resulting in the inclusion of exon 10, forming PKM2 mRNA. PKM2 exists in 2 oligomeric forms: a high-activity tetrameric form and a low-activity dimeric form, whereas PKM1 constitutively exists as high-activity tetrameric form. Several factors affect the switch between the dimeric and tetrameric forms. Oncoproteins, tyrosine kinase–mediated phosphorylation, and oxidative stress all promote the formation of the low-activity dimer. In contrast, fructose-1,6-P2 and serine promote the reverse situation. hnRNP, heterogeneous nuclear ribonucleoprotein.

Figure 2.

PKM1 and PKM2 expression after alternative splicing. The alternative exons, which encode the different segments of PKM1 and PKM2, are indicated in blue (exon 9) and red (exon 10) boxes. Mutually exclusive alternative splicing of exon 9 and exon 10 is indicated. HnRNP proteins (hnRNPA1 and hnRNPA2) and PTB (also known as hnRNPI) controlled by MYC bind to exon 9 and repress PKM1 mRNA splicing, resulting in the inclusion of exon 10, forming PKM2 mRNA. PKM2 exists in 2 oligomeric forms: a high-activity tetrameric form and a low-activity dimeric form, whereas PKM1 constitutively exists as high-activity tetrameric form. Several factors affect the switch between the dimeric and tetrameric forms. Oncoproteins, tyrosine kinase–mediated phosphorylation, and oxidative stress all promote the formation of the low-activity dimer. In contrast, fructose-1,6-P2 and serine promote the reverse situation. hnRNP, heterogeneous nuclear ribonucleoprotein.

Close modal

In addition to embryonic cells and adult stem cells, PKM2 is a major isoform expressed in cancer cells (3, 8, 9, 13–15). The expression of PKM2 is necessary for tumor growth (3, 15, 17–20) and a number of regulators of PKM2 expression have been reported (7, 8, 11, 16, 21–23). A recent study showed that PKM2 expression is induced by activated mTOR, which transactivates hypoxia-inducible factor 1 (HIF-1) and promotes the c-Myc-hnRNPs–mediated alternative splicing, leading to the aerobic glycolysis in tumor cells (24).

Enhanced expression of PKM2 is observed both in various cancer cell lines and in samples such as blood, serum, and stool from cancer patients (3, 9, 15, 25–27). Given that the upregulation of PKM2, concomitant with the downregulation of PKM1, is induced in skin cells within 24 hours of treatment with the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate, PKM2 expression might be an early event in carcinogenesis (28). Thus, PKM2 can be a useful biomarker for the early detection of tumors.

The expression and lower glycolytic enzyme activity of PKM2 are necessary for the Warburg effect, which provides cancer cells with selective advantages, including tumor growth and suppression of reactive oxygen species (ROS; refs. 3, 4, 15, 18) for the following 2 reasons. First is that the glycolytic pathway generates ATP more rapidly than the oxidative phosphorylation (29), allowing faster incorporation of carbon into its biomass (4, 30). Between yield and rate of ATP production, a trade-off has been reported to be present in sugar degradation by glycolysis and mitochondrial respiration. Then, glycolysis generates ATP at a high rate but low yield via massive consumption of glucose (29, 31). The second reason is that lower activity of PKM2 facilitates the production of glycolytic intermediates to enter the glycolysis branch pathways, such as glycerol synthesis and the pentose phosphate pathway, which generates NADPH to suppress ROS production and is also involved in nucleotide synthesis (Fig. 1; refs. 4, 15, 30, 32, 33). In other words, the increase in glycolysis induced by the lower activity of PKM2 can supply cancer cells with varied resources of substrates necessary for their rapid proliferation.

PKM2 exists as either a low-activity dimeric or high-activity tetrameric form, whereas PKM1 constantly exists as a high-activity tetrameric form (Figs. 1 and 2; refs. 8, 9, 34). Cancer cells predominantly express the low-activity dimeric form of PKM2 (3, 5, 6), whereas normal proliferating cells express the high-activity tetrameric form (9). Christofk and colleagues (3) and Vander Heiden and colleagues (35) from Cantley's group reported that PKM1-expressing cells showed much higher PK activity than PKM2-expressing cells; these cells consumed more oxygen, produced less lactate, and were highly sensitive to the mitochondrial ATP synthesis inhibitor, oligomycin (3). In addition, Hitosugi and colleagues reported that tyrosine phosphorylation (Tyr 105) of PKM2 disrupts the active tetrameric form of PKM2, leading to the suppression of its activity. Furthermore, PKM2-mutated cells, in which tyrosine residue 105 is replaced with a phenylalanine, had increased PK activity as observed in PKM1-expressing cells (6). Therefore, the low activity of dimeric PKM2 is a very important driver for glycolysis. In contrast, the high activity of PKM2 and PKM1 tetramers drives the tricarboxylic acid (TCA) cycle (Figs. 1 and 2; refs. 3–6).

Various factors have been reported to control the switch between the dimeric and tetrameric forms of PKM2 (5, 6, 8, 19, 36–44). For example, fructose-1,6-bisphosphate (fructose-1,6-P2), a glycolytic intermediate, binds allosterically to PKM2 and facilitates the formation of the active tetramer. Serine, which is produced from a glycolytic intermediate 3-phosphoglycerate, is also a positive regulator of PKM2 (Figs. 1 and 2A; refs. 8, 45–48). In contrast, tyrosine phosphorylation of PKM2 induces the release of fructose-1,6-P2, which causes PKM2 to convert from tetrameric form to less active dimeric form (5, 6). In addition, oncoproteins such as HPV-16 E7 and activated pp60v-src kinase dissociate the tetrameric form to yield the dimeric form (49). Furthermore, recent studies show that oxidative stress causes dissociation of the tetramer and a subsequent reduction in PKM2 activity (Figs. 1 and 2; ref. 18), and that acetylation of lysine residue within PKM2 suppresses its catalytic activity and induces the degradation by chaperone-mediated autophagy (22). In addition, it has been reported that mucin 1 phosphorylated by EGF receptor (EGFR) interacts with PKM2 and suppresses its activity (50).

A variety of molecules interact with PKM2 (5, 6, 8, 14, 18, 19, 21, 23, 24, 28, 36–45, 50–65). Many of them affect the glycolytic functions of PKM2, which directly regulate the Warburg effect. However, an increasing number of reports document the nonglycolytic functions of PKM2. In particular, the role of PKM2 in transcription is attracting attention. It has been reported that PKM2 interacts directly with the HIF-1 subunit and promotes transactivation of HIF-1 target genes (Fig. 3; ref. 21). As HIF-1 also activates the transcription of the genes encoding PKM2, cancer cells may have the positive feedback loop between PKM2 and HIF-1, which contributes to the characteristic metabolism in cancer cells.

Figure 3.

Representative nonglyclolytic functions of PKM2 in the nucleus. PHD3-dependent prolyl hydroxylated PKM2 interacts with HIF-1 and p300, enhancing HIF-1 to occupy HRE of the target genes. Nuclear-PKM2 functions as an active protein kinase capable of phosphorylating STAT3. Phosphorylated STAT3 activates Mek5 transcription via increasing its DNA-binding ability. EGFR activation induces translocation of PKM2 into the nucleus. PKM2-β-catenin complex, together with TCF/LEF, promotes expression Cyclin D1 and c-MYC. HRE, hypoxia response element; PDK1, pyruvate dehydrogenase kinase 1; PHD, prolyl hydroxylase domain.

Figure 3.

Representative nonglyclolytic functions of PKM2 in the nucleus. PHD3-dependent prolyl hydroxylated PKM2 interacts with HIF-1 and p300, enhancing HIF-1 to occupy HRE of the target genes. Nuclear-PKM2 functions as an active protein kinase capable of phosphorylating STAT3. Phosphorylated STAT3 activates Mek5 transcription via increasing its DNA-binding ability. EGFR activation induces translocation of PKM2 into the nucleus. PKM2-β-catenin complex, together with TCF/LEF, promotes expression Cyclin D1 and c-MYC. HRE, hypoxia response element; PDK1, pyruvate dehydrogenase kinase 1; PHD, prolyl hydroxylase domain.

Close modal

There have been several studies about PKM2 nuclear translocation. It is induced not only by such events as interleukin-3 stimulation and EGFR activation, which relate to cell proliferation (19, 52), but also by apoptotic stimuli such as somatostatin analogues, hydrogen peroxide (H2O2), and UV light (58). Nuclear PKM2 has been shown to activate gene transcriptions and cell proliferation (14, 19–21, 52, 61). Translocation of PKM2 into the nucleus induced by EGFR activation was reported to promote β-catenin transactivation, leading to expression of cyclinD1 and c-Myc (Fig. 3; ref. 52). Given that c-Myc upregulates transcription of hnRNPs contributing to the high PKM2/PKM1 ratio (7, 11), and that c-Myc promotes glycolysis by driving the expression of glucose transporter1 (GLUT1) and lactate dehydrogenase A (66, 67), the events induced by the translocation of PKM2 into the nucleus may be connected with a feed-forward loop to drive glycolysis.

Nuclear PKM2 has been reported to exist as a dimeric form, whereas cytoplasmic PKM2 exists as both dimeric and tetrameric form (20). In addition, the nuclear PKM2 was shown to act as a protein kinase that can phosphorylate STAT3 and thereby activate transcription of cancer-relevant genes such as Mek5 (Fig. 3; ref. 20). Taking these findings together, we speculate that PKM2 has 2 faces for conferring great benefits on cancer cells. First is that dimeric PKM2 in cytoplasm acts as a PK in which enzymatic activity is low for maintaining the glycolytic phenotype and promoting glycolytic intermediates to a collateral pathway for biosynthesis. The second is that the dimeric PKM2 translocated in the nucleus acts as an active protein kinase to phosphorylate specific nuclear proteins. Recently, many other roles of PKM2 in various condi-tions such as immunologic responses (43, 44, 63, 64), genomic instability (37), angiogenesis (57), pathogenesis (36, 41, 62), and some disease (54) have been reported. It is important to define whether those events are associated with glycolytic or nonglycolytic functions of PKM2.

CD44 is a major adhesion molecule and a cell surface marker for cancer stem cells. CD44 has been shown to be implicated in tumorigenesis as well as tumor growth and metastasis (51, 68, 69). Recently, we found that CD44 interacts with PKM2. The CD44/PKM2 interaction suppresses PKM2 enzymatic activity via tyrosine phosphorylation, thereby promoting glycolysis and increasing the flux to the pentose phosphate pathway (PPP) in glycolytic cancer cells that are either p53 dysfunctional or hypoxic (Fig. 4; ref. 51). CD44 ablation enhances mitochondrial respiration through metabolic shift from glycolysis, which may suppress GLUT1 expression, thereby reducing glucose uptake, and subsequent PPP flux. Such metabolic changes induced by CD44 ablation lead to the downregulation of reduced glutathione (GSH) synthesis in cells, along with a consequent increase in ROS accumulation (Fig. 4; ref. 51). Interestingly, PKM2 activity is inhibited by oxidative stress as well as tyrosine phosphorylation (18). Oxidative stress induces the oxidization of Cys358 within PKM2, which promotes glycolysis and PPP flux, leading to the production of GSH and consequent ROS depletion (18, 70, 71). Thus, cancer cells have multiple mechanisms for avoiding ROS accumulation, which gives them a survival advantage in terms of tumor growth and therapeutic resistance (18, 51, 72).

Figure 4.

Schematic diagram of CD44/PKM2 interaction-regulating GSH production in glycolytic cancer cells. The CD44/PKM2 interaction suppresses PKM2 activity via tyrosine phosphorylation and promotes glycolysis. Promotion of glycolysis and suppression of the TCA cycle are maintained by the CD44/PKM2 interaction, which is related to increased glucose uptake mediated by upregulated GLUT1. Increasing glucose uptake and subsequent PPP flux that produces NADPH contribute to increased GSH production and reduced ROS accumulation. CD44s, standard isoform of CD44, which lacks all variant exons; CD44v, splice variant isoforms of CD44, which contain variable exons; GSH, glutathione; RTK, receptor tyrosine kinase.

Figure 4.

Schematic diagram of CD44/PKM2 interaction-regulating GSH production in glycolytic cancer cells. The CD44/PKM2 interaction suppresses PKM2 activity via tyrosine phosphorylation and promotes glycolysis. Promotion of glycolysis and suppression of the TCA cycle are maintained by the CD44/PKM2 interaction, which is related to increased glucose uptake mediated by upregulated GLUT1. Increasing glucose uptake and subsequent PPP flux that produces NADPH contribute to increased GSH production and reduced ROS accumulation. CD44s, standard isoform of CD44, which lacks all variant exons; CD44v, splice variant isoforms of CD44, which contain variable exons; GSH, glutathione; RTK, receptor tyrosine kinase.

Close modal

Cancer-specific metabolism, which is associated with therapeutic resistance, is an attractive target for cancer therapy (30, 66, 67, 73–78). As outlined above, PKM2 plays many important roles in metabolism and signals in cancer cells and, thereby, can be an ideal therapeutic target. The RNA interference and the peptide aptamers which ablate PKM2 have been reported to elicit anticancer effects, such as the impairment of tumor growth, induction of apoptotic cell death, and increasing sensitivity to chemotherapy (3, 17, 56, 79, 80). Small-molecule inhibitors of PKM2 have already been identified, and these inhibitors suppress glycolysis and cause cell death. However, therapies targeting PKM2 expression are problematic. One problem is that PKM2 is also expressed in some normal tissues (8). The other is that PKM2 knockdown by short hairpin RNA does not completely disrupt cancer cell proliferation; nevertheless, it induces near-complete depletion of PKM2 activity (77). Thus, the compounds that activate the catalytic function of PKM2 may have a role as therapeutic modalities (32, 33, 77, 81). Given that the activity of PKM2 expressed in normal tissues is high, whereas that in cancer cells is low (9), such activators may inhibit glycolysis and proliferation in cancer cells with less toxic effects in normal cells. PKM2 activators show a similar effect of fructose-1,6-P2, which induces tetrameric formation of PKM2 (33). Because nucleic PKM2 exists as a dimer, PKM2 activators have a potential to prevent PKM2 from moving into the nucleus and thereby suppress functions of nucleic PKM2. In other words, PKM2 activators may be capable of inhibiting both glycolytic and nonglycolytic functions of PKM2.

Inhibition of glycolytic function of PKM2 can suppress glycolysis, leading to an increase in ROS production and a decreasing supply of varied resources of substrates necessary for rapid cancer cell proliferation. Inhibition of nonglycolytic function of PKM2 can suppress the activation of cancer-relevant genes such as Mek5, c-Myc, and various HIF-1 target genes (Fig. 3). Further studies are required to ensure their suitability for cancer therapy.

Our group reported that CD44 ablation increases the enzyme activity of PKM2, thereby inducing metabolic changes, including a shift from glycolysis to TCA cycle, leading to suppression of glucose uptake mediated downregulation of GLUT1 expression (51). Such metabolic changes induced by CD44 ablation reduce the flux to PPP and consequently accumulate ROS (Fig. 4). This sensitizes glycolytic cancer cells such as p53-mutated cells and hypoxic cells to anticancer drugs. Thus, our data suggest that indirect activation of PKM2 may have a synergistic effect when used in combination with existing therapies.

Both the glycolytic and nonglycolytic functions of PKM2 provide cancer cells with growth and survival advantages. PKM2 expression was shown to be involved in early tumorigenesis (28) and can be detected in the blood and stool of cancer patients (9, 82); furthermore, increases in PKM2 levels were reported to correlate with tumor size and stage (9). As described in another article in this CCR Focus section by Yang and colleagues, mutations of IDH1 and IDH2 are also reported to be easily detectable using small amounts of tumor samples (83). Accordingly, these enzymes involved in cancer metabolism can be useful biomarkers.

It was recently shown that the microenvironment also confers metabolic heterogeneity on cancer tissues (15, 77). Such metabolic heterogeneity may be caused by the differences in the supply of nutrients and oxygen because each cancer cell is located at a different distance from the blood vessels (77). Acetylation of PKM2, which inhibits its catalytic activity, is triggered by high glucose levels (22, 30, 84). PKM2 acts as a metabolic sensor in a manner that is dependent upon the glucose supply (79). The regulation of HIF-1 and PKM2 also differs according to the degree of hypoxia (21, 85). In addition, Hamanaka and colleagues suggested that PKM2 inhibitors suppress ATP production under severely hypoxic conditions; however, PKM2 activators would increase oxidative damage under moderately hypoxic conditions (30). Interestingly, PKM2-overexpressing stromal cells have been reported to supply recycled chemical building blocks such as lipids or nucleotides via autophagy, increase ketone body secretion, and fuel mitochondrial respiration of adjacent cancer cells (86).

In conclusion, the status of PKM2 is regulated by both intrinsic and extrinsic factors. Through the glycolytic and nonglycolytic functions, PKM2 contributes to the malignant phenotype of cancer cells, suggesting it could be an excellent target for cancer therapy. However, PKM2 has multiple faces and the intracellular events elicited by PKM2 are far more complicated than previously assumed. Furthermore, the effects of targeting PKM2 on normal cells have not been fully assessed. Therefore, further studies are needed before inhibitors and activators of PKM2 can be used as therapeutic interventions.

H. Saya, commercial research grants, Kyowa Hakko Kirin Co. Ltd and Daiichi Sankyo Co. Ltd. No potential conflicts of interest were disclosed by the other authors.

Conception and design: M. Tamada, H. Saya

Development of methodology: M. Tamada

Acquisition of data (provided animals, acquired and managed patients, provided facilities, etc.): M. Tamada

Analysis and interpretation of data (e.g., statistical analysis, biostatistics, computational analysis): M. Tamada

Writing, review, and/or revision of the manuscript: M. Tamada, M. Suematsu, H. Saya

Administrative, technical, or material support (i.e., reporting or organizing data, constructing databases): M. Tamada

The authors thank members of the division of Gene Regulation, IAMR, School of Medicine, Keio University, for their important suggestions, and K. Arai for help with preparation of the manuscript.

This work was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (H. Saya), and the Global COE Program, MEXT, Japan (M. Tamada).

1.
Warburg
O
,
Wind
F
,
Negelein
E
. 
The metabolism of tumors in the body
.
J Gen Physiol
1927
;
8
:
519
30
.
2.
Gatenby
RA
,
Gillies
RJ
. 
Why do cancers have high aerobic glycolysis?
Nat Rev
2004
;
4
:
891
9
.
3.
Christofk
HR
,
Vander Heiden
MG
,
Harris
MH
,
Ramanathan
A
,
Gerszten
RE
,
Wei
R
, et al
The M2 splice isoform of pyruvate kinase is important for cancer metabolism and tumour growth
.
Nature
2008
;
452
:
230
3
.
4.
Vander Heiden
MG
,
Cantley
LC
,
Thompson
CB
. 
Understanding the Warburg effect: the metabolic requirements of cell proliferation
.
Science
2009
;
324
:
1029
33
.
5.
Christofk
HR
,
Vander Heiden
MG
,
Wu
N
,
Asara
JM
,
Cantley
LC
. 
Pyruvate kinase M2 is a phosphotyrosine-binding protein
.
Nature
2008
;
452
:
181
6
.
6.
Hitosugi
T
,
Kang
S
,
Vander Heiden
MG
,
Chung
TW
,
Elf
S
,
Lythgoe
K
, et al
Tyrosine phosphorylation inhibits PKM2 to promote the Warburg effect and tumor growth
.
Sci Signal
2009
;
2
:
ra73
.
7.
Clower
CV
,
Chatterjee
D
,
Wang
Z
,
Cantley
LC
,
Vander Heiden
MG
,
Krainer
AR
. 
The alternative splicing repressors hnRNP A1/A2 and PTB influence pyruvate kinase isoform expression and cell metabolism
.
Proc Natl Acad Sci U S A
2010
;
107
:
1894
9
.
8.
Mazurek
S
. 
Pyruvate kinase type M2: a key regulator of the metabolic budget system in tumor cells
.
Int J Biochem Cell Biol
2011
;
43
:
969
80
.
9.
Mazurek
S
,
Boschek
CB
,
Hugo
F
,
Eigenbrodt
E
. 
Pyruvate kinase type M2 and its role in tumor growth and spreading
.
Semin Cancer Biol
2005
;
15
:
300
8
.
10.
Noguchi
T
,
Yamada
K
,
Inoue
H
,
Matsuda
T
,
Tanaka
T
. 
The L- and R-type isozymes of rat pyruvate kinase are produced from a single gene by use of different promoters
.
J Biol Chem
1987
;
262
:
14366
71
.
11.
David
CJ
,
Chen
M
,
Assanah
M
,
Canoll
P
,
Manley
JL
. 
HnRNP proteins controlled by c-Myc deregulate pyruvate kinase mRNA splicing in cancer
.
Nature
2010
;
463
:
364
8
.
12.
Noguchi
T
,
Inoue
H
,
Tanaka
T
. 
The M1- and M2-type isozymes of rat pyruvate kinase are produced from the same gene by alternative RNA splicing
.
J Biol Chem
1986
;
261
:
13807
12
.
13.
Bluemlein
K
,
Gruning
NM
,
Feichtinger
RG
,
Lehrach
H
,
Kofler
B
,
Ralser
M
. 
No evidence for a shift in pyruvate kinase PKM1 to PKM2 expression during tumorigenesis
.
Oncotarget
2011
;
2
:
393
400
.
14.
Lee
J
,
Kim
HK
,
Han
YM
,
Kim
J
. 
Pyruvate kinase isozyme type M2 (PKM2) interacts and cooperates with Oct-4 in regulating transcription
.
Int J Biochem Cell Biol
2008
;
40
:
1043
54
.
15.
Cairns
RA
,
Harris
IS
,
Mak
TW
. 
Regulation of cancer cell metabolism
.
Nat Rev
2011
;
11
:
85
95
.
16.
Chen
M
,
David
CJ
,
Manley
JL
. 
Concentration-dependent control of pyruvate kinase M mutually exclusive splicing by hnRNP proteins
.
Nat Struct Mol Biol
2012
;
19
:
346
54
.
17.
Goldberg
MS
,
Sharp
PA
. 
Pyruvate kinase M2-specific siRNA induces apoptosis and tumor regression
.
J Exp Med
2012
;
209
:
217
24
.
18.
Anastasiou
D
,
Poulogiannis
G
,
Asara
JM
,
Boxer
MB
,
Jiang
JK
,
Shen
M
, et al
Inhibition of pyruvate kinase M2 by reactive oxygen species contributes to cellular antioxidant responses
.
Science
2011
;
334
:
1278
83
.
19.
Hoshino
A
,
Hirst
JA
,
Fujii
H
. 
Regulation of cell proliferation by interleukin-3-induced nuclear translocation of pyruvate kinase
.
J Biol Chem
2007
;
282
:
17706
11
.
20.
Gao
X
,
Wang
H
,
Yang
JJ
,
Liu
X
,
Liu
ZR
. 
Pyruvate kinase M2 regulates gene transcription by acting as a protein kinase
.
Mol Cell
2012
;
45
:
598
609
.
21.
Luo
W
,
Hu
H
,
Chang
R
,
Zhong
J
,
Knabel
M
,
O'Meally
R
, et al
Pyruvate kinase M2 is a PHD3-stimulated coactivator for hypoxia-inducible factor 1
.
Cell
2011
;
145
:
732
44
.
22.
Lv
L
,
Li
D
,
Zhao
D
,
Lin
R
,
Chu
Y
,
Zhang
H
, et al
Acetylation targets the M2 isoform of pyruvate kinase for degradation through chaperone-mediated autophagy and promotes tumor growth
.
Mol Cell
2011
;
42
:
719
30
.
23.
Panasyuk
G
,
Espeillac
C
,
Chauvin
C
,
Pradelli
LA
,
Horie
Y
,
Suzuki
A
, et al
PPARgamma contributes to PKM2 and HK2 expression in fatty liver
.
Nat Commun
2012
;
3
:
672
.
24.
Sun
Q
,
Chen
X
,
Ma
J
,
Peng
H
,
Wang
F
,
Zha
X
, et al
Mammalian target of rapamycin up-regulation of pyruvate kinase isoenzyme type M2 is critical for aerobic glycolysis and tumor growth
.
Proc Natl Acad Sci U S A
2011
;
108
:
4129
34
.
25.
Luftner
D
,
Mesterharm
J
,
Akrivakis
C
,
Geppert
R
,
Petrides
PE
,
Wernecke
KD
, et al
Tumor type M2 pyruvate kinase expression in advanced breast cancer
.
Anticancer Res
2000
;
20
:
5077
82
.
26.
Schneider
J
,
Neu
K
,
Grimm
H
,
Velcovsky
HG
,
Weisse
G
,
Eigenbrodt
E
. 
Tumor M2-pyruvate kinase in lung cancer patients: immunohistochemical detection and disease monitoring
.
Anticancer Res
2002
;
22
:
311
8
.
27.
Cerwenka
H
,
Aigner
R
,
Bacher
H
,
Werkgartner
G
,
el-Shabrawi
A
,
Quehenberger
F
, et al
TUM2-PK (pyruvate kinase type tumor M2), CA19–9 and CEA in patients with benign, malignant and metastasizing pancreatic lesions
.
Anticancer Res
1999
;
19
:
849
51
.
28.
Wittwer
JA
,
Robbins
D
,
Wang
F
,
Codarin
S
,
Shen
X
,
Kevil
CG
, et al
Enhancing mitochondrial respiration suppresses tumor promoter TPA-induced PKM2 expression and cell transformation in skin epidermal JB6 cells
.
Cancer Prevent Res
2011
;
4
:
1476
84
.
29.
Pfeiffer
T
,
Schuster
S
,
Bonhoeffer
S
. 
Cooperation and competition in the evolution of ATP-producing pathways
.
Science
2001
;
292
:
504
7
.
30.
Hamanaka
RB
,
Chandel
NS
. 
Targeting glucose metabolism for cancer therapy
.
J Exp Med
2012
;
209
:
211
5
.
31.
Vazquez
A
,
Liu
J
,
Zhou
Y
,
Oltvai
ZN
. 
Catabolic efficiency of aerobic glycolysis: the Warburg effect revisited
.
BMC Syst Biol
2010
;
4
:
58
.
32.
Jiang
JK
,
Boxer
MB
,
Vander Heiden
MG
,
Shen
M
,
Skoumbourdis
AP
,
Southall
N
, et al
Evaluation of thieno[3,2-b]pyrrole[3,2-d]pyridazinones as activators of the tumor cell specific M2 isoform of pyruvate kinase
.
Bioorg Med Chem Lett
2010
;
20
:
3387
93
.
33.
Boxer
MB
,
Jiang
JK
,
Vander Heiden
MG
,
Shen
M
,
Skoumbourdis
AP
,
Southall
N
, et al
Evaluation of substituted N, N'-diarylsulfonamides as activators of the tumor cell specific M2 isoform of pyruvate kinase
.
J Med Chem
2010
;
53
:
1048
55
.
34.
Dang
CV
. 
PKM2 tyrosine phosphorylation and glutamine metabolism signal a different view of the Warburg effect
.
Sci Signal
2009
;
2
:
pe75
.
35.
Vander Heiden
MG
,
Locasale
JW
,
Swanson
KD
,
Sharfi
H
,
Heffron
GJ
,
Amador-Noguez
D
, et al
Evidence for an alternative glycolytic pathway in rapidly proliferating cells
.
Science
2010
;
329
:
1492
9
.
36.
Wu
X
,
Zhou
Y
,
Zhang
K
,
Liu
Q
,
Guo
D
. 
Isoform-specific interaction of pyruvate kinase with hepatitis C virus NS5B
.
FEBS Lett
2008
;
582
:
2155
60
.
37.
Shimada
N
,
Shinagawa
T
,
Ishii
S
. 
Modulation of M2-type pyruvate kinase activity by the cytoplasmic PML tumor suppressor protein
.
Gens Cells
2008
;
13
:
245
54
.
38.
Mazurek
S
,
Drexler
HC
,
Troppmair
J
,
Eigenbrodt
E
,
Rapp
UR
. 
Regulation of pyruvate kinase type M2 by A-Raf: a possible glycolytic stop or go mechanism
.
Anticancer Res
2007
;
27
:
3963
71
.
39.
Siwko
S
,
Mochly-Rosen
D
. 
Use of a novel method to find substrates of protein kinase C delta identifies M2 pyruvate kinase
.
Int J Biochem Cell Biol
2007
;
39
:
978
87
.
40.
LeMellay
V
,
Houben
R
,
Troppmair
J
,
Hagemann
C
,
Mazurek
S
,
Frey
U
, et al
Regulation of glycolysis by Raf protein serine/threonine kinases
.
Adv Enzyme Regul
2002
;
42
:
317
32
.
41.
Zwerschke
W
,
Mazurek
S
,
Massimi
P
,
Banks
L
,
Eigenbrodt
E
,
Jansen-Durr
P
. 
Modulation of type M2 pyruvate kinase activity by the human papillomavirus type 16 E7 oncoprotein
.
Proc Natl Acad Sci U S A
1999
;
96
:
1291
6
.
42.
Presek
P
,
Glossmann
H
,
Eigenbrodt
E
,
Schoner
W
,
Rubsamen
H
,
Friis
RR
, et al
Similarities between a phosphoprotein (pp60src)-associated protein kinase of Rous sarcoma virus and a cyclic adenosine 3′:5′-monophosphate-independent protein kinase that phosphorylates pyruvate kinase type M2
.
Cancer Res
1980
;
40
:
1733
41
.
43.
Ryu
H
,
Walker
JK
,
Kim
S
,
Koo
N
,
Barak
LS
,
Noguchi
T
, et al
Regulation of M2-type pyruvate kinase mediated by the high-affinity IgE receptors is required for mast cell degranulation
.
Br J Pharmacol
2008
;
154
:
1035
46
.
44.
Zhang
Z
,
Liu
Q
,
Che
Y
,
Yuan
X
,
Dai
L
,
Zeng
B
, et al
Antigen presentation by dendritic cells in tumors is disrupted by altered metabolism that involves pyruvate kinase M2 and its interaction with SOCS3
.
Cancer Res
2010
;
70
:
89
98
.
45.
Ward
PS
,
Thompson
CB
. 
Metabolic reprogramming: a cancer hallmark even warburg did not anticipate
.
Cancer Cell
2012
;
21
:
297
308
.
46.
Ashizawa
K
,
Willingham
MC
,
Liang
CM
,
Cheng
SY
. 
In vivo regulation of monomer-tetramer conversion of pyruvate kinase subtype M2 by glucose is mediated via fructose 1,6-bisphosphate
.
J Biol Chem
1991
;
266
:
16842
6
.
47.
Eigenbrodt
E
,
Leib
S
,
Kramer
W
,
Friis
RR
,
Schoner
W
. 
Structural and kinetic differences between the M2 type pyruvate kinases from lung and various tumors
.
Biomed Biochim Acta
1983
;
42
:
S278
82
.
48.
Ye
J
,
Mancuso
A
,
Tong
X
,
Ward
PS
,
Fan
J
,
Rabinowitz
JD
, et al
Pyruvate kinase M2 promotes de novo serine synthesis to sustain mTORC1 activity and cell proliferation
.
Proc Natl Acad Sci U S A
2012
;
109
:
6904
9
.
49.
Mazurek
S
,
Grimm
H
,
Boschek
CB
,
Vaupel
P
,
Eigenbrodt
E
. 
Pyruvate kinase type M2: a crossroad in the tumor metabolome
.
Br J Nutr
2002
;
87
Suppl 1
:
S23
9
.
50.
Kosugi
M
,
Ahmad
R
,
Alam
M
,
Uchida
Y
,
Kufe
D
. 
MUC1-C oncoprotein regulates glycolysis and pyruvate kinase M2 activity in cancer cells
.
PLoS One
2011
;
6
:
e28234
.
51.
Tamada
M
,
Nagano
O
,
Tateyama
S
,
Ohmura
M
,
Yae
T
,
Ishimoto
T
, et al
Modulation of glucose metabolism by CD44 contributes to antioxidant status and drug resistance in cancer cells
.
Cancer Res
2012
;
72
:
1438
48
.
52.
Yang
W
,
Xia
Y
,
Ji
H
,
Zheng
Y
,
Liang
J
,
Huang
W
, et al
Nuclear PKM2 regulates beta-catenin transactivation upon EGFR activation
.
Nature
2011
;
480
:
118
22
.
53.
Diaz-Jullien
C
,
Moreira
D
,
Sarandeses
CS
,
Covelo
G
,
Barbeito
P
,
Freire
M
. 
The M2-type isoenzyme of pyruvate kinase phosphorylates prothymosin alpha in proliferating lymphocytes
.
Biochim Biophys Acta
2011
;
1814
:
355
65
.
54.
Gupta
V
,
Bamezai
RN
. 
Human pyruvate kinase M2: a multifunctional protein
.
Protein Sci
2010
;
19
:
2031
44
.
55.
Spoden
GA
,
Morandell
D
,
Ehehalt
D
,
Fiedler
M
,
Jansen-Durr
P
,
Hermann
M
, et al
The SUMO-E3 ligase PIAS3 targets pyruvate kinase M2
.
J Cell Biochem
2009
;
107
:
293
302
.
56.
Spoden
GA
,
Mazurek
S
,
Morandell
D
,
Bacher
N
,
Ausserlechner
MJ
,
Jansen-Durr
P
, et al
Isotype-specific inhibitors of the glycolytic key regulator pyruvate kinase subtype M2 moderately decelerate tumor cell proliferation
.
Int J Cancer
2008
;
123
:
312
21
.
57.
Duan
HF
,
Hu
XW
,
Chen
JL
,
Gao
LH
,
Xi
YY
,
Lu
Y
, et al
Antitumor activities of TEM8-Fc: an engineered antibody-like molecule targeting tumor endothelial marker 8
.
J Natl Cancer Inst
2007
;
99
:
1551
5
.
58.
Stetak
A
,
Veress
R
,
Ovadi
J
,
Csermely
P
,
Keri
G
,
Ullrich
A
. 
Nuclear translocation of the tumor marker pyruvate kinase M2 induces programmed cell death
.
Cancer Res
2007
;
67
:
1602
8
.
59.
Li
Y
,
Chang
Y
,
Zhang
L
,
Feng
Q
,
Liu
Z
,
Zhang
Y
, et al
High glucose upregulates pantothenate kinase 4 (PanK4) and thus affects M2-type pyruvate kinase (Pkm2)
.
Mol Cell Biochem
2005
;
277
:
117
25
.
60.
Garcia-Gonzalo
FR
,
Cruz
C
,
Munoz
P
,
Mazurek
S
,
Eigenbrodt
E
,
Ventura
F
, et al
Interaction between HERC1 and M2-type pyruvate kinase
.
FEBS Lett
2003
;
539
:
78
84
.
61.
Ignacak
J
,
Stachurska
MB
. 
The dual activity of pyruvate kinase type M2 from chromatin extracts of neoplastic cells
.
Comp Biochem Physiol B Biochem Mol Biol
2003
;
134
:
425
33
.
62.
Mazurek
S
,
Zwerschke
W
,
Jansen-Durr
P
,
Eigenbrodt
E
. 
Effects of the human papilloma virus HPV-16 E7 oncoprotein on glycolysis and glutaminolysis: role of pyruvate kinase type M2 and the glycolytic-enzyme complex
.
Biochem J
2001
;
356
:
247
56
.
63.
Oak
MH
,
Cheong
H
,
Kim
KM
. 
Activation of Fc epsilon RI inhibits the pyruvate kinase through direct interaction with the gamma-chain
.
Int Arch Allergy Immunol
1999
;
119
:
95
100
.
64.
Williams
JM
,
Chen
GC
,
Zhu
L
,
Rest
RF
. 
Using the yeast two-hybrid system to identify human epithelial cell proteins that bind gonococcal Opa proteins: intracellular gonococci bind pyruvate kinase via their Opa proteins and require host pyruvate for growth
.
Mol Microbiol
1998
;
27
:
171
86
.
65.
Kato
H
,
Fukuda
T
,
Parkison
C
,
McPhie
P
,
Cheng
SY
. 
Cytosolic thyroid hormone-binding protein is a monomer of pyruvate kinase
.
Proc Natl Acad Sci U S A
1989
;
86
:
7861
5
.
66.
Munoz-Pinedo
C
,
El Mjiyad
N
,
Ricci
JE
. 
Cancer metabolism: current perspectives and future directions
.
Cell Death Dis
2012
;
3
:
e248
.
67.
Dang
CV
,
Le
A
,
Gao
P
. 
MYC-induced cancer cell energy metabolism and therapeutic opportunities
.
Clinical Cancer Res
2009
;
15
:
6479
83
.
68.
Nagano
O
,
Saya
H
. 
Mechanism and biological significance of CD44 cleavage
.
Cancer Sci
2004
;
95
:
930
5
.
69.
Visvader
JE
,
Lindeman
GJ
. 
Cancer stem cells in solid tumours: accumulating evidence and unresolved questions
.
Nat Rev
2008
;
8
:
755
68
.
70.
Gruning
NM
,
Ralser
M
. 
Cancer: sacrifice for survival
.
Nature
2011
;
480
:
190
1
.
71.
Hamanaka
RB
,
Chandel
NS
. 
Cell biology. Warburg effect and redox balance
.
Science
2011
;
334
:
1219
20
.
72.
Ishimoto
T
,
Nagano
O
,
Yae
T
,
Tamada
M
,
Motohara
T
,
Oshima
H
, et al
CD44 variant regulates redox status in cancer cells by stabilizing the xCT subunit of system xc(-) and thereby promotes tumor growth
.
Cancer cell
2011
;
19
:
387
400
.
73.
Meijer
TWH
,
Kaanders
JHAM
,
Span
PN
,
Bussink
J
. 
Targeting hypoxia, HIF-1 and tumor glucose metabolism to improve radiotherapy efficacy
.
Clin Cancer Res
2012
;
18
:
5585
94
.
74.
Jerby
L
,
Ruppin
E
. 
Predicting drug targets and biomarkers of cancer via genome-scale metabolic modeling
.
Clin Cancer Res
2012
;
18
:
5572
84
.
75.
Dang
CV
,
Hamaker
M
,
Sun
P
,
Le
A
,
Gao
P
. 
Therapeutic targeting of cancer cell metabolism
.
J Mol Med
2011
;
89
:
205
12
.
76.
Iaccarino
I
,
Martins
LM
. 
Therapeutic targets in cancer cell metabolism and death
.
Cell Death Differ
2011
;
18
:
565
70
.
77.
VanderHeiden
MG
. 
Targeting cancer metabolism: a therapeutic window opens
.
Nat Rev Drug Discov
2011
;
10
:
671
84
.
78.
Bonnet
S
,
Archer
SL
,
Allalunis-Turner
J
,
Haromy
A
,
Beaulieu
C
,
Thompson
R
, et al
A mitochondria-K+ channel axis is suppressed in cancer and its normalization promotes apoptosis and inhibits cancer growth
.
Cancer Cell
2007
;
11
:
37
51
.
79.
Spoden
GA
,
Rostek
U
,
Lechner
S
,
Mitterberger
M
,
Mazurek
S
,
Zwerschke
W
. 
Pyruvate kinase isoenzyme M2 is a glycolytic sensor differentially regulating cell proliferation, cell size and apoptotic cell death dependent on glucose supply
.
Exp Cell Res
2009
;
315
:
2765
74
.
80.
Guo
W
,
Zhang
Y
,
Chen
T
,
Wang
Y
,
Xue
J
,
Zhang
Y
, et al
Efficacy of RNAi targeting of pyruvate kinase M2 combined with cisplatin in a lung cancer model
.
J Cancer Res Clin Oncol
2011
;
137
:
65
72
.
81.
Walsh
MJ
,
Brimacombe
KR
,
Veith
H
,
Bougie
JM
,
Daniel
T
,
Leister
W
, et al
2-Oxo-N-aryl-1,2,3,4-tetrahydroquinoline-6-sulfonamides as activators of the tumor cell specific M2 isoform of pyruvate kinase
.
Bioorg Med Chem Lett
2011
;
21
:
6322
7
.
82.
Hathurusinghe
HR
,
Goonetilleke
KS
,
Siriwardena
AK
. 
Current status of tumor M2 pyruvate kinase (tumor M2-PK) as a biomarker of gastrointestinal malignancy
.
Ann Surg Oncol
2007
;
14
:
2714
20
.
83.
Yang
H
,
Ye
D
,
Guan
K-L
,
Xiong
Y
. 
IDH1 and IDH2 mutations in tumorigenesis: mechanistic insights and clinical perspectives
.
Clin Cancer Res
2012
;
18
:
5562
71
.
84.
Macintyre
AN
,
Rathmell
JC
. 
PKM2 and the tricky balance of growth and energy in cancer
.
Molecular cell
2011
;
42
:
713
4
.
85.
Tennant
DA
. 
PK-M2 makes cells sweeter on HIF1
.
Cell
2011
;
145
:
647
9
.
86.
Chiavarina
B
,
Whitaker-Menezes
D
,
Martinez-Outschoorn
UE
,
Witkiewicz
AK
,
Birbe
RC
,
Howell
A
, et al
Pyruvate kinase expression (PKM1 and PKM2) in cancer-associated fibroblasts drives stromal nutrient production and tumor growth
.
Cancer Biol Ther
2011
;
12
:
1101
13
.