Role of isoenzyme M2 of pyruvate kinase in urothelial tumorigenesis

Alternative splicing in bladder cancer: potential strategies for cancer diagnosis, prognosis, and treatment

Bladder cancer is the most common malignancy of the urinary tract worldwide. The therapeutic options to tackle this disease comprise surgery, intravesical or systemic chemotherapy, and immunotherapy. Unfortunately, a wide number of patients ultimately become resistant to these treatments and develop aggressive metastatic disease, presenting a poor prognosis. Therefore, the identification of novel therapeutic approaches to tackle this devastating pathology is urgently needed. However, a significant limitation is that the progression and drug response of bladder cancer is strongly associated with its intrinsic molecular heterogeneity. In this sense, RNA splicing is recently gaining importance as a critical hallmark of cancer since can have a significant clinical value. In fact, a profound dysregulation of the splicing process has been reported in bladder cancer, especially in the expression of certain key splicing variants and circular RNAs with a potential clinical value as diagnostic/prognostic biomarkers or therapeutic targets in this pathology. Indeed, some authors have already evidenced a profound antitumor effect by targeting some splicing factors (e.g., PTBP1), mRNA splicing variants (e.g., PKM2, HYAL4-v1), and circular RNAs (e.g., circITCH, circMYLK), which illustrates new possibilities to significantly improve the management of this pathology. This review represents the first detailed overview of the splicing process and its alterations in bladder cancer, and highlights opportunities for the development of novel diagnostic/prognostic biomarkers and their clinical potential for the treatment of this devastating cancer type. This article is categorized under: RNA Processing > Splicing Regulation/Alternative Splicing RNA in Disease and Development > RNA in Disease.

Glucose Metabolism Reprogramming in Bladder Cancer: Hexokinase 2 (HK2) as Prognostic Biomarker and Target for Bladder Cancer Therapy

Proliferating cancer cells are able to reprogram their energy metabolism, favouring glycolysis even in the presence of oxygen and fully functioning mitochondria. Research is needed to validate the glycolysis-related proteins as prognostic/predictive biomarkers in urothelial bladder carcinoma (UBC), a malignancy tagged by high recurrence rates and poor response to chemotherapy. Here, we assessed GLUT1, HK2, PFKL, PKM2, phospho-PDH, and LDHA immunoexpression in 76 UBC samples, differentiating among urothelial, fibroblast, and endothelial cells and among normoxic versus hypoxic areas. We additionally studied the functional effects of the HK2 inhibitor 2-deoxy-D-glucose (2DG) in "in vitro" and "in vivo" preclinical UBC models. We showed that the expression of the glycolysis-related proteins is associated with UBC aggressiveness and poor prognosis. HK2 remained as an independent prognostic factor for disease-free and overall survival. 2DG decreased the UBC cell's viability, proliferation, migration, and invasion; the inhibition of cell cycle progression and apoptosis occurrence was also verified. A significant reduction in tumour growth and blood vessel formation upon 2DG treatment was observed in the chick chorioallantoic membrane assay. 2DG potentiated the cisplatin-induced inhibition of cell viability in a cisplatin-resistant subline. This study highlights HK2 as a prognostic biomarker for UBC patients and demonstrates the potential benefits of using 2DG as a glycolysis inhibitor. Future studies should focus on integrating 2DG into chemotherapy design, as an attempt to overcome cisplatin resistance.

Single-Cell FISH Analysis Reveals Distinct Shifts in PKM Isoform Populations during Drug Resistance Acquisition

The Warburg effect, i.e., the utilization of glycolysis under aerobic conditions, is recognized as a survival advantage of cancer cells. However, how the glycolytic activity is affected during drug resistance acquisition has not been explored at single-cell resolution. Because the relative ratio of the splicing isoform of pyruvate kinase M (PKM), PKM2/PKM1, can be used to estimate glycolytic activity, we utilized a single-molecule fluorescence in situ hybridization (SM-FISH) method to simultaneously quantify the mRNA levels of PKM1 and PKM2. Treatment of HCT116 cells with gefitinib (GE) resulted in two distinct populations of cells. However, as cells developed GE resistance, the GE-sensitive population with reduced PKM2 expression disappeared, and GE-resistant cells (Res) demonstrated enhanced PKM1 expression and a tightly regulated PKM2/PKM1 ratio. Our data suggest that maintaining an appropriate PKM2 level is important for cell survival upon GE treatment, whereas increased PKM1 expression becomes crucial in GE Res. This approach demonstrates the importance of single-cell-based analysis for our understanding of cancer cell metabolic responses to drugs, which could aid in the design of treatment strategies for drug-resistant cancers.

PKM2 Is Essential for Bladder Cancer Growth and Maintenance

Pyruvate kinase M2 (PKM2) has been shown to promote tumorigenesis by facilitating the Warburg effect and enhancing the activities of oncoproteins. However, this paradigm has recently been challenged by studies in which the absence of PKM2 failed to inhibit and instead accelerated tumorigenesis in mouse models. These results seem inconsistent with the fact that most human tumors overexpress PKM2. To further elucidate the role of PKM2 in tumorigenesis, we investigated the effect of PKM2 knockout in oncogenic HRAS-driven urothelial carcinoma. While PKM2 ablation in mouse urothelial cells did not affect tumor initiation, it impaired the growth and maintenance of HRAS-driven tumors. Chemical inhibition of PKM2 recapitulated these effects. Both conditions substantially reduced complex formation of PKM2 with STAT3, their nuclear translocation, and HIF1α- and VEGF-related angiogenesis. The reduction in nuclear STAT3 in the absence of PKM2 also correlated with decreased autophagy and increased apoptosis. Time-controlled, inducible PKM2 overexpression in simple urothelial hyperplasia did not trigger tumorigenesis, while overexpression of PKM2, but not PKM1, in nodular urothelial hyperplasia with angiogenesis strongly accelerated tumorigenesis. Finally, in human patients, PKM2 was overexpressed in low-grade nonmuscle-invasive and high-grade muscle-invasive bladder cancer. Based on these data, PKM2 is not required for tumor initiation but is essential for tumor growth and maintenance by enhancing angiogenesis and metabolic addiction. The PKM2-STAT3-HIF1α/VEGF signaling axis may play a critical role in bladder cancer and may serve as an actionable therapeutic target.

SIGNIFICANCE

Genetic manipulation and pharmacologic inhibition of PKM2 in mouse urothelial lesions highlight its essential role in promoting angiogenesis and metabolic addiction, events indispensable for tumor growth and maintenance.

Current Development and Application of Anaerobic Glycolytic Enzymes in Urothelial Cancer

Urothelial cancer is a malignant tumor with metastatic ability and high mortality. Malignant tumors of the urinary system include upper tract urothelial cancer and bladder cancer. In addition to typical genetic alterations and epigenetic modifications, metabolism-related events also occur in urothelial cancer. This metabolic reprogramming includes aberrant expression levels of genes, metabolites, and associated networks and pathways. In this review, we summarize the dysfunctions of glycolytic enzymes in urothelial cancer and discuss the relevant phenotype and signal transduction. Moreover, we describe potential prognostic factors and risks to the survival of clinical cancer patients. More importantly, based on several available databases, we explore relationships between glycolytic enzymes and genetic changes or drug responses in urothelial cancer cells. Current advances in glycolysis-based inhibitors and their combinations are also discussed. Combining all of the evidence, we indicate their potential value for further research in basic science and clinical applications.

A glycolysis-based 4-mRNA signature correlates with the prognosis and cell cycle process in patients with bladder cancer

Background

Bladder cancer is one of the most prevalent malignancies worldwide. However, traditional indicators have limited predictive effects on the clinical outcomes of bladder cancer. The aim of this study was to develop and validate a glycolysis-related gene signature for predicting the prognosis of patients with bladder cancer that have limited therapeutic options.

Methods

mRNA expression profiling was obtained from patients with bladder cancer from The Cancer Genome Atlas (TCGA) database. Gene set enrichment analysis (GSEA) was conducted to identify glycolytic gene sets that were significantly different between bladder cancer tissues and paired normal tissues. A prognosis-related gene signature was constructed by univariate and multivariate Cox analysis. Kaplan–Meier curves and time-dependent receiver operating characteristic (ROC) curves were utilized to evaluate the signature. A nomogram combined with the gene signature and clinical parameters was constructed. Correlations between glycolysis-related gene signature and molecular characterization as well as cancer subtypes were analyzed. RT-qPCR was applied to analyze gene expression. Functional experiments were performed to determine the role of PKM2 in the proliferation of bladder cancer cells.

Results

Using a Cox proportional regression model, we established that a 4-mRNA signature (NUP205, NUPL2, PFKFB1 and PKM) was significantly associated with prognosis in bladder cancer patients. Based on the signature, patients were split into high and low risk groups, with different prognostic outcomes. The gene signature was an independent prognostic indicator for overall survival. The ability of the 4-mRNA signature to make an accurate prognosis was tested in two other validation datasets. GSEA was performed to explore the 4-mRNA related canonical pathways and biological processes, such as the cell cycle, hypoxia, p53 pathway, and PI3K/AKT/mTOR pathway. A heatmap showing the correlation between risk score and cell cycle signature was generated. RT-qPCR revealed the genes that were differentially expressed between normal and cancer tissues. Experiments showed that PKM2 plays essential roles in cell proliferation and the cell cycle.

Conclusion

The established 4‑mRNA signature may act as a promising model for generating accurate prognoses for patients with bladder cancer, but the specific biological mechanism needs further verification.

The metabolic landscape of urological cancers: New therapeutic perspectives

Deregulation of cell metabolism is an established cancer hallmark that contributes to tumor initiation and progression, as well as tumor heterogeneity. In solid tumors, alterations in different metabolic pathways, including glycolysis, pentose phosphate pathway, glutaminolysis and fatty acid metabolism, support the high proliferative rates and macromolecule biosynthesis of cancer cells. Despite advances in therapy, urothelial tumors still exhibit high recurrence and mortality rates, especially in advanced stages of disease. These tumors harbor gene mutations and expression patterns which play an important role in metabolic reprogramming. Taking into account the unique metabolic features underlying carcinogenesis in these cancers, new and promising therapeutic targets based on metabolic alterations must be considered. Furthermore, the combination of metabolic inhibitors with conventional targeted therapies may improve effectiveness of treatments. This review will summarize the metabolic alterations present in urological tumors and the results with metabolic inhibitors currently available.

The molecular mechanisms of LncRNA-correlated PKM2 in cancer metabolism

Reprogrammed metabolism is an important hallmark of cancer cells. Pyruvate kinase (PK) is one of the major rate-limiting enzymes in glucose metabolism. The M2 isoform of PK (PKM2), is considered to be an important marker of metabolic reprogramming and one of the key enzymes. Recently, through the continuous development of genome-wide analysis and functional studies, accumulating evidence has demonstrated that long non-coding RNAs (LncRNAs) play vital regulatory roles in cancer progression by acting as either potential oncogenes or tumor suppressors. Furthermore, several studies have shown that up-regulation of PKM2 in cancer tissues is associated with LncRNAs expression and patient survival. Thus, scientists have begun to unveil the mechanism of LncRNA-associated PKM2 in cancer metabolic progression. Based on these novel findings, in this mini-review, we summarize the detailed molecular mechanisms of LncRNA related to PKM2 in cancer metabolism. We expect that this work will promote a better understanding of the molecular mechanisms of PKM2, and provide a profound potential for targeting PKM2 to treat tumors.

Dimethylaminomicheliolide (DMAMCL) Suppresses the Proliferation of Glioblastoma Cells via Targeting Pyruvate Kinase 2 (PKM2) and Rewiring Aerobic Glycolysis

Glioblastoma (GBM) is the most prevalent malignant tumor in the central nervous system. Aerobic glycolysis, featured with elevated glucose consumption and lactate production, confers selective advantages on GBM by utilizing nutrients to support rapid cell proliferation and tumor growth. Pyruvate kinase 2 (PKM2), the last rate-limiting enzyme of glycolysis, is known to regulate aerobic glycolysis, and considered as a novel cancer therapeutic target. Herein, we aim to describe the cellular functions and mechanisms of a small molecular compound dimethylaminomicheliolide (DMAMCL), which has been used in clinical trials for recurrent GBM in Australia. Our results demonstrate that DMAMCL is effective on the inhibition of GBM cell proliferation and colony formation. MCL, the active metabolic form of DMAMCL, selectively binding to monomeric PKM2 and promoting its tetramerization, was also found to improve the pyruvate kinase activity of PKM2 in GBM cells. In addition, non-targeting metabolomics analysis reveals multiple metabolites involved in glycolysis, including lactate and glucose-6-phosphate, are decreased with DMAMCL treatment. The inhibitory effects of DMAMCL are observed to decrease in GBM cells upon PKM2 depletion, further confirming the importance of PKM2 in DMAMCL sensitivity. In conclusion, the activation of PKM2 by DMAMCL results in the rewiring aerobic glycolysis, which consequently suppresses the proliferation of GBM cells. Hence, DMAMCL represents a potential PKM2-targeted therapeutic agent against GBM.

Tumor M2-PK: A novel urine marker of bladder cancer

PURPOSE

Bladder cancer is a "Warburg-like" tumor characterized by a reliance on aerobic glycolysis and expression of pyruvate kinase M2 (PKM2). PKM2 oscillates between an active tetramer and an inactive dimer. We aim to further characterize PKM2, in particular PKM2 dimer, as a urinary biomarker of bladder cancer and a potential target for treatment.

METHODS

HTB-9, HTB-5, and UM-UC3 bladder cancer cells were assessed for proliferation under differential glucose levels using the hexosaminidase assay. Western blot and Blue-native analysis was performed for protein expression of PKM2. Shikonin, an herb that is known to bind and inhibit PKM2, was utilized to determine if PKM2 has a role in glucose usage and cellular proliferation in bladder cancer cells by caspase activity assay. Institutional review board approval was obtained to collect healthy control and bladder cancer patient urine samples. The ScheBo M2-PK EDTA Plasma Test was performed on urine samples to assess urine Tumor M2-PK values.

RESULTS

The three bladder cancer cell lines tested all demonstrate statistically significant increases in proliferation when exposed to higher level of glucose (200mg/dL). Similarly, low doses of glucose (25mg/dL) result in reduced proliferation. Increased cell growth in higher glucose concentration correlated with up-regulation of PKM2 protein expression. Shikonin, a PKM2 inhibitor, reduced cell proliferation and switched PKM2 isoforms from the dimer to tetramer. Lastly, dimer PKM2 (Tumor-M2PK) levels were assessed in the urine samples from bladder cancer (Bca) patients and healthy controls. Tumor M2-PK significantly correlated with the presence of BCa in our subjects.

CONCLUSIONS

Our studies demonstrate the potential of PKM2, specifically the dimer (Tumor-M2PK) as a target of drug therapy and as a urinary marker for bladder cancer.

PKM2, function and expression and regulation

Pyruvate kinase (PK), as one of the key enzymes for glycolysis, can encode four different subtypes from two groups of genes, although the M2 subtype PKM2 is expressed mainly during embryonic development in normal humans, and is closely related to tissue repair and regeneration, with the deepening of research, the role of PKM2 in tumor tissue has received increasing attention. PKM2 can be aggregated into tetrameric and dimeric forms, PKM2 in the dimer state can enter the nuclear to regulate gene expression, the transformation between them can play an important role in tumor cell energy supply, epithelial-mesenchymal transition (EMT), invasion and metastasis and cell proliferation. We will use the switching effect of PKM2 in glucose metabolism as the entry point to expand and enrich the Warburg effect. In addition, PKM2 can also regulate each other with various proteins by phosphorylation, acetylation and other modifications, mediate the different intracellular localization of PKM2 and then exert specific biological functions. In this paper, we will illustrate each of these points.

Subcellular compartmentalization of PKM2 identifies anti-PKM2 therapy response in vitro and in vivo mouse model of human non-small-cell lung cancer

Pyruvate kinase M2 (PKM2) is an alternatively spliced variant, which mediates the conversion of glucose to lactate in cancer cells under normoxic conditions, known as the Warburg effect. Previously, we demonstrated that PKM2 is one of 97 genes that are overexpressed in non-small-cell lung cancer (NSCLC) cell lines. Herein, we demonstrate a novel role of subcellular PKM2 expression as a biomarker of therapeutic response after targeting this gene by shRNA or small molecule inhibitor (SMI) of PKM2 enzyme activity in vitro and in vivo. We examined two established lung cancer cell lines, nine patients derived NSCLC and three normal lung fibroblast cell lines for PKM2 mRNA, protein and enzyme activity by RT-qPCR, immunocytochemistry (ICC), and Western blot analysis. All eleven NSCLC cell lines showed upregulated PKM2 enzymatic activity and protein expression mainly in their cytoplasm. Targeting PKM2 by shRNA or SMI, NSCLC cells showed significantly reduced mRNA, enzyme activity, cell viability, and colony formation, which also downregulated cytosolic PKM2 and upregulated nuclear enzyme activities. Normal lung fibroblast cell lines did not express PKM2, which served as negative controls. PKM2 targeting by SMI slowed tumor growth while gene-silencing significantly reduced growth of human NSCLC xenografts. Tumor sections from responding mice showed >70% reduction in cytoplasmic PKM2 with low or undetectable nuclear staining by immunohistochemistry (IHC). In sharp contrast, non-responding tumors showed a >38% increase in PKM2 nuclear staining with low or undetectable cytoplasmic staining. In conclusion, these results confirmed PKM2 as a target for cancer therapy and an unique function of subcellular PKM2, which may characterize therapeutic response to anti-PKM2 therapy in NSCLC.

Down-regulation of PKM2 decreases FASN expression in bladder cancer cells through AKT/mTOR/SREBP-1c axis

Fatty acid synthase (FASN) catalyzing the terminal steps in the de novo biogenesis of fatty acids is correlated with low survival and high disease recurrence in patients with bladder cancer. Pyruvate kinase M2 (PKM2) regulates the final step of glycolysis levels and provides a growth advantage to tumors. However, it is unclear whether the change of PKM2 has an effect on FASN and what is the mechanisms underlying. Here we describe a novel function of PKM2 in control of lipid metabolism by mediating transcriptional activation of FASN, showing the reduced expression of sterol regulatory element binding protein 1c (SREBP-1c). We first discovered that PKM2 physically interacts with the SREBP-1c using biochemical approaches, and downregulation of PKM2 reduced the expression of SREBP-1c by inactivating the AKT/mTOR signaling pathway, which in turn directly suppressed the transcription of major lipogenic genes FASN to reduce tumor growths. Furthermore, either PKM2 inhibitor-Shikonin or FASN inhibitor-TVB-3166 alone induced a strong antiproliferative and anticolony forming effect in bladder cancer cell line. The combination of both inhibitors exhibits a super synergistic effect on blocking the bladder cancer cells growth. It provides a new target and scientific basis for the treatment of bladder cancer.

Down-regulation of PKM2 enhances anticancer efficiency of THP on bladder cancer

Pyruvate kinase M2 (PKM2) regulates the final step of glycolysis levels that are correlated with the sensitivity of anticancer chemotherapeutic drugs. THP is one of the major drugs used in non‐muscle‐invasive bladder cancer instillation chemotherapy. However, low response ratio of THP (19.7%) treatment to human genitourinary tumours using collagen gel matrix has been observed. This study aims to investigate the effect of down‐regulation of PKM2 on THP efficiency. Via inhibitor or siRNA, the effects of reduced PKM2 on the efficiency of THP were determined in 2 human and 1 murine bladder cancer cell lines, using MTT, cologenic and fluorescence approaches. Molecular mechanisms of PKM2 on THP sensitization were explored by probing p‐AMPK and p‐STAT3 levels via WB. Syngeneic orthotopic bladder tumour model was applied to evaluate this efficiency in vivo, analysed by Kaplan‐Meier survival curves, body and bladder weights plus immunohistochemistric tumour biomarkers. PKM2 was overexpressed in bladder cancer cells and tissues, and down‐regulation of PKM2 enhanced the sensitivity of THP in vitro. Activation of AMPK is essential for THP to exert anti‐bladder cancer activities. On the other hand, down‐regulating PKM2 activates AMPK and inhibits STAT3, correlated with THP sensitivity. Compared with THP alone (400 μmol L⁻¹, 50 μL), the combination with metformin (60 mmol L⁻¹, 50 μL) stopped growth of bladder cancer completely in vivo (combination group VS normal group P = .078). Down‐regulating the expression of PKM2 enhances the anticancer efficiency of THP. This study provides a new insight for improving the chemotherapeutic effect of THP.

Proceedings of the 3rd Annual Albert Institute for Bladder Cancer Research Symposium

The Third Annual Albert Institute Bladder Symposium was held on September 8–10th, 2016, in Denver Colorado. Participants discussed several critical topics in the field of bladder cancer: 1) Best practices for tissue analysis and use to optimize correlative studies, 2) Modeling bladder cancer to facilitate understanding and innovation, 3) Targeted therapies for bladder cancer, 4) Tumor phylogeny in bladder cancer, 5) New Innovations in bladder cancer diagnostics. Our understanding of and approach to treating urothelial carcinoma is undergoing rapid advancement. Preclinical models of bladder cancer have been leveraged to increase our basic and mechanistic understanding of the disease. With the approval of immune checkpoint inhibitors for the treatment of advanced urothelial carcinoma, the treatment approach for these patients has quickly changed. In this light, molecularly-defined subtypes of bladder cancer and appropriate pre-clinical models are now essential to the further advancement and appropriate application of these therapeutic improvements. The optimal collection and processing of clinical urothelial carcinoma tissues samples will also be critical in the development of predictive biomarkers for therapeutic selection. Technological advances in other areas including optimal imaging technologies and micro/nanotechnologies are being applied to bladder cancer, especially in the localized setting, and hold the potential for translational impact in the treatment of bladder cancer patients. Taken together, advances in several basic science and clinical areas are now converging in bladder cancer. These developments hold the promise of shaping and improving the clinical care of those with the disease.

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.

Inhibition of Pyruvate Kinase M2 Markedly Reduces Chemoresistance of Advanced Bladder Cancer to Cisplatin

Chemoresistance to cisplatin is a principal cause of treatment failure and mortality of advanced bladder cancer (BC). The underlying mechanisms remain unclear, which hinders the development of preventive strategies. Recent data indicate that pyruvate kinase M2 (PKM2), a glycolytic enzyme for Warburg effect, is strongly upregulated in BC. This study explores the role of PKM2 in chemoresistance and whether inhibiting PKM2 augments the chemosensitivity to cisplatin and reduces BC growth and progression. We found that Shikonin binds PKM2 and inhibits BC cell survival in a dose-dependent but pyruvate kinase activity-independent manner. Down-regulation of PKM2 by shRNA blunts cellular responses to shikonin but enhances the responses to cisplatin. Shikonin and cisplatin together exhibit significantly greater inhibition of proliferation and apoptosis than when used alone. Induced cisplatin-resistance is strongly associated with PKM2 overexpression, and cisplatin-resistant cells respond sensitively to shikonin. In syngeneic mice, shikonin and cisplatin together, but not as single-agents, markedly reduces BC growth and metastasis. Based on these data, we conclude that PKM2 overexpression is a key mechanism of chemoresistance of advanced BC to cisplatin. Inhibition of PKM2 via RNAi or chemical inhibitors may be a highly effective approach to overcome chemoresistance and improve the outcome of advanced BC.