Tumor pyruvate kinase M2: A promising molecular target of gastrointestinal cancer

Targeted lactate dehydrogenase genes silencing in probiotic lactic acid bacteria: A possible paradigm shift in colorectal cancer treatment?

Even though the pathophysiology of colorectal cancer (CRC) is complicated and poorly understood, interactions between risk factors appear to be key in the development and progression of the malignancy. The popularity of using lactic acid bacteria (LAB) prebiotics and probiotics to modulate the tumor microenvironment (TME) has grown widely over the past decade. The objective of this study was therefore to determine the detrimental effects of LAB-derived lactic acid in the colonic mucosa in colorectal cancer management. Six library databases and a web search engine were used to execute a structured systematic search of the existing literature, considering all publications published up until August 2022. A total of 7817 papers were screened, all of which were published between 1995 and August 2022. However, only 118 articles met the inclusion criterion. Lactic acid has been directly linked to the massive proliferation of cancerous cells since the glycolytic pathway provides cancerous cells with not only ATP, but also biosynthetic intermediates for rapid growth and proliferation. Our research suggests that targeting LAB metabolic pathways is capable of suppressing tumor growth and that the LDH gene is critical for tumorigenesis. Silencing of Lactate dehydrogenase, A (LDHA), B (LDHB), (LDHL), and hicD genes should be explored to inhibit fermentative glycolysis yielding lactic acid as the by-product. More studies are necessary for a solid understanding of this topic so that LAB and their corresponding lactic acid by-products do not have more adverse effects than their widely touted positive outcomes in CRC management.

Targeting pyruvate kinase muscle isoform 2 (PKM2) in cancer: What do we know so far?

Cancer is a leading cause of death globally. Cancer cell transformation is the result of intricate crosstalk between intracellular components and proteins. A characteristic feature of cancer cells is the ability to reprogram their metabolic pathways to ensure their infinite proliferative potential. Pyruvate kinase muscle isoform 2 (PKM2) is a glycolytic enzyme that plays crucial roles in cancer, apart from carrying out its metabolic roles. PKM2 is involved in all the major events associated with cancer growth. Modulation of PKM2 activity (dimer inhibition or tetramer activation) has been successful in controlling cancer. However, recent studies provide contrary evidences regarding the oncogenic functions of PKM2. Moreover, several studies have highlighted the cancerous roles of PKM1 isoform in certain contexts. The present review aims at providing the current updates regarding PKM2 targeting in cancer. Further, the review discusses the contradictory results that suggest that both the isoforms of PKM can lead to cancer growth. In conclusion, the review emphasizes revisiting the approaches to target cancer metabolism through PKM to find novel and effective targets for anticancer therapy.

Discovery of boronic acid-based potent activators of tumor pyruvate kinase M2 and development of gastroretentive nanoformulation for oral dosing

Several studies have established that cancer cells explicitly over-express the less active isoform of pyruvate kinase M2 (PKM2) is critical for tumorigenesis. The activation of PKM2 towards tetramer formation may increase affinity towards phosphoenolpyruvate (PEP) and avoidance of the Warburg effect. Herein, we describe the design, synthesis, and development of boronic acid-based molecules as activators of PKM2. The designed molecules were inspired by existing anticancer scaffolds and several fragments were assembled in the derivatives. 6a-6d were synthesized using a multi-step synthetic strategy in 55-70% yields, starting from cheap and readily available materials. The compounds were selectively cytotoxic to kill the cancerous cells at 80 nM, while they were non-toxic to the normal cells. The kinetic studies established the compounds as novel activators of PKM2 and (E/Z)-(4-(3-(2-((4-chlorophenyl)amino)-4-(dimethylamino)thiazol-5-yl)-2-(ethoxycarbonyl)-3-oxoprop-1-en-1-yl) phenyl)boronic acid (6c) emerged as the most potent derivative. 6c was further evaluated using various in silico tools to understand the molecular mechanism of tetramer formation. Docking studies revealed that 6c binds to the PKM2 dimer at the dimeric interface. Further to ascertain the binding site and mechanism of action, rigorous MD (molecular dynamics) simulations were undertaken, which led to the conclusion that 6c stabilizes the center of the dimeric interface that possibly promotes tetramer formation. We further planned to make a tablet of the developed molecule for oral delivery, but it was seriously impeded owing to poor aqueous solubility of 6c. To improve aqueous solubility and retain 6c at the lower gastrointestinal tract, thiolated chitosan-based nanoparticles (TCNPs) were prepared and further developed as tablet dosage form to retain anticancer potency in the excised goat colon. Our findings may provide a valuable pharmacological mechanism for understanding metabolic underpinnings that may aid in the clinical development of new anticancer agents targeting PKM2.

Mangifera indica Extracts as Novel PKM2 Inhibitors for Treatment of Triple Negative Breast Cancer

Pyruvate kinase (PK), a key enzyme that determines glycolytic activity, has been known to support the metabolic phenotype of tumor cells, and specific pyruvate kinase isoform M2 (PKM2) has been reported to fulfill divergent biosynthetic and energetic requirements of cancerous cells. PKM2 is overexpressed in several cancer types and is an emerging drug target for cancer during recent years. Therefore, this study was carried out to identify PKM2 inhibitors from natural products for cancer treatment. Based on the objectives of this study, firstly, plant extract library was established. In order to purify protein for the establishment of enzymatic assay system, pET-28a-HmPKM2 plasmid was transformed to E. coli BL21 (DE3) cells for protein expression and purification. After the validation of enzymatic assay system, plant extract library was screened for the identification of inhibitors of PKM2 protein. Out of 51 plant extracts screened, four extracts Mangifera indica (leaf, seed, and bark) and Bombex ceiba bark extracts were found to be inhibitors of PKM2. In the current study, M. indica (leaf, seed, and bark) extracts were further evaluated dose dependently against PKM2. These extracts showed different degrees of concentration-dependent inhibition against PKM2 at 90-360 μg/ml concentrations. We have also investigated the anticancer potential of these extracts against MDA-MB231 cells and generated dose-response curves for the evaluation of IC50 values. M. indica (bark and seed) extracts significantly halted the growth of MDA-MB231 cells with IC50 values of 108 μg/ml and 33 μg/ml, respectively. Literature-based phytochemical analysis of M. indica was carried out, and M. indica-derived 94 compounds were docked against three binding sites of PKM2 for the identification of PKM2 inhibitors. The results of in silico based screening have unveiled various PKM2 modulators; however, further studies are recommended to validate their PKM2 inhibitory potential via in vitro biochemical assay. The results of this study provide novel findings for possible mechanism of action of M. indica (bark and seed) extracts against TNBC via PKM2 inhibition suggesting that M. indica might be of therapeutic interest for the treatment of TNBC.

A Novel Glycolysis-Related Four-mRNA Signature for Predicting the Survival of Patients With Breast Cancer

Background: Glycolysis is critical in the occurrence and development of tumors. Owing to the biological and clinical heterogeneity of patients with BRCA, the traditional predictive classification system is far from satisfactory. Survival and prognosis biomarkers related to glycolysis have broad application prospects for assessing the risk of patients and guiding their individualized treatment.

Methods: The mRNA expression profiles and clinical information of patients with BRCA were obtained from TCGA database, and glycolysis-related genes were obtained by GSEA. Patients with BRCA were randomly divided into the training cohort and testing cohort. Univariate and multivariate Cox analyses were used to establish and validate a new mRNA signature for predicting the prognosis of patients with BRCA.

Results: We established a four-gene breast cancer prediction signature that included PGK1, SDHC, PFKL, and NUP43. The patients with BRCA in the training cohort and testing cohort were divided into high-risk and low-risk groups based on the signature. The AUC values were 0.74 (training cohort), 0.806 (testing cohort) and 0.769 (entire cohort), thereby showing that the prediction performance of the signature is acceptable. Additionally, Cox regression analysis revealed that four-gene signature could independently predict the prognosis of BRCA patients without being affected by clinical factors.

Conclusion: We constructed a four-gene signature to predict the prognosis of patients with BRCA. This signature will aid in the early diagnosis and personalized treatment of breast cancer, but the specific associated biological mechanism requires further study.

Protein kinase function of pyruvate kinase M2 and cancer

Pyruvate kinase is a terminal enzyme in the glycolytic pathway, where it catalyzes the conversion of phosphoenolpyruvate to pyruvate and production of ATP via substrate level phosphorylation. PKM2 is one of four isoforms of pyruvate kinase and is widely expressed in many types of tumors and associated with tumorigenesis. In addition to pyruvate kinase activity involving the metabolic pathway, increasing evidence demonstrates that PKM2 exerts a non-metabolic function in cancers. PKM2 has been shown to be translocated into nucleus, where it serves as a protein kinase to phosphorylate various protein targets and contribute to multiple physiopathological processes. We discuss the nuclear localization of PKM2, its protein kinase function and association with cancers, and regulation of PKM2 activity.

Prognostic implications of epidermal growth factor receptor variant III expression and nuclear translocation in Chinese human gliomas

Objective

To determine the prognostic implications and clinical significance of epidermal growth factor receptor variant III (EGFRvIII) expression and EGFRvIII nuclear translocation in Chinese human gliomas.

Methods

We retrospectively examined EGFRvIII expression and EGFRvIII nuclear translocation using immunohistochemistry in specimens of 240 Chinese patients with glioma, including 84 World Health Organization (WHO) II gliomas, 84 WHO III gliomas and 72 glioblastomas (WHO IV). Factors that correlated with EGFRvIII and EGFRvIII nuclear translocation expression were analyzed by the Chi-square test. Kaplan-Meier methodology and Cox regression were used for the survival analysis.

Results

Log-rank tests showed that patient age, Karnofsky performance scale (KPS) score, tumor grade, EGFRvIII expression, EGFRvIII nuclear translocation, 1p/19q codeletion, isocitrate dehydrogenase (IDH) mutation, Ki-67 labeling index and O6-methylguanine-DNA methyltransferase (MGMT) status (P<0.05) were significantly correlated with overall survival (OS) time. Multivariate Cox regression analysis revealed that patient age, tumor grade, EGFRvIII nuclear translocation, 1p/19q codeletion, and IDH mutation (P<0.05) were significantly correlated with OS. Patients with a high level of EGFRvIII nuclear translocation (≥7%) had both significantly shorter OS [hazard ratio (HR): 1.920, 95% confidence interval (95% CI): 1.228−3.003, P=0.004] and progression-free survival (PFS) times (HR: 1.661, 95% CI: 1.116−2.471, P=0.012) than those with a low level of EGFRvIII nuclear translocation (<7%).

Conclusions

A high level of EGFRvIII nuclear translocation in glioma is an independent factor indicating a poor prognosis, but EGFRvIII expression is not an independent clinical prognostic factor. The level of EGFRvIII nuclear translocation maybe a novel and crucial prognostic biomarker in glioma.