Epigallocatechin gallate inhibits human tongue carcinoma cells via HK2‑mediated glycolysis

Targeting the Warburg effect: A revisited perspective from molecular mechanisms to traditional and innovative therapeutic strategies in cancer

Cancer reprogramming is an important facilitator of cancer development and survival, with tumor cells exhibiting a preference for aerobic glycolysis beyond oxidative phosphorylation, even under sufficient oxygen supply condition. This metabolic alteration, known as the Warburg effect, serves as a significant indicator of malignant tumor transformation. The Warburg effect primarily impacts cancer occurrence by influencing the aerobic glycolysis pathway in cancer cells. Key enzymes involved in this process include glucose transporters (GLUTs), HKs, PFKs, LDHs, and PKM2. Moreover, the expression of transcriptional regulatory factors and proteins, such as FOXM1, p53, NF-κB, HIF1α, and c-Myc, can also influence cancer progression. Furthermore, lncRNAs, miRNAs, and circular RNAs play a vital role in directly regulating the Warburg effect. Additionally, gene mutations, tumor microenvironment remodeling, and immune system interactions are closely associated with the Warburg effect. Notably, the development of drugs targeting the Warburg effect has exhibited promising potential in tumor treatment. This comprehensive review presents novel directions and approaches for the early diagnosis and treatment of cancer patients by conducting in-depth research and summarizing the bright prospects of targeting the Warburg effect in cancer.

The roles of epigallocatechin gallate in the tumor microenvironment, metabolic reprogramming, and immunotherapy

Cancer, a disease that modern medicine has not fully understood and conquered, with its high incidence and mortality, deprives countless patients of health and even life. According to global cancer statistics, there were an estimated 19.3 million new cancer cases and nearly 10 million cancer deaths in 2020, with the age-standardized incidence and mortality rates of 201.0 and 100.7 per 100,000, respectively. Although remarkable advancements have been made in therapeutic strategies recently, the overall prognosis of cancer patients remains not optimistic. Consequently, there are still many severe challenges to be faced and difficult problems to be solved in cancer therapy today. Epigallocatechin gallate (EGCG), a natural polyphenol extracted from tea leaves, has received much attention for its antitumor effects. Accumulating investigations have confirmed that EGCG can inhibit tumorigenesis and progression by triggering apoptosis, suppressing proliferation, invasion, and migration, altering tumor epigenetic modification, and overcoming chemotherapy resistance. Nevertheless, its regulatory roles and biomolecular mechanisms in the immune microenvironment, metabolic microenvironment, and immunotherapy remain obscure. In this article, we summarized the most recent updates about the effects of EGCG on tumor microenvironment (TME), metabolic reprogramming, and anti-cancer immunotherapy. The results demonstrated EGCG can promote the anti-cancer immune response of cytotoxic lymphocytes and dendritic cells (DCs), attenuate the immunosuppression of myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), and inhibit the tumor-promoting functions of tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), and various stromal cells including cancer-associated fibroblasts (CAFs), endothelial cells (ECs), stellate cells, and mesenchymal stem/stromal cells (MSCs). Additionally, EGCG can suppress multiple metabolic reprogramming pathways, including glucose uptake, aerobic glycolysis, glutamine metabolism, fatty acid anabolism, and nucleotide synthesis. Finally, EGCG, as an immunomodulator and immune checkpoint blockade, can enhance immunotherapeutic efficacy and may be a promising candidate for antitumor immunotherapy. In conclusion, EGCG plays versatile regulatory roles in TME and metabolic reprogramming, which provides novel insights and combined therapeutic strategies for cancer immunotherapy.

Chemopreventive and Biological Strategies in the Management of Oral Potentially Malignant and Malignant Disorders

Oral potentially malignant disorders (OPMD) and oral squamous cell carcinoma (OSCC) represent a significant global health burden due to their potential for malignant transformation and the challenges associated with their diagnosis and treatment. Chemoprevention, an innovative approach aimed at halting or reversing the neoplastic process before full malignancy, has emerged as a promising avenue for mitigating the impact of OPMD and OSCC. The pivotal role of chemopreventive strategies is underscored by the need for effective interventions that go beyond traditional therapies. In this regard, chemopreventive agents offer a unique opportunity to intercept disease progression by targeting the molecular pathways implicated in carcinogenesis. Natural compounds, such as curcumin, green tea polyphenols, and resveratrol, exhibit anti-inflammatory, antioxidant, and anti-cancer properties that could make them potential candidates for curtailing the transformation of OPMD to OSCC. Moreover, targeted therapies directed at specific molecular alterations hold promise in disrupting the signaling cascades driving OSCC growth. Immunomodulatory agents, like immune checkpoint inhibitors, are gaining attention for their potential to harness the body's immune response against early malignancies, thus impeding OSCC advancement. Additionally, nutritional interventions and topical formulations of chemopreventive agents offer localized strategies for preventing carcinogenesis in the oral cavity. The challenge lies in optimizing these strategies for efficacy, safety, and patient compliance. This review presents an up to date on the dynamic interplay between molecular insights, clinical interventions, and the broader goal of reducing the burden of oral malignancies. As research progresses, the synergy between early diagnosis, non-invasive biomarker identification, and chemopreventive therapy is poised to reshape the landscape of OPMD and OSCC management, offering a glimpse of a future where these diseases are no longer insurmountable challenges but rather preventable and manageable conditions.

Natural Product-Based Glycolysis Inhibitors as a Therapeutic Strategy for Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor-Resistant Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related deaths worldwide. Targeted therapy against the epidermal growth factor receptor (EGFR) is a promising treatment approach for NSCLC. However, resistance to EGFR tyrosine kinase inhibitors (TKIs) remains a major challenge in its clinical management. EGFR mutation elevates the expression of hypoxia-inducible factor-1 alpha to upregulate the production of glycolytic enzymes, increasing glycolysis and tumor resistance. The inhibition of glycolysis can be a potential strategy for overcoming EGFR-TKI resistance and enhancing the effectiveness of EGFR-TKIs. In this review, we specifically explored the effectiveness of pyruvate dehydrogenase kinase inhibitors and lactate dehydrogenase A inhibitors in combating EGFR-TKI resistance. The aim was to summarize the effects of these natural products in preclinical NSCLC models to provide a comprehensive understanding of the potential therapeutic effects. The study findings suggest that natural products can be promising inhibitors of glycolytic enzymes for the treatment of EGFR-TKI-resistant NSCLC. Further investigations through preclinical and clinical studies are required to validate the efficacy of natural product-based glycolytic inhibitors as innovative therapeutic modalities for NSCLC.

The Promoting Role of HK II in Tumor Development and the Research Progress of Its Inhibitors

Increased glycolysis is a key characteristic of malignant cells that contributes to their high proliferation rates and ability to develop drug resistance. The glycolysis rate-limiting enzyme hexokinase II (HK II) is overexpressed in most tumor cells and significantly affects tumor development. This paper examines the structure of HK II and the specific biological factors that influence its role in tumor development, as well as the potential of HK II inhibitors in antitumor therapy. Furthermore, we identify and discuss the inhibitors of HK II that have been reported in the literature.

MicroRNA-495: a therapeutic and diagnostic tumor marker

Therapeutic and diagnostic progresses have significantly reduced the mortality rate among cancer patients during the last decade. However, there is still a high rate of mortality among cancer patients. One of the important reasons involved in the high mortality rate is the late diagnosis in advanced tumor stages that causes the failure of therapeutic strategies in these patients. Therefore, investigating the molecular mechanisms involved in tumor progression has an important role in introducing the efficient early detection markers. MicroRNAs (miRNAs) as stable factors in body fluids are always considered as non-invasive diagnostic and prognostic markers. In the present review, we investigated the role of miR-495 in tumor progression. It has been reported that miR-495 has mainly a tumor suppressor function through the regulation of transcription factors and tyrosine kinases as well as cellular processes such as multidrug resistance, chromatin remodeling, and signaling pathways. This review can be an effective step towards introducing the miR-495 as a non-invasive diagnostic/prognostic marker as well as a suitable target in tumor therapy.

Phytochemicals Target Multiple Metabolic Pathways in Cancer

Cancer metabolic reprogramming is a complex process that provides malignant cells with selective advantages to grow and propagate in the hostile environment created by the immune surveillance of the human organism. This process underpins cancer proliferation, invasion, antioxidant defense, and resistance to anticancer immunity and therapeutics. Perhaps not surprisingly, metabolic rewiring is considered to be one of the "Hallmarks of cancer". Notably, this process often comprises various complementary and overlapping pathways. Today, it is well known that highly selective inhibition of only one of the pathways in a tumor cell often leads to a limited response and, subsequently, to the emergence of resistance. Therefore, to increase the overall effectiveness of antitumor drugs, it is advisable to use multitarget agents that can simultaneously suppress several key processes in the tumor cell. This review is focused on a group of plant-derived natural compounds that simultaneously target different pathways of cancer-associated metabolism, including aerobic glycolysis, respiration, glutaminolysis, one-carbon metabolism, de novo lipogenesis, and β-oxidation of fatty acids. We discuss only those compounds that display inhibitory activity against several metabolic pathways as well as a number of important signaling pathways in cancer. Information about their pharmacokinetics in animals and humans is also presented. Taken together, a number of known plant-derived compounds may target multiple metabolic and signaling pathways in various malignancies, something that bears great potential for the further improvement of antineoplastic therapy.

Mitochondria in oral cancer stem cells: Unraveling the potential drug targets for new and old drugs

Head and neck cancer is a major health problem worldwide, with most cases arising in the oral cavity. Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer, accounting for over 90% of all cases. Compared to other types of cancer, OSCC, has the worse prognosis, with a 5-year survival rate of 50%. Additionally, OSCC is characterized by a high rate of resistance to chemotherapy treatment, which may be partly explained by the presence of cancer stem cells (CSC) subpopulation. CSC can adapt to harmful environmental condition and are highly resistant to both chemotherapy and radiotherapy treatments, thus contributing to tumor relapse. The aim of this review is to highlight the role of mitochondria in oral CSC as a potential target for oral cancer treatment. For this purpose, we reviewed some fundamental aspects of the most validated protein markers of stemness, autophagy, the mitochondrial function and energy metabolism in oral CSC. Moreover, a discussion will be made on why energy metabolism, especially oxidative phosphorylation in CSC, may offer such a diverse source of original pharmacological target for new drugs. Finally, we will describe some drugs able to disturb mitochondrial function, with emphasis on those aimed to interrupt the electron transport chain function, as novel therapeutic strategies in multidrug-resistant oral CSC. The reutilization of old drugs approved for clinical use as new antineoplastics, in cancer treatment, is also matter of revision.

Epigallocatechin-3-Gallate Therapeutic Potential in Cancer: Mechanism of Action and Clinical Implications

Cellular signaling pathways involved in the maintenance of the equilibrium between cell proliferation and apoptosis have emerged as rational targets that can be exploited in the prevention and treatment of cancer. Epigallocatechin-3-gallate (EGCG) is the most abundant phenolic compound found in green tea. It has been shown to regulate multiple crucial cellular signaling pathways, including those mediated by EGFR, JAK-STAT, MAPKs, NF-κB, PI3K-AKT-mTOR, and others. Deregulation of the abovementioned pathways is involved in the pathophysiology of cancer. It has been demonstrated that EGCG may exert anti-proliferative, anti-inflammatory, and apoptosis-inducing effects or induce epigenetic changes. Furthermore, preclinical and clinical studies suggest that EGCG may be used in the treatment of numerous disorders, including cancer. This review aims to summarize the existing knowledge regarding the biological properties of EGCG, especially in the context of cancer treatment and prophylaxis.

Aiding Cancer's "Sweet Tooth": Role of Hexokinases in Metabolic Reprogramming

Hexokinases (HKs) convert hexose sugars to hexose-6-phosphate, thus trapping them inside cells to meet the synthetic and energetic demands. HKs participate in various standard and altered physiological processes, including cancer, primarily through the reprogramming of cellular metabolism. Four canonical HKs have been identified with different expression patterns across tissues. HKs 1-3 play a role in glucose utilization, whereas HK 4 (glucokinase, GCK) also acts as a glucose sensor. Recently, a novel fifth HK, hexokinase domain containing 1 (HKDC1), has been identified, which plays a role in whole-body glucose utilization and insulin sensitivity. Beyond the metabolic functions, HKDC1 is differentially expressed in many forms of human cancer. This review focuses on the role of HKs, particularly HKDC1, in metabolic reprogramming and cancer progression.

A new strategy for osteoarthritis therapy: Inhibition of glycolysis

Osteoarthritis (OA) is a common degenerative disease of the joints. It is primarily caused by age, obesity, mechanical damage, genetics, and other factors, leading to cartilage degradation, synovial inflammation, and subchondral sclerosis with osteophyte formation. Many recent studies have reported that glycolysis disorders are related lead to OA. There is a close relationship between glycolysis and OA. Because of their hypoxic environment, chondrocytes are highly dependent on glycolysis, their primary energy source for chondrocytes. Glycolysis plays a vital role in OA development. In this paper, we comprehensively summarized the abnormal expression of related glycolytic enzymes in OA, including Hexokinase 2 (HK2), Pyruvate kinase 2 (PKM2), Phosphofructokinase-2/fructose-2, 6-Bisphosphatase 3 (PFKFB3), lactate dehydrogenase A (LDHA), and discussed the potential application of glycolysis in treating OA. Finally, the natural products that can regulate the glycolytic pathway were summarized. Targeting glucose transporters and rate-limiting enzymes to glycolysis may play an essential role in treating OA.

Targeting Glucose Metabolism Enzymes in Cancer Treatment: Current and Emerging Strategies

Simple Summary

Reprogramming of glucose metabolism is a hallmark of cancer and can be targeted by therapeutic agents. Some metabolism regulators, such as ivosidenib and enasidenib, have been approved for cancer treatment. Currently, more advanced and effective glucose metabolism enzyme-targeted anticancer drugs have been developed. Furthermore, some natural products have shown efficacy in killing tumor cells by regulating glucose metabolism, offering novel therapeutic opportunities in cancer. However, most of them have failed to be translated into clinical applications due to low selectivity, high toxicity, and side effects. Recent studies suggest that combining glucose metabolism modulators with chemotherapeutic drugs, immunotherapeutic drugs, and other conventional anticancer drugs may be a future direction for cancer treatment.

Abstract

Reprogramming of glucose metabolism provides sufficient energy and raw materials for the proliferation, metastasis, and immune escape of cancer cells, which is enabled by glucose metabolism-related enzymes that are abundantly expressed in a broad range of cancers. Therefore, targeting glucose metabolism enzymes has emerged as a promising strategy for anticancer drug development. Although several glucose metabolism modulators have been approved for cancer treatment in recent years, some limitations exist, such as a short half-life, poor solubility, and numerous adverse effects. With the rapid development of medicinal chemicals, more advanced and effective glucose metabolism enzyme-targeted anticancer drugs have been developed. Additionally, several studies have found that some natural products can suppress cancer progression by regulating glucose metabolism enzymes. In this review, we summarize the mechanisms underlying the reprogramming of glucose metabolism and present enzymes that could serve as therapeutic targets. In addition, we systematically review the existing drugs targeting glucose metabolism enzymes, including small-molecule modulators and natural products. Finally, the opportunities and challenges for glucose metabolism enzyme-targeted anticancer drugs are also discussed. In conclusion, combining glucose metabolism modulators with conventional anticancer drugs may be a promising cancer treatment strategy.

The influence of antioxidant dietary-derived polyphenolic combination on breast cancer: Molecular study

Breast cancer remains a leading cause of female mortality worldwide. Therefore, novel complementary treatments have been sought. Recently, there has been a growing interest in investigating the possible complementary effects of polyphenolic compounds against various malignancies. In the present study, using MCF-7 and MDA-MB-231 human breast adenocarcinoma cells, the anticancer efficacy of a polyphenolic mixture (PFM) was investigated. PFM is composed of curcumin, resveratrol, epigallocatechin gallate, and quercetin. PFM treatment led to a dose-dependent inhibition of cell proliferation, with IC₅₀ values of 25.9 ± 3 µg/ml and 29.4 ± 0.9 µg/ml for MCF-7 and MDA-MB-231 cells, respectively. In addition, PFM induced apoptosis in MDA-MB-231 cells and cell cycle arrest at the S phase in MCF-7 cells. Using RT-qPCR, PFM treatment was observed to result in significant downregulation of the oncogenic miR-155 (P < 0.05), as well as significant downregulation of the rate-limiting glycolytic enzyme, hexokinase 2 (HK2) (P < 0.05), while upregulating the expression of the zinc finger E-box binding homeobox 2 gene (P < 0.01). PFM was also found to exert an anti-migration effect in breast cancer cells using the wound healing assay, as well as significantly (P < 0.05) increasing the median survival of Ehrlich ascites carcinoma (EAC) tumor-bearing mice. These results suggest that PFM possesses potential antitumor effects against breast cancer. A possible mechanism of action could be due to PFM's effect in modulating the expression of the glycolytic enzyme HK2 through suppression of miR-155 in MCF-7 cells. Combining polyphenolic compounds that interact with one another could result in synergistic effects that potentially target various tumour hallmarks.

Medicinal Chemistry Targeting Mitochondria: From New Vehicles and Pharmacophore Groups to Old Drugs with Mitochondrial Activity

Interest in tumor cell mitochondria as a pharmacological target has been rekindled in recent years. This attention is due in part to new publications documenting heterogenous characteristics of solid tumors, including anoxic and hypoxic zones that foster cellular populations with differentiating metabolic characteristics. These populations include tumor-initiating or cancer stem cells, which have a strong capacity to adapt to reduced oxygen availability, switching rapidly between glycolysis and oxidative phosphorylation as sources of energy and metabolites. Additionally, this cell subpopulation shows high chemo- and radioresistance and a high capacity for tumor repopulation. Interestingly, it has been shown that inhibiting mitochondrial function in tumor cells affects glycolysis pathways, cell bioenergy, and cell viability. Therefore, mitochondrial inhibition may be a viable strategy for eradicating cancer stem cells. In this context, medicinal chemistry research over the last decade has synthesized and characterized "vehicles" capable of transporting novel or existing pharmacophores to mitochondrial tumor cells, based on mechanisms that exploit the physicochemical properties of the vehicles and the inherent properties of the mitochondria. The pharmacophores, some of which have been isolated from plants and others, which were synthesized in the lab, are diverse in chemical nature. Some of these molecules are active, while others are prodrugs that have been evaluated alone or linked to mitochondria-targeted agents. Finally, researchers have recently described drugs with well-proven safety and efficacy that may exert a mitochondria-specific inhibitory effect in tumor cells through noncanonical mechanisms. The effectiveness of these molecules may be improved by linking them to mitochondrial carrier molecules. These promising pharmacological agents should be evaluated alone and in combination with classic chemotherapeutic drugs in clinical studies.

Sinomenine Inhibits Non-Small Cell Lung Cancer via Downregulation of Hexokinases II-Mediated Aerobic Glycolysis

Background

Addiction to aerobic glycolysis is a common metabolic phenotype in human non-small cell lung cancer (NSCLC). The natural product Sinomenine (Sin) exhibits significant anti-tumor effects in various human cancers. However, the underlying mechanism remains elusive.

Methods

The inhibitory effect of Sin on NSCLC cells was determined by MTS and soft agar assays. The glycolysis efficacy of NSCLC cells was examined by glucose uptake and lactate production. The activation of Akt signaling and the protein level of hexokinases II (HK2) were examined by immunoblot (IB), qRT-PCR, and immunohistochemical staining (IHC). The in vivo anti-tumor effect of Sin was validated by the xenograft mouse model.

Results

We showed that HK2 is highly expressed in NSCLC tissues and cell lines. Depletion of HK2 suppressed cell viability, anchorage-independent colony formation, and xenograft tumor growth. Sinomenine exhibited a profound inhibitory effect on NSCLC cells by reducing HK2-mediated glycolysis both in vitro and in vivo. Ectopic overexpression of HK2 compromised these anti-tumor efficacies in sinomenine-treated NSCLC cells. Moreover, we revealed that sinomenine decreased Akt activity, which caused the down-regulation of HK2-mediated glycolysis. Knockdown of Akt reduced HK2 protein level and impaired glycolysis. In contrast, overexpression of constitutively activated Akt1 reversed this phenotype.

Conclusion

This study suggests that targeting HK2-mediated aerobic glycolysis is required for sinomenine-mediated anti-tumor activity.

Regulatory Role of Hexokinase 2 in Modulating Head and Neck Tumorigenesis

To support great demand of cell growth, cancer cells preferentially obtain energy and biomacromolecules by glycolysis over mitochondrial oxidative phosphorylation (OxPhos). Among all glycolytic enzymes, hexokinase (HK), a rate-limiting enzyme at the first step of glycolysis to catalyze cellular glucose into glucose-6-phosphate, is herein emphasized. Four HK isoforms, HK1-HK4, were discovered in nature. It was shown that HK2 expression is enriched in many tumor cells and correlated with poorer survival rates in most neoplastic cells. HK2-mediated regulations for cell malignancy and mechanistic cues in regulating head and neck tumorigenesis, however, are not fully elucidated. Cellular malignancy index, such as cell growth, cellular motility, and treatment sensitivity, and molecular alterations were determined in HK2-deficient head and neck squamous cell carcinoma (HNSCC) cells. By using various cancer databases, HK2, but not HK1, positively correlates with HNSCC progression in a stage-dependent manner. A high HK2 expression was detected in head and neck cancerous tissues compared with their normal counterparts, both in mouse and human subjects. Loss of HK2 in HNSCC cells resulted in reduced cell (in vitro) and tumor (in vivo) growth, as well as decreased epithelial-mesenchymal transition–mediated cell movement; in contrast, HK2-deficient HNSCC cells exhibited greater sensitivity to chemotherapeutic drugs cisplatin and 5-fluorouracil but are more resistant to photodynamic therapy, indicating that HK2 expression could selectively define treatment sensitivity in HNSCC cells. At the molecular level, it was found that HK2 alteration drove metabolic reprogramming toward OxPhos and modulated oncogenic Akt and mutant TP53-mediated signals in HNSCC cells. In summary, the present study showed that HK2 suppression could lessen HNSCC oncogenicity and modulate therapeutic sensitivity, thereby being an ideal therapeutic target for HNSCCs.

Progress in Drug and Formulation Development for the Chemoprevention of Oral Squamous Cell Carcinoma: A Review

BACKGROUND

Cancer is a life-threatening global problem with high incidence rates. Prioritizing the prevention of cancer, chemopreventive agents have drawn much attention from the researchers.

OBJECTIVE

This review focuses on the discussion of the progress in the development of chemopreventive agents and formulations related to the prevention of oral cancer.

METHODS

In this perspective, an extensive literature survey was carried out to understand the mechanism, control and chemoprevention of oral cancer. Different patented agents and formulations have also exhibited cancer preventive efficacy in experimental studies. This review summarizes the etiology of oral cancer and developments in prevention strategies.

RESULTS

The growth of oral cancer is a multistep activity necessitating the accumulation of genetic as well as epigenetic alterations in key regulatory genes. Many risk factors are associated with oral cancer. Genomic technique for sequencing all tumor specimens has been made available to help detect mutations. The recent development of molecular pathway and genetic tools has made the process of diagnosis easier, better forecast and efficient therapeutic management. Different chemical agents have been studied for their efficacy to prevent oral cancer and some of them have shown promising results.

CONCLUSION

Use of chemopreventive agents, either synthetic or natural origin, to prevent carcinogenesis is a worthy concept in the management of cancers. Preventive measures are helpful in controlling the occurrence or severity of the disease. The demonstrated results of preventive agents have opened an arena for the development of promising chemopreventive agents in the management of oral squamous cell carcinoma.

Effects of flavonoids on tongue squamous cell carcinoma

Squamous cell carcinoma (SCC) of the tongue is associated with tobacco use, alcohol abuse, and human papillomavirus (HPV) infections. While clinical outcomes have recently improved for HPV-positive patients in general, 50% of patients suffering from tongue cancer die within 5 years of being diagnosed. Flavonoids are secondary plant metabolites with a wide range of biological activities including antioxidant, anti-inflammatory, and anticancer activities. Flavonoids have generated high interest as therapeutic agents owing to their low toxicity and their effects on a large variety of cancer cell types. In this literature review, we evaluate the actions of flavonoids on SCC of the tongue demonstrated in both in vivo and in vitro models.

Targeting Glycolysis with Epigallocatechin-3-Gallate Enhances the Efficacy of Chemotherapeutics in Pancreatic Cancer Cells and Xenografts

Pancreatic cancer is a complex disease, in need of new therapeutic approaches. In this study, we explored the effect and mechanism of action of epigallocatechin-3-gallate (EGCG), a major polyphenol in green tea, alone and in combination with current chemotherapeutics on pancreatic cancer cell growth, focusing on glycolysis metabolism. Moreover, we investigated whether EGCG's effect is dependent on its ability to induce reactive oxygen species (ROS). EGCG reduced pancreatic cancer cell growth in a concentration-dependent manner and the growth inhibition effect was further enhanced under glucose deprivation conditions. Mechanistically, EGCG induced ROS levels concentration-dependently. EGCG affected glycolysis by suppressing the extracellular acidification rate through the reduction of the activity and levels of the glycolytic enzymes phosphofructokinase and pyruvate kinase. Cotreatment with catalase abrogated EGCG's effect on phosphofructokinase and pyruvate kinase. Furthermore, EGCG sensitized gemcitabine to inhibit pancreatic cancer cell growth in vitro and in vivo. EGCG and gemcitabine, given alone, reduced pancreatic tumor xenograft growth by 40% and 52%, respectively, whereas the EGCG/gemcitabine combination reduced tumor growth by 67%. EGCG enhanced gemcitabine's effect on apoptosis, cell proliferation, cell cycle and further suppressed phosphofructokinase and pyruvate kinase levels. In conclusion, EGCG is a strong combination partner of gemcitabine reducing pancreatic cancer cell growth by suppressing glycolysis.

Suppressing glucose metabolism with epigallocatechin-3-gallate (EGCG) reduces breast cancer cell growth in preclinical models

Numerous studies propose that epigallocatechin-3-gallate (EGCG), an abundant polyphenol in green tea, has anti-cancer properties. However, its mechanism of action in breast cancer remains unclear. This study investigated the capacity of EGCG to suppress breast cancer cell growth in vitro and in vivo, characterizing the underlying mechanisms, focusing on the effect of EGCG on glucose metabolism. EGCG reduced breast cancer 4T1 cell growth in a concentration- (10-320 μM) and time- (12-48 h) dependent manner. EGCG induced breast cancer apoptotic cell death at 24 h, as evidenced by annexin V/PI, caspase 3, caspase 8 and caspase 9 activation. Furthermore, EGCG affected the expression of 16 apoptosis-related genes, and promoted mitochondrial depolarization. EGCG induced autophagy concentration-dependently in 4T1 cells by modulating the levels of the autophagy-related proteins Beclin1, ATG5 and LC3B. Moreover, EGCG affected glucose, lactate and ATP levels. Mechanistically, EGCG significantly inhibited the activities and mRNA levels of the glycolytic enzymes hexokinase (HK), phosphofructokinase (PFK), and lactic dehydrogenase (LDH), and to a lesser extent the activity of pyruvate kinase (PK). In addition, EGCG decreased the expression of hypoxia-inducible factor 1α (HIF1α) and glucose transporter 1 (GLUT1), critical players in regulating glycolysis. In vivo, EGCG reduced breast tumor weight in a dose-dependent manner, reduced glucose and lactic acid levels and reduced the expression of the vascular endothelial growth factor (VEGF). In conclusion, EGCG exerts an anti-tumor effect through the inhibition of key enzymes that participate in the glycolytic pathway and the suppression of glucose metabolism.

Targeting Tumor Metabolism with Plant-Derived Natural Products: Emerging Trends in Cancer Therapy

Recognition of neoplastic metabolic reprogramming as one of cancer's hallmarks has paved the way for developing novel metabolism-targeted therapeutic approaches. The use of plant-derived natural bioactive compounds for this endeavor is especially promising, due to their diverse structures and multiple targets. Hence, over the past decade, a growing number of studies have assessed the impact of phytochemicals on tumor cell metabolism, aiming at improving current knowledge on their mechanisms of action and, at the same time, evaluating their potential as anti-cancer metabolic modulators. In this Review, we focus on three classes of plant-derived compounds with promising anti-cancer activity-phenolic compounds, isoprenoids, and alkaloids-to describe their effects on major energetic and biosynthetic pathways of human tumor cells. Such a comprehensive and integrated account of the ability of these compounds to hit different metabolic targets is expected to contribute to the rational design and critical assessment of novel anti-cancer therapies based on natural-product-mediated metabolic reprogramming.

Salvianolic acid B inhibits glycolysis in oral squamous cell carcinoma via targeting PI3K/AKT/HIF-1α signaling pathway

Our previous study demonstrated a progressive glycolytic perturbation during the course of DMBA-induced hamster oral carcinogenesis, which was attenuated by salvianolic acid B (Sal-B) treatment along with decreased incidences of oral squamous cell carcinoma (OSCC) formation. It was proposed that metabolic modulation should be an additional mode of action attributable to Sal-B’s anti-carcinogenic activity. However, the molecular mechanisms underlying Sal-B-induced metabolic modulation function remained elusive. In the present study, we performed next-generation sequencing (NGS) profiling in the same animal model and found Sal-B treatment evoked a general downregulation of the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and hypoxia inducible factor 1α subunit (HIF-1α) signaling pathways, which might contribute to Sal-B’s metabolic modulation activity. The inhibitory effects of Sal-B on aerobic glycolysis, as well as PI3K/AKT and HIF-1α signaling pathways, were validated in two well-characterized OSCC cell lines (Cal27 and HN4), and premalignant oral Leuk1 cells and Sal-B treatment led to elevation of the loss of mitochondrial membrane potential (MMP), increased cell apoptosis, and reduced abilities of colony formation. Rescue assays suggested that compared with Sal-B treatment group, Akt or hif-1a overexpression attenuated the inhibitory effect of Sal-B on glucose uptake and intracellular lactate level. Taken together, our results suggested that Sal-B modulated aberrant glucose metabolism via the PI3K/AKT/HIF-1α signaling pathways, which might contribute to the anti-carcinogenic activity of Sal-B.

Deguelin inhibits non-small cell lung cancer via down-regulating Hexokinases II-mediated glycolysis

Hexokinases II (HK2) is a hub in the regulation of cancer cell glycolysis. Here we reported deguelin, a natural compound which has been studied in various tumor types, has a profound anti-tumor effect on human non-small cell lung cancer (NSCLC) via directly down-regulating of glycolysis. In NSCLC cell lines and primary NSCLC tissue, we found HK2 is overexpressed. Deguelin treatment markedly inhibited anchorage-dependent and independent growth of NSCLC cell lines. We revealed that deguelin exposure impaired glucose metabolism by inhibiting Akt-mediated Hexokinase II expression, overexpression of constitutively activated Akt1 substantially rescued deguelin-induced glycolysis suppression. Moreover, deguelin suppressed HK2 presence on mitochondrial outer membrane and induced apoptosis. The in vivo data indicated that deguelin prominently restrained tumor development in a xenograft mouse model. Thus, deguelin appears to be a promising new therapeutic agent for lung cancer and may be considered for further studies in other animal models and in clinical trials.

Effects of green tea on miRNA and microbiome of oral epithelium

Consumption of green tea (GT) extracts or purified catechins has shown the ability to prevent oral and other cancers and inhibit cancer progression in rodent models, but the evidence for this in humans is mixed. Working with humans, we sought to understand the source of variable responses to GT by examining its effects on oral epithelium. Lingual epithelial RNA and lingual and gingival microbiota were measured before and after 4 weeks of exposure in tobacco smokers, whom are at high risk of oral cancer. GT consumption had on average inconsistent effects on miRNA expression in the oral epithelium. Only analysis that examined paired miRNAs, showing changed and coordinated expression with GT exposure, provided evidence for a GT effect on miRNAs, identifying miRNAs co-expressed with two hubs, miR-181a-5p and 301a-3p. An examination of the microbiome on cancer prone lingual mucosa, in contrast, showed clear shifts in the relative abundance of Streptococcus and Staphylococcus, and other genera after GT exposure. These data support the idea that tea consumption can consistently change oral bacteria in humans, which may affect carcinogenesis, but argue that GT effects on oral epithelial miRNA expression in humans vary between individuals.

The critical role of epigallocatechin gallate in regulating mitochondrial metabolism

Epigallocatechin gallate (EGCG), one of polyphenols isolated from green tea, exhibits biology-benefiting effects with minimum severe adverse. EGCG is known to be a mitochondrion-targeting medicinal agent, regulating mitochondrial metabolism, including mitochondrial biogenesis, mitochondrial bioenergetics, and mitochondria-mediated cell cycle and apoptosis. EGCG might exhibit either antioxidative activity to prevent against oxidative stress or pro-oxidative activity to counteract cancer cells, which depends on the cellular stress situations, cell types and the concentration of EGCG. Recent research has gained positive and promising data. This review will discuss the interaction between EGCG and mitochondrion.

The critical role of epigallocatechin gallate in regulating mitochondrial metabolism

Epigallocatechin gallate (EGCG), one of polyphenols isolated from green tea, exhibits biology-benefiting effects with minimum severe adverse. EGCG is known to be a mitochondrion-targeting medicinal agent, regulating mitochondrial metabolism, including mitochondrial biogenesis, mitochondrial bioenergetics, and mitochondria-mediated cell cycle and apoptosis. EGCG might exhibit either antioxidative activity to prevent against oxidative stress or pro-oxidative activity to counteract cancer cells, which depends on the cellular stress situations, cell types and the concentration of EGCG. Recent research has gained positive and promising data. This review will discuss the interaction between EGCG and mitochondrion.

Expression of the bitter receptor T2R38 in pancreatic cancer: localization in lipid droplets and activation by a bacteria-derived quorum-sensing molecule

T2R38 belongs to the family of bitter receptors and was initially detected in cells of the oral cavity. We now describe expression of T2R38 in tumor cells in patients with pancreatic cancer and in tumor-derived cell lines. T2R38 is localized predominantly intracellular in association with lipid droplets, particularly with the lipid droplet membrane. The receptor can be activated by the bona fide ligand for T2R38, phenylthiourea (PTU), and by N-acetyl-dodecanoyl homoserine (AHL-12), a quorum sensing molecule of Pseudomonas aeruginosa, the latter is the only known natural ligand for T2R38. In response to PTU or AHL-12, key transcription factors are activated including phosphorylation of the MAP kinases p38 and ERK1/2, and upregulation of NFATc1. Moreover, we found increased expression of the multi-drug resistance protein 1 (also known as ABCB1), a transmembrane transporter molecule, participating in shuttling of a plethora of drugs, such as chemotherapeutics or antibiotics. In conclusion, our data indicate a new, additional function of the taste receptor T2R38 beyond sensing ‘bitter’. Moreover, because T2R38 can be stimulated by a bacteria-derived signaling molecule the receptor could link microbiota and cancer.

Anti-inflammatory and antioxidative effects of Camellia oleifera Abel components

Camellia oleifera Abel is a member of Camellia, and its seeds are used to extract Camellia oil, which is generally used as cooking oil in the south of China. Camellia oil consists of unsaturated fatty acids, tea polyphenol, squalene, saponin, carrot element and vitamins, etc. The seed remains after oil extraction of C. oleifera Abel are by-products of oil production, named as Camellia oil cake. Its extracts contain bioactive compounds including sasanquasaponin, flavonoid and tannin. Major components from Camellia oil and its cake have been shown to have anti-inflammatory, antioxidative, antimicrobial and antitumor activities. In this review, we will summarize the latest advance in the studies on anti-inflammatory or antioxidative effects of C. oleifera products, thus providing valuable reference for the future research and development of C. oleifera Abel.

Identification of Epigallocatechin-3- Gallate as an Inhibitor of Phosphoglycerate Mutase 1

Targeting metabolic enzymes is believed to provide new therapeutic opportunities for cancer therapy. Phosphoglycerate mutase 1 (PGAM1) is a glycolytic enzyme that importantly coordinates glycolysis, pentose phosphate pathway (PPP) flux and serine biosynthesis in cancer cells and hence gains increasing interest of inhibitor discovery. Only few PGAM1 inhibitors have been reported and the molecular potency remains very limited. In an effort to discover new PGAM1 inhibitors, we carried out a biochemical assay-based screen that was focused on natural products derived small molecule compounds. (-)-Epigallocatechin-3-gallate (EGCG), the major natural catechins of green tea extract, was identified as a PGAM1 inhibitor that was tremendously more potent than known PGAM1 inhibitors. Further studies combining molecular docking and site-specific mutagenesis revealed that EGCG inhibited PGAM1 enzymatic activity in a manner independent of substrate competition. EGCG modulated the intracellular level of 2-phosphoglycerate, impaired glycolysis and PPP and inhibited proliferation of cancer cells. This study suggested EGCG as a chemical scaffold for the discovery of potent PGAM1 inhibitors and gained mechanistic insights to understand the previously appreciated anticancer properties of EGCG.

Analysis of the expression of human bitter taste receptors in extraoral tissues

The 25 bitter taste receptors (T2Rs) in humans perform a chemosensory function. However, very little is known about the level of expression of these receptors in different tissues. In this study, using nCounter gene expression we analyzed the expression patterns of human TAS2R transcripts in cystic fibrosis bronchial epithelial (CuFi-1), normal bronchial epithelial (NuLi-1), airway smooth muscle (ASM), pulmonary artery smooth muscle (PASM), mammary epithelial, and breast cancer cells. Our results suggest a specific pattern of TAS2R expression with TAS2R3, 4, 5, 10, 13, 19, and 50 transcripts expressed at moderate levels and TAS2R14 and TAS2R20 (or TASR49) at high levels in the various tissues analyzed. This pattern of expression is mostly independent of tissue origin and the pathological state, except in cancer cells. To elucidate the expression at the protein level, we pursued flow cytometry analysis of select T2Rs from CuFi-1 and NuLi-1 cells. The expression levels observed at the gene level by nCounter analysis correlate with the protein levels for the T2Rs analyzed. Next, to assess the functionality of the expressed T2Rs in these cells, we pursued functional assays measuring intracellular calcium mobilization after stimulation with the bitter compound quinine. Using PLC inhibitor, U-73122, we show that the calcium mobilized in these cells predominantly takes place through the Quinine-T2R-Gαβγ-PLC pathway. This report will accelerate studies aimed at analyzing the pathophysiological function of T2Rs in different extraoral tissues.

Resveratrol inhibits Hexokinases II mediated glycolysis in non-small cell lung cancer via targeting Akt signaling pathway

Deregulation of glycolysis was often observed in human cancer cells. In the present study, we reported resveratrol, a small polyphenol, which has been intensively studied in various tumor models, has a profound anti-tumor effect on human non-small cell lung cancer (NSCLC) via regulation of glycolysis. Resveratrol impaired hexokinase II (HK2)-mediated glycolysis, and markedly inhibited anchorage-dependent and -independent growth of NSCLC cells. Exposure to resveratrol decreased EGFR and downstream kinases Akt and ERK1/2 activation. Moreover, we revealed that resveratrol impaired glucose metabolism by mainly inhibiting expression of HK2 mediated by the Akt signaling pathway, and exogenous overexpression of constitutively activated Akt1 in NSCLC cells substantially rescued resveratrol-induced glycolysis suppression. The in vivo data indicated that resveratrol obviously suppressed tumor growth in a xenograft mouse model. Our results suggest targeting HK2 or metabolic enzymes appears to be a new approach for clinical NSCLC prevention or treatment.

Metabonomics applied in exploring the antitumour mechanism of physapubenolide on hepatocellular carcinoma cells by targeting glycolysis through the Akt-p53 pathway

Metabolomics can be used to identify potential markers and discover new targets for future therapeutic interventions. Here, we developed a novel application of the metabonomics method based on gas chromatography-mass spectrometry (GC/MS) analysis and principal component analysis (PCA) for rapidly exploring the anticancer mechanism of physapubenolide (PB), a cytotoxic withanolide isolated from Physalis species. PB inhibited the proliferation of hepatocellular carcinoma cells in vitro and in vivo, accompanied by apoptosis-related biochemical events, including the cleavage of caspase-3/7/9 and PARP. Metabolic profiling analysis revealed that PB disturbed the metabolic pattern and significantly decreased lactate production. This suggests that the suppression of glycolysis plays an important role in the anti-tumour effects induced by PB, which is further supported by the decreased expression of glycolysis-related genes and proteins. Furthermore, the increased level of p53 and decreased expression of p-Akt were observed, and the attenuated glycolysis and enhanced apoptosis were reversed in the presence of Akt cDNA or p53 siRNA. These results confirm that PB exhibits anti-cancer activities through the Akt-p53 pathway. Our study not only reports for the first time the anti-tumour mechanism of PB, but also suggests that PB is a promising therapeutic agent for use in cancer treatments and that metabolomic approaches provide a new strategy to effectively explore the molecular mechanisms of promising anticancer compounds.

In vitro and in vivo study of epigallocatechin-3-gallate-induced apoptosis in aerobic glycolytic hepatocellular carcinoma cells involving inhibition of phosphofructokinase activity

Glycolysis, as an altered cancer cell-intrinsic metabolism, is an essential hallmark of cancer. Phosphofructokinase (PFK) is a metabolic sensor in the glycolytic pathway, and restricting the substrate availability for this enzyme has been researched extensively as a target for chemotherapy. In the present study, we investigated that the effects of epigallocatechin-3-gallate (EGCG), an active component of green tea, on inhibiting cell growth and inducing apoptosis by promoting a metabolic shift away from glycolysis in aerobic glycolytic hepatocellular carcinoma (HCC) cells. EGCG modulated the oligomeric structure of PFK, potentially leading to metabolic stress associated apoptosis and suggesting that EGCG acts by directly suppressing PFK activity. A PFK activity inhibitor enhanced the effect, while the allosteric activator reversed EGCG-induced HCC cell death. PFK siRNA knockdown-induced apoptosis was not reversed by the activator. EGCG enhanced the effect of sorafenib on cell growth inhibition in both aerobic glycolytic HCC cells and in a xenograft mouse model. The present study suggests a potential role for EGCG as an adjuvant in cancer therapy, which merits further investigation at the clinical level.

Chinese Herbs Interfering with Cancer Reprogramming Metabolism

Emerging evidence promotes a reassessment of metabolic reprogramming regulation in cancer research. Although there exists a long history of Chinese herbs applied in cancer treatment, few reports have addressed the effects of Chinese herbal components on metabolic reprogramming, which is a central cancer hallmark involved in the slowing or prevention of chemoresistance in cancer cells. In this review, we have focused on four core elements altered by metabolic reprogramming in cancer cells. These include glucose transport, glycolysis, mitochondrial oxidative phosphorylation, and fatty acid synthesis. With this focus, we have summarized recent advances in metabolic reprogramming of cancer cells in response to specific Chinese herbal components. We propose that exploring Chinese herbal interference in cancer metabolic reprogramming might identify new therapeutic targets for cancer and more ways in which to approach metabolism-related diseases.