Apigenin Restrains Colon Cancer Cell Proliferation via Targeted Blocking of Pyruvate Kinase M2-Dependent Glycolysis

Glycolysis, the sweet appetite of the tumor microenvironment

Cancer cells display an altered metabolic phenotype, characterised by increased glycolysis and lactate production, even in the presence of sufficient oxygen - a phenomenon known as the Warburg effect. This metabolic reprogramming is a crucial adaptation that enables cancer cells to meet their elevated energy and biosynthetic demands. Importantly, the tumor microenvironment plays a pivotal role in shaping and sustaining this metabolic shift in cancer cells. This review explores the intricate relationship between the tumor microenvironment and the Warburg effect, highlighting how communication within this niche regulates cancer cell metabolism and impacts tumor progression and therapeutic resistance. We discuss the potential of targeting the Warburg effect as a promising therapeutic strategy, with the aim of disrupting the metabolic advantage of cancer cells and enhancing our understanding of this complex interplay within the tumor microenvironment.

Potential therapeutic effects of apigenin for colorectal adenocarcinoma: A systematic review and meta-analysis

PURPOSE

Therapeutic management of colorectal cancer (CRC) does not yet yield promising long-term results. Therefore, there is a need for further investigation of possible therapeutic options. Various experiments have studied the effects of apigenin on CRC and have shown conflicting results. This systematic review and meta-analysis investigates the currently existing evidence on the effect of apigenin on CRC.

METHODS

Medline, Embase, Scopus, and Web of Science databases were searched for articles related to apigenin and its effect on CRC in the preclinical setting. Cell viability, growth inhibition, apoptosis, and cell cycle arrest for in-vitro, and body weight, tumor size, and mortality in in-vivo studies were extracted as outcomes.

RESULTS

Thirty-nine articles investigating colorectal adenocarcinoma were included in this meta-analysis. Thirty-seven of these studies had data for in vitro experiments, with eight studies having data for in vivo experiments. Six articles had both in vitro and in vivo assessments. Our analysis showed apigenin reduces cell viability and induces growth inhibition, apoptosis, and cell cycle arrest in in vitro studies. The few in vivo studies indicate that apigenin decreases tumor size while showing no effects on the body weight of animal colorectal adenocarcinoma models.

CONCLUSION

Our results demonstrated that apigenin, through reducing cell viability, inducing growth inhibition, apoptosis, and cell cycle arrest, and also by decreasing the tumor size, can be considered as a possible adjuvant agent in the management of colorectal adenocarcinoma. However, further in vivo studies are needed before any efforts to translate the current evidence into clinical studies.

Transcriptional regulation and post-translational modifications in the glycolytic pathway for targeted cancer therapy

Cancer cells largely rely on aerobic glycolysis or the Warburg effect to generate essential biomolecules and energy for their rapid growth. The key modulators in glycolysis including glucose transporters and enzymes, e.g. hexokinase 2, enolase 1, pyruvate kinase M2, lactate dehydrogenase A, play indispensable roles in glucose uptake, glucose consumption, ATP generation, lactate production, etc. Transcriptional regulation and post-translational modifications (PTMs) of these critical modulators are important for signal transduction and metabolic reprogramming in the glycolytic pathway, which can provide energy advantages to cancer cell growth. In this review we recapitulate the recent advances in research on glycolytic modulators of cancer cells and analyze the strategies targeting these vital modulators including small-molecule inhibitors and microRNAs (miRNAs) for targeted cancer therapy. We focus on the regulation of the glycolytic pathway at the transcription level (e.g., hypoxia-inducible factor 1, c-MYC, p53, sine oculis homeobox homolog 1, N6-methyladenosine modification) and PTMs (including phosphorylation, methylation, acetylation, ubiquitination, etc.) of the key regulators in these processes. This review will provide a comprehensive understanding of the regulation of the key modulators in the glycolytic pathway and might shed light on the targeted cancer therapy at different molecular levels.

"Golgi-customized Trojan horse" nanodiamonds impair GLUT1 plasma membrane localization and inhibit tumor glycolysis

Nutrient or energy deprivation, especially glucose restriction, is a promising anticancer therapeutic approach. However, establishing a precise and potent deprivation strategy remains a formidable task. The Golgi morphology is crucial in maintaining the function of transport proteins (such as GLUT1) driving glycolysis. Thus, in this study, we present a "Golgi-customized Trojan horse" based on tellurium loaded with apigenin (4',5,7-trihydroxyflavone) and human serum albumin, which was able to induce GLUT1 plasma membrane localization disturbance via Golgi dispersal leading to the inhibition of tumor glycolysis. Diamond-shaped delivery system can efficiently penetrate into cells as a gift like Trojan horse, which decomposes into tellurite induced by intrinsically high H2O2 and GSH levels. Consequently, tellurite acts as released warriors causing up to 3.8-fold increase in Golgi apparatus area due to the down-regulation of GOLPH3. Further, this affects GLUT1 membrane localization and glucose transport disturbance. Simultaneously, apigenin hinders ongoing glycolysis and causes significant decrease in ATP level. Collectively, our "Golgi-customized Trojan horse" demonstrates a potent antitumor activity because of its capability to deprive energy resources of cancer cells. This study not only expands the applications of tellurium-based nanomaterials in the biomedicine but also provides insights into glycolysis restriction for anticancer therapy.

MYC Oncogene: A Druggable Target for Treating Cancers with Natural Products

Various diseases, including cancers, age-associated disorders, and acute liver failure, have been linked to the oncogene, MYC. Animal testing and clinical trials have shown that sustained tumor volume reduction can be achieved when MYC is inactivated, and different combinations of therapeutic agents including MYC inhibitors are currently being developed. In this review, we first provide a summary of the multiple biological functions of the MYC oncoprotein in cancer treatment, highlighting that the equilibrium points of the MYC/MAX, MIZ1/MYC/MAX, and MAD (MNT)/MAX complexes have further potential in cancer treatment that could be used to restrain MYC oncogene expression and its functions in tumorigenesis. We also discuss the multifunctional capacity of MYC in various cellular cancer processes, including its influences on immune response, metabolism, cell cycle, apoptosis, autophagy, pyroptosis, metastasis, angiogenesis, multidrug resistance, and intestinal flora. Moreover, we summarize the MYC therapy patent landscape and emphasize the potential of MYC as a druggable target, using herbal medicine modulators. Finally, we describe pending challenges and future perspectives in biomedical research, involving the development of therapeutic approaches to modulate MYC or its targeted genes. Patients with cancers driven by MYC signaling may benefit from therapies targeting these pathways, which could delay cancerous growth and recover antitumor immune responses.

Targeting the Metabolic Paradigms in Cancer and Diabetes

Dysregulated metabolic dynamics are evident in both cancer and diabetes, with metabolic alterations representing a facet of the myriad changes observed in these conditions. This review delves into the commonalities in metabolism between cancer and type 2 diabetes (T2D), focusing specifically on the contrasting roles of oxidative phosphorylation (OXPHOS) and glycolysis as primary energy-generating pathways within cells. Building on earlier research, we explore how a shift towards one pathway over the other serves as a foundational aspect in the development of cancer and T2D. Unlike previous reviews, we posit that this shift may occur in seemingly opposing yet complementary directions, akin to the Yin and Yang concept. These metabolic fluctuations reveal an intricate network of underlying defective signaling pathways, orchestrating the pathogenesis and progression of each disease. The Warburg phenomenon, characterized by the prevalence of aerobic glycolysis over minimal to no OXPHOS, emerges as the predominant metabolic phenotype in cancer. Conversely, in T2D, the prevailing metabolic paradigm has traditionally been perceived in terms of discrete irregularities rather than an OXPHOS-to-glycolysis shift. Throughout T2D pathogenesis, OXPHOS remains consistently heightened due to chronic hyperglycemia or hyperinsulinemia. In advanced insulin resistance and T2D, the metabolic landscape becomes more complex, featuring differential tissue-specific alterations that affect OXPHOS. Recent findings suggest that addressing the metabolic imbalance in both cancer and diabetes could offer an effective treatment strategy. Numerous pharmaceutical and nutritional modalities exhibiting therapeutic effects in both conditions ultimately modulate the OXPHOS-glycolysis axis. Noteworthy nutritional adjuncts, such as alpha-lipoic acid, flavonoids, and glutamine, demonstrate the ability to reprogram metabolism, exerting anti-tumor and anti-diabetic effects. Similarly, pharmacological agents like metformin exhibit therapeutic efficacy in both T2D and cancer. This review discusses the molecular mechanisms underlying these metabolic shifts and explores promising therapeutic strategies aimed at reversing the metabolic imbalance in both disease scenarios.

A comprehensive view on the apigenin impact on colorectal cancer: Focusing on cellular and molecular mechanisms

Colon cancer (CC) is one of the most common and deadly cancers worldwide. Oncologists are facing challenges such as development of drug resistance and lack of suitable drug options for CC treatment. Flavonoids are a group of natural compounds found in fruits, vegetables, and other plant-based foods. According to research, they have a potential role in the prevention and treatment of cancer. Apigenin is a flavonoid that is present in many fruits and vegetables. It has been used as a natural antioxidant for a long time and has been considered due to its anticancer effects and low toxicity. The results of this review study show that apigenin has potential anticancer effects on CC cells through various mechanisms. In this comprehensive review, we present the cellular targets and signaling pathways of apigenin indicated to date in in vivo and in vitro CC models. Among the most important modulated pathways, Wnt/β-catenin, PI3K/AKT/mTOR, MAPK/ERK, JNK, STAT3, Bcl-xL and Mcl-1, PKM2, and NF-kB have been described. Furthermore, apigenin suppresses the cell cycle in G2/M phase in CC cells. In CC cells, apigenin-induced apoptosis is increased by inhibiting the formation of autophagy. According to the results of this study, apigenin appears to have the potential to be a promising agent for CC therapy, but more research is required in the field of pharmacology and pharmacokinetics to establish the apigenin effects and its dosage for clinical studies.

The interaction between apigenin and PKM2 restrains progression of colorectal cancer

Apigenin, a flavonoid that widely existed in vegetables and fruits, possesses anticarcinogenic, low toxicity, and no mutagenic properties, suggesting that apigenin is a potential therapeutic agent for tumors. However, the underlying anti-cancer molecular target of apigenin is still unclear. Therefore, to reveal the direct target and amino acid site of apigenin against colorectal cancer is the focus of this study. In the present study, the results proved that the anti-CRC activity of apigenin was positively correlated with pyruvate kinase M2 (PKM2) expression, characterized by the inhibition of cell proliferation and increase of apoptotic effects induced by apigenin in LS-174T cells of knock down PKM2. Next, pull-down and MALDI-TOF/TOF analysis determined that apigenin might interact directly with PKM2 in HCT-8 cells. Further, the study confirmed that lysine residue 433 (K433) was a key amino acid site for PKM2 binding to apigenin. Apigenin restricted the glycolysis of LS-174T and HCT-8 cells by targeting the K433 site of PKM2, thereby playing an anti-CRC role in vivo and in vitro. Meanwhile, apigenin markedly attenuated tumor growth without any adverse effects. Taken together, these findings reveal that apigenin is worthy of consideration as a promising PKM2 inhibitor for the prevention of CRC.

Phytochemicals targeting glycolysis in colorectal cancer therapy: effects and mechanisms of action

Colorectal cancer (CRC) is the third most common malignant tumor in the world, and it is prone to recurrence and metastasis during treatment. Aerobic glycolysis is one of the main characteristics of tumor cell metabolism in CRC. Tumor cells rely on glycolysis to rapidly consume glucose and to obtain more lactate and intermediate macromolecular products so as to maintain growth and proliferation. The regulation of the CRC glycolysis pathway is closely associated with several signal transduction pathways and transcription factors including phosphatidylinositol 3-kinases/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR), adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), hypoxia-inducible factor-1 (HIF-1), myc, and p53. Targeting the glycolytic pathway has become one of the key research aspects in CRC therapy. Many phytochemicals were shown to exert anti-CRC activity by targeting the glycolytic pathway. Here, we review the effects and mechanisms of phytochemicals on CRC glycolytic pathways, providing a new method of drug development.

Development of isoselenazolium chlorides as selective pyruvate kinase isoform M2 inhibitors

Alterations in cancer metabolic pathways open up an opportunity for targeted and effective elimination of tumor cells. Pyruvate kinase M2 (PKM2) is predominantly expressed in proliferating cells and plays an essential role in directing glucose metabolism in cancer. Here, we report the design of novel class of selective PKM2 inhibitors as anti-cancer agents and their mechanism of action. Compound 5c being the most active with IC₅₀ = 0.35 ± 0.07 μM, also downregulates PKM2 mRNA expression, modulates mitochondrial functionality, induces oxidative burst and is cytotoxic for various cancer types. Isoselenazolium chlorides have an unusual mechanism of PKM2 inhibition, inducing a functionally deficient tetrameric assembly, while exhibiting a competitive inhibitor character. The discovery of robust PKM2 inhibitors not only offers candidates for anticancer therapy but is also crucial for studying the role of PKM2 in cancer.

Flavonoids nanostructures promising therapeutic efficiencies in colorectal cancer

Colorectal cancer is among the frequently diagnosed cancers with high mortality rates around the world. Polyphenolic compounds such as flavonoids are secondary plant metabolites which exhibit anti-cancer activities along with anti-inflammatory effects. However, due to their hydrophobicity, sensitivity to degradation and low bioavailability, therapeutic effects have shown poor therapeutic effect. Nano delivery systems such as nanoliposomes, nanomicelles, silica nanoparticles have been investigated to overcome these difficulties. This review provides a summary of the efficiency of certain flavonoids and polyphenols (apigenin, genistein, resveratrol, quercetin, silymarin, catechins, luteolin, fisetin, gallic acid, rutin, and curcumin) on colorectal cancer models. It comprehensively discusses the influence of nano-formulation of flavonoids on their biological functions, including cellular uptake rate, bioavailability, solubility, and cytotoxicity, as well as their potential for reducing colorectal cancer tumor size under in vivo situations.

Flavonoids attenuate cancer metabolism by modulating Lipid metabolism, amino acids, ketone bodies and redox state mediated by Nrf2

Metabolic reprogramming of cancer cells is a common hallmark of malignant transformation. The preference for aerobic glycolysis over oxidative phosphorylation in tumors is a well-studied phenomenon known as the Warburg effect. Importantly, metabolic transformation of cancer cells also involves alterations in signaling cascades contributing to lipid metabolism, amino acid flux and synthesis, and utilization of ketone bodies. Also, redox regulation interacts with metabolic reprogramming during malignant transformation. Flavonoids, widely distributed phytochemicals in plants, exert various beneficial effects on human health through modulating molecular cascades altered in the pathological cancer phenotype. Recent evidence has identified numerous flavonoids as modulators of critical components of cancer metabolism and associated pathways interacting with metabolic cascades such as redox balance. Flavonoids affect lipid metabolism by regulating fatty acid synthase, redox balance by modulating nuclear factor-erythroid factor 2-related factor 2 (Nrf2) activity, or amino acid flux and synthesis by phosphoglycerate mutase 1. Here, we discuss recent preclinical evidence evaluating the impact of flavonoids on cancer metabolism, focusing on lipid and amino acid metabolic cascades, redox balance, and ketone bodies.

Role of Plant-Derived Flavonoids in Cancer Treatment

Flavonoids are polyphenolic phytochemicals, which occur naturally in plants and possess both anti-oxidant and pro-oxidant properties. Flavonoids are gaining increasing popularity in the pharmaceutical industry as healthy and cost-effective compounds. Flavonoids show beneficial pharmacological activities in the treatment and prevention of various types of diseases. They are natural and less toxic agents for cancer chemotherapy and radiotherapy via regulation of multiple cell signaling pathways and pro-oxidant effects. In this review, we have summarized the mechanisms of action of selected flavonoids, and their pharmacological implications and potential therapeutic applications in cancer therapy.

The PTBP1‑NCOA4 axis promotes ferroptosis in liver cancer cells

Polypyrimidine tract‑binding protein 1 (PTBP1) plays an important role in tumor immunity, cell proliferation, apoptosis, and autophagy by regulating RNA metabolism. However, the specific function and mechanism of PTBP1 in ferroptosis remain unclear. In the present study, it was investigated whether PTBP1 regulates ferroptosis and the exact mechanism. The iron, malondialdehyde (MDA), and GSH levels were detected in sorafenib (SF)‑treated liver cancer cells. si‑PTBP1 introduction into SF‑treated liver cancer cells resulted in a significant reduction in the levels of MDA and iron. Additionally, a significant recovery of GSH levels was observed after silencing PTBP1. StarBase v2.0 database was used to predict potential transcripts that can physically interact with PTBP1 and nuclear receptor coactivator 4 (NCOA4) mRNA was identified as the most enriched binding partner in the PTBP1‑RNA complex. A dual‑luciferase assay then demonstrated that PTBP1 directly interacted with NCOA4. PTBP1 silencing did not affect NCOA4 stability following treatment with cycloheximide. A pull‑down assay revealed that the PTBP1‑binding region was in the 5'‑UTR of the NCOA4 mRNA sequence. These results suggest that PTBP1 mediates ferroptosis in liver cancer cells by regulating NCOA4 translation. In vivo experiments reconfirmed the role of the PTBP1‑NCOA4 axis in a xenograft transplantation model. It was observed that the mean tumor weight increased after PTBP1 knockout. In conclusion, silencing of PTBP1 decreased the sensitivity of liver cancer cells to ferroptosis after SF treatment and regulated ferritinophagy by mediating NCOA4 translation.

The Preparation of Apigenin Nanoparticles and the Study of Their Anti-Inflammatory and Anti-Tumor Activities In Vitro

Apigenin (API) has many biological activities, but its poor solubility limits its clinical application. In this research, API nanoparticles were prepared by the liquid antisolvent precipitation (LAP) technique, which effectively improved the solubility and bioavailability of API. Through the design of a single-factor test, the effects of the type and dosage of surfactants, API concentration, the antisolvent to solvent volume ratio, the speed and time of stirring, the temperature of precipitation, and the dropping speed on the MPS (mean particle size) of API nanosuspension were carried out. The optimum technological conditions were determined as follows: 5 mg/mL of tween 80 as a surfactant, 20 mg/mL of API, an antisolvent/solvent volume ratio of 10, a 1200 r/min stirring speed for 5 min, a 45 °C precipitation temperature, and a 1 mL/min dropping speed. Under the optimum conditions, we obtained API nanosuspension with 170.5 nm MPS and then it was freeze-dried to obtain the API nanoparticles. Moreover, we characterized the API nanoparticles by SEM, FTIR, XRD, DSC, and TG. Results showed that although API nanoparticles transformed into an amorphous form, their internal chemical structure had not been changed and had a higher solubility. Finally, API nanoparticles’ anti-inflammatory activities were evaluated by observing the effect of API on nitric oxide (NO) production and IL-10 production toward RAW264.7 cells induced by lipopolysaccharide (LPS). Moreover, the anti-tumor effect of API was determined by testing cell viability and apoptosis. The results suggested that API nanoparticles exhibited much better anti-inflammatory and anti-tumor activities compared to raw API.

Why Do Dietary Flavonoids Have a Promising Effect as Enhancers of Anthracyclines? Hydroxyl Substituents, Bioavailability and Biological Activity

Anthracyclines currently play a key role in the treatment of many cancers, but the limiting factor of their use is the widespread phenomenon of drug resistance and untargeted toxicity. Flavonoids have pleiotropic, beneficial effects on human health that, apart from antioxidant activity, are currently considered small molecules-starting structures for drug development and enhancers of conventional therapeutics. This paper is a review of the current and most important data on the participation of a selected series of flavonoids: chrysin, apigenin, kaempferol, quercetin and myricetin, which differ in the presence of an additional hydroxyl group, in the formation of a synergistic effect with anthracycline antibiotics. The review includes a characterization of the mechanism of action of flavonoids, as well as insight into the physicochemical parameters determining their bioavailability in vitro. The crosstalk between flavonoids and the molecular activity of anthracyclines discussed in the article covers the most important common areas of action, such as (1) disruption of DNA integrity (genotoxic effect), (2) modulation of antioxidant response pathways, and (3) inhibition of the activity of membrane proteins responsible for the active transport of drugs and xenobiotics. The increase in knowledge about the relationship between the molecular structure of flavonoids and their biological effect makes it possible to more effectively search for derivatives with a synergistic effect with anthracyclines and to develop better therapeutic strategies in the treatment of cancer.

Natural products targeting glycolytic signaling pathways-an updated review on anti-cancer therapy

Glycolysis is a complex metabolic process that occurs to convert glucose into pyruvate to produce energy for living cells. Normal cells oxidized pyruvate into adenosine triphosphate and carbon dioxide in the presence of oxygen in mitochondria while cancer cells preferentially metabolize pyruvate to lactate even in the presence of oxygen in order to maintain a slightly acidic micro-environment of PH 6.5 and 6.9, which is beneficial for cancer cell growth and metastasis. Therefore targeting glycolytic signaling pathways provided new strategy for anti-cancer therapy. Natural products are important sources for the treatment of diseases with a variety of pharmacologic activities. Accumulated studies suggested that natural products exhibited remarkable anti-cancer properties both in vitro and in vivo. Plenty of studies suggested natural products like flavonoids, terpenoids and quinones played anti-cancer properties via inhibiting glucose metabolism targets in glycolytic pathways. This study provided an updated overview of natural products controlling glycolytic pathways, which also provide insight into druggable mediators discovery targeting cancer glucose metabolism.

The Potential Role of Apigenin in Cancer Prevention and Treatment

Cancer is the leading cause of death worldwide. In spite of advances in the treatment of cancer, currently used treatment modules including chemotherapy, hormone therapy, radiation therapy and targeted therapy causes adverse effects and kills the normal cells. Therefore, the goal of more effective and less side effects-based cancer treatment approaches is still at the primary position of present research. Medicinal plants or their bioactive ingredients act as dynamic sources of drugs due to their having less side effects and also shows the role in reduction of resistance against cancer therapy. Apigenin is an edible plant-derived flavonoid that has received significant scientific consideration for its health-promoting potential through modulation of inflammation, oxidative stress and various other biological activities. Moreover, the anti-cancer potential of apigenin is confirmed through its ability to modulate various cell signalling pathways, including tumor suppressor genes, angiogenesis, apoptosis, cell cycle, inflammation, apoptosis, PI3K/AKT, NF-κB, MAPK/ERK and STAT3 pathways. The current review mainly emphases the potential role of apigenin in different types of cancer through the modulation of various cell signaling pathways. Further studies based on clinical trials are needed to explore the role of apigenin in cancer management and explain the possible potential mechanisms of action in this vista.

Cancer metabolism control by natural products: Pyruvate kinase M2 targeting therapeutics

Glycolysis is the primary source of energy for cancer growth and metastasis. The shift in metabolism from mitochondrial oxidative phosphorylation to aerobic glycolysis is called the Warburg effect. Cancer progression due to aerobic glycolysis is often associated with the activation of oncogenes or the loss of tumor suppressors. Therefore, inhibition of glycolysis is one of the effective strategies in cancer control. Pyruvate kinase M2 (PKM2) is a key glycolytic enzyme overexpressed in breast, prostate, lung, colorectal, and liver cancers. Here, we discuss published studies regarding PKM2 inhibitors from natural products that are promising drug candidates for cancer therapy. We have highlighted the potential of natural PKM2 inhibitors for various cancer types. Moreover, we encourage researchers to evaluate the combinational effects between natural and synthetic PKM2 inhibitors. Also, further high-quality studies are needed to firmly establish the clinical efficacy of natural products.

Phytochemicals as Regulators of Tumor Glycolysis and Hypoxia Signaling Pathways: Evidence from In Vitro Studies

The full understanding of the complex nature of cancer still faces many challenges, as cancers arise not as a result of a single target disruption but rather involving successive genetic and epigenetic alterations leading to multiple altered metabolic pathways. In this light, the need for a multitargeted, safe and effective therapy becomes essential. Substantial experimental evidence upholds the potential of plant-derived compounds to interfere in several important pathways, such as tumor glycolysis and the upstream regulating mechanisms of hypoxia. Herein, we present a comprehensive overview of the natural compounds which demonstrated, in vitro studies, an effective anticancer activity by affecting key regulators of the glycolytic pathway such as glucose transporters, hexokinases, phosphofructokinase, pyruvate kinase or lactate dehydrogenase. Moreover, we assessed how phytochemicals could interfere in HIF-1 synthesis, stabilization, accumulation, and transactivation, emphasizing PI3K/Akt/mTOR and MAPK/ERK pathways as important signaling cascades in HIF-1 activation. Special consideration was given to cell culture-based metabolomics as one of the most sensitive, accurate, and comprising approaches for understanding the response of cancer cell metabolome to phytochemicals.

Evidence for Anticancer Effects of Chinese Medicine Monomers on Colorectal Cancer

Colorectal cancer is one of the most commonly occurring cancers worldwide. Although clinical reports have indicated the anticancer effects of Chinese herbal medicine, the multiple underlying molecular and biochemical mechanisms of action remain to be fully characterized. Chinese medicine (CM) monomers, which are the active components of CM, serve as the material basis of the functional mechanisms of CM. The aim of this review is to summarize the current experimental evidence from in vitro, in vivo, and clinical studies for the effects of CM monomers in colorectal cancer prevention and treatment, providing some useful references for future research.

Targeting lactate metabolism and glycolytic pathways in the tumor microenvironment by natural products: A promising strategy in combating cancer

Anticancer drugs are not purely effective because of their toxicity, side effects, high cost, inaccessibility, and associated resistance. On the other hand, cancer is a complex public health problem that could intelligently adopt different signaling pathways and alter the body's metabolism to escape from the immune system. One of the cancer strategies to metastasize is modifying pH in the tumor microenvironment, ranging between 6.5 and 6.9. As a powerful determiner, lactate is responsible for this acidosis. It is involved in immune stimulation, including innate and adaptive immunity, apoptotic-related factors (Bax/Bcl-2, caspase), and glycolysis pathways (e.g., GLUT-1, PKM2, PFK, HK2, MCT-1, and LDH). Lactate metabolism, in turn, is interconnected with several dysregulated signaling mediators, including PI3K/Akt/mTOR, AMPK, NF-κB, Nrf2, JAK/STAT, and HIF-1α. Because of lactate's emerging and critical role, targeting lactate production and its transporters is important for preventing and managing tumorigenesis. Hence, exploring and developing novel promising anticancer agents to minimize human cancers is urgent. Based on numerous studies, natural secondary metabolites as multi-target alternative compounds with health-promoting properties possess more high effectiveness and low side effects than conventional agents. Besides, the mechanism of multi-targeted natural sources is related to lactate production and cancer-associated cross-talked factors. This review focuses on targeting the lactate metabolism/transporters, and lactate-associated mediators, including glycolytic pathways. Besides, interconnected mediators to lactate metabolism are also targeted by natural products. Accordingly, plant-derived secondary metabolites are introduced as alternative therapies in combating cancer through modulating lactate metabolism and glycolytic pathways.

A Perspective on Medicinal Chemistry Approaches for Targeting Pyruvate Kinase M2

The allosteric regulation of pyruvate kinase M2 (PKM2) affects the switching of the PKM2 protein between the high-activity and low-activity states that allow ATP and lactate production, respectively. PKM2, in its low catalytic state (dimeric form), is chiefly active in metabolically energetic cells, including cancer cells. More recently, PKM2 has emerged as an attractive target due to its role in metabolic dysfunction and other interrelated conditions. PKM2 (dimer) activity can be inhibited by modulating PKM2 dimer-tetramer dynamics using either PKM2 inhibitors that bind at the ATP binding active site of PKM2 (dimer) or PKM2 activators that bind at the allosteric site of PKM2, thus activating PKM2 from the dimer formation to the tetrameric formation. The present perspective focuses on medicinal chemistry approaches to design and discover PKM2 inhibitors and activators and further provides a scope for the future design of compounds targeting PKM2 with better efficacy and selectivity.

Novel imidazopyrimidines-based molecules induce tetramerization of tumor pyruvate kinase M2 and exhibit potent antiproliferative profile

Discovery of novel and potent lead molecules for the specific therapeutic targets by de novo drug design is still in infancy. Here, we disclose the unprecedented development of imidazopyri(mi)dine-based tumor pyruvate kinase M2 (PKM2) modulators by subsequent link and grow strategy. The most potent modulator 15n acts as a PKM2 activator with an AC₅₀ of 90 nM, with considerable cancer cell-selectivity and membrane-permeability. NMR metabolomics studies also revealed that treatment with 15n results in diminution in lactate concentrations in MCF-7 cells. 15n binds to a previously reported site at PKM2 adjacent to the interface of two monomers. In molecular dynamics (MD) simulation studies, it was observed that 15n stabilizes the PKM2 at the dimeric interface, assisting in the formation of a biologically active tetramer conformation. 15n was also screened on MCF-7 breast cancer cell lines grown on 3-D scaffolds, and the results exhibited better anticancer potential compared to control, paving the way for future clinical studies.

Kinetic Characterization and Inhibitor Screening of Pyruvate Kinase I From Babesia microti

The apicomplexan Babesia microti is a main pathogenic parasite causing human babesiosis, which is one of the most widely distributed tick-borne diseases in humans. Pyruvate kinase (PYK) plays a central metabolic regulatory role in most living organisms and catalyzes the essentially irreversible step in glycolysis that converts phosphoenolpyruvate (PEP) to pyruvate. Hence, PYK is recognized as an attractive therapeutic target in cancer and human pathogens such as apicomplexans. In this study, we cloned, expressed, and purified B. microti PYK I (BmPYKI). Western blotting illustrated that anti-rBmPYKI antibody could specifically recognize the native BmPYKI protein in the lysate of B. microti with a 54-kDa band, which is consistent with the predicted size. In addition, the enzymatic activity of the purified recombinant PYKI (rPYKI) was tested under a range of pH values. The results showed that the maximum catalytic activity could be achieved at pH 7.0. The saturation curves for substrates demonstrated that the K_m value for PEP was 0.655 ± 0.117 mM and that for ADP was 0.388 ± 0.087 mM. We further investigated the effect of 13 compounds on rBmPYKI. Kinetic analysis indicated that six inhibitors (tannic acid, shikonin, apigenin, PKM2 inhibitor, rosiglitazone, and pioglitazone) could significantly inhibit the catalytic activity of PYKI, among which tannic acid is the most efficient inhibitor with an IC₅₀ value 0.49 μM. Besides, four inhibitors (tannic acid, apigenin, shikonin, and PKM2 inhibitor) could significantly decrease the growth of in vitro-cultured B. microti with IC₅₀ values of 0.77, 2.10, 1.73, and 1.15 μM. Overall, the present study provides a theoretical basis for the design and development of new anti-Babesia drugs.

Protective Effects of Flavonoids Against Mitochondriopathies and Associated Pathologies: Focus on the Predictive Approach and Personalized Prevention

Multi-factorial mitochondrial damage exhibits a “vicious circle” that leads to a progression of mitochondrial dysfunction and multi-organ adverse effects. Mitochondrial impairments (mitochondriopathies) are associated with severe pathologies including but not restricted to cancers, cardiovascular diseases, and neurodegeneration. However, the type and level of cascading pathologies are highly individual. Consequently, patient stratification, risk assessment, and mitigating measures are instrumental for cost-effective individualized protection. Therefore, the paradigm shift from reactive to predictive, preventive, and personalized medicine (3PM) is unavoidable in advanced healthcare. Flavonoids demonstrate evident antioxidant and scavenging activity are of great therapeutic utility against mitochondrial damage and cascading pathologies. In the context of 3PM, this review focuses on preclinical and clinical research data evaluating the efficacy of flavonoids as a potent protector against mitochondriopathies and associated pathologies.

Potential of olive oil and its phenolic compounds as therapeutic intervention against colorectal cancer: a comprehensive review

Colorectal cancer (CRC) is one of the major causes of death across the world and incidence rate of CRC increasing alarmingly each passing year. Diet, genomic anomalies, inflammation and deregulated signalling pathways are among the major causes of CRC. Because of numerous side effects of CRC therapies available now, researchers all over the world looking for alternative treatment/preventive strategy with lesser/no side effects. Olive oil which is part of Mediterranean diet contains numerous phenolic compounds that fight against free radicals and inflammation and also well-known for protective role against CRC. The current review focused on the recent evidences where olive oil and its phenolic compounds such as hydroxytyrosol, oleuropein and oleocanthal showed activities against CRC as well to analyse the cellular and molecular signalling mechanism through which these compounds act on. These compounds shown to combat CRC by reducing proliferation, migration, invasion and angiogenesis through regulation of numerous signalling pathways including MAPK pathway, PI3K-Akt pathway and Wnt/β-catenin pathway and at the same time, induce apoptosis in different CRC model. However, further research is an absolute necessity to establish these compounds as nutritional supplements and develop therapeutic strategy in CRC.

Tumor pyruvate kinase M2 modulators: a comprehensive account of activators and inhibitors as anticancer agents

Pyruvate kinase M2 (PKM2) catalyzes the conversion of phosphoenolpyruvate (PEP) to pyruvate. It plays a central role in the metabolic reprogramming of cancer cells and is expressed in most human tumors. It is essential in indiscriminate proliferation, survival, and tackling apoptosis in cancer cells. This positions PKM2 as a hot target in cancer therapy. Despite its well-known structure and several reported modulators targeting PKM2 as activators or inhibitors, a comprehensive review focusing on such modulators is lacking. Herein we summarize modulators of PKM2, the assays used to detect their potential, the preferable tense (T) and relaxed (R) states in which the enzyme resides, lacunae in existing modulators, and several strategies that may lead to effective anticancer drug development targeting PKM2.

Oxygen sensing, mitochondrial biology and experimental therapeutics for pulmonary hypertension and cancer

The homeostatic oxygen sensing system (HOSS) optimizes systemic oxygen delivery. Specialized tissues utilize a conserved mitochondrial sensor, often involving NDUFS2 in complex I of the mitochondrial electron transport chain, as a site of pO₂-responsive production of reactive oxygen species (ROS). These ROS are converted to a diffusible signaling molecule, hydrogen peroxide (H₂O₂), by superoxide dismutase (SOD2). H₂O₂ exits the mitochondria and regulates ion channels and enzymes, altering plasma membrane potential, intracellular Ca²⁺ and Ca²⁺-sensitization and controlling acute, adaptive, responses to hypoxia that involve changes in ventilation, vascular tone and neurotransmitter release. Subversion of this O₂-sensing pathway creates a pseudohypoxic state that promotes disease progression in pulmonary arterial hypertension (PAH) and cancer. Pseudohypoxia is a state in which biochemical changes, normally associated with hypoxia, occur despite normal pO₂. Epigenetic silencing of SOD2 by DNA methylation alters H₂O₂ production, activating hypoxia-inducible factor 1α, thereby disrupting mitochondrial metabolism and dynamics, accelerating cell proliferation and inhibiting apoptosis. Other epigenetic mechanisms, including dysregulation of microRNAs (miR), increase pyruvate dehydrogenase kinase and pyruvate kinase muscle isoform 2 expression in both diseases, favoring uncoupled aerobic glycolysis. This Warburg metabolic shift also accelerates cell proliferation and impairs apoptosis. Disordered mitochondrial dynamics, usually increased mitotic fission and impaired fusion, promotes disease progression in PAH and cancer. Epigenetic upregulation of dynamin-related protein 1 (Drp1) and its binding partners, MiD49 and MiD51, contributes to the pathogenesis of PAH and cancer. Finally, dysregulation of intramitochondrial Ca²⁺, resulting from impaired mitochondrial calcium uniporter complex (MCUC) function, links abnormal mitochondrial metabolism and dynamics. MiR-mediated decreases in MCUC function reduce intramitochondrial Ca²⁺, promoting Warburg metabolism, whilst increasing cytosolic Ca²⁺, promoting fission. Epigenetically disordered mitochondrial O₂-sensing, metabolism, dynamics, and Ca²⁺ homeostasis offer new therapeutic targets for PAH and cancer. Promoting glucose oxidation, restoring the fission/fusion balance, and restoring mitochondrial calcium regulation are promising experimental therapeutic strategies.

Phytocompounds Targeting Metabolic Reprogramming in Cancer: An Assessment of Role, Mechanisms, Pathways, and Therapeutic Relevance

The metabolism of cancer is remarkably different from that of normal cells and confers a variety of benefits, including the promotion of other cancer hallmarks. As the rewired metabolism is a near-universal property of cancer cells, efforts are underway to exploit metabolic vulnerabilities for therapeutic benefits. In the continued search for safer and effective ways of cancer treatment, structurally diverse plant-based compounds have gained substantial attention. Here, we present an extensive assessment of the role of phytocompounds in modulating cancer metabolism and attempt to make a case for the use of plant-based compounds in targeting metabolic vulnerabilities of cancer. We discuss the pharmacological interactions of phytocompounds with major metabolic pathways and evaluate the role of phytocompounds in the regulation of growth signaling and transcriptional programs involved in the metabolic transformation of cancer. Lastly, we examine the potential of these compounds in the clinical management of cancer along with limitations and challenges.

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.

Does Oral Apigenin Have Real Potential for a Therapeutic Effect in the Context of Human Gastrointestinal and Other Cancers?

Apigenin (4′, 5, 7-trihydroxyflavone) is a plant flavone that has been found to have various actions against cancer cells. We evaluated available evidence to determine whether it is feasible for apigenin to have such effects in human patients.

Apigenin taken orally is systemically absorbed and recirculated by enterohepatic and local intestinal pathways. Its bioavailability is in the region of 30%. Once absorbed from the oral route it reaches maximal circulating concentration (C_max) after a time (T_max) of 0.5–2.5h, with an elimination half-life (T¹/₂) averaging 2.52 ± 0.56h.

Using a circulating concentration for efficacy of 1–5μmol/L as the target, we evaluated data from both human and rodent pharmacokinetic studies to determine if a therapeutic concentration would be feasible. We find that oral intake of dietary materials would require heroic ingestion amounts and is not feasible. However, use of supplements of semi-purified apigenin in capsule form could reach target blood levels using amounts that are within the range currently acceptable for other supplements and medications. Modified formulations or parenteral injection are suitable but may not be necessary.

Further work with direct studies of pharmacokinetics and clinical outcomes are necessary to fully evaluate whether apigenin will contribute to a useful clinical strategy, but given emerging evidence that it may interact beneficially with chemotherapeutic drugs, this is worthy of emphasis. In addition, more effective access to intestinal tissues from the oral route raises the possibility that apigenin may be of particular relevance to gastrointestinal disorders including colorectal cancer.

Ethanol-assisted kneading of apigenin with arginine for enhanced dissolution rate of apigenin: development of rapidly disintegrating tablets

Apigenin is a natural flavonoid which is claimed to have many pharmacological activities ranging from simple anti-inflammatory to anticancer action. However, poor dissolution slowed the advancement of this drug through the development pipelines. The objective of this work was to probe ethanol-aided kneading of apigenin with arginine as a new strategy for enhanced dissolution rate. The work was extended to develop rapidly disintegrating tablets of apigenin. Apigenin was mixed with increasing molar ratios of arginine before ethanol-aided kneading. The resulting products were examined using Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction in addition to probing the dissolution characteristics of apigenin. The analytical techniques highlighted the existence of new crystalline species with a possibility of salt formation. The recorded alterations in the crystalline properties were associated with a significant enhancement in the dissolution rate of apigenin. The presence of arginine did not have any negative effect of the cytotoxic power of apigenin. Optimum formulation was successfully prepared as rapidly disintegrating tablets which showed fast liberation of apigenin. The study introduced arginine as a potential excipient for enhanced dissolution of apigenin after ethanol-assisted kneading.

Isovitexin potentiated the antitumor activity of cisplatin by inhibiting the glucose metabolism of lung cancer cells and reduced cisplatin-induced immunotoxicity in mice

The increased resistance and toxicity have become the main causes of chemotherapy failure for treating lung cancer. The combination of chemotherapeutic drugs with other agents has been recognized as a promising strategy to overcome these difficulties. Isovitexin (IVT) is a well-known flavone C-glycoside found in many plants and has attracted wide attention due to its obvious antitumor and antioxidant effects. In this study, we investigated the synergistic effects of IVX and cisplatin (DDP) in non-small cell lung cancer (NSCLC) A549 and H1975 cells. The results showed that the combined treatment with IVT and DDP markedly inhibited proliferation and induced apoptosis of the two NSCLC cells. Using a mouse model of A549 xenograft, IVT potentiated the inhibition of DDP on tumor growth, but reduced DDP-induced hepatotoxicity and nephrotoxicity in mice. Remarkedly, IVT promoted lipopolysaccharide (LPS)- and lectin- stimulated splenocyte proliferation, and enhance cytotoxic T lymphocyte (CTL) and natural killer (NK) cell activities as well as the production of IL-2 and TNF-α. Furthermore, IVT significantly reduced glucose uptake, lactate production, and ATP production, and downregulated the protein expressions of pyruvate kinase M2 (PKM2)-mediated pathway in both A549 and H1975 cells. After the over-expression of PKM2 in the NSCLC cells, the synergistic antitumor effect of IVT and DDP was markedly weakened. Therefore, IVT not only inhibited cell proliferation and glucose metabolism via downregulating the expression of PKM2 to enhance the antitumor activity of DDP against lung cancer cells, and improved DDP-induced immunotoxicity in mice. It also presented a novel strategy to enhance the anti-tumor effect of platinum-based chemotherapy against NSCLC.

The Hallmarks of Flavonoids in Cancer

Flavonoids represent an important group of bioactive compounds derived from plant-based foods and beverages with known biological activity in cells. From the modulation of inflammation to the inhibition of cell proliferation, flavonoids have been described as important therapeutic adjuvants against several diseases, including diabetes, arteriosclerosis, neurological disorders, and cancer. Cancer is a complex and multifactor disease that has been studied for years however, its prevention is still one of the best known and efficient factors impacting the epidemiology of the disease. In the molecular and cellular context, some of the mechanisms underlying the oncogenesis and the progression of the disease are understood, known as the hallmarks of cancer. In this text, we review important molecular signaling pathways, including inflammation, immunity, redox metabolism, cell growth, autophagy, apoptosis, and cell cycle, and analyze the known mechanisms of action of flavonoids in cancer. The current literature provides enough evidence supporting that flavonoids may be important adjuvants in cancer therapy, highlighting the importance of healthy and balanced diets to prevent the onset and progression of the disease.

Mechanism of Interactions of dsDNA Binding with Apigenin and Its Sulfamate Derivatives Using Multispectroscopic, Voltammetric, and Molecular Docking Studies

DNA binding investigations are critical for designing better pharmaceutical compounds since the binding of a compound to dsDNA in the minor groove is critical in drug discovery. Although only one in vitro study on the DNA binding mode of apigenin (APG) has been conducted, there have been no electrochemical and theoretical studies reported. We hereby report the mechanism of binding interaction of APG and a new class of sulfonamide-modified flavonoids, apigenin disulfonamide (ADSAM) and apigenin trisulfonamide (ATSAM), with deoxyribonucleic acid (DNA). This study was conducted using multispectroscopic instrumentation techniques, which include UV-vis absorption, thermal denaturation, fluorescence, and Fourier transform infrared (FTIR) spectroscopy, and electrochemical and viscosity measurement methods. Also, molecular docking studies were conducted at room temperature under physiological conditions (pH 7.4). The molecular docking studies showed that, in all cases, the lowest energy docking poses bind to the minor groove of DNA and the apigenin-DNA complex was stabilized by several hydrogen bonds. Also, π-sulfur interactions played a role in the stabilization of the ADSAM-DNA and ATSAM-DNA complexes. The binding affinities of the lowest energy docking pose (schematic diagram of table of content (TOC)) of APG-DNA, ADSAM-DNA, and ATSAM-DNA complexes were found to be -8.2, -8.5, and -8.4 kcal mol-1, respectively. The electrochemical binding constants K b were determined to be (1.05 × 105) ± 0.04, (0.47 × 105) ± 0.02, and (8.13 × 105) ± 0.03 for APG, ADSAM, and ATSAM, respectively (all of the tests were run in triplicate and expressed as the mean and standard deviation (SD)). The K b constants calculated for APG, ADSAM, and ATSAM are in harmony for all techniques. As a result of the incorporation of dimethylsulfamate groups into the APG structure, in the ADSAM-dsDNA and ATSAM-dsDNA complexes, in addition to hydrogen bonds, π-sulfur interactions have also contributed to the stabilization of the ligand-DNA complexes. This work provides new insights that could lead to the development of prospective drugs and vaccines.

Decreased drug resistance of bladder cancer using phytochemicals treatment

The aim of the study is to investigate the ability of phytochemicals to overcome the multiple drug resistance (MDR) of bladder cancer. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate the cytotoxic sensitivity of T24-GCB cells, a GCB resistant cell line, to different phytochemicals, including capsaicin, quercetin, curcumin, and resveratrol, and their combination with gemcitabine. Western blot analysis was used to detect the expression of membranous ABCC2 and metabolic proteins, DCK, TK1, and TK2 in tumor cells. Animal models were used to confirm the treatment efficacy of phytochemicals in combination with gemcitabine to bladder cancer. The observed/expected ratio of cytotoxicity analysis revealed that capsaicin has synergistic effect with gemcitabine to T24-GCB cells in a dose-dependent pattern. Quercetin, curcumin, and resveratrol have additive effect with gemcitabine to T24-GCB cells. Capsaicin and quercetin alone and combination with gemcitabine decreased the expression of ABCC2 and DCK and TKs, in T24-GCB cells. On the contrary, resveratrol and curcumin alone and combination with gemcitabine increased the expression of ABCC2 but decreased cytoplasmic kinases simultaneously. In xenografted subcutaneous tumor model on nude mice, combination treatment of capsaicin and gemcitabine demonstrated the highest tumor suppression effect when compared to capsaicin or gemcitabine treatment alone. The MDR of bladder cancer is closely related to membranous ABCC2, cytoplasmic DCK, and TKs expression. Capsaicin owns the strongest synergistic cytotoxic effect of gemcitabine to T24-GCB cells. This combination regimen may provide as an adjunctive treatment for overcoming MDR in bladder cancer.

p53-targeted lncRNA ST7-AS1 acts as a tumour suppressor by interacting with PTBP1 to suppress the Wnt/β-catenin signalling pathway in glioma

Glioma is the most prevalent intracranial tumour, with considerable morbidity. Long non-coding RNAs are important in the biological processes of various cancers. However, little is known about ST7 antisense RNA 1 (ST7-AS1) and its role in glioma progression. ST7-AS1 expression was reduced in glioma tissues and cells in comparison to normal brain tissues. p53 transcriptionally targeted the ST7-AS1 promoter in U251 glioma cells. The targeting significantly inhibited cell migration, invasion, and proliferation, and promoted apoptosis. ST7-AS1 directly bound to and downregulated polypyrimidine tract-binding protein 1 (PTBP1) at the post-transcriptional level. ST7-AS1 overexpression inhibited glioma progression by suppressing Wnt/β-catenin signalling by downregulating PTBP1 expression. Additionally, p53 expression negatively correlated with PTBP1 expression. Glioma progression is regulated by a positive feedback loop involving the p53/ST7-AS1/PTBP1 axis, which might be a promising therapeutic target for glioma treatment.

Flavonoids Targeting HIF-1: Implications on Cancer Metabolism

Tumor hypoxia is described as an oxygen deprivation in malignant tissue. The hypoxic condition is a consequence of an imbalance between rapidly proliferating cells and a vascularization that leads to lower oxygen levels in tumors. Hypoxia-inducible factor 1 (HIF-1) is an essential transcription factor contributing to the regulation of hypoxia-associated genes. Some of these genes modulate molecular cascades associated with the Warburg effect and its accompanying pathways and, therefore, represent promising targets for cancer treatment. Current progress in the development of therapeutic approaches brings several promising inhibitors of HIF-1. Flavonoids, widely occurring in various plants, exert a broad spectrum of beneficial effects on human health, and are potentially powerful therapeutic tools against cancer. Recent evidences identified numerous natural flavonoids and their derivatives as inhibitors of HIF-1, associated with the regulation of critical glycolytic components in cancer cells, including pyruvate kinase M2(PKM2), lactate dehydrogenase (LDHA), glucose transporters (GLUTs), hexokinase II (HKII), phosphofructokinase-1 (PFK-1), and pyruvate dehydrogenase kinase (PDK). Here, we discuss the results of most recent studies evaluating the impact of flavonoids on HIF-1 accompanied by the regulation of critical enzymes contributing to the Warburg phenotype. Besides, flavonoid effects on glucose metabolism via regulation of HIF-1 activity represent a promising avenue in cancer-related research. At the same time, only more-in depth investigations can further elucidate the mechanistic and clinical connections between HIF-1 and cancer metabolism.

Rationalizing the therapeutic potential of apigenin against cancer

BACKGROUND

Despite the remarkable advances made in the diagnosis and treatment of cancer during the past couple of decades, it remains the second largest cause of mortality in the world, killing approximately 9.6 million people annually. The major challenges in the treatment of the advanced stage of this disease are the development of chemoresistance, severe adverse effects of the drugs, and high treatment cost. Therefore, the development of drugs that are safe, efficacious, and cost-effective remains a 'Holy Grail' in cancer research. However, the research over the past four decades shed light on the cancer-preventive and therapeutic potential of natural products and their underlying mechanism of action. Apigenin is one such compound, which is known to be safe and has significant potential in the prevention and therapy of this disease.

AIM

To assess the literature available on the potential of apigenin and its analogs in modulating the key molecular targets leading to the prevention and treatment of different types of cancer.

METHOD

A comprehensive literature search has been carried out on PubMed for obtaining information related to the sources and analogs, chemistry and biosynthesis, physicochemical properties, biological activities, bioavailability and toxicity of apigenin.

KEY FINDINGS

The literature search resulted in many in vitro, in vivo and a few cohort studies that evidenced the effectiveness of apigenin and its analogs in modulating important molecular targets and signaling pathways such as PI3K/AKT/mTOR, JAK/STAT, NF-κB, MAPK/ERK, Wnt/β-catenin, etc., which play a crucial role in the development and progression of cancer. In addition, apigenin was also shown to inhibit chemoresistance and radioresistance and make cancer cells sensitive to these agents. Reports have further revealed the safety of the compound and the adaptation of nanotechnological approaches for improving its bioavailability.

SIGNIFICANCE

Hence, the present review recapitulates the properties of apigenin and its pharmacological activities against different types of cancer, which warrant further investigation in clinical settings.

Inhibitory effect of bound polyphenol from foxtail millet bran on miR-149 methylation increases the chemosensitivity of human colorectal cancer HCT-8/Fu cells

Nature polyphenols widely present in plants and foods are promising candidates in cancer chemotherapy. Emerging evidence has shown that plant polyphenols regulate the expression of miRNAs to exert the anti-Multidrug resistance (MDR) activity, which partly attributes to their regulation on miRNAs methylation. Our previous study found that bound polyphenol from foxtail millet bran (BPIS) had potential as an anti-MDR agent for colorectal cancer (CRC), but its mechanism remains unclear. The present findings demonstrated that BPIS upregulated the expression of miR-149 by reducing the methylation of its CpG islands, which subsequently induced the cell cycle arrest in G2/M phase, resulting in enhancing the chemo-sensitivity of HCT-8/Fu cells. Mechanically, BPIS and its active components (FA and p-CA) reduced miR-149 methylation by inhibiting the expression levels of DNA methyltransferases, promoting a remarkable increase of miR-149 expression. Further, the increased miR-149 induced cell cycle arrest in G₂/M phase by inhibiting the expression of Akt, Cyclin B1 and CDK1, thus increasing the chemosensitivity of HCT-8/Fu cells. Additionally, a strong inducer of DNA de-methylation (5-aza-dc) treatment markedly increased the chemosensitivity of CRC through elevating miR-149 expression, which indicates the hypermethylation of miR-149 may be the key cause of drug resistance in CRC. The study indicates that the enhanced chemosensitivity of BPIS on CRC is mainly attributed to the increase of miR-149 expression induced by methylation inhibition.

Flavonoids against the Warburg phenotype-concepts of predictive, preventive and personalised medicine to cut the Gordian knot of cancer cell metabolism

The Warburg effect is characterised by increased glucose uptake and lactate secretion in cancer cells resulting from metabolic transformation in tumour tissue. The corresponding molecular pathways switch from oxidative phosphorylation to aerobic glycolysis, due to changes in glucose degradation mechanisms known as the 'Warburg reprogramming' of cancer cells. Key glycolytic enzymes, glucose transporters and transcription factors involved in the Warburg transformation are frequently dysregulated during carcinogenesis considered as promising diagnostic and prognostic markers as well as treatment targets. Flavonoids are molecules with pleiotropic activities. The metabolism-regulating anticancer effects of flavonoids are broadly demonstrated in preclinical studies. Flavonoids modulate key pathways involved in the Warburg phenotype including but not limited to PKM2, HK2, GLUT1 and HIF-1. The corresponding molecular mechanisms and clinical relevance of 'anti-Warburg' effects of flavonoids are discussed in this review article. The most prominent examples are provided for the potential application of targeted 'anti-Warburg' measures in cancer management. Individualised profiling and patient stratification are presented as powerful tools for implementing targeted 'anti-Warburg' measures in the context of predictive, preventive and personalised medicine.

Apigenin induces apoptosis and counteracts cisplatin-induced chemoresistance via Mcl-1 in ovarian cancer cells

Ovarian cancer (OC) is one of the prominent causes of mortality in female patients diagnosed with gynecologic malignancies. While it has previously been demonstrated that apigenin inhibits cell growth in colon and breast cancer cells, the effect of apigenin in OC cells is not fully understood. Therefore, the aim of the present study was to investigate the impact of apigenin on cell death and resistance to cisplatin in OC cells. It was found that apigenin inhibited proliferation, hindered cell cycle progression and promoted SKOV3 cell apoptosis. Moreover, these effects were also observed in cisplatin-resistant SKOV3/DDP cells. Furthermore, apigenin reduced the mitochondrial transmembrane potential, and elevated the ratios of cleaved caspase-3/caspase-3 and Bax/Bcl-2 in the two cell types. Reverse transcription-quantitative PCR and western blotting results demonstrated that apigenin significantly downregulated Mcl-1 at the transcriptional and translational levels in SKOV3 and SKOV3/DDP cells, which was responsible for its cytotoxic functions and chemosensitizing effects. Collectively, the present results identified the impact of apigenin on OC cell death and resistance to cisplatin, and the potential molecular mechanisms. However, additional studies are required to further elucidate the underlying mechanisms.

The ameliorating effects of anthocyanins on the cross-linked signaling pathways of cancer dysregulated metabolism

Cancer cells underlie the dysregulated metabolism of carbohydrate, lipid and protein and thereby, employ interconnected cross-linked signaling pathways to supply adequate energy for growth and related biosynthetic procedures. In the present study, a comprehensive review of cancer metabolism and anthocyanin's effect was conducted using the existing electronic databases, including Medline, PubMed, Scopus, and Web of Science, as well as related articles in the field. Such keywords as "cancer", and "cancer metabolism" in the title/abstract/keyword and all the "anthocyanins" in the whole text were used. Data were collected without time restriction until February 2020. The results indicated the involvement of several signaling pathways, including inflammatory PI3K/Akt/mTOR pathway, Bax/Bcl-2/caspases as apoptosis modulators, and NF-κB/Nrf2 as oxidative stress mediators in the cancer dysregulated metabolism. Compelling studies have shown that targeting these pathways, as critical hallmarks of cancer, plays a critical role in combating cancer dysregulated metabolism. The complexity of cancer metabolism signaling pathways, along with toxicity, high costs, and resistance to conventional drugs urge the need to investigate novel multi-target agents. Increasing evidence has introduced plant-derived secondary metabolites as hopeful anticancer candidates which target multiple dysregulated cross-linked pathways of cancer metabolism. Amongst these metabolites, anthocyanins have demonstrated positive anticancer effects by targeting inflammation, oxidative stress, and apoptotic signaling pathways. The current study revealed the cross-linked signaling pathways of cancer metabolism, as well as the promising pharmacological mechanisms of anthocyanins in targeting the aforementioned signaling mediators. To overcome the pharmacokinetic limitations of anthocyanins in cancer treatment, their interactions with gut microbiota and the need to develop related nano-formulations were also considered.

Modulation of dysregulated cancer metabolism by plant secondary metabolites: A mechanistic review

Several signaling pathways and basic metabolites are responsible for the control of metabolism in both normal and cancer cells. As emerging hallmarks of cancer metabolism, the abnormal activities of these pathways are of the most noticeable events in cancer. This altered metabolism expedites the survival and proliferation of cancer cells, which have attracted a substantial amount of interest in cancer metabolism. Nowadays, targeting metabolism and cross-linked signaling pathways in cancer has been a hot topic to investigate novel drugs against cancer. Despite the efficiency of conventional drugs in cancer therapy, their associated toxicity, resistance, and high-cost cause limitations in their application. Besides, considering the numerous signaling pathways cross-linked with cancer metabolism, discovery, and development of multi-targeted and safe natural compounds has been a high priority. Natural secondary metabolites have exhibited promising anticancer effects by targeting dysregulated signaling pathways linked to cancer metabolism. The present review reveals the metabolism and cross-linked dysregulated signaling pathways in cancer. The promising therapeutic targets in cancer, as well as the critical role of natural secondary metabolites for significant anticancer enhancements, have also been highlighted to find novel/potential therapeutic agents for cancer treatment.

Roles of PTBP1 in alternative splicing, glycolysis, and oncogensis

Polypyrimidine tract-binding protein 1 (PTBP1) plays an essential role in splicing and is expressed in almost all cell types in humans, unlike the other proteins of the PTBP family. PTBP1 mediates several cellular processes in certain types of cells, including the growth and differentiation of neuronal cells and activation of immune cells. Its function is regulated by various molecules, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and RNA-binding proteins. PTBP1 plays roles in various diseases, particularly in some cancers, including colorectal cancer, renal cell cancer, breast cancer, and glioma. In cancers, it acts mainly as a regulator of glycolysis, apoptosis, proliferation, tumorigenesis, invasion, and migration. The role of PTBP1 in cancer has become a popular research topic in recent years, and this research has contributed greatly to the formulation of a useful therapeutic strategy for cancer. In this review, we summarize recent findings related to PTBP1 and discuss how it regulates the development of cancer cells.

Olive Oil Effects on Colorectal Cancer

Colorectal cancer is the fourth cause of cancer-related death worldwide. A Mediterranean diet showed protective action against colorectal cancer due to the intake of different substances. Olive oil is a fundamental component of the Mediterranean diet. Olive oil is rich in high-value health compounds (such as monounsaturated free fatty acids, squalene, phytosterols, and phenols). Phenolic compounds exert favourable effects on free radicals, inflammation, gut microbiota, and carcinogenesis. The interaction between gut microbiota and olive oil consumption could modulate colonic microbial composition or activity, with a possible role in cancer prevention. Gut microbiota is able to degrade some substances found in olive oil, producing active metabolites with chemopreventive action. Further clinical research is needed to clarify the beneficial effects of olive oil and its components. A better knowledge of the compounds found in olive oil could lead to the development of nutritional supplements or chemotherapeutic agents with a potential in the prevention and treatment of colorectal cancer.

Flavonoids and Colorectal Cancer Prevention

Colorectal cancer (CRC) is the third most common cancer, but despite advances in treatment, it remains the second most common cause of cancer-related mortality. Prevention may, therefore, be a key strategy in reducing colorectal cancer deaths. Given reports of an inverse association between fruit and vegetable consumption with colorectal cancer risk, there has been significant interest in understanding the metabolism and bioactivity of flavonoids, which are highly abundant in fruits and vegetables and account for their pigmentation. In this review, we discuss host and microbiota-mediated metabolism of flavonoids and the potential mechanisms by which flavonoids can exert protective effects against colon tumorigenesis, including regulation of signaling pathways involved in apoptosis, cellular proliferation, and inflammation and modulation of the gut microbiome.

Novel drug candidates for treating esophageal carcinoma: A study on differentially expressed genes, using connectivity mapping and molecular docking

Patients with esophageal carcinoma (ESCA) have a poor prognosis and high mortality rate. Although standard therapies have had effect, there is an urgent requirement to develop novel options, as increasing drug tolerance has been identified in clinical practice. In the present study, differentially expressed genes (DEGs) of ESCA were identified in The Cancer Genome Atlas and Genotype-Tissue Expression databases. Functional and protein-protein interaction (PPI) analyses were performed. The Connectivity Map (CMAP) was selected to predict drugs for the treatment of ESCA, and their target genes were acquired from the Search Tool for Interactions of Chemicals (STITCH) by uploading the Simplified Molecular-Input Line-Entry System structure. Additionally, significant target genes and ESCA-associated hub genes were extracted using another PPI analysis, and the corresponding drugs were added to construct a network. Furthermore, the binding affinity between predicted drug candidates and ESCA-associated hub genes was calculated using molecular docking. Finally, 827 DEGs (|log₂ fold-change|≥2; q-value <0.05), which are principally involved in protein digestion and absorption (P<0.005), the plasminogen-activating cascade (P<0.01), as well as the ‘biological regulation’ of the Biological Process, ‘membrane’ of the Cellular Component and ‘protein binding’ of the Molecular Function categories, were obtained. Additionally, 11 hub genes were obtained from the PPI network (all degrees ≥30). Furthermore, the 15 first screen drugs were extracted from CMAP (score <−0.85) and the 9 second screen drugs with 70 target genes were extracted from STITCH. Furthermore, another PPI analysis extracted 51 genes, and apigenin, baclofen, Prestwick-685, menadione, butyl hydroxybenzoate, gliclazide and valproate were selected as drug candidates for ESCA. Those molecular docking results with a docking score of >5.52 indicated the significance of apigenin, Prestwick-685 and menadione. The results of the present study may lead to novel drug candidates for ESCA, among which Prestwick-685 and menadione were identified to be significant new drug candidates.