Concomitant inhibition of HSP90, its mitochondrial localized homologue TRAP1 and HSP27 by green tea in pancreatic cancer HPAF-II cells

Herbals and Plants in the Treatment of Pancreatic Cancer: A Systematic Review of Experimental and Clinical Studies

Background: Pancreatic cancer represents the most lethal malignancy among all digestive cancers. Despite the therapeutic advances achieved during recent years, the prognosis of this neoplasm remains disappointing. An enormous amount of experimental (mainly) and clinical research has recently emerged referring to the effectiveness of various plants administered either alone or in combination with chemotherapeutic agents. Apart from Asian countries, the use of these plants and herbals in the treatment of digestive cancer is also increasing in a number of Western countries as well. The aim of this study is to review the available literature regarding the efficacy of plants and herbals in pancreatic cancer. Methods: The authors have reviewed all the experimental and clinical studies published in Medline and Embase, up to June 2021. Results: More than 100 plants and herbals were thoroughly investigated. Favorable effects concerning the inhibition of cancer cell lines in the experimental studies and a favorable clinical outcome after combining various plants with established chemotherapeutic agents were observed. These herbals and plants exerted their activity against pancreatic cancer via a number of mechanisms. The number and severity of side-effects are generally of a mild degree. Conclusion: A quite high number of clinical and experimental studies confirmed the beneficial effect of many plants and herbals in pancreatic cancer. More large, double-blind clinical studies assessing these natural products, either alone or in combination with chemotherapeutic agents should be conducted.

Polyphenols as Possible Agents for Pancreatic Diseases

Pancreatic cancer (PC) is very aggressive and it is estimated that it kills nearly 50% of patients within the first six months. The lack of symptoms specific to this disease prevents early diagnosis and treatment. Today, gemcitabine alone or in combination with other cytostatic agents such as cisplatin (Cis), 5-fluorouracil (5-FU), irinotecan, capecitabine, or oxaliplatin (Oxa) is used in conventional therapy. Outgoing literature provides data on the use of polyphenols, biologically active compounds, in the treatment of pancreatic cancer and the prevention of acute pancreatitis. Therefore, the first part of this review gives a brief overview of the state of pancreatic disease as well as the procedures for its treatment. The second part provides a detailed overview of the research regarding the anticancer effects of both pure polyphenols and their plant extracts. The results regarding the antiproliferative, antimetastatic, as well as inhibitory effects of polyphenols against PC cell lines as well as the prevention of acute pancreatitis are presented in detail. Finally, particular emphasis is given to the polyphenolic profiles of apples, berries, cherries, sour cherries, and grapes, given the fact that these fruits are rich in polyphenols and anthocyanins. Polyphenolic profiles, the content of individual polyphenols, and their relationships are discussed. Based on this, significant data can be obtained regarding the amount of fruit that should be consumed daily to achieve a therapeutic effect.

New insights into molecular chaperone TRAP1 as a feasible target for future cancer treatments

Tumor necrosis factor receptor-associated protein 1 (TRAP1), a molecular chaperone, is a major member of the mitochondrial heat shock protein 90 (Hsp90) family. Studies have shown that TRAP1 can prevent hypoxia-induced damage to cardiomyocytes, maintain cardiomyocytes viability and mitochondrial membrane potential, and protect cardiomyocytes. In addition, it can also protect astrocytes from ischemic damage in vitro. In recent years, there have been many new discoveries in tumors. The abnormal expression of TRAP1 is closely related to the occurrence and development of various tumors. TRAP1 protein seems to be a central regulatory protein, involved in the activation of various oncogenic proteins and signaling pathways, and has a balanced function at tumor transformation and the intersection of different metabolic processes. Targeting its chaperone activity and molecular interactions can destroy the metabolism and survival adaptability of tumor cells, paving the way for the development of highly selective mitochondrial anti-tumor drugs. Moreover, the combination of TRAP1 inhibition and current traditional cancer therapies has shown promising applications. These findings have important implications for the diagnosis and treatment of tumors. Therefore, we reviewed the recently identified functions of the molecular chaperone TRAP1 in cancer development and progression, as well as the discovery and recent advances in selective TRAP1 inhibitors as anticancer drug therapies, opening up new attractive prospects for exploring strategies for targeting TRAP1 as a tumor cell target.

Natural Products and Derivatives Targeting at Cancer Energy Metabolism: A Potential Treatment Strategy

In the 1920s, Dr Otto Warburg first suggested the significant difference in energy metabolism between malignant cancer cells and adjacent normal cells. Tumor cells mainly adopt the glycolysis as energy source to maintain tumor cell growth and biosynthesis under aerobic conditions. Investigation on energy metabolism pathway in cancer cells has aroused the interest of cancer researchers all around the world. In recent years, plentiful studies suggest that targeting the peculiar cancer energy metabolic pathways, including glycolysis, mitochondrial respiration, amino acid metabolism, and fatty acid oxidation may be an effective strategy to starve cancer cells by blocking essential nutrients. Natural products (NPs) are considered as the "treasure trove of small molecules drugs" and have played an extremely remarkable role in the discovery and development of anticancer drugs. And numerous NPs have been reported to act on cancer energy metabolism targets. Herein, a comprehensive overview about cancer energy metabolism targets and their natural-occurring inhibitors is prepared.

Anti-cancer effects of polyphenols via targeting p53 signaling pathway: updates and future directions

The anticancer effects of polyphenols are ascribed to several signaling pathways including the tumor suppressor gene tumor protein 53 (p53). Expression of endogenous p53 is silent in various types of cancers. A number of polyphenols from a wide variety of dietary sources could upregulate p53 expression in several cancer cell lines through distinct mechanisms of action. The aim of this review is to focus the significance of p53 signaling pathways and to provide molecular intuitions of dietary polyphenols in chemoprevention by monitoring p53 expression that have a prominent role in tumor suppression.

NRF2 transcriptionally activates the heat shock factor 1 promoter under oxidative stress and affects survival and migration potential of MCF7 cells

Functional up-regulation of heat shock factor 1 (HSF1) activity through different posttranslational modifications has been implicated in the survival and proliferation of various cancers. It is increasingly recognized that the HSF1 gene is also up-regulated at the transcriptional level, a phenomenon correlated with poor prognosis for patients with different cancers, including breast cancer. Here, we analyzed the transcriptional up-regulation of HSF1 in human cells upon arsenite- or peroxide-induced oxidative stress. Sequential promoter truncation coupled with bioinformatics analysis revealed that this activation is mediated by two antioxidant response elements (AREs) located between 1707 and 1530 bp upstream of the transcription start site of the HSF1 gene. Using shRNA-mediated down-regulation, ChIP of NRF2, site-directed mutagenesis of the AREs, and DNase I footprinting of the HSF1 promoter, we confirmed that nuclear factor erythroid-derived 2-like 2 (NRF2, also known as NFE2L2) interacts with these AREs and up-regulates HSF1 expression. We also found that BRM/SWI2-related gene 1 (BRG1), a catalytic subunit of SWI2/SNF2-like chromatin remodeler, is involved in this process. We further show that NRF2-dependent HSF1 gene regulation plays a crucial role in cancer cell biology, as interference with NRF2-mediated HSF1 activation compromised survival, migration potential, and the epithelial-to-mesenchymal transition and autophagy in MCF7 breast cancer cells exposed to oxidative stress. Taken together, our findings unravel the mechanistic basis of HSF1 gene regulation in cancer cells and provide molecular evidence supporting a direct interaction between HSF1 and NRF2, critical regulators of two cytoprotective mechanisms exploited by cancer cells.

Anticancer Effects of Green Tea and the Underlying Molecular Mechanisms in Bladder Cancer

Green tea and green tea polyphenols (GTPs) are reported to inhibit carcinogenesis and malignant behavior in several diseases. Various in vivo and in vitro studies have shown that GTPs suppress the incidence and development of bladder cancer. However, at present, opinions concerning the anticancer effects and preventive role of green tea are conflicting. In addition, the detailed molecular mechanisms underlying the anticancer effects of green tea in bladder cancer remain unclear, as these effects are regulated by several cancer-related factors. A detailed understanding of the pathological roles and regulatory mechanisms at the molecular level is necessary for advancing treatment strategies based on green tea consumption for patients with bladder cancer. In this review, we discuss the anticancer effects of GTPs on the basis of data presented in in vitro studies in bladder cancer cell lines and in vivo studies using animal models, as well as new treatment strategies for patients with bladder cancer, based on green tea consumption. Finally, on the basis of the accumulated data and the main findings, we discuss the potential usefulness of green tea as an antibladder cancer agent and the future direction of green tea-based treatment strategies for these patients.

Past, present, and emerging roles of mitochondrial heat shock protein TRAP1 in the metabolism and regulation of cancer stem cells

Tumor necrosis factor receptor-associated protein 1 (TRAP1), a member of the HSP90 family, controls a variety of physiological functions, including cell proliferation, differentiation, and survival. Most studies have been devoted to understanding the anti-apoptotic roles of TRAP1 in cancer and targeting it for tumor control in clinical settings. Additionally, we have identified a new role for TRAP1 in regulation of liver regeneration after partial hepatectomy in TRAP1 transgenic mice and cellular proliferation in TRAP1-overexpressing cells, via mitochondrial alterations. Moreover, recent works have indicated a role for TRAP1 in the regulation of cancer stem cells (CSCs) as well as a metabolic switch between mitochondrial respiration and aerobic glycolysis called as "Warburg effect." This review discusses the implications of TRAP1 action for both metabolism and the regulation of CSCs.

Plant natural products: from traditional compounds to new emerging drugs in cancer therapy

Natural products are chemical compounds or substances produced naturally by living organisms. With the development of modern technology, more and more plant extracts have been found to be useful to medical practice. Both micromolecules and macromolecules have been reported to have the ability to inhibit tumour progression, a novel weapon to fight cancer by targeting its 10 characteristic hallmarks. In this review, we focus on summarizing plant natural compounds and their derivatives with anti-tumour properties, into categories, according to their potential therapeutic strategies against different types of human cancer. Taken together, we present a well-grounded review of these properties, hoping to shed new light on discovery of novel anti-tumour therapeutic drugs from known plant natural sources.

Metabolic Consequences of LDHA inhibition by Epigallocatechin Gallate and Oxamate in MIA PaCa-2 Pancreatic Cancer Cells

Lactate dehydrogenase A (LDHA) is the enzyme that converts pyruvate to lactate and oxidizes the reduced form of nicotinamide adenine dinucleotide (NADH) to NAD⁺. Several human cancers including the pancreas display elevated expression of LDHA. Because of its essential role in cancer metabolism, LDHA has been considered to be a potential target for cancer therapy. Recently, we have shown that a green tea extract significantly down-regulated LDHA in HPAF-II pancreatic cancer cells using global proteomics profiling. The present study is to investigate how EGCG, a major biological active constituent of green tea, targets the metabolism of human pancreatic adenocarcinoma MIA PaCa-2 cells. We compared the effect of EGCG to that of oxamate, an inhibitor of LDHA, on the multiple metabolic pathways as measured by extracellular lactate production, glucose consumption, as well as intracellular aspartate and glutamate production, fatty acid synthesis, acetyl-CoA, RNA ribose and deoxyribose. Specific metabolic pathways were studied using [1, 2-¹³C₂]-d-glucose as the single precursor metabolic tracer. Isotope incorporations in metabolites were analyzed using gas chromatography/mass spectrometry (GC/MS) and stable isotope-based dynamic metabolic profiling (SiDMAP). We found that the EGCG treatment of MIA PaCa-2 cells significantly reduced lactate production, anaerobic glycolysis, glucose consumption and glycolytic rate that are comparable to the inhibition of LDHA by oxamate treatment. Significant changes in intracellular glucose carbon re-distribution among major glucose-utilizing macromolecule biosynthesis pathways in response to EGCG and oxamate treatment were observed. The inhibition of LDHA by EGCG or oxamate impacts on various pathways of the cellular metabolic network and significantly modifies the cancer metabolic phenotype. These results suggest that phytochemical EGCG and LDHA inhibitor oxamate confer their anti-cancer activities by disrupting the balance of flux throughout the cellular metabolic network.

Green tea consumption and risk of pancreatic cancer: a meta-analysis

Emerging laboratory and animal studies indicate that green tea inhibits development and progression of pancreatic cancer, but evidence from epidemiologic studies appears inconsistent and inconclusive. A meta-analysis summarizing published case-control and cohort studies was performed to evaluate the association of green tea consumption with risk of pancreatic cancer. Pertinent studies were identified by a search of PubMed and EMBASE up to April 2014. A random-effects model was assigned to compute summary risk estimates. A total of three case-control studies and five prospective studies were included, comprising 2317 incident cases and 288209 subjects. Of them, three studies were from China and the reminders were conducted in Japan. Overall, neither high vs. low green consumption (odds ratio (OR) = 0.99, 95% confidence interval [CI] = 0.78–1.25), nor an increase in green tea consumption of two cups/day (OR = 0.95, 95% CI = 0.85–1.06) was associated with risk of pancreatic cancer. The null association persisted when the analysis was stratified by sex or restricted to non-smokers. In the stratification by study location, the summary OR for the studies from China and for those from Japan was 0.77 (95% CI = 0.60–0.99) and 1.21 (95% CI = 0.94–1.54), respectively (P for differences = 0.04). Cumulative epidemiologic evidence suggests that green tea consumption is not associated with pancreatic cancer.

Investigating flavonoids as molecular templates for the design of small-molecule inhibitors of cell signaling

Epidemiological and clinical trials reveal compelling evidence for the ability of dietary flavonoids to lower cardiovascular disease risk. The mechanisms of action of these polyphenolic compounds are diverse, and of particular interest is their ability to function as protein and lipid kinase inhibitors. We have previously described structure-activity studies that reinforce the possibility for using flavonoid structures as templates for drug design. In the present study, we aim to begin constructing rational screening strategies for exploiting these compounds as templates for the design of clinically relevant, antiplatelet agents. We used the platelet as a model system to dissect the structural influence of flavonoids, stilbenes, anthocyanidins, and phenolic acids on inhibition of cell signaling and function. Functional groups identified as relevant for potent inhibition of platelet function included at least 2 benzene rings, a hydroxylated B ring, a planar C ring, a C ring ketone group, and a C-2 positioned B ring. Hydroxylation of the B ring with either a catechol group or a single C-4' hydroxyl may be required for efficient inhibition of collagen-stimulated tyrosine phosphorylated proteins of 125 to 130 kDa, but may not be necessary for that of phosphotyrosine proteins at approximately 29 kDa. The removal of the C ring C-3 hydroxyl together with a hydroxylated B ring (apigenin) may confer selectivity for 37 to 38 kDa phosphotyrosine proteins. We conclude that this study may form the basis for construction of maps of flavonoid inhibitory activity on kinase targets that may allow a multitargeted therapeutic approach with analogue counterparts and parent compounds.

TRAP1 revisited: novel localizations and functions of a 'next-generation' biomarker (review)

In the last decade, the identification and characterization of novel molecular mechanisms and pathways involving the heat shock protein TRAP1/HSP75 in cancers and other diseases enhanced the scientific interest. Recent reports have shown that TRAP1 stays at the crossroad of multiple crucial processes in the onset of neoplastic transformation. In fact, TRAP1: i) contributes to the tumor's switch to aerobic glycolysis through the inhibition of succinate dehydrogenase, the complex II of the mitochondrial respiratory chain; ii) is part of a pro-survival signaling pathway aimed at evading the toxic effects of oxidants and anticancer drugs and protects mitochondria against damaging stimuli via a decrease of ROS generation; iii) controls protein homeostasis through a direct involvement in the regulation of protein synthesis and protein co-translational degradation. Therefore, TRAP1 seems to be a central regulatory protein with balancing functions at the intersection of different metabolic processes during the neoplastic transformation. For this reason, it can be considered at the same time an attractive target for the development of novel anticancer strategies and a promising study model to understand the biology of tumor cells at a systemic level. This review summarizes the most recent advances in TRAP1 biology and proposes a new comprehensive view of its functions.

Modulation of colonic inflammation in Mdr1a(-/-) mice by green tea polyphenols and their effects on the colon transcriptome and proteome

Animal models are an important tool to understand the complex pathogenesis of inflammatory bowel diseases (IBDs). This study tested the anti-inflammatory potential of a green tea extract rich in polyphenols (GrTP) in the colon of the multidrug resistance targeted mutation (Mdr1a(-/-)) mouse model of IBD. Insights into mechanisms responsible for this reduction in inflammation were gained using transcriptome and proteome analyses. Mice were randomly assigned to an AIN-76A (control) or GrTP-enriched diet. At 21 or 24 weeks of age, a colonic histological injury score was determined for each mouse, colon mRNA transcript levels were assessed using microarrays, and colon protein expression was measured using two-dimensional gel electrophoresis and liquid chromatography-mass spectrometry protein identification. Mean colonic histological injury score of GrTP-fed Mdr1a(-/-) mice was significantly lower compared to those fed the control diet. Microarray and proteomics analyses showed reduced abundance of transcripts and proteins associated with immune and inflammatory response and fibrinogenesis pathways, and increased abundance of those associated with xenobiotic metabolism pathways in response to GrTP, suggesting that its anti-inflammatory activity is mediated by multiple molecular pathways. Peroxisome proliferator-activated receptor-α and signal transducer and activator of transcription 1 appear to be two key molecules which regulate these effects. These results support the view that dietary intake of polyphenols derived from green tea can ameliorate intestinal inflammation in the colon of a mouse model of IBD, and are in agreement with studies suggesting that consumption of green tea may reduce IBD symptoms and therefore play a part in an overall IBD treatment regimen.

Advancements in the analysis of the Arabidopsis plasma membrane proteome

The plasma membrane (PM) regulates diverse processes essential to plant growth, development, and survival in an ever-changing environment. In addition to maintaining normal cellular homeostasis and plant nutrient status, PM proteins perceive and respond to a myriad of environmental cues. Here we review recent advances in the analysis of the plant PM proteome with a focus on the model plant Arabidopsis thaliana. Due to membrane heterogeneity, hydrophobicity, and low relative abundance, analysis of the PM proteome has been a special challenge. Various experimental techniques to enrich PM proteins and different protein and peptide separation strategies have facilitated the identification of thousands of integral and membrane-associated proteins. Numerous classes of proteins are present at the PM with diverse biological functions. PM microdomains have attracted much attention. However, it still remains a challenge to characterize these cell membrane compartments. Dynamic changes in the PM proteome in response to different biotic and abiotic stimuli are highlighted. Future prospects for PM proteomics research are also discussed.

Developmental distribution of the plasma membrane-enriched proteome in the maize primary root growth zone

Within the growth zone of the maize primary root, there are well-defined patterns of spatial and temporal organization of cell division and elongation. However, the processes underlying this organization remain poorly understood. To gain additional insights into the differences amongst the defined regions, we performed a proteomic analysis focusing on fractions enriched for plasma membrane (PM) proteins. The PM is the interface between the plant cell and the apoplast and/or extracellular space. As such, it is a key structure involved in the exchange of nutrients and other molecules as well as in the integration of signals that regulate growth and development. Despite the important functions of PM-localized proteins in mediating these processes, a full understanding of dynamic changes in PM proteomes is often impeded by low relative concentrations relative to total proteins. Using a relatively simple strategy of treating microsomal fractions with Brij-58 detergent to enrich for PM proteins, we compared the developmental distribution of proteins within the root growth zone which revealed a number of previously known as well as novel proteins with interesting patterns of abundance. For instance, the quantitative proteomic analysis detected a gradient of PM aquaporin proteins similar to that previously reported using immunoblot analyses, confirming the veracity of this strategy. Cellulose synthases increased in abundance with increasing distance from the root apex, consistent with expected locations of cell wall deposition. The similar distribution pattern for Brittle-stalk-2-like protein implicates that this protein may also have cell wall related functions. These results show that the simplified PM enrichment method previously demonstrated in Arabidopsis can be successfully applied to completely unrelated plant tissues and provide insights into differences in the PM proteome throughout growth and development zones of the maize primary root.

Pancreatic cancer chemoprevention by phytochemicals

Pancreatic cancer is fourth leading cause of cancer-related deaths in the United States of America. In spite of recent advances in the current therapeutic modalities such as surgery, radiation and chemotherapy patients, the average five year survival rate remains still less than 5%. Recently, compounds from natural sources receive ample of attention as anti-cancer agents. Many epidemiological studies published over the past few decades provide a strong correlation between consumption of vegetables, fruits or plant derived products and reduced incidence of cancer. The present review focuses on the potential antitumor effects of various natural products.

Heat shock proteins and heat shock factor 1 in carcinogenesis and tumor development: an update

Heat shock proteins (HSP) are a subset of the molecular chaperones, best known for their rapid and abundant induction by stress. HSP genes are activated at the transcriptional level by heat shock transcription factor 1 (HSF1). During the progression of many types of cancer, this heat shock transcriptional regulon becomes co-opted by mechanisms that are currently unclear, although evidently triggered in the emerging tumor cell. Concerted activation of HSF1 and the accumulation of HSPs then participate in many of the traits that permit the malignant phenotype. Thus, cancers of many histologies exhibit activated HSF1 and increased HSP levels that may help to deter tumor suppression and evade therapy in the clinic. We review here the extensive work that has been carried out and is still in progress aimed at (1) understanding the oncogenic mechanisms by which HSP genes are switched on, (2) determining the roles of HSF1/HSP in malignant transformation and (3) discovering approaches to therapy based on disrupting the influence of the HSF1-controlled transcriptome in cancer.