Green tea polyphenol epigallocatechin-3-gallate (EGCG) as adjuvant in cancer therapy

Improved Stability and Targeted Cytotoxicity of Epigallocatechin-3-Gallate Palmitate for Anticancer Therapy

Although with high antioxidant activity, epigallocatechin-3-gallate (EGCG) was restricted by its poor chemical stability in practical applications. One of EGCG derivatives, EGCG palmitate, was synthesized with EGCG and palmitoyl chloride to overcome instability of EGCG. However, uncertainties still exist in chemical stability and cytotoxicity of EGCG palmitate, which are essential for further exploration in anticancer therapy. Our work aims to analyze the resistance of EGCG palmitate to oxidation and summarize its targeted inhibition efficiency on cancerous cells and normal cells. High-performance liquid chromatography analysis confirmed that EGCG palmitate remained stable in air and Dulbecco's modified eagle medium (DMEM) for a longer time than EGCG. Antioxidative and pro-oxidative effects of EGCG palmitate on treated cells are proposed through reactive oxygen species (ROS) detection, respectively. It reveals that pro-oxidants by H₂O₂ production can exert antiproliferative and proapoptotic effects on cancerous cells and stimulate autophagy, while an antioxidant relieves oxidative stress caused by superoxide as compared to normal cells. Consequently, targeted cytotoxicity is adopted by EGCG palmitate-treated cancerous cells. Results above manifest that EGCG palmitate possesses potential to serve as a promising prodrug in anticancer treatment.

Comprehensive Review of Methodology to Detect Reactive Oxygen Species (ROS) in Mammalian Species and Establish Its Relationship with Antioxidants and Cancer

Evidence suggests that reactive oxygen species (ROS) mediate tissue homeostasis, cellular signaling, differentiation, and survival. ROS and antioxidants exert both beneficial and harmful effects on cancer. ROS at different concentrations exhibit different functions. This creates necessity to understand the relation between ROS, antioxidants, and cancer, and methods for detection of ROS. This review highlights various sources and types of ROS, their tumorigenic and tumor prevention effects; types of antioxidants, their tumorigenic and tumor prevention effects; and abnormal ROS detoxification in cancer; and methods to measure ROS. We conclude that improving genetic screening methods and bringing higher clarity in determination of enzymatic pathways and scale-up in cancer models profiling, using omics technology, would support in-depth understanding of antioxidant pathways and ROS complexities. Although numerous methods for ROS detection are developing very rapidly, yet further modifications are required to minimize the limitations associated with currently available methods.

Effect of antioxidants coenzyme Q10 and β-carotene on the cytotoxicity of vemurafenib against human malignant melanoma

Melanoma is a type of highly invasive skin cancer derived from melanocytes with poor prognosis. Vemurafenib (PLX4032) is a clinically approved targeted therapeutic for BRAF mutant melanoma that has a high therapeutic response rate and significantly prolongs the overall survival time of patients with melanoma. Antioxidants have been widely used as supplements for cancer prevention and for decreasing the side effects of cancer therapy. However, antioxidants can also protect cancer cells from oxidative stress and promote cancer growth and progression. The present study aimed to examine the effect of the antioxidants coenzyme Q10 (CoQ10) and β-carotene on melanoma cell growth and invasiveness and on the cytotoxicity of vemurafenib against both vemurafenib-sensitive (SK-MEL-28) and vemurafenib-resistant (A2058) human malignant melanoma cell lines. MTS assay and wound-healing assay demonstrated that CoQ10 alone significantly reduced the viability and migration of melanoma cells, respectively, and synergistically worked with vemurafenib to decrease the viability and migration of human melanoma cells. In contrast, MTS assay and flow cytometry revealed that β-carotene alone did not affect the viability and apoptosis induction of melanoma cells; however, it inhibited cell migration and invasiveness. Wound-healing and Transwell assay demonstrated that β-carotene alleviated the cytotoxicity of vemurafenib and mitigated the inhibitory effect of vemurafenib on cell migration and invasion. Both CoQ10 and β-carotene protected melanoma cells from undergoing apoptosis induced by vemurafenib. Immunoblotting demonstrated that β-carotene at physiological concentration worked synergistically with vemurafenib to suppress the Ras-Raf-Mek-Erk intracellular signaling pathway. The present study aimed to add to the evidence of the in vitro effects of CoQ10 and β-carotene on the antimelanoma effects of vemurafenib.

Iron-crosslinked Rososome with robust stability and high drug loading for synergistic cancer therapy

Development of liposomal nanomedicine with robust stability, high drug loading and synergistic efficacy is a promising strategy for effective cancer therapy. Here, we present an iron-crosslinked rosmarinic liposome (Rososome) which can load high contents of drugs (including 25.8% rosmarinic acid and 9.04% doxorubicin), keep stable in a high concentration of anionic detergent and exhibit synergistic anti-cancer efficacy. The Rososomes were constructed by rosmarinic acid-lipid conjugates which not only work synergistically with doxorubicin by producing reactive oxygen species but also provide catechol moieties for the iron cross-linkages. The cross-linkages can lock the payloads tightly, endowing the crosslinked Rososome with better stability and pharmacokinetics than its non-crosslinked counterpart. On the syngeneic mouse model of breast cancer, the iron-crosslinked Rososomes exhibit better anticancer efficacy than free rosmarinic acid, doxorubicin, non-crosslinked Rososome and commercial liposomal formulation of doxorubicin (DOXIL). This study introduces a novel strategy for the development of liposomes with robust stability, high drug loading and synergistic anti-cancer efficacy.

DYRK1A: a down syndrome-related dual protein kinase with a versatile role in tumorigenesis

Dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) is a dual kinase that can phosphorylate its own activation loop on tyrosine residue and phosphorylate its substrates on threonine and serine residues. It is the most studied member of DYRK kinases, because its gene maps to human chromosome 21 within the Down syndrome critical region (DSCR). DYRK1A overexpression was found to be responsible for the phenotypic features observed in Down syndrome such as mental retardation, early onset neurodegenerative, and developmental heart defects. Besides its dual activity in phosphorylation, DYRK1A carries the characteristic of duality in tumorigenesis. Many studies indicate its possible role as a tumor suppressor gene; however, others prove its pro-oncogenic activity. In this review, we will focus on its multifaceted role in tumorigenesis by explaining its participation in some cancer hallmarks pathways such as proliferative signaling, transcription, stress, DNA damage repair, apoptosis, and angiogenesis, and finally, we will discuss targeting DYRK1A as a potential strategy for management of cancer and neurodegenerative disorders.

Nutraceuticals and Exercise against Muscle Wasting during Cancer Cachexia

Cancer cachexia (CC) is a debilitating multifactorial syndrome, involving progressive deterioration and functional impairment of skeletal muscles. It affects about 80% of patients with advanced cancer and causes premature death. No causal therapy is available against CC. In the last few decades, our understanding of the mechanisms contributing to muscle wasting during cancer has markedly increased. Both inflammation and oxidative stress (OS) alter anabolic and catabolic signaling pathways mostly culminating with muscle depletion. Several preclinical studies have emphasized the beneficial roles of several classes of nutraceuticals and modes of physical exercise, but their efficacy in CC patients remains scant. The route of nutraceutical administration is critical to increase its bioavailability and achieve the desired anti-cachexia effects. Accumulating evidence suggests that a single therapy may not be enough, and a bimodal intervention (nutraceuticals plus exercise) may be a more effective treatment for CC. This review focuses on the current state of the field on the role of inflammation and OS in the pathogenesis of muscle atrophy during CC, and how nutraceuticals and physical activity may act synergistically to limit muscle wasting and dysfunction.

The epigallocatechin gallate derivative Y6 reduces the cardiotoxicity and enhances the efficacy of daunorubicin against human hepatocellular carcinoma by inhibiting carbonyl reductase 1 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Green tea is the most ancient and popular beverage worldwide and its main constituent epigallocatechin-3-gallate (EGCG) has a potential role in the management of cancer through the modulation of cell signaling pathways. However, EGCG is frangible to oxidation and exhibits low lipid solubility and bioavailability, and we synthesized a derivative of EGCG in an attempt to overcome these limitations.

AIM OF THE STUDY

The anthracycline antibiotic daunorubicin (DNR) is a potent anticancer agent. However, its severe cardiotoxic limits its clinical efficacy. Human carbonyl reductase 1 (CBR1) is one of the most effective human reductases for producing hydroxyl metabolites and thus may be involved in increasing the cardiotoxicity and decreasing the antineoplastic effect of anthracycline antibiotics. Accordingly, in this study, we investigated the co-therapeutic effect of Y6, a novel and potent adjuvant obtained by optimization of the structure of EGCG.

MATERIAL AND METHODS

The cellular concentrations of DNR and its metabolite DNRol were measured by HPLC to determine the effects of EGCG and Y6 on the inhibition of DNRol formation. The cytotoxic effects of EGCG and Y6 were tested by MTT assay in order to identify non-toxic concentrations of them. To understand their antitumor and cardioprotective mechanisms, hypoxia-inducible factor-1α (HIF-1α) and CBR1 protein expression was measured via Western blotting and immunohistochemical staining while gene expression was analyzed using RT-PCR. Moreover, PI3K/AKT and MEK/ERK signaling pathways were analyzed via Western blotting. HepG2 xenograft model was used to detect the effects of EGCG and Y6 on the antitumor activity and cardiotoxicity of DNR in vivo. Finally, to obtain further insight into the interactions of Y6 and EGCG with HIF-1α and CBR1, we performed a molecular modeling.

RESULTS

Y6(10 μg/ml or 55 mg/kg) decreased the expression of HIF-1α and CBR1 at both the mRNA and protein levels during combined drug therapy in vitro as well as in vivo, thereby inhibiting formation of the metabolite DNRol from DNR, with the mechanisms being related to PI3K/AKT and MEK/ERK signaling inhibition. In a human carcinoma xenograft model established with subcutaneous HepG2 cells, Y6(55 mg/kg) enhanced the antitumor effect and reduced the cardiotoxicity of DNR more effectively than EGCG(40 mg/kg).

CONCLUSIONS

Y6 has the ability to inhibit CBR1 expression through the coordinate inhibition of PI3K/AKT and MEK/ERK signaling, then synergistically enhances the antitumor effect and reduces the cardiotoxicity of DNR.

Assessment Synergistic Effects of Integrated Therapy with Epigallocatechin-3-Gallate (EGCG) & Arsenic Trioxide and Irradiation on Breast Cancer Cell Line

Background:

Breast cancer is the most common invasive malignancy among women in the world. The current breast cancer therapies pose significant clinical challenges. Low-dose chemotherapy represents a new strategy to treat solid tumors in combination with natural products such as green tea catechins. Epigallocatechin-3-gallate (EGCG) is the major polyphenolic extract from green tea with potent anticancer and antioxidant effects. The purpose of this study was to investigate the effects of EGCG, Arsenic trioxide (ATO) and gamma radiation on MCF-7 cell line.

Methods:

The anti-proliferative effects of EGCG and ATO individually, moreover in combination with radiation on MCF-7 cells were evaluated with MTT assay. The expression of apoptotic gens (Bax, Bcl-2, Caspase-3 and Fas) was assessed by real-time PCR.

Results:

Based on the results of MTT assay, EGCG and ATO exhibited dose and time-dependent anti-proliferative effects on MCF-7 cells. The combined therapy of EGCG and ATO in presence and absence radiation could rise cell death up to 80%. Moreover, integrated therapy made Bax up-regulated and Bcl-2 down- regulated.

Conclusion:

In assessment synergistic effects of integrated therapy with EGCG and ATO and irradiation had been significant impact on low dose chemotherapy for breast cancer treatment.

Green tea polyphenolic antioxidants oxidize hydrogen sulfide to thiosulfate and polysulfides: A possible new mechanism underpinning their biological action

Matcha and green tea catechins such as (−)-epicatechin (EC), (−)-epigallocatechin (EGC) and (−)-epigallocatechin gallate (EGCG) have long been studied for their antioxidant and health-promoting effects. Using specific fluorophores for H₂S (AzMC) and polysulfides (SSP4) as well as IC-MS and UPLC-MS/MS-based techniques we here show that popular Japanese and Chinese green teas and select catechins all catalytically oxidize hydrogen sulfide (H₂S) to polysulfides with the potency of EGC > EGCG >> EG. This reaction is accompanied by the formation of sulfite, thiosulfate and sulfate, consumes oxygen and is partially inhibited by the superoxide scavenger, tempol, and superoxide dismutase but not mannitol, trolox, DMPO, or the iron chelator, desferrioxamine. We propose that the reaction proceeds via a one-electron autoxidation process during which one of the OH-groups of the catechin B-ring is autooxidized to a semiquinone radical and oxygen is reduced to superoxide, either of which can then oxidize HS⁻ to thiyl radicals (HS^•) which react to form hydrogen persulfide (H₂S₂). H₂S oxidation reduces the B-ring back to the hydroquinone for recycling while the superoxide is reduced to hydrogen peroxide (H₂O₂). Matcha and catechins also concentration-dependently and rapidly produce polysulfides in HEK293 cells with the potency order EGCG > EGC > EG, an EGCG threshold of ~300 nM, and an EC₅₀ of ~3 μM, suggesting green tea also acts as powerful pro-oxidant in vivo. The resultant polysulfides formed are not only potent antioxidants, but elicit a cascade of secondary cytoprotective effects, and we propose that many of the health benefits of green tea are mediated through these reactions. Remarkably, all green tea leaves constitutively contain small amounts of H₂S₂.

Prooxidant Effects of Epigallocatechin-3-Gallate in Health Benefits and Potential Adverse Effect

Epigallocatechin-3-gallate (EGCG) is the major polyphenolic compound present in green tea and is generally regarded as an effective antioxidant. However, its chemical reactivity makes it susceptible to generate reactive oxygen species (ROS) via autooxidation and exhibit prooxidant effects. The prooxidant actions of EGCG could play a dual role, being both beneficial and harmful. This review summarized recent research progress on (1) the anticancer, antiobesity, and antibacterial effects of EGCG and (2) the possible toxicity of EGCG. The major focus is on the involvement of prooxidant effects of EGCG and their effective doses used. Considering dosage is a crucial factor in the prooxidant effects of EGCG; further studies are required to find the appropriate dose at which EGCG could bring more health benefits with lower toxicity.

Metal-organic Nanopharmaceuticals

Coordinative interactions between multivalent metal ions and drug derivatives with Lewis base functions give rise to nanoscale coordination polymers (NCPs) as delivery systems. As the pharmacologically active agent constitutes a main building block of the nanomaterial, the resulting drug loadings are typically very high. By additionally selecting metal ions with favorable pharmacological or physicochemical properties, the obtained NCPs are predominantly composed of active components which serve individual purposes, such as pharmacotherapy, photosensitization, multimodal imaging, chemodynamic therapy or radiosensitization. By this approach, the assembly of drug molecules into NCPs modulates pharmacokinetics, combines pharmacological drug action with specific characteristics of metal components and provides a strategy to generate tailorable multifunctional nanoparticles. This article reviews different applications and recent examples of such highly functional nanopharmaceuticals with a high 'material economy'. Lay Summary: Nanoparticles, that are small enough to circulate in the bloodstream and can carry cargo molecules, such as drugs, imaging or contrast agents, are attractive materials for pharmaceutical applications. A high loading capacity is a generally aspired parameter of nanopharmaceuticals to minimize patient exposure to unnecessary nanomaterial. Pharmaceutical agents containing Lewis base functions in their molecular structure can directly be assembled into metal-organic nanopharmaceuticals by coordinative interaction with metal ions. Such coordination polymers generally feature extraordinarily high loading capacities and the flexibility to encapsulate different agents for a simultaneous delivery in combination therapy or 'theranostic' applications.

Involvement of MicroRNA-296 in the Inhibitory Effect of Epigallocatechin Gallate against the Migratory Properties of Anoikis-Resistant Nasopharyngeal Carcinoma Cells

Short noncoding endogenous RNAs, including microRNAs (miRNAs), are associated with the development and metastasis of multiple cancers. Epigallocatechin gallate (EGCG), the most active and abundant polyphenol in green tea, plays a crucial role in the modulation of miRNA expression, which is related to changes in cancer progression. In the present study, we explore whether EGCG exerts its suppressive effects on nasopharyngeal carcinoma (NPC) cells through miRNA regulation. The anoikis-resistant sphere-forming NPC cells grown under anchorage-independent conditions exhibit enhanced migratory properties, which were inhibited by EGCG treatment. The miR-296 level was lower in the anoikis-resistant cells than in the monolayer parental cells; however, miR-296 was significantly upregulated after EGCG treatment. We demonstrate that miR-296 is involved in the inhibitory effects of EGCG on the anoikis-resistant NPC cells through the downregulation of signal transducer and activator of transcription 3 (STAT3) activation. Our study is the first to demonstrate that EGCG inhibited the migratory properties of anoikis-resistant cells by modulating the expression of miRNA in NPC cells. Our results indicate the novel effects of EGCG on miRNA regulation to inhibit an invasive phenotype of NPC as well as the regulatory role of miR-296.

RNA-seq data analysis of stimulated hepatocellular carcinoma cells treated with epigallocatechin gallate and fisetin reveals target genes and action mechanisms

Hepatocellular carcinoma (HCC) is an essentially incurable inflammation-related cancer. We have previously shown by network analysis of proteomic data that the flavonoids epigallocatechin gallate (EGCG) and fisetin (FIS) efficiently downregulated pro-tumor cytokines released by HCC through inhibition of Akt/mTOR/RPS6 phospho-signaling. However, their mode of action at the global transcriptome level remains unclear. Herein, we endeavor to compare gene expression alterations mediated by these compounds through a comprehensive transcriptome analysis based on RNA-seq in HEP3B, a responsive HCC cell line, upon perturbation with a mixture of prototypical stimuli mimicking conditions of tumor microenvironment or under constitutive state.

Analysis of RNA-seq data revealed extended changes on HEP3B transcriptome imposed by test nutraceuticals. Under stimulated conditions, EGCG and FIS significantly modified, compared to the corresponding control, the expression of 922 and 973 genes, respectively, the large majority of which (695 genes), was affected by both compounds. Hierarchical clustering based on the expression data of shared genes demonstrated an almost identical profile in nutraceutical-treated stimulated cells which was virtually opposite in cells exposed to stimuli alone. Downstream enrichment analyses of the co-modified genes uncovered significant associations with cancer-related transcription factors as well as terms of Gene Ontology/Reactome Pathways and highlighted ECM dynamics as a nodal modulation point by nutraceuticals along with angiogenesis, inflammation, cell motility and growth. RNA-seq data for selected genes were independently confirmed by RT-qPCR.

Overall, the present systems approach provides novel evidence stepping up the mechanistic understanding of test nutraceuticals, thus rationalizing their clinical exploitation in new preventive/therapeutic modalities against HCC.

EGCG protects vascular endothelial cells from oxidative stress-induced damage by targeting the autophagy-dependent PI3K-AKT-mTOR pathway

Background

Autophagy plays an important role in cellular homeostasis. Epigallocatechin gallate (EGCG), a polyphenol derived from green tea, has been shown to elicit vascular protective effects. Our study aimed to investigate the protective effect of EGCG in an endothelial injury model induced by hydrogen peroxide (H₂O₂) and reveal the possible mechanisms.

Methods

Human vascular endothelial cells (HUVECs) were pretreatment with different concentration of EGCG, then exposed to H₂O₂. Cell viability was measured with MTS assay. Apoptosis was evaluated with TUNEL staining and apoptosis-related protein was determined by western blot. Autophagy flux was assessed by transmission electron microscopy and LC3 plasmid transfection. Besides, the role mTOR in EGCG-mediated antioxidant responses was validated with siRNA transfection.

Results

The results showed that pretreatment with EGCG significantly improved the survival of HUVECs from H₂O₂-induced cell death. After exposed to H₂O₂, EGCG upregulated the levels of Atg5, Atg7, LC3 II/I, and the Atg5–Atg12 complex in HUVECs, while downregulated apoptosis-related protein. Besides, EGCG inhibited the PI3K-AKT-mTOR signaling pathway. Knockdown of mTOR partially promoted EGCG-induced autophagy.

Conclusions

These results suggest that EGCG induces autophagy by targeting the mTOR pathway, indicating that EGCG has the potential to prevent and treat oxidative stress-related cardiovascular diseases.

(-)-Epigallocatechin-3-gallate provides neuroprotection via AMPK activation against traumatic brain injury in a mouse model

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. (-)-Epigallocatechin-3-gallate (EGCG) has shown robust neuroprotective effects on various brain injury models in rodents. Herein, we aimed to investigate if EGCG protects against TBI and unravel the underlying mechanisms. A total of 102 mice were used for this study. TBI was induced by controlled cortical impact (CCI). EGCG was given immediately after TBI injury. Neurological functions were accessed by corner test, paw placement, modified neurological severity score, rotarod test, and Morris water maze test. AMPK inhibitor and AMPKα1-knockout mice were used to further study the signaling pathways involved in the observed effects. Our results show that EGCG significantly ameliorated CCI-induced neurological impairment, including spatial learning and memory. EGCG suppressed CCI-induced inflammation and oxidative stress. Furthermore, EGCG downregulated the phosphorylation of IKKα/β, IκBα, and nuclear translocation of NF-κB p65; upregulated AMPK phosphorylation; and altered corresponding changes in the phosphorylation of the downstream target's ribosomal protein S6, AS160, and CaMKKß. Our data demonstrate that EGCG protects against CCI-induced TBI through the activation of the AMPK pathway in mice, suggesting that EGCG might be a promising therapeutic intervention preventing locomotor and cognitive impairments after TBI.

Preclinical Pharmacological Activities of Epigallocatechin-3-gallate in Signaling Pathways: An Update on Cancer

Epigallocatechin gallate (EGCG) is the main bioactive component of catechins predominantly present in svarious types of teas. EGCG is well known for a wide spectrum of biological activity as an anti-oxidative, anti-inflammatory, and anti-tumor agent. The effect of EGCG on cell death mechanisms via the induction of apoptosis, necrosis, and autophagy has been documented. Moreover, its anti-proliferative and chemopreventive action has been demonstrated in many cancer cell lines. It was also involved in the modulation of cyclooxygenase-2, in oxidative stress and inflammation of different cell processes. EGCG has been reported as a promising target for plasma membrane proteins, such as epidermal growth factor receptor (EGFR). In addition, it has been demonstrated a mechanism of action relying on the inhibition of ERK1/2, p38 MAPK, NF-κB, and vascular endothelial growth factor (VEGF). EGCG and its derivatives were used in proteasome inhibition and they were involved in epigenetic mechanisms. In summary, EGCG is the most predominant and bioactive constituent of teas and it has a pivotal role in cancer prevention. Its preclinical pharmacological activities are associated with complex molecular mechanisms that involve numerous signaling pathways.

Alleviation of Multidrug Resistance by Flavonoid and Non-Flavonoid Compounds in Breast, Lung, Colorectal and Prostate Cancer

The aim of the manuscript is to discuss the influence of plant polyphenols in overcoming multidrug resistance in four types of solid cancers (breast, colorectal, lung and prostate cancer). Effective treatment requires the use of multiple toxic chemotherapeutic drugs with different properties and targets. However, a major cause of cancer treatment failure and metastasis is the development of multidrug resistance. Potential mechanisms of multidrug resistance include increase of drug efflux, drug inactivation, detoxification mechanisms, modification of drug target, inhibition of cell death, involvement of cancer stem cells, dysregulation of miRNAs activity, epigenetic variations, imbalance of DNA damage/repair processes, tumor heterogeneity, tumor microenvironment, epithelial to mesenchymal transition and modulation of reactive oxygen species. Taking into consideration that synthetic multidrug resistance agents have failed to demonstrate significant survival benefits in patients with different types of cancer, recent research have focused on beneficial effects of natural compounds. Several phenolic compounds (flavones, phenolcarboxylic acids, ellagitannins, stilbens, lignans, curcumin, etc.) act as chemopreventive agents due to their antioxidant capacity, inhibition of proliferation, survival, angiogenesis, and metastasis, modulation of immune and inflammatory responses or inactivation of pro-carcinogens. Moreover, preclinical and clinical studies revealed that these compounds prevent multidrug resistance in cancer by modulating different pathways. Additional research is needed regarding the role of phenolic compounds in the prevention of multidrug resistance in different types of cancer.

Insights on Melatonin as an Active Pharmacological Molecule in Cancer Prevention: What's New?

Along with playing an important role in circadian rhythm, melatonin is thought to play a significant role in preventing cells from damage, as well as in the inhibition of growth and in triggering apoptosis in malignant cells. Its relationship with circadian rhythms, energetic homeostasis, diet, and metabolism, is fundamental to achieve a better comprehension of how melatonin has been considered a chemopreventive molecule, though very few papers dealing with this issue. In this article, we tried to review the most recent evidence regarding the protective as well as the antitumoral mechanisms of melatonin, as related to diet and metabolic balance. From different studies, it was evident that an intracellular antioxidant defense mechanism is activated by upregulating an antioxidant gene battery in the presence of high-dose melatonin in malignant cells. Like other broad-spectrum antioxidant molecules, melatonin plays a vital role in killing tumor cells, preventing metastasis, and simultaneously keeping normal cells protected from oxidative stress and other types of tissue damage.

Effects of Annurca Apple (Malus pumila cv Annurca) Polyphenols on Breast Cancer Cells

Background:

Dietary micronutrients have been proposed as effective inhibitory agents for cancer initiation, progression, and incidence. Among them, polyphenols, present in different foods and beverages, have retained attention in recent years. Apples are among the most consumed fruits worldwide, and several studies suggest that apple polyphenols could play a role in the prevention of degenerative diseases.

Aims and Objectives:

The present study aimed at evaluating the effects of Annurca flesh polyphenols extract (AFPE) effects of proliferation on MCF-7 cells.

Methods:

The data indicated that apple polyphenolic compounds had a significant antiproliferative action on MCF-7 cells and 500μM EqC AFPE induced a cell cycle arrest at G2/M. AFPE was also capable of inducing morphological changes as evidenced by nuclear condensation.

Results:

The cellular, morphological, and molecular data unequivocally suggested that induction of cellular apoptosis was mainly responsible for the previously observed antiproliferation-induced AFPE on MCF-7 cells.

Conclusion:

Taken together, AFPE that acts at a low micromolar range against breast cancer cells may be considered as a promising candidate for anticancer therapy.

Epigallocatechin-3-gallate mouthwash protects mucosa from radiation-induced mucositis in head and neck cancer patients: a prospective, non-randomised, phase 1 trial

Radiation-induced oral mucositis has a dismal outcome with limited treatment options. We conducted a phase I study to evaluate the safety and preliminary efficacy of epigallocatechin-3-gallate (EGCG) mouthwash when given along with radiation in head and neck cancer. Patients with pathologically confirmed head and neck cancer were eligible for this study. EGCG mouthwash was administered at the assigned dosage level (starting at 440 μmol/L, three times a day) in a standard 3 + 3 dose escalation design. Mucosal toxicity, patient satisfaction, and mucositis-related pain (MTP) were assessed weekly. The primary endpoint was safety of EGCG, and the secondary endpoint was to determine the relief of the mucositis symptom. The pre- and post-treatment parameters were compared using the paired t-test. 20 patients were enrolled. The maximum tolerated dose of the EGCG mouthwash was 2200 μmol/L. Burning (n = 1/20) and nausea (n = 3/20) were the most common toxicities. No patients experienced WHO Grade 3 or higher mucositis. MTP scores significantly decreased after EGCG administration over time (p < 0.05). Adding EGCG mouthwash to radiotherapy is feasible without increasing toxicities. The recommended dose for phase II study is determined to be 1760 μmol/L, and EGCG administration reduces radiation-induced oral mucosal injury in patients.

Tea and Its Components Prevent Cancer: A Review of the Redox-Related Mechanism

Cancer is a worldwide epidemic and represents a major threat to human health and survival. Reactive oxygen species (ROS) play a dual role in cancer cells, which includes both promoting and inhibiting carcinogenesis. Tea remains one of the most prevalent beverages consumed due in part to its anti- or pro-oxidative properties. The active compounds in tea, particularly tea polyphenols, can directly or indirectly scavenge ROS to reduce oncogenesis and cancerometastasis. Interestingly, the excessive levels of ROS induced by consuming tea could induce programmed cell death (PCD) or non-PCD of cancer cells. On the basis of illustrating the relationship between ROS and cancer, the current review discusses the composition and efficacy of tea including the redox-relative (including anti-oxidative and pro-oxidative activity) mechanisms and their role along with other components in preventing and treating cancer. This information will highlight the basis for the clinical utilization of tea extracts in the prevention or treatment of cancer in the future.

Enhanced anti-colon cancer efficacy of 5-fluorouracil by epigallocatechin-3- gallate co-loaded in wheat germ agglutinin-conjugated nanoparticles

Colon adenocarcinoma is the third most common cause of cancer-related deaths worldwide owing to its aggressive nature. Here, we developed a novel oral drug delivery system (DDS) that comprised active targeted nanoparticles made from gelatin and chitosan (non-toxic polymers). The nanoparticles were fabricated using a complex coacervation method, which was accompanied by conjugation of wheat germ agglutinin (WGA) onto their surface by glutaraldehyde cross-linking. Specifically, we integrated 5-fluorouracil (5-FU), the first-line treatment agent against colon cancer, and (-)-epigallocatechin-3-gallate (EGCG), which inhibits tumor growth via anti-angiogenesis and apoptosis-inducing effects, into the nanoparticles, named WGA-EF-NP. The 5-FU and EGCG co-loaded nanoparticles showed sustained drug release, enhanced cellular uptake, and longer circulation time. WGA-EF-NP exhibited superior anti-tumor activity and pro-apoptotic efficacy compared to the drugs and nanoparticles without WGA decoration owing to better bioavailability and longer circulation time in vivo. Thus, WGA-EF-NP shows promise as a DDS for enhanced efficacy against colon cancer.

Nutrition and Breast Cancer: A Literature Review on Prevention, Treatment and Recurrence

Breast cancer (BC) is the second most common cancer worldwide and the most commonly occurring malignancy in women. There is growing evidence that lifestyle factors, including diet, body weight and physical activity, may be associated with higher BC risk. However, the effect of dietary factors on BC recurrence and mortality is not clearly understood. Here, we provide an overview of the current evidence obtained from the PubMed databases in the last decade, assessing dietary patterns, as well as the consumption of specific food-stuffs/food-nutrients, in relation to BC incidence, recurrence and survival. Data from the published literature suggest that a healthy dietary pattern characterized by high intake of unrefined cereals, vegetables, fruit, nuts and olive oil, and a moderate/low consumption of saturated fatty acids and red meat, might improve overall survival after diagnosis of BC. BC patients undergoing chemotherapy and/or radiotherapy experience a variety of symptoms that worsen patient quality of life. Studies investigating nutritional interventions during BC treatment have shown that nutritional counselling and supplementation with some dietary constituents, such as EPA and/or DHA, might be useful in limiting drug-induced side effects, as well as in enhancing therapeutic efficacy. Therefore, nutritional intervention in BC patients may be considered an integral part of the multimodal therapeutic approach. However, further research utilizing dietary interventions in large clinical trials is required to definitively establish effective interventions in these patients, to improve long-term survival and quality of life.

Targeting Bacterial Biofilms by the Green Tea Polyphenol EGCG

Bacterial biofilms are multicellular aggregates in which cells are embedded in an extracellular matrix of self-produced biopolymers. Being refractory to antibiotic treatment and host immune systems, biofilms are involved in most chronic infections, and anti-biofilm agents are being searched for urgently. Epigallocatechin-3-gallate (EGCG) was recently shown to act against biofilms by strongly interfering with the assembly of amyloid fibres and the production of phosphoethanolamin-modified cellulose fibrils. Mechanistically, this includes a direct inhibition of the fibre assembly, but also triggers a cell envelope stress response that down-regulates the synthesis of these widely occurring biofilm matrix polymers. Based on its anti-amyloidogenic properties, EGCG seems useful against biofilms involved in cariogenesis or chronic wound infection. However, EGCG seems inefficient against or may even sometimes promote biofilms which rely on other types of matrix polymers, suggesting that searching for 'magic bullet' anti-biofilm agents is an unrealistic goal. Combining molecular and ecophysiological aspects in this review also illustrates why plants control the formation of biofilms on their surfaces by producing anti-amyloidogenic compounds such as EGCG. These agents are not only helpful in combating certain biofilms in chronic infections but even seem effective against the toxic amyloids associated with neuropathological diseases.

Catechins-Modified Selenium-Doped Hydroxyapatite Nanomaterials for Improved Osteosarcoma Therapy Through Generation of Reactive Oxygen Species

Osteosarcoma is the most common bone cancer with limited therapeutic options. It can be treated by selenium-doped hydroxyapatite owing to its known antitumor potential. However, a high concentration of Se is toxic toward normal and stem cells whereas its low concentration cannot effectively remove cancer cells. Therefore, the current study was aimed to improve the anticancer activity of Se-HAp nanoparticles through catechins (CC) modification owing to their high cancer therapeutic value. The sequentially developed catechins modified Se-HAp nanocomposites (CC/Se-HAp) were characterized for various physico-chemical properties and antitumor activity. Structural analysis showed the synthesis of small rod-like single phase HAp nanoparticles (60 ± 15 nm), which effectively interacted with Se and catechins and formed agglomerated structures. TEM analysis showed the internalization and degradation of CC/Se-HAp nanomaterials within MNNG/HOS cells through a non-specific endocytosis process. Cell toxicity analysis showed that catechins modification improved the antitumor activity of Se-HAp nanocomposites by inducing apoptosis of human osteosarcoma MNNG/HOS cell lines, through generation of reactive oxygen species (ROS) which in turn activated the caspase-3 pathway, without significantly affecting the growth of human normal bone marrow stem cells (hBMSCs). qPCR and western blot analyses revealed that casp3, p53, and bax genes were significantly upregulated while cox-2 and PTK-2 were slightly downregulated as compared to control in CC/Se-HAp-treated MNNG/HOS cell lines. The current study of combining natural biomaterial (i.e., catechins) with Se and HAp, can prove to be an effective therapeutic approach for bone cancer therapy.

The therapeutic potential of epigallocatechin‑3‑gallate against human oral squamous cell carcinoma through inhibition of cell proliferation and induction of apoptosis: In vitro and in vivo murine xenograft study

Oral squamous cell carcinoma (OSCC) is one of the most common malignant tumors in the oral region. Despite current therapeutic strategies, the survival rate has not been improved for several decades. Thus, it is important to develop a novel approach for the treatment of OSCC. Epigallocatechin-3-gallate (EGCG) is a major constituent of green tea and has previously been demonstrated to inhibit the growth of several types of cancer cells. However, few studies have investigated the effect of EGCG on human OSCC cells, especially in experimental animal models. The aim of the present study was to evaluate the therapeutic potential of EGCG for targeting human OSCC in vitro and in vivo. In the in vitro experiments, EGCG suppressed HSC-3 cell viability in a time- and dose-dependent manner. Cell cycle analysis revealed that EGCG induced G1 phase arrest of the tumor cells. Apoptosis was examined by Annexin V and propidium iodide staining, assays of caspase-3 and −7 activity and TdT-mediated dUTP nick end labeling (TUNEL) staining. Treatment with EGCG significantly increased caspase-3 and −7 activities, and the percentage of apoptotic cells when compared with control cells. In the in vivo xenograft experiment on mice, EGCG treatment resulted in a 45.2% reduction in tumor size as compared with the control group without weight loss. In vivo cell proliferation and apoptosis were assessed by immunohistochemical Ki-67 staining and the TUNEL staining. There were significant differences in Ki-67 expression between the EGCG treatment group and control group, and the percentage of apoptotic cells in the EGCG treatment group was significantly greater than that in the control group. These results indicated that EGCG significantly inhibited cell proliferation by affecting the cell cycle progression and apoptosis in vitro and in vivo. These findings suggest that EGCG may have clinical applications as a novel approach to oral-cancer therapy.

A review of complementary therapies with medicinal plants for chemotherapy-induced peripheral neuropathy

INTRODUCTION

Chemotherapy-induced peripheral neuropathy (CIPN) is a progressive, prolonged, and often irreversible side effect of many chemotherapeutic agents. The development of neuropathic pain is still poorly managed by clinically available drugs at present.

METHODS

In this mini-review, we summarized the current knowledge of pathobiology for CIPN, and selected evidence on the application of complementary therapies in experimental studies.

RESULTS

Medicinal plants are considered to be the most common complementary therapy modalities for CIPN. Therefore, we identified ten medicinal herbal extracts as well as their phytochemicals, and three herbal formulas. Multiple complementary therapies have been used and studied for decades, and their effects against CIPN are focus on anti-oxidative activity. However, there is still controversial due to the diverse manifestations of different antineoplastic agents and complex drug interactions.

CONCLUSIONS

Novel therapies or drugs that have proven to be effective in animals require further investigation, so confirmation of their efficacy and safety will require time.

Targeting cancer stem cells with dietary phytochemical - Repositioned drug combinations

The tumor microenvironment is complex with the cancer stem cell (CSC) as a member within its community. This population possesses the capacity to self-renew and to cause cellular heterogeneity of the tumor. CSCs are resistant to conventional anti-proliferative drugs. In order to be curative, it is imperative that CSCs must be eliminated by cancer therapy. A variety of dietary phytochemicals and repositioned drugs can act synergistically with conventional anti-cancer agents. In this review, we advocate the development of a novel approach, namely combination therapy by incorporating both phytochemicals and repositioned drugs to target CSCs. We cover select dietary phytochemicals (curcumin, resveratrol, EGCG, genistein) and repurposed drugs (metformin, niclosamide, thioridazine, chloroquine). Five of the eight (curcumin, resveratrol, EGCG, genistein, metformin) are listed in "The Halifax Project", that explores "the concept of a low-toxicity 'broad-spectrum' therapeutic approach that could simultaneously target many key pathways and mechanisms" [1]. For these compounds, we discuss their mechanisms of action, in which models their anti-CSC activities were identified, as well as advantages, challenges and potentials of combination therapy.

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.

Theabrownin triggers DNA damage to suppress human osteosarcoma U2OS cells by activating p53 signalling pathway

Osteosarcoma becomes the second leading cause of cancer death in the younger population. Current outcomes of chemotherapy on osteosarcoma were unsatisfactory to date, demanding development of effective therapies. Tea is a commonly used beverage beneficial to human health. As a major component of tea, theabrownin has been reported to possess anti‐cancer activity. To evaluate its anti‐osteosarcoma effect, we established a xenograft model of zebrafish and employed U2OS cells for in vivo and in vitro assays. The animal data showed that TB significantly inhibited the tumour growth with stronger effect than that of chemotherapy. The cellular data confirmed that TB‐triggered DNA damage and induced apoptosis of U2OS cells by regulation of Mki67, PARP, caspase 3 and H2AX, and Western blot assay showed an activation of p53 signalling pathway. When P53 was knocked down by siRNA, the subsequent downstream signalling was blocked, indicating a p53‐dependent mechanism of TB on U2OS cells (p53 wt). Using osteosarcoma cell lines with p53 mutations (HOS, SAOS‐2 and MG63), we found that TB exerted stronger inhibitory effect on U2OS cells than that on p53‐mut cell lines, but it also exerted obvious effect on SAOS‐2 cells (p53 null), suggesting an activation of p53‐independent pathway in the p53‐null cells. Interestingly, theabrownin was found to have no toxicity on normal tissue in vivo and could even increase the viability of p53‐wt normal cells. In sum, theabrownin could trigger DNA damage and induce apoptosis on U2OS cells via a p53‐dependent mechanism, being a promising candidate for osteosarcoma therapy.

Nutrients, Nutraceuticals, and Xenobiotics Affecting Renal Health

Chronic kidney disease (CKD) affects 8–16% of the population worldwide. In developed countries, the most important risk factors for CKD are diabetes, hypertension, and obesity, calling into question the importance of educating and acting on lifestyles and nutrition. A balanced diet and supplementation can indeed support the maintenance of a general health status, including preservation of renal function, and can help to manage and curb the main risk factors for renal damage. While the concept of protein and salt restriction in nephrology is historically acknowledged, the role of some nutrients in renal health and the importance of nutrition as a preventative measure for renal care are less known. In this narrative review, we provide an overview of the demonstrated and potential actions of some selected nutrients, nutraceuticals, and xenobiotics on renal health and function. The direct and indirect effects of fiber, protein, fatty acids, curcumin, steviol glycosides, green tea, coffee, nitrates, nitrites, and alcohol on kidney health are reviewed here. In view of functional and personalized nutrition, understanding the renal and systemic effects of dietary components is essential since many chronic conditions, including CKD, are related to systemic dysfunctions such as chronic low-grade inflammation.

Neuroprotective action of tea polyphenols on oxidative stress-induced apoptosis through the activation of the TrkB/CREB/BDNF pathway and Keap1/Nrf2 signaling pathway in SH-SY5Y cells and mice brain

Many studies have shown that oxidative stress is a major cause of cellular injuries in a variety of human diseases including cognitive impairment. Tea polyphenols (TPs), natural plant flavonoids found in tea plant leaves, possess the bioactivity to affect the pathogenesis of several chronic diseases via antioxidant associated mechanisms. However, the possible antioxidant and neuroprotective properties of TPs in the brain of mice housed in constant darkness and in H₂O₂-stimulated SH-SY5Y cells are yet to be elucidated. In this study, pretreatment with TPs markedly attenuated H₂O₂-elicited cell viability loss and mitochondrial dysfunction, suppressed the induced apoptosis and reduced the elevated levels of intracellular ROS and H₂O₂. Additionally, TPs modulate the nuclear translocation of Nrf2 and the TrkB/CREB/BDNF signaling pathway by provoking the PI3K/AKT pathway and thus, they transcriptionally regulate the downstream expression of antioxidant enzymes including HO-1, NQO-1, and BDNF in SH-SY5Y cells. Furthermore, an in vivo study revealed that housing mice in constant darkness, simulating shift work disruption in humans, notably affects the AKT/CREB/BDNF signal pathway and the nuclear translocation of Nrf2 and its downstream phase II detoxification enzymes in brain tissue. Remarkably, TP supplementation through drinking water eliminated these changes. These results suggest that TPs possess protective effects against oxidative stress-triggered cognitive impairment, which might be a potential nutritional preventive strategy for neurodegenerative diseases implicated with oxidative stress in shift workers.

Differences in the Effects of EGCG on Chromosomal Stability and Cell Growth between Normal and Colon Cancer Cells

The tea catechin epigallocatechin-3-gallate (EGCG) proved to be the most potent physiologically active tea compound in vitro. It possesses antioxidant as well as pro-oxidant properties. EGCG has the effect of inducing apoptosis of tumor cells and inhibiting cell proliferation. Whether this effect is associated with the antioxidant or pro-oxidative effects of EGCG affecting the genome stability of normal and cancer cells has not been confirmed. Here, we selected Human normal colon epithelial cells NCM460 and colon adenocarcinoma cells COLO205 to investigate the effects of EGCG (0–40 μg/mL) on the genome stability and cell growth status. Chromosomal instability (CIN), nuclear division index (NDI), and apoptosis was measured by cytokinesis-block micronucleus assay (CBMN), and the expression of core genes in mismatch repair (hMLMLH1 and hMSH2) was examined by RT-qPCR. We found that EGCG significantly reduced CIN and apoptosis rate of NCM460 at all concentrations (5–40 μg/mL) and treatment time, EGCG at 5 μg/mL promoted cell division; EGCG could significantly induce chromosome instability in COLO205 cells and trigger apoptosis and inhibition of cell division. These results suggest that EGCG exhibits different genetic and cytological effects in normal and colon cancer cells.

Inducers of Senescence, Toxic Compounds, and Senolytics: The Multiple Faces of Nrf2-Activating Phytochemicals in Cancer Adjuvant Therapy

The reactivation of senescence in cancer and the subsequent clearance of senescent cells are suggested as therapeutic intervention in the eradication of cancer. Several natural compounds that activate Nrf2 (nuclear factor erythroid-derived 2-related factor 2) pathway, which is involved in complex cytoprotective responses, have been paradoxically shown to induce cell death or senescence in cancer. Promoting the cytoprotective Nrf2 pathway may be desirable for chemoprevention, but it might be detrimental in later stages and advanced cancers. However, senolytic activity shown by some Nrf2-activating compounds could be used to target senescent cancer cells (particularly in aged immune-depressed organisms) that escape immunosurveillance. We herein describe in vitro and in vivo effects of fifteen Nrf2-interacting natural compounds (tocotrienols, curcumin, epigallocatechin gallate, quercetin, genistein, resveratrol, silybin, phenethyl isothiocyanate, sulforaphane, triptolide, allicin, berberine, piperlongumine, fisetin, and phloretin) on cellular senescence and discuss their use in adjuvant cancer therapy. In light of available literature, it can be concluded that the meaning and the potential of adjuvant therapy with natural compounds in humans remain unclear, also taking into account the existence of few clinical trials mostly characterized by uncertain results. Further studies are needed to investigate the therapeutic potential of those compounds that display senolytic activity.

Biophysical evidence for differential gallated green tea catechins binding to membrane type-1 matrix metalloproteinase and its interactors

Membrane type-1 matrix metalloproteinase (MT1-MMP) is a transmembrane MMP which triggers intracellular signaling and regulates extracellular matrix proteolysis, two functions that are critical for tumor-associated angiogenesis and inflammation. While green tea catechins, particularly epigallocatechin gallate (EGCG), are considered very effective in preventing MT1-MMP-mediated functions, lack of structure-function studies and evidence regarding their direct interaction with MT1-MMP-mediated biological activities remain. Here, we assessed the impact in both cellular and biophysical assays of four ungallated catechins along with their gallated counterparts on MT1-MMP-mediated functions and molecular binding partners. Concanavalin-A (ConA) was used to trigger MT1-MMP-mediated proMMP-2 activation, expression of MT1-MMP and of endoplasmic reticulum stress biomarker GRP78 in U87 glioblastoma cells. We found that ConA-mediated MT1-MMP induction was inhibited by EGCG and catechin gallate (CG), that GRP78 induction was inhibited by EGCG, CG, and gallocatechin gallate (GCG), whereas proMMP-2 activation was inhibited by EGCG and GCG. Surface plasmon resonance was used to assess direct interaction between catechins and MT1-MMP interactors. We found that gallated catechins interacted better than their ungallated analogs with MT1-MMP as well as with MT1-MMP binding partners MMP-2, TIMP-2, MTCBP-1 and LRP1-clusterIV. Overall, current structure-function evidence supports a role for the galloyl moiety in both direct and indirect interactions of green tea catechins with MT1-MMP-mediated oncogenic processes.

Administration of antioxidants in cancer: debate of the decade

Several randomized clinical trials have divulged that administration of antioxidants during chemotherapy decreases the effectiveness of treatment. Hence, the characteristic feature of this article is extensive assessment of putative benefits and potential risks of natural and synthetic antioxidant supplementation, administered with chemotherapy, based upon the available preclinical and clinical data. After analyzing mixed results, it was concluded that current FDA guidelines should be followed before supplementing antioxidants during cytotoxic treatment. Nevertheless, contradictory experimental animal models opposing human clinical trials discourage the concurrent administration of antioxidants ostensibly owing to the possibility of tumor protection and reduced survival.

Antiangiogenic Effect of Flavonoids and Chalcones: An Update

Chalcones are precursors of flavonoid biosynthesis in plants. Both flavonoids and chalcones are intensively investigated because of a large spectrum of their biological activities. Among others, anticancer and antiangiogenic effects account for the research interest of these substances. Because of an essential role in cancer growth and metastasis, angiogenesis is considered to be a promising target for cancer treatment. Currently used antiangiogenic agents are either synthetic compounds or monoclonal antibodies. However, there are some limitations of their use including toxicity and high price, making the search for new antiangiogenic compounds very attractive. Nowadays it is well known that several natural compounds may modulate basic steps in angiogenesis. A lot of studies, also from our lab, showed that phytochemicals, including polyphenols, are potent modulators of angiogenesis. This review paper is focused on the antiangiogenic effect of flavonoids and chalcones and discusses possible underlying cellular and molecular mechanisms.

Enhancement of cisplatin cytotoxicity by Retigeric acid B involves blocking DNA repair and activating DR5 in prostate cancer cells

Retigeric acid B (RAB), a natural compound isolated from lichen, has been demonstrated to inhibit cell growth and promote apoptosis in prostate cancer (PCa) cells. The present study evaluated the function of RAB combined with clinical chemotherapeutic drugs in PCa cell lines by MTT assay, reverse transcription quantitative polymerase chain reaction and western blot analysis, and identified that RAB at low doses produced significant synergistic cytotoxicity in combination with cisplatin (CDDP); however, no marked synergism between RAB and the other chemotherapeutics was observed. Additional studies revealed that RAB exerted an inhibitory effect on DNA damage repair pathways, including the nucleotide excision repair and mismatch repair pathways, which are involved in the sensitivity to CDDP-based chemotherapy, as suggested by the significantly downregulated expression of certain associated repair proteins. Notably, Excision repair cross-complementing 1, a critical gene in the nucleotide excision repair pathway, exhibited the most significant decrease. When combined with CDDP, RAB-mediated impairment of DNA repair resulted in prolonged DNA damage, as demonstrated by the long-lasting appearance of phosphorylation of histone H2AX at Ser139, which potentially enhanced the chemosensitivity to CDDP. Concurrently, the proapoptotic protein death receptor 5 (DR5) was activated by RAB, which also enhanced the chemotherapeutic response of CDDP. Knockdown of DR5 partially blocked RAB-CDDP synergism, suggesting the crucial involvement of DR5 in this event. The results of the present study identified that RAB functioned synergistically with CDDP to increase the efficacy of CDDP by inhibiting DNA damage repair and activating DR5, suggesting the mechanistic basis for the antitumor effect of RAB in combination with current chemotherapeutics.

Ameliorated Effects of (-)-Epigallocatechin Gallate Against Toxicity Induced by Vanadium in the Kidneys of Wistar Rats

The aim of the study was to assess the protective effect of (-)-epigallocatechin gallate (EGCG), a flavonoid abundant in green tea, against ammonium metavanadate (AMV)-induced oxidative stress in male Wistar rats. Four groups of animals have been used, a control group and three test groups. In the first test group, AMV was intra-peritoneally (i.p) injected daily (5 mg/kg body weight for five consecutive days). The second test group of animals was also injected daily with EGCG (5 mg/kg body weight) during the same period. However, the third test group was i.p. injected with both AMV and EGCG (5 mg/kg body weight for five consecutive days). When given alone, AMV induced an oxidative stress evidenced by an increase of lipid peroxidation levels (expressed as TBARS concentration) in kidney. In these animals, activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) were significantly decreased, suggesting significant reduction of the antioxidant defense system at the cell level. Kidney histological sections, showed glomerular hypertrophy and tubular dilatation. In AMV-treated animals receiving EGCG, the oxidative stress was much less pronounced and activities of antioxidant enzymes were kept close to control values. Histopathological changes were less prominent. Our results confirm that green tea and other sources of flavonoids might confer a strong protection against ammonium metavanadate-induced oxidative stress.