Chemoprevention of head and neck cancer with green tea polyphenols

Oxidative Stress and Dietary Antioxidants in Head and Neck Cancer

Oxidative stress serves as both a driver and result of redox metabolism across diverse physiological and pathological states, including cancer. Head and neck squamous cell carcinoma (HNSCC), the sixth most prevalent malignancy worldwide, is no exception. HNSCC is strongly linked to modifiable external risk factors such as tobacco smoking, alcohol consumption, and high-risk human papilloma (HR-HPV) infection. These risk factors are associated with elevated oxidative stress, which contributes to carcinogenesis through DNA damage, chronic inflammation, and dysregulation of cell signaling pathways. Current treatment options for HNSCC have limitations and burden of side effects. Studies have been conducted on potent dietary antioxidants for the prevention and adjunctive treatment of HNSCC. This review aims to explore the contribution of oxidative stress to carcinogenesis in general and the three major risk factors for HNSCC. We evaluate latest evidence for nine dietary antioxidants such as vitamin C, vitamin E, carotenoids, epigallocatechin-3-gallate (EGCG), and curcumin, that have shown promise in preclinical and clinical studies. We discuss how these compounds mitigate ROS, influence cancer-related signaling pathways, and modulate tumor microenvironment. Despite encouraging findings, current clinical data remain limited and inconclusive, highlighting the need for further research on possible dietary antioxidants for HNSCC.

Dietary plants for oral cancer prevention and therapy: A review of preclinical and clinical studies

Oral cancer is a disease with high mortality and rising incidence worldwide. Although fragmentary literature on the anti-oral cancer effects of plant products has been published, a comprehensive analysis is lacking. In this work, a critical and comprehensive evaluation of oral cancer preventative or therapeutic effects of dietary plants was conducted. An exhaustive analysis of available data supports that numerous dietary plants exert anticancer effects, including suppression of cell proliferation, viability, autophagy, angiogenesis, invasion, and metastasis while promoting cell cycle arrest and apoptosis. Plant extracts and products target several cellular mechanisms, such as the reversal of epithelial-to-mesenchymal transition and the promotion of oxidative stress and mitochondrial membrane dysfunction by modulation of various signaling pathways. These agents were also found to regulate cellular growth signaling pathways by action on extracellular signal-regulated kinase and mitogen-activated protein kinase, inflammation via modulation of cyclooxygenase (COX)-1, COX-2, and nuclear factor-κB p65, and metastasis through influence of cadherins and matrix metalloproteinases. In vivo studies support these findings and demonstrate a decrease in tumor burden, incidence, and hyperplastic and dysplastic changes. Clinical studies also showed decreased oral cancer risk. However, high-quality studies should be conducted to establish the clinical efficacy of these plants. Overall, our study supports the use of dietary plants, especially garlic, green tea, longan, peppermint, purple carrot, saffron, tomato, and turmeric, for oral cancer prevention and intervention. However, further research is required before clinical application of this strategy.

Optimizing rosemary oil nanoemulsion loaded with nelfinavir and epigallocatechin gallate: A Design Expert® endorsed approach for enhanced neuroAIDS management

This study focuses on optimizing the delivery of Nelfinavir (NFV), a vital protease inhibitor in antiretroviral therapy, and Epigallocatechin gallate (EGCG), a potent adjunctive anti- human immunodeficiency virus (anti-HIV) agent found in green tea. The challenge lies in NFV's low intrinsic dissolution rate, significant p-gp efflux, and high hepatic metabolism, necessitating frequent and high-dose administration. Our objective was to develop a nanoemulsion loaded with NFV and EGCG to enhance oral delivery, expediting antiretroviral effects for NeuroAIDS treatment. After meticulous excipient screening, we selected Tween 40 as the surfactant and polyethylene glycol 400 (PEG 400) as the co-surfactant. Employing a Quality by Design (QbD) approach with statistical multivariate methods, we optimized the nanoemulsion that exhibited a droplet size of 83.21 nm, polydispersity index (PDI) of 2.289, transmittance of 95.20 %, zeta potential of 1.495 mV, pH of 6.95, refractive index of 1.40, viscosity of 24.00 ± 0.42 mPas, and conductivity of 0.162 μS/cm. Pharmacokinetic studies demonstrated superior in vivo absorption of the optimized nanoemulsion compared to NFV and EGCG suspension. The optimized nanoemulsion showcased higher Cmax of NFV (9.75 ± 1.23 μg/mL) and EGCG (27.7 ± 1.22 μg/mL) in the brain, along with NFV (26.44 ± 1.44 μg/mL) and EGCG (313.20 ± 5.53 μg/mL) in the plasma. This study advocates for the potential of NFV and EGCG-loaded nanoemulsion in combination antiretroviral therapy (cART) for effective NeuroAIDS management.

Computational insights into the stereo-selectivity of catechins for the inhibition of the cancer therapeutic target EGFR kinase

The epidermal growth factor receptor (EGFR) plays a crucial role in regulating cellular growth and survival, and its dysregulation is implicated in various cancers, making it a prime target for cancer therapy. Natural compounds known as catechins have garnered attention as promising anticancer agents. These compounds exert their anticancer effects through diverse mechanisms, primarily by inhibiting receptor tyrosine kinases (RTKs), a protein family that includes the notable member EGFR. Catechins, characterized by two chiral centers and stereoisomerism, demonstrate variations in chemical and physical properties due to differences in the spatial orientation of atoms. Although previous studies have explored the membrane fluidity effects and transport across cellular membranes, the stereo-selectivity of catechins concerning EGFR kinase inhibition remains unexplored. In this study, we investigated the stereo-selectivity of catechins in inhibiting EGFR kinase, both in its wild-type and in the prevalent L858R mutant. Computational analyses indicated that all stereoisomers, including the extensively studied catechin (-)-EGCG, effectively bound within the ATP-binding site, potentially inhibiting EGFR kinase activity. Notably, gallated catechins emerged as superior EGFR inhibitors to their non-gallated counterparts, revealing intriguing binding trends. The top four stereoisomers exhibiting high dock scores and binding energies with wild-type EGFR comprise (-)-CG (-)-GCG (+)-CG, and (-)-EGCG. To assess dynamic behavior and stability, molecular dynamics simulations over 100 ns were conducted for the top-ranked catechin (-)-CG and the widely investigated catechin (-)-EGCG with EGFR kinase. This study enhances our understanding of how the stereoisomeric nature of a drug influences inhibitory potential, providing insights that could guide the selection of specific stereoisomers for improved efficacy inexisting drugs.

Bioactive phytocompounds for oral cancer prevention and treatment: A comprehensive and critical evaluation

The high incidence of oral cancer combined with excessive treatment cost underscores the need for novel oral cancer preventive and therapeutic options. The value of natural agents, including plant secondary metabolites (phytochemicals), in preventing carcinogenesis and representing expansive source of anticancer drugs have been established. While fragmentary research data are available on antioral cancer effects of phytochemicals, a comprehensive and critical evaluation of the potential of these agents for the prevention and intervention of human oral malignancies has not been conducted according to our knowledge. This study presents a complete and critical analysis of current preclinical and clinical results on the prevention and treatment of oral cancer using phytochemicals. Our in-depth analysis highlights anticancer effects of various phytochemicals, such as phenolics, terpenoids, alkaloids, and sulfur-containing compounds, against numerous oral cancer cells and/or in vivo oral cancer models by antiproliferative, proapoptotic, cell cycle-regulatory, antiinvasive, antiangiogenic, and antimetastatic effects. Bioactive phytochemicals exert their antineoplastic effects by modulating various signaling pathways, specifically involving the epidermal growth factor receptor, cytokine receptors, toll-like receptors, and tumor necrosis factor receptor and consequently alter the expression of downstream genes and proteins. Interestingly, phytochemicals demonstrate encouraging effects in clinical trials, such as reduction of oral lesion size, cell growth, pain score, and development of new lesions. While most phytochemicals displayed minimal toxicity, concerns with bioavailability may limit their clinical application. Future directions for research include more in-depth mechanistic in vivo studies, administration of phytochemicals using novel formulations, investigation of phytocompounds as adjuvants to conventional treatment, and randomized clinical trials.

Treating Head and Neck Cancer in the Age of Immunotherapy: A 2023 Update

Most patients diagnosed with head and neck squamous cell carcinoma (HNSCC) will present with locally advanced disease, requiring multimodality therapy. While this approach has a curative intent, a significant subset of these patients will develop locoregional failure and/or distant metastases. The prognosis of these patients is poor, and therapeutic options other than palliative chemotherapy are urgently needed. Epidermal growth factor receptor (EGFR) overexpression is an important factor in the pathogenesis of HNSCC, and a decade ago, the EGFR targeting monoclonal antibody cetuximab was approved for the treatment of late-stage HNSCC in different settings. In 2016, the anti-programmed death-1 (PD-1) immune checkpoint inhibitors nivolumab and pembrolizumab were both approved for the treatment of patients with recurrent or metastatic HNSCC with disease progression on or after platinum-containing chemotherapy, and in 2019, pembrolizumab was approved for first-line treatment (either as monotherapy in PD-L1 expressing tumors, or in combination with chemotherapy). Currently, trials are ongoing to include immune checkpoint inhibition in the (neo)adjuvant treatment of HNSCC as well as in novel combinations with other drugs in the recurrent/metastatic setting to improve response rates and survival and help overcome resistance mechanisms to immune checkpoint blockade. This article provides a comprehensive review of the management of head and neck cancers in the current era of immunotherapy.

Combination of resveratrol and green tea epigallocatechin gallate induces synergistic apoptosis and inhibits tumor growth in vivo in head and neck cancer models

Despite widespread interest in chemoprevention and therapy due to the high margin of safety of dietary natural compounds, clinical intervention with single agents has failed to yield the expected outcomes, mostly due to poor bioavailability and low potency. Combinations of natural agents with synergistic effects are gaining increasing attention. In the present study, in vitro and in vivo antitumor effects of a combination of two natural dietary agents, green tea epigallocatechin gallate (EGCG) and resveratrol were investigated. It was revealed that their combination at low doses (at which single agents induce minimal apoptosis) synergistically increased apoptosis (combination index <1) in head and neck cancer cell lines. Synergistic apoptosis was also supported by caspase-3 and PARP cleavage. The combination also significantly inhibited growth of xenografted head and neck tumors in nude mice as supported by significant inhibition of tumor volume, tumor weight and Ki67 expression, and increase in TUNEL-positive cells. Mechanistic studies revealed that the combination inhibited AKT-mTOR signaling both in vitro and in vivo. In addition, overexpression of constitutively active AKT protected cells from apoptosis induced by the combination of EGCG and resveratrol. Collectively, the present results for the first time suggest that the combination of EGCG and resveratrol has synergistic growth inhibitory effects and provide an important rationale for future clinical development for chemoprevention and treatment of head and neck cancer.

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.

Wine Consumption and Oral Cavity Cancer: Friend or Foe, Two Faces of Janus

The health benefits of moderate wine consumption have been extensively studied during the last few decades. Some studies have demonstrated protective associations between moderate drinking and several diseases including oral cavity cancer (OCC). However, due to the various adverse effects related to ethanol content, the recommendation of moderate wine consumption has been controversial. The polyphenolic components of wine contribute to its beneficial effects with different biological pathways, including antioxidant, lipid regulating and anti-inflammatory effects. On the other hand, in the oral cavity, ethanol is oxidized to form acetaldehyde, a metabolite with genotoxic properties. This review is a critical compilation of both the beneficial and the detrimental effects of wine consumption on OCC.

Nutrition and Liver Cancer Prevention

Liver cancer represents a major public health problem. Hepatocarcinogenesis is a complex process that comprises several stages and is caused by multiple factors. Both progressive genetic and epigenetic alterations are described in liver cancer development. The most effective strategy to reduce the impact of this disease is through prevention. In addition to vaccination against HBV and treatment of HCV infection, other preventive measures include avoiding ingesting aflatoxin-contaminated foods and drinking alcoholic beverages, as well as maintaining healthy body weight and practicing physical exercise. Bioactive compounds from fruits and vegetables present great potential for liver cancer chemoprevention. Among them, tea catechins, carotenoids, retinoids, β-ionone, geranylgeraniol and folic acid can be highlighted. In addition, butyric acid, tributyrin and structured lipids based on butyric acid and other fatty acids represent additional promising chemopreventive agents. These bioactive food compounds have been shown to modulate key cellular and molecular processes that are deregulated in hepatocarcinogenesis. Furthermore, combinations of different classes of bioactive food compounds or of bioactive food compounds with synthetic drugs could lead to synergistic liver cancer chemopreventive effects.

Chemoprevention of Head and Neck Cancers: Does It Have Only One Face?

Head and neck squamous cell cancer (HNSCC) represents a significant burden worldwide. Chemoprevention of HNSCC is a means of cancer control with a use of drugs or natural agents in order to hinder or delay the cancer development. The purpose of this article is to review mechanism of action of different chemopreventive agents' groups and results of most important researches concerning them. The safety issues of HNSCC chemoprevention are also discussed. In case of HNSCC there is currently no agent, which would give positive result in the third phase of clinical trials. Promising results of preclinical trials are not always confirmed by further tests. Main problems are low effectiveness, high toxicity, and lack of highly specificity biomarkers for monitoring the research. New trials concerning many agents, as well as novel technologies for provision of pharmaceutical forms of them, including drug nanocarriers, are currently underway, which gives hope for finding the perfect chemopreventive agent formula.

A Review of Promising Natural Chemopreventive Agents for Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) accounts for 300,000 deaths per year worldwide, and overall survival rates have shown little improvement over the past three decades. Current treatment methods including surgery, chemotherapy, and radiotherapy leave patients with secondary morbidities. Thus, treatment of HNSCC may benefit from exploration of natural compounds as chemopreventive agents. With excellent safety profiles, reduced toxicities, antioxidant properties, and general acceptance for use as dietary supplements, natural compounds are viewed as a desirable area of investigation for chemoprevention. Though most of the field is early in development, numerous studies display the potential utility of natural compounds against HNSCC. These compounds face additional challenges such as low bioavailability for systemic delivery, potential toxicities when consumed in pharmacologic doses, and acquired resistance. However, novel delivery vehicles and synthetic analogues have shown to overcome some of these challenges. This review covers 11 promising natural compounds in the chemoprevention of HNSCC including vitamin A, curcumin, isothiocyanate, green tea, luteolin, resveratrol, genistein, lycopene, bitter melon, withaferin A, and guggulsterone. The review discusses the therapeutic potential and associated challenges of these agents in the chemopreventive efforts against HNSCC. Cancer Prev Res; 11(8); 441-50. ©2018 AACR.

Cancer chemoprevention and therapy using chinese herbal medicine

Traditional Chinese medicine (TCM) plays an indispensable role in cancer prevention and treatment. Chinese herbal medicine (CHM) is a key component of TCM and has been practiced for thousands of years. A number of naturally occurring products from Chinese herbs extracts exhibit strong inhibitory properties against carcinogenesis, including CHM single-herb extracts, CHM-derived active components, and CHM formulas (the polyherbal combinations), which regulate JAK/STAT, MAPK, and NF-ҡB pathways. The present review aims to report the cancer-preventive effect of CHM with evidence from cell-line, animal, epidemiological, and clinical experiments. We also present several issues that have yet to be resolved. In the future, cancer prevention by CHM will face unprecedented opportunities and challenges.

(-)-Epigallocatechin-3-gallate inhibition of Epstein-Barr virus spontaneous lytic infection involves downregulation of latent membrane protein 1

The Epstein-Barr virus (EBV) lytic cycle contributes to the development of EBV-associated diseases. EBV-encoded latent membrane protein 1 (LMP1) is key to EBV lytic replication, and our previous work indicated that epigallocatechin-3-gallate (EGCG) inhibited constitutive EBV lytic infection through the suppression of LMP1-activated phosphoinositide 3-kinase/Akt and mitogen-activated protein kinase kinase/extracellular signal-related protein kinase 1/2 signaling. The present study demonstrated that LMP1 in CNE-LMP1 constructed cells significantly induced the expression of the EBV lytic proteins BZLF1 (P<0.001) and BMRF1 (P<0.05) compared with CNE1 cells. Following treatment with a specific DNAzyme that targets LMP1, significantly reduced protein expression levels of BZLF1 and BMRF1 in EBV-associated epithelial carcinoma CNE1-LMP1 cells (P<0.001 and P<0.01, respectively) and lymphoma B95.8 cells (both P<0.01) were observed. Furthermore, EGCG significantly inhibited the mRNA and protein expression levels of LMP1 (P<0.05) in an apparent dose-dependent manner in CNE1-LMP1 and B95.8 cells. Thus, the present findings indicated that the molecular mechanism underlying EGCG inhibition of EBV lytic infection involves downregulation of LMP1.

Novel Molecular Targets for Chemoprevention in Malignancies of the Head and Neck

Cancers of the head and neck region are among the leading causes of cancer-related mortalities worldwide. Oral leukoplakia and erythroplakia are identified as precursor lesions to malignancy. Patients cured of an initial primary head and neck cancer are also susceptible to developing second primary tumors due to cancerization of their mucosal field. Multi-step acquisition of genetic mutations leading to tumorigenesis and development of invasive cancer has been previously described. Recently, whole exome sequencing of tumor specimens has helped to identify driver mutations in this disease. For these reasons, chemoprevention or the use of systemic or biologic agents to prevent carcinogenesis is an attractive concept in head and neck cancers. Nonetheless, despite extensive clinical research in this field over the past couple decades, no standard of care option has emerged. This review article reports on targeted interventions that have been attempted in clinical trials to date, and focuses on novel molecular pathways and drugs in development that are worthy of being tested for this indication as part of future endeavors.

Tapirira guianensis Aubl. Extracts Inhibit Proliferation and Migration of Oral Cancer Cells Lines

Cancer of the head and neck is a group of upper aerodigestive tract neoplasms in which aggressive treatments may cause harmful side effects to the patient. In the last decade, investigations on natural compounds have been particularly successful in the field of anticancer drug research. Our aim is to evaluate the antitumor effect of Tapirira guianensis Aubl. extracts on a panel of head and neck squamous cell carcinoma (HNSCC) cell lines. Analysis of secondary metabolites classes in fractions of T. guianensis was performed using Nuclear Magnetic Resonance (NMR). Mutagenicity effect was evaluated by Ames mutagenicity assay. The cytotoxic effect, and migration and invasion inhibition were measured. Additionally, the expression level of apoptosis-related molecules (PARP, Caspases 3, and Fas) and MMP-2 was detected using Western blot. Heterogeneous cytotoxicity response was observed for all fractions, which showed migration inhibition, reduced matrix degradation, and decreased cell invasion ability. Expression levels of MMP-2 decreased in all fractions, and particularly in the hexane fraction. Furthermore, overexpression of FAS and caspase-3, and increase of cleaved PARP indicates possible apoptosis extrinsic pathway activation. Antiproliferative activity of T. guianensis extract in HNSCC cells lines suggests the possibility of developing an anticancer agent or an additive with synergic activities associated with conventional anticancer therapy.

Proapoptotic Activity of Propolis and Their Components on Human Tongue Squamous Cell Carcinoma Cell Line (CAL-27)

Propolis has been used since ancient times in folk medicine. It is a popular medicine possessing a broad spectrum of biological activities. This material is one of the richest sources of polyphenolic compounds such as flavonoids and phenolic acids. The ethanolic extract of propolis (EEP) evokes antibacterial, antiviral, antifungal and anticancer properties. Due to pharmacological properties it is used in the commercial production of nutritional supplements. In this study, gas chromatography coupled with mass spectrometry (GC-MS) was used to quantify main polyphenols in EEPs. The effect of EEPs, individual EEPs components (chrysin, galangin, pinocembrin, caffeic acid, p-coumaric acid, ferulic acid) and their mixture on viability of human tongue squamous cell carcinoma cell line (CAL-27) as well as the molecular mechanisms of the process were examined. The results of MTTs assay demonstrated that EEP, polyphenols and mixture of polyphenolic compounds were cytotoxic for CAL-27 cells in a dose dependent manner. The mechanism of cytotoxicity induced by these components undergoes through apoptosis as detected by flow cytometry. The ethanolic extracts of propolis activated caspases -3, -8, -9. Mixture of polyphenols was found as the most potent inducer of apoptosis thorough both intrinsic and extrinsic pathway. Therefore, we suggest that anticancer properties of propolis is related to synergistic activity of its main components.

Synergistic effect of curcumin on epigallocatechin gallate-induced anticancer action in PC3 prostate cancer cells

Epigallocatechin gallate (EGCG) and curcumin are well known to naturally-occurring anticancer agents. The aim of this study was to verify the combined beneficial anticancer effects of curcumin and EGCG on PC3 prostate cancer cells, which are resistant to chemotherapy drugs and apoptosis inducers. EGCG showed weaker inhibitory effect on PC3 cell proliferation than two other prostate cancer cell lines, LNCaP and DU145. Co-treatment of curcumin improved antiproliferative effect of EGCG on PC3 cells. The protein expressions of p21 were significantly increased by the co-treatment of EGCG and curcumin, whereas it was not changed by the treatment with each individual compound. Moreover, treatments of EGCG and curcumin arrested both S and G2/M phases of PC3 cells. These results suggest that the enhanced inhibitory effect of EGCG on PC3 cell proliferation by curcumin was mediated by the synergic up-regulation of p21-induced growth arrest and followed cell growth arrest. [BMB Reports 2015; 48(8): 461-466]

Regulation of the Telomerase Reverse Transcriptase Subunit through Epigenetic Mechanisms

Chromosome-shortening is characteristic of normal cells, and is known as the end replication problem. Telomerase is the enzyme responsible for extending the ends of the chromosomes in de novo synthesis, and occurs in germ cells as well as most malignant cancers. There are three subunits of telomerase: human telomerase RNA (hTERC), human telomerase associated protein (hTEP1), or dyskerin, and human telomerase reverse transcriptase (hTERT). hTERC and hTEP1 are constitutively expressed, so the enzymatic activity of telomerase is dependent on the transcription of hTERT. DNA methylation, histone methylation, and histone acetylation are basic epigenetic regulations involved in the expression of hTERT. Non-coding RNA can also serve as a form of epigenetic control of hTERT. This epigenetic-based regulation of hTERT is important in providing a mechanism for reversibility of hTERT control in various biological states. These include embryonic down-regulation of hTERT contributing to aging and the upregulation of hTERT playing a critical role in over 90% of cancers. Normal human somatic cells have a non-methylated/hypomethylated CpG island within the hTERT promoter region, while telomerase-positive cells paradoxically have at least a partially methylated promoter region that is opposite to the normal roles of DNA methylation. Histone acetylation of H3K9 within the promoter region is associated with an open chromatin state such that transcription machinery has the space to form. Histone methylation of hTERT has varied control of the gene, however. Mono- and dimethylation of H3K9 within the promoter region indicate silent euchromatin, while a trimethylated H3K9 enhances gene transcription. Non-coding RNAs can target epigenetic-modifying enzymes, as well as transcription factors involved in the control of hTERT. An epigenetics diet that can affect the epigenome of cancer cells is a recent fascination that has received much attention. By combining portions of this diet with epigenome-altering treatments, it is possible to selectively regulate the epigenetic control of hTERT and its expression.

Lessons from Nature: Sources and Strategies for Developing AMPK Activators for Cancer Chemotherapeutics

Adenosine Monophosphate-Activated Protein Kinase or AMPK is a highly-conserved master-regulator of numerous cellular processes, including: Maintaining cellular-energy homeostasis, modulation of cytoskeletaldynamics, directing cell growth-rates and influencing cell-death pathways. AMPK has recently emerged as a promising molecular target in cancer therapy. In fact, AMPK deficiencies have been shown to enhance cell growth and proliferation, which is consistent with enhancement of tumorigenesis by AMPK-loss. Conversely, activation of AMPK is associated with tumor growth suppression via inhibition of the Mammalian Target of Rapamycin Complex-1 (mTORC1) or the mTOR signal pathway. The scientific communities' recognition that AMPK-activating compounds possess an anti-neoplastic effect has contributed to a rush of discoveries and developments in AMPK-activating compounds as potential anticancer-drugs. One such example is the class of compounds known as Biguanides, which include Metformin and Phenformin. The current review will showcase natural compounds and their derivatives that activate the AMPK-complex and signaling pathway. In addition, the biology and history of AMPK-signaling and AMPK-activating compounds will be overviewed, their anticancer-roles and mechanisms-of-actions will be discussed, and potential strategies for the development of novel, selective AMPK-activators with enhanced efficacy and reduced toxicity will be proposed.

Combination of erlotinib and EGCG induces apoptosis of head and neck cancers through posttranscriptional regulation of Bim and Bcl-2

Combinatorial approaches using two or more compounds are gaining increasing attention for cancer therapy. We have previously reported that the combination of the EGFR-TKI erlotinib and epigallocatechin-3-gallate (EGCG) exhibited synergistic chemopreventive effects in head and neck cancers by inducing the expression of Bim, p21, p27, and by inhibiting the phosphorylation of ERK and AKT and expression of Bcl-2. In the current study, we further investigated the mechanism of regulation of Bim, Bcl-2, p21 and p27, and their role in apoptosis. shRNA-mediated silencing of Bim significantly inhibited apoptosis induced by the combination of erlotinib and EGCG (p = 0.005). On the other hand, overexpression of Bcl-2 markedly protected cells from apoptosis (p = 0.003), whereas overexpression of constitutively active AKT only minimally protected cells from apoptosis induced by the combination of the two compounds. Analysis of mRNA expression by RT-PCR revealed that erlotinib, EGCG and their combination had no significant effects on the mRNA expression of Bim, p21, p27 or Bcl-2 suggesting the post-transcriptional regulation of these molecules. Furthermore, we found that erlotinib or the combination of EGCG and erlotinib inhibited the phosphorylation of Bim and stabilized Bim after inhibition of protein translation by cycloheximide. Taken together, our results strongly suggest that the combination of erlotinib and EGCG induces apoptosis of SCCHN cells by regulating Bim and Bcl-2 at the posttranscriptional level.

Glutamine at focus: versatile roles in cancer

During the past decade, a heightened understanding of metabolic pathways in cancer has significantly increased. It is recognized that many tumor cells are genetically programmed and have involved an abnormal metabolic state. Interestingly, this increased metabolic autonomy generates dependence on various nutrients such as glucose and glutamine. Both of these components participate in various facets of metabolic activity that allow for energy production, synthesis of biomass, antioxidant defense, and the regulation of cell signaling. Here, we outline the emerging data on glutamine metabolism and address the molecular mechanisms underlying glutamine-induced cell survival. We also discuss novel therapeutic strategies to exploit glutamine addiction of certain cancer cell lines.

Role of Polyphenols and Other Phytochemicals on Molecular Signaling

Optimized nutrition through supplementation of diet with plant derived phytochemicals has attracted significant attention to prevent the onset of many chronic diseases including cardiovascular impairments, cancer, and metabolic disorder. These phytonutrients alone or in combination with others are believed to impart beneficial effects and play pivotal role in metabolic abnormalities such as dyslipidemia, insulin resistance, hypertension, glucose intolerance, systemic inflammation, and oxidative stress. Epidemiological and preclinical studies demonstrated that fruits, vegetables, and beverages rich in carotenoids, isoflavones, phytoestrogens, and phytosterols delay the onset of atherosclerosis or act as a chemoprotective agent by interacting with the underlying pathomechanisms. Phytochemicals exert their beneficial effects either by reducing the circulating levels of cholesterol or by inhibiting lipid oxidation, while others exhibit anti-inflammatory and antiplatelet activities. Additionally, they reduce neointimal thickening by inhibiting proliferation of smooth muscle cells and also improve endothelium dependent vasorelaxation by modulating bioavailability of nitric-oxide and voltage-gated ion channels. However, detailed and profound knowledge on specific molecular targets of each phytochemical is very important to ensure safe use of these active compounds as a therapeutic agent. Thus, this paper reviews the active antioxidative, antiproliferative, anti-inflammatory, or antiangiogenesis role of various phytochemicals for prevention of chronic diseases.

The role of targeting kinase activity by natural products in cancer chemoprevention and chemotherapy (Review)

The WHO clearly identifies tumors as a curable or a chronic disease. The use of natural agents in cancer prevention and therapy is currently playing an important role. Our laboratory has been investigating various natural phenolic compounds, including grifolin, neoalbaconol and epigallocatechin-3-gallate (EGCG). In the present review, we focus on the anticancer activities and the molecular mechanisms of these compounds. Grifolin, a secondary metabolite isolated from the mushroom Albatrellus confluens, has been shown to inhibit cell growth and induce cell cycle arrest in multiple cancer cell lines by targeting extracellular signal-regulated kinase 1 or by upregulating death-associated protein kinase 1 (DAPK1) via p53. We also demonstrated that neoalbaconol, a novel small-molecular compound with a drimane-type sesquiterpenoid structure obtained from Albatrellus confluens, regulates cell metabolism by targeting 3-phosphoinositide-dependent protein kinase 1 (PDK1) and inhibits cancer cell growth. EGCG, a well known catechin found in tea, has gained much attention for its anticancer effects. Previously, we found that it regulates EBV lytic infection through the phosphoinositide-3 kinase/Akt (PI3K/Akt) and mitogen-activated protein kinase (MAPK) pathways in EBV-positive cancer cells. Therefore, these natural agents could be used as potential leading compounds in the prevention of tumor progression and/or EBV-related cancer.

Epigallocatechin-3-gallate potentiates the effect of curcumin in inducing growth inhibition and apoptosis of resistant breast cancer cells

Drug resistance remains an on-going challenge in breast cancer chemotherapy. Combination of two or more drugs is an effective strategy to access context-specific multiple targets and overcome undesirable toxicity that is almost inevitable in single-drug chemotherapy. Many plant food-derived polyphenolic compounds have been proven to modulate many key factors responsible for cancer drug resistance, which makes them a promising group of low toxicity candidates for reversing cancer resistance. In this study, we analyzed the combination effect of two chemopreventive polyphenols, curcumin (Cur) and epigallocatechin-3-gallate (EGCG), in combating resistant breast cancer. Our present results showed that EGCG significantly enhanced the growth inhibition and apoptosis in both doxorubicin (DOX)-sensitive and resistant MCF-7 cells induced by Cur. The mechanism may be related to the further activation of caspase-dependent apoptotic signaling pathways and the enhanced cellular incorporation of Cur by inhibiting P-glycoprotein (P-gp) pump function. Moreover, Cur and EGCG in combination could enhance the toxicity of DOX and increase the intracellular level of DOX in resistant MCF-7 cells. Our findings with this practical combination of Cur and EGCG encourage us to move on to a promising strategy for successful treatment of human breast cancer resistance by combining two low-toxic chemotherapeutic agents from diet.

Prevention of head and neck squamous cell carcinoma: removing the "chemo" from "chemoprevention"

The concept of chemoprevention whereby the use of a systemic agent is intended to halt the carcinogenesis process has been an attractive topic in head and neck squamous cell carcinoma (HNSCC). Yet, despite the significant efforts over the past decades and the substantial gain in knowledge of the biology of pre-malignant lesions of the head and neck, no tangible indications for chemoprevention have emerged for this disease. The negative results observed in the earlier larger studies using retinoids did not encourage further trials with these agents. Attention has been more recently focused on epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) as well as cyclo-oxygenase 2 (COX-2) inhibitors with early studies showing encouraging responses but rather poor tolerance to therapy. Natural compounds have gained more interest recently given preclinical evidence of activity as well as a low side effect profile. We herein offer a comprehensive overview of the field of chemoprevention in HNSCC with an in depth analysis of the challenges we face and discuss a road map for future directions.

Water extract from Pleurotus pulmonarius with antioxidant activity exerts in vivo chemoprophylaxis and chemosensitization for liver cancer

Chemoprophylaxis and chemosensitization are promising strategies to combat human cancers. Natural antioxidant agents show great promise in cancer therapy, and the use of edible mushrooms against cancer is receiving more interest globally. In this study, the radical scavenging activities including diphenyl-1-picrylhydrazyl, superoxide anion radical, hydroxyl radical, and hydrogen peroxide were compared among hot water extracts from 3 edible mushrooms, among which Pleurotus pulmonarius (Pp) possessed the highest antioxidant potential. Oral administration of Pp 2 wk in advance could markedly inhibit the incidence and size of tumor (Huh7 liver cancer cells) with an inhibition rate of 93.1% in nude mice. No obvious side effect was observed in the Pp-treated mice as indicated by their body weight and histological analysis of major organs. The cancer prevention by Pp treatment might be explained by the inhibition of cancer cell proliferation indicated by reduction of ki-67 staining and the inactivation of phosphoinositide 3-kinase (PI3K)/AKT signaling pathway in the Pp-treated mice. Furthermore, a significant synergistic effect was observed when the mice were treated with a combination of low dose of cisplatin and Pp. Taken together, these results suggest the potential application of Pp as an adjuvant in the chemotherapy of liver cancer.

Tea consumption and risk of head and neck cancer

Background

The current study evaluated the association between tea consumption and head and neck cancer (HNC) in Taiwan, where tea is a major agricultural product and a popular beverage.

Methods

Interviews regarding tea consumption (frequency, duration, and types) were conducted with 396 HNC cases and 413 controls. Unconditional logistic regression was performed to estimate the odds ratio (OR) and 95% confidence interval (CI) of HNC risk associated with tea drinking, adjusted for sex, age, education, cigarette smoking, betel quid chewing, and alcohol drinking.

Results

A reduced HNC risk associated with tea drinking (OR for every cup per day = 0.96, 95% CI: 0.93–0.99; OR for ≧5 cups per day = 0.60, 95% CI: 0.39–0.94) was observed. The association was especially significant for pharyngeal cancer (OR for every cup per day = 0.93, 95% CI: 0.88–0.98; OR for ≧5 cups per day = 0.32, 95% CI: 0.16–0.66). A significant inverse association between HNC and tea consumption was observed particularly for green tea.

Conclusions

This study suggests that tea drinking may reduce the risk of HNC. The anticancer property of tea, if proven, may offer a natural chemopreventive measure to reduce the occurrence of HNC.

EGCG enhances the efficacy of cisplatin by downregulating hsa-miR-98-5p in NSCLC A549 cells

In the current study, the enhanced efficacy of cisplatin caused by (-)-epigallocatechin-3-gallate (EGCG) in nonsmall cell lung cancer (NSCLC) A549 cells was observed. The tumor size was significantly smaller in vivo in the combination of cisplatin and EGCG group, as compared with cisplatin-only group. However, in NCI-H460 cells, another kind of NSCLC cells, the efficacy of cisplatin was antagonized by EGCG. MiRNA microarray showed that hsa-miR-98-5p and hsa-miR-125a-3p were differentially expressed after EGCG treatment in these 2 cell lines. After transfection of hsa-miR-98-5p inhibitor, the survival fraction of both A549 and NCI-H460 cells was decreased upon cisplatin treatment. Meanwhile, as a critical regulator in the cisplatin-induced apoptosis, p53 was elevated by silencing of hsa-miR-98-5p. These results suggested that EGCG inhibited the expression of hsa-miR-98-5p, followed by an increase of p53, thus the efficacy of cisplatin was enhanced. Bioinformatics analysis showed that hsa-miR-125a-3p might have a strong connection with classical MAPK pathway. Taken together, these findings indicate that hsa-miR-98-5p could be a potential target in clinical cisplatin treatment of NSCLC. The combination of EGCG and cisplatin might be an effective therapeutic strategy in treating some type of NSCLC, although the possibility of antagonistic interactions must also be taken into account.

The effect of epigallocatechin-3-gallate (EGCG) on human alveolar bone cells both in vitro and in vivo

OBJECTIVE

The effects of epigallocatechin-3-gallate (EGCG), a major catechin in green tea, on human and mouse osteoblasts remain controversial. This study investigated the direct effects of EGCG on human alveolar bone-derived cells (hABCs) both in vitro and in vivo.

DESIGN

hABCs which were collected from eight children (aged 7-9 years, seven males and one female) were treated with EGCG at various concentrations (1, 5, 10, 25, and 50μM), and a proliferation assay, flow cytometric analysis for apoptosis evaluation, migration assay, and in vitro osteogenic differentiation were performed. hABCs that were pretreated with 10μM EGCG and mixed with calcium phosphate carrier combined with EGCG (0.1, 0.5, or 1.5mg) in vivo were transplanted into immunodeficient mouse. Histological staining, quantitative gene expressions, and alkaline phosphatase activity were evaluated in the retrieved transplants.

RESULTS

The proliferation and migration were decreased when EGCG was present at over 25μM. The osteogenic differentiation increased slightly when EGCG was present at up to 10μM, and clearly decreased for higher concentrations of EGCG. In vivo, the potential for hard-tissue formation was slightly higher for the group with 0.1mg of EGCG than for the control group, and decreased sharply for higher concentrations of EGCG.

CONCLUSION

The present observations suggest that EGCG at a low concentration can slightly enhance the osteogenic effect in vivo, whereas at a higher concentration it can prevent the osteogenic differentiation of hABCs both in vitro and in vivo.

Dietary epigenetics in cancer and aging

Although epigenetic aberrations frequently occur in aging and cancer and form a core component of these conditions, perhaps the most useful aspect of epigenetic processes is that they are readily reversible. Unlike genetic effects that also play a role in cancer and aging, epigenetic aberrations can be relatively easily corrected. One of the most widespread approaches to the epigenetic alterations in cancer and aging is dietary control. This can be achieved not only through the quality of the diet, but also through the quantity of calories that are consumed. Many phytochemicals such as sulforaphane from cruciferous vegetables and green tea have anticancer epigenetic effects and are also efficacious for preventing or treating the epigenetic aberrations of other age-associated diseases besides cancer. Likewise, the quantity of calories that are consumed has proven to be advantageous in preventing cancer and extending the lifespan through control of epigenetic mediators. The purpose of this chapter is to review some of the most recent advances in the epigenetics of cancer and aging and to provide insights into advances being made with respect to dietary intervention into these biological processes that have vast health implications and high translational potential.

Chemoprevention of head and neck cancer with celecoxib and erlotinib: results of a phase ib and pharmacokinetic study

Epidermal growth factor receptor (EGFR) and COX-2 inhibitors synergistically inhibit head and neck squamous cell carcinoma tumorigenesis in preclinical studies. We conducted a phase I and pharmacokinetic study with the erlotinib and celecoxib combination in patients with advanced premalignant lesions. Thirty-six subjects with oral leukoplakia, mild, moderate, or severe dysplasia, or carcinoma in situ were screened for study participation; 12 consented and received therapy for a median of 5.38 months. Erlotinib was escalated following a standard 3+3 design at 50, 75, and 100 mg orally daily and celecoxib was fixed at 400 mg twice daily for 6 months. Biopsy of lesions and cytobrush of normal mucosa were performed at baseline, 3, 6, and 12 months. Erlotinib pharmacokinetics were analyzed in 10 subjects. The maximum tolerated dose of erlotinib with celecoxib 400 mg BID was 50 mg per day with skin rash being the main observed toxicity. Overall histologic response rate was 63% (complete response, 43%; partial response, 14%; stable disease, 29%; and disease progression, 14%). With median follow-up of 36 months, mean time to progression to higher-grade dysplasia or carcinoma was 25.4 months. Downregulation of EGFR and p-ERK in follow-up biopsies correlated with response to treatment. Larger average erlotinib V/F (approximately 308 L) and CL/F (8.3 L/h) compared with previous studies may be related to relatively large average bodyweights. Average erlotinib t1/2 was 25.6 hours. Encouraging responses to the celecoxib and erlotinib combination correlated with EGFR pathway inhibition. Although erlotinib-related rash was the main limitation to dose escalation, the intervention was well tolerated.

Delivering flavonoids into solid tumors using nanotechnologies

INTRODUCTION

Long-term epidemiological studies have demonstrated that regular ingestion of flavonoids contained in dietary sources is associated with a reduced risk for many chronic diseases including cancer. However, although flavonoids are largely consumed in the diet and high concentrations may exist in the intestine after oral administration, the plasma/tissue concentrations of flavonoids are lower than their effective therapeutic doses due to poor bioavailability, resulting in the limited efficacy of flavonoids in various clinical studies. Therefore, the application of nanotechnology to deliver flavonoids to tumor sites has received considerable attention in recent years.

AREAS COVERED

In this review, after a general review of the potential benefits of flavonoids in cancer therapy and several key factors affecting their bioavailability, the current efforts in improving the delivery efficacy of promising candidates that are particularly important in the human diet, namely quercetin, epigallocatechin-3-gallate (EGCG) and genistein were focused on. Finally, the challenges of developing flavonoid delivery systems that improve flavonoid bioavailability and their anticancer therapy potentials were summarized.

EXPERT OPINION

The design of suitable molecular carriers for flavonoids is an area of research that is in rapid progress. A large number of unheeded promising favonoids are suffering from poor in vivo parameters, their potential benefits deserves further research. Furthermore, more effort should be placed on developing active targeting systems, evaluating the efficacy and toxicity of novel flavonoid delivery systems through small and large scale clinical trials.

Chemopreventive potential of flavonoids in oral squamous cell carcinoma in human studies

Evidence available from nutritional epidemiology has indicated an inverse association between regular consumption of fruits and vegetables and the risk of developing certain types of cancer. In turn, preclinical studies have attributed the health-promoting effects of plant foods to some groups of phytochemicals, by virtue of their many biological activities. In this survey, we briefly examine the chemopreventive potential of flavonoids and flavonoid-rich foods in human oral carcinogenesis. Despite the paucity of data from clinical trials and epidemiological studies, in comparison to in vitro/in vivo investigations, a high level of evidence has been reported for epigallocatechin gallate (EGCG) and anthocyanins. These flavonoids, abundant in green tea and black raspberries, respectively, represent promising chemopreventive agents in human oral cancer.

Combination of low concentration of (-)-epigallocatechin gallate (EGCG) and curcumin strongly suppresses the growth of non-small cell lung cancer in vitro and in vivo through causing cell cycle arrest

(−)-Epigallocatechin gallate (EGCG) and curcumin are two naturally derived agents that have been widely investigated worldwide. They exhibit their anti-tumor effects in many types of cancers. In the current study, the effect of the combination of the two agents on non-small cell lung cancer (NSCLC) cells was investigated. The results revealed that at low concentrations, the combination of the EGCG and curcumin strongly enhanced cell cycle arrest. Flow cytometry analysis showed that the cells were arrested at G1 and S/G2 phases. Two main cell cycle related proteins cyclin D1 and cyclin B1 were significantly inhibited at the present of EGCG and curcumin. EdU (5-ethynyl-2′-deoxyuridine) fluorescence staining showed that the DNA replication was significantly blocked. A clonal growth assay also confirmed a marked repression of cell growth. In a lung cancer xenograft node mice model, combination of EGCG and curcumin exhibited protective effect against weight loss due to tumor burden. Tumor growth was strongly repressed by the combination of the two agents, without causing any serious side-effect. Overall, these results strongly suggest that EGCG in combination with curcumin could be a candidate for chemoprevention agent of NSCLC.

Oral premalignancy: the roles of early detection and chemoprevention

Premalignancy and chemoprevention studies in head and neck cancer typically focus on the oral cavity. Avoiding or cessation of alcohol and smoking, early detection of potentially malignant disorders or cancer, and early detection of recurrent and/or second primary tumor form the basis of prevention of oral cancer. Analysis of tissue prospectively collected in evaluation of retinoids for chemoprevention trials allowed identification of molecular biomarkers of risk to develop oral cancer, loss of heterozygosity being the most validated one. Improving risk assessment and identification of new targets for chemoprevention represent the main challenges in this field.

Phytochemicals as chemosensitizers: from molecular mechanism to clinical significance

This review provides an overview of the clinical relevance of chemosensitization, giving special reference to the phenolic phytochemicals, curcumin, genistein, epigallocatechin gallate, quercetin, emodin, and resveratrol, which are potential candidates due to their ability to regulate multiple survival pathways without inducing toxicity. We also give a brief summary of all the clinical trials related to the important phytochemicals that emerge as chemosensitizers. The mode of action of these phytochemicals in regulating the key players of the death receptor pathway and multidrug resistance proteins is also abridged. Rigorous efforts in identifying novel chemosensitizers and unraveling their molecular mechanism have resulted in some of the promising candidates such as curcumin, genistein, and polyphenon E, which have gone into clinical trials. Even though considerable research has been conducted in identifying the salient molecular players either contributing to drug efflux or inhibiting DNA repair and apoptosis, both of which ultimately lead to the development of chemoresistance, the interdependence of the molecular pathways leading to chemoresistance is still the impeding factor in the success of chemotherapy. Even though clinical trials are going on to evaluate the chemosensitizing efficacy of phytochemicals such as curcumin, genistein, and polyphenon E, recent results indicate that more intense study is required to confirm their clinical efficacy. Current reports also warrant intense investigation about the use of more phytochemicals such as quercetin, emodin, and resveratrol as chemosensitizers, as all of them have been shown to modulate one or more of the key regulators of chemoresistance.

Epigenetic modifications by dietary phytochemicals: implications for personalized nutrition

In the last two decades, the study of epigenetic modification emerged as one of the major areas of cancer treatment targeted by dietary phytochemicals. Recent studies with various types of cancers revealed that the epigenetic modifications are associated with the food source corresponds to dietary phytochemicals. The dietary phytochemicals have been used in Asian countries for thousands of years to cure several diseases including cancer. They have been reported to modulate the several biological processes including histone modification, DNA methylation and non-coding microRNA expression. These events play a vital role in carcinogenesis. Various studies suggest that a number of dietary compounds present in vegetables, spices and other herbal products have epigenetic targets in cancer cells. Dietary phytochemicals have been reported to repair DNA damage by enhancing histone acetylation that helps to restrain cell death, and also alter DNA methylation. These phytochemicals are able to modulate epigenetic modifications and their targets to cure several cancers. Epigenetic aberrations dynamically contribute to cancer pathogenesis. Given the individualized traits of epigenetic biomarkers, the personalized nutrition will help us to prevent various types of cancer. In this review, we will discuss the effect of dietary phytochemicals on genetic and epigenetic modifications and how these modifications help to prevent various types of cancers and improve health outcomes.

Going Green: The Role of the Green Tea Component EGCG in Chemoprevention

Tea is one of the most consumed beverages worldwide, and green tea is the least processed from the buds of the Camellia sinensis plant. The most abundant component of green tea is (-)-epigallocatechin-3-gallate (EGCG), which has been the focus of many cell culture, animal and clinical trials, revealing that EGCG possesses antiproliferative, antimutagenic, antioxidant, antibacterial, antiviral and chemopreventive effects. In this review we briefly summarize the mechanism of action(s) of the green tea component EGCG, highlighting recent advances in the epigenetic regulation by EGCG. Additionally, we provide an overview of mouse chemoprevention studies and EGCG chemoprevention clinical trials.

Incidence of second primary malignancies in patients with treated head and neck cancer: a comprehensive review of literature

BACKGROUND

Increased incidence of a second primary aero-digestive malignancy after an index head and neck cancer (HNC) is well-documented. Furthermore, a clear set of surveillance strategies for second primary aero-digestive cancers in these patients exists.

METHODS

The goal of this article is to review the published literature on risk of second primary malignancies (SPMs) (including aero-digestive malignancies) after a treated index HNC as well as its associated predictors, prognosis and surveillance. Most relevant publications were identified through searching the PubMed database for articles published up to July 2012; epidemiologic evidence was synthesized and thoroughly analyzed.

FINDINGS

Data from randomized controlled trials, meta-analyses, population-based and cohort group studies, prior reviews, and case reports indicate an increased incidence of various SPMs after occurrence of a HNC. These cancers are not limited to upper aero-digestive sites. Common risk factors including environmental, genetic and immune factors may explain the increased incidence of second cancers in this patient population. In addition, site of the index HNC may predict the site of a future SPM.

CONCLUSIONS

As a general rule, oral cavity and oropharyngeal squamous cell cancers are associated more with head and neck region SPM, while laryngeal and hypopharyngeal cancers - with that of the lung. As these cancers confer dismal prognosis and shorter survival in patients with HNCs, several literature sources recommend close surveillance for and an aggressive therapy of SPM. Notwithstanding, their optimal management and follow-up schedule remains to be established.

Plants vs. cancer: a review on natural phytochemicals in preventing and treating cancers and their druggability

Cancer remains to be one of the leading causes of death in the United States and around the world. The advent of modern drug-targeted therapies has undeniably improved cancer patients' cares. However, advanced metastasized cancer remains untreatable. Hence, continued searching for a safer and more effective chemoprevention and treatment is clearly needed for the improvement of the efficiency and to lower the treatment cost for cancer care. Cancer chemoprevention with natural phytochemical compounds is an emerging strategy to prevent, impede, delay, or cure cancer. This review summarizes the latest research in cancer chemoprevention and treatment using the bioactive components from natural plants. Relevant molecular mechanisms involved in the pharmacological effects of these phytochemicals are discussed. Pharmaceutical developmental challenges and opportunities in bringing the phytochemicals into the market are also explored. The authors wish to expand this research area not only for their scientific soundness, but also for their potential druggability.

(-)-Epigallocatechin-3-gallate inhibition of Epstein-Barr virus spontaneous lytic infection involves ERK1/2 and PI3-K/Akt signaling in EBV-positive cells

Epstein-Barr virus (EBV) reactivation into the lytic cycle plays certain roles in the development of EBV-associated diseases, including nasopharyngeal carcinoma and lymphoma. In this study, we investigated the effects of the tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) on EBV spontaneous lytic infection and the mechanism(s) involved in EBV-positive cells. We found that EGCG could effectively inhibit the constitutive lytic infection of EBV at the DNA, gene transcription and protein levels by decreasing the phosphorylation and activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt. By using cellular signaling pathway-specific inhibitors, we also explored the signaling mechanisms underlying the inhibitory effects of EGCG on EBV spontaneous lytic infection in cell models. Results show that specific inhibitors of Mitogen-Activated Protein Kinase Kinase (MEK) (PD98059) and phosphatidylinositol 3-kinase [PI3-K (LY294002)] markedly downregulated gene transcription and expression of BZLF1 and BMRF1 indicating that the MEK/ERK1/2 and PI3-K/Akt pathways are involved in the EBV spontaneous lytic cycle cascade. Therefore, one of the mechanisms by which EGCG inhibits EBV spontaneous lytic infection appears to involve the suppression of the activation of MEK/ERK1/2 and PI3-K/Akt signaling.