Molecular targets for cancer chemoprevention

Oral Pre-malignancy: An Update on Novel Therapeutic Approaches

PURPOSE OF REVIEW

This review aims to provide a comprehensive overview of the current advances in managing and preventing progression of oral potentially malignant disorders (OPMDs), focusing on their histological and clinicopathological features, and management.

RECENT FINDINGS

Recent studies, including a multicenter cross-sectional study, have identified oral leukoplakia as the most prevalent form of OPMD, comprising over half of the cases examined. Advances in histological grading, specifically the World Health Organization's three-tier system (mild, moderate, and severe dysplasia), have significantly enhanced the accuracy of risk assessment for malignant transformation. Additionally, treatments such as surgical interventions, photodynamic therapy, and chemopreventive and molecularly targeted agents are being evaluated for their safety and efficacy as well as, immune checkpoint inhibitors being evaluated as potential preventive strategies to halt the progression of OPMDs. The management of OPMDs remains challenging due to the lack of standardized screening protocols and varied clinical management approaches. Despite this, recent advancements in diagnostic grading and therapeutic interventions provide a framework for improved treatment outcomes. Continued research into the molecular and cellular mechanisms driving development and progression of OPMDs and innovative treatment trials are essential to optimize strategies that prevent malignant progression and thereby reduce the global health burden of oral cancer.

Reassessing the role of phytochemicals in cancer chemoprevention

In this comprehensive review we tried to reassess the role of phytochemicals in cancer chemoprevention. The exploration of the "synergistic effect" concept, advocating combined chemopreventive agents, faces challenges like low bioavailability. The review incorporates personal, occasionally controversial, viewpoints on natural compounds' cancer preventive capabilities, delving into mechanisms. Prioritizing significant contributions within the vast research domain, we aim stimulating discussion to provide a comprehensive insight into the evolving role of phytochemicals in cancer prevention. While early years downplayed the role of phytochemicals, the late nineties witnessed a shift, with leaders exploring their potential alongside synthetic compounds. Challenges faced by chemoprevention, such as limited pharmaceutical interest and cost-effectiveness issues, persist despite successful drugs. Recent studies, including the EPIC study, provide nuanced insights, indicating a modest risk reduction for increased fruit and vegetable intake. Phytochemicals, once attributed to antioxidant effects, face scrutiny due to low bioavailability and conflicting evidence. The Nrf2-EpRE signaling pathway and microbiota-mediated metabolism emerge as potential mechanisms, highlighting the complexity of understanding phytochemical mechanisms in cancer chemoprevention.

Comprehensive DNA Methylation Analysis Indicates That Pancreatic Intraepithelial Neoplasia Lesions Are Acinar-Derived and Epigenetically Primed for Carcinogenesis

Pancreatic ductal adenocarcinoma (PDAC) is believed to arise from the accumulation of a series of somatic mutations and is also frequently associated with pancreatic intraepithelial neoplasia (PanIN) lesions. However, there is still debate as to whether the cell type-of-origin of PanINs and PDACs in humans is acinar or ductal. As cell type identity is maintained epigenetically, DNA methylation changes during pancreatic neoplasia can provide a compelling perspective to examine this question. Here, we performed laser-capture microdissection on surgically resected specimens from 18 patients to isolate, with high purity, DNA for whole-genome bisulfite sequencing from four relevant cell types: acini, nonneoplastic ducts, PanIN lesions, and PDAC lesions. Differentially methylated regions (DMR) were identified using two complementary analytical approaches: bsseq, which identifies any DMRs but is particularly useful for large block-like DMRs, and informME, which profiles the potential energy landscape across the genome and is particularly useful for identifying differential methylation entropy. Both global methylation profiles and block DMRs clearly implicated an acinar origin for PanINs. At the gene level, PanIN lesions exhibited an intermediate acinar-ductal phenotype resembling acinar-to-ductal metaplasia. In 97.6% of PanIN-specific DMRs, PanIN lesions had an intermediate methylation level between normal and PDAC, which suggests from an information theory perspective that PanIN lesions are epigenetically primed to progress to PDAC. Thus, epigenomic analysis complements histopathology to define molecular progression toward PDAC. The shared epigenetic lineage between PanIN and PDAC lesions could provide an opportunity for prevention by targeting aberrantly methylated progression-related genes.

SIGNIFICANCE

Analysis of DNA methylation landscapes provides insights into the cell-of-origin of PanIN lesions, clarifies the role of PanIN lesions as metaplastic precursors to human PDAC, and suggests potential targets for chemoprevention.

Chemoprevention of oral cancer: A review and future perspectives

BACKGROUND

Oral cancer causes significant morbidity and mortality. Chemoprevention utilizes medication or natural compounds to reverse oral premalignant lesions and to prevent second primary tumors.

METHODS

A comprehensive PubMed database and Cochrane Library search from 1980 to 2021 was performed using the keywords "leukoplakia," "oral premalignant lesion," and "chemoprevention."

RESULTS

Chemopreventive agents included retinoids, carotenoids, cyclooxygenase inhibitor, herbal extracts, bleomycin, tyrosine kinase inhibitors, metformin, and immune checkpoint inhibitors. Although some agents demonstrated effect in reducing premalignant lesions and preventing second primary tumors, the results among different studies were highly variable.

CONCLUSIONS

The results of different trials, albeit inconsistent, provided substantial information for future studies. In the era of personalized medicine, future studies will focus on identifying specific biomarkers and molecular profile to monitor and to prevent malignant transformation. Larger trials are warranted to validate the effect of chemopreventive agents.

Precise Subcellular Organelle Targeting for Boosting Endogenous-Stimuli-Mediated Tumor Therapy

Though numerous external-stimuli-triggered tumor therapies, including phototherapy, radiotherapy, and sonodynamic therapy have made great progress in cancer therapy, the low penetration depth of the laser, safety concerns of radiation, the therapeutic resistance, and the spatio-temporal constraints of the specific equipment restrict their convenient clinical applications. What is more, the inherent physiological barriers of the tumor microenvironment (TME), including hypoxia, heterogeneity, and high expression of antioxidant molecules also restrict the efficiency of tumor therapy. As a result, the development of nanoplatforms responsive to endogenous stimuli (such as glucose, acidic pH, cellular redox events, and etc.) has attracted great attention for starvation therapy, ion therapy, prodrug-mediated chemotherapy, or enzyme-catalyzed therapy. In addition, nanomedicines can be modified by some targeted units for precisely locating in subcellular organelles and boosting the destroying of tumor tissue, decreasing the dosage of nanoagents, reducing side effects, and enhancing the therapeutic efficiency. Herein, the properties of the TME, the advantages of endogenous stimuli, and the principles of subcellular-organelle-targeted strategies will be emphasized. Some necessary considerations for the exploitation of precision medicine and clinical translation of multifunctional nanomedicines in the future are also pointed out.

Recent Updates on Marine Cancer-Preventive Compounds

The natural compounds derived from marine organisms often exhibit unique chemical structures and potent biological activities. Cancer-preventive activity is one of the rather new activities that has emerged and been extensively studied over the last decades. This review summarizes the recent updates on the marine chemopreventive compounds covering the relevant literature published in 2013-2021 and following the previous comprehensive review by Stonik and Fedorov (Marine Drugs 2014, 12, 636-671). In the current article, only the molecules having an effect on malignant transformation (or related pathway and molecules), cancer stem cells, or carcinogen-induced in vivo tumor development were considered to be "true" cancer-preventive compounds and were, therefore, reviewed. Additionally, particular attention has been given to the molecular mechanisms of chemoprevention, executed by the reported marine compounds.

Factors of sexual quality of life in gynaecological cancers: a systematic literature review

Background

The impact of cancer diagnosis and treatment on sexual quality of life (SQoL) is a well-established survivorship issue for gynaecological cancer survivors (GCS), yet little is known on how to intervene.

Purpose

The aim of this systematic review was to identify the factors explaining the variability in SQoL for GCS.

Methods

We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework and the software Covidence. Electronic databases Scopus, Web of Science, PUBMED and CINAHL were searched for original research on GCS published between 2002 and 2018. We performed a two-stage screening process against selection criteria and quality assessment of individual studies. The Salutogenic Theory and the PRECEDE–PROCEED model were used as theoretical frameworks to identify and categorise factors.

Results

The initial search yielded 3,505 articles resulting in a total of 46 studies used to examine the association between factors of SQoL and gynaecological cancers. Our findings suggested that SQoL varies across subgroups based on age, menopausal status, relationship status, and treatment modality. Protective factors included clinicians’ knowledge and confidence, preventive medical approach, risk and needs assessment, patient–clinician communication, relationship quality, psychosocial support, symptom management, accessibility of psychosexual care, and self-efficacy in the rediscovery of sexuality.

Conclusion

Despite the high incidence and long-term impact of sexual health issues on quality of life, supportive care needs are not being met. A better understanding of the evidence base around the factors of SQoL can help health professionals take steps to protect and improve SQoL in GCS.

Non-Steroidal Anti-Inflammatory Drugs in Colorectal Cancer Chemoprevention

Simple Summary

There is growing evidence from epidemiologic, preclinical and clinical studies suggesting that non-steroidal anti-inflammatory drugs (NSAIDs) play a beneficial role in colorectal cancer chemoprevention. They reduce the risk of colorectal polyps, mostly by cyclooxygenase-2 inhibition. The aim of our work was to describe the current state of scientific knowledge on the potential added value of the use of NSAIDs (such as aspirin, sulindac, and celecoxib) as chemopreventive agents in patients at risk of colorectal cancer. The study confirmed that there is a link between the long-term use of the NSAIDs and a decrease in the risk of colorectal cancer.

Abstract

Since colorectal cancer is one of the world’s most common cancers, studies on its prevention and early diagnosis are an emerging area of clinical oncology these days. For this study, a review of randomized controlled, double-blind clinical trials of selected NSAIDs (aspirin, sulindac and celecoxib) in chemoprevention of colorectal cancer was conducted. The main molecular anticancer activity of NSAIDs is thought to be a suppression of prostaglandin E₂ synthesis via cyclooxygenase-2 inhibition, which causes a decrease in tumor cell proliferation, angiogenesis, and increases apoptosis. The lower incidence of colorectal cancer in the NSAID patients suggests the long-lasting chemopreventive effect of drugs studied. This new approach to therapy of colorectal cancer may transform the disease from a terminal to a chronic one that can be taken under control.

Chemopreventive Potential of Caryophyllane Sesquiterpenes: An Overview of Preliminary Evidence

Chemoprevention is referred to as a strategy to inhibit, suppress, or reverse tumor development and progression in healthy people along with high-risk subjects and oncologic patients through using pharmacological or natural substances. Numerous phytochemicals have been widely described in the literature to possess chemopreventive properties, although their clinical usefulness remains to be defined. Among them, caryophyllane sesquiterpenes are natural compounds widely occurring in nature kingdoms, especially in plants, fungi, and marine environments. Several structures, characterized by a common caryophyllane skeleton with further rearrangements, have been identified, but those isolated from plant essential oils, including β-caryophyllene, β-caryophyllene oxide, α-humulene, and isocaryophyllene, have attracted the greatest pharmacological attention. Emerging evidence has outlined a complex polypharmacological profile of caryophyllane sesquiterpenes characterized by blocking, suppressing, chemosensitizing, and cytoprotective properties, which suggests a possible usefulness of these natural substances in cancer chemoprevention for both preventive and adjuvant purposes. In the present review, the scientific knowledge about the chemopreventive properties of caryophyllane sesquiterpenes and the mechanisms involved have been collected and discussed; moreover, possible structure-activity relationships have been highlighted. Although further high-quality studies are required, the promising preclinical findings and the safe pharmacological profile encourage further studies to define a clinical usefulness of caryophyllane sesquiterpenes in primary, secondary, or tertiary chemoprevention.

The study of EGFR-ligand complex electron property relationship with biological activity

The present investigation grounded on estimation of electron properties of the structures of EGFR proteins-ligand complexes using our laboratory-developed methodology AlteQ approach, which describes the molecular electron density of the complex in space for a certain point in three-dimensional coordinates. Briefly, the system embodies molecular electron density as a sum of Slater's type atomic increments of the molecular system. Further, using this methodology, we calculated different electron characteristics of selected EGFR protein-ligand complexes and established the relationship between different electron properties with their experimental pharmacological activity value (pIC₅₀). The study suggested that EGFR inhibitory activity has higher correlation with intermolecular contacts of H with pi-system of aromatic ring between protein and ligands. Therefore, this created model has impact to identify and design potential ligands against EGFR in anticancer drug discovery.Communicated by Ramaswamy H. Sarma.

Metabolomics Analysis of Aspirin's Effects in Human Colon Tissue and Associations with Adenoma Risk

Although substantial evidence supports aspirin's efficacy in colorectal cancer chemoprevention, key molecular mechanisms are uncertain. An untargeted metabolomics approach with high-resolution mass spectrometry was used to elucidate metabolic effects of aspirin treatment in human colon tissue. We measured 10,269 metabolic features in normal mucosal biopsies collected at colonoscopy after approximately 3 years of randomized treatment with placebo, 81 or 325 mg/day aspirin from 325 participants in the Aspirin/Folate Polyp Prevention Study. Linear regression was used to identify aspirin-associated metabolic features and network analysis was used to identify pathways and predict metabolite identities. Poisson regression was used to examine metabolic features associations with colorectal adenoma risk. We detected 471 aspirin-associated metabolic features. Aside from the carnitine shuttle, aspirin-associated metabolic pathways were largely distinct for 81 mg aspirin (e.g., pyrimidine metabolism) and 325 mg (e.g., arachidonic acid metabolism). Among aspirin-associated metabolic features, we discovered three that were associated with adenoma risk and could contribute to the chemopreventive effect of aspirin treatment, and which have also previously been associated with colorectal cancer: creatinine, glycerol 3-phosphate, and linoleate. The last two of these are in the glycerophospholipid metabolism pathway, which was associated with 81 mg aspirin treatment and provides precursors for the synthesis of eicosanoids from arachidonic acid upstream of cyclooxygenase inhibition by aspirin. Conversely, carnitine shuttle metabolites were increased with aspirin treatment and associated with increased adenoma risk. Thus, our untargeted metabolomics approach has identified novel metabolites and pathways that may underlie the effects of aspirin during early colorectal carcinogenesis.

Licochalcone A reverses NNK-induced ectopic miRNA expression to elicit in vitro and in vivo chemopreventive effects

BACKGROUND

Chemoprevention is the best cost-effective way regarding cancers. MicroRNAs (miRNAs) have been reported to be differentially expressed during the development of lung cancer. However, if lung cancer prevention can be achieved through modulating miRNAs expression so far remains unknown.

PURPOSE

To discover ectopically expressed miRNAs in NNK-induced lung cancer and clarify whether Licochalcone A (lico A) can prevent NNK-induced lung cancer by modulating miRNA expression.

STUDY DESIGN AND METHODS

A/J mice were used to construct a lung cancer model by intraperitoneal injection with physiological saline NNK (100 mg/kg). Chemopreventive effects of lico A against lung cancer at 2 mg/kg and 20 mg/kg doses were evaluated in vivo. MicroRNA array and RT-qPCR were used to assess the expression levels of miRNAs. MLE-12 cells were treated with 0.1 mg/ml NNK, stimulating the ectopic expression pattern of miR-144-3p, miR-20a-5p, miR-29c-3p, let-7d-3p, and miR-328-3p. miR-144-3p mimics and inhibitors were used to manipulate miR-144-3p levels. The effects of lico A (10 μM) on cell cycle distribution, apoptosis, and the expression of CK19, RASA1, miR-144-3p, miR-20a-5p, miR-29c-3p, let-7d-3p, and miR-328-3p in NNK-treated MLE-12 cells were studied.

RESULTS

The expression levels of miR-144-3p, miR-20a-5p, and miR-29c-3p increased, while those of let-7d-3p and miR-328-3p decreased in both NNK-induced A/J mice and MLE-12 cells. Lico A could reverse the NNK-induced ectopic miRNA (miR-144-3p, miR-20a-5p, miR-29c-3p, let-7d-3p, and miR-328-3p) expression both in vivo and in vitro and elicit in vivo lung cancer chemopreventive effect against NNK. In MLE-12 cells, the overexpression of miR-144-3p elicited the same effect as NNK regarding the expression of lung cancer biomarker CK19; the silencing of miR-144-3p reversed the effect of NNK on cell cycle distribution and apoptosis. Lico A could reverse the effect of NNK on the expression of miR-144-3p, CK19, and RASA1 (predicted target of miR-144-3p).

CONCLUSION

The present study suggests that miR-144-3p, miR-20a-5p, miR-29c-3p, let-7d-3p, and miR-328-3p were involved in the in vivo pathogenesis of NNK-induced lung cancer, and lico A could reverse the effect of NNK both in vivo and in vitro to elicit lung cancer chemopreventive effects through, at least partially, these five ectopically expressed miRNAs, especially miR-144-3p.

Investigating Programmed Cell Death and Tumor Invasion in a Three-Dimensional (3D) Microfluidic Model of Glioblastoma

Glioblastoma multiforme (GBM) is a rapidly progressive and deadly form of brain tumor with a median survival rate of ~15 months. GBMs are hard to treat and significantly affect the patient's physical and cognitive abilities and quality of life. Temozolomide (TMZ)-an alkylating agent that causes DNA damage-is the only chemotherapy choice for the treatment of GBM. However, TMZ also induces autophagy and causes tumor cell resistance and thus fails to improve the survival rate among patients. Here, we studied the drug-induced programmed cell death and invasion inhibition capacity of TMZ and a mevalonate cascade inhibitor, simvastatin (Simva), in a three-dimensional (3D) microfluidic model of GBM. We elucidate the role of autophagy in apoptotic cell death by comparing apoptosis in autophagy knockdown cells (Atg7 KD) against their scrambled counterparts. Our results show that the cells were significantly less sensitive to drugs in the 3D model as compared to monolayer culture systems. An immunofluorescence analysis confirmed that apoptosis is the mechanism of cell death in TMZ- and Simva-treated glioma cells. However, the induction of apoptosis in the 3D model is significantly lower than in monolayer cultures. We have also shown that autophagy inhibition (Atg7 KD) did not change TMZ and Simva-induced apoptosis in the 3D microfluidic model. Overall, for the first time in this study we have established the simultaneous detection of drug induced apoptosis and autophagy in a 3D microfluidic model of GBM. Our study presents a potential ex vivo platform for developing novel therapeutic strategies tailored toward disrupting key molecular pathways involved in programmed cell death and tumor invasion in glioblastoma.

Repurposing of plant alkaloids for cancer therapy: Pharmacology and toxicology

Drug repurposing (or repositioning) is an emerging concept to use old drugs for new treatment indications. Phytochemicals isolated from medicinal plants have been largely neglected in this context, although their pharmacological activities have been well investigated in the past, and they may have considerable potentials for repositioning. A grand number of plant alkaloids inhibit syngeneic or xenograft tumor growth in vivo. Molecular modes of action in cancer cells include induction of cell cycle arrest, intrinsic and extrinsic apoptosis, autophagy, inhibition of angiogenesis and glycolysis, stress and anti-inflammatory responses, regulation of immune functions, cellular differentiation, and inhibition of invasion and metastasis. Numerous underlying signaling processes are affected by plant alkaloids. Furthermore, plant alkaloids suppress carcinogenesis, indicating chemopreventive properties. Some plant alkaloids reveal toxicities such as hepato-, nephro- or genotoxicity, which disqualifies them for repositioning purposes. Others even protect from hepatotoxicity or cardiotoxicity of xenobiotics and established anticancer drugs. The present survey of the published literature clearly demonstrates that plant alkaloids have the potential for repositioning in cancer therapy. Exploitation of the chemical diversity of natural alkaloids may enrich the candidate pool of compounds for cancer chemotherapy and -prevention. Their further preclinical and clinical development should follow the same stringent rules as for any other synthetic drug as well. Prospective randomized, placebo-controlled clinical phase I and II trials should be initiated to unravel the full potential of plant alkaloids for drug repositioning.

A Gold Nanocage/Cluster Hybrid Structure for Whole-Body Multispectral Optoacoustic Tomography Imaging, EGFR Inhibitor Delivery, and Photothermal Therapy

Gold nanocages (AuNCs) and gold nanoclusters (AuClusters) are two classes of advantageous nanostructures with special optical properties, and many other attractive properties. Integrating them into one nanosystem may achieve greater and smarter performance. Herein, a hybrid gold nanostructure for fluorescent and optoacoustic tomography imaging, controlled release of drugs, and photothermal therapy (PTT) is demonstrated. For this nanodrug (EA-AB), an epidermal growth factor receptor (EGFR) inhibitor erlotinib (EB) is loaded into AuNCs, which are then capped and functionalized by biocompatible AuCluster@BSA (BSA = bovine serum albumin) conjugates via electrostatic interaction. Upon cell internalization, the lysosomal proteases and low pH cause the release of EB from EA-AB, and also induce fluorescence restoration of the AuCluster for imaging. Irradiation with near-infrared light further promotes the drug release and affords a PTT effect as well. The AuNC-based nanodrug is optoacoustically active, and its biodistribution and metabolic process have been successfully monitored by whole-body and 3D multispectral optoacoustic tomography imaging. Owing to the combined actions of PTT and EGFR pathway blockage, EA-AB exhibits marked tumor inhibition efficacy in vivo.

Ubiquitin ligase TRIM65 promotes colorectal cancer metastasis by targeting ARHGAP35 for protein degradation

Tripartite motif-containing protein 65 (TRIM65) is an E3 ubiquitin ligase and a critical regulator of a variety of cellular processes as well as tumor progression. Therefore, more substrates must be identified in the physiology or disease context. Here, we found that TRIM65 is upregulated and associated with poor survival in colorectal cancer (CRC). More specifically, high expression of TRIM65 is associated with CRC metastasis and recurrence. Ectopic overexpression of TRIM65 in CRC cell lines enhanced proliferation, invasion, and migration, while knockdown of TRIM65 expression had the opposite effects. Furthermore, we identified a new substrate of TRIM65, namely ARHGAP35, a Rho GTPase-activating protein (GAP) that is involved in polarized cell migration. Phenotypically, forced expression of TRIM65 induces increased production of migration-related structures, focal adhesions, and/or filopodia and enhances CRC metastasis to the liver or the lung in a mouse model. Mechanistic studies revealed that TRIM65 mediates ubiquitination of ARHGAP35, whose degradation leads to elevated Rho GTPase activity. In addition, we identified several phosphorylation sites on TRIM65. In sum, we reveal a novel TRIM65-GAP-Rho regulatory axis that modulates the actin cytoskeleton and the migration behavior of CRC cells, and the TRIM65-ARHGAP35 interaction might be a valuable therapeutic target in CRC.

Personalized medicine: From diagnostic to adaptive

Personalized therapy has made great strides but suffers from the lack of companion diagnostics. With the dawn of extracellular vesicle (EV) based liquid biopsies fast approaching, this article proposes a novel approach to cancer treatment – adaptive therapy. Already being implemented in the field of radiation oncology, adaptive radiation therapy utilizes cutting-edge imaging techniques as a viable means to monitor a patient's tumor throughout the entire treatment cycle by adapting the dosage and alignment to match the dynamic tumor. Through an EV liquid biopsy, medical oncologists will also soon have the means to continuously monitor a patient's tumor as it changes over time. With this information, physicians will be able to “adapt” pre-planned therapies concurrently with the fluctuating tumor environment, thus creating a more precise personalized medicine. In this article, a theory for adaptive medicine and the current state of the field with an outlook on future challenges are discussed.

Chemotherapeutic Efficacy of Implantable Antineoplastic-Treatment Protocols in an Optimal Mouse Model for Human Ovarian Carcinoma Cell Targeting

The present study aimed to design and develop a nanocomposite drug delivery system employing an antineoplastic-loaded antibody functionalized nanomicelle encapsulated within a Chitosan⁻Poly(vinylpyrrolidone)⁻Poly(N-isopropylacrylamide) (C⁻P⁻N) hydrogel to form an in situ forming implant (ISFI), responsive to temperature and pH for cancer cell-targeting following intraperitoneal implantation. The optimum nanomicelle formulation was surface-functionalized with anti-MUC 16 (antibody) for the targeted delivery of methotrexate to human ovarian carcinoma (NIH:OVCAR-5) cells in Athymic nude mice that expressed MUC16, as a preferential form of intraperitoneal ovarian cancer (OC) chemotherapy. The cross-linked interpenetrating C⁻P⁻N hydrogel was synthesized for the preparation of an in situ-forming implant (ISFI). Subsequently, the ISFI was fabricated by encapsulating a nanocomposite comprising of anti-MUC16 (antibody) functionalized methotrexate (MTX)-loaded poly(N-isopropylacrylamide)-b-poly(aspartic acid) (PNIPAAm-b-PASP) nanomicelles (AF(MTX)NM's) within the cross-linked C⁻P⁻N hydrogel. This strategy enabled specificity and increased the residence time of the nanomicelles at tumor sites over a period exceeding one month, enhancing uptake of drugs and preventing recurrence and chemo-resistance. Chemotherapeutic efficacy was tested on the optimal ovarian tumor-bearing Athymic nude mouse model and the results demonstrated tumor regression including reduction in mouse weight and tumor size, as well as a significant (p < 0.05) reduction in mucin 16 levels in plasma and ascitic fluid, and improved survival of mice after treatment with the experimental anti-MUC16/CA125 antibody-bound nanotherapeutic implant drug delivery system (ISFI) (p < 0.05). The study also concluded that ISFI could potentially be considered an important immuno-chemotherapeutic agent that could be employed in human clinical trials of advanced, and/or recurring, metastatic epithelial ovarian cancer (EOC). The development of this ISFI may circumvent the treatment flaws experienced with conventional systemic therapies, effectively manage recurrent disease and ultimately prolong disease-free intervals in ovarian cancer patients.

Intranasal administration of resveratrol successfully prevents lung cancer in A/J mice

Lung cancer is the most lethal cancer in the world. About 80% of lung cancer deaths are linked to tobacco use. As a complement to tobacco control, efficient chemoprevention strategies are needed to tackle lung cancer epidemic. Resveratrol is one of the most studied natural products, notably for its cancer chemoprevention properties. However, its low oral bioavailability has often limited the translation of in vitro activities to in vivo effects. While oral administration of resveratrol effectively inhibited colorectal carcinogenesis, it failed to protect mice from chemically-induced lung carcinogenesis. Therefore, non-invasive parenteral routes must be considered to bring resveratrol to the lungs. In the present study, intranasal administration of a concentrated formulation proved to be a valid method to expose the lungs to a sufficient amount of resveratrol. This formulation was administered three times a week for 25 weeks to A/J mice having 4-[methyl(nitroso)amino]-1-(3-pyridinyl)-1-butanone-induced lung carcinogenesis. Resveratrol-treated mice showed a 27% decrease in tumour multiplicity, with smaller tumours, resulting in 45% decrease in tumour volume/mouse. In vitro investigations highlighted apoptosis as a potential mechanism of action. This study presents an effective way to overcome resveratrol low oral bioavailability, encouraging a reevaluation of its use in future clinical trials.

Smoking-associated lung cancer prevention by blockade of the beta-adrenergic receptor-mediated insulin-like growth factor receptor activation

Activation of receptor tyrosine kinases (RTKs) is associated with carcinogenesis, but its contribution to smoking-associated lung carcinogenesis is poorly understood. Here we show that a tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced insulin-like growth factor 1 receptor (IGF-1R) activation via β-adrenergic receptor (β-AR) is crucial for smoking-associated lung carcinogenesis. Treatment with NNK stimulated the IGF-1R signaling pathway in a time- and dose-dependent manner, which was suppressed by pharmacological or genomic blockade of β-AR and the downstream signaling including a Gβγ subunit of β-AR and phospholipase C (PLC). Consistently, β-AR agonists led to increased IGF-1R phosphorylation. The increase in IGF2 transcription via β-AR, signal transducer and activator of transcription 3 (STAT3), and nuclear factor-kappa B (NF-κB) was associated with NNK-induced IGF-1R activation. Finally, treatment with β-AR antagonists suppressed the acquisition of transformed phenotypes in lung epithelial cells and lung tumor formation in mice. These results suggest that blocking β-AR-mediated IGF-1R activation can be an effective strategy for lung cancer prevention in smokers.

Targeted delivery of nano-PTX to the brain tumor-associated macrophages

Nanoparticles containing mixed lipid monolayer shell, biodegradable polymer core and rabies virus glycoprotein (RVG) peptide as brain targeting ligand, were developed for brain targeted delivery of paclitaxel (PTX) to treat malignant glioma. RVG conjugated PTX loaded NPs (RVG-PTX-NPs) had the desirable size (~140 nm), narrow size distribution and spherical shape. RVG-PTX-NPs showed poor uptake by neurons and selective targeting to the brain tumor associated macrophages (TAMs) with controlled release and tumor specific toxicity. In vivo studies revealed that RVG-PTX-NPs were significant to cross the blood-brain barrier (BBB) and had specific targeting to the brain. Most importantly, RVG-PTX-NPs showed effectiveness for anti-glioma therapy on human glioma of mice model. We concluded that RVG-PTX-NPs provided an effective approach for brain-TAMs targeted delivery for the treatment of glioma.

Chemopreventive effects of some popular phytochemicals on human colon cancer: a review

The present review summarizes (1) the epidemiology and etiology of colon cancer, (2) generalized cancer chemoprotective mechanisms, and (3) the chemopreventive properties of some popular phytochemicals as well as some phytochemicals developed by our research group recently.

Cytotoxic, antioxidative, genotoxic and antigenotoxic effects of Horchata, beverage of South Ecuador

BACKGROUND

"Horchata" is an herbal mixture infusion consumed in Southern Ecuador; 66% of its plants are anti-inflammatory medicinal plant, and 51% are analgesics. Anti-inflammatory substances can prevent carcinogenesis mediated by cytotoxic effects and can prevent DNA damage. The aim of this study was to evaluate the cytotoxicity and apoptotic/antigenotoxic effects of horchata as well as its mechanism.

METHODS

Nine different varieties of horchata were prepared in the traditional way and then freeze-dried. Phytochemical screening tested for the presence of secondary metabolites using standard procedures and antioxidant activities. The cytotoxic activity was evaluated on cerebral astrocytoma (D-384), prostate cancer (PC-3), breast cancer (MCF-7), colon cancer (RKO), lung cancer (A-549), immortalized Chinese hamster ovary cells (CHO-K1), and human peripheral blood lymphocytes via a MTS assay. The pro-apoptotic effects were evaluated with Anexin V/Propidium Iodide and western blot of Bax, Bcl-2, TP53, and TP73. Induction and reduction of ROS were assessed by fluorimetry. Genotoxic and antigenotoxic effects were evaluated with a comet assay and micronuclei on binucleated cells.

RESULTS

Five of nine horchatas had cytotoxic effects against D-384 while not affecting normal cells. These horchatas induce cell death by apoptosis modulated by p53/p73. In CHO-K1 cells, the horchatas decrease the damage induced by hydrogen peroxide and Mitomycin C measured in the comet and micronucleus assay respectively.

CONCLUSIONS

The IC50 range of effective horchatas in D-384 was 41 to 122 μg·mL-1. This effect may be related to its use in traditional medicine (brain tonic). On the other hand, immortalized Chinese hamster ovary cells (CHO-K1) and lymphocytes did not show a cytotoxic effect. The most potent horchata induced apoptosis via a p53/p73-mediated mechanism. The horchatas present antigenotoxic properties, which may be related to the antioxidant capacity. Future studies on horchata components are necessary to understand the interactions and beneficial properties.

Medicinal Plants, Effective Plant Compounds (Compositions) and their Effects on Stomach Cancer

Medicinal plants have special importance around the world. Further, they have been noticed for nutrition and illness treatment such as preparation of anticancer new drugs. Therefore, a wide range of studies have been done on different plants, and their anticancer effects have been investigated. Nowadays, cancer is the most important factor of death rate in the developed and developing countries. Among them, stomach cancer is one of the most common malignancies around the world. At present, it is recognized as the fourth common cancer and the second factor of death rate due to cancer. So far, there has been wide range of effort for cancer treatment; however, in most cases, the response to the treatment has been very weak and often accompanied improper subsidiary effects. The present problems as a consequence of chemical treatment and radiotherapy and many subsidiary problems created due to their use for patients, and also, the resistance to the current treatment has motivated researchers to apply new medicines with more effect and less toxicity. The secondary metabolisms existent in the plants have an important role in the treatment of several diseases such as cancer. This study was conducted to investigate and collect scientific results for stomach cancer and to clarify the role of medicinal plants and secondary plant compounds on its treatment.

Cancer in the Medically Underserved Population

Cancer is characterized by uncontrolled growth and spread of abnormal cells. It is the second most common cause of death in the United States, and a significant proportion can be prevented. Underrepresented and underserved populations are less likely to receive routine medical procedures and experience a lower quality of health services. Despite the increase in cancer screening, there are disparities in the incidence and mortality of various cancers. These disparities are not fully explained by the correlations between minority race and lower socioeconomic status or minority race and insurance status. Considerations for global cancer control in low-resource settings are presented.

Nanoparticles as new tools for inhibition of cancer angiogenesis

Angiogenesis is known as one of the hallmarks of cancer. Multiple lines evidence indicated that vascular endothelium growth factor (VEGF) is a key player in the progression of angiogenesis and exerts its functions via interaction with tyrosine kinase receptors (TKRs). These receptors could trigger a variety of cascades that lead to the supply of oxygen and nutrients to tumor cells and survival of these cells. With respect to pivotal role of angiogenesis in the tumor growth and survival, finding new therapeutic approaches via targeting angiogenesis could open a new horizon in cancer therapy. Among various types of therapeutic strategies, nanotechnology has emerged as new approach for the treatment of various cancers. Nanoparticles (NPs) could be used as effective tools for targeting a variety of therapeutic agents. According to in vitro and in vivo studies, NPs are efficient in depriving tumor cells from nutrients and oxygen by inhibiting angiogenesis. However, the utilization of NPs are associated with a variety of limitations. It seems that new approaches such as NPs conjugated with hydrogels could overcome to some limitations. In the present review, we summarize various mechanisms involved in angiogenesis, common anti-angiogenesis strategies, and application of NPs for targeting angiogenesis in various cancers.

Chemoprevention of Colorectal Cancer by Artocarpin, a Dietary Phytochemical from Artocarpus heterophyllus

Artocarpus heterophyllus is an evergreen tree distributed in tropical regions, and its fruit (jackfruit) is well-known as the world's largest tree-borne fruit. Although A. heterophyllus has been widely used in folk medicines against inflammation, its potential in cancer chemoprevention remains unclear. Herein we identified artocarpin from A. heterophyllus as a promising colorectal cancer chemopreventive agent by targeting Akt kinase. Phenotypically, artocarpin exhibited selective cytotoxicity against human colon cancer cells. Artocarpin impaired the anchorage-independent growth capability, suppressed colon cancer cell growth, and induced a G1 phase cell cycle arrest which was followed by apoptotic as well as autophagic cell death. Mechanistic studies revealed that artocarpin directly targeted Akt 1 and 2 kinase activity evidenced by in vitro kinase assay, ex vivo binding assay as well as Akt downstream cellular signal transduction. Importantly, oral administration of artocarpin attenuated colitis-associated colorectal tumorigenesis in mice. Taken together, artocarpin, a bioactive component of A. heterophyllus, might merit investigation as a potential colorectal cancer chemopreventive agent.

Inhibiting breast cancer by targeting the thromboxane A2 pathway

Targeting the estrogen receptor as a strategy has been the gold standard for breast cancer chemoprevention or breast cancer recurrence, but its benefit is limited to estrogen receptor-positive tumors. Cyclooxygenases have been implicated in mammary tumorigenesis. We sought to identify the key prostaglandin responsible for the pro-neoplastic effect of cyclooxygenases and develop prostaglandin-targeted strategies for breast cancer chemoprevention or therapy. Immunohistochemical analysis revealed that either thromboxane A2 synthase 1 or the thromboxane A2 receptor is highly expressed in human breast tumors as well as premalignant lesions, but not in normal mammary tissues. Clinically, the thromboxane A2 pathway might be associated with HER2-positive and axillary lymph node metastasis in human breast cancer. We found that the thromboxane A2 pathway was required for breast cancer cell growth, anchorage-independent growth and invasion capabilities. Importantly, we discovered that switching off thromboxane A2 biosynthesis effectively suppressed either MMTV-HER2-driven mammary tumorigenesis or breast cancer metastasis in preclinical animal models. Taken together, this study established a critical pathophysiological role of the thromboxane A2 pathway in breast cancer, and provided a rationale for introducing a strategy targeting thromboxane A2 for breast cancer chemoprevention and therapy.

Cancer of the Peripheral Nerve in Neurofibromatosis Type 1

The RASopathy neurofibromatosis 1 is an autosomal dominant hereditary cancer syndrome that represents a major risk for the development of malignancies, particularly malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs are unique sarcomas that originate from the peripheral nerve and represent the only primary cancer of the peripheral nervous system. To date, surgery is the only treatment modality proven to have survival benefit for MPNSTs and even when maximal surgery is feasible, these tumors are rarely curable, despite the use of chemotherapy and radiation. In this review, we discuss the current state-of-the-art treatments for MPNSTs, latest therapeutic developments, and critical aspects of the underlying molecular and pathophysiology that appear promising for therapeutic developments in the future. In particular, we discuss the specific elements of cancer in the peripheral nerve and how that may impel development of unique therapies for this form of sarcoma.

Acetonitrile extract of Salvia miltiorrhiza Radix exhibits growth-inhibitory effects on prostate cancer cells through the induction of cell cycle arrest and apoptosis

In the present study, the effects of the acetonitrile or water extracts from 400 selected traditional medicinal plants on the growth of PC-3 cells were investigated, and it was demonstrated that an acetonitrile extract of Salvia miltiorrhiza Radix exhibited the most marked cytotoxic effects on PC-3 cells. It was observed that the acetonitrile extract of S. miltiorrhiza Radix induced marked cell cycle arrest and apoptosis in PC-3 cells through the generation of intracellular reactive oxygen species. It was also demonstrated that oral administration of the acetonitrile extract of S. miltiorrhiza Radix decreased the incidence and growth of PC-3 tumor xenografts in nude mice. The results of the present study suggest that the acetonitrile extract of S. miltiorrhiza Radix exhibits marked inhibitory effects on the growth of prostate cancer cells in vitro and in vivo.

Recent progress in drug delivery of pluronic P123: pharmaceutical perspectives

This review focuses on recent investigations that used Pluronic P123 (P123) as pharmaceutical ingredients in vesicle, micelle, mixed micelle, in situ gel, tablet and emulsion. The main results from these studies show that P123 can significantly increase the stability of incorporated hydrophobic drugs with enhanced in vitro cytotoxicity and cellular uptake of anticancer drugs. Moreover, modified forms of P123 with RGD, folate or other targeted marker have shown its therapeutic potentials in various types of tumors and cancers. Furthermore, modified forms of P123 alone and/or mixed with other copolymers have less toxic effects and more tumor-specific delivery of anticancer drugs. They are promising materials as a nanoplatform for the drug delivery. Finally, the future perspectives of the field are briefly discussed.

Terpenoids as anti-colon cancer agents - A comprehensive review on its mechanistic perspectives

Multistep model of colon carcinogenesis has provided the framework to advance our understanding of the molecular basis of colon cancer. This multistage process of carcinogenesis takes a long period to transform from a normal epithelial cell to invasive carcinoma. Thus, it provides enough time to intervene the process of carcinogenesis especially through dietary modification. In spite of the in-depth understanding of the colon cancer etiology and pathophysiology and its association with diet, colon cancer remains a major cause of cancer mortality worldwide. Phytochemicals and their derivatives are gaining attention in cancer prevention and treatment strategies because of cancer chemotherapy associated adverse effects. Being the largest group of phytochemicals traditionally used for medicinal purpose in India and China, terpenoids are recently being explored as anticancer agents. Anticancer properties of terpenoids are associated with various mechanisms like counteraction of oxidative stress, potentiating endogenous antioxidants, improving detoxification potential, disrupting cell survival pathways and inducing apoptosis. This review gives a comprehensive idea of naturally occurring terpenoids as useful agents for the prevention of colon cancer with reference to their classes, sources and molecular targets. Based on the explored molecular targets further research in colon cancer chemoprevention is warranted.

Anti-Proliferative Effects of Dendrophthoe pentandra Methanol Extract on BCR/ABL-Positive and Imatinib-Resistant Leukemia Cell Lines

Background:

Imatinib mesylate, a tyrosine kinase inhibitor specifically targeting the BCR/ABL fusion protein, induces hematological remission in patients with chronic myeloid leukemia (CML). However, the majority of CML patients treated with imatinib develop resistance with prolonged therapy. Dendrophthoe pentandra (L.) Miq. is a Malaysian mistletoe species that has been used as a traditional treatment for several ailments such as smallpox, ulcers, and cancers.

Methods:

We developed a resistant cell line (designated as K562R) by long-term co-culture of a BCR/ABL positive CML cell line, K562, with imatinib mesylate. We then investigated the anti-proliferative effects of D. pentandra methanol extract on parental K562 and resistant K562R cells. Trypan blue exclusion assays were performed to determine the IC50 concentration; apoptosis and cell cycle analysis were conducted by flow cytometry.

Results:

D. pentandra extract had greater anti-proliferative effects towards K562R (IC50= 192 μg/mL) compared to K562 (500 μg/mL) cells. Upon treatment with D. pentandra extract at the IC50 concentration: K562 but not K562R demonstrated increase in apoptosis and cell cycle arrest in the G2/M phase.

Conclusion:

D. pentandra methanol extract exerts potent anti-proliferative effect on BCR/ABL positive K562 cells.

Absolute Configuration of Dihydro-β-agarofuran Sesquiterpenes from Maytenus jelskii and Their Potential Antitumor-Promoting Effects

Chemoprevention of human cancer appears to be a feasible strategy for cancer control, especially when chemopreventive intervention is involved during early stages of the carcinogenesis process. As a part of our ongoing research program into new chemopreventive agents, herein are reported the isolation, structural elucidation, and biological evaluation of 10 new (1-10) and three known (11-13) sesquiterpenes with a dihydro-β-agarofuran skeleton from the leaves of Maytenus jelskii Zahlbr. Their stereostructures have been elucidated by means of spectroscopic analysis, including 1D and 2D NMR techniques, ECD studies, and biogenetic considerations. The isolated metabolites and eight previously reported sesquiterpenes (14-21) were screened for their antitumor-promoting activity using a short-term in vitro assay for Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). Six compounds from this series (4, 5, 11, and 13-15) were found to exhibit higher efficacies than β-carotene, used as reference inhibitor for EBV-EA activation. In particular, promising antitumor activity was observed for compound 5, exhibiting inhibition even at the lowest concentration assayed (10 mol ratio/TPA). Preliminary structure-activity relationship analysis revealed that the acetate, benzoate, and hydroxy groups are the most desirable substituents on the sesquiterpene scaffold for activity in the EBV-EA activation assay.

Erlotinib and the Risk of Oral Cancer: The Erlotinib Prevention of Oral Cancer (EPOC) Randomized Clinical Trial

IMPORTANCE

Standard molecularly based strategies to predict and/or prevent oral cancer development in patients with oral premalignant lesions (OPLs) are lacking.

OBJECTIVE

To test if the epidermal growth factor receptor inhibitor erlotinib would reduce oral cancer development in patients with high-risk OPLs defined by specific loss of heterozygosity (LOH) profiles. Secondary objectives included prospective determination of LOH as a prognostic marker in OPLs.

DESIGN

The Erlotinib Prevention of Oral Cancer (EPOC) study was a randomized, placebo-controlled, double-bind trial. Accrual occurred from November 2006 through July 2012, with a median follow-up time of 35 months in an ambulatory care setting in 5 US academic referral institutions. Patients with OPLs were enrolled in the protocol, and each underwent LOH profiling (N = 379); they were classified as high-risk (LOH-positive) or low-risk (LOH-negative) patients based on their LOH profiles and oral cancer history. The randomized sample consisted of 150 LOH-positive patients.

INTERVENTIONS

Oral erlotinib treatment (150 mg/d) or placebo for 12 months.

MAIN OUTCOMES AND MEASURES

Oral cancer-free survival (CFS).

RESULTS

A total of 395 participants were classified with LOH profiles, and 254 were classified LOH positive. Of these, 150 (59%) were randomized, 75 each to the placebo and erlotinib groups. The 3-year CFS rates in placebo- and erlotinib-treated patients were 74% and 70%, respectively (hazard ratio [HR], 1.27; 95% CI, 0.68-2.38; P = .45). The 3-year CFS was significantly lower for LOH-positive compared with LOH-negative groups (74% vs 87%, HR, 2.19; 95% CI, 1.25-3.83; P = .01). Increased EGFR gene copy number correlated with LOH-positive status (P < .001) and lower CFS (P = .01). The EGFR gene copy number was not predictive of erlotinib efficacy. Erlotinib-induced skin rash was associated with improved CFS (P = .01).

CONCLUSIONS AND RELEVANCE

In this trial, LOH was validated as a marker of oral cancer risk and found to be associated with increased EGFR copy number (the target of the intervention). Erlotinib did not, however, improve CFS in high-risk patients with LOH-positive or high-EGFR-gene-copy-number OPLs. These results support incorporation of LOH testing as a prognostic tool in routine clinical practice but do not support erlotinib use in this setting.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00402779.

Prognostic factors, predictive markers and cancer biology: the triad for successful oral cancer chemoprevention

Oral squamous cell carcinomas represent a significant cancer burden worldwide. Unfortunately, chemoprevention strategies investigated to date have failed to produce an agent considered standard of care to prevent oral cancers. Nonetheless, recent advances in clinical trial design may streamline drug development in this setting. In this manuscript, we review some of these improvements, including risk prediction tools based on molecular markers that help select patients most suitable for chemoprevention. We also discuss the opportunities that novel preclinical models and modern molecular profiling techniques will bring to the prevention field in the near future, and propose a clinical trials framework that incorporates molecular prognostic factors, predictive markers and cancer biology as a roadmap to improve chemoprevention strategies for oral cancers.

Molecular cancer prevention: Current status and future directions

The heterogeneity and complexity of advanced cancers strongly support the rationale for an enhanced focus on molecular prevention as a priority strategy to reduce the burden of cancer. Molecular prevention encompasses traditional chemopreventive agents as well as vaccinations and therapeutic approaches to cancer-predisposing conditions. Despite challenges to the field, we now have refined insights into cancer etiology and early pathogenesis; successful risk assessment and new risk models; agents with broad preventive efficacy (eg, aspirin) in common chronic diseases, including cancer; and a successful track record of more than 10 agents approved by the US Food and Drug Administration for the treatment of precancerous lesions or cancer risk reduction. The development of molecular preventive agents does not differ significantly from the development of therapies for advanced cancers, yet it has unique challenges and special considerations given that it most often involves healthy or asymptomatic individuals. Agents, biomarkers, cohorts, overall design, and endpoints are key determinants of molecular preventive trials, as with therapeutic trials, although distinctions exist for each within the preventive setting. Progress in the development and evolution of molecular preventive agents has been steadier in some organ systems, such as breast and skin, than in others. In order for molecular prevention to be fully realized as an effective strategy, several challenges to the field must be addressed. Here, the authors provide a brief overview of the context for and special considerations of molecular prevention along with a discussion of the results from major randomized controlled trials.

Hepatic estrogen receptor α improves hepatosteatosis through upregulation of small heterodimer partner

BACKGROUND & AIMS

Estrogen participates in the control of energy homeostasis and lipid metabolism. However the role of hepatic estrogen receptor α (ERα) in triglyceride (TG) homeostasis remains poorly understood. This study aims to investigate the roles of estrogen and ERα in the regulation of hepatic TG metabolism.

METHODS

Liver TG metabolism was analyzed in female mice with ovariectomy or tamoxifen treatment, and in hepatic ERα knockdown or overexpression. Phenotypes and expression of genes were compared in male and female mice with farnesoid X receptor deficiency. The mechanism of ERα in the regulation of small heterodimer partner (SHP) expression was further investigated.

RESULTS

Female mice receiving ovariectomy or tamoxifen treatment exhibited hepatic TG accumulation. Ablation of ERα using adenoviral shRNA markedly increased hepatic TG accumulation, while overexpression of ERα ameliorated hepatosteatosis in obese mice. At the molecular level, estrogen upregulated hepatic SHP expression through binding to its proximal promoter. In addition, the roles of estrogen were largely blunted in mice with SHP deficiency.

CONCLUSION

These findings reveal a novel role of estrogen in improving hepatosteatosis through upregulation of SHP expression.

Dynamics of preventive vs post-diagnostic cancer control using low-impact measures

Cancer poses danger because of its unregulated growth, development of resistance, and metastatic spread to vital organs. We currently lack quantitative theory for how preventive measures and post-diagnostic interventions are predicted to affect risks of a life threatening cancer. Here we evaluate how continuous measures, such as life style changes and traditional treatments, affect both neoplastic growth and the frequency of resistant clones. We then compare and contrast preventive and post-diagnostic interventions assuming that only a single lesion progresses to invasive carcinoma during the life of an individual, and resection either leaves residual cells or metastases are undetected. Whereas prevention generally results in more positive therapeutic outcomes than post-diagnostic interventions, this advantage is substantially lowered should prevention initially fail to arrest tumour growth. We discuss these results and other important mitigating factors that should be taken into consideration in a comparative understanding of preventive and post-diagnostic interventions.

DOI:http://dx.doi.org/10.7554/eLife.06266.001

About one person in every two will get cancer during their lives. Surgery and chemotherapy have long been mainstays of cancer treatment. Both, however, have substantial downsides. Surgery may leave behind undetected cancer cells that can grow into new tumours. Furthermore, in response to chemotherapy drugs, some cancer cells may emerge that resist further treatment. There is therefore interest in whether preventive strategies—including lifestyle changes and medications—could reduce the likelihood of confronting a life-threatening cancer.

Now, Akhmetzhanov and Hochberg have developed a mathematical model to help compare the effectiveness of preventive strategies and traditional cancer treatments. The model—which assumes that a person can only develop a single cancer from a single region of pre-cancerous cells—suggests that long-term cancer prevention strategies reduce the risk of a life-threatening cancer by more than traditional treatment that begins after a tumour is discovered. The preventive measures may be less effective in some cases compared to traditional treatments if they initially fail to stop a tumour growing, although on average they still work better than treating the cancer after detection.

According to Akhmetzhanov and Hochberg's model, surgical removal followed by chemotherapy is less likely to be successful than prevention, and when successful, requires larger impacts on the cancer (and therefore creates more side-effects for the patient) to achieve the same level of control as prevention. The model also suggests that even at very low levels of impact on residual cancer cells, chemotherapies are likely to be counterproductive by boosting the subsequent emergence of treatment-resistant tumours.

Akhmetzhanov and Hochberg's model predicts how effective preventive measures need to be in terms of slowing the growth of cancer cells to result in given reductions in the future risk of a life-threatening cancer. Future work should test this model by measuring the effects on tumour growth of prevention and of traditional therapies.

DOI:http://dx.doi.org/10.7554/eLife.06266.002

Epigenetic drugs for cancer treatment and prevention: mechanisms of action

This review provides a brief overview of the basic principles of epigenetic gene regulation and then focuses on recent development of epigenetic drugs for cancer treatment and prevention with an emphasis on the molecular mechanisms of action. The approved epigenetic drugs are either inhibitors of DNA methyltransferases or histone deacetylases (HDACs). Future epigenetic drugs could include inhibitors for histone methyltransferases and histone demethylases and other epigenetic enzymes. Epigenetic drugs often function in two separate yet interrelated ways. First, as epigenetic drugs per se, they modulate the epigenomes of premalignant and malignant cells to reverse deregulated epigenetic mechanisms, leading to an effective therapeutic strategy (epigenetic therapy). Second, HDACs and other epigenetic enzymes also target non-histone proteins that have regulatory roles in cell proliferation, migration and cell death. Through these processes, these drugs induce cancer cell growth arrest, cell differentiation, inhibition of tumor angiogenesis, or cell death via apoptosis, necrosis, autophagy or mitotic catastrophe (chemotherapy). As they modulate genes which lead to enhanced chemosensitivity, immunogenicity or dampened innate antiviral response of cancer cells, epigenetic drugs often show better efficacy when combined with chemotherapy, immunotherapy or oncolytic virotherapy. In chemoprevention, dietary phytochemicals such as epigallocatechin-3-gallate and sulforaphane act as epigenetic agents and show efficacy by targeting both cancer cells and the tumor microenvironment. Further understanding of how epigenetic mechanisms function in carcinogenesis and cancer progression as well as in normal physiology will enable us to establish a new paradigm for intelligent drug design in the treatment and prevention of cancer.

Diet and esophageal disease

The following, from the 12th OESO World Conference: Cancers of the Esophagus, includes commentaries on macronutrients, dietary patterns, and risk of adenocarcinoma in Barrett's esophagus; micronutrients, trace elements, and risk of Barrett's esophagus and esophageal adenocarcinoma; the role of mate consumption in the development of squamous cell carcinoma; the relationship between energy excess and development of esophageal adenocarcinoma; and the nutritional management of the esophageal cancer patient.

Evasion of anti-growth signaling: A key step in tumorigenesis and potential target for treatment and prophylaxis by natural compounds

The evasion of anti-growth signaling is an important characteristic of cancer cells. In order to continue to proliferate, cancer cells must somehow uncouple themselves from the many signals that exist to slow down cell growth. Here, we define the anti-growth signaling process, and review several important pathways involved in growth signaling: p53, phosphatase and tensin homolog (PTEN), retinoblastoma protein (Rb), Hippo, growth differentiation factor 15 (GDF15), AT-rich interactive domain 1A (ARID1A), Notch, insulin-like growth factor (IGF), and Krüppel-like factor 5 (KLF5) pathways. Aberrations in these processes in cancer cells involve mutations and thus the suppression of genes that prevent growth, as well as mutation and activation of genes involved in driving cell growth. Using these pathways as examples, we prioritize molecular targets that might be leveraged to promote anti-growth signaling in cancer cells. Interestingly, naturally occurring phytochemicals found in human diets (either singly or as mixtures) may promote anti-growth signaling, and do so without the potentially adverse effects associated with synthetic chemicals. We review examples of naturally occurring phytochemicals that may be applied to prevent cancer by antagonizing growth signaling, and propose one phytochemical for each pathway. These are: epigallocatechin-3-gallate (EGCG) for the Rb pathway, luteolin for p53, curcumin for PTEN, porphyrins for Hippo, genistein for GDF15, resveratrol for ARID1A, withaferin A for Notch and diguelin for the IGF1-receptor pathway. The coordination of anti-growth signaling and natural compound studies will provide insight into the future application of these compounds in the clinical setting.

Targeting of chemoprevention to high-risk potentially malignant oral lesions: challenges and opportunities

Worldwide, oral cancer is responsible for 170,000 deaths per year. Intervention to prevent this disease is a long sought after goal. Chemoprevention studies have focused on clinicopathological features of potentially malignant lesions (PML) in an effort to prevent their progression to cancer. However, prediction of future behavior for such lesions is difficult and remains a major challenge to such intervention. Different approaches to this problem have been tested in the past 20years. Early genetic progression models identified critical regions of allelic imbalance at 3p and 9p, and provided the basis for molecular markers to identify progressing PMLs. Subsequently, technological advances, such as genome-wide high-throughput array platforms, computer imaging, visualization technology and next generation sequencing, have broadened the scope for marker development and have the potential of further improving our ability to identify high-risk lesions in the near future either alone or in combination. In this article, we examine the milestones in the development of markers for PML progression. We emphasize the critical importance of networks among scientists, health professionals and community to facilitate the validation and application of putative markers into clinical practice. With a growing number of new agents to validate, it is necessary to coordinate the design and implementation of strategies for patient recruitment, integration of marker assessment, and the final translation of such approaches into clinical use.

BID mediates selective killing of APC-deficient cells in intestinal tumor suppression by nonsteroidal antiinflammatory drugs

Colorectal tumorigenesis is driven by genetic alterations in the adenomatous polyposis coli (APC) tumor suppressor pathway and effectively inhibited by nonsteroidal antiinflammatory drugs (NSAIDs). However, how NSAIDs prevent colorectal tumorigenesis has remained obscure. We found that the extrinsic apoptotic pathway and the BH3 interacting-domain death agonist (BID) are activated in adenomas from NSAID-treated patients. Loss of BID abolishes NSAID-mediated tumor suppression, survival benefit, and apoptosis in tumor-initiating stem cells in APC(Min/+) mice. BID-mediated cross-talk between the extrinsic and intrinsic apoptotic pathways is responsible for selective killing of neoplastic cells by NSAIDs. We further demonstrate that NSAIDs induce death receptor signaling in both cancer and normal cells, but only activate BID in cells with APC deficiency and ensuing c-Myc activation. Our results suggest that NSAIDs suppress intestinal tumorigenesis through BID-mediated synthetic lethality triggered by death receptor signaling and gatekeeper mutations, and provide a rationale for developing more effective cancer prevention strategies and agents.