Quercetin inhibits prostate cancer by attenuating cell survival and inhibiting anti-apoptotic pathways

Background

Despite recent advances in diagnosis and treatment, prostate cancer (PCa) remains the leading cause of cancer-related deaths in men. Current treatments offered in the clinics are often toxic and have severe side effects. Hence, to treat and manage PCa, new agents with fewer side effects or having potential to reduce side effects of conventional therapy are needed. In this study, we show anti-cancer effects of quercetin, an abundant bioflavonoid commonly used to treat prostatitis, and defined quercetin-induced cellular and molecular changes leading to PCa cell death.

Methods

Cell viability was assessed using MTT. Cell death mode, mitochondrial outer membrane potential, and oxidative stress levels were determined by flow cytometry using Annexin V-7 AAD dual staining kit, JC-1 dye, and ROS detection kit, respectively. Antibody microarray and western blot were used to delineate the molecular changes induced by quercetin.

Results

PCa cells treated with various concentrations of quercetin showed time- and dose-dependent decrease in cell viability compared to controls, without affecting normal prostate epithelial cells. Quercetin led to apoptotic and necrotic cell death in PCa cells by affecting the mitochondrial integrity and disturbing the ROS homeostasis depending upon the genetic makeup and oxidative status of the cells. LNCaP and PC-3 cells that have an oxidative cellular environment showed ROS quenching after quercetin treatment while DU-145 showed rise in ROS levels despite having a highly reductive environment. Opposing effects of quercetin were also observed on the pro-survival pathways of PCa cells. PCa cells with mutated p53 (DU-145) and increased ROS showed significant reduction in the activation of pro-survival Akt pathway while Raf/MEK were activated in response to quercetin. PC-3 cells lacking p53 and PTEN with reduced ROS levels showed significant activation of Akt and NF-κB pathway. Although some of these changes are commonly associated with oncogenic response, the cumulative effect of these alterations is PCa cell death.

Conclusions

Our results demonstrated quercetin exerts its anti-cancer effects by modulating ROS, Akt, and NF-κB pathways. Quercetin could be used as a chemopreventive option as well as in combination with chemotherapeutic drugs to improve clinical outcomes of PCa patients.

Aspirin restores ABT-737-mediated apoptosis in human renal carcinoma cells

Aspirin is a novel chemopreventive agent against malignancy. However, outcomes of aspirin monotherapy of renal cell carcinoma (RCC) are inconsistent across studies. ABT-737, an BH3 mimetic inhibitor, is also a promising antitumor drug. Cancer cells including those from RCC, that have high levels of Mcl-1, are refractory to ABT-737-induced apoptosis. We here investigated how aspirin treatment modulates the ABT-737-induced apoptosis. Using the in vitro model of human 786-O cells, we showed that aspirin had sensitized cells to ABT-737 induced apoptosis. Such aspirin-induced changes of ABT-737 resistance was accompanied by a host of biochemical events like protein phosphatase 2A (PP2A) activation, AKT dephosphorylation, Mcl-1/FLICE inhibiting protein (FLIP)/XIAP downregulation, and Bax mitochondrial redistribution. The PP2A inhibitor, okadaic acid, was able to reverse the apirin-induced apoptotic changes. Apart from the aspirin treatment, Mcl-1 silencing also rendered cells vulnerable to ABT-737 induced apoptosis. Since PP2A, Akt, and Mcl-1 play critical roles in RCC malignancy and treatment resistance, our present study showed that aspirin, an alternative adjuvant agent, had recalled ABT-737 sensitivity in the RCC cells through processes involving the PP2A/Akt/Mcl-1 axis.

Phenolics from Barleria cristata var. Alba as carcinogenesis blockers against menadione cytotoxicity through induction and protection of quinone reductase

Background

There are increasing interests in natural compounds for cancer chemoprevention. Blocking agents represent an important class of chemopreventive compounds. They prevent carcinogens from undergoing metabolic activation and thereby suppressing their interaction with cellular macromolecular targets.

Methods

The effect of phenolic compounds isolated from Barleria cristata var. alba as chemopreventive agent was evaluated. The ethyl acetate fraction of B. cristata was subjected to different chromatographic techniques for isolation of its major phenolic compounds. The isolated compounds were evaluated for their potential to induce the cancer chemopreventive enzyme marker NAD(P)H quinonereductase 1 (NQO1) in murine Hepa-1c1c7 cell model.

Results

The ethyl acetate fraction of B. cristata var. alba yielded five known compounds identified as verbascoside (1), isoverbascoside (2), dimethoxyverbascoside (3), p-hydroxy benzoic acid (4), and apigenin-7-O-glucoside (5). Among the tested compounds, isoverbascoside (2) was shown to potently induce the activity of the enzyme in a dose –dependent manner. As a functional assay for detoxification, compound 2 was the strongest to protect Hepa-1c1c7 against the toxicity of menadione, a quinone substrate for NQO1.

Conclusion

This effect seemed to be attributed to the compound’s potential to induce both the catalytic activity and protein expression of NQO1 as revealed by enzyme assay and Western blotting, respectively.

Electronic supplementary material

The online version of this article (10.1186/s12906-018-2214-9) contains supplementary material, which is available to authorized users.

Risk of gastric cancer development after eradication of Helicobacter pylori

Helicobacter pylori (H. pylori) infection is the most important risk factor for gastric cancer (GC) development through the Correa’s gastric carcinogenesis cascade. However, H. pylori eradication alone does not eliminate GC, as pre-neoplastic lesions (atrophic gastritis, intestinal metaplasia and dysplasia) may have already developed in some patients. It is therefore necessary to identify patients at high-risk for gastric cancer after H. pylori eradication to streamline the management plan. If the patients have not undergone endoscopy with histologic assessment, the identification of certain clinical risk factors and non-invasive testing (serum pepsinogen) can predict the risk of atrophic gastritis. For those with suspected atrophic gastritis, further risk stratification by endoscopy with histologic assessment according to validated histologic staging systems would be advisable. Patients with higher stages may require long-term endoscopic surveillance. Apart from secondary prevention to reduce deaths by diagnosing GC at an early stage, identifying medications that could potentially modify the GC risk would be desirable. The potential roles of a number of medications have been suggested by various studies, including proton pump inhibitors (PPIs), aspirin, statins and metformin. However, there are currently no randomized clinical trials to address the impact of these medications on GC risk after H. pylori eradication. In addition, most of these studies failed to adjust for the effect of concurrent medications on GC risk. Recently, large population-based retrospective cohort studies have shown that PPIs were associated with an increased GC risk after H. pylori eradication, while aspirin was associated with a lower risk. The roles of other agents in reducing GC risk after H. pylori eradication remain to be determined.

Microbiota modification by probiotic supplementation reduces colitis associated colon cancer in mice

AIM

To investigate the effect of probiotic supplementation during the development of an experimental model of colitis associated colon cancer (CAC).

METHODS

C57BL/6 mice received an intraperitoneal injection of azoxymethane (10 mg/kg), followed by three cycles of sodium dextran sulphate diluted in water (5% w/v). Probiotic group received daily a mixture of Lactobacillus acidophilus, Lactobacillus rhamnosus and Bifidobacterium bifidum. Microbiota composition was assessed by 16S rRNA Illumina HiSeq sequencing. Colon samples were collected for histological analysis. Tumor cytokines was assessed by Real Time-PCR (Polymerase Chain Reaction); and serum cytokines by Multiplex assay. All tests were two-sided. The level of significance was set at P < 0.05. Graphs were generated and statistical analysis performed using the software GraphPad Prism 5.0. The project was approved by the institutional review board committee.

RESULTS

At day 60 after azoxymethane injection, the mean number of tumours in the probiotic group was 40% lower than that in the control group, and the probiotic group exhibited tumours of smaller size (< 2 mm) (P < 0.05). There was no difference in richness and diversity between groups. However, there was a significant difference in beta diversity in the multidimensional scaling analysis. The abundance of the genera Lactobacillus, Bifidobacterium, Allobaculum, Clostridium XI and Clostridium XVIII increased in the probiotic group (P < 0.05). The microbial change was accompanied by reduced colitis, demonstrated by a 46% reduction in the colon inflammatory index; reduced expression of the serum chemokines RANTES and Eotaxin; decreased p-IKK and TNF-α and increased IL-10 expression in the colon.

CONCLUSION

Our results suggest a potential chemopreventive effect of probiotic on CAC. Probiotic supplementation changes microbiota structure and regulates the inflammatory response, reducing colitis and preventing CAC.

A small diversity library of α-methyl amide analogs of sulindac for probing anticancer structure-activity relationships

Non-steroidal anti-inflammatory drugs (NSAIDs) have a variety of potential indications that include management of pain and inflammation as well as chemoprevention and/or treatment of cancer. Furthermore, a specific form of ibuprofen, dexibuprofen or the S-(+) form, shows interesting neurological activities and has been proposed for the treatment of Alzheimer's disease. In a continuation of our work probing the anticancer activity of small sulindac libraries, we have prepared and screened a small diversity library of α-methyl substituted sulindac amides in the profen class. Several compounds of this series displayed promising activity compared with a lead sulindac analog.

The protective effect of some Thai plants and their bioactive compounds in UV light-induced skin carcinogenesis

Skin cancer, represents a major public health concern. While the vast majority is non-melanoma skin cancers, melanomas are mostly responsible for mortality. Solar UVB radiation is mutagenic and carcinogenic. It is primarily responsible for both non-melanoma and melanoma skin cancers via excessive production of reactive oxygen species (ROS), which mediate changes in inflammation and immunity, and have been implicated in all three stages of skin cancer development. Due to their regulatory role in numerous functions of cells, signaling pathways are targets for chemoprevention. The current standards in melanoma therapy are targeted and combination therapies, which, albeit prolong survival responses, are still prone to development of drug resistance. To this extent, drugs of natural origin continue to spark great interest. Thailand has a rich biodiversity of indigenous flora, which have traditionally been used to treat a variety of pathologies. The active components in plant extracts that have medicinal properties, termed 'bioactive compounds,' are efficient chemopreventive agents due to their antioxidant, antimutagenic, anticarcinogenic, and carcinogen detoxification properties. Thai plants and their bioactive compounds have shown protective effects on UV light-induced skin cancer in different experimental models. This warrants further in vivo investigations and translation to clinical studies to determine efficacy and safety, for use as lead compounds in targeted/combination therapy or adjuvant therapy with existing regimes. Coupled with a strategy for prevention, this offers a promising outlook for protection against photocarcinogenesis.

The Chemoprevention of Ovarian Cancer: the Need and the Options

PURPOSE OF REVIEW

Ovarian cancer (OvCa) is the most lethal of all gynecological cancers, with a 5-year survival around 46%, mainly due to limitations in early diagnosis and treatment. Consequently, the chemoprevention of OvCa emerges as an important option to control this dismal disease. Here, we discuss the role of risk assessment in the design of chemoprevention strategies for OvCa, describe candidate agents, and assess future directions in this field.

RECENT FINDINGS

OvCa chemoprevention represents an opportunity for all women, especially those at high risk such as carriers of BRCA1 or BRCA2 mutations. The use of oral contraceptives confers substantial protection against OvCa including women at high risk, which increases with longer use. Despite strong evidence for their efficacy, safety concerns and the magnitude of the requisite interventional clinical trials seem to have precluded definitive studies of oral contraceptives for this application. Several other classes of drugs, including non-steroidal anti-inflammatory drugs, retinoids, angiopreventive agents, poly(ADP-ribose) polymerase inhibitors, and tyrosine kinase inhibitors have shown promise for OvCa chemoprevention.

SUMMARY

Currently, no agent is proven by interventional trials to possess chemopreventive properties against OvCa. The key opportunities in the chemoprevention of OvCa include the development of surrogate biomarkers for OvCa, the molecular definition of OvCa risk that will help select those who may benefit the most from chemoprevention, the identification of additional agents likely driven by understanding the molecular pathogenesis of OvCa, and the development of dedicated resources and support mechanisms for OvCa. Overall, there is significant optimism for the future of OvCa chemoprevention.

To compare the effectiveness of different mouthrinses on Streptococcus mutans count in caries active children

INTRODUCTION

Streptococcus mutans is the prime microbe responsible for caries. Mouthwashes represent an effective means for decreasing their count. To ascertain this, three commercially available mouthrinses were evaluated for their antimicrobial activity.

MATERIALS AND METHOD

Chlorhexidine, Sodium fluoride and Herbal mouth rinse were evaluated for their efficacy against S. mutans in 60 children aged 6-12 years old. Plain water acted as the control group.

RESULTS

The values obtained were subjected to statistical analysis. ANOVA test, student-t test and paired t-test were used for evaluation. Chlorhexidine and fluoride showed statistically significant reduction in S. mutans count as compared to herbal rinse.

CONCLUSION

All the mouthrinses used in the present study have shown a definite decline in S. mutans count.

Suppression of glutathione S-transferases potentiates the cytotoxic effect of phenethyl isothiocyanate in cholangiocarcinoma cells

Phenethyl isothiocyanate (PEITC) is a potential cancer prevention agent that is found in cruciferous vegetables. Previous studies have shown that the effect of PEITC-induced cell death declines rapidly after administration. The metabolic fate of PEITC is modulated by glutathione S-transferases (GST). In this study, we investigated whether GST activity modulates PEITC-induced cytotoxicity on cholangiocarcinoma (CCA) cells. The sensitivity of KKU-M214 and KKU-100 cells to PEITC was associated with GST activity. Two GST inhibitors, ethacrynic acid (EA) and cibacron blue, potentiated the cytotoxic effect of PEITC in CCA cells. PEITC-induced glutathione (GSH) depletion and redox stress, whereas EA itself or in combination with PEITC did not alter GSH redox status. The enhanced cytotoxic effect of EA may be due to inhibition of GST activity. This idea was validated by using siRNA directed against GSTP1 mRNA in KKU-M214 cells, and GSTP1 and GSTT1 mRNA in KKU-100 cells. These GST isoforms were abundantly expressed in the cell lines. Knockdown of GSTs in CCA cell lines potentiated the cytotoxic effect of PEITC. The present study shows that the antitumor effect of PEITC was potentiated by the suppression of GST activity. The inhibition of GST could be a crucial strategy to potentiate chemotherapeutic effect of PEITC on CCA.

Acetyl-l-carnitine is an anti-angiogenic agent targeting the VEGFR2 and CXCR4 pathways

Carnitines play an important role in the energy exchange in cells, and are involved in the transport of fatty acids across the inner mitochondrial membrane. l-Acetylcarnitine (ALCAR) is an acetic acid ester of carnitine that has higher bioavailability and is considered a fat-burning energizer supplement. We previously found that in serum samples from prostate cancer (PCa) patients, 3 carnitine family members were significantly decreased, suggesting a potential protective role of carnitine against PCa. Several studies support beneficial effects of carnitines on cancer, no study has investigated the activities of carnitine on tumor angiogenesis. We examined whether ALCAR acts as an "angiopreventive" compound and studied the molecular mechanisms involved. We found that ALCAR was able to limit inflammatory angiogenesis by reducing stimulated endothelial cell and macrophage infiltration in vitro and in vivo. Molecularly, we show that ALCAR downregulates VEGF, VEGFR2, CXCL12, CXCR4 and FAK pathways. ALCAR blocked the activation of NF-κB and ICAM-1 and reduced the adhesion of a monocyte cell line to endothelial cells. This is the first study showing that ALCAR has anti-angiogenic and anti-inflammatory properties and might be an attractive candidate for cancer angioprevention.

Comparative effectiveness of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers in chemoprevention of hepatocellular carcinoma: a nationwide high-risk cohort study

Background

Research has revealed that angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) may prevent cancers such as hepatocellular carcinoma (HCC). The comparative chemopreventive effects of ACEIs and ARBs in high-risk populations with hepatitis B virus (HBV) or hepatitis C virus (HCV) infection have yet to be investigated.

Methods

From 2005 to 2014, high-risk HBV and HCV cohorts of hypertensive patients without HCC history were recruited from three linked national databases of Taiwan, and were classified into two groups based on the ACEI or ARB exposure within the initial six months after initiating antiviral agent. Intergroup differences in clinical characteristics and duration of drug exposure within study period were evaluated. HCC-free survival was compared using the log-rank test. Multivariate Cox regression including time-dependent variables for the use of ACEIs or ARBs and other medications was applied to adjust for confounders.

Results

Among the 7724 patients with HBV and 7873 with HCV, 46.3% and 42.5%, respectively, had an initial exposure to ACEIs or ARBs. The median durations of exposure were 36.4 and 38.9 months for the HBV and HCV cohorts, respectively. The median durations of ACEI or ARB use during study period between initial exposure and nonexposure groups were 41.8 vs. 18.3 months and 46.4 vs. 22.7 months for the HBV and HCV cohorts, respectively. No significant difference was observed in HCC risk within 7 years between the initial exposure and non-exposure groups. After adjustment for comorbidities, namely liver cirrhosis, diabetes mellitus (DM), and hyperlipidemia, and medications, namely aspirin, metformin, and statins, the hazard ratios (HRs) for ACEI or ARB exposure for HCC risk were 0.97 (95% confidence interval [CI]: 0.81–1.16) and 0.96 (0.80–1.16) in the HBV and HCV cohorts, respectively. In the HCV cohort, the increased HCC risk was associated with ACEI or ARB use in patients without cirrhosis, DM, and hyperlipidemia (HR: 4.53, 95% CI: 1.46–14.1).

Conclusion

Compared with other significant risk and protective factors for HCC, ACEI or ARB use in the HBV and HCV cohorts was not associated with adequate protective effectiveness under standard dosages and may not be completely safe.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4292-y) contains supplementary material, which is available to authorized users.

Beyond COX-1: the effects of aspirin on platelet biology and potential mechanisms of chemoprevention

After more than a century, aspirin remains one of the most commonly used drugs in western medicine. Although mainly used for its anti-thrombotic, anti-pyretic, and analgesic properties, a multitude of clinical studies have provided convincing evidence that regular, low-dose aspirin use dramatically lowers the risk of cancer. These observations coincide with recent studies showing a functional relationship between platelets and tumors, suggesting that aspirin's chemopreventive properties may result, in part, from direct modulation of platelet biology and biochemistry. Here, we present a review of the biochemistry and pharmacology of aspirin with particular emphasis on its cyclooxygenase-dependent and cyclooxygenase-independent effects in platelets. We also correlate the results of proteomic-based studies of aspirin acetylation in eukaryotic cells with recent developments in platelet proteomics to identify non-cyclooxygenase targets of aspirin-mediated acetylation in platelets that may play a role in its chemopreventive mechanism.

Regular Use of Aspirin or Non-Aspirin Nonsteroidal Anti-Inflammatory Drugs Is Not Associated With Risk of Incident Pancreatic Cancer in Two Large Cohort Studies

BACKGROUND & AIMS

Use of aspirin and/or non-aspirin nonsteroidal anti-inflammatory drugs (NSAIDs) reduces the risk of several cancers, but it is not clear if use of these drugs is associated with risk of pancreatic cancer.

METHODS

We evaluated aspirin and non-aspirin NSAID use and risk of pancreatic adenocarcinoma in 141,940 participants from the Health Professionals Follow-up Study and Nurses' Health Study using multivariable-adjusted Cox proportional hazards regression. We considered several exposure classifications to model differing lag times between NSAID exposure and cancer development. We also conducted a nested case-control study of participants from 3 prospective cohorts using conditional logistic regression to evaluate pre-diagnosis levels of plasma salicylurate, a major metabolite of aspirin, in 396 pancreatic cancer cases and 784 matched individuals without pancreatic cancer (controls).

RESULTS

In the prospective cohort study, 1122 participants developed pancreatic adenocarcinoma over 4.2 million person-years. Use of aspirin or non-aspirin NSAIDs was not associated with pancreatic cancer risk, even after considering several latency exposure classifications. In a pre-planned subgroup analysis, regular aspirin use was associated with reduced pancreatic cancer risk among participants with diabetes (relative risk, 0.71; 95% CI, 0.54-0.94). In the nested case-control study, pre-diagnosis levels of salicylurate were not associated with pancreatic cancer risk (odds ratio, 1.08; 95% CI, 0.72-1.61; Ptrend 0.81; comparing participants in the highest quintile with those in the lowest quintile of plasma salicylurate).

CONCLUSIONS

Regular aspirin or non-aspirin NSAID use was not associated with future risk of pancreatic cancer in participants from several large prospective cohort studies. A possible reduction in risk for pancreatic cancer among people with diabetes who regularly use aspirin should be further examined in preclinical and human studies.

Lycopene Protects Against Spontaneous Ovarian Cancer Formation in Laying Hens

Background

Dietary intake of lycopene has been associated with a reduced risk of ovarian cancer, suggesting its chemopreventive potential against ovarian carcinogenesis. Lycopene's molecular mechanisms of action in ovarian cancer have not been fully understood. Therefore, in the present study, we investigated the effects of lycopene on the ovarian cancer formation using the laying hen model, a biologically relevant animal model of spontaneous ovarian carcinogenesis due to high incidence rates similar to humans.

Methods

In this study, a total of 150 laying hens at age of 102 weeks were randomized into groups of 50: a control group (0 mg of lycopene per kg of diet) and two treatment groups (200 mg or 400 mg of lycopene per kg of diet, or ~26 and 52 mg/d/hen, respectively). At the end of 12 months, blood, ovarian tissues and tumors were collected.

Results

We observed that lycopene supplementation significantly reduced the overall ovarian tumor incidence (P < 0.01) as well as the number and the size of the tumors (P < 0.004 and P < 0.005, respectively). Lycopene also significantly decreased the rate of adenocarcinoma, including serous and mucinous subtypes (P < 0.006). Moreover, we also found that the serum level of oxidative stress marker malondialdehyde was significantly lower in lycopene-fed hens compared to control birds (P < 0.001). Molecular analysis of the ovarian tumors revealed that lycopene reduced the expression of NF-κB while increasing the expression of nuclear factor erythroid 2 and its major target protein, heme oxygenase 1. In addition, lycopene supplementation decreased the expression of STAT3 by inducing the protein inhibitor of activated STAT3 expression in the ovarian tissues.

Conclusions

Taken together, our findings strongly support the potential of lycopene in the chemoprevention of ovarian cancer through antioxidant and anti-inflammatory mechanisms.

Personalized prevention in high risk individuals: Managing hormones and beyond

Increasing numbers of women are being identified at 'high-risk' of breast cancer, defined by The National Institute of Health and Care Excellence (NICE) as a 10-year risk of ≥8%. Classically women have been so identified through family history based risk algorithms or genetic testing of high-risk genes. Recent research has shown that assessment of mammographic density and single nucleotide polymorphisms (SNPs), when combined with established risk factors, trebles the number of women reaching the high risk threshold. The options for risk reduction in such women include endocrine chemoprevention with the selective estrogen receptor modulators tamoxifen and raloxifene or the aromatase inhibitors anastrozole or exemestane. NICE recommends offering anastrozole to postmenopausal women at high-risk of breast cancer as cost effectiveness analysis showed this to be cost saving to the National Health Service. Overall uptake to chemoprevention has been disappointingly low but this may improve with the improved efficacy of aromatase inhibitors, particularly the lack of toxicity to the endometrium and thrombogenic risks. Novel approaches to chemoprevention under investigation include lower dose and topical tamoxifen, denosumab, anti-progestins and metformin. Although oophorectomy is usually only recommended to women at increased risk of ovarian cancer it has been shown in numerous studies to reduce breast cancer risks in the general population and in those with mutations in BRCA1/2. However, recent evidence from studies that have confined analysis to true prospective follow up have cast doubt on the efficacy of oophorectomy to reduce breast cancer risk in BRCA1 mutation carriers, at least in the short-term.

Risk factors and prevention of hepatocellular carcinoma in the era of precision medicine

Patients who develop chronic fibrotic liver disease, caused by viral or metabolic aetiologies, are at a high risk of developing hepatocellular carcinoma (HCC). Even after complete HCC tumour resection or ablation, the carcinogenic tissue microenvironment in the remnant liver can give rise to recurrent de novo HCC tumours, which progress into incurable, advanced-stage disease in most patients. Thus, early detection and prevention of HCC development is, in principle, the most impactful strategy to improve patient prognosis. However, a "one-size-fits-all" approach to HCC screening for early tumour detection, as recommended by clinical practice guidelines, is utilised in less than 20% of the target population, and the performance of screening modalities, including ultrasound and alpha-fetoprotein, is suboptimal. Furthermore, optimal screening strategies for emerging at-risk patient populations, such as those with chronic hepatitis C after viral cure, or those with non-cirrhotic, non-alcoholic fatty liver disease remain controversial. New HCC biomarkers and imaging modalities may improve the sensitivity and specificity of HCC detection. Clinical and molecular HCC risk scores will enable precise HCC risk prediction followed by tailoured HCC screening of individual patients, maximising cost-effectiveness and optimising allocation of limited medical resources. Several aetiology-specific and generic HCC chemoprevention strategies are evolving. Epidemiological and experimental studies have identified candidate chemoprevention targets and therapies, including statins, anti-diabetic drugs, and selective molecular targeted agents, although their clinical testing has been limited by the lengthy process of cancer development that requires long-term, costly studies. Individual HCC risk prediction is expected to overcome the challenge by enabling personalised chemoprevention, targeting high-risk patients for precision HCC prevention and substantially improving the dismal prognosis of HCC.

Chemoprevention of Skin Carcinomas in High-Risk Transplant Recipients

BACKGROUND

Long-term immunosuppressive therapy, as provided to solid organ transplant recipients, inevitably results in a significant inhibition of immune defenses; this leads to frequent skin infections and malignancies, which represent an important cause of morbidity and mortality for transplanted patients. The incidence and risk of skin carcinomas are elevated in solid organ transplant recipients in comparison with the general population, with a 10-fold increased risk for basal cell carcinoma and a 50-100-fold for squamous cell carcinoma. The schedule of immunosuppressive drugs influences the type and timing of skin malignancies, but a crucial role is also played by endogenous and exogenous risk factors.

METHODS & RESULTS

Here, we will review the state-of-the-art in chemoprevention of epidermal carcinomas in order to provide useful information for clinicians involved in the management of transplant recipients. One-hundred and forteen paper, published on peerreviewed journals, has been included.

CONCLUSION

Chemoprevention would be key in controlling skin carcinogenesis in high-risk patients.

Prostate cancer chemoprevention by natural agents: Clinical evidence and potential implications

Prostate cancer (PCa) is the most common non-skin cancer and the second leading cause of cancer-related deaths in American men. Due to its long latency period, PCa is considered as an ideal cancer type for chemopreventive interventions. Chemopreventive agents include various natural or synthetic agents that prevent or delay cancer development, progression and/or recurrence. Pre-clinical studies suggest that many natural products and dietary agents have chemopreventive properties. However, a limited number of these agents have been tested in clinical trials, with varying success. In this review, we have discussed the available clinical studies regarding the efficacy of natural chemopreventive agents against PCa, including tea polyphenols, selenium, soy proteins, vitamins and resveratrol. We have also provided a discussion on the clinical challenges and opportunities for the potential use of chemopreventive agents against PCa. Based on available literature, it appears that the variable outcomes of the chemopreventive clinical studies necessitate a need for additional studies with more rigorous designs and methodical interpretations in order to measure the potential of the natural agents against PCa.

Modulation of CYP1A1 metabolism: From adverse health effects to chemoprevention and therapeutic options

The human cytochrome P450 (CYP) 1A1 gene encodes a monooxygenase that metabolizes multiple exogenous and endogenous substrates. CYP1A1 has become infamous for its oxidative metabolism of benzo[a]pyrene and related polycyclic aromatic hydrocarbons, converting these chemicals into very potent human carcinogens. CYP1A1 expression is mainly controlled by the aryl hydrocarbon receptor (AHR), a transcription factor whose activation is induced by binding of persistent organic pollutants, including polycyclic aromatic hydrocarbons and dioxins. Accordingly, induction of CYP1A1 expression and activity serves as a biomarker of AHR activation and associated xenobiotic metabolism as well as toxicity in diverse animal species and humans. Determination of CYP1A1 activity is integrated into modern toxicological concepts and testing guidelines, emphasizing the tremendous importance of this enzyme for risk assessment and regulation of chemicals. Further, CYP1A1 serves as a molecular target for chemoprevention of chemical carcinogenesis, although present literature is controversial on whether its inhibition or induction exerts beneficial effects. Regarding therapeutic applications, first anti-cancer prodrugs are available, which require a metabolic activation by CYP1A1, and thus enable a specific elimination of CYP1A1-positive tumors. However, the application range of these drugs may be limited due to the frequently observed downregulation of CYP1A1 in various human cancers, probably leading to a reduced metabolism of endogenous AHR ligands and a sustained activation of AHR and associated tumor-promoting responses. We here summarize the current knowledge on CYP1A1 as a key player in the metabolism of exogenous and endogenous substrates and as a promising target molecule for prevention and treatment of human malignancies.

Synergy of 2-deoxy-D-glucose combined with berberine in inducing the lysosome/autophagy and transglutaminase activation-facilitated apoptosis

Utilizing a variety of flow cytometric methods evidence was obtained indicating that a combination of the glucose analog 2-deoxy-D-glucose (2-dG) and the plant alkaloid berberine (BRB) produces synergistic effect in the induction of apoptosis in human lymphoblastoid TK6 cells. The synergistic effect is seen at concentrations of the drugs at which each of them alone shows no cytotoxicity at all. The data suggest that the combination of these drugs, which are known in terms of their overall toxicity, side effects and pharmacokinetics may be considered for further studies as chemopreventive and cancer treatment modalities. Of interest are results indicating that rapamycin, which similarly to BRB, suppresses mTOR signaling, when combined with 2-dG shows no synergistic properties. Metformin, on other hand, requires much higher concentration to show the synergy with 2-dG. Also of interest are the findings pertaining to the methodology of the present study. Specifically, dynamic assessment of cellular viability was performed by using the DRAQ7 cell exclusion fluorochrome present in cultures from 0 to 72 h. Concurrent measurement of lysosomal proton pump using acridine orange as the probe shows activation of lysosomes in the cells treated with 2-dG or BRB alone as well as with the drugs combined. Apoptosis was assessed by measuring DNA fragmentation, cell cycle, activation of caspase-3 and tissue transglutaminase (Tgase). A novel cytometric method was developed based on analysis of lysosomal (acidic vesicles) proton pump in live cells followed by cell lysis with detergent and fluorochrome labeling of proteins and DNA to analyze Tgase activation concurrently with cell cycle, in same population of cells. The data show that the cell subpopulation undergoing apoptosis has increased side (right-angle) light scatter likely due to the presence of the crosslinked (solid state) proteins, the consequence Tgase activation.

Glucosamine use and risk of colorectal cancer: results from the Cancer Prevention Study II Nutrition Cohort

PURPOSE

Use of glucosamine supplements has been associated with reduced risk of colorectal cancer (CRC) in previous studies; however, information on this association remains limited.

METHODS

We examined the association between glucosamine use and CRC risk among 113,067 men and women in the Cancer Prevention Study II Nutrition Cohort. Glucosamine use was first reported in 2001 and updated every 2 years thereafter. Participants were followed from 2001 through June of 2011, during which time 1440 cases of CRC occurred.

RESULTS

As has been observed in prior studies, current use of glucosamine, modeled using a time-varying exposure, was associated with lower risk of CRC (HR 0.83; 95% CI 0.71-0.97) compared to never use. However, for reasons that are unclear, this reduction in risk was observed for shorter-duration use (HR 0.68; 95% CI 0.52-0.87 for current users with ≤ 2 years use) rather than longer-duration use (HR 0.90; 95% CI 0.72-1.13 for current users with 3 to < 6 years of use; HR 0.99; 95% CI 0.76-1.29 for current users with ≥ 6 years of use).

CONCLUSIONS

Further research is needed to better understand the association between glucosamine use and risk of CRC, and how this association may vary by duration of use.

[6]-Shogaol attenuates inflammation, cell proliferation via modulate NF-κB and AP-1 oncogenic signaling in 7,12-dimethylbenz[a]anthracene induced oral carcinogenesis

Nuclear factor-kappaB (NF-κB) and activator protein 1 (AP-1) is a major transcription factor which regulates many biological and pathological processes such as inflammation and cell proliferation, which are major implicates in cancer progression. [6]-Shogaol ([6]-SHO) is a major constituent of ginger, exhibits various biological properties such as anti-oxidants, anti-inflammation and anti-tumor. Recently, we proven that [6]-SHO prevents oral squamous cell carcinoma by activating proapoptotic factors in in vitro and in vivo experimental model. However, the preventive efficacy of [6]-SHO in 7,12-dimethylbenz[a]anthracene (DMBA) induced hamster buccal pouch carcinogenesis (HBP) has not been fully elucidated, so far. Hence, we aimed to investigate the effect of [6]-SHO on inflammation and cell proliferation by inhibiting the translocation of NF-κB and AP-1 in DMBA induced HBP carcinogenesis. In this study, we observed upregulation of inflammatory markers (COX-2, iNOS, TNF-α, interleukin-1 and -6), cell proliferative markers (Cyclin D1, PCNA and Ki-67) and aberrant activation of NF-κB, AP-1, IKKβ, c-jun, c-fos and decreased IκB-α in DMBA induced hamsters. Conversely, oral administration of [6]-SHO strongly inhibited constitutive phosphorylation and degradation of IκB and inhibit phosphorylation of c-jun, c-fos, resulting in inhibition of nuclear translocation of NF-κBp65 and AP-1. Thus, inhibition of NF-κB and AP-1 activation by [6]-SHO attenuates inflammation and cell proliferative response in DMBA induced hamsters. Our finding suggested that [6]-SHO is a novel functional agent capable of preventing DMBA induced inflammation and cell proliferation associated tumorigenesis by modulating multiple signalling molecules.

Antifibrotic effect of xanthohumol in combination with praziquantel is associated with altered redox status and reduced iron accumulation during liver fluke-associated cholangiocarcinogenesis

Cholangiocarcinoma (CCA) caused by infection of the liver fluke Opisthorchis viverrini, (Ov) is the major public health problem in northeast Thailand. Following Ov infection the subsequent molecular changes can be associated by reactive oxygen species (ROS) induced chronic inflammation, advanced periductal fibrosis, and cholangiocarcinogenesis. Notably, resistance to an activation of cell death in prolonged oxidative stress conditions can occur but some damaged/mutated cells could survive and enable clonal expansion. Our study used a natural product, xanthohumol (XN), which is an anti-oxidant and anti-inflammatory compound, to examine whether it could prevent Ov-associated CCA carcinogenesis. We measured the effect of XN with or without praziquantel (PZ), an anti-helminthic treatment, on DNA damage, redox status change including iron accumulation and periductal fibrosis during CCA genesis induced by administration of Ov and N-dinitrosomethylamine (NDMA) in hamsters. Animals were randomly divided into four groups: group I, Ov infection and NDMA administration (ON); group II, Ov infection and NDMA administration and PZ treatment (ONP); the latter 2 groups were similar to group I and II, but group III received additional XN (XON) and group IV received XN plus PZ (XONP). The results showed that high 8-oxodG (a marker of DNA damage) was observed throughout cholangiocarcinogenesis. Moreover, increased expression of CD44v8-10 (a cell surface in regulation of the ROS defense system), whereas decreased expression of phospho-p38^MAPK (a major ROS target), was found during the progression of the bile duct cell transformation. In addition, high accumulation of iron and expression of transferrin receptor-1 (TfR-1) in both malignant bile ducts and inflammatory cells were detected. Furthermore, fibrosis also increased with the highest level being on day 180. On the other hand, the groups of XN with or without PZ supplementations showed an effective reduction in all the markers examined, including fibrosis when compared with the ON group. In particular, the XONP group, in which a significant reduction DNA damage occurred, was also found to have iron accumulation and fibrosis compared to the other groups. Our results show that XN administered in combination with PZ could efficiently prevent CCA development and hence provide potential chemopreventive benefits in Ov-induced cholangiocarcinogenesis.

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.