Nutritional supplements, COX-2 and IGF-1 expression in men on active surveillance for prostate cancer

Effects of natural extract interventions in prostate cancer: A systematic review and network meta-analysis

BACKGROUND

Over years, there has been a widespread quest for effective dietary patterns and natural extracts to mitigate prostate cancer risk. However, despite numerous experimental studies conducted on various natural extracts, the evidence substantiating their efficacy remains largely insufficient. This dearth of compelling evidence presents a significant challenge in advocating for their widespread use as preventive measures against prostate cancer.

OBJECTIVE

Our study endeavors to undertake a network meta-analysis to evaluate the influence of natural extracts on prostate cancer.

METHODS

Researchers systematically searched through Embase, PubMed, Cochrane Library, and Web of Science databases until December 2023. The main focus was on assessing primary outcomes comprising prostate-specific antigen (PSA), insulin-like growth factor-binding protein-3 (IGFBP-3), insulin-like growth factor-1 (IGF-1). We conducted data analysis utilizing StataMP 15.0 software. Therapeutic effects were ranked based on the probability values derived from Surface Under the Cumulative Ranking curve (SUCRA). Additionally, cluster analysis was employed to assess the impacts of natural extracts on three distinct outcomes.

RESULTS

Following screening procedures, the 28 eligible studies were incorporated, the selected studies encompassed 1,566 prostate cancer patients and evaluated 16 different natural extract treatments. Specifically, 24 trials included PSA indicators, 10 included IGF-1 indicators, and 8 included IGFBP-3 indicators. The findings revealed that, based on the SUCRA values, the combined therapy of silybin with selenium (74%) appears to be the most effective approach for reducing serum PSA levels. Simultaneously, silybin alone (84.6%) stands out as the most promising option for decreasing serum IGF-1 levels. Lastly, concerning IGFBP-3, silybin alone (67.7%) emerges as the optimal choice. Twelve studies provided comprehensive information on adverse drug reactions/events (ADR/ADE), whereas five articles did not report any significant ADR/ADE.

CONCLUSION

The NMA suggests that, compared to placebo, utilizing silybin either alone or in combination with selenium has been shown to enhance therapeutic effects, offering potential benefits to patients with prostate cancer. This study can offer valuable insights for prostate patients considering natural extract treatments. Further evidence is required to confirm the safety profile of these treatments.

What Is the Role of Nutraceutical Products in Cancer Patients? A Systematic Review of Randomized Clinical Trials

Chemotherapy represents the main pharmacological cancer treatment. Recently, positive effects emerged with the combination of anticancer therapy and nutraceutical products. The aim of this systematic review is to collect and synthesize the available scientific evidence regarding the potential effects of nutraceuticals on cancer cells. A systematic literature search of randomized clinical trials of nutraceutical products in patients with cancer published up to 15 December 2022 was conducted using three data sources: Embase, PubMed, and Web of Science. The effect of high-dose isoflavone supplements on prostate cancer resulted in stabilization or reduction of PSA concentrations in 50% of isoflavone group patients six months after treatment. High doses of vitamin D supplementation plus chemotherapy in patients with advanced or metastatic colorectal cancer showed a median PFS of 13.0 months (95% CI, 10.1-14.7 months) for 49 patients. The effect of vitamin D supplementation on markers of inflammatory level and antioxidant capacity in women with breast cancer showed a significant increase in serum vitamin D concentration (28 ± 2.6 to 39 ± 3.5; p = 0.004) after 8 weeks of treatment. In conclusion, nutraceutical supplements represent a potentially growing sector and can be utilized in medical treatment or nutrition to provide integrated medical care.

The Anti-Cancer Activity of Lycopene: A Systematic Review of Human and Animal Studies

Lycopene is a nutraceutical with health-promoting and anti-cancer activities, but due to a lack of evidence, there are no recommendations regarding its use and dosage. This review aimed to evaluate the benefits of lycopene supplementation in cancer prevention and treatment based on the results of in vivo studies. We identified 72 human and animal studies that were then analysed for endpoints such as cancer incidence, improvement in treatment outcomes, and the mechanisms of lycopene action. We concluded that the results of most of the reviewed in vivo studies confirmed the anti-cancer activities of lycopene. Most of the studies concerned prostate cancer, reflecting the number of in vitro studies. The reported mechanisms of lycopene action in vivo included regulation of oxidative and inflammatory processes, induction of apoptosis, and inhibition of cell division, angiogenesis, and metastasis formation. The predominance of particular mechanisms seemed to depend on tumour organ localisation and the local storage capacity of lycopene. Finally, there is a need to look for predictive factors to identify a population that may benefit from lycopene supplementation. The potential candidates appear to be race, single nucleotide polymorphisms in carotene-cleaving enzymes, some genetic abbreviations, and insulin-like growth factor-dependent and inflammatory diseases.

Tomatoes: An Extensive Review of the Associated Health Impacts of Tomatoes and Factors That Can Affect Their Cultivation

Simple Summary

The research outlined in this review paper discusses potential health benefits associated with a diet enriched with tomatoes and tomato products. This includes details of previous studies investigating the anticancer properties of tomatoes, protection against cardiovascular and neurodegenerative diseases and diabetes, maintenance of a healthy gut microbiome, and improved skin health, fertility, immune response, and exercise recovery. The specific parts of a tomato fruit that contribute these health benefits are also outlined. The potential disadvantages to a tomato-rich diet are detailed, especially the consumption of supplements that contain compounds found in tomatoes, such as lycopene. This review also discusses how the cultivation of tomato plants can affect the nutritional value of the fruit harvested. Different environmental growing conditions such as light intensity, growing media, and temperature are explained in terms of the impact they have on the quality of fruit, its nutrient content, and hence the potential health benefits acquired from eating the fruit.

Abstract

This review outlines the health benefits associated with the regular consumption of tomatoes and tomato products. The first section provides a detailed account of the horticultural techniques that can impact the quality of the fruit and its nutritional properties, including water availability, light intensity, temperature, and growing media. The next section provides information on the components of tomato that are likely to contribute to its health effects. The review then details some of the health benefits associated with tomato consumption, including anticancer properties, cardiovascular and neurodegenerative diseases and skin health. This review also discusses the impact tomatoes can have on the gut microbiome and associated health benefits, including reducing the risk of inflammatory bowel diseases. Other health benefits of eating tomatoes are also discussed in relation to effects on diabetes, the immune response, exercise recovery, and fertility. Finally, this review also addresses the negative effects that can occur as a result of overconsumption of tomato products and lycopene supplements.

New Insights into Molecular Mechanism behind Anti-Cancer Activities of Lycopene

Lycopene is a well-known compound found commonly in tomatoes which brings wide range of health benefits against cardiovascular diseases and cancers. From an anti-cancer perspective, lycopene is often associated with reduced risk of prostate cancer and people often look for it as a dietary supplement which may help to prevent cancer. Previous scientific evidence exhibited that the anti-cancer activity of lycopene relies on its ability to suppress oncogene expressions and induce proapoptotic pathways. To further explore the real potential of lycopene in cancer prevention, this review discusses the new insights and perspectives on the anti-cancer activities of lycopene which could help to drive new direction for research. The relationship between inflammation and cancer is being highlighted, whereby lycopene suppresses cancer via resolution of inflammation are also discussed herein. The immune system was found to be a part of the anti-cancer system of lycopene as it modulates immune cells to suppress tumor growth and progression. Lycopene, which is under the family of carotenoids, was found to play special role in suppressing lung cancer.

Recent Progress in Discovering the Role of Carotenoids and Their Metabolites in Prostatic Physiology and Pathology with a Focus on Prostate Cancer-A Review-Part I: Molecular Mechanisms of Carotenoid Action

Among the vast variety of plant-derived phytochemicals, the group of carotenoids has continuously been investigated in order to optimize their potential application in the area of dietary intervention and medicine. One organ which has been especially targeted in many of these studies and clinical trials is the human prostate. Without doubt, carotenoids (and their endogenous derivatives—retinoids and other apo-carotenoids) are involved in intra- and intercellular signaling, cell growth and differentiation of prostate tissue. Due to the accumulation of new data on the role of different carotenoids such as lycopene (LC) and β-carotene (BC) in prostatic physiology and pathology, the present review aims to cover the past ten years of research in this area. Data from experimental studies are presented in the first part of the review, while epidemiological studies are disclosed and discussed in the second part. The objective of this compilation is to emphasize the present state of knowledge regarding the most potent molecular targets of carotenoids and their main metabolites, as well as to propose promising carotenoid agents for the prevention and treatment of prostatic diseases.

Dietary Factors and Prostate Cancer Development, Progression, and Reduction

Due to the constantly increasing number of cases, prostate cancer has become one of the most important health problems of modern societies. This review presents the current knowledge regarding the role of nutrients and foodstuff consumption in the etiology and development of prostate malignancies, including the potential mechanisms of action. The results of several in vivo and in vitro laboratory experiments as well as those reported by the clinical and epidemiological research studies carried out around the world were analyzed. The outcomes of these studies clearly show the influence of both nutrients and food products on the etiology and prevention of prostate cancer. Consumption of certain nutrients (saturated and trans fatty acids) and food products (e.g., processed meat products) leads to the disruption of prostate hormonal regulation, induction of oxidative stress and inflammation, and alteration of growth factor signaling and lipid metabolism, which all contribute to prostate carcinogenesis. On the other hand, a high consumption of vegetables, fruits, fish, and whole grain products exerts protective and/or therapeutic effects. Special bioactive functions are assigned to compounds such as flavonoids, stilbenes, and lycopene. Since the influence of nutrients and dietary pattern is a modifiable risk factor in the development and prevention of prostate cancer, awareness of the beneficial and harmful effects of individual food ingredients is of great importance in the global strategy against prostate cancer.

Lycopene Does Not Affect Prostate-Specific Antigen in Men with Non-Metastatic Prostate Cancer: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Several randomized controlled trials (RCTs) have investigated the effect of lycopene supplementation on serum levels of prostate-specific antigen (PSA) in patients with prostate cancer. However, results have been inconclusive. We systematically searched PubMed, Embase, and Scopus up to January 2020 to find RCTs investigating the effect of lycopene supplementation on serum levels of PSA in patients with non-metastatic prostate cancer. Using a random-effects model, the reported risk estimates were pooled. A total of six trials were included in the final analysis. we found no significant effect of lycopene on circulating PSA (WMD: -0.60, 95% CI: -2.01, 0.81 µg/L). However, we observed a significant reducing effect when the analysis was confined to studies that included patients with higher baseline levels of PSA (≥6.5 µg/L) (WMD: -3.74 µg/L, 95% CI: -5.15, -2.32, P < 0.001). Subgroup analysis based on the duration of intervention did not result in any significant effect. Non-linear dose-response analysis did not show any significant effects of lycopene dosage (P_{non-linearity} = 0.50) and duration of the intervention (P_{non-linearity} = 0.63) on serum levels of PSA. Although lycopene supplementation did not produce any reduction in PSA levels overall, a significant reducing effect was observed in patients with higher levels of baseline PSA. Due to the heterogeneity of our results, further high-quality clinical trials with long-term duration are required to determine the efficacy of lycopene in patients with non-metastatic prostate cancer.

Dietary Factors and Supplements Influencing Prostate Specific-Antigen (PSA) Concentrations in Men with Prostate Cancer and Increased Cancer Risk: An Evidence Analysis Review Based on Randomized Controlled Trials

The quest for dietary patterns and supplements efficient in down-regulating prostate-specific antigen (PSA) concentrations among men with prostate cancer (PCa) or increased PCa risk has been long. Several antioxidants, including lycopene, selenium, curcumin, coenzyme Q10, phytoestrogens (including isoflavones and flavonoids), green tea catechins, cernitin, vitamins (C, E, D) and multivitamins, medicinal mushrooms (Ganoderma lucidum), fruit extracts (saw palmetto, cranberries, pomegranate), walnuts and fatty acids, as well as combined supplementations of all, have been examined in randomized controlled trials (RCTs) in humans, on the primary, secondary, and tertiary PCa prevention level. Despite the plethora of trials and the variety of examined interventions, the evidence supporting the efficacy of most dietary factors appears inadequate to recommend their use.

A Scoping Review of Interactions between Omega-3 Long-Chain Polyunsaturated Fatty Acids and Genetic Variation in Relation to Cancer Risk

This scoping review examines the interaction of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and genetic variants of various types of cancers. A comprehensive search was performed to identify controlled and observational studies conducted through August 2017. Eighteen unique studies were included: breast cancer (n = 2), gastric cancer (n = 1), exocrine pancreatic cancer (n = 1), chronic lymphocytic leukemia (n = 1), prostate cancer (n = 7) and colorectal cancer (n = 6). An additional 13 studies that focused on fish intake or at-risk populations were summarized to increase readers’ understanding of the topic based on this review, DHA and EPA interact with certain genetic variants to decrease breast, colorectal and prostate cancer risk, although data was limited and identified polymorphisms were heterogeneous. The evidence to date demonstrates that omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) may decrease cancer risk by affecting genetic variants of inflammatory pathways, oxidative stress and tumor apoptosis. Collectively, data supports the notion that once a genetic variant is identified, the benefits of a targeted, personalized therapeutic regimen that includes DHA and/or EPA should be considered.

Effect of green tea and lycopene on the insulin-like growth factor system: the ProDiet randomized controlled trial

Whether prostate cancer (PCa) may be preventable by dietary interventions can be assessed in randomized trials using intermediate biomarkers of cancer risk or progression. We investigated whether lycopene or green tea modify circulating insulin-like growth factor (IGF) peptides in men at increased risk of PCa. Participants (aged 50-69 years) in one centre in the UK wide PCa testing and treatment trial (ProtecT) with prostate specific antigen between 2.0 and 2.95 ng/ml or negative biopsies, were randomized to daily lycopene (n = 44 assigned 15 mg capsules/day; 44 assigned a lycopene-rich diet; 45 assigned placebo) and green tea (n = 45 assigned 600 mg/day epigallocatechin gallate; 45 assigned green tea drink; 43 assigned placebo) for 6 months. The interventions significantly elevated the primary outcomes, serum epigallocatechin gallate and lycopene at 6 months of follow-up. We report here an exploratory analysis in which serum IGF-I, IGF-II, IGF binding protein (BP)-2 and IGFBP-3 were measured at baseline and 6 months of postintervention. A total of 133 men were randomized (34% of eligible men approached) and 130 had follow-up IGF peptides (98%). In intention-to-treat analyses, there was only weak evidence that lycopene or green tea influenced some aspects of serum IGF-I, IGF-II, IGFBP-2 or IGFBP-3. In men randomized to lycopene supplements, IGFBP-2 was nonsignificantly (50.9 ng/ml; 95% confidence interval: -51.2-152.9, P = 0.3) higher in comparison to placebo, whereas in men randomized to green tea supplements, IGFBP-3 was nonsignificantly (205.2 ng/ml; 95% confidence interval: -583.3-172.9, P = 0.3) lower than with placebo. In this small, pilot randomized controlled trial, there was little evidence that lycopene or green tea interventions influenced serum levels of IGF-I, IGF-II, IGFBBP-3 and IGFBP-2. However, the effects were imprecisely estimates and some observed trends may justify larger trials.

Omega-3 fatty acids decrease prostate cancer progression associated with an anti-tumor immune response in eugonadal and castrated mice

BACKGROUND

Several lines of evidence suggest effects of dietary fat on prostate cancer (PCa) development and progression. Targeting omega (ω)-3:ω6 fatty acids (FA) ratio could be beneficial against PCa by favorably modulating inflammation. Here, we studied the effects of ω3- and ω6-enriched diets on prostate tumor growth and inflammatory response in androgen-deprived and non-deprived conditions.

METHODS

Immune-competent eugonadal and castrated C57BL/6 mice were injected with TRAMP-C2 prostate tumor cells and daily fed with ω3- or ω6-enriched diet. FA and cytokine profiles were measured in blood and tumors using gas chromatography and multiplex immunoassay, respectively. Immune cell infiltration in tumors was profiled by multicolor flow cytometry.

RESULTS

ω3-enriched diet decreased prostate TRAMP-C2 tumor growth in immune-competent eugonadal and castrated mice. Cytokines associated with Th1 immune response (IL-12 [p70], IFN-γ, GM-CSF) and eosinophil recruitment (eotaxin-1, IL-5, and IL-13) were significantly elevated in tumors of ω3-fed mice. Using in vitro experiments, we confirmed ω3 FA-induced eotaxin-1 secretion by tumor cells and that eotaxin-1 secretion was regulated by androgens. Analysis of immune cell infiltrating tumors showed no major difference of immune cells' abundance between ω3- and ω6-enriched diets.

CONCLUSIONS

ω3-enriched diet reduces prostate tumor growth independently of androgen levels. ω3 FA can inhibit tumor cell growth and induce a local anti-tumor inflammatory response. These findings warrant further examination of dietary ω3's potential to slow down the progression of androgen-sensitive and castrate-resistant PCa by modulating immune cell function in tumors.

Critical Evaluation of Gene Expression Changes in Human Tissues in Response to Supplementation with Dietary Bioactive Compounds: Moving Towards Better-Quality Studies

Pre-clinical cell and animal nutrigenomic studies have long suggested the modulation of the transcription of multiple gene targets in cells and tissues as a potential molecular mechanism of action underlying the beneficial effects attributed to plant-derived bioactive compounds. To try to demonstrate these molecular effects in humans, a considerable number of clinical trials have now explored the changes in the expression levels of selected genes in various human cell and tissue samples following intervention with different dietary sources of bioactive compounds. In this review, we have compiled a total of 75 human studies exploring gene expression changes using quantitative reverse transcription PCR (RT-qPCR). We have critically appraised the study design and methodology used as well as the gene expression results reported. We herein pinpoint some of the main drawbacks and gaps in the experimental strategies applied, as well as the high interindividual variability of the results and the limited evidence supporting some of the investigated genes as potential responsive targets. We reinforce the need to apply normalized procedures and follow well-established methodological guidelines in future studies in order to achieve improved and reliable results that would allow for more relevant and biologically meaningful results.

Mechanisms of Phytonutrient Modulation of Cyclooxygenase-2 (COX-2) and Inflammation Related to Cancer

The link between chronic inflammation and cancer involves cytokines and mediators of inflammatory pathways. Cyclooxygenase-2 (COX-2), a key enzyme in fatty acid metabolism, is upregulated during both inflammation and cancer. COX-2 is induced by pro-inflammatory cytokines at the site of inflammation and enhanced COX-2-induced synthesis of prostaglandins stimulates cancer cell proliferation, promotes angiogenesis, inhibits apoptosis, and increases metastatic potential. As a result, COX-2 inhibitors are a subject of intense research interest toward potential clinical applications. Epidemiological studies highlight the potential benefits of diets rich in phytonutrients for cancer prevention. Plants contain numerous phytonutrient secondary metabolites shown to modulate COX-2. Studies have shown that these metabolites, some of which are used in traditional medicine, can reduce inflammation and carcinogenesis. This review describes the molecular mechanisms by which phytonutrients modulate inflammation, including studies of carotenoids, phenolic compounds, and fatty acids targeting various inflammation-related molecules and pathways associated with cancer. Examples of pathways include those of COX-2, mitogen-activated protein kinase kinase kinase, mitogen-activated protein kinase, pro-inflammatory cytokines, and transcription factors like nuclear factor kappa B. Such phytonutrient modulation of COX-2 and inflammation continue to be explored for applications in the prevention and treatment of cancer.

Long-chain n-3 PUFA against breast and prostate cancer: Which are the appropriate doses for intervention studies in animals and humans?

The potential antineoplastic effect of the long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) remains a highly controversial issue. Numerous animal studies have supported the anticancer role of these dietary fatty acids, whereas conflicting results have been obtained in population studies, and only a few intervention human trials have been so far performed. In view of the possibility that the anticancer effects may be maximally observed within a defined range of EPA and DHA doses, herein we critically review the results and doses used in both animal studies and human clinical trials focusing on the possible n-3 PUFA protective effects against breast and prostate cancer. Our main aim is to identify the EPA and/or DHA ranges of doses needed to obtain clear anticancer effects. This may be of great help in designing future animal studies, and also in understanding the most appropriate dose for further human intervention studies. Moreover, since the healthy effects of these fatty acids have been strictly related to their increased incorporation in plasma and tissue lipids, we also examine and discuss the incorporation changes following the administration of the effective anticancer EPA and/or DHA doses in animals and humans.

Association Between a Dietary Inflammatory Index and Prostate Cancer Risk in Ontario, Canada

BACKGROUND

Evidence exists showing that various aspects of diet are implicated in the etiology of prostate cancer, although results across studies remain inconsistent.

METHODS

We examined the ability of the dietary inflammatory index (DII) to predict prostate cancer in a case-control study conducted in Kingston, Ontario, Canada, between 1997 and 1999. The study included 72 cases of incident primary prostate cancer patients and 302 controls of urology clinic patients who had prostate conditions other than prostate cancer. The DII was computed based on intake of 18 nutrients assessed using a 67-item food frequency questionnaire. Univariate and multivariate logistic regression models were used to estimate odds ratios (ORs).

RESULTS

Men with higher DII scores were at increased risk of prostate cancer using DII score fit both as a continuous [OR = 1.58, 95% confidence interval (CI) 1.05-2.38] and categorical variable [compared to men in the lowest DII quartile, men in the highest quartile were at elevated risk (OR = 3.50, 95% CI 1.25-9.80; ptrend = 0.02)]. There was no significant heterogeneity by weight status, but stronger association was observed in men with body mass index >25 kg/m2 versus <25 kg/m2.

CONCLUSION

These findings suggest that a proinflammatory diet, as indicated by increasing DII score, is a risk factor for prostate cancer.

Fish-Derived Omega-3 Fatty Acids and Prostate Cancer: A Systematic Review

BACKGROUND

The use of natural health products in prostate cancer (PrCa) is high despite a lack of evidence with respect to safety and efficacy. Fish-derived omega-3 fatty acids possess anti-inflammatory effects and preclinical data suggest a protective effect on PrCa incidence and progression; however, human studies have yielded conflicting results.

METHODS

A search of OVID MEDLINE, Pre-MEDLINE, Embase, and the Allied and Complementary Medicine Database (AMED) was completed for human interventional or observational data assessing the safety and efficacy of fish-derived omega-3 fatty acids in the incidence and progression of PrCa.

RESULTS

Of 1776 citations screened, 54 publications reporting on 44 studies were included for review and analysis: 4 reports of 3 randomized controlled trials, 1 nonrandomized clinical trial, 20 reports of 14 cohort studies, 26 reports of 23 case-control studies, and 3 case-cohort studies. The interventional studies using fish oil supplements in patients with PrCa showed no impact on prostate-specific antigen levels; however, 2 studies showed a decrease in inflammatory or other cancer markers. A small number of mild adverse events were reported and interactions with other interventions were not assessed. Cohort and case-control studies assessing the relationship between dietary fish intake and the risk of PrCa were equivocal. Cohort studies assessing the risk of PrCa mortality suggested an association between higher intake of fish and decreased risk of prostate cancer-related death.

CONCLUSIONS

Current evidence is insufficient to suggest a relationship between fish-derived omega-3 fatty acid and risk of PrCa. An association between higher omega-3 intake and decreased PrCa mortality may be present but more research is needed. More intervention trials or observational studies with precisely measured exposure are needed to assess the impact of fish oil supplements and dietary fish-derived omega-3 fatty acid intake on safety, PrCa incidence, treatment, and progression.

Targeting arachidonic acid pathway by natural products for cancer prevention and therapy

Arachidonic acid (AA) pathway, a metabolic process, plays a key role in carcinogenesis. Hence, AA pathway metabolic enzymes phospholipase A₂s (PLA₂s), cyclooxygenases (COXs) and lipoxygenases (LOXs) and their metabolic products, such as prostaglandins and leukotrienes, have been considered novel preventive and therapeutic targets in cancer. Bioactive natural products are a good source for development of novel cancer preventive and therapeutic drugs, which have been widely used in clinical practice due to their safety profiles. AA pathway inhibitory natural products have been developed as chemopreventive and therapeutic agents against several cancers. Curcumin, resveratrol, apigenin, anthocyans, berberine, ellagic acid, eugenol, fisetin, ursolic acid, [6]-gingerol, guggulsteone, lycopene and genistein are well known cancer chemopreventive agents which act by targeting multiple pathways, including COX-2. Nordihydroguaiaretic acid and baicalein can be chemopreventive molecules against various cancers by inhibiting LOXs. Several PLA₂s inhibitory natural products have been identified with chemopreventive and therapeutic potentials against various cancers. In this review, we critically discuss the possible utility of natural products as preventive and therapeutic agents against various oncologic diseases, including prostate, pancreatic, lung, skin, gastric, oral, blood, head and neck, colorectal, liver, cervical and breast cancers, by targeting AA pathway. Further, the current status of clinical studies evaluating AA pathway inhibitory natural products in cancer is reviewed. In addition, various emerging issues, including bioavailability, toxicity and explorability of combination therapy, for the development of AA pathway inhibitory natural products as chemopreventive and therapeutic agents against human malignancy are also discussed.

Effect of Dietary Omega-3 Fatty Acids on Tumor-Associated Macrophages and Prostate Cancer Progression

BACKGROUND

Preclinical and clinical studies suggest that a fish oil-based diet may play a role in delaying the progression of prostate cancer through a number of different mechanisms involving inflammatory pathways. Given the importance of tumor-associated macrophages (TAMs) in carcinogenesis, we hypothesized that a fish oil-based diet will inhibit TAM infiltration and delay the growth of prostate cancer.

METHODS

Androgen sensitive mouse prostate cancer (MycCaP) allograft tumors were grown in fully immunocompetent FVB mice fed a high- fat fish oil (omega-3) or corn oil (omega-6) diet. Gene expression of markers for immune cell populations, cytokines, chemokines, and signaling pathways were determined by real-time PCR and western blot in tumor tissue. Cell proliferation and apoptosis in vitro were measured by MTS assay and flow cytometry.

RESULTS

Tumor volumes were significantly smaller in mice in ω-3 versus the ω-6 group (P = 0.048). Gene expression of markers for M1 and M2 macrophages (F4/80, iNOS, ARG1), associated cytokines (IL-6, TNF alpha, IL-10), and the chemokine CCL-2 were also lower in the omega-3 group. Correlative in vitro studies were performed in M1 and M2 polarized macrophages and mirrored the in vivo findings. Dietary fish oil and in vitro omega-3 fatty acid administration reduced protein expression of transcription factors in the nuclear factor kappa B pathway leading to a significant decrease in gene expression of downstream targets (Bcl-2, BCL-XL, XIAP, survivin) in MycCap cells.

CONCLUSIONS

These findings underscore the potential of fish oil in modulating the clinical course of human prostate cancer through the immune system. Further preclinical and clinical studies are warranted evaluating fish oil-based therapies for inhibiting the recruitment and function of M1 and M2 tumor infiltrating macrophages. Prostate 76:1293-1302, 2016. © 2016 Wiley Periodicals, Inc.

A Phase II Randomized Trial of Lycopene-Rich Tomato Extract Among Men with High-Grade Prostatic Intraepithelial Neoplasia

A diverse body of evidence suggests that lycopene might inhibit prostate cancer development. We conducted a 6-mo repeat biopsy randomized trial among men with high-grade prostatic intraepithelial neoplasia (HGPIN). Here we report results for serum lycopene, prostate specific antigen (PSA) and insulin-like growth factor (IGF) proteins, histopathological review, and tissue markers for proliferation [minichromosome maintenance protein 2 (MCM-2)] and cell cycle inhibition (p27). Participants consumed placebo or tomato extract capsules containing 30 mg/day lycopene. Pre- and posttreatment biopsies were immunostained and digitally scored. Serum lycopene was determined by LC-MS-MS. In secondary analyses, pathologists blindly reviewed each biopsy to score histological features. Fifty-eight men completed the trial. Serum lycopene increased 0.55 μmol/L with treatment and declined 0.29 μmol/L with placebo. We observed no meaningful differences in PSA, IGF-1, or IGF binding protein 3 concentrations between groups, nor any differences in expression of MCM-2 or p27 in epithelial nuclei. Prevalences of cancer, HGPIN, atrophy, or inflammation posttreatment were similar; however, more extensive atrophy and less extensive HGPIN was more common in the lycopene group. Despite large differences in serum lycopene following intervention, no treatment effects were apparent on either the serum or benign tissue endpoints. Larger studies are warranted to determine whether changes observed in extent of HGPIN and focal atrophy can be replicated.

ω-3 fatty acid differentially modulated serum levels of IGF1 and IGFBP3 in men with CVD: a randomized, double-blind placebo-controlled study

OBJECTIVE

Studies have reported elevated serum insulin-like growth factor (IGF)-1 levels followed by ω-3 supplementation in various groups. Considering decreased level of IGF1 in patients with cardiovascular disease (CVD) and protective effects of IGF1 against CVD progression and myocardial infarctions mortality, this study was performed with the aim of determining effects of ω-3 supplementation on serum levels and gene expression of IGF1 and IGF binding protein-3 (IGFBP3) in men with CVD.

METHODS

Sixty-two middle-aged (55.9 ± 6.5 y) non-obese men with CVD followed the study protocol in two groups of ω-3 (n = 31) or placebo (n = 31) supplementation. Participants took ω-3 supplement or placebo (edible paraffin) for 8 wk and were asked not to change their diet or physical activity plan. Anthropometric and lipid profile characteristics, serum IGF1, serum IGFBP3 and also IGF1 and IGFBP3 gene expression in peripheral blood mononuclear cells (PBMCs) were measured in all participants before and after the intervention. Statistical analyses were performed using SPSS software.

RESULTS

There were no significant differences between the two study groups in age and body mass index at baseline. The groups also had no difference in baseline serum low-density lipoprotein, high-density lipoprotein, very low-density lipoprotein, triacylglycerols, and IGF1. Compared with placebo, ω-3 supplementation increased serum IGF1 levels (P = 0.01), and decreased serum level of IGFBP3 (P = 0.02). There was a trending toward an increase in IGF1 expression and nonsignificant decrease in IGFBP3 expression.

CONCLUSIONS

ω-3 supplementation in patients with CVD increases serum IGF1 levels and decreases serum IGFBP3. Further research is warranted to investigate the underlying mechanisms.

Does active surveillance lead to anxiety and stress?

For men with prostate cancer (PC), patient care and treatment recommendations should not focus solely on the disease but should also take into account the views of the patient. The diagnosis and consequences of monitoring or treatment should be fully explained. Recommending Active Surveillance (AS) for the monitoring of a proven low-risk, low-volume prostate cancer should ensure that the psychological impact of AS is taken into account and included in a holistic approach to patient and disease management. This article is a rapid literature search relating to AS, and how the psychological impact of a cancer diagnosis may influence patient choice.

Prostatic and dietary omega-3 fatty acids and prostate cancer progression during active surveillance

The association between omega-3 (ω-3) fatty acids and prostate cancer has been widely studied. However, little is known about the impact of prostate tissue fatty acid content on prostate cancer progression. We hypothesized that compared with the estimated dietary ω-3 fatty acids intake and the ω-3 fatty acids levels measured in red blood cells (RBC), the prostate tissue ω-3 fatty acid content is more strongly related to prostate cancer progression. We present the initial observations from baseline data of a phase II clinical trial conducted in a cohort of 48 untreated men affected with low-risk prostate cancer, managed under active surveillance. These men underwent a first repeat biopsy session within 6 months after the initial diagnosis of low-risk prostate cancer, at which time 29% of the men had progressed from a Gleason score of 6 to a Gleason score of 7. At the first repeat biopsy session, fatty acid levels were assessed with a food-frequency questionnaire, and determined in the RBC and in the prostate tissue biopsy. We found that eicosapentaenoic acid (EPA) was associated with a reduced risk of prostate cancer progression when measured directly in the prostate tissue. Thus, this initial interim study analysis suggests that prostate tissue ω-3 fatty acids, especially EPA, may be protective against prostate cancer progression in men with low-risk prostate cancer.

Physical activity and prostate gene expression in men with low-risk prostate cancer

PURPOSE

Vigorous physical activity after diagnosis of localized prostate cancer may reduce the risk of disease progression and prostate cancer-specific mortality. The molecular mechanisms by which physical activity may exert protective effects in the prostate remain unknown.

METHODS

We examined the associations between self-reported physical activity and gene expression patterns in morphologically normal prostate tissue of 71 men with low-risk prostate cancer on active surveillance. Differential gene expression, gene set, and pathway analyses were conducted comparing dichotomous groups defined by type, intensity, and amount of physical activity reported.

RESULTS

Cell cycling and DNA repair pathways were up-regulated in men who participated in ≥ 3 h/week vigorous activity compared with men who did not. In addition, canonical pathways involved in cell signaling and metabolism, the cellular effects of sildenafil (Viagra), and the Nrf2-mediated oxidative stress response were modulated in men who reported ≥ 3 h/week of vigorous activity. Differential expression analysis at the individual gene level revealed modest differences between men who performed vigorous activity for ≥ 3 h/week and those who did not. There were no differences in prostate gene expression in comparisons with exercise groupings that did not consider both duration and intensity of activity.

CONCLUSIONS

Prostate gene expression and pathway analyses revealed sets of transcripts that may be modulated in normal prostate tissue by participating in ≥ 3 h/week of vigorous activity after diagnosis of low-risk prostate cancer. These findings suggest potential biological mechanisms by which vigorous activity may reduce risk of prostate cancer progression and warrant further study and validation.

Prostate cancer prevention: agent development strategies

Despite advances in surgery, radiation, and medical therapy over the past decade and the widespread adoption of PSA screening, prostate cancer continues to be the second leading cause of cancer death in men in the United States. Invasive cancer is the end result of carcinogenesis, a chronic process occurring over many years driven by genetic and epigenetic alterations. The protracted nature of this transformation to the malignant phenotype provides an opportunity to intervene pharmacologically to prevent, reverse, or delay carcinogenesis, i.e. chemoprevention. Herein, we describe the unique features of cancer prevention, as opposed to cancer treatment, agent development clinical trials, and provide a summary of the ongoing research in this field being supported by the National Cancer Institute.

Current evidence linking polyunsaturated Fatty acids with cancer risk and progression

There is increasing evidence that polyunsaturated fatty acids (PUFAs) play a role in cancer risk and progression. The n-3 family of PUFAs includes alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) while the n-6 family includes linolenic acid (LA) and arachidonic acid (AA). EPA and DHA are precursors for anti-inflammatory lipid mediators while AA is a precursor for pro-inflammatory lipid mediators. Collectively, PUFAs play crucial roles in maintaining cellular homeostasis, and perturbations in dietary intake or PUFA metabolism could result in cellular dysfunction and contribute to cancer risk and progression. Epidemiologic studies provide an inconsistent picture of the associations between dietary PUFAs and cancer. This discrepancy may reflect the difficulties in collecting accurate dietary data; however, it also may reflect genetic variation in PUFA metabolism which has been shown to modify physiological levels of PUFAs and cancer risk. Also, host-specific mutations as a result of cellular transformation could modify metabolism of PUFAs in the target-tissue. Clinical trials have shown that supplementation with PUFAs or foods high in PUFAs can affect markers of inflammation, immune function, tumor biology, and prognosis. Pre-clinical investigations have begun to elucidate how PUFAs may mediate cell proliferation, apoptosis and angiogenesis, and the signaling pathways involved in these processes. The purpose of this review is to summarize the current evidence linking PUFAs and their metabolites with cancer and the molecular mechanisms that underlie this association. Identifying the molecular mechanism(s) through which PUFAs affect cancer risk and progression will provide an opportunity to pursue focused dietary interventions that could translate into the development of personalized diets for cancer control.

The relevance of serum levels of long chain omega-3 polyunsaturated fatty acids and prostate cancer risk: A meta-analysis

OBJECTIVE

Our objective was to systematically analyze the evidence for an association between serum level long chain omega-3 polyunsaturated fatty acid (n-3 PUFA) and prostate cancer risk from human epidemiological studies. STUDY PROCEDURES: We searched biomedical literature databases up to November 2011 and included epidemiological studies with description of long chain n-3 PUFA and incidence of prostate cancer in humans. Critical appraisal was done by two independent reviewers. Data were pooled using the general variance-based method with random-effects model; effect estimates were expressed as risk ratio with 95% confidence interval (CI). Heterogeneity was assessed by Chi(2) and quantified by I(2), publication bias was also determined.

RESULTS

In total, 12 studies were included. Significant negative association was noted between high serum level of n-3 PUFA doc-osapentaenoic acid (DPA) and total prostate cancer risk (RR:0.756; 95% CI 0.599, 0.955; p = 0.019). Likewise, a positive association between high blood level of fish oil contents, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and high-grade prostate tumour incidence (RR:1.381; 95% CI 1.050, 1.817; p = 0.021) was noted; however, this finding was evident only after adjustment was done on interstudy variability through the removal of a lower quality study from the pool.

CONCLUSIONS

High serum levels of long chain n-3 PUFA DPA is associated with reduced total prostate cancer risk. While high blood level of EPA and DHA is possibly associated with increased high-grade prostate tumour risk.

Prostate cancer prevention: strategies for agent development

PURPOSE OF REVIEW

This article provides an update of clinical research supported by the National Cancer Institute's Phase I/II prostate cancer chemoprevention agent development program.

RECENT FINDINGS

Numerous clinical trials of pharmacologic interventions to delay, prevent or reverse carcinogenesis ('chemoprevention') with the ultimate goal of reducing cancer incidence have been conducted over the past decade. These trials range from relatively small, short-duration studies with biomarker endpoints to very large, long-term, general population trials with definitive cancer endpoints. Two large, population-based, Phase III prostate cancer prevention trials have shown a significant benefit for 5-α-reductase inhibitors. However, this class of agents was also associated with increased detection of high-grade prostate cancer. Another large, Phase III prostate cancer prevention trial showed no benefit for either selenium or vitamin E, given individually or in combination; in fact, a significant increase in prostate cancer was observed among men randomized to the vitamin E alone arm.

SUMMARY

A number of early phase trials and three definitive Phase III trials have been conducted in the field of prostate cancer prevention over the past decade. Although a great deal has been learned from these studies, significant work remains to be done to fully realize the potential of chemoprevention in this disease.

Low-fat diet with omega-3 fatty acids increases plasma insulin-like growth factor concentration in healthy postmenopausal women

The insulin-like growth factor pathway plays a central role in the normal and abnormal growth of tissues; however, nutritional determinants of insulin-like growth factor I (IGF-I) and its binding proteins in healthy individuals are not well defined. Three test diets-high-fat diet (40% energy as fat), low-fat diet (LF; 20% energy as fat), and a diet with low fat and high omega-3 fatty acid (LFn3; 23% energy as fat)--were tested in a randomized crossover designed controlled feeding trial in healthy postmenopausal women. Plasma IGF-I, IGF binding protein-3 (IGFBP-3), insulin, glucose, and ratio of IGF-I/IGFBP-3 concentrations were measured in response to diets. Insulin sensitivity was calculated using the homeostatic model assessment of insulin resistance We hypothesized that IGF-I, insulin, and glucose concentrations would decrease and IGFBP-3 concentration would increase in response to the low-fat diets. Eight weeks of the LFn3 diet increased circulating IGF-I (P < .001) and IGFBP-3 (P = .01) and the LF diet increased IGFBP-3 (P = .04), resulting in trends toward an increased IGF-I/IGFBP-3 ratio with the LFn3 diet and a decreased IGF-I/IGFBP-3 ratio with the LF diet (P = .13 for both comparisons). No statistically significant differences were detected between treatments at baseline or 8 weeks for IGF-1, IGFBP-3, or the ratio of IGF-1/IGFBP-3. Insulin, glucose, and the homeostatic model assessment of insulin resistance were not altered by the interventions. Low-fat diet with high n-3 fatty acids may increase circulating IGF-I concentrations without adversely affecting insulin sensitivity in healthy individuals.

Blood level omega-3 Fatty acids as risk determinant molecular biomarker for prostate cancer

Previous researches involving dietary methods have shown conflicting findings. Authors sought to assess the association of prostate cancer risk with blood levels of omega-3 polyunsaturated fatty acids (n-3 PUFA) through a meta-analysis of human epidemiological studies in available online databases (July, 2012). After critical appraisal by two independent reviewers, Newcastle-Ottawa Quality Assessment Scale (NOQAS) was used to grade the studies. Six case control and six nested case control studies were included. Results showed nonsignificant association of overall effect estimates with total or advanced prostate cancer or high-grade tumor. High blood level of alpha-linolenic acid (ALA) had nonsignificant positive association with total prostate cancer risk. High blood level of docosapentaenoic acid (DPA) had significant negative association with total prostate cancer risk. Specific n-3 PUFA in fish oil, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) had positive association with high-grade prostate tumor risk only after adjustment of interstudy variability. There is evidence that high blood level of DPA that is linked with reduced total prostate cancer risk and elevated blood levels of fish oils, EPA, and DHA is associated with high-grade prostate tumor, but careful interpretation is needed due to intricate details involved in prostate carcinogenesis and N-3 PUFA metabolism.

Dutasteride in localised prostate cancer management: the REDEEM randomised, double-blind, placebo-controlled trial

BACKGROUND

We aimed to investigate the safety and efficacy of dutasteride, a 5α-reductase inhibitor, on prostate cancer progression in men with low-risk disease who chose to be followed up with active surveillance.

METHODS

In our 3 year, randomised, double-blind, placebo-controlled study, undertaken at 65 academic medical centres or outpatient clinics in North America, we enrolled men aged 48-82 years who had low-volume, Gleason score 5-6 prostate cancer and had chosen to be followed up with active surveillance. We randomly allocated participants in a one-to-one ratio, stratified by site and in block sizes of four, to receive once-daily dutasteride 0·5 mg or matching placebo. Participants were followed up for 3 years, with 12-core prostate biopsy samples obtained after 18 months and 3 years. The primary endpoint was time to prostate cancer progression, defined as the number of days between the start of study treatment and the earlier of either pathological progression (in patients with ≥1 biopsy assessment after baseline) or therapeutic progression (start of medical therapy). This trial is registered with ClinicalTrials.gov, number NCT00363311.

FINDINGS

Between Aug 10, 2006, and March 26, 2007, we randomly allocated 302 participants, of whom 289 (96%) had at least one biopsy procedure after baseline and were included in the primary analysis. By 3 years, 54 (38%) of 144 men in the dutasteride group and 70 (48%) of 145 controls had prostate cancer progression (pathological or therapeutic; hazard ratio 0·62, 95% CI 0·43-0·89; p=0·009). Incidence of adverse events was much the same between treatment groups. 35 (24%) men in the dutasteride group and 23 (15%) controls had sexual adverse events or breast enlargement or tenderness. Eight (5%) men in the dutasteride group and seven (5%) controls had cardiovascular adverse events, but there were no prostate cancer-related deaths or instances of metastatic disease.

INTERPRETATION

Dutasteride could provide a beneficial adjunct to active surveillance for men with low-risk prostate cancer.

FUNDING

GlaxoSmithKline.

Phase II prospective randomized trial of a low-fat diet with fish oil supplementation in men undergoing radical prostatectomy

Preclinical studies suggest lowering dietary fat and decreasing the ratio of omega-6 to omega-3 polyunsaturated fatty acids decreases the risk of prostate cancer development and progression. We conducted a phase II randomized trial to test the effect of decreasing dietary fat combined with decreasing the dietary omega-6:omega-3 ratio on biomarkers related to prostate cancer development and progression. Patients undergoing radical prostatectomy were randomly assigned to receive a low-fat diet with 5 grams of fish oil daily (dietary omega-6:omega-3 ratio of 2:1) or a control Western diet (omega-6:omega-3 ratio of 15:1) for four to six weeks prior to surgery. The primary endpoint was change in serum insulin-like growth factor I (IGF-1) between arms. Secondary endpoints were serum IGFBP-1, prostate prostaglandin E2 levels, omega-6:omega-3 fatty acid ratios, COX-2, and markers of proliferation and apoptosis. Fifty-five patients were randomized and 48 completed the trial. There was no treatment difference in the primary outcome. Positive secondary outcomes in the low-fat fish oil versus Western group were reduced benign and malignant prostate tissue omega-6:omega-3 ratios, reduced proliferation (Ki-67 index), and reduced proliferation in an ex vivo bioassay when patient sera was applied to prostate cancer cells in vitro. In summary, four to six weeks of a low-fat diet and fish oil capsules to achieve an omega-6:omega-3 fatty acid ratio of 2:1 had no effect on serum IGF-1 levels, though in secondary analyses, the intervention resulted in decreased prostate cancer proliferation and decreased prostate tissue omega-6:omega-3 ratios. These results support further studies evaluating reduction of dietary fat with fish oil supplementation on modulating prostate cancer biology.

Gene expression and biological pathways in tissue of men with prostate cancer in a randomized clinical trial of lycopene and fish oil supplementation

Background

Studies suggest that micronutrients may modify the risk or delay progression of prostate cancer; however, the molecular mechanisms involved are poorly understood. We examined the effects of lycopene and fish oil on prostate gene expression in a double-blind placebo-controlled randomized clinical trial.

Methods

Eighty-four men with low risk prostate cancer were stratified based on self-reported dietary consumption of fish and tomatoes and then randomly assigned to a 3-month intervention of lycopene (n = 29) or fish oil (n = 27) supplementation or placebo (n = 28). Gene expression in morphologically normal prostate tissue was studied at baseline and at 3 months via cDNA microarray analysis. Differential gene expression and pathway analyses were performed to identify genes and pathways modulated by these micronutrients.

Results

Global gene expression analysis revealed no significant individual genes that were associated with high intake of fish or tomato at baseline or after 3 months of supplementation with lycopene or fish oil. However, exploratory pathway analyses of rank-ordered genes (based on p-values not corrected for multiple comparisons) revealed the modulation of androgen and estrogen metabolism in men who routinely consumed more fish (p = 0.029) and tomato (p = 0.008) compared to men who ate less. In addition, modulation of arachidonic acid metabolism (p = 0.01) was observed after 3 months of fish oil supplementation compared with the placebo group; and modulation of nuclear factor (erythroid derived-2) factor 2 or Nrf2-mediated oxidative stress response for either supplement versus placebo (fish oil: p = 0.01, lycopene: p = 0.001).

Conclusions

We did not detect significant individual genes associated with dietary intake and supplementation of lycopene and fish oil. However, exploratory analyses revealed candidate in vivo pathways that may be modulated by these micronutrients.

Trial Registration

ClinicalTrials.gov NCT00402285

Vegetable and fruit intake after diagnosis and risk of prostate cancer progression

Cruciferous vegetables, tomato sauce and legumes have been associated with reduced risk of incident advanced prostate cancer. In vitro and animal studies suggest these foods may inhibit progression of prostate cancer, but there are limited data in men. Therefore, we prospectively examined whether intake of total vegetables, and specifically cruciferous vegetables, tomato sauce and legumes, after diagnosis reduce risk of prostate cancer progression among 1,560 men diagnosed with non-metastatic prostate cancer and participating in the Cancer of the Prostate Strategic Urologic Research Endeavor, a United States prostate cancer registry. As a secondary analysis, we also examined other vegetable subgroups, total fruit and subgroups of fruits. The participants were diagnosed primarily at community-based clinics and followed from 2004 to 2009. We assessed vegetable and fruit intake via a semi-quantitative food frequency questionnaire, and ascertained prostate cancer outcomes via urologist report and medical records. We observed 134 events of progression (53 biochemical recurrences, 71 secondary treatments likely due to recurrence, 6 bone metastases and 4 prostate cancer deaths) during 3,171 person-years. Men in the fourth quartile of post-diagnostic cruciferous vegetable intake had a statistically significant 59% decreased risk of prostate cancer progression compared to men in the lowest quartile (hazard ratio (HR): 0.41; 95% confidence interval (CI): 0.22, 0.76; p-trend: 0.003). No other vegetable or fruit group was statistically significantly associated with risk of prostate cancer progression. In conclusion, cruciferous vegetable intake after diagnosis may reduce risk of prostate cancer progression.

Molecular markers that can be utilized in diet and dietary supplement research

Prostate and other cancers have a multitude of potential markers that can be used in laboratory and clinical studies of diet and dietary supplement interventions. More overt clinical markers include imaging tests, biopsy samples, prostate-specific antigen kinetics, and urinary testing. Many molecular markers are currently available, including antiapoptotic and apoptotic proteins, cell adhesion molecules, cell cycle compounds, growth factors, angiogenic markers, and proliferative and inflammatory signals. Protein kinases and transcription factors should also be considered for diversity. Testing of numerous molecular markers has become critical in gaining preliminary insight into the potential impact of a novel diet and supplemental agents.