An update on chemoprevention strategies in prostate cancer for 2006

Phase II randomised control feasibility trial of a nutrition and physical activity intervention after radical prostatectomy for prostate cancer

OBJECTIVE

Dietary factors and physical activity may alter prostate cancer progression. We explored the feasibility of lifestyle interventions following radical prostatectomy for localised prostate cancer.

DESIGN

Patients were recruited into a presurgical observational cohort; following radical prostatectomy, they were offered randomisation into a 2×3 factorial randomised controlled trial (RCT).

SETTING

A single National Health Service trust in the South West of England, UK.

PARTICIPANTS

Those with localised prostate cancer and listed for radical prostatectomy were invited to participate.

RANDOMISATION

Random allocation was performed by the Bristol Randomised Trial Collaboration via an online system.

INTERVENTIONS

Men were randomised into both a modified nutrition group (either increased vegetable and fruit, and reduced dairy milk; or lycopene supplementation; or control) and a physical activity group (brisk walking or control) for 6 months.

BLINDING

Only the trial statistician was blind to allocations.

PRIMARY OUTCOME MEASURES

Primary outcomes were measures of feasibility: randomisation rates and intervention adherence at 6 months. Collected at trial baseline, three and six months, with daily adherence reported throughout. Our intended adherence rate was 75% or above, the threshold for acceptable adherence was 90%.

RESULTS

108 men entered the presurgical cohort, and 81 were randomised into the postsurgical RCT (randomisation rate: 93.1%) and 75 completed the trial. Of 25 men in the nutrition intervention, 10 (40.0%; 95% CI 23.4% to 59.3%) adhered to the fruit and vegetable recommendations and 18 (72.0%; 95% CI 52.4% to 85.7%) to reduced dairy intake. Adherence to lycopene (n=28), was 78.6% (95% CI 60.5% to 89.8%), while 21/39 adhered to the walking intervention (53.8%; 95% CI 38.6% to 68.4%). Most men were followed up at 6 months (75/81; 92.6%). Three 'possibly related' adverse events were indigestion, abdominal bloating and knee pain.

CONCLUSIONS

Interventions were deemed feasible, with high randomisation rates and generally good adherence. A definitive RCT is proposed.

TRIAL REGISTRATION NUMBER

ISRCTN 99048944.

Detection of candidate biomarkers of prostate cancer progression in serum: a depletion-free 3D LC/MS quantitative proteomics pilot study

BACKGROUND

Prostate cancer (PCa) is the most common male cancer in the United Kingdom and we aimed to identify clinically relevant biomarkers corresponding to stage progression of the disease.

METHODS

We used enhanced proteomic profiling of PCa progression using iTRAQ 3D LC mass spectrometry on high-quality serum samples to identify biomarkers of PCa.

RESULTS

We identified >1000 proteins. Following specific inclusion/exclusion criteria we targeted seven proteins of which two were validated by ELISA and six potentially interacted forming an 'interactome' with only a single protein linking each marker. This network also includes accepted cancer markers, such as TNF, STAT3, NF-κB and IL6.

CONCLUSIONS

Our linked and interrelated biomarker network highlights the potential utility of six of our seven markers as a panel for diagnosing PCa and, critically, in determining the stage of the disease. Our validation analysis of the MS-identified proteins found that SAA alongside KLK3 may improve categorisation of PCa than by KLK3 alone, and that TSR1, although not significant in this model, might also be a clinically relevant biomarker.

Prostate cancer - evidence of exercise and nutrition trial (PrEvENT): study protocol for a randomised controlled feasibility trial

Background

A growing body of observational evidence suggests that nutritional and physical activity interventions are associated with beneficial outcomes for men with prostate cancer, including brisk walking, lycopene intake, increased fruit and vegetable intake and reduced dairy consumption. However, randomised controlled trial data are limited. The ‘Prostate Cancer: Evidence of Exercise and Nutrition Trial’ investigates the feasibility of recruiting and randomising men diagnosed with localised prostate cancer and eligible for radical prostatectomy to interventions that modify nutrition and physical activity. The primary outcomes are randomisation rates and adherence to the interventions at 6 months following randomisation. The secondary outcomes are intervention tolerability, trial retention, change in prostate specific antigen level, change in diet, change in general physical activity levels, insulin-like growth factor levels, and a range of related outcomes, including quality of life measures.

Methods/design

The trial is factorial, randomising men to both a physical activity (brisk walking or control) and nutritional (lycopene supplementation or increased fruit and vegetables with reduced dairy consumption or control) intervention. The trial has two phases: men are enrolled into a cohort study prior to radical prostatectomy, and then consented after radical prostatectomy into a randomised controlled trial. Data are collected at four time points (cohort baseline, true trial baseline and 3 and 6 months post-randomisation).

Discussion

The Prostate Cancer: Evidence of Exercise and Nutrition Trial aims to determine whether men with localised prostate cancer who are scheduled for radical prostatectomy can be recruited into a cohort and subsequently randomised to a 6-month nutrition and physical activity intervention trial. If successful, this feasibility trial will inform a larger trial to investigate whether this population will gain clinical benefit from long-term nutritional and physical activity interventions post-surgery.

Prostate Cancer: Evidence of Exercise and Nutrition Trial (PrEvENT) is registered on the ISRCTN registry, ref number ISRCTN99048944. Date of registration 17 November 2014.

n-3 Polyunsaturated Fatty Acids and their Role in Cancer Chemoprevention

Polyunsaturated fatty acids (PUFAs), including omega-3 (n-3) and omega-6 (n-6) PUFAs, are essential for human health. Recent research shows n-3 PUFAs and their mediators can inhibit inflammation, angiogenesis and cancer via multiple mechanisms, including reduced release of n-6 fatty acid arachidonic acid from cell membranes, inhibition of enzymatic activities, and direct competition with arachidonic acid for enzymatic conversions. In this review, we discuss inflammation-related cancer, anti-inflammatory effects of n-3 PUFA lipid mediators, antineoplastic activities of n-3 PUFA in vitro and in vivo, and present an update on recent human trials.

A whole-genome SNP association study of NCI60 cell line panel indicates a role of Ca2+ signaling in selenium resistance

Epidemiological studies have suggested an association between selenium intake and protection from a variety of cancer. Considering this clinical importance of selenium, we aimed to identify the genes associated with resistance to selenium treatment. We have applied a previous methodology developed by our group, which is based on the genetic and pharmacological data publicly available for the NCI60 cancer cell line panel. In short, we have categorized the NCI60 cell lines as selenium resistant and sensitive based on their growth inhibition (GI50) data. Then, we have utilized the Affymetrix 125K SNP chip data available and carried out a genome-wide case-control association study for the selenium sensitive and resistant NCI60 cell lines. Our results showed statistically significant association of four SNPs in 5q33–34, 10q11.2, 10q22.3 and 14q13.1 with selenium resistance. These SNPs were located in introns of the genes encoding for a kinase-scaffolding protein (AKAP6), a membrane protein (SGCD), a channel protein (KCNMA1), and a protein kinase (PRKG1). The knock-down of KCNMA1 by siRNA showed increased sensitivity to selenium in both LNCaP and PC3 cell lines. Furthermore, SNP-SNP interaction (epistasis) analysis indicated the interactions of the SNPs in AKAP6 with SGCD as well as SNPs in AKAP6 with KCNMA1 with each other, assuming additive genetic model. These genes were also all involved in the Ca²⁺ signaling, which has a direct role in induction of apoptosis and induction of apoptosis in tumor cells is consistent with the chemopreventive action of selenium. Once our findings are further validated, this knowledge can be translated into clinics where individuals who can benefit from the chemopreventive characteristics of the selenium supplementation will be easily identified using a simple DNA analysis.

On the combined effect of statins and lycopene on cytokine production by human peripheral blood cells

Since both statins and lycopene exert immunomodulatory activities following incubation with human peripheral blood mononuclear cells (PBMC), the present work was designed to examine whether they may induce a synergistic or antagonistic effect on cytokine production while applied together. Peripheral blood mononuclear cells isolated from 15 healthy subjects were incubated for 24 h as follows: (1) without and with 0.125 or 0.25 microM lycopene, (2) without and with 10 or 50 mM pravastatin or simvastatin, and (3) with lycopene and with one of the statins together at the respective doses. The production of the following cytokines was assessed: interleukin (IL)-1beta, IL-1ra, IL-2, and IL-10, as well as tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma). The results showed that lycopene and simvastatin applied together reduced TNFalpha and IFNgamma secretion, and abolished the increased production of the proinflammatory cytokine IL-1gamma caused by incubation with simvastatin only, an observation suggesting that simultaneous administration of both substances may reduce inflammatory responses.

Herbal extract of Wedelia chinensis attenuates androgen receptor activity and orthotopic growth of prostate cancer in nude mice

PURPOSE

Wedelia chinensis is a common ingredient of anti-inflammatory herbal medicines in Taiwan and southern China. Inflammation is involved in promoting tumor growth, invasion, and metastasis. This study aims to test the biological effects in vivo of W. chinensis extract on prostate cancer.

EXPERIMENTAL DESIGN

The in vivo efficacy and mechanisms of action of oral administration of a standardized extract of W. chinensis were analyzed in animals bearing a subcutaneous or orthotopic prostate cancer xenograft.

RESULTS

Exposure of prostate cancer cells to W. chinensis extract induced apoptosis selectively in androgen receptor (AR)-positive prostate cancer cells and shifted the proportion in each phase of cell cycle toward G(2)-M phase in AR-negative prostate cancer cells. Oral herbal extract (4 or 40 mg/kg/d for 24-28 days) attenuated the growth of prostate tumors in nude mice implanted at both subcutaneous (31% and 44%, respectively) and orthotopic (49% and 49%, respectively) sites. The tumor suppression effects were associated with increased apoptosis and lower proliferation in tumor cells as well as reduced tumor angiogenesis. The antitumor effect of W. chinensis extract was correlated with accumulation of the principle active compounds wedelolactone, luteolin, and apigenin in vivo.

CONCLUSION

Anticancer action of W. chinensis extract was due to three active compounds that inhibit the AR signaling pathway. Oral administration of W. chinensis extract impeded prostate cancer tumorigenesis. Future studies of W. chinensis for chemoprevention or complementary medicine against prostate cancer in humans are thus warranted.

Suppression of NFkappaB and its regulated gene products by oral administration of green tea polyphenols in an autochthonous mouse prostate cancer model

PURPOSE

This study examines the role of cell survival/apoptosis related proteins involved in NFkappaB signaling pathways and its associated events in GTP-induced chemoprevention of prostate cancer in TRAMP mice.

METHODS

Mice were given 0.1% GTP as drinking fluid. Western blot and immunohistochemical analysis performed to examine NFkappaB and its regulated pathway in response to GTP.

RESULTS

Our data demonstrated increased expression of NFkappaB, IKKalpha, IKKbeta, RANK, NIK and STAT-3 in dorso-lateral prostate of TRAMP mice as a function of age and tumor growth and continuous GTP infusion for 32 weeks resulted in substantial reduction in these proteins. The levels of transcription factor osteopontin, a non-collagenous extracellular matrix protein, were also downregulated. Inhibition of NFkappaB signaling is known to activate apoptotic and inhibit anti-apoptotic proteins. Therefore, we analyzed Bax and Bcl2 levels in the dorsolateral prostate of TRAMP mice fed GTP and observed a shift in balance between Bax and Bcl2 favoring apoptosis.

CONCLUSIONS

Based on the data we suggest that oral consumption of GTP might inhibit osteopontin and NFkappaB signaling that may contribute to induction of apoptosis observed in GTP fed TRAMP mice.

Significance of chemoprevention for prostate cancer development: experimental in vivo approaches to chemoprevention

Prostate cancer is the most common tumor in men in Western countries and mortality in Asian countries from the disease appears to be constantly increasing. Characteristics include (i) frequent discovery of latent carcinoma, even in countries with low incidences of clinical cancer; (ii) very long time to clinically significant cancer; (iii) few patients under 50 years of age (primarily a disease of elderly men); (iv) strong influences of environmental factors such as food; (v) temporal effectiveness of androgen deprival therapy; and (vi) no effective therapeutic approaches once hormone-refractory neoplasms have developed. Therefore prostate cancer is particularly indicated for preventive efforts, especially chemoprevention. Several large-scale chemoprevention trials have in fact been conducted and some have found suppressive effects. However, not all have been proven to have benefit. Experimental preclinical investigations, particularly using animal models, are recommended to find better chemopreventive agents with less adverse effects. Data using rat models have generated very interesting findings from which mechanism-based strategies can be proposed. In the present report the importance of chemoprevention of prostate cancer will be discussed using the data on human and rat prostate cancer development.

Tea or coffee? A case study on evidence for dietary advice

The present paper explores the level of evidence required to justify giving dietary advice to the public. There are important practical differences between the development of public health nutrition guidelines and guidelines for clinical practice. While the gold standard for evidence for clinical practice guidelines is a meta-analysis of a number of randomised controlled trials, this is often unrealistic and sometimes unethical for the evaluation of public health nutrition interventions. Hence, epidemiological studies make up the bulk of evidence for nutrition guidelines. Tea and coffee are an interesting case study in relation to this issue. They are two of the most commonly consumed beverages worldwide, yet there is little dietary advice on their use. The evidence for a relationship between coffee or tea consumption and several diseases is discussed. The available studies, predominantly epidemiological, together with animal and in vitro studies, indicate that coffee and tea are both safe beverages. However, tea is the healthier option because it has a possible role in the prevention of several cancers and CVD. While the evidence for such relationships is not strong, the public will continue to drink both tea and coffee, and will continue to ask nutritionists to make recommendations. It is therefore argued that advice should be given on the best available data, as waiting for complete data to become available could have severe consequences for public health.

Statin use and risk of prostate cancer in the California Men's Health Study cohort

Statins have known anticarcinogenic effects, however, evidence for long-term statin use as effective chemoprevention for prostate cancer is inconsistent. We examined the association between statin use and risk of prostate cancer among 69,047 eligible participants in the California Men's Health Study, a prospective cohort of Northern and Southern California Kaiser Permanente (KP) members, ages 45 to 69 years, initiated in 2002. Prostate cancer cases were identified by linkage to the KP California Cancer Registries. Statin exposure, estimated from automated KP outpatient pharmacy records (available since 1991 in Southern California and since 1994 in Northern California), was treated as time-varying and defined as the cumulative days dispensed of any statin from the first dispensing until a prostate cancer diagnosis, radical prostatectomy, termination of membership, or end of study (December 31, 2004). Cox proportional hazards models with age as the time scale were used to estimate rate ratios, while controlling for confounding variables. During follow-up, 888 prostate cancer cases, including 131 advanced cases, were identified. There was no association between ever statin use or <5 years use and prostate cancer. Conversely, >or=5 years use was associated with a 28% lower risk for prostate cancer compared with nonuse (adjusted rate ratio, 0.72; 95% confidence interval, 0.53-0.99). This association did not differ markedly for advanced disease. However, the association did seem to be restricted to those who regularly take nonsteroidal anti-inflammatory drugs. Our findings suggest that long-term statin use might be associated with a reduced risk of prostate cancer but perhaps only among regular nonsteroidal anti-inflammatory drug users.

Selenium activates p53 and p38 pathways and induces caspase-independent cell death in cervical cancer cells

The mechanisms of sodium selenite-induced cell death in cervical carcinoma cells were studied during 24 h of exposure in the HeLa Hep-2 cell line. Selenite at the employed concentrations of 5 and 50 micromol/L produced time- and dose-dependent suppression of DNA synthesis and induced DNA damage which resulted in phosphorylation of histone H2A.X. These effects were influenced by pretreatment of cells with the SOD/catalase mimetic MnTMPyP or glutathione-depleting buthionine sulfoximine, suggesting the significant role of selenite-generated oxidative stress. Following the DNA damage, selenite activated p53-dependent pathway as evidenced by the appearance of phosphorylated p53 and accumulation of p21 in the treated cells. Concomitantly, selenite activated p38 pathway but its effect on JNK was very weak. p53- and p38-dependent signaling led to the accumulation of Bax protein, which was preventable by specific inhibitors of p38 (SB 203580) and p53 (Pifithrin-alpha). Mitochondria in selenite-treated cells changed their dynamics (shape and localization) and released AIF and Smac/Diablo, which initiated caspase-independent apoptosis as confirmed by the caspase-3 activity assay and the low effect of caspase inhibitors z-DEVD-fmk and z-VAD-fmk on cell death. We conclude that selenite induces caspase-independent apoptosis in cervical carcinoma cells mostly by oxidative stress-mediated activation of p53 and p38 pathways, but other selenite-mediated effects, in particular mitochondria-specific ones, are also involved.

Inflammation in prostate carcinogenesis

About 20% of all human cancers are caused by chronic infection or chronic inflammatory states. Recently, a new hypothesis has been proposed for prostate carcinogenesis. It proposes that exposure to environmental factors such as infectious agents and dietary carcinogens, and hormonal imbalances lead to injury of the prostate and to the development of chronic inflammation and regenerative 'risk factor' lesions, referred to as proliferative inflammatory atrophy (PIA). By developing new experimental animal models coupled with classical epidemiological studies, genetic epidemiological studies and molecular pathological approaches, we should be able to determine whether prostate cancer is driven by inflammation, and if so, to develop new strategies to prevent the disease.