Diet, nutrition, and prostate cancer

The Risk Factors and Screening Uptake for Prostate Cancer: A Scoping Review

OBJECTIVES

The purpose of this scoping review was to identify the risk factors and screening uptake for prostate cancer.

DESIGN

Scoping review.

METHODS

Arksey and O'Malley's framework guided this review; five databases (Cumulative Index to Nursing and Allied Health Literature (CINAHL), MEDLINE, PsycINFO, Academic Search Complete and Cochrane Library) and grey literature were searched. Screening was undertaken against predetermined inclusion criteria for articles published before July 2023 and written in English. This review is reported in line with PRISMA-Sc.

RESULTS

10,899 database results were identified; 3676 papers were removed as duplicates and 7115 papers were excluded at title and abstract review. A total of 108 papers were full-text reviewed and 67 were included in the review. Grey literature searching yielded no results. Age, family history/genetics, hormones, race/ethnicity, exposure to hazards, geographical location and diet were identified as risk factors. Prostatic antigen test (PSA), digital rectal examination (DRE), transrectal ultrasound (TRUS), magnetic resonance imaging (MRI), magnetic resonance spectroscopic imaging (MRSI) and prostate biopsy were identified as screening/diagnostic methods. The evidence reviewed highlights moderate knowledge and screening uptake of prostate cancer with less than half of men reporting for PSA screening. On the other hand, there is a year-to-year increase in PSA and DRE screening, but factors such as poverty, religion, culture, communication barriers, language and costs affect men's uptake of prostate cancer screening.

CONCLUSION

As prostate cancer rates increase globally, there is a need for greater uptake of prostate cancer screening and improved health literacy among men and health workers. There is a need to develop a comprehensive prostate cancer awareness and screening programme that targets men and addresses uptake issues so as to provide safe, quality care.

STRENGTHS AND LIMITATIONS OF THIS STUDY

(1) A broad search strategy was utilised incorporating both databases and grey literature. (2) The PRISMA reporting guidelines were utilised. (3) Only English language papers were included, and this may have resulted in relevant articles being omitted.

Insufficient Lycopene Intake Is Associated With High Risk of Prostate Cancer: A Cross-Sectional Study From the National Health and Nutrition Examination Survey (2003-2010)

Although lycopene intake and risk of prostate cancer have been explored for decades, recent studies show that Non-Hispanic Black Prostate Cancer (PCa) patients benefit less than Non-Hispanic White patients from a lycopene intake intervention program. This study examined whether a lycopene intake-related racial disparity exists in reducing the risk of PCa in healthy adults. Data on healthy, cancer-free Non-Hispanic Black (NHB) men (n = 159) and Non-Hispanic White (NHW) men (n = 478) from the 2003 to 2010 NHANES dataset were analyzed. Total lycopene intake from daily diet, age, living status, race/ethnicity, education level, poverty income ratio, body mass index, and smoking status were studied as independent variables. The combination of total Prostate-Specific Antigen (PSA) level and the ratio of free PSA was set as criteria for evaluating the risk of PCa. Multivariable logistic regression was used in race-stratified analyses to compute odds ratios (OR) and 95% confidence intervals (95% CI) comparing high PCa risk with low PCa risk. We found, in the whole population, race/ethnicity was the only factor that influenced lycopene intake from the daily diet. NHB men consumed less lycopene than NHW men (3,716 vs. 6,487 (mcg), p = 0.01). Sufficient lycopene intake could reduce the risk of PCa (OR: 0.40, 95% CI: 0.18-0.85, p = 0.02). Men aged between 66 and 70 had high PCa risk (OR: 3.32, 95% CI: 1.12-9.85, p = 0.03). Obesity served as a protective factor against the high risk of PCa (OR: 0.25, 95% CI: 0.12-0.54, p = 0.001). NHW men aged between 66 and 70 had a high risk of PCa (OR: 4.01, 95% CI: 1.02-15.73, p = 0.05). Obese NHW men also had lower risk of PCa (OR: 0.18, 95% CI: 0.07-0.47 p = 0.001). NHB men had a high risk of PCa compared to NHW men (OR: 2.27, 95% CI: 1.35-3.81 p = 0.004). NHB men who were living without partners experienced an even higher risk of PCa (OR: 3.35, 95% CI: 1.01-11.19 p = 0.07). Sufficient lycopene intake from daily food could serve as a protector against PCa. Such an association was only observed in NHW men. Further studies are needed to explore the dose-response relationship between lycopene intake and the association of PCa risk in NHB men.

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.

Roles of endogenous ether lipids and associated PUFAs in the regulation of ion channels and their relevance for disease

Ether lipids (ELs) are lipids characterized by the presence of either an ether linkage (alkyl lipids) or a vinyl ether linkage [i.e., plasmalogens (Pls)] at the sn1 position of the glycerol backbone, and they are enriched in PUFAs at the sn2 position. In this review, we highlight that ELs have various biological functions, act as a reservoir for second messengers (such as PUFAs) and have roles in many diseases. Some of the biological effects of ELs may be associated with their ability to regulate ion channels that control excitation-contraction/secretion/mobility coupling and therefore cell physiology. These channels are embedded in lipid membranes, and lipids can regulate their activities directly or indirectly as second messengers or by incorporating into membranes. Interestingly, ELs and EL-derived PUFAs have been reported to play a key role in several pathologies, including neurological disorders, cardiovascular diseases, and cancers. Investigations leading to a better understanding of their mechanisms of action in pathologies have opened a new field in cancer research. In summary, newly identified lipid regulators of ion channels, such as ELs and PUFAs, may represent valuable targets to improve disease diagnosis and advance the development of new therapeutic strategies for managing a range of diseases and conditions.

Structure and function of the calcium-selective TRP channel TRPV6

Epithelial calcium channel TRPV6 is a member of the vanilloid subfamily of TRP channels that is permeable to cations and highly selective to Ca²⁺ ; it shows constitutive activity regulated negatively by Ca²⁺ and positively by phosphoinositol and cholesterol lipids. In this review, we describe the molecular structure of TRPV6 and discuss how its structural elements define its unique functional properties. High Ca²⁺ selectivity of TRPV6 originates from the narrow selectivity filter, where Ca²⁺ ions are directly coordinated by a ring of anionic aspartate side chains. Divalent cations Ca²⁺ and Ba²⁺ permeate TRPV6 pore according to the knock-off mechanism, while tight binding of Gd³⁺ to the aspartate ring blocks the channel and prevents Na⁺ from permeating the pore. The iris-like channel opening is accompanied by an α-to-π helical transition in the pore-lining transmembrane helix S6. As a result of this transition, the intracellular halves of the S6 helices bend and rotate by about 100 deg, exposing different residues to the channel pore in the open and closed states. Channel opening is also associated with changes in occupancy of the transmembrane domain lipid binding sites. The inhibitor 2-aminoethoxydiphenyl borate (2-APB) binds to TRPV6 in a pocket formed by the cytoplasmic half of the S1-S4 transmembrane helical bundle and shifts open-closed channel equilibrium towards the closed state by outcompeting lipids critical for activation. Ca²⁺ inhibits TRPV6 via binding to calmodulin (CaM), which mediates Ca²⁺ -dependent inactivation. The TRPV6-CaM complex exhibits 1:1 stoichiometry; one TRPV6 tetramer binds both CaM lobes, which adopt a distinct head-to-tail arrangement. The CaM C-terminal lobe plugs the channel through a unique cation-π interaction by inserting the side chain of lysine K115 into a tetra-tryptophan cage at the ion channel pore intracellular entrance. Recent studies of TRPV6 structure and function described in this review advance our understanding of the role of this channel in physiology and pathophysiology and inform new therapeutic design.

α-Casein Changes Gene Expression Profiles and Promotes Tumorigenesis of Prostate Cancer Cells

Prostate cancer is among the most prevalent malignancies in men. High intake of dairy products is associated with an increased risk of prostate cancer. No study has examined the gene profile changes and molecular mechanism by which casein, milk protein, affects prostate cancer cells. In this study, we used gene expression profiling to identify gene changes in PC3 prostate cancer cells exposed to α-casein. α-casein altered the expression of a large number of genes-related prostate cancer, transcription factor, apoptotic, metabolic, and cell cycle pathways, in addition to the expected cell proliferation signaling pathways. To clarify the molecular events involved in the effect of α-casein on proliferation and progression of PC3 cells, we examined cell proliferation assay, quantitative real-time PCR, Western blotting, and immunohistochemical and immunofluorescence staining. α-casein promoted PC3 cell proliferation and survival under serum-free conditions by increasing the expression of E2F1 and its target gene PCNA. α-casein also protected PC3 cells from serum-starved autophagic cell death by activating the PI3K/Akt pathway through activation of mTORC1, up-regulation of p70S6K, and down-regulation of LC3 autophagosome formation. Our data provide new insights into the molecular mechanisms underlying the tumorigenic effect of α-casein in prostate cancer cells.

Muscadine grape skin extract inhibits prostate cancer cells by inducing cell-cycle arrest, and decreasing migration through heat shock protein 40

Previously we demonstrated that muscadine grape skin extract (MSKE), a natural product, significantly inhibited androgen-responsive prostate cancer cell growth by inducing apoptosis through the targeting of survival pathways. However, the therapeutic effect of MSKE on more aggressive androgen-independent prostate cancer remains unknown. This study examined the effects of MSKE treatment in metastatic prostate cancer using complementary PC-3 cells and xenograft model. MSKE significantly inhibited PC-3 human prostate cancer cell tumor growth in vitro and in vivo. The growth-inhibitory effect of MSKE appeared to be through the induction of cell-cycle arrest. This induction was accompanied by a reduction in the protein expression of Hsp40 and cell-cycle regulation proteins, cyclin D1 and NF-kBp65. In addition, MSKE induced p21 expression independent of wild-type p53 induced protein expression. Moreover, we demonstrate that MSKE significantly inhibited cell migration in PC-3 prostate cancer cells. Overall, these results demonstrate that MSKE inhibits prostate tumor growth and migration, and induces cell-cycle arrest by targeting Hsp40 and proteins involved in cell-cycle regulation and proliferation. This suggests that MSKE may also be explored either as a neo-adjuvant or therapeutic for castration resistant prostate cancer.

DHPLC Elution Patterns of VDR PCR Products Can Predict Prostate Cancer Susceptibility in African American Men

BACKGROUND/AIM

Denaturing high-performance liquid chromatography (DHPLC) is a technique that is used to detect mutations. The aim of the present study was to determine whether DHPLC elution patterns of vitamin D receptor (VDR) gene PCR products can serve as indicators of susceptibility to prostate cancer (PCa) risk.

MATERIALS AND METHODS

DNA samples of PCa cases and controls were screened for mutations and/or polymorphisms in coding exons of VDR gene using DHPLC analysis. Logistic regression, phi-coefficient (ϕ), and Backward Wald models were used to analyze the data.

RESULTS

Similar elution patterns of exons 1, 6, 7 and 9 along with higher prevalence of heteroduplex DNA were observed in PCa samples than in controls. Exons 4 and 8 had highly significant protective effects (p<0.05). Whereas, exons 5, 7, and 9 were perfectly positively correlated with PCa risk (ϕ=1), thus presenting candidate exons significantly associated with susceptibility to PCa.

CONCLUSION

DHPLC elution patterns of the selected exons could be useful to predict susceptibility to develop PCa.

Dietary tomato and lycopene impact androgen signaling- and carcinogenesis-related gene expression during early TRAMP prostate carcinogenesis

Consumption of tomato products containing the carotenoid lycopene is associated with a reduced risk of prostate cancer. To identify gene expression patterns associated with early testosterone-driven prostate carcinogenesis, which are impacted by dietary tomato and lycopene, wild-type (WT) and transgenic adenocarcinoma of the mouse prostate (TRAMP) mice were fed control or tomato- or lycopene-containing diets from 4 to 10 weeks of age. Eight-week-old mice underwent sham surgery, castration, or castration followed by testosterone repletion (2.5 mg/kg/d initiated 1 week after castration). Ten-week-old intact TRAMP mice exhibit early multifocal prostatic intraepithelial neoplasia. Of the 200 prostate cancer-related genes measured by quantitative NanoString, 189 are detectable, 164 significantly differ by genotype, 179 by testosterone status, and 30 by diet type (P < 0.05). In TRAMP, expression of Birc5, Mki67, Aurkb, Ccnb2, Foxm1, and Ccne2 is greater compared with WT and is decreased by castration. In parallel, castration reduces Ki67-positive staining (P < 0.0001) compared with intact and testosterone-repleted TRAMP mice. Expression of genes involved in androgen metabolism/signaling pathways is reduced by lycopene feeding (Srd5a1) and by tomato feeding (Srd5a2, Pxn, and Srebf1). In addition, tomato feeding significantly reduced expression of genes associated with stem cell features, Aldh1a and Ly6a, whereas lycopene feeding significantly reduced expression of neuroendocrine differentiation-related genes, Ngfr and Syp. Collectively, these studies demonstrate a profile of testosterone-regulated genes associated with early prostate carcinogenesis that are potential mechanistic targets of dietary tomato components. Future studies on androgen signaling/metabolism, stem cell features, and neuroendocrine differentiation pathways may elucidate the mechanisms by which dietary tomato and lycopene impact prostate cancer risk.

Associations of nm23H1, VEGF-C, and VEGF-3 receptor in human prostate cancer

We studied the expression of the non-metastatic clone 23 type 1 (nm23H1) gene, vascular endothelial growth factor (VEGF)-C, and its receptor VEGFR-3 using an in situ hybridization technique and immunohistochemical analyses with prostate cancer tissues and adjacent benign tissues of 52 human archival cases. The association between VEGF-C expression, microlymphatic count (MLC), and staining intensity for nm23H1 and VEGFR-3 was used to evaluate tumor metastasis and survival rate. MLC values were significantly higher in tumorous tissue than in non-cancerous tissue. VEGF-C mRNA, VEGFR-3, and nm23H1 were highly expressed in tumorous tissue. VEGFR-3 expression was greater in VEGF-C mRNA-positive tumors than in VEGF-C mRNA-negative tumors. The association of VEGFR-3 expression with VEGF-C mRNA and MLC suggested that the poor prognosis and tumor metastasis associated with VEGFR-3 expression may be due, in part, to its role in promoting angiogenesis. VEGF-C expression was significantly associated with tumor lymphangiogenesis, angiogenesis, and immune response as a potent multifunctional stimulating factor in prostate cancer. Expression of nm23H1 was significantly inversely correlated with lymph node metastasis. Furthermore, there was a strong negative correlation between the expression of nm23H1, VEGF-C mRNA, and MLC. These findings provide important information for prophylactic, diagnostic, and therapeutic strategies for prostate cancer.

Dietary patterns as predictors of prostate cancer in Jamaican men

Studies of diet and prostate cancer have focused primarily on food and nutrients; however, dietary patterns examine the overall diet, particularly foods eaten in combination, and risk of disease. We evaluated the association of dietary patterns and prostate cancer and low- and high-grade subgroups in Jamaican men. In a case-control study, we enrolled 243 incident cases and 273 urology controls in Jamaican clinics, March 2005-July 2007. Dietary patterns were identified using principal component analysis. Four food patterns were identified: a "vegetable and legume" pattern, a "fast food" pattern, a "meat" pattern, and a "refined carbohydrate" pattern. Men in the highest tertile for the refined carbohydrate pattern, characterized by high intakes of rice, pasta, sugar sweetened beverages, and sweet baked foods were at increased risk of total prostate cancer [odds ratio (OR) = 2.02; 95% confidence interval (CI) = 1.05-3.87 (Ptrend = 0.029)] and low-grade disease [OR = 2.91; 95% CI = 1.18-7.13 (Ptrend = 0.019)] compared with men in the lowest tertile. The vegetable and legumes pattern (healthy), meat pattern, or fast food pattern were not associated with prostate cancer risk. These data suggest a carbohydrate dietary pattern high in refined carbohydrates may be a risk factor for prostate cancer in Jamaican men.

Fish oil slows prostate cancer xenograft growth relative to other dietary fats and is associated with decreased mitochondrial and insulin pathway gene expression

Background

Previous mouse studies suggest that decreasing dietary fat content can slow prostate cancer (PCa) growth. To our knowledge, no study has yet compared the effect of multiple different fats on PCa progression. We sought to systematically compare the effect of fish oil, olive oil, corn oil, and animal fat on PCa progression.

Methods

A total of 96 male SCID mice were injected with LAPC-4 human PCa cells. Two weeks following injection, mice were randomized to a fish oil, olive oil, corn oil, or animal fat-based Western diet (35% kcals from fat). Animals were euthanized when tumors reached 1,000mm³. Serum was collected at sacrifice and assayed for PSA, insulin, IGF-1, IGFBP-3, and PGE-2 levels. Tumors were also assayed for PGE-2 and COX-2 levels and global gene expression analyzed using Affymetrix microarrays.

Results

Mice weights and tumor volumes were equivalent across groups at randomization. Overall, fish oil consumption was associated with improved survival, relative to other dietary groups (p=0.014). On gene expression analyses, the fish oil group had decreased signal in pathways related to mitochondrial physiology and insulin synthesis/secretion.

Conclusions

In this xenograft model, we found that consuming a diet in which fish oil was the only fat source slowed tumor growth and improved survival, compared to mice consuming diets composed of olive oil, corn oil, or animal fat. While prior studies showed that the amount of fat is important for PCa growth, the current study suggests that type of dietary fat consumed may also be important.

Endogenous n-3 polyunsaturated fatty acids delay progression of pancreatic ductal adenocarcinoma in Fat-1-p48(Cre/+)-LSL-Kras(G12D/+) mice

Preclinical studies suggest that diets rich in omega-3 polyunsaturated fatty acids (n-3 PUFAs) may be beneficial for prevention of pancreatic cancer. Nutritional intervention studies are often complex, and there is no clear evidence, without potential confounding factors, on whether conversion of n-6 PUFAs to n-3 PUFAs in pancreatic tissues would provide protection. Experiments were designed using n-3 fatty acid desaturase (Fat-1) transgenic mice, which can convert n-6 PUFA to n-3 FAs endogenously, to determine the impact of n-3 PUFAs on pancreatic intraepithelial neoplasms (PanINs) and their progression to pancreatic ductal adenocarcinoma (PDAC). Six-week-old female p48(Cre/+)-LSL-Kras(G12D/+) and compound Fat-1-p48(Cre/+)-LSL-Kras(G12D/+) mice were fed (AIN-76A) diets containing 10% safflower oil for 35 weeks. Pancreata were evaluated histopathologically for PanINs and PDAC. Results showed a dramatic reduction in incidence of PDAC (84%; P < .02) in Fat-1-p48(Cre/+)-LSL-Kras(G12D/+) mice compared to p48(Cre/+)-LSL-Kras(G12D/+) mice. Importantly, significant reductions of pancreatic ducts with carcinoma (90%; P < .0001) and PanIN 3 (~50%; P < .001) lesions were observed in the compound transgenic mice. The levels of n-3 PUFA were much higher (>85%; P < .05-0.01) in pancreas of compound transgenic mice than in those of p48(Cre/+)-LSL-Kras(G12D/+) mice. Molecular analysis of the pancreas showed a significant down-regulation of proliferating cell nuclear antigen, cyclooxygenase-2, 5-lipoxygenase (5-LOX), 5-LOX-activating protein, Bcl-2, and cyclin D1 expression levels in Fat-1-p48(Cre/+)-LSL-Kras(G12D/+) mice compared to p48(Cre/+)-LSL-Kras(G12D/+) mice. These data highlight the promise of dietary n-3 FAs for chemoprevention of pancreatic cancer in high-risk individuals.

Intake of grains and dietary fiber and prostate cancer aggressiveness by race

Purpose. To examine the associations among intake of refined grains, whole grains and dietary fiber and aggressiveness of prostate cancer in African Americans (AA, n = 930) and European Americans (EA, n = 993) in a population-based, case-only study (The North Carolina-Louisiana Prostate Cancer Project, PCaP). Methods. Prostate cancer aggressiveness was categorized as high, intermediate or low based on Gleason grade, PSA level and clinical stage. Dietary intake was assessed utilizing the NCI Diet History Questionnaire. Logistic regression (comparing high to intermediate/low aggressive cancers) and polytomous regression with adjustment for potential confounders were used to determine odds of high prostate cancer aggressiveness with intake of refined grains, whole grains and dietary fiber from all sources. Results. An inverse association with aggressive prostate cancer was observed in the 2nd and 3rd tertiles of total fiber intake (OR = 0.70; 95% CI, 0.50–0.97 and OR = 0.61; 95% CI, 0.40–0.93, resp.) as compared to the lowest tertile of intake. In the race-stratified analyses, inverse associations were observed in the 3rd tertile of total fiber intake for EA (OR = 0.44; 95% CI, 0.23–0.87) and the 2nd tertile of intake for AA (OR = 0.57; 95% CI, 0.35–0.95). Conclusions. Dietary fiber intake was inversely associated with aggressive prostate cancer among both AA and EA men.

A novel measure of dietary change in a prostate cancer dietary program incorporating mindfulness training

Diet may represent a modifiable prostate cancer risk factor, but a vegetable-based prostate-healthy diet is a major change for most men. We used a ratio of animal to vegetable proteins (A:V) to evaluate whether a comprehensive dietary change was self-sustaining following completion of 11 weekly dietary and cooking classes that integrated mindfulness training. Thirty-six men with recurring prostate cancer were randomized to the intervention or wait-list control. Assessments were at baseline, 3 months, and 6 months. Of 17 men randomized to the intervention, 14 completed the requirements. Nineteen were randomized to control and 17 completed requirements. Compared with controls, a significant postintervention (3 months) decrease in A:V in the intervention group (P=0.01) was self-maintained 3 months postintervention (P=0.049). At each assessment, A:V was correlated with lycopene, fiber, saturated fat, and dietary cholesterol, four dietary components linked to clinically relevant outcomes in prostate cancer. Change in A:V was also significantly correlated with changes in fiber, saturated fat, and dietary cholesterol intake. Participants reported regular mindfulness training practice, and there was a significant correlation between mindfulness training practice and changes in both initiation and maintenance of the change in A:V. These pilot results provide encouraging evidence for the feasibility of a dietary program that includes mindfulness training in supporting dietary change for men with recurrent prostate cancer and invite further study to explore the possible role of mindfulness training as a means of supporting both initiation of dietary changes and maintenance of those changes over time.

Fat-1 transgenic cattle as a model to study the function of ω-3 fatty acids

ω-3 polyunsaturated fatty acids have been shown to play an important role in health. Enriched with ω-3 polyunsaturated fatty acids modulate expression of a number of genes with such broad functions as cell proliferation, growth and apoptosis and cell signaling and transduction, these effects, seem to regulate coronary artery disease, hypertension, atherosclerosis, psychiatric disorders and various cancer. In this context, fat-1 transgenic cattle was designed to convert ω-6 to ω-3 fatty acids could form an ideal model to study the effect of ω-3 fatty acids on the above functions. This study focuses on the total genomic difference of gene expression between fat-1 transgenic cattle and wild-type using cDNA microarrays, several genes were found to be overexpressed or suppressed in transgenic cattle relative to wild-type, these discrepancy genes related with lipid metabolism, immunity, inflammation nervous development and fertility.

Impact of XPD gene polymorphism on risk of prostate cancer on north Indian population

Prostate cancer is the second most diagnosed cancer in men next to skin cancer in the developed world. Risk of disease varies most prominently with age, ethnicity, family history, and diet. Genetic polymorphism of some genes has been implicated in increasing the risk. The XPD (Xeroderma pigmentosum group D) gene codes for a DNA helicase involved in transcription and nucleotide excision repair. The aim of this study is to evaluate the effect of XPD 751 Lys/Gln polymorphism on risk of prostate cancer on north Indian patients. Blood sample from 150 prostate cancer patients, 150 from Prostate Hyper Plasia and equal number of samples from healthy control groups was collected from North India. The polymerase chain reaction and restrictive fragment length polymorphism techniques were implemented. Statistically non-significant increase risk of prostate cancer was observed with patients having Gln/Gln genotype (OR 1.62, 95% CI).

Chemical inhibitors of the calcium entry channel TRPV6

PURPOSE

Calcium entry channels in the plasma membrane are thought to play a major role in maintaining cellular Ca(2+) levels, crucial for growth and survival of normal and cancer cells. The calcium-selective channel TRPV6 is expressed in prostate, breast, and other cancer cells. Its expression coincides with cancer progression, suggesting that it drives cancer cell growth. However, no specific inhibitors for TRPV6 have been identified thus far.

METHODS

To develop specific TRPV6 inhibitors, we synthesized molecules based on the lead compound TH-1177, reported to inhibit calcium entry channels in prostate cancer cells in vitro and in vivo.

RESULTS

We found that one of our compounds (#03) selectively inhibited TRPV6 over five times better than TRPV5, whereas TH-1177 and the other synthesized compounds preferentially inhibited TRPV5. The IC(50) value for growth inhibition by blocking endogenous Ca(2+) entry channels in the LNCaP human prostate cancer cell line was 0.44 ± 0.07 μM compared to TH-1177 (50 ± 0.4 μM).

CONCLUSIONS

These results suggest that compound #03 is a relatively selective and potent inhibitor for TRPV6 and that it is an interesting lead compound for the treatment of prostate cancer and other cancers of epithelial origin.

Diet and prostate cancer risk with specific focus on dairy products and dietary calcium: a case-control study

BACKGROUND

Despite the prevalence of prostate cancer worldwide, only a few risk factors have been well-established. The role of diet, especially of dairy products, in the etiology of prostate cancer is still controversial.

METHODS

This study assessed the association of dietary components, particularly dairy products and dietary calcium, on prostate cancer risk in a case-control study of 197 cases and an equal number of individually matched controls recruited in Montreal, Canada. A semi-quantitative food frequency questionnaire was administered in which the usual consumption frequency and amounts consumed of more than 200 food items were recorded.

RESULTS

We found a twofold increased risk of prostate cancer associated with an increased intake of dairy products {Odds Ratio (OR) = 2.19; 95% Confidence Intervals (CI) 1.22-3.94}. A significant trend of decreasing prostate cancer risk with higher intake was found for legumes, nuts, finfish/shellfish and for alpha-tocopherol after adjustment for calcium intake. Milk was the only dairy product significantly associated with prostate cancer risk, with OR = 2.27; 95% CI (1.25-4.09) for the highest versus lowest quartiles of consumption. Calcium, the main micronutrient contained in dairy products, showed only a borderline association with prostate cancer risk (P = 0.09), with slightly higher risk for higher calcium intake. In conclusion, this study supports the hypothesis that dairy products, especially milk, are involved in the etiology of prostate cancer. However, the mechanisms by which the various nutrients in dairy products and total diet may interact to influence this risk remain unknown.

Plasma organochlorine levels and prostate cancer risk

A case-control study was conducted to determine the association between plasma organochlorine levels and prostate cancer risk. Male clinic patients scheduled for prostate core biopsy or seeing their urologist for other conditions from 1997 through 1999 in Kingston, Ontario were eligible, excluding those with an earlier cancer. Age frequency matched controls (n=329) were compared with 79 incident prostate cancer cases. Before knowledge of diagnosis, the patients completed a questionnaire and donated 15 ml of blood for the measurement of 14 PCBs, and 13 organochlorine pesticides by gas chromatography. At least 70% of patients had detectable levels of nine PCB congeners and seven pesticides, and these chemicals were included in the risk analysis adjusted for total lipids. Geometric means for these PCB congeners, total PCBs, and p,p'-DDE are slightly lower for cases than controls, whereas the levels of p,p'-DDT and other pesticides are virtually equal. Adjusting for age and other confounders in multivariable logistic regression, odds ratios (ORs) are consistently below 1.0 for PCB congeners and total PCBs. For pesticides, most ORs are very close to the null. This study suggests that long-term low-level exposure to organochlorine pesticides and PCBs in the general population does not contribute to increased prostate cancer risk.

Effect of isocaloric low fat diet on prostate cancer xenograft progression in a hormone deprivation model

PURPOSE

Previous mouse studies suggesting that low fat diets slow prostate cancer growth often used corn oil (omega-6), which enhances prostate cancer growth, as the primary fat. Using a saturated fat based diet we previously found no significant difference in tumor growth between low and high fat fed SCID mice (Taconic Farms, Hudson, New York) xenografted with LAPC-4 cells. Whether similar results would hold in a castration model is unclear.

MATERIALS AND METHODS

A total of 80 male SCID mice were fed a Western diet (40% fat and 44% carbohydrate) and injected with LAPC-4 human prostate cancer cells. When tumors were 200 mm(3), the mice were castrated and randomized to an isocaloric Western or a low fat diet (12% fat and 72% carbohydrate). Animals were sacrificed when tumors were 1,000 mm(3). Serum was collected and assayed for prostate specific antigen, insulin, insulin-like growth factor 1 and insulin-like growth factor binding protein 3. Tumors were assayed for total and phosphorylated Akt.

RESULTS

Mouse weight was equivalent in the 2 groups. Overall dietary group was not significantly associated with survival (log rank p = 0.32). There were no statistically significant differences in prostate specific antigen (p = 0.53), insulin-like growth factor axis parameters (each p >0.05) or p-Akt-to-t-Akt ratios (p = 0.22) between the groups at sacrifice.

CONCLUSIONS

In this xenograft model we found no difference in tumor growth or survival between low fat vs Western fed mice when the fat source was saturated fat. These results conflict with those of other studies in which corn oil was used to show that low fat diets delay prostate cancer growth, suggesting that fat type may be as important as fat amount in the prostate cancer setting.

Inositol hexaphosphate downregulates both constitutive and ligand-induced mitogenic and cell survival signaling, and causes caspase-mediated apoptotic death of human prostate carcinoma PC-3 cells

Constitutively active mitogenic and prosurvival signaling cascades due to aberrant expression and interaction of growth factors and their receptors are well documented in human prostate cancer (PCa). Epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1) are potent mitogens that regulate proliferation and survival of PCa cells via autocrine and paracrine loops involving both mitogen-activated protein kinase (MAPK)- and Akt-mediated signaling. Accordingly, here we assessed the effect of inositol hexaphosphate (IP6) on constitutive and ligand (EGF and IGF-1)-induced biological responses and associated signaling cascades in advanced and androgen-independent human PCa PC-3 cells. Treatment of PC-3 cells with 2 mM IP6 strongly inhibited both growth and proliferation and decreased cell viability; similar effects were also observed in other human PCa DU145 and LNCaP cells. IP6 also caused a strong apoptotic death of PC-3 cells together with caspase 3 and PARP cleavage. Mechanistic studies showed that biological effects of IP6 were associated with inhibition of both constitutive and ligand-induced Akt phosphorylation together with a decrease in total Akt levels, but a differential inhibitory effect on MAPKs extra cellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal protein kinase (JNK1/2), and p38 under constitutive and ligand-activated conditions. Under similar condition, IP6 also inhibited AP-1 DNA-binding activity and decreased nuclear levels of both phospho and total c-Fos and c-Jun. Together, these findings for the first time establish IP6 efficacy in inhibiting aberrant EGF receptor (EGFR) or IGF-1 receptor (IGF-1R) pathway-mediated sustained growth promoting and survival signaling cascades in advanced and androgen-independent human PCa PC-3 cells, which might have translational implications in advanced human PCa control and management.

Regulation of cell survival by resveratrol involves inhibition of NF kappa B-regulated gene expression in prostate cancer cells

BACKGROUND

Polyphenols have been proposed as antitumoral agents. We have shown that resveratrol (RES) induced cell cycle arrest and promoted apoptosis in prostate cancer cells by inhibition of the PI3K pathway. The RES effects on NF kappaB activity in LNCaP cells (inducible NF kappaB), and PC-3 cells (constitutive NF kappaB) are reported.

METHODS

Cells were treated with 1-150 microM of RES during 36 hr. NF kappaB subcellular localization was analyzed by western blot and immunofluorescence. I kappaB alpha was evaluated by immunoprecipitation followed by Western blot. Specific DNA binding of NF kappaB was determined by EMSA assays and NF kappaB-mediated transcriptional activity by transient transfection with a luciferase gene reporter system.

RESULTS

RES induced a dose-dependent cytoplasmic retention of NF kappaB mediated by I kappaB alpha in PC-3 cells but not in LNCaP. RES-induced inhibition of NF kappaB specific binding to DNA was more significant in PC-3 cells. NF kappaB-mediated transcriptional activity induced by EGF and TNFalpha were inhibited by RES in both cell lines. LY294002 mimicked RES effects on NF kappaB activity.

CONCLUSION

Antiproliferative and apoptotic effects of RES on human prostate cancer cells may be mediated by the inhibition of NF kappaB activity. This mechanism seems to be associated to RES-induced PI3K inhibition. RES could have therapeutic potential for prostate cancer treatment.

Induction of cell cycle arrest in prostate cancer cells by the dietary compound isoliquiritigenin

Isoliquiritigenin (ISL), a flavonoid chalcone that is present in licorice, shallot, and bean sprouts, is known to have antitumorigenic activities. The present study examined whether ISL alters prostate cancer cell cycle progression. DU145 human and MatLyLu (MLL) rat prostate cancer cells were cultured with various concentrations of ISL. In both DU145 and MLL cells treated with ISL, the percentage of cells in the G1 phase increased, and the incorporation of [(3)H]thymidine decreased. ISL decreased the protein levels of cyclin D1, cyclin E, and cyclin-dependent kinase (CDK) 4, whereas cyclin A and CDK2 expressions were unaltered in cells treated with ISL. The expression of the CDK inhibitor p27(KIP1) was increased in cells treated with 20 micromol/L ISL. In addition, treatment of cells with 20 micromol/L ISL for 24 hours led to G2/M cell cycle arrest. Cell division control (CDC) 2 protein levels remained unchanged. The protein levels of phospho-CDC2 (Tyr15) and cyclin B1 were increased, and the CDC25C level was decreased by ISL dose-dependently. We demonstrate that ISL promotes cell cycle arrest in DU145 and MLL cells, thereby providing insights into the mechanisms underlying its antitumorigenic activities.

Green tea polyphenols inhibit testosterone production in rat Leydig cells

This study investigated the acute effects of green tea extract (GTE) and its polyphenol constituents, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin (EC), on basal and stimulated testosterone production by rat Leydig cells in vitro. Leydig cells purified in a Percoll gradient were incubated for 3 h with GTE, EGCG or EC and the testosterone precursor androstenedione, in the presence or absence of either protein kinase A (PKA) or protein kinase C (PKC) activators. The reversibility of the effect was studied by pretreating cells for 15 min with GTE or EGCG, allowing them to recover for 1 h and challenging them for 2 h with human chorionic gonadotropin (hCG), luteinizing hormone releasing hormone (LHRH), 22(R)-hydroxycholesterol or androstenedione. GTE and EGCG, but not EC, inhibited both basal and kinase-stimulated testosterone production. Under the pretreatment conditions, the inhibitory effect of the higher concentration of GTE/EGCG on hCG/LHRH-stimulated or 22(R)-hydroxycholesterol-induced testosterone production was maintained, whereas androstenedione-supported testosterone production returned to control levels. At the lower concentration of GTE/EGCG, the inhibitory effect of these polyphenols on 22(R)-hydroxycholesterol-supported testosterone production was reversed. The inhibitory effects of GTE may be explained by the action of its principal component, EGCG, and the presence of a gallate group in its structure seems important for its high efficacy in inhibiting testosterone production. The mechanisms underlying the effects of GTE and EGCG involve the inhibition of the PKA/PKC signalling pathways, as well as the inhibition of P450 side-chain cleavage enzyme and 17beta-hydroxysteroid dehydrogenase function.

The relation of alpha-linolenic acid to the risk of prostate cancer: a systematic review and meta-analysis

BACKGROUND

alpha-Linolenic acid (ALA; 18:3n-3) has been associated inconsistently with an increased risk of prostate cancer. Additional studies have become available since the publication of 2 previous meta-analyses.

OBJECTIVE

The objective was to review the published data on the relation between ALA and prostate cancer.

DESIGN

We conducted a systematic review to identify studies that included data on ALA and risk of prostate cancer. Data were pooled from studies that compared the highest ALA quantile with the lowest ALA quantile, and risk estimates were combined by using a random-effects model.

RESULTS

The relation between ALA and prostate cancer is inconsistent across studies. We pooled data from 8 case-control and 8 prospective studies. The summary estimate revealed that high ALA dietary intakes or tissue concentrations are weakly associated with prostate cancer risk (relative risk [RR]: 1.20; 95% CI: 1.01, 1.43). When examined by study type (ie, retrospective compared with prospective or dietary ALA compared with tissue concentration) or by decade of publication, only the 6 studies examining blood or tissue ALA concentrations revealed a statistically significant association. With the exception of these studies, there was significant heterogeneity and evidence of publication bias. After adjustment for publication bias, there was no association between ALA and prostate cancer (RR: 0.96; 95% CI: 0.79, 1.17).

CONCLUSIONS

Studies examining the relation between ALA and prostate cancer have produced inconsistent findings. High ALA intakes or high blood and adipose tissue concentrations of ALA may be associated with a small increased risk of prostate cancer. However, these conclusions are qualified because of the heterogeneity across studies and the likelihood of publication bias.

Coexpression of the mutated BRCA1 mRNA and p53 mRNA and its association in Chinese prostate cancer

The mutations of BRCA1 and p53 genes have been simultaneously characterized in many tumors. However, their coexpression and associations have not been investigated quantitatively in prostate cancer. In the present study, the expressions of the mutated BRCA1 mRNA and p53 mRNA were examined in 48 Chinese prostate cancer cases and 10 corresponding adjacent benign tissues with in situ hybridization. The 5-year survival rates of the corresponding patients after operation were investigated. The results showed that the positive expressions of the mutated BCRA1 mRNA and p53 mRNA are involved in prostate cancer (P < 0.05). Moreover, there is a closed negative association between the expressions of the mutated BRCA1 gene and p53 gene in the mRNA level with the progression, angiogenesis, metastasis, and survival rate of prostate cancer. Their coexpression and negative association suggest that the two altered tumor suppressor genes might interact functionally in prostate cancer to provide a potential signal determining a prognosis of the tumor metastasis and survival rate. Further work will be done to elucidate the interaction mechanisms in prostate cancer.

2,2-bis(4-chlorophenyl)-1,1-dichloroethylene stimulates androgen independence in prostate cancer cells through combinatorial activation of mutant androgen receptor and mitogen-activated protein kinase pathways

Therapy resistance represents a major clinical challenge in disseminated prostate cancer for which only palliative treatment is available. One phenotype of therapy-resistant tumors is the expression of somatic, gain-of-function mutations of the androgen receptor (AR). Such mutant receptors can use noncanonical endogenous ligands (e.g., estrogen) as agonists, thereby promoting recurrent tumor formation. Additionally, selected AR mutants are sensitized to the estrogenic endocrine-disrupting compound (EDC) bisphenol A, present in the environment. Herein, screening of additional EDCs revealed that multiple tumor-derived AR mutants (including T877A, H874Y, L701H, and V715M) are sensitized to activation by the pesticide 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (DDE), thus indicating that this agent may impinge on AR signaling in cancer cells. Further investigation showed that DDE induced mutant AR recruitment to the prostate-specific antigen regulatory region, concomitant with an enhancement of target gene expression, and androgen-independent proliferation. By contrast, neither AR activation nor altered cellular proliferation was observed in cells expressing wild-type AR. Activation of signal transduction pathways was also observed based on rapid phosphorylation of mitogen-activated protein kinase (MAPK) and vasodilator-stimulated phosphoprotein, although only MAPK activation was associated with DDE-induced cellular proliferation. Functional analyses showed that both mutant AR and MAPK pathways contribute to the proliferative action of DDE, as evidenced through selective abrogation of each pathway. Together, these data show that exposure to environmentally relevant doses of EDCs can promote androgen-independent cellular proliferation in tumor cells expressing mutant AR and that DDE uses both mutant AR and MAPK pathways to exert its mitogenic activity.

Isoliquiritigenin inhibits migration and invasion of prostate cancer cells: possible mediation by decreased JNK/AP-1 signaling

Isoliquiritigenin (ISL, 4,2',4'-trihydroxychalcone), which is found in licorice, shallot and bean sprouts, is a potent antioxidant with anti-inflammatory and anti-carcinogenic effects. The purpose of this study was to investigate the effects of ISL treatment on the migration, invasion and adhesion characteristics of DU145 human prostate cancer cells. DU145 cells were cultured in the presence of 0-20 micromol/L ISL with or without 10 microg/L epidermal growth factor (EGF). ISL inhibited basal and EGF-induced cell migration, invasion and adhesion dose dependently. ISL decreased EGF-induced secretion of urokinase-type plasminogen activator (uPA), matrix metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and vascular endothelial growth factor (VEGF), but increased TIMP-2 secretion in a concentration-dependent manner. In addition, ISL decreased the protein levels of integrin-alpha2, intercellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM), and mRNA levels of uPA, MMP-9, VEGF, ICAM and integrin-alpha2. Furthermore, basal and EGF-induced activator protein (AP)-1 binding activity and phosphorylation of Jun N-terminal kinase (JNK), c-Jun and Akt were decreased after ISL treatment. However, phosphorylation of extracellular signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase was not altered. The JNK inhibitor SP600125 inhibited basal and EGF-induced secretion of uPA, VEGF, MMP-9 and TIMP-1, as well as AP-1 DNA binding activity and cell migration. These results provide evidence for the role of ISL as a potent antimetastatic agent, which can markedly inhibit the metastatic and invasive capacity of prostate cancer cells. The inhibition of JNK/AP-1 signaling may be one of the mechanisms by which ISL inhibits cancer cell invasion and migration.

Chemopreventive efficacy of inositol hexaphosphate against prostate tumor growth and progression in TRAMP mice

PURPOSE

Herein, for the first time, we evaluated the in vivo chemopreventive efficacy of inositol hexaphosphate (IP6), a major constituent of high-fiber diets, against prostate tumor growth and progression in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model.

EXPERIMENTAL DESIGN

Beginning at 4 weeks of age, male TRAMP mice were fed 2% (w/v) IP6 in drinking water or only drinking water till 24 weeks of age, and then sacrificed. Prostate tissue was subjected to histopathologic analysis and to immunohistochemical analyses for proliferation and apoptosis.

RESULTS

IP6 feeding did not show any adverse effect on fluid and diet consumption and body weight. There was a significant reduction (40%; P < 0.01) in lower urogenital tract weight in IP6-fed mice. IP6 inhibited prostate cancer progression at prostatic intraepithelial neoplasia stage and strongly reduced the incidence of adenocarcinoma (prostatic intraepithelial neoplasia/adenocarcinoma, 75:25% in the IP6 group versus 39:61% in the control group; P < 0.05). The incidences of well-differentiated and poorly differentiated adenocarcinomas in the IP6-fed group were reduced by 44% and 62%, respectively. Immunohistochemical analysis of prostate tissue showed a 26% decrease (P < 0.05) in proliferation cell nuclear antigen-positive cells and a 3.5-fold increase in apoptotic cells with no effect on Tag expression by IP6.

CONCLUSIONS

These findings are both novel and highly significant in establishing for the first time that oral IP6, without any toxicity, suppresses prostate tumor growth and progression at the neoplastic stage, thereby reducing the incidence of adenocarcinoma through its antiproliferative and proapoptotic effects, and thus indicating that IP6 could have potential chemopreventive effects against human prostate cancer.

Phenylboronic acid selectively inhibits human prostate and breast cancer cell migration and decreases viability

We compared the in vitro effect of boric acid (BA) versus phenylboronic acid (PBA) on the migration of prostate and breast cancer cell lines and non-tumorigenic cells from the same tissues. Treatment at 24 hours with BA (< or =500 microM) did not inhibit chemotaxis on fibronectin in any cell line. However, treatment over the same time course with concentrations of PBA as low as 1 muM significantly inhibited cancer cell migration without effecting non-tumorigenic cell lines. The compounds did not affect cell adhesion or viability at 24 hours but did alter morphology; both decreased cancer cell viability at eight days. These results suggest that PBA is more potent than BA in targeting the metastatic and proliferative properties of cancer cells.

Quality evaluation and prediction of Citrullus lanatus by 1H NMR-based metabolomics and multivariate analysis

(1)H NMR spectrometry in combination with multivariate analysis was considered to provide greater information on quality assessment over an ordinary sensory testing method due to its high reliability and high accuracy. The sensory quality evaluation of watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) was carried out by means of (1)H NMR-based metabolomics. Multivariate analyses by partial least-squares projections to latent structures-discrimination analysis (PLS-DA) and PLS-regression offered extensive information for quality differentiation and quality evaluation, respectively. The impact of watermelon and rootstock cultivars on the sensory qualities of watermelon was determined on the basis of (1)H NMR metabolic fingerprinting and profiling. The significant metabolites contributing to the discrimination were also identified. A multivariate calibration model was successfully constructed by PLS-regression with extremely high reliability and accuracy. Thus, (1)H NMR-based metabolomics with multivariate analysis was considered to be one of the most suitable complementary techniques that could be applied to assess and predict the sensory quality of watermelons and other horticultural plants.

Dietary n-3 polyunsaturated fatty acids enhance hormone ablation therapy in androgen-dependent prostate cancer

Hormone ablation therapy typically causes regression of prostate cancer and represents an important means of treating this disease, particularly after metastasis. However, hormone therapy inevitably loses its effectiveness as tumors become androgen-independent, and this conversion often leads to death because of subsequent poor responses to other forms of treatment. Because environmental factors, such as diet, have been strongly linked to prostate cancer, we examined the affects of dietary polyunsaturated fatty acids (PUFAs; at 1.5 wt%) on growth of androgen-dependent (CWR22) and androgen-independent (CWR22R) human prostatic cancer xenografts, the acute response of CWR22 tumors to ablation therapy, and their progression to androgen independence. Significant diet-induced changes in tumor n-3 or n-6 PUFA content had no affect on CWR22 or CWR22R tumors growing with or without androgen support, respectively. However, dietary changes that increased tumor eicosapentaenoic acid and linoleic acid content enhanced responses to ablation therapy, measured by cancer cell apoptosis and mitosis. In addition, relapse to androgen-independent growth (measured by renewed increases in tumor volume and serum prostate-specific antigen after ablation) positively correlated with tumor arachidonic acid content. There was no correlation between expression of 15-lipoxygenase isozymes or their products and tumor growth or responses to ablation. In conclusion, dietary n-3 PUFA may enhance the response of prostate cancer to ablation therapy and retard progression to androgen-independent growth by altering tumor PUFA content.

Lack of effect of walnuts on serum levels of prostate specific antigen: a brief report

OBJECTIVE

To examine whether the short-term consumption of walnuts, a food rich in alpha-linolenic acid, affects levels of serum prostate-specific antigen (PSA), a marker of prostate enlargement, inflammation, and cancer.

METHODS

Using data from a 12-month randomized crossover study examining the effect of walnut consumption on body composition, we examined whether increased walnut consumption (mean 35 grams daily, 12% total energy) affected serum PSA levels among 40 middle-aged men.

RESULTS

There was no significant difference between mean PSA level at the conclusion of the 6-month walnut-supplemented diet (1.05 mug/L, 95% CI [0.81, 1.37]) and the conclusion of the 6-month control diet (1.06 mug/L, 95% CI [0.81, 1.38]) (P = 0.86) (or a mean proportional decrease in PSA of -1%).

CONCLUSIONS

Our results suggest that short-term consumption of walnuts is unlikely to affect PSA levels adversely among otherwise normal men.

Fat and meat intake and prostate cancer risk: the multiethnic cohort study

Dietary fat and meat as potential risk factors for prostate cancer have been the focus of many epidemiologic investigations, and findings from recent studies in particular have been inconsistent. Therefore, we examined the association between these exposures and prostate cancer risk in the Multiethnic Cohort Study. The analyses included 82,483 men in Hawaii and Los Angeles aged >or=45, who completed a detailed quantitative food frequency questionnaire in 1993-1996. During the follow-up period of 8 years, a total of 4,404 incident cases, including 1,278 nonlocalized or high-grade cancer cases, were identified. Cox proportional hazard models were used to estimate relative risks of prostate cancer after adjustment for time on study, ethnicity, family history of prostate cancer, education, body mass index, smoking status and energy intake. Intake of different types of fat (total, saturated, monounsaturated or polyunsaturated), n-6 fatty acid, cholesterol, various meats, and fats from meat showed no association with overall prostate cancer risk or with nonlocalized or high-grade prostate cancer. Furthermore, we found little evidence of any relation of fat and meat intake with prostate cancer risk within any of the 4 racial/ethnic groups (African Americans, Japanese Americans, Latinos and Whites). There was a suggestion of a protective effect of n-3 fatty acid intake that was limited to Latinos and Whites. However, overall, our findings from a large cohort study of ethnically diverse population give no indication that intake of fat and meat substantially affects prostate cancer risk.

Androgen-dependent regulation of medium and long chain fatty acids uptake in prostate cancer

BACKGROUND

Epidemiological and experimental studies suggest that both fatty acids and androgens have a role in the development and progression of prostate cancer (PC). Plasma membrane fatty acid binding protein (FABP(pm)) is a transporter of medium and long chain fatty acids (MCFA and LCFA) across the plasma membrane, and is identical to the mitochondrial protein aspartate aminotransferase (mAAT) that is regulated by testosterone only in prostate epithelial cells, a site where PC initially develops. We therefore hypothesized that FABP(pm) is also regulated by androgens.

METHODS

We examined the effect of a synthetic androgen, R1881, and that of androgen receptor (AR) blocker, bicalutamide, on the expression of FABP(pm) and mAAT and on the uptake of fatty acids in the androgen-sensitive LNCaP, androgen responsive 22rv1 and androgen-independent CL1 human PC cells. This was done using immunofluorescence and confocal microscopy, Western blot, flow cytometry, and (3)H-oleate uptake studies.

RESULTS

Androgen supplementation increased the cellular and surface expression of FABP(pm) and mAAT and increased the uptake of fluorescently labeled MCFA and LCFA and that of (3)H-oleate only in PC cells that express the AR. Bicalutamide inhibited this phenomenon.

CONCLUSIONS

The uptake of MCFA and LCFA into PC cells is androgen regulated as well as the expression of FABP(pm) and mAAT.

The use of herbal and over-the-counter dietary supplements for the prevention of prostate cancer

Having a high probability of experiencing prostate cancer during their lifetime, men are increasingly seeking protection against this disease with the use of over-the-counter dietary supplements containing herbs, vitamins, or plant-derived biochemical agents. The use of these agents for prostate cancer prevention is driven by epidemiology supporting the idea that regional diets and consumption of specific dietary components (certain herbs, vitamins, isoflavones, and polyphenols) are associated with a lower risk for prostate cancer, in conjunction with basic research that is defining molecules within food substances that kill or suppress growth of cultured human prostate cancer cells. Moreover, there is a sense that these dietary agents lack side effects, although this assumption often is faulty. Unfortunately, at this time, there is insufficient clinical evidence to support the widespread use of these dietary supplements for chemoprevention of prostate cancer, although ongoing clinical trials of the most promising vitamins and minerals are approaching conclusion.

A prospective study of dietary calcium, dairy products and prostate cancer risk (Finland)

High dietary intakes of calcium and dairy products have been hypothesized to enhance prostate cancer risk, but available prospective data regarding these associations are inconsistent. We examined dietary intakes of calcium and dairy products in relation to risk of prostate cancer in the Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study, a cohort of 29,133 male smokers aged 50-69 years at study entry. Dietary intake was assessed at baseline using a validated 276-item food use questionnaire. Cox proportional hazards regression was used to adjust for known or suspected risk factors for prostate cancer. During 17 years of follow-up, we ascertained 1,267 incident cases of prostate cancer. High versus low intake of dietary calcium was associated with a marked increase in prostate cancer risk. The multivariate relative risk (RR) of prostate cancer for > or =2,000 mg/day compared to <1,000 mg/day of calcium intake was 1.63 (95% confidence interval (CI), 1.27-2.10; p trend < 0.0001). Total dairy intake was also positively associated with risk of prostate cancer. The multivariate RR of prostate cancer comparing extreme quintiles of intake was 1.26 (95% CI, 1.04-1.51; p trend = 0.03). However, no association with total dairy intake remained after we adjusted for calcium (p trend = 0.17). Findings were similar by stage and grade of prostate cancer. The results from this large prospective study suggest that intake of calcium or some related component contained in dairy foods is associated with increased prostate cancer risk.

A prospective investigation of height and prostate cancer risk

Greater adult height, which reflects a combination of early nutrition, exposure to androgens, growth hormones, and other factors during growth and development, as well as heredity, has been associated with increased prostate cancer risk in several observational studies, but findings have been inconsistent. We examined this relationship in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort. At baseline, 29,119 Finnish male smokers 50 to 69 years old had height and weight measured by trained personnel, provided information on demographic, smoking, medical, and other characteristics, and completed an extensive diet history questionnaire. A total of 1,346 incident prostate cancer cases were identified during a follow-up period of up to 17.4 years (median, 14.1 years). In age-adjusted Cox proportional hazards models, the hazard ratios and 95% confidence intervals for prostate cancer according to increasing quintiles of height [<or=168, 169-171, 172-175, 176-178, and >178 cm] were 1.00 (reference), 1.11 (0.93-1.32), 1.11 (0.95-1.31), 1.30 (1.01-1.55), and 1.14 (0.96-1.35); P(trend) = 0.04. In analyses stratified by disease stage (available for 916 cases), a strong dose-response relationship was observed between greater height and advanced, but not earlier-stage, disease [tumor-node-metastasis stage III-IV, hazard ratio and 95% confidence interval for increasing quintiles of height: 1.77 (1.18-2.65), 1.82 (1.25-2.65), 1.93 (1.29-2.90), and 2.02 (1.37-2.97); P(trend) = 0.0008, P(interaction) = 0.002]. Our study provides additional evidence that increased height is a risk factor for prostate cancer and suggests that taller men are particularly susceptible to advanced disease.

Impact of nutrients on insulin-like growth factor-I, insulin-like growth factor binding protein-3 and their ratio in African American and white males

OBJECTIVE

Higher levels of insulin-like growth factor-I (IGF-I) and lower levels of IGF binding protein-3 (IGFBP-3) have been associated with an increased risk of prostate cancer. Nutrition is known to partially regulate IGF levels and it is possible that nutritional factors mediate the impact of IGF levels on prostate cancer risk.

DESIGN

A cross-sectional analysis of the impact of nutritional factors measured by a dietary questionnaire on plasma levels of IGF-I, IGFBP-3 and their molar ratio. Multiple linear regression analysis was used to test for effects of nutrients on IGF levels.

SETTING

Prostate cancer screening at the Hollings Cancer Center in Charleston, South Carolina.

SUBJECTS

Ninety-five African American and 138 white males aged 33-83 years attending the screening.

RESULTS

In whites, intakes of total, saturated and monounsaturated fats were positively associated with an increase in the molar ratio, while there was no association in African Americans. In African Americans, we found that increasing intake of calcium and dairy servings was positively associated with IGF-I levels. Increased vegetable intake was positively associated with IGFBP-3 in African Americans, while there was no effect in whites. A higher percentage of alcohol in the total diet was significantly associated with a decrease in the molar ratio and an increase in IGFBP-3 in both groups.

CONCLUSIONS

Our results confirm previous findings of nutritional determinants of IGF levels. Additionally, we found the impact of several nutrients on IGF levels to be different in whites and African Americans, which warrants further investigation.

Prostate cancer incidence and intake of fruits, vegetables and related micronutrients: the multiethnic cohort study* (United States)

OBJECTIVE

To describe the relationship between the intake of fruits, vegetables, and related vitamins and antioxidants, and the risk of prostate cancer in male participants in a large multiethnic cohort study.

METHODS

Food and nutrient intakes in 1993-1996 were calculated from a detailed food frequency questionnaire (FFQ) designed to account for the food and nutrient intake of the ethnic groups represented in the study (82,486 African-American, Japanese-American, Native-Hawaiian, Latino and White males included here). Follow-up for incident cancers utilized local SEER registries. Vital status was ascertained using state death files. Data on PSA utilization from a later questionnaire was also examined.

RESULTS

A total of 3,922 incident cancer cases were ascertained during follow-up. Modestly increased risks of prostate cancer were observed in relation to higher intakes of several food items including light green lettuce and dark leafy green vegetables. Notably, no significant protective associations of any foods were seen, including tomato intake; and intakes of two complex foods containing tomato sauce (pizza and Spanish rice) were associated with modest increases in risk. PSA test use was significantly and positively related to intake of some of these same items, implying a degree of disease detection-bias. Analysis of non-localized and high grade disease (1,345 cases) showed no significant protective associations with overall fruits and vegetables intake, related micronutrients, or with intake of selected complex food items.

CONCLUSIONS

We found no statistically significant evidence of a protective effect against prostate cancer of higher levels of intake of any of these foods, associated micronutrients or supplements. A possible explanation for the positive associations with risk of several of the foods normally considered to be healthy is detection bias, since "healthy" dietary intake was related to greater use of the PSA test.