Inflammation in the etiology of prostate cancer: an epidemiologic perspective

Dietary caloric input and tumor growth accelerate senescence and modulate liver and adipose tissue crosstalk

Metabolic alterations are related to tumorigenesis and other age-related diseases that are accelerated by "Westernized" diets. In fact, hypercaloric nutrition is associated with an increased incidence of cancers and faster aging. Conversely, lifespan-extending strategies, such as caloric restriction, impose beneficial effects on both processes. Here, we investigated the metabolic consequences of hypercaloric-induced aging on tumor growth in female mice. Our findings indicate that a high-fat high-sucrose diet increases tumor growth mainly due to the boosted oxidation of glucose and fatty acids. Consequently, through an increased expression of lactate, IGFBP3, and PTHLH, tumors modulate liver and white adipose tissue metabolism. In the liver, the induced tumor increases fibrosis and accelerates the senescence process, despite the lower systemic pro-inflammatory state. Importantly, the induced tumor induces the wasting and browning of white adipose tissue, thereby reversing diet-induced insulin resistance. Finally, we suggest that tumor growth alters liver-adipose tissue crosstalk that upregulates Fgf21, induces senescence, and negatively modulates lipids and carbohydrates metabolism even in caloric-restricted-fed mice.

Unraveling the link between cardiorespiratory fitness and cancer: a state-of-the-art review

Cardiorespiratory fitness (CRF) not only reflects an individual's capacity to perform physical activities but also encapsulates broader effects on the basic biology of aging. This review aims to summarize the evidence on the influence of CRF on overall and site-specific cancer risks. It delves into the biological mechanisms through which CRF may exert its effects, explores the clinical implications of these findings, identifies gaps in the current evidence base, and suggests directions for future research. The synthesis of findings reveals that higher CRF levels (general threshold of > 7 METs) are consistently associated with a reduced risk of a range of cancers, including head and neck, lung, breast, gastrointestinal, particularly pancreatic and colorectal, bladder, overall cancer incidence and mortality, and potentially stomach and liver, bile duct, and gall bladder cancers. These inverse associations between CRF and cancer risk do not generally differ across age groups, sex, race, or adiposity, suggesting a universal protective effect of CRF. Nonetheless, evidence linking CRF with skin, mouth and pharynx, kidney, and endometrial cancers is limited and inconclusive. Conversely, higher CRF levels may be potentially linked to an increased risk of prostate cancer and hematological malignancies, such as leukemia and myeloma, although the evidence is still not conclusive. CRF appears to play a significant role in reducing the risk of several cancers through various biological mechanisms, including inflammation reduction, immune system enhancement, hormonal regulation, and metabolic improvements. Overall, enhancing CRF through regular physical activity offers a vital, accessible strategy for reducing cancer risk and extending the health span. Future research should aim to fill the existing evidence gaps regarding specific cancers and elucidate the detailed dose-response relationships between CRF levels and cancer risk. Studies are also needed to elucidate the causal relationships and mechanistic pathways linking CRF to cancer outcomes.

Spatial distribution of tumor-associated macrophages in an orthotopic prostate cancer mouse model

Mounting evidence suggests that the immune landscape within prostate tumors influences progression, metastasis, treatment response, and patient outcomes. In this study, we investigated the spatial density of innate immune cell populations within NOD.SCID orthotopic prostate cancer xenografts following microinjection of human DU145 prostate cancer cells. Our laboratory has previously developed nanoscale liposomes that attach to leukocytes via conjugated E-selectin (ES) and kill cancer cells via TNF-related apoptosis inducing ligand (TRAIL). Immunohistochemistry (IHC) staining was performed on tumor samples to identify and quantify leukocyte infiltration for different periods of tumor growth and E-selectin/TRAIL (EST) liposome treatments. We examined the spatial-temporal dynamics of three different immune cell types infiltrating tumors using QuPath image analysis software. IHC staining revealed that F4/80+ tumor-associated macrophages (TAMs) were the most abundant immune cells in all groups, irrespective of time or treatment. The density of TAMs decreased over the course of tumor growth and decreased in response to EST liposome treatments. Intratumoral versus marginal analysis showed a greater presence of TAMs in the marginal regions at 3 weeks of tumor growth which became more evenly distributed over time and in tumors treated with EST liposomes. TUNEL staining indicated that EST liposomes significantly increased cell apoptosis in treated tumors. Additionally, confocal microscopy identified liposome-coated TAMs in both the core and periphery of tumors, highlighting the ability of liposomes to infiltrate tumors by "piggybacking" on macrophages. The results of this study indicate that TAMs represent the majority of innate immune cells within NOD.SCID orthotopic prostate tumors, and spatial density varies widely as a function of tumor size, duration of tumor growth, and treatment of EST liposomes.

Association of Cytokine Gene Polymorphisms with Prostate Cancer Risk from a Study in Central China

Our study intended to investigate five cytokine gene single nucleotide polymorphisms (SNPs) and their associations with prostate cancer risk. Genotypes of five cytokine gene SNPs were detected by MassARRAY for blood samples from a group of patients with prostate cancer (n = 90) and a control group (n = 140) in central China. The differences in tumor clinical stages, Gleason scores, and PSA values in patients with prostate cancer were also investigated. The frequencies of the five cytokine gene SNPs (L-1β rs16944, IL-4 rs2070874, IL-4rs2227284, IL-16 rs7175701, and IL-16 rs11556218) genotypes were not found to be significantly mutated in prostate cancer patients compared with the control group. In addition, for five cytokine gene SNPs genotypic comparisons, patients with different Gleason scores, clinical stages, and PSA values were grouped into two subgroups. There was also no statistically significant association in all these subgroups. Our study suggests that cytokine gene polymorphisms may not be a risk factor for prostate cancer in a central Chinese population. Nevertheless, more large-scale studies on the Chinese population are necessary to examine our conclusions. The discovery of cytokine gene polymorphisms related to prostate cancer could update our understanding of the etiology and improve our knowledge of the early detection, diagnosis, and treatment of prostate cancer.

Cardiorespiratory fitness is not associated with reduced risk of prostate cancer: A cohort study and review of the literature

BACKGROUND

Cardiorespiratory fitness (CRF) has a strong inverse relationship with several chronic disease outcomes, including some cancers. The association between CRF and prostate cancer is controversial. We aimed to assess the prospective association of CRF with prostate cancer risk using a cohort study and review of the literature.

MATERIAL AND METHODS

Cardiorespiratory fitness was assessed using a respiratory gas exchange analyser during exercise testing in 2204 cancer-free middle-aged men. Hazard ratios (HRs) with 95% confidence interval (CIs) were estimated. We corrected for within-person variability in CRF levels using repeat measurements.

RESULTS

During a median follow-up of 24.9 years, 216 prostate cancer cases occurred. The age-adjusted regression dilution ratio of CRF was 0.58 (95% CI: 0.53-0.64). The HR (95% CI) of prostate cancer per 1 standard deviation increase in CRF in age-adjusted analysis was 1.10 (0.95-1.27). The association remained consistent after further adjustment for several risk factors (HR 1.13; 95% CI 0.96-1.33). The corresponding adjusted HRs were 1.24 (95% CI: 0.87-1.77) and 1.28 (95% CI: 0.87-1.88), respectively, when comparing the extreme tertiles of CRF levels. Previous studies mostly reported no evidence of an association or an increased risk of prostate cancer in relation to high CRF. Studies reporting positive associations had short-term follow-up durations (<10 years).

CONCLUSIONS

Primary data and a review of previous studies suggest that elevated CRF is not associated with reduced prostate cancer risk. Previous findings of significant evidence of associations could be attributed to increased screening and detection as well as reverse causation bias.

Validation of the Effectiveness of Neutrophil-to-lymphocyte Ratio (NLR) as a Predictive Factor in Patients Undergoing Prostate Biopsy With Prostate Specific Antigen (PSA) Between 4.0 and 10.0 ng/ml

BACKGROUND/AIM

This study aimed to access the effectiveness of serum neutrophil-to-lymphocyte ratio (NLR) in patients undergoing prostate needle biopsy with a prostate specific antigen (PSA) between 4.0 and 10.0 ng/ml.

PATIENTS AND METHODS

A total of 633 cases were eligible. We evaluated several factors including age, PSA, PSA-density (PSAD), platelet-to-lymphocyte ratio (PLR) and NLR in the presence or absence of prostate cancer (PCa), retrospectively. We evaluated statistically the associations between each factor and pathological findings or Gleason score.

RESULTS

A total of 201 were evaluated in this study. Regarding the presence or absence of prostate cancer, there were statistically significant differences in age, PSA levels, PSAD, the PLR and NLR. The mean NLR value of the patients with PCa was significantly lower compared to the entire cohort. Multivariate analysis showed that age, PSAD, and NLR were independent risk factors predicting PCa.

CONCLUSION

For patients having a PSA between 4.0 and 10.0 ng/ml, NLR was a predicting factor of PCa prior to prostate needle biopsy and an effective biomarker and useful tool for avoiding unnecessary biopsies.

Prostate immunology: A challenging puzzle

Mucosal immunity defines the relationship of surfaces in contact with the environment and integrates diverse tissues such as epidermis, gum, nose, gut, uterus and prostate with the immune system. Although considered part of a system, each mucosa presents specific immune features beyond the barrier and secretory functions. Information regarding the mucosal immunology of the male reproductive tract and the prostate gland in particular is scarce. In this review, we approach the prostate as an epithelial barrier and as part of the mucosal immune system. Finally, we also raise a series of questions that will improve the understanding of this gland, its role in reproduction and its sensitivity/resistance to disease.

Predictive Value of Neutrophil to Lymphocyte Ratio in the Diagnosis of Significant Prostate Cancer at Initial Biopsy: A Comparison with Free Percent Prostate Specific Antigen, Prostate Specific Antigen Density and Primary Circulating Prostate Cells

Introduction:

An elevated serum PSA is the only biomarker routinely used in screening for prostate cancer to indicate a prostate biopsy. However, it is not specific for prostate cancer and the neutrophil/lymphocyte ratio has been suggested as an alternative. We present a prospective study of men with an elevated PSA and compare the neutrophil/lymphocyte ratio, free percent PSA, PSA density and the presence of circulating prostate cells to detect clinically significant prostate cancer at first biopsy.

Patients and Methods:

Prospective study of consecutive men with a PSA 4-10 ng/ml referred for initial prostate biopsy, the results were compared with the neutrophil/lymphocyte ratio, free percent PSA and PSA density. Circulating prostate cells (CPCs) were detected using immunocytochemistry. The blood sample was taken immediately before the prostate biopsy.

Results:

1,223 men participated, 38% (467) of whom had prostate cancer detected, of these 322 were clinically significant. The area under the curves were for neutrophil/lymphocyte ratio, free percent PSA, PSA density and CPC detection were 0.570, 0.785, 0,620 and 0.844 respectively. Sensitivity/specificity were 0.388/0.685, 0.419/0.897, 0.598/0.624 and 0.966/0.786 respectively. The neutrophil/lymphocyte ratio did not differentiate between benign and malignant disease.

Conclusions:

The neutrophil/lymphocyte ratio did not discriminate between benign and malignant prostatic disease in patients with a PSA between 4-10ng/ml.

Circulating inflammation markers and prostate cancer

BACKGROUND

Chronic inflammation is thought to influence the risk of prostate cancer. The purpose of this population-based case-control study was to evaluate the association of 48 circulating inflammation markers with prostate cancer, to identify candidate markers for further investigation.

METHODS

Serum samples collected from 235 prostate cancer patients and 198 population-based controls recruited in Örebro County, Sweden, in 1989-1991, were assessed using a multiplex bead-based immunoassay to determine concentrations of 48 circulating inflammation markers. Logistic regression was first used to evaluate the association between individual markers (highest vs lowest concentration quartile) and prostate cancer in unadjusted and mutually adjusted models. Second, patients with inflammatory conditions, metastatic or advanced prostate cancer, were excluded to address the possible influence of systemic disease on inflammation markers.

RESULTS

Individual analyses first identified 21 markers associated with prostate cancer (P < .05), which after mutual adjustment were reduced to seven markers. After the exclusion of men with conditions linked with systemic inflammation, associations between prostate cancer and deviant levels of C-X3-C motif chemokine ligand 1, platelet-derived growth factor subunit B homodimer, interleukin 10, C-C motif chemokine ligand (CCL) 21, and CCL11 remained statistically significant.

CONCLUSIONS

In this explorative study, we identified candidate inflammation markers of possible importance for prostate cancer pathophysiology, for further evaluation in prospective studies.

Chronic inflammatory diseases, anti-inflammatory medications and risk of prostate cancer: a population-based case-control study

Background

Whether chronic inflammation increases prostate cancer risk remains unclear. This study investigated whether chronic inflammatory diseases (CID) or anti-inflammatory medication use (AIM) were associated with prostate cancer risk.

Methods

Fifty-five thousand nine hundred thirty-seven cases (all prostate cancer, 2007–2012) and 279,618 age-matched controls were selected from the Prostate Cancer Database Sweden. CIDs and AIMs was determined from national patient and drug registers. Associations were investigated using conditional logistic regression, including for disease/drug subtypes and exposure length/dose.

Results

Men with a history of any CID had slightly increased risk of any prostate cancer diagnosis (OR: 1.08; 95%CI: 1.04–1.12) but not ‘unfavourable’ (high-risk or advanced) prostate cancer. Generally, risk of prostate cancer was highest for shorter exposure times. However, a positive association was observed for asthma > 5 years before prostate cancer diagnosis (OR: 1.21; 95%CI: 1.05–1.40). Risk of prostate cancer was increased with prior use of any AIMs (OR: 1.26; 95%CI: 1.24–1.29). A positive trend with increasing cumulative dose was only observed for inhaled glucocorticoids (p < 0.011).

Conclusion

Detection bias most likely explains the elevated risk of prostate cancer with prior history of CIDs or use of AIMs, given the higher risk immediately after first CID event and lack of dose response. However, findings for length of time with asthma and dose of inhaled glucocorticoids suggest that asthma may increase risk of prostate cancer through other pathways.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5846-3) contains supplementary material, which is available to authorized users.

Molecular Mechanisms of Zinc as a Pro-Antioxidant Mediator: Clinical Therapeutic Implications

The essentiality of zinc as a trace mineral in human health has been recognized for over five decades. Zinc deficiency, caused by diet, genetic defects, or diseases, can cause growth retardation, delayed sexual maturation, depressed immune response, and abnormal cognitive functions in humans. Zinc supplementation in zinc-deficient individuals can overcome or attenuate these abnormalities, suggesting zinc is an essential micro-nutrient in the body. A large number of in vitro and in vivo experimental studies indicate that zinc deficiency also causes apoptosis, cellular dysfunction, deoxyribonucleic acid (DNA) damage, and depressed immune response. Oxidative stress, due to the imbalance of reactive oxygen species (ROS) production and detoxification in the anti-oxidant defense system of the body, along with subsequent chronic inflammation, is believed to be associated with many chronic degenerative diseases such as diabetes, heart diseases, cancers, alcohol-related disease, macular degenerative disease, and neuro-pathogenesis. A large number of experimental studies including cell culture, animal, and human clinical studies have provided supportive evidence showing that zinc acts as an anti-oxidative stress agent by inhibition of oxidation of macro-molecules such as (DNA)/ribonucleic acid (RNA) and proteins as well as inhibition of inflammatory response, eventually resulting in the down-regulation of (ROS) production and the improvement of human health. In this article, we will discuss the molecular mechanisms of zinc as an anti-oxidative stress agent or mediator in the body. We will also discuss the applications of zinc supplementation as an anti-oxidative stress agent or mediator in human health and disease.

The influence of prostatic Cutibacterium acnes infection on serum levels of IL6 and CXCL8 in prostate cancer patients

Background

Chronic prostatic inflammation, caused by Cutibacterium acnes (C. acnes), has been proposed to influence the risk of prostate cancer development. In vitro studies have demonstrated the capacity of C. acnes to induce secretion of Interleukin 6 (IL6) and C-X-C motif chemokine ligand 8 (CXCL8) by prostate epithelial cells. Both these inflammatory mediators have been implicated in prostate cancer pathophysiology. In this cohort study, we aimed to investigate the influence of prostatic C. acnes on serum levels of IL6 and CXCL8.

Methods

We recruited 99 prostate cancer patients who underwent radical prostatectomy at Örebro University Hospital. The cultivation of pre-operatively obtained prostate biopsies identified C. acnes in 60 of the 99 patients. Levels of IL6 and CXCL8 in pre-operative serum samples were analyzed using ELISA, and concentrations were compared between prostate cancer patients with and without prostatic C. acnes infection using standard statistical methods.

Results

No statistical differences were observed in serum levels of IL6 and CXCL8 between subjects with and without prostatic C. acnes infection.

Conclusions

Our results indicate that prostatic C. acnes infection may give rise to low-grade inflammation with little effect on systemic levels of IL6 and CXCL8.

Adipocyte p62/SQSTM1 Suppresses Tumorigenesis through Opposite Regulations of Metabolism in Adipose Tissue and Tumor

Obesity is a leading risk factor for cancer. However, understanding the crosstalk between adipocytes and tumor cells in vivo, independently of dietary contributions, is a major gap in the field. Here we used a prostate cancer (PCa) mouse model in which the signaling adaptor p62/Sqstm1 is selectively inactivated in adipocytes. p62 loss in adipocytes results in increased osteopontin secretion, which mediates tumor fatty acid oxidation and invasion, leading to aggressive metastatic PCa in vivo. Furthermore, p62 deficiency triggers in adipocytes a general shutdown of energy-utilizing pathways through mTORC1 inhibition, which supports nutrient availability for cancer cells. This reveals a central role of adipocyte's p62 in the symbiotic adipose tissue-tumor collaboration that enables cancer metabolic fitness.

Appendicitis before Age 20 Years Is Associated with an Increased Risk of Later Prostate Cancer

Background: Appendicitis before age 20 years has been observed to influence the risk of several inflammatory conditions, possibly through underlying immunological mechanisms. Inflammation has further been suggested to be involved in prostate cancer development. We therefore hypothesized that immunological characteristics signaled by appendicitis before late adolescence might influence the risk of later prostate cancer, and aimed to evaluate this association in a population-based study.Methods: We identified a large cohort of Swedish men who underwent assessment for military conscription around the age of 18 years (n = 242,573). Medical diagnoses at time of conscription were available through the Swedish Military Conscription Register. The Swedish Cancer Register was used to identify diagnoses of prostate cancer. Multivariable adjusted Cox regression analyses were used to estimate HR and 95% confidence intervals (95% CIs) for the association between appendicitis and prostate cancer.Results: During a median of 36.7 years of follow-up, 1,684 diagnoses of prostate cancer occurred. We found a statistically significant association between appendicitis and overall prostate cancer (adjusted HR 1.70; 95% CI, 1.08-2.67). The risk was notably increased for advanced (HR 4.42; 95% CI, 1.74-11.22) and lethal (HR 8.95; 95% CI, 2.98-26.91) prostate cancer.Conclusions: These results suggest that a diagnosis of appendicitis before adulthood potentially signals underlying immune characteristics and a pattern of inflammatory response relevant to prostate cancer risk.Impact: The study lends support to the proposed role of inflammation in prostate carcinogenesis, and adds another area of investigation potentially relevant to prostate cancer development. Cancer Epidemiol Biomarkers Prev; 27(6); 660-4. ©2018 AACR.

Association of the neutrophil-to-lymphocyte ratio and prostate cancer detection rates in patients via contemporary multi-core prostate biopsy

The aim of this study was to determine whether the neutrophil-to-lymphocyte ratio (NLR), a measure of the systemic inflammatory response is associated with the overall prostate cancer detection rate in men who underwent contemporary multi (≥12)-core transrectal ultrasound (TRUS) biopsy. We reviewed the records of 3913 patients with initial prostate-specific antigen (PSA) levels ranging from 4 to 10 ng ml⁻¹ who underwent TRUS-guided prostate biopsy between April 2006 and May 2014. NLR was calculated by prebiopsy neutrophil and lymphocyte counts. We excluded patients who had evidence of acute prostatitis, a history of prostate surgery, and any systemic inflammatory disease. A multivariate logistic regression model was used to analyze prostate cancer detection. After adjusting for confounding factors, predictive values were determined according to the receiver operating characteristic-derived area under the curve, both including and excluding the NLR variable. In univariate analyses, NLR was a significant predictor of prostate cancer detection (P < 0.001). In multivariate analyses, a higher NLR was significantly associated with prostate cancer detection after adjusting for other factors (OR = 1.372, P = 0.038). The addition of NLR increased the accuracy from 0.712 to 0.725 (P = 0.005) in the multivariate model for prostate cancer detection. NLR may be a potentially useful clinical marker in the detection of prostate cancer among men with a PSA level in the 4–10 ng ml⁻¹ range. These findings are derived from a retrospective analysis and should be validated in larger populations through prospective studies.

Gamma-glutamyltransferase and risk of prostate cancer: Findings from the KIHD prospective cohort study

Increased circulating serum gamma-glutamyltransferase (GGT) has been linked with an increased risk of chronic disease outcomes, including overall and several site-specific cancers. However, the relationship of GGT with prostate cancer risk is uncertain. We aimed to assess the prospective association of GGT with risk of prostate cancer. Serum GGT activity was assessed at baseline in the Finnish Kuopio Ischemic Heart Disease prospective cohort of 2,390 men aged 42-61 years without a history of cancer at baseline. We corrected for within-person variability in GGT values using data from repeat measurements taken several years apart. During a median follow-up of 24.6 years, 230 cases of prostate cancer occurred. The age-adjusted regression dilution ratio for log_e GGT was 0.69 [95% confidence interval (CI): 0.63-0.74]. Serum GGT was nonlinearly associated with risk of prostate cancer. In age-adjusted Cox regression analysis, the hazard ratio (95% CIs) for prostate cancer in a comparison of the top quartile versus bottom quartiles 1-3 of GGT values was 1.43 (1.07 to 1.93; p = 0.017), which persisted on adjustment for several established cancer risk factors 1.46 (1.06 to 2.02; p = 0.020). The association remained unchanged on further adjustment for total energy intake, socioeconomic status, physical activity and C-reactive protein. The association did not importantly vary across several clinical subgroups. GGT is positively and independently associated with future risk of prostate cancer in a middle-aged Finnish male population over long-term follow-up. Further research is needed to understand the mechanistic pathways involved and if GGT may have potential relevance in prostate cancer prevention.

Predictive value of neutrophil-to-lymphocyte ratio in diagnosis of prostate cancer among men who underwent template-guided prostate biopsy: A STROBE-compliant study

To evaluate the predictive value of neutrophil-to-lymphocyte ratio (NLR) in diagnosis of prostate cancer (PCa). Data of 662 patients who underwent prostate biopsy from January 2012 to June 2016 were retrospectively reviewed. The receiver operating characteristic-derived area under the curve analyses were performed to assess the predictive accuracy. Simultaneously, Youden's index was calculated to determine the optimal NLR cutoff. Furthermore, univariate and multivariate logistic regression analyses were performed to determine the association between NLR value and PCa detection. On account of an NLR value of 2.44 was shown with the maximal Youden's index on the receiver operating characteristic curve, the cutoff value of NLR was set at 2.44. Accordingly, patients were classified into high-NLR or low-NLR group. The patients in high-NLR group might have significant higher risk to be diagnosed with PCa (HR 1.640; P = 0.031), especially in the subgroup with prostate-specific antigen (PSA) ranged from 4 to 10 ng mL (hazard ratio [HR] 4.364; P = 0.003). The high-NLR was independent of age of diagnosis, PSA, prostate volume, abnormal digital rectal examination, and hypoechoic lesion on transrectal ultrasound for positive prostate biopsy. In the so-called gray area, combination of NLR value could raise 4.6% of the accuracy of the multivariate logistic model in PCa prediction, but not in advanced PCa prediction.The patients with high-NLR value may have significant higher risk to be diagnosed with PCa, especially among the patients with PSA ranged from 4 to 10 ng mL. In this subgroup, the adding of NLR value in the multivariate model can improve the accuracy of PCa prediction in a large degree. If validated, the NLR will become a promising, accessible, inexpensive biomarker for PCa prediction.

Prostate cancer outcomes for men who present with symptoms at diagnosis

OBJECTIVE

To compare clinical features, treatments and outcomes in men with non-metastatic prostate cancer (PCa) according to whether they were referred for symptoms or elevated prostate-specific antigen (PSA) level.

PATIENTS AND METHODS

This study used data from the South Australia Prostate Cancer Clinical Outcomes Collaborative database; a multi-institutional clinical registry covering both the public and private sectors. We included all non-metastatic cases from 1998 to 2013 referred for urinary/prostatic symptoms or elevated PSA level. Multivariate Poisson regression was used to identify characteristics associated with symptomatic presentation and compare treatments according to reason for referral. Outcomes (i.e. overall survival, PCa-specific survival, metastasis-free survival and disease-free survival) were compared using multivariate Cox proportional hazards and competing risk regression.

RESULTS

Our analytical cohort consisted of 4 841 men with localized PCa. Symptomatic men had lower-risk disease (incidence ratio [IR] 0.70, 95% confidence interval [CI] 0.61-0.81 for high vs low risk), fewer radical prostatectomies (IR 0.64, CI: 0.56-0.75) and less radiotherapy (IR 0.86, CI: 0.77-0.96) than men presenting with elevated PSA level. All-cause mortality (hazard ratio [HR] 1.31, CI: 1.16-1.47), disease-specific mortality (HR 1.42, CI: 1.13-1.77) and risk of metastases (HR 1.36, CI: 1.13-1.64) were higher for men presenting with symptoms, after adjustment for other clinical characteristics; however, risk of disease progression did not differ (HR 0.90, CI: 0.74-1.07) amongst those treated curatively. Subgroup analyses indicated poorer PCa survival for symptomatic referral among men undergoing radical prostatectomy (HR 3.4, CI: 1.3-8.8), those aged >70 years (HR 1.4, CI: 1.0-1.8), men receiving private treatment (HR 2.1, CI: 1.3-3.3), those diagnosed via biopsy (HR 1.3, CI: 1.0-1.7) and those diagnosed before 2006 (HR 1.6, CI: 1.2-2.7).

CONCLUSION

Our results suggest that symptomatic presentation may be an independent negative prognostic indicator for PCa survival. More complete assessment of disease grade and extent, more definitive treatment and increased post-treatment monitoring among symptomatic cases may improve outcomes. Further research to determine any pathophysiological basis for poor outcomes in symptomatic men is warranted.

Interleukin-17 promotes prostate cancer via MMP7-induced epithelial-to-mesenchymal transition

Chronic inflammation has been associated with a variety of human cancers including prostate cancer. Interleukin-17 (IL-17) is a critical pro-inflammatory cytokine, which has been demonstrated to promote development of prostate cancer, colon cancer, skin cancer, breast cancer, lung cancer, and pancreas cancer. IL-17 promotes prostate adenocarcinoma with a concurrent increase of matrix metalloproteinase 7 (MMP7) expression in mouse prostate. Whether MMP7 mediates IL-17’s action and the underlying mechanisms remain unknown. We generated Mmp7 and Pten double knockout (Mmp7^−/− in abbreviation) mouse model and demonstrated that MMP7 promotes prostate adenocarcinoma through induction of epithelial-to-mesenchymal transition (EMT) in Pten-null mice. MMP7 disrupted E-cadherin/β-catenin complex to up-regulate EMT transcription factors in mouse prostate tumors. IL-17 receptor C and Pten double knockout mice recapitulated the weak EMT characteristics observed in Mmp7^−/− mice. IL-17 induced MMP7 and EMT in human prostate cancer LNCaP, C4-2B, and PC-3 cell lines, while siRNA knockdown of MMP7 inhibited IL-17-induced EMT. Compound III, a selective MMP7 inhibitor, decreased development of invasive prostate cancer in Pten single knockout mice. In human normal prostates and prostate tumors, IL-17 mRNA levels were positively correlated with MMP7 mRNA levels. These findings demonstrate that MMP7 mediates IL-17’s function in promoting prostate carcinogenesis through induction of EMT, indicating IL-17-MMP7-EMT axis as potential targets for developing new strategies in the prevention and treatment of prostate cancer.

Circulating Beta-2 Microglobulin and Risk of Cancer: The Atherosclerosis Risk in Communities Study (ARIC)

BACKGROUND

Serum β-2 microglobulin (B2M), a major histocompatibility complex class I molecule that is a biomarker of kidney filtration and increased cell turnover, is elevated at the time of diagnosis in hematological and some solid cancers. However, serum B2M was not examined prospectively as a marker for cancer risk. We hypothesized that in a population without a prior cancer diagnosis, serum B2M is associated with risk of cancer (n = 2,436), including colorectal (n = 255), lung (n = 298), breast (n = 424), and prostate (n = 524) cancers, and hematological (n = 176) malignancies.

METHODS

The analytical cohort (n = 12,300) was followed for incident cancers from 1990 through 2006. B2M (range, 0.9-57.8 mg/L) was measured in stored serum collected in 1990-1992. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals for cancer incidence and mortality in relation to quartiles of B2M.

RESULTS

Adjusting for age, sex, race, center, education, body mass index, smoking, aspirin, and hormone therapy (in women) and comparing highest to lowest B2M quartiles, HRs were 1.25 (1.06-1.47; Ptrend = 0.002) for total cancer risk and 2.21 (1.32-3.70; Ptrend=0.001) for colorectal cancer risk, with similar HRs for colon and rectal cancers. These associations remained after adjustment for an inflammatory biomarker, C-reactive protein, and after excluding the first three years of follow-up. Significant associations were also observed for mortality from total, lung, and hematological cancers.

CONCLUSIONS

These findings provide the first evidence that higher serum B2M is associated with increased colorectal cancer risk.

IMPACT

This study supports B2M as a potential biomarker for colorectal cancer risk. Cancer Epidemiol Biomarkers Prev; 25(4); 657-64. ©2016 AACR.

A Perspective on Prostate Carcinogenesis and Chemoprevention

In this perspective, modifiable carcinogenic factors for the prostate are summarized. This is followed by a discussion of how current knowledge about causation of prostate cancer and chemoprevention of prostate cancer can be used to develop preventive strategies. Prostate cancer is a slowly developing cancer which offers opportunities for preventive interventions. Only a few randomized clinical trials of prostate cancer prevention have been completed. The SELECT study with selenium and vitamin E did not find protective effects, but in two trials with 5α-reductase inhibitors risk was reduced about 25%, showing that chemoprevention is possible and indicating that the androgen receptor is a suitable target. Besides smoking cessation and reduction of obesity, there are no known dietary or life style interventions that will have a major impact on prostate cancer risk. Inflammation of the prostate is an attractive target and aspirin may be a promising candidate agent, but has not been addressed yet in preclinical and clinical studies. Antioxidants other than selenium and vitamin E are unlikely to be very effective and data on several dietary supplements are not encouraging. More candidate agents need to be identified and tested in relevant and adequate preclinical models and Phase II trials that have predictive value for outcome of Phase III randomized studies. Doing this will require a systematic approach comparing preclinical and clinical study outcomes to determine their predictive value of preventive efficacy.

Polymorphisms of an innate immune gene, toll-like receptor 4, and aggressive prostate cancer risk: a systematic review and meta-analysis

BACKGROUND

Toll-like receptor 4 (TLR4) is one of the best known TLR members expressed on the surface of several leukocytes and tissue cells and has a key function in detecting pathogen and danger-associated molecular patterns. The role of TLR4 in the pathophysiology of several age-related diseases is also well recognized, such as prostate cancer (PCa). TLR4 polymorphisms have been related to PCa risk, but the relationship between TLR4 genotypes and aggressive PCa risk has not been evaluated by any systematic reviews.

METHODS

We performed a systematic review and meta-analysis of candidate-gene and genome-wide association studies analyzing this relationship and included only white population. Considering appropriate criteria, only nine studies were analyzed in the meta-analysis, including 3,937 aggressive PCa and 7,382 controls.

RESULTS

Using random effects model, no significant association was found in the ten TLR4 SNPs reported by at least four included studies under any inheritance model (rs2737191, rs1927914, rs10759932, rs1927911, rs11536879, rs2149356, rs4986790, rs11536889, rs7873784, and rs1554973). Pooled estimates from another ten TLR4 SNPs reported by three studies also showed no significant association (rs10759930, rs10116253, rs11536869, rs5030717, rs4986791, rs11536897, rs1927906, rs913930, rs1927905, and rs7045953). Meta-regression revealed that study type was not a significant source of between-study heterogeneity.

CONCLUSIONS

TLR4 polymorphisms were not significantly associated with the risk of aggressive PCa.

A critical review of the epidemiology of Agent Orange/TCDD and prostate cancer

To inform risk assessment and regulatory decision-making, the relationship between 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and prostate cancer requires clarification. This article systematically and critically reviews the epidemiologic evidence on the association between exposure to TCDD or Agent Orange, a TCDD-contaminated herbicide used during the Vietnam War, and prostate cancer risk. Articles evaluated include 11 studies of three cohorts, four case-control or cross-sectional studies, and three case-only studies of military veterans with information on estimated Agent Orange or TCDD exposure; 13 studies of seven cohorts, one case-control study, and eight proportionate morbidity or mortality studies of Vietnam veterans without information on Agent Orange exposure; 11 cohort studies of workers with occupational exposure to TCDD; and two studies of one community cohort with environmental exposure to TCDD. The most informative studies, including those of Vietnam veterans involved in Agent Orange spraying or other handling, herbicide manufacturing or spraying workers with occupational TCDD exposure, and community members exposed to TCDD through an industrial accident, consistently reported no significant increase in prostate cancer incidence or mortality. Only some potentially confounded studies of Vietnam veterans compared with the general population, studies with unreliable estimates of Agent Orange exposure, and analyses of selected subgroups of Vietnam veterans reported positive associations. Overall, epidemiologic research offers no consistent or convincing evidence of a causal relationship between exposure to Agent Orange or TCDD and prostate cancer. More accurate exposure assessment is needed in large epidemiologic studies to rule out a causal association more conclusively.

Genetic variation across C-reactive protein and risk of prostate cancer

BACKGROUND

Inflammation has been hypothesized to play an important etiological role in the initiation or progression of prostate cancer. Circulating levels of the systemic inflammation marker C-reactive protein (CRP) have been associated with increased risk of prostate cancer. We investigated the role of genetic variation in CRP and prostate cancer, under the hypothesis that variants may alter risk of disease.

METHODS

We undertook a case-control study nested within the prospective Physicians' Health Study among 1,286 men with incident prostate cancer and 1,264 controls. Four single-nucleotide polymorphisms (SNPs) were selected to capture the common genetic variation across CRP (r(2)  > 0.8). We used unconditional logistic regression to assess the association between each SNP and risk of prostate cancer. Linear regression models explored associations between each genotype and plasma CRP levels.

RESULTS

None of the CRP SNPs were associated with prostate cancer overall. Individuals with one copy of the minor allele (C) in rs1800947 had an increased risk of high-grade prostate cancer (OR: 1.7; 95% CI: 1.1-2.8), and significantly lower mean CRP levels (P-value <0.001), however, we found no significant association with lethal disease. Mean CRP levels were significantly elevated in men with one or two copies of the minor allele in rs3093075 and rs1417939, but these were unrelated to prostate cancer risk.

CONCLUSION

Our findings suggest that SNPs in the CRP gene are not associated with risk of overall or lethal prostate cancer. Polymorphisms in CRP rs1800947 may be associated with higher grade disease, but our results require replication in other cohorts.

Differences in characteristics of men with localised prostate cancer who demonstrate low, intermediate or high prostate-specific antigen velocity

BACKGROUND

Current diagnostic tools are inadequate for reliable prediction of prostate cancer (PCa) aggressiveness in patients with localised disease. This results in many patients being exposed to potentially unnecessary invasive treatment and its associated morbidities. In order to develop appropriate treatment strategies, it is essential to understand the differences between patients who will develop aggressive disease and those who will not.

METHODS

A longitudinal study was conducted in men with localised PCa on active surveillance for their disease in which 140 subjects were followed every 3 months for up to 5 years. Change in prostate-specific antigen (PSA) over time (PSA velocity) was used as a marker for PCa progression. Subjects were categorised as slow, intermediate and fast progressors based on tertiles of PSA velocity. Differences in baseline markers were investigated using logistic regressions. Two approaches were used, slow progressors were compared with fast progressors (model 1) and slow progressors were compared with combination of intermediate and fast progressors (model 2).

RESULTS

Aspirin was negatively associated with high PSA velocity in model 1 (odds ratio (95% confidence interval): 0.24 (0.06, 0.94), P-value = 0.04) and model 2 (odds ratio = 0.22 (0.08, 0.59), P-value = 0.003), whereas smoking was positively associated with high PSA velocity in model 1 (1.03 (0.92, 1.13), P-value = 0.01).

CONCLUSIONS

These findings highlight the role of aspirin and smoking in PCa progression. They have potential towards risk stratification as well as PCa prevention and hence need to be investigated further.

Polymorphisms in genes related to inflammation, NSAID use, and the risk of prostate cancer among Danish men

The etiology of prostate cancer (PC) remains mostly unknown, but increasing evidence suggests that chronic inflammation in the prostate is associated with an increased risk of PC. Epidemiological studies have suggested that use of nonsteroidal anti-inflammatory drugs (NSAIDs) may protect against PC. Inborn variations in genes involved in the inflammatory response may modulate the risk of PC and interact with NSAIDs. The aims of this study were 1) to evaluate whether polymorphisms and haplotypes of the inflammation-related genes COX-2, Il1B, NFKB1, and PPARG are associated with risk of PC; 2) to investigate gene-environment interactions between polymorphisms and NSAID use; and 3) to examine whether the studied polymorphisms were associated with the aggressiveness of PC. The study population consisted of 370 cases of PC and 370 risk-set matched (age) controls nested within the prospective Danish "Diet, Cancer, and Health" cohort. Carriers of the variant deletion allele of NFKB1 -94ins/delATTG had a tendency toward a reduced risk of PC (incidence rate ratio (IRR), 0.73; 95% confidence interval (CI) 0.52-1.04). A lowered risk for PC was also found for carriers of variant allele NFKB1 -94ins/delATTG among non-users of NSAIDs (IRR 0.68; 95% CI 0.47-0.99), for non-aggressive disease (IRR 0.64; 95% CI 0.42-0.99), and among men with a body mass index above 30 kg/m(2) (IRR 0.56; 95% CI 0.27-1.16), although the latter estimate was based on small numbers. A similar pattern was seen for the variant C allele of the COX-2 +8473T→C polymorphism. No apparent association with PC was observed for the other studied polymorphisms. Our study did not indicate that chronic inflammation is a major risk factor for aggressive PC.

Thirty years of research on infection and prostate cancer: no conclusive evidence for a link. A systematic review

BACKGROUND

The potential role of genitourinary infection in the etiology of prostate cancer (CaP) has been extensively investigated for 30 years. Two basic approaches have been used: tissue-based methods (polymerase chain reaction, immunohistochemistry, and in situ hybridization) and serologic assays (enzyme-linked immunosorbent assay, immunofluorescence, etc.). The objective of this review was to answer the question of whether infection of the male genitourinary tract may have a role in the etiology of CaP.

MATERIALS AND METHODS

We have carried out a systematic review of the evidence that was published in the MEDLINE/PubMed database until December 2011. The search terms included "prostate cancer," "infection," and the explicit names of the various infectious agents. Additional studies were identified using a reference search. A total of 74 papers were included in the review, which cover the following infectious agents: human papillomavirus, cytomegalovirus, herpes simplex virus, Epstein-Barr virus, human herpesvirus, BK virus, JC virus, chlamydia, mycoplasma, ureaplasma, trichomonas, neisseria, treponema, Propionibacterium acnes, xenotropic murine leukemia virus-related virus and Candida albicans.

RESULTS

Despite the variable study designs and methodological approaches that were used, most of the pathogens that were studied were unlikely to be directly involved in prostate carcinogenesis.

CONCLUSIONS

The role of infection in the etiology of CaP has yet to be determined despite 30 years of research efforts. A discovery of an infectious agent that is associated with CaP would be of great medical importance; however, such a link would have to be firmly established before impacting on patient care.

Prostate involvement during sexually transmitted infections as measured by prostate-specific antigen concentration

Background:

We investigated prostate involvement during sexually transmitted infections by measuring serum prostate-specific antigen (PSA) as a marker of prostate infection, inflammation, and/or cell damage in young, male US military members.

Methods:

We measured PSA before and during infection for 299 chlamydia, 112 gonorrhoea, and 59 non-chlamydial, non-gonococcal urethritis (NCNGU) cases, and 256 controls.

Results:

Chlamydia and gonorrhoea, but not NCNGU, cases were more likely to have a large rise (⩾40%) in PSA than controls (33.6%, 19.1%, and 8.2% vs 8.8%, P<0.0001, 0.021, and 0.92, respectively).

Conclusion:

Chlamydia and gonorrhoea may infect the prostate of some infected men.

Statins and prostate cancer: molecular and clinical aspects

The field of the potential applications of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) beyond their unambiguous cardiovascular beneficial effects is steadily increasing. In this regard, statins have also been shown to possess anti-inflammatory, immunomodulatory, antioxidant and growth inhibitory properties. Regarding their role in carcinogenesis, both preclinical and clinical studies report conflicting results. Intriguingly, accumulating evidence suggests that statins may relate to decreased prostate cancer incidence and recurrence risk. However, data from clinical studies seem to be still weak and are confounded by several factors. Nonetheless, preclinical data suggest that statins might exert a chemopreventive role against prostate cancer by inhibiting the proliferation and inducing apoptosis of prostate cancer cells and also inhibiting angiogenesis, inflammation and metastasis. Cholesterol lowering as well as statin pleiotropy through inhibition of the synthesis of isoprenoids have both been implicated in their anticancer properties. In this review, we discuss the preclinical and clinical evidence supporting the preventive or potentially harmful effects of statins on prostate tumourigenesis and conclude that statins should not be recommended for the prevention of prostate cancer development or progression based on the current data.

IL-6 promotes prostate tumorigenesis and progression through autocrine cross-activation of IGF-IR

As an established mediator of inflammation, IL-6 is implicated to facilitate prostate cancer progression to androgen independence through transactivation of the androgen receptor. However, whether IL-6 plays a causative role in de novo prostate tumorigenesis was never investigated. We now provide the first evidence that IL-6 can induce tumorigenic conversion and further progression to an invasive phenotype of non-tumorigenic benign prostate epithelial cells. Moreover, we find that paracrine IL-6 stimulates autocrine IL-6 loop and autocrine activation of IGF-IR to confer the tumorigenic property and that activation of STAT3 is critical in these processes. Inhibition of STAT3 activation or IGF-IR signaling suppresses IL-6-mediated malignant conversion and the associated invasive phenotype. Inhibition of STAT3 activation suppresses IL-6-induced upregulation of IGF-IR and its ligands IGF-I and IGF-II. These findings indicate IL-6 signaling cooperates with IGF-IR signaling in the prostate microenvironment to promote prostate tumorigenesis and progression to aggressiveness. Our findings suggest that STAT3 and IGF-IR may represent potential effective targets for prevention or treatment of prostate cancer.

Dietary zinc and prostate cancer in the TRAMP mouse model

Circumstantial evidence indicates that zinc may have an important role in the prostate. Total zinc levels in the prostate are 10 times higher than in other soft tissues. Zinc concentrations in prostate epithethial cancer cells are decreased significantly. Zinc supplementation for prevention and treatment of prostate cancer in humans has yielded controversial results. No studies have been reported in animal models to show the effect of zinc supplementation on prevention of prostate cancer, thus far. In this study, we have examined the effect of zinc supplementation on development of prostate cancer in a TRAMP mouse model. Results from our study indicate that dietary zinc plays an important role in prostate carcinogenesis. Tumor weights were significantly higher when the dietary zinc intake was either deficient or high in comparison to normal zinc intake level, suggesting that an optimal dietary zinc intake may play a protective role against prostate cancer. Further, our studies also showed decreased insulin-like growth factor (IGF)-1 and IGF-1/IGF binding protein-3 ratio in normal zinc-supplemented animals, suggesting that zinc may modulate IGF-1 metabolism in relation to carcinogenesis. We conclude that optimal prostate zinc concentration has a protective role against cancer.

Effect of aspirin, other NSAIDs, and statins on PSA and PSA velocity

BACKGROUND

Aspirin, other non-steroidal anti-inflammatory drugs (NSAIDs), and statins have been associated with lower risk of prostate cancer and its progression, though results have been inconsistent.

METHODS

Data from 140 men with prostate cancer enrolled in a Phase 2 clinical trial of selenium to prevent prostate cancer progression were analyzed to determine association between aspirin, other NSAIDs, or statin use with baseline serum prostate-specific antigen (PSA) levels and PSA velocity (rate of PSA change over time) using repeated measures over an average follow-up time of 3.2 years. Multiple linear regression and mixed effects models were used to model the association of medication use with PSA at baseline and with PSA velocity, respectively.

RESULTS

Baseline PSA levels were significantly lower in aspirin users compared to non-users (5.17 ng/ml vs. 7.58 ng/ml, P = 0.001). This association was statistically significant in never smokers (aspirin users vs. non-users: 4.19 ng/ml vs. 8.24 ng/ml, P = 0.004) but not in ever smokers (aspirin users vs. non-users: 5.52 ng/ml vs. 7.3 ng/ml, P = 0.101). Statin and other NSAID use was not associated with baseline PSA. Aspirin, statin, or other NSAID use at baseline demonstrated a non-significant negative association with PSA velocity.

CONCLUSION

These findings support an effect of aspirin use on PSA, particularly among never smokers. However, they do not suggest a protective effect on the disease and support previous findings that aspirin use may mask accurate measurement of PSA warranting consideration of washout procedures prior to testing.

Propionibacterium acnes infection induces upregulation of inflammatory genes and cytokine secretion in prostate epithelial cells

Background

The immune stimulating bacterium Propionibacterium acnes is a frequent colonizer of benign and malignant prostate tissue. To understand the pathogenesis of the earliest phase of this infection, we examined the P. acnes triggered immune response in cultivated prostate epithelial cells.

Results

Prostate epithelial cells are triggered to secrete IL-6, IL-8 and GM-CSF when infected with P. acnes. The secretion of cytokines is accompanied by NFκB related upregulation of the secreted cytokines as well as several components of the TLR2-NFκB signaling pathway.

Conclusions

P. acnes has potential to trigger a strong immune reaction in the prostate glandular epithelium. Upon infection of prostate via the retrograde urethral route, the induced inflammatory reaction might facilitate bacterial colonization deeper in the prostate tissue where persistent inflammation may impact the development of prostate diseases as hyperplasia and/or malignancy.

C-reactive protein, interleukin-6, and prostate cancer risk in men aged 65 years and older

Inflammation is believed to play a role in prostate cancer (PCa) etiology, but it is unclear whether inflammatory markers C-reactive protein (CRP) and interleukin-6 (IL-6) associate with PCa risk in older men. Using Cox regression, we assessed the relationship between baseline concentrations of CRP and IL-6 and the subsequent PCa risk in the Cardiovascular Health Study, a population-based cohort study of mostly European American men of ages >64 years (n = 2,234; mean follow-up = 8.7 years; 215 incident PCa cases). We also tested associations between CRP and IL-6 tagSNPs and PCa risk, focusing on SNPs that are known to associate with circulating CRP and/or IL-6. Neither CRP nor IL-6 blood concentrations was associated with PCa risk. The C allele of IL-6 SNP rs1800795 (-174), a known functional variant, was associated with increased risk in a dominant model (HR = 1.44; 95% CI = 1.03-2.01; p = 0.03), but was not statistically significant after accounting for multiple tests (permutation p = 0.21). Our results suggest that circulating CRP and IL-6 do not influence PCa risk. SNPs at the CRP locus are not associated with PCa risk in this cohort, while the association between rs1800795 and PCa risk warrants further investigation.

Sexually transmissible infections and prostate cancer risk

BACKGROUND

Sexually transmissible infections (STI) have been variably associated with increased risks of prostate cancer, largely in case-control studies.

METHODS

In the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we examined risk of prostate cancer in relation to serum antibodies to Chlamydia trachomatis, human papillomavirus-16 and -18, herpes simplex virus-2, cytomegalovirus, and human herpesvirus-8 in 868 cases (765 Whites and 103 Blacks) and 1,283 controls matched by race, age, time since initial screening, and year of blood draw; all blood samples were collected at least 1 year before prostate cancer diagnosis, except for 43 Black cases. We also assessed risk associated with self-reported history of syphilis and gonorrhea.

RESULTS

Prevalences of the 7 STIs among controls were weakly correlated, and all were more frequent among Blacks than Whites, except for human herpesvirus-8. Among Whites, prostate cancer risk was not significantly associated with the individual infections or with their number (P(trend) = 0.1); however, men with one or more STI had slightly higher risk (odds ratio, 1.3; 95% confidence interval, 1.0-1.6). Among Blacks, excess risk was associated with IgA antibody to C. trachomatis (odds ratio, 2.1; 95% confidence interval, 1.2-3.6).

CONCLUSION

This large prospective study of prostate cancer shows no consistent association with specific STIs and a borderline association with any versus none. Whether a shared response or correlated infection not directly measured underlies the weak association requires further study.

The effect of dietary supplementation with limonene or myo-inositol on the induction of neoplasia and matrix metalloproteinase and plasminogen activator activities in accessory sex organs of male Lobund-Wistar rats

Prostate cancer, the most prevalent non-cutaneous cancer in men, is associated with increased age. This suggests that dietary chemopreventive measures could be effective in delaying the onset or decreasing the severity of the disease. We utilized the Lobund-Wistar rat nitrosomethylurea induced, testosterone promoted (NMU-T) model of male sex accessory gland cancer to test the potential chemopreventive effects of myo-inositol and limonene on tumor incidence and associated protease activities. Tumors were found to arise in the seminal vesicles and dorsal and anterior prostate lobes. There were also some tumors that appeared to arise in both the seminal vesicles and anterior prostate, and in some cases the tissue of origin was not clear. The distribution of tumors as to site of origin in limonene or myo-inositol treated animals did not vary from that of the starch fed control animals, and the number of animals presenting with metastases did not vary significantly between treatment groups. There was a statistically significant delay in onset of tumors in myo-inositol, but not limonene fed rats, at 10 months post-induction of carcinogenesis; however, at 12 and 15 months this was not significant. The ventral prostate and seminal vesicles expressed pro-MMP-2 and plasminogen activator (PA) activities. Based on sensitivity to amiloride, the PA activities were predominately urokinase (uPA) in the ventral prostate and a mixture of tissue-type activator (tPA) and uPA in the seminal vesicles of non-treated rats. Sex accessory gland tumors, and metastases, expressed increased levels PA and pro- and active forms of MMP-2 and -9. The PA activities of the tumors were a mixture of uPA and tPA. There was no difference in the levels of these protease activities based on the tissue of tumor origin, nor in tumor vs metastasis. These studies indicate that MMP and PA activities play a role in sex accessory gland tumor biology and that dietary supplementation with myo-inositol can delay but not ultimately prevent the development of such tumors.

Association between dietary fiber and markers of systemic inflammation in the Women's Health Initiative Observational Study

OBJECTIVE

Systemic inflammation may play an important role in the development of atherosclerosis, type 2 diabetes, and some cancers. Few studies have comprehensively assessed the direct relations between dietary fiber and inflammatory cytokines, especially in minority populations. Using baseline data from 1958 postmenopausal women enrolled in the Women's Health Initiative Observational Study, we examined cross-sectional associations between dietary fiber intake and markers of systemic inflammation (including serum high-sensitivity C-reactive protein [hs-CRP], interleukin-6 [IL-6], and tumor necrosis factor-alpha receptor-2 [TNF-alpha-R2]) in addition to differences in these associations by ethnicity.

METHODS

Multiple linear regression models were used to assess the relation between fiber intake and makers of systemic inflammation.

RESULTS

After adjustment for covariates, intakes of dietary fiber were inversely associated with IL-6 (P values for trend were 0.01 for total fiber, 0.004 for soluble fiber, and 0.001 for insoluble fiber) and TNF-alpha-R2 (P values for trend were 0.002 for total, 0.02 for soluble, and <0.001 for insoluble fibers). Although the samples were small in minority Americans, results were generally consistent with those found among European Americans. We did not observe any significant association between intake of dietary fiber and hs-CRP.

CONCLUSION

These findings lend support to the hypothesis that a high-fiber diet is associated with lower plasma levels of IL-6 and TNF-alpha-R2. Contrary to previous reports, however, there was no association between fiber and hs-CRP among postmenopausal women. Future studies on the influence of diet on inflammation should include IL-6 and TNF-alpha-R2 and enroll participants from ethnic minorities.

Cyclic adenosine monophosphate differentiated beta-endorphin neurons promote immune function and prevent prostate cancer growth

Pituitary adenylate cyclase-activating peptide (PACAP), a cAMP-activating agent, is highly expressed in the hypothalamus during the period when many neuroendocrine cells become differentiated from the neural stem cells (NSCs). Activation of the cAMP system in rat hypothalamic NSCs differentiated these cells into beta-endorphin (BEP)-producing neurons in culture. When these in vitro differentiated neurons were transplanted into the paraventricular nucleus (PVN) of the hypothalamus of an adult rat, they integrated well with the surrounding cells and produced BEP and its precursor gene product, proopiomelanocortin (POMC). Animals with BEP cell transplants demonstrated remarkable protection against carcinogen induction of prostate cancer. Unlike carcinogen-treated animals with control cell transplants, rats with BEP cell transplants showed rare development of glandular hyperplasia, prostatic intraepithelial neoplasia (PIN), or well differentiated adenocarcinoma with invasion after N-methyl-N-nitrosourea (MNU) and testosterone treatments. Rats with the BEP neuron transplants showed increased natural killer (NK) cell cytolytic function in the spleens and peripheral blood mononuclear cells (PBMCs), elevated levels of antiinflammatory cytokine IFN-gamma, and decreased levels of inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) in plasma. These results identified a critical role for cAMP in the differentiation of BEP neurons and revealed a previously undescribed role of these neurons in combating the growth and progression of neoplastic conditions like prostate cancer, possibly by increasing the innate immune function and reducing the inflammatory milieu.

Acne and risk of prostate cancer

In a recent study, prostatectomy specimens from which Propionibacterium acnes was cultured were more likely to have inflammation than culture-negative specimens or specimens positive for other bacteria, leading the authors to hypothesize that P. acnes-mediated inflammation may contribute to prostate carcinogenesis. To indirectly explore associations between P. acnes and prostate cancer, we investigated severe acne, as measured by tetracycline use for 4 or more years, in relation to incident prostate cancer in the Health Professionals Follow-up Study. On the 1992 follow-up questionnaire, participants were asked whether they had ever used "tetracycline for at least 2 months at a time (e.g., for acne or other reason)" and their duration of use. Prostate cancer diagnoses were ascertained on each subsequent biennial questionnaire and confirmed by medical record review. Between 1992 and 2002, 2,147 cases of prostate cancer were reported among 34,629 eligible participants. Men who used tetracycline for 4 or more years had a significantly higher risk of prostate cancer (16 cases, 1,569 person-years) than men who did not use tetracycline (2,071 cases, 304,822 person-years, multivariable-adjusted RR = 1.70, 95% CI: 1.03-2.80). Although intriguing, this finding should be viewed cautiously because of the small number of exposed cases, indirect assessment of severe acne, and complex etiology of acne, which is not limited to P. acnes infection. Therefore, additional biologic and epidemiologic studies are necessary to determine and elucidate the possible role of P. acnes infection in prostate carcinogenesis.