Genetic variability in inflammation pathways and prostate cancer risk

Association between monocyte-to-lymphocyte ratio and prostate cancer in the U.S. population: a population-based study

Introduction

Monocyte-to-lymphocyte ratio (MLR) is a convenient and noninvasive inflammatory biomarker, and inflammation has been reported to be associated with prostate cancer (PCa). Our objective was to ascertain any possible correlation between PCa and MLR.

Methods

We utilized data from the 1999-2020 cycles of the National Health and Nutrition Examination Survey (NHANES) regarding MLR and PCa. The independent associations of MLR and other inflammatory biomarkers (platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), system inflammation response index (SIRI), and aggregate index of systemic inflammation (AISI)) with PCa was investigated using weighted multivariate logistic regression and generalized additive models. Receiver operating characteristic (ROC) curves were conducted to evaluate and contrast their diagnostic capabilities.

Results

The analysis we conducted comprised 25,367 persons in total. The mean MLR was 0.31 ± 0.14. The prevalence of PCa was 3.1%. A positive association was found between MLR and PCa (OR = 2.28; 95% CI: 1.44, 3.62). According to the interaction tests, age, body mass index (BMI), hypertension, diabetes, and smoking status did not significantly impact the relationship between MLR and PCa (all p for interaction >0.05). ROC analysis showed that MLR had a stronger discriminative ability and accuracy in predicting PCa than other inflammatory biomarkers (NLR, SII, AISI, PLR, and SIRI).

Conclusion

MLR might be better than other inflammatory biomarkers (NLR, SIRI, AISI, PLR, and SII) in predicting PCa. American adults who have elevated levels of MLR, NLR, PLR, SII, and AISI should be aware that they have a greater risk of PCa.

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.

The Effects of Ultrasound and Arsenic Trioxide on Neurogliocytoma Cells and Secondary Activation of Macrophages

Aims and Background

As a new technique for clinical therapeutics, ultrasound has synergistic effects on traditional chemotherapy. Arsenic trioxide (AS2O3), an apoptosis-inducing drug, has successfully been used in the treatment of some tumor types in recent years. Macrophages have both positive and negative effects on the occurrence and development of tumors. The aim of this study was to observe the effects of ultrasound and AS2O3 on a glioma cell line and the secondary activation of macrophages by cell death, in order to provide a theoretical basis for the clinical application of AS2O3 and ultrasound in glioma treatment.

Methods

Different AS2O3 concentrations were used solely or combined with ultrasound in rat glioma C6 cells to induce cell death. The degree of C6 cell death was determined by AnnexinV-FITC and PI double staining. The intracellular arsenium concentration and the release of lactate dehydrogenase (LDH) from C6 cells were also measured. The supernatant of C6 cells was then used to stimulate macrophages. Finally the activation of NF-κB and the secretion of TNF-α and TGF-β1 by macrophages were determined.

Results

The cell death increase in the group where ultrasound was used together with AS2O3 was significantly higher than that obtained by either ultrasound or AS2O3. The increase was also significantly higher than the sum of the increases in the ultrasound and the AS2O3 only groups. At the same AS2O3 concentration, additional treatment with ultrasound can significantly increase the intracellular arsenium concentration. The release of LDH from C6 cells showed a close, direct correlation with late apoptosis and necrosis, but did not exhibit an obvious correlation with early apoptosis. The activation of NF-κB and the secretion of TNF-α and TGF-β1 in macrophages also showed a close direct correlation with late apoptosis and necrosis.

Conclusions

This in vitro study demonstrates that ultrasound may synergistically enhance the cell-killing effect by promoting AS2O3 to enter the C6 cells. Macrophages may be activated by killed C6 cells, especially by necrotic C6 cells.

Scavenger Receptors: Emerging Roles in Cancer Biology and Immunology

Scavenger receptors constitute a large family of evolutionally conserved protein molecules that are structurally and functionally diverse. Although scavenger receptors were originally identified based on their capacity to scavenge modified lipoproteins, these molecules have been shown to recognize and bind to a broad spectrum of ligands, including modified and unmodified host-derived molecules or microbial components. As a major subset of innate pattern recognition receptors, scavenger receptors are mainly expressed on myeloid cells and function in a wide range of biological processes, such as endocytosis, adhesion, lipid transport, antigen presentation, and pathogen clearance. In addition to playing a crucial role in maintenance of host homeostasis, scavenger receptors have been implicated in the pathogenesis of a number of diseases, e.g., atherosclerosis, neurodegeneration, or metabolic disorders. Emerging evidence has begun to reveal these receptor molecules as important regulators of tumor behavior and host immune responses to cancer. This review summarizes our current understanding on the newly identified, distinct functions of scavenger receptors in cancer biology and immunology. The potential of scavenger receptors as diagnostic biomarkers and novel targets for therapeutic interventions to treat malignancies is also highlighted.

Senescent remodeling of the innate and adaptive immune system in the elderly men with prostate cancer

Despite years of intensive investigation that has been made in understanding prostate cancer, it remains a major cause of death in men worldwide. Prostate cancer emerges from multiple alterations that induce changes in expression patterns of genes and proteins that function in networks controlling critical cellular events. Based on the exponential aging of the population and the increasing life expectancy in industrialized Western countries, prostate cancer in the elderly men is becoming a disease of increasing significance. Aging is a progressive degenerative process strictly integrated with inflammation. Several theories have been proposed that attempt to define the role of chronic inflammation in aging including redox stress, mitochondrial damage, immunosenescence, and epigenetic modifications. Here, we review the innate and adaptive immune systems and their senescent remodeling in elderly men with prostate cancer.

Intratumoral inflammation is associated with more aggressive prostate cancer

PURPOSE

Inflammation may play a role in the development and progression of many cancers, including prostate cancer. We sought to test whether histological inflammation within prostate cancer was associated with more aggressive disease.

METHODS

The slides of prostatectomy specimens were reviewed by a board-certified pathologist on 287 men from a Veterans Affairs Medical Center treated with radical prostatectomy from 1992 to 2004. The area with the greatest tumor burden was scored in a blinded manner for the degree of inflammation: absent, mild, or marked. We used logistic and Cox proportional hazards regression analysis to examine whether categorically coded inflammation score was associated with adverse pathology and biochemical progression, respectively.

RESULTS

No inflammation was found in 49 men (17%), while 153 (53%) and 85 (30%) had mild and marked inflammation. During a median follow-up of 77 months, biochemical recurrence occurred among 126 (44%) men. On multivariate analysis, more inflammation was associated with greater risk of positive margins, capsular penetration, and seminal vesicle invasion (all p < 0.05). Marked inflammation was associated with increased PSA recurrence risk when adjusting for preoperative features only (HR 2.08, 95% CI 1.02-4.24), but not after adjusting for pathologic features.

CONCLUSIONS

Inflammation within prostate cancer was associated with more advanced disease, although it is unclear whether aggressive disease caused increased inflammation or inflammation caused aggressive disease.

Identification of genetic risk associated with prostate cancer using ancestry informative markers

BACKGROUND

Prostate cancer (PCa) is a common malignancy and a leading cause of cancer death among men in the United States with African-American (AA) men having the highest incidence and mortality rates. Given recent results from admixture mapping and genome-wide association studies for PCa in AA men, it is clear that many risk alleles are enriched in men with West African genetic ancestry.

METHODS

A total of 77 ancestry informative markers (AIMs) within surrounding candidate gene regions were genotyped and haplotyped using Pyrosequencing in 358 unrelated men enrolled in a PCa genetic association study at the Howard University Hospital between 2000 and 2004. Sequence analysis of promoter region single-nucleotide polymorphisms (SNPs) to evaluate disruption of transcription factor-binding sites was conducted using in silico methods.

RESULTS

Eight AIMs were significantly associated with PCa risk after adjusting for age and West African ancestry. SNP rs1993973 (intervening sequences) had the strongest association with PCa using the log-additive genetic model (P=0.002). SNPs rs1561131 (genotypic, P=0.007), rs1963562 (dominant, P=0.01) and rs615382 (recessive, P=0.009) remained highly significant after adjusting for both age and ancestry. We also tested the independent effect of each significantly associated SNP and rs1561131 (P=0.04) and rs1963562 (P=0.04) remained significantly associated with PCa development. After multiple comparisons testing using the false discovery rate, rs1993973 remained significant. Analysis of the rs156113-, rs1963562-rs615382l and rs1993973-rs585224 haplotypes revealed that the least frequently found haplotypes in this population were significantly associated with a decreased risk of PCa (P=0.032 and 0.0017, respectively).

CONCLUSIONS

The approach for SNP selection utilized herein showed that AIMs may not only leverage increased linkage disequilibrium in populations to identify risk and protective alleles, but may also be informative in dissecting the biology of PCa and other health disparities.

Scavenger receptor class A ligands induce secretion of IL1β and exert a modulatory effect on the inflammatory activation of astrocytes in culture

Class-A scavenger receptor (SR-A) is expressed by microglia, and we show here that it is also expressed by astrocytes, where it participates on their inflammatory activation. Astrocytes play a key role on the inflammatory response of the central nervous system, secreting several soluble mediators like cytokines and radical species. Exposure to SR ligands activated MAPKs and NF-κB signaling and increased production of IL1β and nitric oxide (NO). IL1β classically an inflammatory cytokine surprisingly did not increase but inhibited LPS+IFNγ-induced NO production by astrocytes. Our results suggest that SRs expressed by astrocytes participate in the modulation of inflammatory activation.

Inflammation-associated regulation of the macrophage inhibitory cytokine (MIC-1) gene in prostate cancer

Macrophage inhibitory cytokine-1 (MIC-1), also known as prostate-derived factor (PDF), is a molecule of the TGF-β superfamily and has been associated with the progression of various types of diseases including prostate cancer. Initially identified from activated macrophages, the MIC-1 gene may provide a potential link between inflammation and prostate cancer. In this context, we performed MIC-1 expression analysis using mouse prostate tissues to determine whether there was any correlation with age and inflammation. Reverse transcription PCR analysis on RNA samples isolated from prostate lobes from prostate-specific antigen transgenic mice of varying ages revealed that MIC-1 gene expression is extremely low to non-detectable in the prostate tissues obtained from young mice, while its expression increases in the prostate tissues harvested from elderly mice. Increased MIC-1 gene expression in the mouse prostate was found to be associated with an increased level of infiltrating lymphocytes. To confirm this observation, we showed that inflammation-associated cytokines (IL-1β and TNF-α) significantly upregulate the secretion of the MIC-1 protein in a human prostate cancer cell line (LNCaP cells), while cytokines IL-6 and granulocyte macrophage colony-stimulating factor were less effective. Taken together, these data indicated that inflammation-associated cytokines may play a critical role in the functional regulation of the MIC-1 gene in the early stages of prostate cancer development. More studies are required to understand the biological activity of MIC-1 gene regulation in the development and progression of prostate cancer.

Interactions among genes, tumor biology and the environment in cancer health disparities: examining the evidence on a national and global scale

Cancer incidence and mortality rates show great variations across nations and between population groups. These variations are largely explained by differences in age distribution, diet and lifestyle, access to health care, cultural barriers and exposure to carcinogens and pathogens. Cancers caused by infections are significantly more common in developing than developed countries, and they overproportionally affect immigrant populations in the USA and other countries. The global pattern of cancer is not stagnant. Instead, it is dynamic because of fluctuations in the age distribution of populations, improvements in cancer prevention and early detection in affluent countries and rapid changes in diet and lifestyle in parts of the world. For example, increased smoking rates have caused tobacco-induced cancers to rise in various Asian countries, whereas reduced smoking rates have caused these cancers to plateau or even begin to decline in Western Europe and North America. Some population groups experience a disproportionally high cancer burden. In the USA and the Caribbean, cancer incidence and mortality rates are excessively high in populations of African ancestry when compared with other population groups. The causes of this disparity are multifaceted and may include tumor biological and genetic factors and their interaction with the environment. In this review, we will discuss the magnitude and causes of global cancer health disparities and will, with a focus on African-Americans and selected cancer sites, evaluate the evidence that genetic and tumor biological factors contribute to existing cancer incidence and outcome differences among population groups in the USA.

Genetic polymorphisms in inflammation pathway genes and prostate cancer risk

BACKGROUND

Chronic inflammation is an important mechanism for the development and progression of prostate cancer (PC). To better understand the potential relationship between genes in the inflammation pathway and PC risk, we evaluated variants in 16 candidate genes.

METHODS

A total of 143 tagging and amino acid altering single nucleotide polymorphisms (SNPs) were genotyped in Caucasian and African American men participating in one of two population-based, case-control studies (n = 1,458 cases and 1,351 controls). The relative risk of PC was estimated using logistic and polytomous regression models.

RESULTS

Ten SNPs in seven genes (CXCL12, IL4, IL6, IL6ST, PTGS2, STAT3, and TNF) were nominally associated (P < 0.05) with risk of PC in Caucasians. The most significant effect on risk was seen with rs11574783 in the interleukin 6 signal transducer (IL6ST) gene (OR = 0.08, 95% CI: 0.01-0.63). Cumulatively, four SNPs in genes interleukin 4 (IL4), IL6ST, PTGS2, and signal transducer and activator of transcription 3 (STAT3) conferred a three-fold elevation in PC risk among men carrying the maximum number of high-risk alleles (OR = 2.97, 95% CI: 1.41-6.25, P(trend) = 0.0003). Risk estimates for seven SNPs varied significantly according to disease aggressiveness (P(homogeneity) < 0.05), with SNPs in AKT1, PIK3R1, and STAT3 independently associated with more aggressive PC; OR = 5.1 (95% CI: 2.29-11.40, P(trend) = 3.8 × 10(-5)) for carriers of all high-risk genotypes.

CONCLUSIONS

These results suggest that variants in genes within the inflammation pathway may play a role in the development of PC, however, further studies are needed to replicate our findings.

IMPACT

These results underline the potential importance of the inflammation pathway in PC development and progression.

Lack of association of IL-10 gene polymorphisms with prostate cancer: evidence from 11,581 subjects

Published data on the association between interleukin-10 (IL-10) gene polymorphisms and prostate cancer (PCa) are inconclusive. To derive a more precise estimation of the association, we conducted a meta-analysis. Data were collected from the following electronic databases: PubMed, Elsevier Science Direct, Excerpta Medica Database and Chinese Biomedical Literature Database, with the last report up to September 2010. The odds ratio (OR) and its 95% confidence interval (95%CI) were used to assess the strength of association. A total of 13 separate studies including 5503 cases and 6078 controls based on the search criteria were involved in this meta-analysis. Meta-analysis was performed for three IL-10 gene polymorphisms (rs1800896, rs1800871, and rs1800872). We found no association between IL-10 gene rs1800896 polymorphism and PCa in overall population (G versus A: OR=1.00, 95%CI=0.91-1.10, P=0.99; AG+GG versus AA: OR=1.18, 95%CI=0.97-1.43, P=0.10; GG versus AA+AG: OR=1.04, 95%CI=0.86-1.26, P=0.67). In subgroup analysis, similar results were found in Caucasian (G versus A: OR=0.99, 95%CI=0.84-1.18, P=0.92; AG+GG versus AA: OR=1.32, 95%CI=0.90-1.94, P=0.16; GG versus AA+AG: OR=1.07, 95%CI=0.89-1.28, P=0.48), and Asian (G versus A: OR=0.97, 95%CI=0.78-1.20, P=0.78; AG+GG versus AA: OR=1.07, 95%CI=0.79-1.45, P=0.65; GG versus AA+AG: OR=1.24, 95%CI=0.38-4.07, P=0.73) populations. We did not detect an association between IL-10 gene rs1800871 polymorphism and PCa in overall population (T versus C: OR=0.96, 95%CI=0.85-1.08, P=0.51; CT+TT versus CC: OR=0.94, 95%CI=0.80-1.11, P=0.48; TT versus CC+CT: OR=0.94, 95%CI=0.81-1.10, P=0.44). Similar results were found in Asian population (T versus C: OR=0.85, 95%CI=0.71-1.09, P=0.09; CT+TT versus CC: OR=0.72, 95%CI=0.52-1.17, P=0.05; TT versus CC+CT: OR=0.89, 95%CI=0.68-1.17, P=0.39). We found no association between IL-10 gene rs1800872 polymorphism and PCa in overall population (A versus C: OR=1.03, 95%CI=0.96-1.11, P=0.41; CA+AA versus CC: OR=1.04, 95%CI=0.92-1.17, P=0.56; AA versus CC+CA: OR=1.02, 95%CI=0.85-1.22, P=0.87). Similar results were found in Caucasian population (A versus C: OR=1.06, 95%CI=0.98-1.16, P=0.16; CA+AA versus CC: OR=1.07, 95%CI=0.85-1.35, P=0.57; AA versus CC+CA: OR=1.23, 95%CI=0.92-1.64, P=0.17). This meta-analysis suggests that there is no association between IL-10 gene rs1800896, rs1800871 and rs1800872 polymorphisms and PCa.

Just who is at risk? The ethics of environmental regulation

The willingness to view risk as part of daily life has vanished. A risk-averse mindset among environmental regulators engenders confusion between the ethics of intention and the ethics of consequence, leading to the elevation of the precautionary principle with unintended and often unfortunate outcomes. Environmental risk assessment is conservative, but the actual level of conservatism cannot be determined. High-end exposure assumptions and current toxicity criteria from the USEPA, based on linear extrapolation for carcinogens and default uncertainty factors for systemic toxicants, obscure the degree of conservatism in risk assessments. Ideally, one could choose a percentile of the target population to include within environmental standards, but this choice is complicated by the food, pharmaceutical and advertising industries, whose activities, inadvertent or not, often promote maladaptive and unhealthy lifestyle choices. There has lately been much discussion about background exposures and disease processes and their potential to increase the risk from environmental chemicals. Should these background exposures or disease processes, especially those associated with maladaptive individual choices, be included as part of a regulatory risk evaluation? A significant ethical question is whether environmental regulation should protect those pursuing a self-destructive lifestyle that may add to or synergize with otherwise innocuous environmental exposures. Choosing a target percentile of protection would provide an increased level of transparency and the flexibility to choose a higher or lower percentile if such a choice is warranted. Transparency and flexibility will lead to more responsive environmental regulation that balances protection of public health and the stewardship of societal resources.

Inflammatory genetic markers of prostate cancer risk

Prostate cancer is the most common cancer in Western society males, with incidence rates predicted to rise with global aging. Etiology of prostate cancer is however poorly understood, while current diagnostic tools can be invasive (digital rectal exam or biopsy) and/or lack specificity for the disease (prostate-specific antigen (PSA) testing). Substantial histological, epidemiological and molecular genetic evidence indicates that inflammation is important in prostate cancer pathogenesis. In this review, we summarize the current status of inflammatory genetic markers influencing susceptibility to prostate cancer. The focus will be on inflammatory cytokines regulating T-helper cell and chemokine homeostasis, together with the Toll-like receptors as key players in the host innate immune system. Although association studies indicating a genetic basis for prostate cancer are presently limited mainly due to lack of replication, larger and more ethnically and clinically defined study populations may help elucidate the true contribution of inflammatory gene variants to prostate cancer risk.

Decreased infiltration of macrophage scavenger receptor-positive cells in initial negative biopsy specimens is correlated with positive repeat biopsies of the prostate

Macrophage scavenger receptor (MSR)-positive inflammatory cells and tumor-associated macrophages (TAMs) have been reported to regulate the growth of various cancers. In this study, the infiltration of MSR-positive cells and TAMs was analyzed to predict the outcome of repeat biopsy in men diagnosed as having no malignancy at the first prostate biopsy. Repeat biopsy of the prostate was carried out in 92 patients who were diagnosed as having no malignancy at the first biopsy. Of these, 30 patients (32.6%) were positive for prostate cancer at the repeat biopsy. Tumor-associated macrophages and MSR-positive cells were immunohistochemically stained with mAbs CD68 and CD204, respectively. Six ocular measuring fields were chosen randomly under a microscope at x400 power in the initial negative biopsy specimens, and the mean TAM and MSR counts for each case were determined. No difference in TAM count was found between the cases with or without prostate cancer. By contrast, the MSR count in patients with cancer was significantly lower than that in patients without cancer at the repeat biopsy (P < 0.001). Logistic regression analysis indicated that the MSR count at first biopsy is a significantly better predictive factor for positive repeat biopsy than PSA velocity, interval between first and repeat biopsies, or TAM count. Decreased infiltration of MSR-positive cells in negative first biopsy specimens was correlated with positive findings in the repeat biopsy. The MSR count might be a good indicator for avoiding unnecessary repeat biopsies.

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.

The 4q27 locus and prostate cancer risk

Background

Chronic inflammation is considered to be implicated in the development of prostate cancer. In this study we are the first to investigate a potential association between variants in an autoimmune related region on chromosome 4q27 and prostate cancer risk. This region harbors two cytokine genes IL-2 and the recently described IL-21.

Methods

We genotyped six variants previously associated with autoimmune disease (namely rs13151961, rs13119723, rs17388568, rs3136534, rs6822844 and rs6840978) and one functional IL-2 promoter variant (rs2069762) for possible association with prostate cancer risk using the Australian Risk Factors for Prostate Cancer case-control Study.

Results

Overall, our results do not support an association between the seven variants at position 4q27 and prostate cancer risk. Per allele odds ratios (ORs) were not significantly different from 1 (all P-values = 0.06). However, we found suggestive evidence for a significant association between the presence of the rs13119723 variant (located in a protein of unknown function) and men with a family history of prostate cancer in first-degree relatives (P-value for interaction 0.02). The per allele OR associated with this variant was significantly higher than 1 (2.37; 95% C.I. = 1.01-5.57).

Conclusions

We suggest that genetic variation within the chromosome 4q27 locus might be associated with prostate cancer susceptibility in men with a family history of the disease. Furthermore, our study alludes to a potential role of unknown protein KIAA1109 in conferring this risk.

Chronic bacterial inflammation induces prostatic intraepithelial neoplasia in mouse prostate

Background:

Although the aetiology of prostate cancer remains unknown, we hypothesised that chronic bacterial insult has a major role in prostate carcinogenesis.

Methods:

Male C3H/HeOuJ mice, infected with phosphate-buffered saline or Escherichia coli bacteria, were killed at 5 days, or at 12 or 26 weeks. Harvested prostate tissues were evaluated for inflammatory responses and immunostained for neoplastic transformation markers.

Results:

All infected mice developed bacterial prostatitis. Control mice had no prostate infections or inflammation. Mice infected for 5 days showed foci of acute inflammation with infiltrating neutrophils and epithelial necrotic debris in the prostatic glandular lumen. All mice infected for 12 weeks had evidence of chronic inflammation with dense inflammatory infiltrates in the stroma. The prostatic epithelium showed varying degrees of atypical hyperplasia with increased epithelial cell layers and cytological atypia. At 26 weeks, the dysplastic changes were more pronounced and mimicked a prostatic intraepithelial neoplasia and high-grade dysplasia. Prostatic glands exhibiting reactive dysplasia had a stronger staining for oxidative DNA damage, increased epithelial cell proliferation, and a decrease in androgen receptor, GSTP1, p27^Kip1, and PTEN expression, when compared with control prostate glands.

Conclusion:

These data demonstrate that chronic inflammation induces focal prostatic glandular atypia and suggest a potential linkage between inflammation and prostatic neoplasia.

Birth characteristics and risk of prostate cancer: the contribution of genetic factors

BACKGROUND

Prostate cancer has a strong hereditary component, but it has been proposed that hormonal influences in utero may contribute to offspring risk. We investigated the associations between birth characteristics and the risk of prostate cancer in twins, and whether possible associations could be confounded by familial factors, such as shared environment and common genes.

METHODS

All like-sexed male twins in the Swedish Twin Registry, born from 1926 to 1958 and alive in 1973, were eligible. Data were obtained from birth records, and 11,420 male twins with reliable birth weight data were included in the final study population. Hazard ratios with 95% confidence intervals (CI) from Cox regression models were used to estimate associations between birth characteristics and risk of prostate cancer. Paired analysis was done to account for potential confounding by familial factors.

RESULTS

Compared with twins with a birth weight of 2,500 to 2,999 g, the hazard ratio (95% CI) for twins with a higher birth weight (>or=3,000 g) corresponded to 1.22 (0.94-1.57). In analyses within twin pairs, in which both twins had a birth weight of >or=2,500 g, a 500 g increase in birth weight was associated with an increased risk of prostate cancer within dizygotic twin pairs (odds ratio, 1.41; 95% CI, 1.02-1.57), but not within monozygotic twin pairs (odds ratio, 1.06; 95% CI, 0.61-1.84).

CONCLUSIONS

High birth weight is associated with an increased risk of prostate cancer. The difference in risk within dizygotic and monozygotic twin pairs may be due to genetic factors playing an important role in this association.

C-reactive protein haplotype is associated with high PSA as a marker of metastatic prostate cancer but not with overall cancer risk

Growing evidence points to a role for inflammation in prostate carcinogenesis. The significance of C-reactive protein (CRP), an inflammatory and innate immunity molecule, has not been evaluated thoroughly in prostate cancer (PC). In this study of 739 Finnish patients with PC and 760 healthy men, we evaluated the associations of CRP genotypes and haplotypes with total PC risk and PC progression, using prostate-specific antigen (PSA) as a marker of metastatic disease. Although the haplotype frequencies were similar in patients and controls, an association between haplotype ACCCA and patients' PSA levels was found. The carriers more often had a high PSA than non-carriers (P=0.0002) and the SNP rs2794521 A-allele and rs1800947 C-allele carriers had a higher PSA than non-carriers (P=0.009 and P=0.0004, respectively). A trend for a younger age at diagnosis was found among the carriers of ACCCA (P=0.07) and the rs1800947 C-allele (P=0.06), as well as a trend for the latter to have more likely metastases (P=0.06), but not after Bonferroni correction (α=0.00208). This is the first study to suggest association between PSA and CRP variants in PC and, therefore, further studies are warranted. CRP alleles previously found to protect against increased CRP levels are now suggested to be associated with metastatic PC, indicated by elevated PSA.

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.

Macrophage inhibitory cytokine-1: possible bridge molecule of inflammation and prostate cancer

There is emerging evidence that inflammation may lead to prostate cancer development. Although inflammation is an essential response to injury or infection, chronic inflammation is harmful and causes tissue damage. Increasing evidence suggests that inflammation leads to the development of epithelial cancers; however, studies on inflammation-targeted genes that might contribute to the development of cancer are at the beginning stage. Here, we describe macrophage inhibitory cytokine-1, which provides a potential link between inflammation and prostate cancer. Understanding the regulation of macrophage inhibitory cytokine-1 in response to inflammation may have potential for novel therapeutic strategies.

Inflammation and prostate cancer

Prostate cancer remains a major health concern for the male population throughout the Western world. It is today widely accepted that inflammation has a role in many human cancers. In fact, inflammation is thought to incite carcinogenesis by causing cell and genome damage, promoting cellular turnover and creating a tissue microenvironment that can enhance cell replication, angiogenesis and tissue repair. Accordingly, there is a body of literature suggesting a link between chronic inflammation and prostate cancer, in which prostate inflammation may contribute to the promotion of prostate cancer development. On the other hand, high levels of endogenous gonadal steroids are considered as risk factors for prostate cancer. Interestingly, it is clear that elevation of estrogens in the presence of testosterone results in a prostate-specific inflammatory response. Thus, it is possible that early inflammatory events stimulated by sex hormones serve as a prerequisite for the onset of prostate cancer.

Association of chromosomal locus 8q24 and risk of prostate cancer: a hospital-based study of German patients treated with brachytherapy

BACKGROUND

Genetic susceptibility contributes to the risk of prostate cancer but the underlying genes are largely unknown. Polymorphic loci on chromosome 8q24 have emerged as possible risk factors for breast and prostate cancer from genome-wide association studies.

OBJECTIVE

We aimed to define the risks associated with two single nucleotide polymorphisms, rs1447295 and rs13281615, in a hospital-based series of prostate cancer patients treated with brachytherapy.

MATERIAL AND METHODS

We analyzed genomic DNA samples of 488 prostate cancer cases undergoing brachytherapy at Hannover Medical School, and of 462 male controls from the same location. Genotyping was performed using 5'-exonuclease allelic discrimination assays, and results were evaluated with chi(2) tests and logistic regression analyses.

RESULTS

We investigated whether rs1447295 and rs13281615 are associated with disease risk in a hospital-based prostate cancer case-control series from Northern Germany. The rare allele of rs1447295 was observed at higher frequency among cases than among hospital-based controls (13.9% vs. 10.2%, P = 0.01), and there was a dose-dependent trend towards a higher prevalence of heterozygous and homozygous carriers among the prostate cancer patients (per allele OR 1.42, 95% CI 1.07; 1.87, P = 0.02). By contrast, the rare allele of rs13281615 did not predispose to prostate cancer (per allele OR 0.84, 95% CI 0.70; 1.00, P = 0.05). The distribution of combined 8q24 genotypes was significantly different between cases and controls (P = 0.01).

CONCLUSION

Our results corroborate previous reports of 8q24 as a prostate cancer susceptibility locus and provide evidence for rs1447295 as a potentially important genetic marker. Further studies are required to confirm whether the adjacent breast cancer-associated variant rs13281615 may be inversely associated with prostate cancer risk.

Genetic susceptibility to cancer: the role of polymorphisms in candidate genes

CONTEXT

Continuing advances in genotyping technologies and the inclusion of DNA collection in observational studies have resulted in an increasing number of genetic association studies.

OBJECTIVE

To evaluate the overall progress and contribution of candidate gene association studies to current understanding of the genetic susceptibility to cancer.

DATA SOURCES

We systematically examined the results of meta-analyses and pooled analyses for genetic polymorphisms and cancer risk published through March 2008.

STUDY SELECTION

We identified 161 meta-analyses and pooled analyses, encompassing 18 cancer sites and 99 genes. Analyses had to meet the following criteria: include at least 500 cases, have cancer risk as outcome, not be focused on HLA antigen genetic markers, and be published in English.

DATA EXTRACTION

Information on cancer site, gene name, variant, point estimate and 95% confidence interval (CI), allelic frequency, number of studies and cases, tests of study heterogeneity, and publication bias were extracted by 1 investigator and reviewed by other investigators.

RESULTS

These 161 analyses evaluated 344 gene-variant cancer associations and included on average 7.3 studies and 3551 cases (range, 508-19 729 cases) per investigated association. The summary odds ratio (OR) for 98 (28%) statistically significant associations (P value <.05) were further evaluated by estimating the false-positive report probability (FPRP) at a given prior probability and statistical power. At a prior probability level of 0.001 and statistical power to detect an OR of 1.5, 13 gene-variant cancer associations remained noteworthy (FPRP <0.2). Assuming a very low prior probability of 0.000001, similar to a probability assumed for a randomly selected single-nucleotide polymorphism in a genome-wide association study, and statistical power to detect an OR of 1.5, 4 associations were considered noteworthy as denoted by an FPRP value <0.2: GSTM1 null and bladder cancer (OR, 1.5; 95% CI, 1.3-1.6; P = 1.9 x 10(-14)), NAT2 slow acetylator and bladder cancer (OR, 1.46; 95% CI, 1.26-1.68; P = 2.5 x 10(-7)), MTHFR C677T and gastric cancer (OR, 1.52; 95% CI, 1.31-1.77; P = 4.9 x 10(-8)), and GSTM1 null and acute leukemia (OR, 1.20; 95% CI, 1.14-1.25; P = 8.6 x 10(-15)). When the OR used to determine statistical power was lowered to 1.2, 2 of the 4 noteworthy associations remained so: GSTM1 null with bladder cancer and acute leukemia.

CONCLUSION

In this review of candidate gene association studies, nearly one-third of gene-variant cancer associations were statistically significant, with variants in genes encoding for metabolizing enzymes among the most consistent and highly significant associations.

Genetic polymorphisms of human cytosol glutathione S-transferases and prostate cancer

Glutathione S-transferases (GSTs) are involved in the metabolism of a wide range of carcinogenic chemicals. In humans, cytosol GSTs are divided into eight classes: alpha (GSTA), mu (GSTM), pi (GSTP), theta (GSTT), tau (GSTZ), sigma (GSTS), omicron (GSTO) and kappa (GSTK). The allelic polymorphism of these enzymes is associated with variations in enzyme activity; hence, it may affect the concentration of activated carcinogenic chemicals in the body. In addition to the metabolism of chemical carcinogens, GSTs metabolize steroid hormones, compounds in the diet and other agents potentially involved in prostate carcinogenesis. Three genetic polymorphisms of GSTs, GSTM1*0 (null), GSTT1*0 (null) and GSTP1 A313G, have been well documented. No consistent associations between GSTM1, GSTT1 or GSTP1 genotypes and prostate cancer have been observed. Recent meta-analysis reports show that these polymorphisms of GSTM1, GSTT1 and GSTP1 are unlikely to be major determinants of susceptibility to prostate cancer.