Sexual behavior, sexually transmitted diseases and prostatitis: the risk of prostate cancer in black men

Prostate cancer and chronic prostatitis

Prostate cancer and chronic prostatitis are prevalent disorders in men. The cause of prostate cancer and chronic prostatitis is multifocal and diverse. Both disorders exhibit characteristic elevation of serum prostate-specific antigen, currently the primary screening test for prostate cancer. Prostate inflammation, regardless of cause, is the histopathologic hallmark of chronic prostatitis. In general, inflammation is associated with multiple cancers, and prostate inflammation, in particular, is a suggested factor in the development and progression of prostate cancer. This review addresses the link between chronic prostatitis and prostate cancer, especially as it relates to clinical practice.

Prevalence of and risk factors for prostatitis in African American men: the Flint Men's Health Study

INTRODUCTION

Prostatitis is a common, yet ill-defined condition without clear diagnostic criteria and treatment strategies. Previous studies examining the prevalence and correlates of prostatitis are limited in their inclusion of primarily white populations. The objective of the current study was to identify prevalence of and risk factors for prostatitis in a population-based sample of African-American men.

METHODS

In 1996, a probability sample of 703 African-American men, aged 40-79, residing in Genesee County, Michigan without a prior history of prostate cancer/surgery provided responses to a structured interview-administered questionnaire which elicited information regarding sociodemographics, current stress and health ratings, and past medical history, including history of physician diagnosed prostatitis, BPH and sexually transmitted diseases. Logistic regression was used to identify predictors of prostatitis after adjustment for age.

RESULTS

Forty-seven (6.7%) of the 703 men reported a history of prostatitis. Increased frequency of sexual activity and physical activity were significantly associated with decreased odds of disease. Moderate to severe lower urinary tract symptoms (LUTS) and a history of BPH were significantly associated with prostatitis after adjustment for age.

CONCLUSION

After adjustment for age, LUTS severity and history of BPH were associated with increased odds of prostatitis. BMI, physical activity and sexual frequency were associated with decreased odds of prostatitis. Finally, poor emotional and physical health, high perceived stress and low social support were associated with an increased risk of prostatitis history. Importantly, these findings suggest that the primary risk factors for this condition are largely modifiable and highlight potential targets for future prevention.

Induction of proinflammatory response in prostate cancer epithelial cells by activated macrophages

Emerging evidence indicates that chronic inflammation plays an important role in prostate carcinogenesis. Yet to date the precise molecular and cellular mechanisms linking inflammation to carcinogenesis remains unclear. The purpose of this study was to determine the local contribution of prostate epithelial cells to the inflammatory process. We characterized the inflammatory response elicited directly by prostate epithelial cells using an in vitro culture system in which androgen-dependent LNCaP prostate cancer epithelial cells were exposed to conditioned media from LPS-activated THP-1 macrophages. Upon exposure to activated macrophage conditioned media, LNCaP cells elicited a local proinflammatory response, as evidenced by NFkappaB activation, and the production of proinflammatory cytokines TNFalpha, IL-1beta, and IL-6. Furthermore, we observed a significant upregulation of the adhesion molecule VCAM-1 and nuclear estrogen receptor alpha (ERalpha) two biomarkers that correlate with tumor immune evasion and tumor progression. Our results suggest that prostate epithelial cells may play a significant role in sustaining and amplifying the inflammation process through NFkappaB activation and local production of proinflammatory cytokines that results in the recruitment and activation of additional immune cells in the prostate. At the same time, increased expression of VCAM-1 and ERalpha in prostate epithelial cells upon exposure to inflammatory conditions highlights the potential link between chronic inflammation and its involvement in promoting prostate cancer carcinogenesis.

Inflammation, infection, and prostate cancer

PURPOSE OF REVIEW

Recent evidence suggesting that inflammation and infection play a role in the etiology of prostate cancer, and the discovery of a novel virus in men with a genetic susceptibility to prostate cancer is reviewed.

RECENT FINDINGS

Almost 20% of visceral cancers worldwide have proven infectious causes. There is substantial histologic, molecular genetic, and epidemiologic evidence that infections and inflammation are also important in the pathogenesis of prostate cancer. The R462Q allelic variant in RNASEL, an antiviral gene important in the innate immune response to viral infections, increases susceptibility to prostate cancer while resulting in vitro in deficient antiviral defenses, suggesting that prostate cancer could be caused by a virus. The study of R462Q carriers led to the discovery and biologic characterization of a novel retrovirus, xenotropic murine leukemia-related virus, isolated and cloned from prostate tissue of affected men. Biologic studies of this virus show that it is sensitive to inhibition by interferon and its downstream mediator, RNaseL, and that its DNA has integrated into the DNA of some men with prostate cancer.

SUMMARY

Inflammation triggered by infection and other causes underlies the development of prostate cancer, and xenotropic murine leukemia-related virus is a candidate etiologic agent. Ongoing studies seek to define its oncogenic potential and pathogenesis.

Toll-like receptor-9 expression is inversely correlated with estrogen receptor status in breast cancer

Toll-like receptor 9 (TLR9) recognizes microbial and vertebrate DNA. We previously demonstrated TLR9 expression in human breast cancer cell lines and showed that TLR9 ligands stimulate their in vitro invasion. The aim of this study was to characterize TLR9 expression in clinical breast cancer specimens. Immunohistochemical staining intensity was compared with known baseline prognostic factors and distant metastasis-free survival. TLR9 expression was detected in 98% of the tumors studied (n = 141). The mean TLR9 staining intensity was higher in ER- than in the highly ER+ breast cancers (p = 0.039). High-grade tumors had significantly increased TLR9 expression (p = 0.027) compared with lower-grade tumors. The highest TLR9 expression was detected in the mucinous and the lowest in the tubular breast cancers (p = 0.034). Distant metastasis-free survival was higher in the lower TLR9-expressing half of the cohort than in the higher TLR9-expressing group (p = 0.118). TLR9 expression did not correlate with menopausal, PgR or Her2 status, patient age, tumor proliferative or invasive characteristics.

Proliferative inflammatory atrophy: a background lesion of prostate cancer?

Proliferative inflammatory atrophy (PIA) belongs to the atrophic lesions that frequently occur in the prostate. The location of PIA in the periphery of the gland near to prostate carcinoma or even showing direct transition to malignant or pre-malignant epithelia suggested a connection between PIA and prostate cancer. Further findings in PIA, such as imbalance between proliferation and apoptosis and detection of molecular-biological abnormalities specific for oxidative stress or malignancy, supported this hypothesis. Recently, epidemiological studies including large cohorts of patients have been undertaken in order to investigate the causal connection between PIA and prostate carcinoma. The current understanding of PIA allows us to consider it as a benign lesion with certain genetic instability which can degenerate into prostate intraepithelial neoplasia or carcinoma, provided that the balance between anti-carcinogens and carcinogens is perturbed. To evaluate the role of PIA as a precursor lesion of prostate cancer, further examinations of genetic or epigenetic aberrations are required.

Direct visualization of Propionibacterium acnes in prostate tissue by multicolor fluorescent in situ hybridization assay

Prostate tissues from patients with prostate cancer and benign prostatic hyperplasia (BPH) frequently contain histological inflammation, and a proportion of these patients show evidence of Propionibacterium acnes infection in the prostate gland. We developed a multicolor fluorescent in situ hybridization (FISH) assay targeting P. acnes 23S rRNA along with a 14-kb region of the P. acnes genome. This assay was used to analyze prostate tissues from patients with prostate cancer and BPH. P. acnes infection of the prostate gland was demonstrated in prostatic tissue in 5 of 10 randomly selected prostate cancer patients. FISH analysis and confocal laser microscopy imaging revealed intracellular localization and stromal biofilm-like aggregates as common forms of P. acnes infection in prostate tissues from both prostate cancer and BPH patients. A sequential analysis of prostate tissue from individual patients suggested that P. acnes can persist for up to 6 years in the prostate gland. These results indicate that P. acnes can establish a persistent infection in the prostate gland. Further study is needed to clarify the link between this bacterium and prostatic inflammation which may contribute to the development of BPH and prostate cancer.

Toll like receptor-9 agonists stimulate prostate cancer invasion in vitro

BACKGROUND

Toll-like receptor 9 (TLR9) recognizes microbial DNA. In addition to immune cells, TLR9 expression has been detected in various cancer cells. We showed recently that TLR9 agonistic CpG-oligonucleotides (CpG-ODNs) induce matrix metalloproteinase-13 (MMP-13)-mediated invasion in TLR9-expressing (TLR9(+)) breast cancer cells. We investigated here TLR9 expression and function in human prostate cancer (CaP) cells.

METHODS

TLR9 expression was detected with Western blotting and immunohistochemistry. Invasion was studied with Matrigel-assays. MMP-13 was assayed with ELISA.

RESULTS

Human CaP cell lines and clinical samples exhibit various levels of TLR9 expression. Treatment of TLR9(+), but not TLR9(-) CaP cells with CpG-ODNs or bacterial DNA increased their invasion, which was inhibited with chloroquine. CpG-ODN-treatment also increased MMP-13 activity and neutralizing anti-MMP-13 antibody prevented CpG-ODN-induced invasion in TLR9(+) CaP cells. Estradiol up-regulated TLR9 expression in LnCaP cells.

CONCLUSIONS

TLR9-mediated invasion may represent a novel mechanism through which infections promote prostate cancer.

Inflammation in prostate carcinogenesis

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