Prostate cancer immunology - an update for Urologists

Nitric oxide donors for prostate and bladder cancers: Current state and challenges

Nitric oxide (NO) is an endogenous molecule that plays pivotal physiological and pathophysiological roles, particularly in cancer biology. Generally, low concentrations of NO (pico- to nanomolar range) lead to tumor promotion. In contrast, high NO concentrations (micromolar range) have pro-apoptotic functions, leading to tumor suppression, and in this case, NO is involved in immune surveillance. Under oxidative stress, inducible NO synthase (iNOS) produces high NO concentrations for antineoplastic activities. Prostate and bladder cancers are the most commonly detected cancers in men, and are related to cancer death in males. This review summarizes the state of the art of NO/NO donors in combating prostate and bladder cancers, highlighting the importance of NO donors in cancer treatment, and the limitations and challenges to be overcome. In addition, the combination of NO donors with classical therapies (radio- or chemotherapy) in the treatment of prostate and bladder cancers is also presented and discussed. The combination of NO donors with conventional anticancer drugs is reported to inhibit tumor growth, since NO is able to sensitize tumor cells, enhancing the efficacy of the traditional drugs. Although important progress has been made, more studies are still necessary to definitely translate the administration of NO donors to clinical sets. The purpose of this review is to inspire new avenues in this topic.

Immunogenetics of prostate cancer and benign hyperplasia--the potential use of an HLA-G variant as a tag SNP for prostate cancer risk

Human leukocyte antigen G (HLA-G) is an immunomodulatory molecule with important roles both physiologically as well as an escape mechanism of cancer cells. In this study, we evaluated the impact of eight polymorphisms at the 3' untranslated region (3'UTR) of the HLA-G gene in the development of prostate cancer (PCa) and benign prostatic hyperplasia (BPH). A total of 468 DNA samples of Brazilian men predominantly Euro-descendant with PCa (N = 187), BPH (N = 152) and healthy control individuals (N = 129) were evaluated. The HLA-G 3'UTR region was amplified by polymerase chain reaction (PCR), sequenced and genotyped to identify the 14 bp insertion/deletion (rs371194629), +3003T/C (rs1707), +3010C/G (rs1710), +3027A/C (rs17179101), +3035C/T (rs17179108), +3142G/C (rs1063320), +3187A/G (rs9380142) and +3196C/G (rs1610696) polymorphisms. Regression logistic and chi-square tests were performed to verify the influence of single nucleotide polymorphisms (SNPs) in PCa and/or BPH susceptibility, as well as in PCa progression (clinicopathological status). Our data showed the UTR-4 haplotype as a risk factor to PCa in comparison with control [odds ratio (OR) 2.35, 95% confidence interval (CI) 1.39-3.96, P adjusted = 0.003) and BPH groups (OR 1.82, 95% CI 1.15-2.86, P adjusted = 0.030). Further, the 'non-14bp Ins_ + 3142G_+3187A' haplotype (OR 1.56, 95% CI 1.10-2.20, P adjusted = 0.036), the +3003CT genotype (OR 4.44, 95% CI 1.33-4.50, P adjusted = 0.032) and the +3003C allele (OR 2.33, 95% CI 1.38-3.92, P adjusted = 0.016) also conferred susceptibility to PCa. Our data suggest an important influence of HLA-G 3'UTR polymorphisms in PCa susceptibility and support the use of the +3003 variant as a tag SNP for PCa risk.

Human Prostate Cancer Hallmarks Map

Human prostate cancer is a complex heterogeneous disease that mainly affects elder male population of the western world with a high rate of mortality. Acquisitions of diverse sets of hallmark capabilities along with an aberrant functioning of androgen receptor signaling are the central driving forces behind prostatic tumorigenesis and its transition into metastatic castration resistant disease. These hallmark capabilities arise due to an intense orchestration of several crucial factors, including deregulation of vital cell physiological processes, inactivation of tumor suppressive activity and disruption of prostate gland specific cellular homeostasis. The molecular complexity and redundancy of oncoproteins signaling in prostate cancer demands for concurrent inhibition of multiple hallmark associated pathways. By an extensive manual curation of the published biomedical literature, we have developed Human Prostate Cancer Hallmarks Map (HPCHM), an onco-functional atlas of human prostate cancer associated signaling and events. It explores molecular architecture of prostate cancer signaling at various levels, namely key protein components, molecular connectivity map, oncogenic signaling pathway map, pathway based functional connectivity map etc. Here, we briefly represent the systems level understanding of the molecular mechanisms associated with prostate tumorigenesis by considering each and individual molecular and cell biological events of this disease process.

Dietary methionine restriction inhibits prostatic intraepithelial neoplasia in TRAMP mice

BACKGROUND

Prostate cancer (PCa) is a major aging-related disease for which little progress has been made in developing preventive strategies. Over the past several years, methionine restriction (MR), the feeding of a diet low in methionine (Met), has been identified as an intervention which significantly extends lifespan and reduces the onset of chronic diseases, including cancer, in laboratory animals. We, therefore, hypothesized that MR may be an effective strategy for inhibiting PCa.

METHODS

Control (0.86% Met) or MR (0.12% Met) diets were fed to 5-week old TRansgenic Adenocarcinoma of the Mouse Prostate (TRAMP) mice, a well-characterized model for PCa. The mice were sacrificed at 16 weeks of age and prostate and other tissues were harvested for histological and biochemical analyses.

RESULTS

As previously reported, MR was associated with a decrease in body weight which was not associated with lowered food intake. MR led to significant reductions in the development of Prostatic Intraepithelial Neoplasia (PIN) lesions, specifically in the anterior and dorsal lobes of the prostate where the incidence of high-grade PIN was reduced by ∼50% (P < 0.02). The reduction in PIN severity was associated with 46-64% reductions in cell proliferation rates (P < 0.02) and plasma IGF-1 levels (P < 0.0001), which might, in part, explain the effects on carcinogenesis. Additionally, no adverse consequences of MR on immune function were observed in the TRAMP mice.

CONCLUSIONS

Overall, these findings indicate that MR is associated with a reduction in prostate cancer development in the TRAMP model and supports the continued development of MR as a potential PCa prevention strategy.

Infiltration of CD8+ lymphocytes is an independent prognostic factor of biochemical failure-free survival in prostate cancer

BACKGROUNDS

The adaptive immune system can potentially have dual roles in cancer development and progression by contributing to or suppressing tumor progression and metastasis. The aim of this study was to evaluate the prognostic impact of adaptive immune cells residing in different tumor compartments in prostate cancer.

METHODS

Tissue microarrays from 535 patients were constructed from viable and representative tumor epithelial and stromal areas of primary PC tumors, as well as from normal epithelial and stromal areas. Immunohistochemistry was used to evaluate the density of CD3+, CD4+, CD8+, and CD20+ lymphocytes in both tumor epithelial and tumor stromal areas.

RESULTS

In univariate analysis, a high density of CD3+ (P = 0.037) and CD8+ lymphocytes (P = 0.010) in tumor epithelial areas was associated with significantly shorter biochemical failure-free survival. When analyzing both tumor epithelial and stromal tissue compartments as one entity, similar relationships were observed for CD3+ (P = 0.046), CD4+ (P = 0.026), and CD8+ (P = 0.003) lymphocytes. In multivariate analysis, high densities of CD8+ lymphocytes limited to tumor epithelial areas (HR = 1.45, P = 0.032), as well as in the total tumor tissue (HR = 1.57, P = 0.007), were independent negative prognostic factors for biochemical failure-free survival.

CONCLUSIONS

A high density of CD8+ lymphocytes, especially in tumor epithelial areas, is an independent negative prognostic factor for biochemical failure-free survival.

The biology and natural history of prostate cancer: a short introduction

This chapter aims to serve as a quick glance outlining an overall picture of mainstream thoughts, and to serve as a point of departure for more thorough discussions. The introduction of PSA testing has immensely complicated research in prostate cancer epidemiology and biology and added new clinical and biological domains. As for many cancers, age and ethnic origin are the strongest known risk factors. While migrant studies imply that environment and/or personal life style is important, epidemiological studies have failed to establish any strong leads. Despite the known androgen dependence of prostate cancer, there is little to support that circulating levels of androgens, estrogens or 5-alpha-reductase are associated with risk of developing the disease. However, a consistent finding is a positive association with levels of Insulin-like Growth Factor-1 (IGF-1). Prostate cancer is one of the cancers most strongly related to inherited susceptibility, even when taking into account that family history of prostate cancer triggers PSA testing among relatives. A number of somatic genetic alterations (amplifications, deletions, point mutations, translocations) are associated with prostate cancer risk. Findings for alterations in FASN, HPN, AMACR and MYC have been fairly consistent. Recent research shows that the notion of "hormone-independent prostate cancer" has to be revised: most prostate cancers remain dependent on androgen receptor signalling also after progression despite traditional androgen deprivation therapy. Traditional markers of stage and type of disease still play a major role for prognostication and treatment decisions. Prostate cancer is one of the few cancers where patients have been recommended watchful waiting or active surveillance. This provides opportunities for studies of natural history of the disease. The understanding of prostate cancer aetiology and natural history has progressed slowly. However, the current situation is positively challenging and opens up possibilities for fruitful research.

Glasgow prognostic score as a prognostic factor in metastatic castration-resistant prostate cancer treated with docetaxel-based chemotherapy

BACKGROUND

The modified Glasgow Prognostic Score (mGPS), derived from C-reactive protein (CRP) and albumin levels, and the neutrophil-lymphocyte ratio (NLR) have demonstrated prognostic significance in a number of malignancies.

PATIENTS AND METHODS

Baseline mGPS and NLR were calculated in a prospective cohort of chemotherapy-naive patients with metastatic castration-resistant prostate cancer (mCRPC) (AT-101-CS-205 trial) who received docetaxel and prednisone ± AT101. Cox proportional hazards regression models estimated their effects on overall survival (OS).

RESULTS

Of 220 eligible patients, mGPS and neutrophil and lymphocyte counts were available for 184, 193, and 112 patients, respectively. Albumin (hazard ratio [HR], 0.28; 95% confidence interval [CI]: 0.14-0.56; P < .001) and CRP (HR, 1.22; 95% CI, 1.00-1.48; P = .048) were independently prognostic for OS. An association between mGPS and OS was found (HR, 1.87; 95% CI, 1.35-2.59; P < .001; median survival, 23.5 months at mGPS 0 vs. 9.8 months at mGPS 2). mGPS was significant after controlling for 3 previously published nomograms or NLR (P ≤ .001). NLR was not prognostic for OS (HR, 0.98; P = .91), and no association between mGPS and toxicity was noted.

CONCLUSION

Our results demonstrate the prognostic role of the mGPS in mCRPC over variables previously identified. mGPS is inexpensive, easily measured, and could be incorporated into routine clinical testing if our results are confirmed in a subsequent validation study. The utility of the NLR in mCRPC remains uncertain despite evidence in other malignancies.

Regulation of prostate cancer immunity-related genes in PC3 prostate cancer cells by ETS-1

Prostate cancer (PCa) is one of the most prevalent forms of cancer affecting males worldwide, and knowledge of the immune defenses involved in PCa remains incomplete. Since the identification of immunity-related genes may have enormous implications for the understanding of PCa immunology, we recently reported the identification of immunity-related genes in PCa tissues and found potential binding sites for the ETS family prototype, ETS-1, in the majority of genes identified. Therefore, as a continuation of our previous study, we investigated whether ETS-1 regulates these genes in an in vitro PCa cell line model, PC3 cells. We specifically blocked ETS-1 in PC3 cells by transfection with an ETS-1 inverse antisense expression vector or a mock control vector. We then assessed the effect of the blockade on the expression of the recently identified PCa immunity-related genes using a comprehensive oligo gene expression microarray analysis. The results showed that ETS-1 is involved in the activation or repression of the recently identified immunity-related genes in PCa. These findings provide insights into the regulation of immunity-related genes in PCa, and emphasize the importance of ETS-1 in prostate cancer immunology.

Nuclear morphometry, nucleomics and prostate cancer progression

Prostate cancer (PCa) results from a multistep process. This process includes initiation, which occurs through various aging events and multiple insults (such as chronic infection, inflammation and genetic instability through reactive oxygen species causing DNA double-strand breaks), followed by a multistep process of progression. These steps include several genetic and epigenetic alterations, as well as alterations to the chromatin structure, which occur in response to the carcinogenic stress-related events that sustain proliferative signaling. Events such as evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis are readily observed. In addition, in conjunction with these critical drivers of carcinogenesis, other factors related to the etiopathogenesis of PCa, involving energy metabolism and evasion of the immune surveillance system, appear to be involved. In addition, when cancer spread and metastasis occur, the 'tumor microenvironment' in the bone of PCa patients may provide a way to sustain dormancy or senescence and eventually establish a 'seed and soil' site where PCa proliferation and growth may occur over time. When PCa is initiated and progression ensues, significant alterations in nuclear size, shape and heterochromatin (DNA transcription) organization are found, and key nuclear transcriptional and structural proteins, as well as multiple nuclear bodies can lead to precancerous and malignant changes. These series of cellular and tissue-related malignancy-associated events can be quantified to assess disease progression and management.

Is XMRV a causal virus for prostate cancer?

The potential association between xenotropic murine leukaemia virus-related gammaretrovirus (XMRV) and prostate cancer (PCa) has been documented since 2006. It is important for furthering our understanding of the biological mechanisms of PCa to ascertain whether this association is causal. To summarize the available information on the epidemiological and laboratory findings of the association, we conducted a literature search of the PubMed electronic database (from March 2006 to February 2011) to identify relevant published studies that examined the association between XMRV and PCa. Although several studies showed the positive association between XMRV and PCa, more recent studies did not support this conclusion. The positive findings might be due to contamination of human samples. Further studies are needed to clarify this association.

Minireview: Alternative activation pathways for the androgen receptor in prostate cancer

Advanced prostate tumors, which are androgen dependent, are often initially treated in the clinic with hormone ablation therapy, either through surgical castration or administration of small-molecule antiandrogens. Most tumors respond favorably to these treatments, exhibiting regression of the tumor, amelioration of symptoms, and a decrease of prostate-specific antigen in patient sera. However, with time, the majority of tumors recur in a more aggressive, castration-resistant (CR) phenotype. Currently, no effective treatment exists for this stage of the cancer, and patients ultimately succumb to metastatic disease. The androgen receptor (AR), which is a member of the nuclear hormone receptor superfamily of proteins, is the transcription factor that is responsible for mediating the effects of androgens upon target tissues, and it has been demonstrated to play a central role in the development and progression of prostate cancer. Despite CR tumor cells being able to continue to grow after hormonal therapy in which testosterone and dihydrotestosterone are markedly reduced, they still require the expression and activity of the AR. The AR can become transactivated in this low-androgen environment through a number of different mechanisms, including amplification and mutation of the receptor, cross talk with other signaling pathways, and altered regulation by coregulatory proteins. This review will summarize the most current data regarding non-ligand-mediated activation of the AR in prostate cancer cells. Developing work in this field aims to more clearly elucidate the signals that drive AR activity independently of androgens in CR disease so that better therapeutic targets can be developed for patients with this stage of highly aggressive prostate carcinoma.