The role of inflammatory mediators in the development of prostatic hyperplasia and prostate cancer

Bmal1 Regulates Prostate Growth via Cell-Cycle Modulation

The circadian clock system exists in most organs and regulates diverse physiological processes, including growth. Here, we used a prostate-specific Bmal1-knockout mouse model (pBmal1 KO: PbsnCre+; Bmal1^fx/fx) and immortalized human prostate cells (RWPE-1 and WPMY-1) to elucidate the role of the peripheral prostate clock on prostate growth. Bmal1 KO resulted in significantly decreased ventral and dorsolateral lobes with less Ki-67-positive epithelial cells than the controls. Next, the cap analysis of gene expression revealed that genes associated with cell cycles were differentially expressed in the pBmal1 KO prostate. Cdkn1a (coding p21) was diurnally expressed in the control mouse prostate, a rhythm which was disturbed in pBmal1 KO. Meanwhile, the knockdown of BMAL1 in epithelial RWPE-1 and stromal WPMY-1 cell lines decreased proliferation. Furthermore, RWPE-1 BMAL1 knockdown increased G0/G1-phase cell numbers but reduced S-phase numbers. These findings indicate that core clock gene Bmal1 is involved in prostate growth via the modulation of the cell cycle and provide a rationale for further research to link the pathogenesis of benign prostatic hyperplasia or cancer with the circadian clock.

Anti-Proliferative Effects of Standardized Cornus officinalis on Benign Prostatic Epithelial Cells via the PCNA/E2F1-Dependent Cell Cycle Pathway

Cornus officinalis, widely used in traditional Chinese medicine, exhibits pharmacological effects against erectile dysfunction and pollakisuria, which are pathological symptoms of benign prostatic hyperplasia (BPH). Although traditional usage and a study on BPH have been reported, to our knowledge, no study has investigated the exact molecular mechanism(s) underlying the anti-proliferative effects of standardized C. officinalis on prostatic cells. We standardized C. officinalis 30% ethanol extract (COFE) and demonstrated the therapeutic effects of COFE on human BPH epithelial cells and testosterone-induced BPH in rats. In vitro studies using BPH-1 cells demonstrated an upregulation of BPH-related and E2F Transcription Factor 1(E2F1)-dependent cell cycle markers, whereas treatment with COFE clearly inhibited the proliferation of BPH epithelial cells and reduced the overexpression of G1 and S checkpoint genes. Additionally, COFE administration alleviated the androgen-dependent prostatic enlargement in a testosterone-induced BPH animal model. COFE exerted these anti-BPH effects by the inhibition of anti-apoptotic markers, suppression of PCNA expression, and regulation of E2F1/pRB-dependent cell cycle markers in rats with BPH. These results suggest that COFE exerts anti-proliferative effect by regulating PCNA/E2F1-dependent cell cycle signaling pathway both in vivo and in vitro. These findings reveal the therapeutic potential of COFE, which could be used as a substitute for BPH treatment.

The human microbiome and its link in prostate cancer risk and pathogenesis

There is growing evidence of the microbiome's role in human health and disease since the human microbiome project. The microbiome plays a vital role in influencing cancer risk and pathogenesis. Several studies indicate microbial pathogens to account for over 15-20% of all cancers. Furthermore, the interaction of the microbiota, especially the gut microbiota in influencing response to chemotherapy, immunotherapy, and radiotherapy remains an area of active research. Certain microbial species have been linked to the improved clinical outcome when on different cancer therapies. The recent discovery of the urinary microbiome has enabled the study to understand its connection to genitourinary malignancies, especially prostate cancer. Prostate cancer is the second most common cancer in males worldwide. Therefore research into understanding the factors and mechanisms associated with prostate cancer etiology, pathogenesis, and disease progression is of utmost importance. In this review, we explore the current literature concerning the link between the gut and urinary microbiome and prostate cancer risk and pathogenesis.

The FGF/FGFR system in the physiopathology of the prostate gland

Fibroblast growth factors (FGFs) are a family of proteins possessing paracrine, autocrine, or endocrine functions in a variety of biological processes, including embryonic development, angiogenesis, tissue homeostasis, wound repair, and cancer. Canonical FGFs bind and activate tyrosine kinase FGF receptors (FGFRs), triggering intracellular signaling cascades that mediate their biological activity. Experimental evidence indicates that FGFs play a complex role in the physiopathology of the prostate gland that ranges from essential functions during embryonic development to modulation of neoplastic transformation. The use of ligand- and receptor-deleted mouse models has highlighted the requirement for FGF signaling in the normal development of the prostate gland. In adult prostate, the maintenance of a functional FGF/FGFR signaling axis is critical for organ homeostasis and function, as its disruption leads to prostate hyperplasia and may contribute to cancer progression and metastatic dissemination. Dissection of the molecular landscape modulated by the FGF family will facilitate ongoing translational efforts directed toward prostate cancer therapy.

Protocatechuic acid ameliorates testosterone-induced benign prostatic hyperplasia through the regulation of inflammation and oxidative stress in castrated rats

Protocatechuic acid (PA) is a polyphenol-recognized for its efficacy as an antioxidant-possesses anticancer, anti-inflammatory, antioxidant properties. The efficacy of PA in the management of benign prostatic hyperplasia (BPH) has not been investigated. Forty-two castrated rats (n = 7) were treated as follows: control (corn oil), BPH only received testosterone propionate (TP) (TP 3 mg/kg intraperitoneally), BPH + PA (TP 3 mg/kg + PA 40 mg/kg), BPH + finasteride (Fin) (TP 3 mg/kg + Fin 10 mg/kg), PA only (40 mg/kg: by gavage), and Fin only (10 mg/kg: by gavage) for 4 weeks. In BPH rats, there were significant (P < .05) increases in prostatic (250%) and organosomatic (280%) weights compared with controls. Cotreatment decreased prostatic weights by 19% (PA) and 21% (Fin). Markers of inflammation: myeloperoxidase activities increased in serum (148%) and prostate (70%), as well as nitric oxide levels serum (92%) and prostatic (95%). Proinflammatory cytokines interleukin-1β and tumor necrosis factor-α increased by 3.6- and 2.8-fold. Furthermore, prostatic malondialdehyde, superoxide dismutase, and serum total acid phosphatase increased by 97%, 25%, and 48%, respectively. Histology revealed poor architecture and severe proliferation of the prostate in BPH rats. Inflammation and oxidative stress markers, as well as the histological alteration in BPH rats, was attenuated (P < .05) upon cotreatment with PA and comparable with Fin cotreatment. These results suggest that PA mitigates oxido-inflammatory responses and restored prostatic cytoarchitecture to levels comparable with control in rats induced with BPH.

The Expression of Transforming Growth Factor Beta-1 and Interleukin-6 on Human Prostate: Prostate Hyperplasia and Prostate Cancer

BACKGROUND

Prostate hyperplasia and prostate cancer are two of the most common pathological condition of the prostate to be found on male. Both of these diseases share common pathogenesis involving inflammation of prostatic tissues. Chronic inflammation will induce the release of cytokines, followed by cells injury and tissues damage. One of the cytokines that play a role in prostate pathology is IL-6. The inflammation will also induce the releases of anti-inflammatory cytokines such as TGFβ-1.

AIM

This study aims to analyse the expression of IL-6 and TGFβ-1, in prostate hyperplasia and prostate cancer.

MATERIAL AND METHODS

This is an observational study, using paraffin-embedded tissue samples of prostate hyperplasia and prostate cancer. Samples were obtained from the laboratory of Pathological Anatomy, Faculty of Medicine, Andalas University, Padang, Indonesia. Immunohistochemistry was performed to detect the cytokine expression, and a semiqunatitaves measurement according to Immunoreactive score (IRS) was performed for evaluation. For the TGFβ-1, the stromal expression was also analysed by measurement of the stromal stained area. The correlation of cytokine expression to Gleason index score was also analysed in prostate cancer.

RESULTS

The result showed that this study found that TGFβ-1 was detected both in the stromal component as well as epithelial. With the stromal being the dominant site of expression. The stromal TGFβ-1 expression was of significantly higher in prostate hyperplasia compares to prostate cancer (p < 0.05), while the epithelial expression of TGFβ-1 was not found to be significantly different. IL-6 was mostly expressed intracytoplasmic in epithelia. The IL-6 expression was significantly higher in prostate cancer compared to hyperplasia. However, there was no significant correlation to found between IL-6 expression to the Gleason Score among prostate cancers.

CONCLUSION

This study concluded that there were differences in expression of both TGFβ-1 and IL-6 between prostate hyperplasia and prostate cancer tissue by immunohistochemistry.

Association between HPV infection and prostate cancer in a Mexican population

The aim of this study was to evaluate the association between prostate cancer (PCa) and Human papillomavirus (HPV) infection in the Mexican population. We studied 356 paraffin-embedded tissues from unrelated Mexican men with PCa or benign prostatic hyperplasia (BPH), with the latter serving as control. HPV detection was performed by polymerase chain reaction (PCR) using universal primers, and viral genotypes were detected using sequencing or multiplex PCR. Light microscopy analyses enabled the identification of koilocytes in samples subsequently analyzed for HPV detection by in situ PCR and for p16-INK4A expression by immunohistochemistry. The results showed that high risk- (HR) HPVs were detected in 37/189 (19.6%) PCa specimens compared to 16/167 (9.6%) of BHP specimens (odds ratio 2.3; 95% CI= 1.2 to 4.3; p=0.01). These data suggest HR-HPV may play a role in PCa. HPV 52 and 58 were the most frequent genotypes (33 and 17%, respectively) detected in the population studied. Koilocytes were detected in all in situ PCR-HPV-positive samples, representing a pathognomonic feature of infection, and we observed the overexpression of p16-INK4A in HPV-positive samples compared to HPV-negative samples, indirectly suggesting the presence of HR-HPV E7 oncoprotein. These results suggest that HPV infection plays an important role in prostate cancer development.

Targeting Crosstalk between Nrf-2, NF-κB and Androgen Receptor Signaling in Prostate Cancer

Oxidative stress, inflammation and androgen receptor (AR) signaling play a pivotal role in the initiation, development and progression of prostate cancer (PCa). Numerous papers in the literature have documented the interconnection between oxidative stress and inflammation; and how antioxidants can combat the inflammation. It has been shown in the literature that both oxidative stress and inflammation regulate AR, the key receptor involved in the transition of PCa to castration resistant prostate cancer (CRPC). In this review, we discuss about the importance of targeting Nrf-2-antioxidant signaling, NF-κB inflammatory response and AR signaling in PCa. Finally, we discuss about the crosstalk between these three critical pathways as well as how the anti-inflammatory antioxidant phytochemicals like sulforaphane (SFN) and curcumin (CUR), which can also target AR, can be ideal candidates in the chemoprevention of PCa.

Inflammatory mediators in the development and progression of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is the most common urological disease in elderly men. Epidemiological data suggest a causal link between this condition and prostatic inflammation. The prostate is an immune-competent organ characterized by the presence of a complex immune system. Several stimuli, including infectious agents, urinary reflux, metabolic syndrome, the ageing process, and autoimmune response, have been described as triggers for the dysregulation of the prostatic immune system via different molecular pathways involving the development of inflammatory infiltrates. From a pathophysiological standpoint, subsequent tissue damage and chronic tissue healing could result in the development of BPH nodules.

Molecular alterations associated with prostate cancer

Introduction

The amount of information and knowledge about pathways and genetic alterations regarding prostate cancer, including the tools available for its study has been recently increasing. Additionally, a variety of molecular signaling pathways control cell proliferation, however, this incompletely understood process is disturbed in cancer cells.

Materials and methods

A literature review was made using the MEDLINE, Embase and LILACS databases searching for the following keywords: prostate neoplasms, prostate cancer, molecular medicine, genomics, pathways, and cell cycle.

Results

Different biological mechanisms have been associated with the development of prostate cancer, such as alterations in tumor suppressor genes, oncogenes (TP53, RB1, among others) and CDKIs; DNA methylation; chromosomal alterations and rearrangements; changes in PTEN and PI3K / mTOR; global defects in apoptosis; alterations in the androgen receptor (AR); and epigenetic mechanisms.

Conclusions

Good clinical practice and a practical approach have to be based on basic knowledge, thus, in this article, the main genetic alterations, mutations and pathways involved in prostate cancer development were reviewed.

Intracrine prostaglandin E2 pro-tumoral actions in prostate epithelial cells originate from non-canonical pathways

Prostaglandin E₂ (PGE₂ ) increases cell proliferation and stimulates migratory and angiogenic abilities in prostate cancer cells. However, the effects of PGE₂ on non-transformed prostate epithelial cells are unknown, despite the fact that PGE₂ overproduction has been found in benign hyperplastic prostates. In the present work we studied the effects of PGE₂ in immortalized, non-malignant prostate epithelial RWPE-1 cells and found that PGE₂ increased cell proliferation, cell migration, and production of vascular endothelial growth factor-A, and activated in vitro angiogenesis. These actions involved a non-canonic intracrine mechanism in which the actual effector was intracellular PGE₂ (iPGE₂ ) instead of extracellular PGE₂ : inhibition of the prostaglandin uptake transporter (PGT) or antagonism of EP receptors prevented the effects of PGE₂ , which indicated that PGE₂ activity depended on its carrier-mediated translocation from the outside to the inside of cells and that EP receptors located intracellularly (iEP) mediated the effects of PGE₂ . iPGE₂ acted through transactivation of epidermal growth factor-receptor (EGFR) by iEP, leading to increased expression and activity of hypoxia-inducible factor-1α (HIF-1α). Interestingly, iPGE₂ also mediates the effects of PGE₂ on prostate cancer PC3 cells through the axis iPGE₂ -iEP receptors-EGFR-HIF-1α. Thus, this axis might be responsible for the growth-stimulating effects of PGE₂ on prostate epithelial cells, thereby contributing to prostate proliferative diseases associated with chronic inflammation. Since this PGT-dependent non-canonic intracrine mechanism of PGE₂ action operates in both benign and malignant prostate epithelial cells, PGT inhibitors should be tested as a novel therapeutic modality to treat prostate proliferative disease.

Intraurethral injection with LPS: an effective experimental model of prostatic inflammation

OBJECTIVE

Chronic inflammation has been recognized as having a prominent role pathogenesis of benign prostatic hyperplasia (BPH) and cancer. It is believed that chronic inflammation induces prostatic fibromuscular growth. This correlation has been clearly illustrated by both in vivo and in vitro studies; however, current experimental models of BPH require complex surgery or hormonal treatment. Therefore, the aim of the present study was to propose a new murine model of BPH/prostatitis induced by intraurethral injection of LPS.

METHODS

Male Swiss and C57Bl/6 mice were then sacrificed 3, 7, 10, and 14 days after intraurethral injection of LPS. The prostates were quickly dissected and fixed for morphological and immunohistochemical analyses.

RESULTS

The results showed that LPS played an important role in the cell proliferation of the prostate. Histological and ultrastructural analysis showed epithelial hyperplasia, clear stromal cells, little inflammatory infiltration, and heavy bleeding. Treatment with LPS also promoted the increase of growth factor (FGF-7 and TGF-β), α-actin, and proinflammatory cytokines (IL-1, IL-6, IL-17), both in the stroma and epithelium.

CONCLUSION

According to the present findings, it can be concluded that the intraurethral administration of LPS promotes tissue remodeling, as well as stimulating the pattern of pro-inflammatory cytokines, and therefore, constitutes an effective experimental model of BPH/inflammation.

Inflammation in Prostatic Hyperplasia and Carcinoma-Basic Scientific Approach

Chronic inflammation is associated with both benign conditions and cancer. Likewise, inflammatory cells are quite common in benign prostatic hyperplasia (BPH) and prostatic tissue harboring cancer. Triggers that activate inflammatory pathways in the prostate remain a subject of argument and are likely to be multifactorial, some of these being bacterial antigens, different chemical irritations, and metabolic disorders. Acute and chronic inflammation in prostate leads to accumulation of immunocompetent cells, mainly T lymphocytes and macrophages, but also neutrophils, eosinophils, and mast cells, depending on the type of offending agent. Inflammatory processes activate hyperproliferative programs resulting in nodules seen in BPH, but are also important in creating suitable microenvironment for cancer growth and progression. Inflammatory cells have mostly been shown to have a protumoral effect such as tumor-associated macrophages, but some cell types such as mast cells have antitumoral effects. This review outlines the recent findings and theories supporting the role of inflammatory responses as drivers of both benign and malignant epithelial processes in the prostate gland.

Antagonists of growth hormone-releasing hormone inhibit proliferation induced by inflammation in prostatic epithelial cells

The etiology of benign prostatic hyperplasia (BPH) is multifactorial, and chronic inflammation plays a pivotal role in its pathogenesis. Growth hormone-releasing hormone (GHRH) is a hypothalamic neuropeptide that has been shown to act as paracrine/autocrine factor in various malignancies including prostate cancer. GHRH and its receptors are expressed in experimental models of BPH, in which antagonists of GHRH suppressed the levels of proinflammatory cytokines and altered the expression of genes related to epithelial-to-mesenchymal transition (EMT). We investigated the effects of GHRH antagonist on prostatic enlargement induced by inflammation. Autoimmune prostatitis in Balb/C mice was induced by a homogenate of reproductive tissues of male rats. During the 8-wk induction of chronic prostatitis, we detected a progressive increase in prostatic volume reaching 92% at week 8 compared with control (P < 0.001). Daily treatment for 1 mo with GHRH antagonist MIA-690 caused a 30% reduction in prostate volume (P < 0.05). Conditioned medium derived from macrophages increased the average volume of spheres by 82.7% (P < 0.001) and elevated the expression of mRNA for N-cadherin, Snail, and GHRH GHRH antagonist reduced the average volume of spheres stimulated by inflammation by 75.5% (P < 0.05), and TGF-β2 by 91.8% (P < 0.01). The proliferation of primary epithelial cells stimulated by IL-17A or TGF-β2 was also inhibited by 124.1% and 69.9%, respectively. GHRH stimulated the growth of BPH-1 and primary prostate spheres. This study provides evidence that GHRH plays important roles in prostatic inflammation and EMT and suggests the merit of further investigation to elucidate the effects of GHRH antagonists in prostatitis and BPH.

The traditional Korean herbal medicine Ga-Gam-Nai-Go-Hyan suppresses testosterone-induced benign prostatic hyperplasia by regulating inflammatory responses and apoptosis

Benign prostatic hyperplasia (BPH) is a pathological condition that affects the majority of men above the age of 50 years. Pharmacological agents are typically used to treat BPH; however, there are currently no pharmacological agents that are able to completely cure BPH without causing adverse side effects. As a result of these side effects, there is a great interest in developing effective herbal medicines that are able to inhibit the progression of BPH and are safe for long-term use. Ga-Gam-Nai-Go-Hyan (GGN) is a traditional Korean herbal medicine that has been widely used to treat BPH; however, no biological studies have been performed to elucidate the efficacy of GGN. The aim of the present study was to evaluate the efficacy of GGN as a treatment for BPH. GGN administration was demonstrated to significantly decrease prostate weight (P<0.001), the relative prostate weight ratio (P<0.001) and the ratio of prostate weight to body weight (P<0.001). In addition, GGN treatment was revealed to suppress testosterone and dihydrotestosterone serum levels (P<0.001) and the growth of prostatic tissue. GGN also decreased the levels of the two inflammatory proteins (P<0.05), inducible nitric oxide synthase and cyclooxygenase-2, decreased the levels of the two apoptotic suppressors (P<0.05) B-cell lymphoma (Bcl)-2 and Bcl-xL and increased the levels of the pro-apoptotic factors (P<0.05) Bcl-2-associated X protein, caspase-3, caspase-8, Fas, Fas ligand and Fas-associated protein with death domain. The results of the present study suggested that GGN may have suppressive effects on the development of BPH and therefore have the potential to be used for treating BPH.

Immune Infiltration and Prostate Cancer

It is becoming increasingly clear that inflammation influences prostate cancer (PCa) development and that immune cells are among the primary drivers of this effect. This information has launched numerous clinical trials testing immunotherapy drugs in PCa patients. The results of these studies are promising but have yet to generate a complete response. Importantly, the precise immune profile that determines clinical outcome remains unresolved. Individual immune cell types are divided into various functional subsets whose effects on tumor development may differ depending on their particular phenotype and functional status, which is often shaped by the tumor microenvironment. Thus, this review aims to examine the current knowledge regarding the role of inflammation and specific immune cell types in mediating PCa progression to assist in directing and optimizing immunotherapy targets, regimens, and responses and to uncover areas in which further research is needed. Finally, a summary of ongoing immunotherapy clinical trials in PCa is provided.

TLR4 activation by lipopolysaccharide confers survival advantage to growth factor deprived prostate cancer cells

BACKGROUND

Prostate cancer (PCa) cells express Toll-like receptor-4 (TLR4), a known pro-tumorigenic molecule for different cancer cells. The cancer cells residing in the avascular region of the tumor confront various metabolic stresses and continuously adapt mechanisms to overcome them. We hypothesized that TLR4 activation might provide direct survival advantage to metabolically stressed PCa cells.

METHODS

We first investigated the effect of LPS on survival of serum deprived PCa cells. To understand the molecular mechanisms involved in TLR4 mediated PCa survival, we next investigated change in expression of markers for apoptosis, senescence and autophagy. Ultimately, the effect of LPS on established prostate tumors was confirmed in vivo using a syngeneic rat model for PCa.

RESULTS

Lipopolysaccharide (LPS)-mediated TLR4 activation significantly enhanced survival of serum deprived (SD) PC3, DU145 and MAT-LyLu PCa cells. TLR4 inhibition by a specific inhibitor resulted in rapid death of SD-PC3 cells, which was significantly suppressed by LPS. Interestingly, LPS treatment suppressed macroautophagy in SD-PC3 cells and increased expression of CCL2 (C-C motif ligand-2), a known autophagy inhibitor and pro-survival factor. Intra-tumor LPS injection resulted in increased tumor mass, induced TLR4 activation, suppressed autophagy, and increased the macrophage population in MAT-LyLu-tumors.

CONCLUSIONS

Our study reveals that bacterial LPS enhance survival of PCa cells under conditions of nutrient stress through TLR4 activation. Moreover, LPS induces overexpression of CCL2 involved in the suppression of starvation-induced macroautophagy in PCa cells, and enhanced macrophage population in prostate tumors in vivo. Taken together, the current study suggests the importance of bacterial infection or TLR4-activation in prostate cancer pathogenesis.

Bee venom suppresses testosterone-induced benign prostatic hyperplasia by regulating the inflammatory response and apoptosis

Benign prostatic hyperplasia (BPH), which is a common disorder in aging men, involves inflammation that is associated with an imbalance between cell proliferation and cell death. Because current BPH drug treatments have undesirable side effects, the development of well-tolerated and effective alternative medicines to treat BPH is of interest. Bee venom (BV) has been used in traditional medicine to treat conditions, such as arthritis and rheumatism, and pain. Although inflammation has been associated with BPH and BV has strong anti-inflammatory effects, the effects of BV on BPH are not fully understood. Therefore, in this study, we evaluated the efficacy of BV against testosterone-induced BPH in rats. BV decreased prostate weight compared to the untreated group. In addition, BV suppressed serum dihydrotestosterone concentration levels and the levels of proliferating cell nuclear antigen in the histological analysis. Furthermore, BV significantly decreased the levels of the apoptotic suppressors, Bcl-2 and Bcl-xL, and increased the levels of the proapoptotic factors, Bax and caspase-3 activation. These results suggested that BV suppressed the development of BPH and has good potential as a treatment for BPH.

DNA methyl transferase 1 reduces expression of SRD5A2 in the aging adult prostate

5-α Reductase type 2 (SRD5A2) is a critical enzyme for prostatic development and growth. Inhibition of SRD5A2 by finasteride is used commonly for the management of urinary obstruction caused by benign prostatic hyperplasia. Contrary to common belief, we have found that expression of SRD5A2 is variable and absent in one third of benign adult prostates. In human samples, absent SRD5A2 expression is associated with hypermethylation of the SRD5A2 promoter, and in vitro SRD5A2 promoter activity is suppressed by methylation. We show that methylation of SRD5A2 is regulated by DNA methyltransferase 1, and inflammatory mediators such as tumor necrosis factor α, NF-κB, and IL-6 regulate DNA methyltransferase 1 expression and thereby affect SRD5A2 promoter methylation and gene expression. Furthermore, we show that increasing age in mice and humans is associated with increased methylation of the SRD5A2 promoter and concomitantly decreased protein expression. Artificial induction of inflammation in prostate primary epithelial cells leads to hypermethylation of the SRD5A2 promoter and silencing of SRD5A2, whereas inhibition with tumor necrosis factor α inhibitor reactivates SRD5A2 expression. Therefore, expression of SRD5A2 is not static and ubiquitous in benign adult prostate tissues. Methylation and expression of SRD5A2 may be used as a gene signature to tailor therapies for more effective treatment of prostatic diseases.

Human papillomavirus 16 infection as a potential risk factor for prostate cancer: an adaptive meta-analysis

OBJECTIVES

Although an expert review published in 2013 concluded that an association between human papillomavirus (HPV) infection and prostate cancer (PCa) risk had not yet been firmly established, a 2011 systematic review of 14 articles revealed an increased prevalence of HPV-16 DNA in PCa tissues. Another meta-analysis of the related articles is needed to evaluate the potential link between HPV infection and PCa risk.

METHODS

A snowballing search strategy was applied to the previously cited articles in the above-mentioned expert review and systematic review. Additional articles selected for this meta-analysis should fulfill all following inclusion criteria: (a) evaluation of detected HPV-16 DNA in tissue samples and the PCa risk and (b) report of the HPV-16 prevalence in both cancer and control tissues. Estimated summary odds ratios (sOR) with 95% confidence intervals (CI) were calculated using fixed effect or random-effect models.

RESULTS

Hand searching identified 16 new articles. The sOR of the total 30 articles indicated a significant HPV-16 infection-related increase in the PCa risk (sOR, 1.851; 95% CI, 1.353 to 2.532, I(2)=37.82%).

CONCLUSIONS

These facts provide additional supportive evidence for a causal role of HPV-16 infection in prostate carcinogenesis. As the PCa incidence rates have increased rapidly in Asian countries, including Korea, during the last several decades, further studies of HPV-related PCa carcinogenesis may be necessary.

Balancing the innate immune system in tumor development

Cells of the innate immune system have a dual role in cancer development in both tumor initiation and progression. Innate immune cells can, on the one hand, aid malignant transformation and tumor outgrowth and, on the other hand, prevent tumor progression. The innate immune system has the ability to tune the inflammatory response and is a key player in cancer-related inflammation, which can precede the development of malignancy or be induced by oncogenic changes promoting a protumor inflammatory milieu. In this review, we discuss the emerging cellular and molecular mechanisms of the innate immune system and inflammation in tumor initiation and progression, and point to the outstanding questions that remain.

DNA damage response and prostate cancer: defects, regulation and therapeutic implications

DNA damage response (DDR) includes the activation of numerous cellular activities that prevent duplication of DNA lesions and maintain genomic integrity, which is critical for the survival of normal and cancer cells. Specific genes involved in the DDR such as BRCA1/2 and P53 are mutated during prostate cancer progression, while various oncogenic signaling such as Akt and c-Myc are activated, enhancing the replication stress and increasing the genomic instability of cancer cells. These events may render prostate cancer cells particularly sensitive to inhibition of specific DDR pathways, such as PARP in homologous recombination (HR) DNA repair and Chk1 in cell cycle checkpoint and DNA repair, creating opportunities for synthetic lethality or synergistic cytotoxicity. Recent reports highlight the critical role of androgen receptor (AR) as a regulator of DDR genes, providing a rationale for combining DNA-damaging agents or targeted DDR inhibitors with hormonal manipulation or AR inhibition as treatment for aggressive disease. The aims of this review are to discuss specific DDR defects in prostate cancer that occur during disease progression, to summarize recent advances in understanding the regulation of DDR in prostate cancer, and to present potential therapeutic opportunities through combinational targeting of the intact components of DDR signaling pathways.