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The Prostate

Wiley Online Library : The Prostate

Published: 2018-03-01T00:00:00-05:00


A TRAMP-derived orthotopic prostate syngeneic (TOPS) cancer model for investigating anti-tumor treatments


Background Patients with advanced prostate cancer have limited curative options, therefore new treatments are needed. Mouse models play a pivotal role in the discovery and development of new treatments. In the present study, a TRAMP-derived Orthotopic Prostate Syngeneic (TOPS) mouse model was developed and found to provide a consistent means of monitoring tumor and metastatic responses to novel treatments. Methods The mouse TOPS model was generated using luciferase transduced TRAMP-C2 prostate cancer cells that were orthotopically injected into Bl6 mice by ultrasound guidance. Tumor growth and development was monitored using ultrasound and bioluminescence imaging. Results Tumors and metastases were consistently established and increases in tumor size correlated with increases in bioluminescence. In addition, when mice with an established tumor were castrated, tumor progression mirrored clinical progression. We further treated the TOPS model with an oncolytic Herpes Simplex virus and showed that we were able to monitor the therapeutic effect of the orthotopic tumor after virus treatment through IVIS imaging system. Conclusion We have developed a powerful animal model to advance the current selection of effective treatments for patients with advanced prostate cancer.

The prognosis of different distant metastases pattern in prostate cancer: A population based retrospective study


Background The present of metastases is a poor prognostic factor in prostate cancer, but the prognostic impact of different distant metastases pattern is unclear. The aim of this study is to investigate the impact of different distant metastases pattern on the survival of patients with stage IV prostate cancer. Methods Data queried for this study include prostate cancer (2010-2014) from the Surveillance, Epidemiology, and End Results (SEER) program. Metastatic distribution information was provided for bone, brain, liver and lung. The overall survival was calculated by the Kaplan-Meier method. Multivariable Cox regression models were used to analyze survival outcome and risk factors. Results A total of 265 900 eligible patients were identified from SEER database. Among these patients, stage of IV prostate cancer accounted for 7.53% (20 034/265 900) at diagnosis. Patients who suffered metastasis to either one of the four organs occupied 61.24% (12 268/20 034) in stage of IV patients. Comparing with other three single metastases, the patients with liver metastasis exhibited worst OS whose mean survival was 17.529 months (P < 0.001). The mean survival of metastases with bong and lung was 25.238 months, which was the best survival of the six forms with two metastatic sites (P < 0.001). The results of univariate survival analysis showed that metastatic forms, race, N-classification and differentiated grade did not have impact on the overall survival of patients with three metastatic sites (all, P > 0.05). Conclusions In analysis of both one and two metastatic sites, patients with liver metastasis seemed to have worse survival outcome. On the other hand, bone metastasis had better outcome than other three visceral metastases. Knowledge of these differences in metastatic patterns may help to better guide pre-treatment evaluation of prostate cancer and make determination regarding curative-intent interventions.

Circulating tumor cells and survival in abiraterone- and enzalutamide-treated patients with castration-resistant prostate cancer


Background The outcome to treatment administered to patients with metastatic castration-resistant prostate cancer (mCRPC) greatly differs between individuals, underlining the need for biomarkers guiding treatment decision making. Objective To investigate the prognostic value of circulating tumor cell (CTC) enumeration and dynamics, in the context of second-line endocrine therapies (ie, abiraterone acetate or enzalutamide), irrespective of prior systemic therapies. Design, Settings, and Participants In a prospective, multicentre study blood samples for CTC enumeration were collected from patients with mCRPC at baseline (n = 174). In patients who responded for minimally 10-12 weeks a follow-up sample was collected. Outcome Measurements and Statistical Analysis For baseline analysis, patients were stratified in <5 or ≥5 CTCs/7.5 mL, whereas for the analysis of CTC dynamics at 10-12 weeks, in patients with stable, increasing or decreasing CTC counts. Progression-free survival (PFS), overall survival (OS), and PSA changes at 10-12 weeks were compared between groups. Results Patients demonstrating increasing CTCs on therapy had a shorter median PFS (4.03 vs 12.98 vs 13.67 months, HR 3.6, 95%CI 1.9-6.8; P < 0.0001) and OS (11.2 months vs not reached, HR 9.5, 95%CI 3.7-24; P < 0.0001), compared to patients with decreasing or stable CTCs. Multivariable Cox regression showed that prior chemotherapy (HR 4.1, 95%CI 1.9-8.9; P = 0.0003), a high baseline CTC count (HR 1.5, 95%CI 1.2-1.9; P = 0.002) and increasing CTCs at follow-up (HR 3.3, 95%CI 1.4-7.6; P = 0.005) were independent predictors of worse PFS. Previous chemotherapy (HR 7, 95%CI 1.9-25; P = 0.003), high baseline CTC counts (HR 2.2, 95%CI 1.4-3.7; P = 0.002) and increasing CTCs during therapy (HR 4.6, 95%CI 1.4-15; P = 0.01) were independently associated with shorter OS. ≥30% and ≥50% PSA responses less frequently occurred in patients with CTC inclines at 10-12 weeks on therapy (χ2 test: P < 0.01). Conclusions CTC dynamics during therapy are associated with PSA response and provide independent clinical prognostication over PSA declines. Hence the study demonstrates the pharmacodynamic properties of CTCs.

Osteoblast-derived factors promote metastatic potential in human prostate cancer cells, in part via non-canonical transforming growth factor β (TGFβ) signaling


Background Transforming growth factor β (TGFβ) functions as a double-edged sword in prostate cancer tumorigenesis. In initial stages of the disease, TGFβ acts as a growth inhibitor upon tumor cells, whereas it in later stages of disease rather promotes invasion and metastatic potential. One well-known cellular source of TGFβ in the bone metastatic site is the bone-forming osteoblasts. Here we have studied the effects by osteoblast-derived factors on metastatic potential in several human prostate cancer cell lines. Methods Effects on metastatic potential in prostate cancer cells by osteoblast-derived factors were studied in vitro using several methods, including Transwell migration and evaluation of formation of pro-migratory protrusions. Confocal microscopy was used to evaluate possible changes in differentiation state in tumor cells by analysis of markers for epithelial-to-mesenchymal transition (EMT). The Matrigel-on-top 3D culture method was used for further assessment of metastatic characteristics in tumor cells by analysis of formation of filopodium-like protrusions (FLPs). Results Osteoblast-derived factors increased migration of PC-3U cells, an effect less prominent in cells overexpressing a mutated type I TGFβ receptor (TβRI) preventing non-canonical TRAF6-dependent TGFβ signaling. Osteoblast-derived factors also increased the formation of long protrusions and loss of cell-cell contacts in PC-3U cells, suggesting induction of a more aggressive phenotype. In addition, treatment with TGFβ or osteoblast-derived factors of PC-3U cells in Matrigel-on-top 3D cultures promoted formation of FLPs, previously shown to be essential for metastatic establishment. Conclusions These findings suggests that factors secreted from osteoblasts, including TGFβ, can induce several cellular traits involved in metastatic potential of PC-3U cells, further strengthening the role for bone cells to promote metastatic tumor cell behavior.

Circulating microRNAs in plasma as potential biomarkers for the early detection of prostate cancer


Background MicroRNAs (miRNAs) have been linked to prostate cancer (PC) risk; however, their role as a screening biomarker for PC has yet to be determined. We examined whether circulating miRNAs in plasma could be potential biomarkers for the early detection of PC among men undergoing prostate needle biopsy. Methods Men who had a prostate biopsy due to an abnormal screening test were recruited. Linear regression was used to examine the association between miRNAs in plasma and PC status and to model individual miRNA expression on serum PSA and age to calculate the partial correlation coefficient (r). Results There were 134 men, aged 46-86 years, included, with 66 men with a PC diagnosis (cases), eight men with no PC diagnosis but atypical lesion, and 60 men without a PC diagnosis (controls). The most statistically significant PC circulating miRNAs were miR-381, miR-34a, miR-523, miR-365, miR-122, miR-375, miR-1255b, miR-34b, miR-450b-5p, and miR-639 after adjusting for age (P-values ≤0.05); however, they were no longer statistically significant after P-value adjustment for multiple comparisons. MiR-671-3p was differentially expressed between black and white cases (P-value = 0.03). Moderate positive correlations with serum PSA were observed for miR-381 overall and among controls (r = 0.43-0.60; P-values ≤0.05) and miR-34a among cases (r = 0.46; P-value = 0.02). Conclusions There was no miRNA associated with PC diagnosis after adjusting for age and P-values; however, moderate correlations between miRNAs and serum PSA were observed. Further investigation between miRNAs and PC risk is warranted in a larger population at high risk for PC.

Metastatic prostate cancer-associated P62 inhibits autophagy flux and promotes epithelial to mesenchymal transition by sustaining the level of HDAC6


Background P62 (also named sequestosome-1, SQSTM1) is involved in autophagy regulation through multiple pathways. It interacts with autophagosomes-associated LC3-II and ubiquitinated protein aggregates to engulf the aggregates in autophagosomes, interacts with HDAC6 to inhibit its deacetylase activity to maintain the levels of acetylated α-tubulin and stabilities of microtubules to enhance autophagosome trafficking, and regulates autophagy initiation and cell survival. We performed immunohistochemistry staining of P62 in prostate tissues from prostate cancer patients and found that levels of P62 in patients with prostate adenocarcinomas (PCA) are significantly higher than those in patients with benign prostate hyperplasia (BPH). High levels of P62 predict high tumor grade and high intensity of metastasis. Methods We created prostate cancer cell lines stably overexpressing P62 and then suppress the expression of P62 in the cell line stably overexpressing P62 with CRISPR technology. Cell proliferation assay with crystal violet, cell migration assay, cell invasion assay, Western blot analysis, and confocal fluorescent microscopy were conducted to test the impact of altered levels of P62 on the growth, migration, invasion, epithelial-to-mesenchymal transition, autophagy flux, HDAC6 activity, and microtubular acetylation of cancer cells. Results P62 increased the levels of HDAC6 and reduced the acetylation of α-tubulin and the stability of microtubules. Consequently, high levels of P62 caused a promotion of epithelial-to-mesenchymal transition in addition to an impairment of autophagy flux, and further led to an enhancement of proliferation, migration, and invasion of prostate cancer cells. Conclusion P62 promotes metastasis of PCA by sustaining the level of P62 to inhibit autophagy and promote epithelial-to-mesenchymal transition.

Accuracy of standardized 12-core template biopsies versus non-standardized biopsies for detection of Epstein Grade 5 prostate cancer regarding the histology of the prostatectomy specimen


Objective To evaluate the effectiveness of EAU Guideline compliant transrectal ultrasound-guided 12-core prostate biopsies for detection of highly aggressive Epstein Grade 5 (Gleason Score 9-10) prostate cancer. Methods Two hundred ninety-nine patients, treated by radical prostatectomy for prostate cancer, have been prospectively recorded in a database and were evaluated for this study. Pre-operatively, all patients received transrectal ultrasound-guided biopsies according to inhomogeneous templates chosen by the referring urologist. We evaluated the outcomes according to a stratified group-analysis: Group 1 received less than 12 biopsies, Group 2 received more than 12 biopsies, and Group 3 received exactly 12 biopsies, according to the EAU Guidelines template. After surgical removal of the prostate, 12 EAU Guideline-templated biopsies were performed in all prostatectomy specimens, directly after the surgery. Pre-operative and post-operative Epstein Grade 5 biopsy detection rates were thereafter correlated with these prostatectomy specimens. Results In prostatectomy specimens, the histology of 12 patients (4.0%) were Epstein Grade 1, 31 patients (10.5%) were Epstein Grade 2, 190 patients (63.5%) were Epstein Grade 3, 27 patients (9%) were Epstein Grade 4, and 39 patients (13%) were Epstein Grade 5. The detection rate of Epstein Grade 5 compared to the radical prostatectomy specimen was: Group 1: 23.0% pre-operatively and 61.5% post-operatively, Group 2: 33.3% pre-operatively and 58.3% post-operatively; and Group 3: 57.1% pre-operatively and 64.2% post-operatively. Conclusion Detection rates of highly aggressive Epstein Grade 5 prostate cancer vary considerably according to the biopsy technique. EAU Guideline compliant 12-core template biopsies increase the detection rates of Epstein Grade 5 prostate cancer.

p62 as a therapeutic target for inhibition of autophagy in prostate cancer


Background To test the hypothesis that p62 is an optimal target for autophagy inhibition and Verteporfin, a clinically available drug approved by FDA to treat macular degeneration that inhibits autophagy by targeting p62 protein, can be developed clinically to improve therapy for advanced prostate cancer. Methods Forced expression of p62 in PC-3 cells and normal prostate epithelial cells, RWPE-1 and PZ-HPV7, were carried out by transfection of these cells with pcDNA3.1/p62 or p62 shRNA plasmid. Autophagosomes and autophagic flux were measured by transfection of tandem fluorescence protein mCherry-GFP-LC3 construct. Apoptosis was measured by Annexin V/PI staining. Tumorigenesis was measured by a xenograft tumor growth model. Results Verteporfin inhibited cell growth and colony formation in PC-3 cells. Verteporfin generated crosslinked p62 oligomers, resulting in inhibition of autophagy and constitutive activation of Nrf2 as well as its target genes, Bcl-2 and TNF-α. In normal prostate epithelial cells, forced expression of p62 caused constitutive Nrf2 activation, development of apoptosis resistance, and Verteporfin treatment exhibited inhibitory effects. Verteporfin treatment also inhibited starvation-induced autophagic flux of these cells. Verteporfin inhibited tumorigenesis of both normal prostate epithelial cells with p62 expression and prostate cancer cells and decreased p62, constitutive Nrf2, and Bcl-xL in xenograft tumor tissues, indicating that p62 can be developed as a drug target against prostate cancer. Conclusions p62 has a high potential to be developed as a therapeutic target. Verteporfin represents a prototypical agent with therapeutic potential against prostate cancer through inhibition of autophagy by a novel mechanism of p62 inhibition.

Intraductal/ductal histology and lymphovascular invasion are associated with germline DNA-repair gene mutations in prostate cancer


Background Germline mutations in genes mediating DNA repair are common in men with recurrent and advanced prostate cancer, and their presence may alter prognosis and management. We aimed to define pathological and clinical characteristics associated with germline DNA-repair gene mutations, to facilitate selection of patients for germline testing. Methods We retrospectively evaluated 150 unselected patients with recurrent or metastatic prostate cancer who were offered germline genetic testing by a single oncologist using a clinical-grade assay (Color Genomics). This platform utilizes next-generation sequencing from saliva to interrogate 30 cancer-susceptibility genes. Presence or absence of a deleterious germline mutation was correlated with histological and clinical characteristics, and with family history of cancer. All patients with DNA-sequence alterations (pathogenic or variants) were offered genetic counseling. Results Between July 2016 and July 2017, 150 consecutive patients underwent germline testing; pathogenic mutations were identified in 21 men (14%). Among those with germline mutations, 9 (43%) were in BRCA2, 3 (14%) were in ATM, 3 (14%) were in CHEK2, and 2 (9%) were in BRCA1. While there were no associations between germline mutations and age, tumor stage, Gleason sum or family history; mutation-positive patients had lower median PSA levels at diagnosis (5.5 vs 8.6 ng/mL, P = 0.01) and unique pathologic features. Namely, men with germline mutations were more likely to harbor intraductal/ductal histology (48% vs 12%, P < 0.01) and lymphovascular invasion (52% vs 14%, P < 0.01). Finally, 44% of patients with a positive germline test would not have been offered genetic screening according to current National Comprehensive Cancer Network (NCCN) guidelines. Conclusions Presence of intraductal/ductal histology and lymphovascular invasion appear to be associated with pathogenic germline DNA-repair gene mutations in men with prostate cancer, and identification of these features may help to select patients for germline testing. NCCN guidelines may be inadequate in predicting which prostate cancer patients should undergo genetic screening.

Anatomical localization and clinical impact of sentinel lymph nodes based on patterns of pelvic lymphatic drainage in clinically localized prostate cancer


Background Although sentinel lymph node in prostate has been generating renewed interest, its significance remains controversial due to inadequate evidence. Methods We reviewed a prospective cohort of 50 consecutive patients with intermediate- to high-risk localized prostate cancer who had undergone laparoscopic radical prostatectomy. Sentinel lymph node biopsy by fluorescence detection using intraoperative imaging with indocyanine green and backup extended pelvic lymph node dissection were conducted prior to prostatectomy. Intraoperative and pathological findings were elaborated and compared for confirmation. Results Sentinel lymph nodes were successfully identified in 47 patients (94%). A median of four sentinel lymph nodes was detected per patient. Lymph node metastasis was confirmed in six patients (12%), all of whom had positive sentinel lymph nodes. Three typical pathways of lymphatic drainage related to sentinel lymph nodes from the prostate were recognized. Ninety-one percent of the positive sentinel lymph nodes (10/11) were located at two predominant sites along these characteristic lymphatic pathways. One site was the junctional nodes, located at the junction between internal and external iliac vessels. The other was the distal internal iliac nodes, located along the inferior vesical artery. Conclusions Over 90% of positive sentinel lymph nodes were identified at two predominant sites. Priority should be given to the removal of these sentinel lymph nodes, which are located closer to the prostate, in pelvic lymph node dissection. Particular attention should be paid to identifying these nodes to reduce the possibility of overlooking lymph node metastasis.

Rare germline mutations in African American men diagnosed with early-onset prostate cancer


Background African Americans have both a higher incidence of prostate cancer and greater disease-specific mortality compared with non-Hispanic whites. Historically, the investigation of the contribution of rare genetic variants to prostate cancer in African American men has been hampered by low participation in large genetic studies, particularly those focused on early-onset and familial disease. Methods We sequenced 160 genes purported to be involved in carcinogenic pathways in germline DNA samples collected from 96 African American men diagnosed with early-onset prostate cancer (≤55 years at diagnosis). REVEL software was used to determine the pathogenic potential of observed missense variants. Results We observed three protein-truncating mutations, one in BRCA2 and two in BRIP1 in three African American men diagnosed with early-onset prostate cancer. Furthermore, we observed five rare, mostly private, missense variants among four genes (BRCA1, BRCA2, PMS2, and ATM) that were predicted to be deleterious and hence likely pathogenic in our patient sample. Conclusions Protein-truncating mutations in BRCA2 and BRIP1 were discovered in African American men diagnosed with early-onset prostate cancer. Further study is necessary to determine the role of rare, missense variants to prostate cancer incidence, and progression in this group of high-risk men.

Matrine inhibits the progression of prostate cancer by promoting expression of GADD45B


Background Matrine is a naturally occurring alkaloid extracted from the Chinese herb Sophora flavescens. It has been demonstrated to exhibit antiproliferative properties, promote apoptosis, and inhibit cell invasion in a number of cancer cell lines by modulating the NF-κB pathway to downregulate the expression of MMP2 and MM9. It has also been shown to improve the efficacy of chemotherapy when it is combined with other chemotherapy drugs. However, the therapeutic potential of matrine for prostate cancer needs to be further studied. Methods We analyzed KEGG pathways of differential gene expression between matrine-treated and untreated prostate cancer cell lines and identified GADD45B as one of major target genes of matrine based on its role in apoptosis and prognosis value for prostate cancer patients in TCGA database. We further analyzed the expression of GADD45B protein in a tissue microarray and mRNA in TCGA database, and tested the synergistic impacts of matrine and GADD45B overexpression on proliferation, apoptosis, migration and invasion of prostate cancer cell DU145. Results Matrine promoted the expression of GADD45B, a tumor suppressive gene that is involved in the regulation of cell cycle, DNA damage repair, cell survival, aging, apoptosis and other cellular processes through p38/JNK, ROS-GADD45B-p38, or other signal pathways. Although GADD45B is elevated in prostate cancer tissues, levels of GADD45B in prostate tumor tissues are reduced at late stage of tumor invasion, and higher levels of GADD45B predict better survivals of prostate cancer patients. Conclusions Matrine may be used to treat prostate cancer patients to increase the levels of GADD45B to inhibit tumor invasion and improve patient survivals.

Genetic risk of prostate cancer in ugandan men


Background Men of African-ancestry have elevated prostate cancer (PCa) incidence and mortality compared to men of other racial groups. There is support for a genetic contribution to this disparity, with evidence of genetic heterogeneity in the underlying risk alleles between populations. Studies of PCa among African men may inform the contribution of genetic risk factors to the elevated disease burden in this population. Methods We conducted an association study of >100 previously reported PCa risk alleles among 571 incidence cases and 485 controls among Uganda men. Unconditional logistic regression was used to test genetic associations and a polygenic risk score (PRS) was derived to assess the cumulative effect of the known risk alleles in association with PCa risk. In an exploratory analysis, we also tested associations of 17 125 421 genotyped and imputed markers genome-wide in association with PCa risk. Results Of the 111 known risk loci with a frequency >1%, 75 (68%) had effects that were directionally consistent with the initial discovery population,14 (13%) of which were nominally significantly associated with PCa risk at P < 0.05. Compared to men with average risk (25th-75th percentile in PRS distribution), Ugandan men in the top 10% of the PRS, constructed of alleles outside of 8q24, had a 2.9-fold (95%CI: 1.75, 4.97) risk of developing PCa; risk for the top 10% increased to 4.86 (95%CI: 2.70, 8.76) with the inclusion of risk alleles at 8q24. In genome-wide association testing, the strongest associations were noted with known risk alleles located in the 8q24 region, including rs72725854 (OR = 3.37, P = 2.14 × 10−11) that is limited to populations of African ancestry (6% frequency). Conclusions The ∼100 known PCa risk variants were shown to effectively stratify PCa risk in Ugandan men, with 10% of men having a >4-fold increase in risk. The 8q24 risk region was also found to be a major contributor to PCa risk in Ugandan men, with the African ancestry-specific risk variant rs72725854 estimated to account for 12% of PCa in this population.

Differential role of PTEN in transforming growth factor β (TGF-β) effects on proliferation and migration in prostate cancer cells


Background Transforming growth factor-β (TGF-β) acts as a tumor suppressor in normal epithelial cells but as a tumor promoter in advanced prostate cancer cells. PI3-kinase pathway mediates TGF-β effects on prostate cancer cell migration and invasion. PTEN inhibits PI3-kinase pathway and is frequently mutated in prostate cancers. We investigated possible role(s) of PTEN in TGF-β effects on proliferation and migration in prostate cancer cells. Methods Expression of PTEN mRNA and proteins were determined using RT-PCR and Western blotting in RWPE1 and DU145 cells. We also studied the role of PTEN in TGF-β effects on cell proliferation and migration in DU145 cells after transient silencing of endogenous PTEN. Conversely, we determined the role of PTEN in cell proliferation and migration after over-expression of PTEN in PC3 cells which lack endogenous PTEN. Results TGF-β1 and TGF-β3 had no effect on PTEN mRNA levels but both isoforms increased PTEN protein levels in DU145 and RWPE1 cells indicating that PTEN may mediate TGF-β effects on cell proliferation. Knockdown of PTEN in DU145 cells resulted in significant increase in cell proliferation which was not affected by TGF-β isoforms. PTEN overexpression in PC3 cells inhibited cell proliferation. Knockdown of endogenous PTEN enhanced cell migration in DU145 cells, whereas PTEN overexpression reduced migration in PC3 cells and reduced phosphorylation of AKT in response to TGF-β. Conclusion We conclude that PTEN plays a role in inhibitory effects of TGF-β on cell proliferation whereas its absence may enhance TGF-β effects on activation of PI3-kinase pathway and cell migration.

MicroRNA181c inhibits prostate cancer cell growth and invasion by targeting multiple ERK signaling pathway components


Background The ERK signaling pathway is frequently deregulated in tumorigenesis, mostly by classical mechanisms such as gene mutation of its components (eg, RAS and RAF). However, whether and how multiple key components of ERK pathway are regulated by microRNAs are not clear. Methods We firstly predicted post-transcriptional regulation of multiple key components of the ERK signaling pathway by miR181c through bioinformatics analysis, and then confirmed the post-transcriptional regulation by dual luciferase reporter gene assays and Western blot analysis. The biological effects of miR181c on prostate cancer cell proliferation, apoptosis, migration, and invasion were measured by CCK-8 assay, flow cytometry, wound scratch assay, transwell cell migration, and invasion assays. Results miR181c post-transcriptionally regulated multiple key members of the ERK signaling pathway, including extracellular signal-regulated kinase 2 (ERK2), ribosomal S6 kinase 2 (RSK2), serum response factor (SRF), and FBJ murine osteosarcoma viral oncogene homolog (c-Fos). Ectopic expression of miR181c mimics effectively suppressed prostate cancer cell proliferation, migration, and invasion, but promoted cell apoptosis. Furthermore, miR181c treatment combined with the multi-kinase inhibitor sorafenib significantly enhanced these anti-tumor effects. Conclusions Downregulation of miR181c results in deregulated ERK signaling and promotes prostate cancer cell growth and metastasis.

Adipocytes affect castration-resistant prostate cancer cells to develop the resistance to cytotoxic action of NK cells with alterations of PD-L1/NKG2D ligand levels in tumor cells


Background Obesity affects prostate cancer (PCa) progression, and the periprostatic adipose tissue adjacent to the prostate is considered a driving force of disease progression. Adipocytes are the main cell population in adipose tissues and their paracrine role contributes to PCa progression, however its implication in modulating immune reactions remains largely unknown. We investigated the adipocyte role in controlling the susceptibility of castration-resistant PCa (CRPC) cells to the cytotoxic action of natural killer (NK) cells. Methods Using primary NK cells as the NK cell source, NK cell cytotoxicities to CRPC cells, either control media treated or adipocyte-conditioned media (CM) treated, were tested in lactate dehydrogenase (LDH) release-based assays. The levels of programmed death receptor ligand (PD-L1) and NK group 2D (NKG2D) ligands in adipocyte CM-treated CRPC cells were analyzed in qPCR analyses. Effects of blocking adipocyte action on altering PD-L1/NKG2D ligand levels and the susceptibility of CRPC cells to NK cell cytotoxicity were investigated. Results We found NK cell cytotoxicity to CRPC cells decreases when tumor cells are treated with adipocyte CM associated with PD-L1 and NKG2D ligand level alterations. Further, we discovered that the JAK/Stat3 signaling pathway was responsible for the adipocyte CM effect. Two adipokine molecules, IL-6 and leptin, were shown to be important in activation of the JAK/Stat3 signaling in CRPC cells to modulate the PD-L1/NKG2D ligand level alteration. Adding the inhibitors of JAK/Stat3 signaling or neutralizing antibodies of IL-6 or leptin increased the susceptibility of CRPC cells to NK cell action. Conclusions Blocking the adipocyte effect by inhibiting the IL-6/leptin-JAK/Stat3 signaling axis may enhance NK cell mediated immunity to CRPC cells and this strategy may help to develop future therapeutics to treat obese PCa patients.

Epigenetic markers in circulating cell-free DNA as prognostic markers for survival of castration-resistant prostate cancer patients


Background : Noninvasive biomarkers to guide personalized treatment for castration-resistant prostate cancer (CRPC) are needed. In this study, we analyzed hypermethylation patterns of two genes (GSTP1 and APC) in plasma cell-free DNA (cfDNA) of CRPC patients. The aim of this study was to analyze the cfDNA concentrations and levels of the epigenetic markers and to assess the value of these biomarkers for prognosis. Methods : In this prospective study, patients were included before starting new treatment after developing CRPC. The blood samples were collected prior to start of the treatment and at three time points thereafter. cfDNA was extracted from 1.5 mL of plasma and before performing a methylation-specific PCR, bisulfate modification was carried out. Results : The median levels of cfDNA, GSTP1, and APC copies in the baseline samples of CRPC patients (n = 47) were higher than in controls (n = 30). In the survival analysis, the group with baseline marker levels below median had significant less PCa-related deaths (P-values <0.02) and did not reach the median survival point. The survival distributions for the groups were statistically significant for the cfDNA concentration, GSTP1 and APC copies, as well as PSA combined with GSTP1 + APC (P-values <0.03). Furthermore, there were strong positive correlations between PSA and marker response after starting treatment (P-values <0.04). Conclusions : In conclusion, this study showed the kinetics of methylated cfDNA (GSTP1 and APC) in plasma of CRPC patients after starting treatment. Furthermore, the value of the markers before treatment is prognostic for overall survival. These results are promising for developing a test to guide treatment-decision-making for CRPC patients.

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Capillarisin blocks prostate-specific antigen expression on activation of androgen receptor in prostate carcinoma cells


Background Capillarisin (Cap), an active ingredient of Artemisia capillaris extracts, has known for its anti-inflammatory, antioxidant, and anticancer properties. Functions of Cap in prostate cancer are not clear. We investigate effects of Cap on downregulation of prostate specific antigen (PSA) via modulation of androgen receptor (AR) in prostate carcinoma cells. Methods Cell proliferation was measured by water-soluble tetrazolium-1 (WST-1) cell proliferation assays. The PSA and AR expressions were assessed by immunoblotting and RT-qPCR assays. Effects of Cap on PSA expressions were determined by ELISA, immunoblotting, and reporter assays. Co-immunoprecipitation and immunoblotting assays were used to define the effects of Cap on dissociation of AR-heat shock protein 90 (Hsp90) interaction. Results Cap inhibited LNCaP cell growth in a dose- and/or time-dependent way without inducing poly ADP-Ribose Polymerase (PARP) cleavage. Cap not only effectively suppressed AR and PSA protein expressions, but also attenuated activations of synthetic androgen (R1881) on PSA promoter activity dose- and time-dependently. The Cap pretreatment abrogated effects of R1881 on AR activity by reducing AR translocation to the nucleus. Immunoblotting assays indicated that Cap promoted a degradation of AR proteins dose-dependently in either cycloheximide pretreated-LNCaP cells or AR-ectopic expressed PC-3 cells. Pretreatment of MG132, a proteasome inhibitor, attenuated effect of Cap on AR degradation. Cap lessened AR stability by dissociation of AR-Hsp90 interaction. Conclusions Our results indicated that Cap inhibited growth of LNCaP cells. Cap effectively suppressed androgen activation on AR-mediated transactivation, which is AR-dependent through AR degradation and dissociation of AR-Hsp90 in prostate carcinoma cells.

Systemic immune-inflammation index predicts the combined clinical outcome after sequential therapy with abiraterone and docetaxel for metastatic castration-resistant prostate cancer patients


Objective To compare the antitumor effect of abiraterone (AA) followed by docetaxel-prednisone (DP) or vice versa in metastatic castration-resistant prostate cancer (mCRPC) patients, and explored factors that might predict combined PSA-PFS, combined rPFS and OS. Patients and Methods We retrospectively analyzed mCRPC patients treated with sequential therapy using DP followed by AA or vice versa. Patients who had received enzalutamide or cabazitaxel were excluded. The primary outcome measure was overall survival (OS). The combined PSA progression-free survival (PSA-PFS), combined radiographic PFS (rPFS), and OS of AA-to-DP were compared to the reverse sequence using Kaplan-Meier curves with log-rank statistics. Univariable and multivariable Cox regression analyses were performed to determine prognostic factors that were associated with combined PSA-PFS, combined rPFS and OS. Results A total of 104 mCRPC patients who began treatment between 2013 and 2017 were identified: 42 were in the DP-to-AA group and 62 were in the AA-to-DP group. There was no significant difference of baseline clinical characteristics between AA-to-DP and DP-to-AA group. In addition, there was no significant difference in combined PSA-PFS (AA-to-DP: 12.5 [11.4-13.6] vs DP-to-AA: 13.2 [10.9-15.5] months [P = 0.127]), combined rPFS (AA-to-DP: 12.2 [10.9-13.4] vs DP-to-AA: 11.2 [8.9-13.5] months [P = 0.183]) and OS (AA-to-DP: 23.3 [19.7-26.9] vs DP-to-AA: 22.9 [22.1-23.7] months [P = 0.213]) between the two treatment sequences in Kaplan-Meier analysis. In multivariate Cox regression analysis, high systematic Immune-Inflammation Index (SII) level, which was calculated by P (platelet) × N (neutrophil)/L(lymphocyte), remained significant predictors of OS, combined rPFS and combined PSA-PFS. Conclusion In this study, we did not observe differences in clinical outcomes based on alternative sequencing of AA and DP in mCRPC patients. The ability to tolerate side effects and patient preference may be used to determine the treatment sequencing. In addition, high pretreatment SII level is a negative independent prognosticator of survival outcomes in mCRPC with sequential therapy using DP followed by AA or vice versa, which might guide clinicians select the best treatment.

Prostate tumors downregulate microseminoprotein-beta (MSMB) in the surrounding benign prostate epithelium and this response is associated with tumor aggressiveness


Background Microseminoprotein-beta (MSMB) is a major secretory product from prostate epithelial cells. MSMB synthesis is decreased in prostate tumors in relation to tumor grade. MSMB levels are also reduced in the circulation and MSMB is therefore used as a serum biomarker for prostate cancer. We hypothesized that cancers induce a reduction in MSMB synthesis also in the benign parts of the prostate, and that the magnitude of this response is related to tumor aggressiveness. Reduced levels of MSMB in the circulation could therefore be a consequence of reduced MSMB expression not only in tumor tissue but also in the benign prostate tissue. Methods MSMB expression was analyzed in prostatectomy specimens from 36 patients using immunohistochemistry and qRT-PCR. MSMB expression in the benign prostate tissue was analyzed in relation to Gleason score, tumor stage, and distance to the tumor. Furthermore, Dunning rat prostate tumors with different aggressiveness were implanted into the prostate of Copenhagen rats to study if this affected the MSMB expression in the tumor-adjacent benign rat prostate tissue. Results In prostatectomy specimens, MSMB expression was reduced in prostate tumors but also in the tumor-adjacent benign parts of the prostate. The reduction in tumor MSMB was related to tumor grade and stage, and the reduction in the benign parts of the prostate to tumor grade, stage, and distance to the tumor. Implantation of Dunning cancer cells into the rat prostate resulted in reduced MSMB protein levels in the tumor-adjacent benign prostate tissue. Rapidly growing and metastatic MatLyLu tumors had a more pronounced effect than slow-growing non-metastatic G tumors. Conclusion Our data suggest that aggressive prostate tumors suppress MSMB synthesis in the benign prostate and that this could explain why serum levels of MSMB are decreased in prostate cancer patients. This study suggests that markers for aggressive cancer can be found among factors altered in parallel in prostate tumors and in the adjacent benign tissue.

Validation of histone deacetylase 3 as a therapeutic target in castration-resistant prostate cancer


Background Whereas the androgen receptor (AR) signaling axis remains a therapeutic target in castration-resistant prostate cancer (CRPC), the emergence of AR mutations and splice variants as mechanisms underlying resistance to contemporary inhibitors of this pathway highlights the need for new therapeutic approaches to target this disease. Of significance in this regard is the considerable preclinical data, indicating that histone deacetylase (HDAC) inhibitors may have utility in the treatment of CRPC. However, the results of clinical studies using HDAC inhibitors (directed against HDAC1, 2, 3, and 8) in CRPC are equivocal, a result that some have attributed to their ability to induce an epithelial to mesenchymal transition (EMT) and neuroendocrine differentiation. We posited that it might be possible to uncouple the beneficial effects of HDAC inhibitors on AR signaling from their undesired activities by targeting specific HDACs as opposed to using the pan-inhibitor strategy that has been employed to date. Methods The relative abilities of pan- and selective-Class I HDAC inhibitors to attenuate AR-mediated target gene expression and proliferation were assessed in several prostate cancer cell lines. Small interfering RNA (siRNA)-mediated knockdown approaches were used to confirm the importance of of HDAC 1, 2, and 3 expression in these processes. Further, the ability of each HDAC inhibitor to induce the expression of EMT markers (RNA and protein) and EMT-like phenotype(s) (migration) were also assessed. The anti-tumor efficacy of a HDAC3-selective inhibitor, RGFP966, was compared to the pan-HDAC inhibitor Suberoylanilide Hydroxamic Acid (SAHA) in the 22Rv1 xenograft model. Results Using genetic and pharmacological approaches we demonstrated that a useful inhibition of AR transcriptional activity, absent the induction of EMT, could be achieved by specifically inhibiting HDAC3. Significantly, we also determined that HDAC3 inhibitors blocked the activity of the constitutively active AR V7-splice variant and inhibited the growth of xenograft tumors expressing this protein. Conclusions Our studies provide strong rationale for the near-term development of specific HDAC3 inhibitors for the treatment of CRPC.

Correlations of SELENOF and SELENOP genotypes with serum selenium levels and prostate cancer


Background Selenium status is inversely associated with the incidence of prostate cancer. However, supplementation trials have not indicated a benefit of selenium supplementation in reducing cancer risk. Polymorphisms in the gene encoding selenoprotein 15 (SELENOF) are associated with cancer incidence/mortality and present disproportionately in African Americans. Relationships among the genotype of selenoproteins implicated in increased cancer risk, selenium status, and race with prostate cancer were investigated. Methods Tissue microarrays were used to assess SELENOF levels and cellular location in prostatic tissue. Sera and DNA from participants of the Chicago-based Adiposity Study Cohort were used to quantify selenium levels and genotype frequencies of the genes for SELENOF and the selenium-carrier protein selenoprotein P (SELENOP). Logistic regression models for dichotomous patient outcomes and regression models for continuous outcome were employed to identify both clinical, genetic, and biochemical characteristics that are associated with these outcomes. Results SELENOF is dramatically reduced in prostate cancer and lower in tumors derived from African American men as compared to tumors obtained from Caucasians. Differing frequency of SELENOF polymorphisms and lower selenium levels were observed in African Americans as compared to Caucasians. SELENOF genotypes were associated with higher histological tumor grade. A polymorphism in SELENOP was associated with recurrence and higher serum PSA. Conclusions These results indicate an interaction between selenium status and selenoprotein genotypes that may contribute to the disparity in prostate cancer incidence and outcome experienced by African Americans.

Histological and quantitative analyzes of the stromal and acinar components of normal human prostate zones


Background McNeal divided the human prostate into three major anatomical areas: the peripheral zone (PZ), the central zone (CZ), and the transition zone (TZ). Each of these areas is biologically and histologically distinct. The PZ and TZ have clinical significance and are associated with prostate cancer (PC) and benign prostatic hyperplasia (BPH), respectively. Therefore, the objective of the present study was to quantitatively and qualitatively analyze the parenchymal and stromal components that constitute the different prostate zones. Methods We assessed 19 samples from each prostate zone. The samples were obtained from necropsies of young people between 18 and 32 years of age with intact urogenital tracts. The samples were fixed in 4% buffered formalin and processed for paraffin embedding. Sections with a thickness of five micrometres were obtained from each sample. The sections were stained using histochemical and immunohistochemical techniques to identify the acinar and stromal components of each zone. Photomicrographs were obtained for morphometric analysis using an algorithm based on color segmentation. Data were analyzed using one-way analysis of variance (ANOVA) with the Bonferroni post-test. Differences with P < 0.05 were regarded as statistically significant. Results Collagen fibres were more numerous in the TZ (+40.26%; P = 0.0230) than in the PZ. Muscle fibres were also more numerous in the TZ (+47.05%; P = 0.0120) than in the PZ. Elastic system fibres in the TZ significantly differed from those in the PZ (+84.61%; P = 0.0012) and the CZ (+61.66%; P = 0.0074). Similarly, nerves in the PZ (−42.86%; P = 0.0107) significantly differed from nerves in the CZ. Epithelial height was lower in the TZ than in the PZ (−30.17%; P = 0.0034) and the CZ (−25.01%; P = 0.0330). Conclusion Our objective, quantitative data regarding the various elements that constitute the normal prostate stroma allowed us to reveal differences among prostate zones. This study established patterns for normal parameters and may be used for posterior comparisons in histopathological analysis.

Prostatectomy-based validation of combined urine and plasma test for predicting high grade prostate cancer


Background Distinguishing between low- and high-grade prostate cancers (PCa) is important, but biopsy may underestimate the actual grade of cancer. We have previously shown that urine/plasma-based prostate-specific biomarkers can predict high grade PCa. Our objective was to determine the accuracy of a test using cell-free RNA levels of biomarkers in predicting prostatectomy results. Methods This multicenter community-based prospective study was conducted using urine/blood samples collected from 306 patients. All recruited patients were treatment-naïve, without metastases, and had been biopsied, designated a Gleason Score (GS) based on biopsy, and assigned to prostatectomy prior to participation in the study. The primary outcome measure was the urine/plasma test accuracy in predicting high grade PCa on prostatectomy compared with biopsy findings. Sensitivity and specificity were calculated using standard formulas, while comparisons between groups were performed using the Wilcoxon Rank Sum, Kruskal-Wallis, Chi-Square, and Fisher's exact test. Results GS as assigned by standard 10-12 core biopsies was 3 + 3 in 90 (29.4%), 3 + 4 in 122 (39.8%), 4 + 3 in 50 (16.3%), and > 4 + 3 in 44 (14.4%) patients. The urine/plasma assay confirmed a previous validation and was highly accurate in predicting the presence of high-grade PCa (Gleason ≥3 + 4) with sensitivity between 88% and 95% as verified by prostatectomy findings. GS was upgraded after prostatectomy in 27% of patients and downgraded in 12% of patients. Conclusions This plasma/urine biomarker test accurately predicts high grade cancer as determined by prostatectomy with a sensitivity at 92-97%, while the sensitivity of core biopsies was 78%.

Analogous detection of circulating tumor cells using the AccuCyte®—CyteFinder® system and ISET system in patients with locally advanced and metastatic prostate cancer


Introduction Circulating tumor cells (CTCs) can provide important information on patient's prognosis and treatment efficacy. Currently, a plethora of methods is available for the detection of these rare cells. We compared the outcomes of two of those methods to enumerate and characterize CTCs in patients with locally advanced and metastatic prostate cancer (PCa). First, the selection-free AccuCyte® − CyteFinder® system (RareCyte®, Inc., Seattle, WA) and second, the ISET system (Rarecells Diagnostics, France), a CTC detection method based on cell size-exclusion. Methods Peripheral blood samples were obtained from 15 patients with metastatic PCa and processed in parallel, using both methods according to manufacturer's protocol. CTCs were identified by immunofluorescence, using commercially available antibodies to pancytokeratin (PanCK), EpCAM, CD45/CD66b/CD34/CD11b/CD14 (AccuCyte® − CyteFinder® system), and pancytokeratin, vimentin (Vim) and CD45 (ISET system). Results The median CTC count was 5 CTCs/7.5 mL (range, 0-20) for the AccuCyte® − CyteFinder® system and 37 CTCs/7.5 mL (range, 8-139) for the ISET system (P < 0.001). Total CTC counts obtained for the two methods were correlated (r = 0.750, P = 0.001). When separating the total CTC count obtained with the ISET system in PanCK+/Vim− and PanCK+/Vim+ CTCs, the total CTC count obtained with the AccuCyte® − CyteFinder® system was moderately correlated with the PanCK+/Vim− CTCs, and strongly correlated with the PanCK+/Vim+ CTCs (r = 0.700, P = 0.004 and r = 0.810, P < 0.001, respectively). Conclusion Our results highlight significant disparities in the enumeration and phenotype of CTCs detected by both techniques. Although the median amount of CTCs/7.5 mL differed significantly, total CTC counts of both methods were strongly correlated. For future studies, a more uniform approach to the isolation and definition of CTCs based on immunofluorescent stains is needed to provide reproducible results that can be correlated with clinical outcomes.

Effect of FAK inhibitor VS-6063 (defactinib) on docetaxel efficacy in prostate cancer


Background Docetaxel, the standard chemotherapy for metastatic castration-resistant prostate cancer (CRPC) also enhances the survival of patients with metastatic castration-sensitive prostate cancer (CSPC) when combined with androgen-deprivation therapy. Focal Adhesion Kinase (FAK) activation is a mediator of docetaxel resistance in prostate cancer cells. The aim of this study was to investigate the effect of the second generation FAK inhibitor VS-6063 on docetaxel efficacy in pre-clinical CRPC and CSPC models. Methods Docetaxel-resistant CRPC cells, mice with PC3 xenografts, and ex vivo cultures of patient-derived primary prostate tumors were treated with VS-6063 and/or docetaxel, or vehicle control. Cell counting, immunoblotting, and immunohistochemistry techniques were used to evaluate the treatment effects. Results Docetaxel and VS-6063 co-treatment caused a greater decrease in the viability of docetaxel-resistant CRPC cells, and a greater inhibition in PC3 xenograft growth compared to either monotherapy. FAK expression in human primary prostate cancer was positively associated with advanced tumor stage. Patient-derived prostate tumor explants cultured with both docetaxel and VS-6063 displayed a higher percentage of apoptosis in cancer cells, than monotherapy treatment. Conclusions Our findings suggest that co-administration of the FAK inhibitor, VS-6063, with docetaxel represents a potential therapeutic strategy to overcome docetaxel resistance in prostate cancer.