Role In Prostate Cancer Progression Research Articles

Abstract 525: Role of a novel microRNA gene at frequently deleted chromosome 8p region in prostate cancer

Abstract A frequent alteration in the prostate oncogenome is the loss of chromosome (chr) 8p21-22 region that has been traditionally associated with the loss of homeodomain protein, NKX3.1, that plays important roles in prostate cancer (PCa) initiation. Genomic deletions of this region increase significantly with tumor grade and are associated with poor prognosis in prostate cancer suggesting a link of this region with PCa progression. We proposed and validated a novel, paradigm shifting hypothesis that this frequently deleted locus is associated with a cluster of miRNA genes - miR-3622a/b and miR-383- that are lost in PCa and play an important mechanistic role in PCa progression and metastasis by regulating Epithelial-mesenchymal transition (EMT) and stemness. Extending our hypothesis, in this study, we evaluated the role of another miRNA gene located within this region- miR-4288- in prostate cancer. To understand the role of miR-4288 in prostate cancer, we performed miRNA expression profiling in laser capture microdissected (LCM) PCa tissues (n=64) and matched adjacent normal regions by real-time PCR. miR-4288 expression was down regulated in ~66% of tissue samples. miR-4288 expression was not altered significantly in 14% cases and high miR-4288 expression was observed in 20% cases. We performed ROC (Receiver Operating Characteristic) analyses to test the diagnostic potential of miR-4288 expression. Our analyses showed that miR-4288 expression can be a significant parameter to discriminate between normal and tumor tissues with an area under the ROC curve (AUC) of 0.711 (95% CI: 0.625-0.787, P<0.0001). We found that miR-4288 exhibits 81.54% sensitivity and 51% specificity as a diagnostic parameter. Association with clinicopathological parameters of the disease showed that miR-4288 expression was not significantly correlated with age, tumor stage, Gleason grade, biochemical recurrence or serum PSA levels. However, significant correlation was observed between miR-4288 expression and race. Analyses of miR-4288 expression in prostate cell lines showed that its expression is specifically attenuated in PCa cell lines compared to normal or immortalized prostate epithelial cells. To evaluate the functional role of miR-4288 in prostate cancer, miR-4288 precursor was overexpressed in PCa cell lines followed by functional assays. miR-4288 overexpression in PC3 and LNCaP cell lines led to decreased cellular viabilities as compared to control cells. Our preliminary data suggests that miR-4288 overexpression lead to morphological changes in these cell lines consistent with mesenchymal to epithelial transition (MET). In conclusion, our data suggests that miR-4288 is commonly downregulated in prostate cancer and plays an important regulatory role. Citation Format: Divya Bhagirath, Thao Yang, Shahana Majid, Varahram Shahryari, Soichiro Yamamura, Z. Laura Tabatabai, Rajvir Dahiya, Guoren Deng, Sharanjot Saini. Role of a novel microRNA gene at frequently deleted chromosome 8p region in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 525.

Abstract 4373: AR signaling in concert with PP2A/B regulates YAP1 expression in prostate cancer cells

Abstract The transcriptional coactivator YAP1 is a key nuclear effector of the Hippo pathway. STK4/MST1 and LATS1/2 are the core kinase components of the Hippo pathway, which restricts organ size and prevents tumorigenesis by attenuating cell proliferation and inducing cell death. Previously, we have reported that STK4/Hippo-YAP1 signaling could play a critical role in prostate cancer progression and therapeutic relapse. Here, we investigated the effects of androgen hormone signaling on YAP1 expression and post-transcriptional modifications in prostate cancer cells. We demonstrated that androgen exposure reduced Ser127 phosphorylation on YAP1 in a time-dependent manner in the castration-sensitive prostate cancer cell line, LNCaP, but without altering the levels of YAP1-Ser127 phosphorylation in the C4-2 cell line, a castration-resistant subline of LNCaP cells. As demonstrated by imaging and cell fractionation methods, androgen exposure promoted the nuclear accumulation of YAP1 in LNCaP; however, regardless of androgen exposure, YAP1 was accumulated in the nucleus of C4-2 cells. In addition, we demonstrated that androgen exposure reduced YAP1-Ser127 phosphorylation that was induced by okadaic acid, a potent activator of Ser/Thr phosphatases PP1 and PP2A. Also, we demonstrated that androgen exposure increased PP2A/B protein expression. Moreover, reduction of phospho-Ser127-YAP1 was correlated with increases in total YAP1 protein, which coincided with androgen receptor (AR) nuclear accumulation by androgen. Consistent with these observation, the genetic (siRNA) or the pharmacologic (enzalutamide) inhibition of AR signaling attenuated the expression of YAP1 protein. Furthermore, our analysis of the publicly available TCGA (The Cancer Genome Atlas) set indicated that YAP1 and AR mRNA expressions were positively correlated in prostate clinical samples. These observations suggest that YAP1 is a direct target of androgen hormone signaling, implicating that the AR-PP2A/B-YAP1 axis is a viable cancer drug target. Citation Format: Bekir Cinar, Carlos S. Moreno. AR signaling in concert with PP2A/B regulates YAP1 expression in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4373.

Abstract 2637: Expression of SALL4 in prostate cancer

Abstract Few prognostic biomarkers for Prostate cancer have been identified and there are clinical difficulties in distinguishing between relapsing and non-relapsing disease. The aim of our study is to investigate the hypothesis that proteins that have been linked to stem cells might be potential biomarkers, that could distinguish between aggressive tumors requiring radical intervention and those that have a good prognosis. One of the potential biomarkers that are being investigated is Sall4, a zinc finger transcriptional factor which has an important role in stem cell development and oncogeneses, including a possible role in prostate cancer progression and relapse. However, its role in prostate cancer remains unclear. Sall4 nuclear staining has been evaluated by immunohistochemistry using two sources of patient samples, a tissue microarray group and a Bath cohort. The tissue microarray group consists of 96 cases including normal prostate, adjacent normal prostate, and prostate cancer samples. The Bath cohort consists of 22 samples, including samples from patients that had recurrent disease and those who remained disease free. Sall4 nuclear staining was found to be decreased in prostate cancer samples compared to benign tissue from the tissue microarray group. Sall4 nuclear staining was also negatively associated with poorly differentiated grades of prostate cancer in the tissue microarray group. The Bath cohort did not have enough benign tissues to confirm the relationship between cancer and benign tissues but showed a negative association with the grade. Sall4 nuclear staining in tissue from both sets of samples was not associated with prostate cancer stages. It can be seen from this preliminary data that Sall4 might play an important role in tumor formation and/or aggressiveness and warrants further investigation to understand its function and establish if it could represent a potential diagnostic biomarker for prostate cancer. Citation Format: Dhafer A. Alghezi, Paul Whitley, Mark Beresford, Rebecca Bowen, John Mitchard, Andrew Chalmers. Expression of SALL4 in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2637.

Abstract 5107: A novel MTA1 knock-in mouse model for the mechanistic and therapeutic studies of MTA1-driven prostate cancer

Abstract Metastasis-associated protein 1 is known to play role in prostate cancer progression and metastasis. Studies of MTA1-mediated prostate cancer tumorigenesis, progression and metastasis have been hampered by a lack of suitable experimental system. Here we describe a new conditional mouse model that shows strong MTA1 expression in the prostate. This model was generated through MTA1 transgene knocked into the mouse ROSA26 (R26) locus using CAG-LoxP-Stop-LoxP (LSL)-2HA-MTA1-T2A-GFP-pA construct (Applied StemCell,Inc, Menlo Park, CA). Briefly, after generation of a genetically modified founder mouse line Rosa26-3attP, resulted MTA1 transgene embryos were injected into foster mice to produce MTA1 founders, designated as R26-LSL-MTA1. To monitor tumor formation and development in live animals by using IVIS, we have crossbred R26-LSL-MTA1 with Pb-Cre+;Luc and generated transgenic lines that express MTA1 and Luc upon Cre-mediated removal of the LSL cassette, specifically in the prostate epithelium (Pb-Cre+;R26MTA1;R26Luc) (MTA1-tg). We confirmed prostate-specific expression of the MTA1 transgene on mRNA and protein levels. We evaluated prostate histology for differences in histology of control normal prostates (Pb-Cre-; MTA1-tg) and MTA1-tg mice at as early as 13-weeks of age. MTA1 overexpressing prostate showed signs of mPIN characterized by glandular structures composed of atypical proliferating luminal cells that fill out the lumen. We detected differences in cellular proliferation, as determined by increased PCNA and decreased p27 as well as Ki67 immunofluorescent staining in MTA1-tg prostate. Moreover, expression of several oncogenic MTA1-guided molecules was increased in the prostates of MTA1-tg mice. We have previously reported on the role of MTA1-mediated signaling in prostate tumor progression in the prostate-specific Pten heterozygous (Pb-Cre+; Pten+/f) and Pten null (Pb-Cre+; Ptenf/f ) mice. To determine the role of MTA1 overexpression in the context of PTEN loss, we generated MTA1-tg; Pten+/f and MTA1-tg; Ptenf/f mice to evaluate whether MTA1overexpression in the prostate promotes an earlier onset, greater total incidence, accelerated tumor growth rate and metastasis. We predict that MTA1 overexpression will cause higher activation of downstream pathways to promote cancer cell survival, which will result in increased incidence of invasive adenocarcinoma and probably lymph node metastasis. Mice will be sacrificed at different time points for prostate tissue and lymph nodes isolation and subsequent histopathological, immunochemical and molecular evaluation. Citation Format: Avinash Kumar, Swati Dhar, Nasir A. Butt, Pravin R. Phadatare, Kshiti Dholakia, Jogarao Vedula, Virginia Donovan, Anait S. Levenson. A novel MTA1 knock-in mouse model for the mechanistic and therapeutic studies of MTA1-driven prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5107.

Quantitative Proteomics of TRAMP Mice Combined with Bioinformatics Analysis Reveals That PDGF-B Regulatory Network Plays a Key Role in Prostate Cancer Progression.

Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice is a widely used transgenic animal model of prostate cancer (PCa). We performed a label-free quantitative proteomics analysis combined with a bioinformatics analysis on the entire prostate protein extraction from TRAMP mice and compared it with WT littermates. From 2379 total identified proteins, we presented a modest mice prostate reference proteome containing 919 proteins. 61 proteins presented a significant expression difference between two groups. The integrative bioinformatics analysis predicted the overexpression of platelet-derived growth factor B (PDGF-B) in tumor tissues and supports the hypothesis of the PDGF-B signaling network as a key upstream regulator in PCa progression. Furthermore, we demonstrated that Crenolanib, a novel PDGF receptor inhibitor, inhibited PCa cell proliferation in a dose-dependent manner. Finally, we revealed the importance of PDGF-B regulatory network in PCa progression, which will assist us in understanding the role and mechanisms of PDGF-B in promoting cancer growth and provide valuable knowledge for future research on anti-PDGF therapy.

Autophagy induced by overexpression of DCTPP1 promotes tumor progression and predicts poor clinical outcome in prostate cancer

Although dCTP pyrophosphatase 1 (DCTPP1) has been reported to be associated with poor clinical outcomes in various cancers, whether it plays an important role in prostate cancer (PCa) remains unclear. In this study, an immunohistochemical assay showed the protein expression level of DCTPP1 was significantly higher in PCa tissues than in non-cancerous tissues. Moreover, DCTPP1 was upregulated at both protein and mRNA levels in the PCa tissues from high Gleason score patients versus low Gleason score patients. The analysis of The Cancer Genome Atlas RNA-seq data suggested that upregulation of DCTPP1 was inversely correlated with biochemical recurrence free survival and overall survival. The roles of DCTPP1 in tumor progression and autophagy were further validated through cells invasion, migration, apoptosis and proliferation assays in vitro, as well as EMT and autophagy assays in vivo. Advanced bioinformatics analysis identified the evidence supporting the promotional role of DCTPP1 in tumor progression associated with autophagy. We conclude that DCTPP1 may play an important role in PCa progression associated with high autophagy. Overexpression of DCTPP1 may server as a biomarker for predicting poor BCR-free survival and overall survival for PCa patients.

Transcriptional and post-transcriptional regulation of ribonucleotide reductase (RRM2) control its oncogenic role in prostate cancer progression.

5044Background: The role of DNA repair pathways has been recognized in prostate cancer (PC) progression. Ribonucleotide reductase (RNR) is essential for DNA synthesis and repair. The subunit of RNR...

ONC201 Targets AR and AR-V7 Signaling, Reduces PSA, and Synergizes with Everolimus in Prostate Cancer.

Androgen receptor (AR) signaling plays a key role in prostate cancer progression, and androgen deprivation therapy (ADT) is a mainstay clinical treatment regimen for patients with advanced disease. Unfortunately, most prostate cancers eventually become androgen-independent and resistant to ADT with patients progressing to metastatic castration-resistant prostate cancer (mCRPC). Constitutively activated AR variants (AR-V) have emerged as mediators of resistance to AR-targeted therapy and the progression of mCRPC, and they represent an important therapeutic target. Out of at least 15 AR-Vs described thus far, AR-V7 is the most abundant, and its expression correlates with ADT resistance. ONC201/TIC10 is the founding member of the imipridone class of small molecules and has shown anticancer activity in a broad range of tumor types. ONC201 is currently being tested in phase I/II clinical trials for advanced solid tumors, including mCRPC, and hematologic malignancies. There has been promising activity observed in patients in early clinical testing. This study demonstrates preclinical single-agent efficacy of ONC201 using in vitro and in vivo models of prostate cancer. ONC201 has potent antiproliferative and proapoptotic effects in both castration-resistant and -sensitive prostate cancer cells. Furthermore, the data demonstrate that ONC201 downregulates the expression of key drivers of prostate cancer such as AR-V7 and downstream target genes including the clinically used biomarker PSA (KLK3). Finally, the data also provide a preclinical rationale for combination of ONC201 with approved therapeutics for prostate cancer such as enzalutamide, everolimus (mTOR inhibitor), or docetaxel.Implications: The preclinical efficacy of ONC201 as a single agent or in combination, in hormone-sensitive or castration-resistant prostate cancer, suggests the potential for immediate clinical translation. Mol Cancer Res; 16(5); 754-66. ©2018 AACR.

Expression and role of PAICS, a de novo purine biosynthetic gene in prostate cancer.

BACKGROUND Our goal was to investigate de novo purine biosynthetic gene PAICS expression and evaluate its role in prostate cancer progression. METHODS Next-generation sequencing, qRTPCR and immunoblot analysis revealed an elevated expression of a de novo purine biosynthetic gene, Phosphoribosylaminoimidazole Carboxylase, Phosphoribosylaminoimidazole Succinocarboxamide Synthetase (PAICS) in a progressive manner in prostate cancer. Functional analyses were performed using prostate cancer cell lines- DU145, PC3, LnCaP, and VCaP. The oncogenic properties of PAICS were studied both by transient and stable knockdown strategies, in vivo chicken chorioallantoic membrane (CAM) and murine xenograft models. Effect of BET bromodomain inhibitor JQ1 on the expression level of PAICS was also studied. RESULTS Molecular staging of prostate cancer is important factor in effective diagnosis, prognosis and therapy. In this study, we identified a de novo purine biosynthetic gene; PAICS is overexpressed in PCa and its expression correlated with disease aggressiveness. Through several in vitro and in vivo functional studies, we show that PAICS is necessary for proliferation and invasion in prostate cancer cells. We identified JQ1, a BET bromodomain inhibitor previously implicated in regulating MYC expression and demonstrated role in prostate cancer, abrogates PAICS expression in several prostate cancer cells. Furthermore, we observe loss of MYC occupancy on PAICS promoter in presence of JQ1. CONCLUSIONS Here, we report that evaluation of PAICS in prostate cancer progression and its role in prostate cancer cell proliferation and invasion and suggest it as a valid therapeutic target. We suggest JQ1, a BET-domain inhibitor, as possible therapeutic option in targeting PAICS in prostate cancer. Prostate. © 2016 Wiley Periodicals, Inc.

Increased KIF4A expression is a potential prognostic factor in prostate cancer.

The kinesin super-family protein (KIF) 4A gene is reported to be overexpressed and associated with poor clinical prognosis in human cancers; however, its clinical significance in prostate cancer (PCa) has not been well studied. The present study performed dataset analyses and revealed that KIF4A expression was significantly increased in castration-resistant PCa patients. Additionally, KIF4A expression was significantly highly expressed in PCa tissues compared with non-cancerous tissues, particularly in advanced PCa pathological stages. Upregulated KIF4A mRNA expression in PCa tissues was significantly correlated with shorter overall survival and prostate-specific antigen failure. Furthermore, both univariate and multivariate analyses revealed that upregulated KIF4A may predict poor biochemical recurrence (BCR)-free survival. The data suggested that KIF4A may play a key role in PCa progression. Notably, increased KIF4A expression may potentially predict poor BCR-free survival in PCa patients.

MiR-221-5p enhances cell proliferation and metastasis through post-transcriptional regulation of SOCS1 in human prostate cancer

BackgroundTo investigate the effect of miR-221-5p on cell proliferaton and metastasis of human prostate cancer in vitro and vivo.MethodsWe established PC3 cell lines with stable overexpression or silencing of miRNA-221-5p via lentivirus infection. miRNA-221-5p and its target gene SOCS1 expression levels in the stable cells were analyzed by real-time polymerase chain reaction (RT-PCR) and western blotting. Using luciferase reporter assays to study the relationship between miR-221-5p and SOCS1. Cell proliferative activity was measured using the MTT assay and colony formation assay. Migration ability was assessed using wound-healing assay and transwell assay. To further study the function of miR-221-5p in human prostate cancer we established nude mice xenograft model in vivo.ResultsmiR-221-5p regulates the proliferation, migration of prostate cancer cells in vitro and tumorigenesis in vivo by regulating socs1 expression through targeted its 3’UTR, and miR-221-5p regulates MAPK/ERK signaling pathway and EMT features in prostate cancer cells.ConclusionsUp-regulation and silencing of miR-221-5p expression in prostate cancer cells are correlated with cell proliferation, migration and tumorigenesis, which suggest that miR-221-5p plays an important role in prostate cancer progression.

LXRs, SHP, and FXR in Prostate Cancer: Enemies or Ménage à Quatre With AR?

Androgens and androgen receptor (AR, NR3C4) clearly play a crucial role in prostate cancer progression. Besides, the link between metabolic disorders and the risk of developing a prostate cancer has been emerging these last years. Interestingly, “lipid” nuclear receptors such as LXRα/NR1H3 and LXRβ/NR1H2 (as well as FXRα/NR1H4 and SHP/NR0B2) have been described to decrease the lipid metabolism, while AR increases it. Moreover, these former orphan nuclear receptors can regulate androgen levels and modulate AR activity. Thus, it is not surprising to find such receptors involved in the physiology of prostate. This review is focused on the roles of liver X receptors (LXRs), farnesoid X receptor (FXR), and small heterodimeric partner (SHP) in prostate physiology and their capabilities to interfere with the androgen-regulated pathways by modulating the levels of active androgen within the prostate. By the use of prostate cancer cell lines, mice deficient for these nuclear receptors and human tissue libraries, several authors have pointed out the putative possibility to pharmacologically target these receptors. These data open a new field of research for the development of new drugs that could overcome the castration resistance in prostate cancer, a usual phenomenon in patients.

Genomic Gain of 16p13.3 in Prostate Cancer Predicts Poor Clinical Outcome after Surgical Intervention

Identifying tumors with high metastatic potential is key to improving the clinical management of prostate cancer. Recently, we characterized a chromosome 16p13.3 gain frequently observed in prostate cancer metastases and now demonstrate the prognostic value of this genomic alteration in surgically treated prostate cancer. Dual-color FISH was used to detect 16p13.3 gain on a human tissue microarray representing 304 primary radical prostatectomy (RP) cases with clinical follow-up data. The results were validated in an external dataset. The 16p13.3 gain was detected in 42% (113/267) of the specimens scorable by FISH and was significantly associated with clinicopathologic features of aggressive prostate cancer, including high preoperative PSA (P = 0.03) levels, high Gleason score (GS, P < 0.0001), advanced pathologic tumor stage (P < 0.0001), and positive surgical margins (P = 0.009). The 16p13.3 gain predicted biochemical recurrence (BCR) in the overall cohort (log-rank P = 0.0005), and in subsets of patients with PSA ≤10 or GS ≤7 (log-rank P = 0.02 and P = 0.006, respectively). Moreover, combining the 16p13.3 gain status with standard prognostic markers improved BCR risk stratification and identified a subgroup of patients with high probability of recurrence. The 16p13.3 gain status was also associated with an increased risk of developing distant metastases (log-rank P = 0.03) further substantiating its role in prostate cancer progression.Implications: This study demonstrates the prognostic significance of the 16p13.3 genomic gain in primary prostate tumors, suggesting potential utility in the clinical management of the disease by identifying patients at high risk of recurrence who may benefit from adjuvant therapies. Mol Cancer Res; 16(1); 115-23. ©2017 AACR.

Phosphoglycerate mutase 1 knockdown inhibits prostate cancer cell growth, migration, and invasion.

Phosphoglycerate mutase 1 (PGAM1) is upregulated in many cancer types and involved in cell proliferation, migration, invasion, and apoptosis. However, the relationship between PGAM1 and prostate cancer is poorly understood. The present study investigated the changes in PGAM1 expression in prostate cancer tissues compared with normal prostate tissues and examined the cellular function of PGAM1 and its relationship with clinicopathological variables. Immunohistochemistry and Western blotting revealed that PGAM1 expression was upregulated in prostate cancer tissues and cell lines. PGAM1 expression was associated with Gleason score (P = 0.01) and T-stage (P = 0.009). Knockdown of PGAM1 by siRNA in PC-3 and 22Rv1 prostate cancer cell lines inhibited cell proliferation, migration, and invasion and enhanced cancer cell apoptosis. In a nude mouse xenograft model, PGAM1 knockdown markedly suppressed tumor growth. Deletion of PGAM1 resulted in decreased expression of Bcl-2, enhanced expression of Bax, caspases-3 and inhibition of MMP-2 and MMP-9 expression. Our results indicate that PGAM1 may play an important role in prostate cancer progression and aggressiveness, and that it might be a valuable marker of poor prognosis and a potential therapeutic target for prostate cancer.

The dark side of glucose transporters in prostate cancer: Are they a new feature to characterize carcinomas?

One of the hallmarks of cancer cells is the increased ability to acquire nutrients, particularly glucose and glutamine. Proliferating cells need precursors for cell growth and NADPH reducing equivalents for survival. The principal responsible for glucose uptake is facilitative glucose transporters (GLUTs), which usually are overexpressed in cancer cells. Besides their role in glucose uptake, GLUT transporters are able to transport other compounds such as dehydroascorbic acid or uric acid. They play a major role in tumor progression and cellular processes such as regulated cell death. The prostate gland has the particular characteristic of being more glycolytic than other non-pathological tissues given an accumulation of citrate in the seminal fluid and the inhibition of m-aconitase that affects to tricarboxylic acid cycle. In prostate cancer (PCa), androgens increase glucose uptake, upregulate GLUT transporters such as GLUT1 and GLUT3 and stimulate AMP-activated protein kinase pathway, suggesting a possible connection between glycolytic and androgenic signaling. Interestingly, diabetes is not a risk factor for PCa, as it is in other cancers, while insulin stimulates progression and insulin-like growth factor 1 pathway plays an important role in PCa progression. It was recently found that PCa cells overexpress GLUT4 and, more importantly, that it seems to be related to the castration-resistant prostate cancer (CRPC) phenotype, although little is known about its participation in tumor progression. This review will focus on the role of GLUT transporters along with PCa progression, and the involvement of GLUT4 on CRPC phenotype transition would be considered.

Dimethylarginine dimethylaminohydrolase-1 (DDAH1) is frequently upregulated in prostate cancer, and its overexpression conveys tumor growth and angiogenesis by metabolizing asymmetric dimethylarginine (ADMA).

Tissue microarray analysis confirmed higher dimethylarginine dimethylaminohydrolase-1 (DDAH1) expression in prostate cancer (PCa) compared to benign and normal prostate tissues. DDAH1 regulates nitric oxide (NO) production by degrading endogenous nitric oxide synthase (NOS) inhibitor, asymmetric dimethylarginine (ADMA). This study examined whether DDAH1 has any physiological role in PCa progression. Using overexpression of DDAH1 in PCa (PC3 and LNCaP) cell lines, we found that DDAH1 promotes cell proliferation, migration and invasion by lowering ADMA levels, as well as increasing NO production. VEGF, HIF-1α and iNOS were upregulated in DDAH1 expressing cells as result of elevated NO. DDAH1 increased secretion of pro-angiogenic signals bFGF and IL-8, into conditioned media. Treatment of DDAH1-positive PCa cells with NOS inhibitors (L-NAME and 1400W) attenuated DDAH1 activity to promote cell growth. Xenografts derived from these cells grew significantly faster (>twofold) than those derived from control cells. Proliferation rate of cells stably expressing mutant DDAH1 was same as control cells unlike wild-type DDAH1-positive PCa cells. Xenograft tumors derived from mutant-positive cells did not differ from control tumors. VEGF, HIF-1α and iNOS expression did not differ in DDAH1 mutant-positive tumors compared to control tumors, but was upregulated in wild-type DDAH1 overexpressing tumors. Furthermore, CD31 immunostaining on xenograft tissues demonstrated that DDAH1 tumors had high endothelial content than mutant DDAH1 tumors. These data suggest that DDAH1 is an important mediator of PCa progression and NO/DDAH pathway needs to be considered in developing therapeutic strategies targeted at PCa.

GLUT1 regulates cell glycolysis and proliferation in prostate cancer.

Glucose transporter 1 (GLUT1) plays a critical role in tumorigenesis and tumor progression in multiple cancer types. However, the specific function and clinical significance of GLUT1 in prostate cancer (PCa) are still unclear. Therefore, in this study, we investigated the role of GLUT1 in PCa. GLUT1 protein levels in prostate cancer tissue and tumor-adjacent normal tissues were measured and compared. Furthermore, real-time PCR and Western blot analysis were both used to detect GLUT1 expression levels in different PCa cell lines. Flow cytometry and cell-based assays, such as a glucose uptake and lactate secretion assay, CCK-8 assay, and transwell migration and wound healing assay, were used to monitor cancer cell cycle distribution, glycolysis, proliferation, and motility, respectively. Moreover, a mouse tumor xenograft model was used to investigate the role of GLUT1 in tumor progression in vivo. GLUT1 expression levels are higher in PCa tissues than in tumor-adjacent normal tissues. The results from real-time PCR and Western blot analysis revealed a similar increase in the GLUT1 expression levels in PCa cell lines. Moreover, knockdown of GLUT1 inhibits cell glycolysis and proliferation and leads to cell cycle arrest at G2/M phase in the 22RV1 cell line but not in the PC3 cell line. In vivo experiments further confirmed that GLUT1 knockdown inhibits the growth of tumors derived from the 22RV1 cell line. In addition, we also showed that GLUT1 knockdown has no effect on cell migration in vitro. GLUT1 may play an important role in PCa progression via mediating glycolysis and proliferation. Our study also indicated a potential crosstalk between GLUT1-mediated glycolysis and androgen sensitivity in PCa.

Tenascin-C and Integrin α9 Mediate Interactions of Prostate Cancer with the Bone Microenvironment.

Deposition of the extracellular matrix protein tenascin-C is part of the reactive stroma response, which has a critical role in prostate cancer progression. Here, we report that tenascin C is expressed in the bone endosteum and is associated with formation of prostate bone metastases. Metastatic cells cultured on osteo-mimetic surfaces coated with tenascin C exhibited enhanced adhesion and colony formation as mediated by integrin α9β1. In addition, metastatic cells preferentially migrated and colonized tenascin-C-coated trabecular bone xenografts in a novel system that employed chorioallantoic membranes of fertilized chicken eggs as host. Overall, our studies deepen knowledge about reactive stroma responses in the bone endosteum that accompany prostate cancer metastasis to trabecular bone, with potential implications to therapeutically target this process in patients. Cancer Res; 77(21); 5977-88. ©2017 AACR.

A regulatory circuit HP1γ/miR-451a/c-Myc promotes prostate cancer progression.

Heterochromatin protein 1γ (HP1γ) has been implicated in carcinogenesis of various cancer types. However, the role of HP1γ in prostate cancer (PCa) progression and the underlying molecular mechanisms remain largely unknown. We found that HP1γ is upregulated in PCa and elevated levels of HP1γ in PCa predict poor outcome. In addition, depletion of HP1γ in PCa cells not only repressed proliferation and induced apoptosis but also impaired tumorigenicity. We also found that c-Myc was capable of upregulating HP1γ by directly binding to the E-box element in the first intron of HP1γ gene, and the upregulated HP1γ, in turn, repressed the expression of miR-451a by enhancing H3K9 methylation at the promoter region of miR-451a. Furthermore, reduction of miR-451a significantly reversed HP1γ loss-induced PCa cell apoptosis, whereas miR-451a overexpression repressed cell survival by targeting and downregulating c-Myc. The association among c-Myc, HP1γ and miR-451a was further confirmed in human clinical samples. Therefore, we propose that an HP1γ/miR-451a/c-Myc regulatory circuitry exists in PCa cells and this circuit has a crucial role in PCa progression.

Cytotoxic necrotizing factor 1 promotes prostate cancer progression through activating the Cdc42-PAK1 axis.

Uropathogenic Escherichia coli (UPEC) is the leading cause of urinary tract infections and plays a role in prostatic carcinogenesis and prostate cancer (PCa) progression. However, the mechanisms through which UPEC promotes PCa development and progression are unclear. Cytotoxic necrotizing factor 1 (CNF1) is one of the most important UPEC toxins and its role in PCa progression has never been studied. We found that UPEC-secreted CNF1 promoted the migration and invasion of PCa cells and PCa metastasis. In vitro studies showed that CNF1 promotes pro-migratory and pro-invasive activity through entering PCa cells and activating Cdc42, which subsequently induced PAK1 phosphorylation and up-regulation of MMP-9 expression. CNF1 also promoted pulmonary metastasis in a xenograft mouse model through these mechanisms. PAK1 phosphorylation correlated with advanced grades of PCa in human clinical PCa tissues. These results suggest that CNF1 derived from UPEC plays an important role in PCa progression through activating a Cdc42-PAK1 signal axis and up-regulating the expression of MMP-9. Therefore, surveillance for and treatment of cnf1-carrying UPEC strains may diminish PCa progression and thus have an important clinical therapeutic impact. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.