Function In Prostate Cancer Cells Research Articles

Enzalutamide-resistant related lncRNA NONHSAT210528 promotes the proliferation and invasion of prostate cancer.

BackgroundAs a new-generation androgen-receptor antagonist, enzalutamide is a first-choice drug for advanced prostate cancer (PCa) patients. However, secondary resistance to enzalutamide poses a new challenge in the treatment of cancer. Long non-coding RNA (lncRNA) regulates cell function through many levels and mechanisms, and also plays an important role in the biological behaviors of tumors.MethodsLncRNA microarrays were used to detect enzalutamide-resistant related lncRNA in Enzalutamide-resistant C4-2 (C4-2 ENZ-R) cells and corresponding parent cells. Cell Counting Kit 8, flow cytometry, and transwell assays were used to test the effect of lncRNA NONHSAT210528 on the function of PCa cells. RNA pulls down and the luciferase report gene was used to detect the competitive endogenous RNA (ceRNA) mechanism. The culture supernatant of C4-2 and C4-2b cells was transferred to the lower chamber for transwell assay of human umbilical endothelial cells (HUVECs).ResultsThe lncRNA microarray analysis showed that there were significant differences in the expression of many lncRNAs between the C4-2 ENZ-R and C4-2 cells. The real-time polymerase chain reaction (PCR) detection showed that the expression of lncRNA NONHSAT210528 was significantly higher in the C4-2 ENZ-R cells than the C4-2 cells. The Transwell assays showed that lncRNA NONHSAT210528 overexpression increased the invasion of the C4-2 and C4-2b cells. The cell-wound scratch and the transwell assays showed that the culture supernatant of C4-2 and C4-2b cells with overexpressed lncRNA NONHSAT210528 promoted the migration and invasion of HUVECs. Furthermore, lncRNA NONHSAT210528 regulated the expression of YOD1 dependent on miR-21.ConclusionsEnzalutamide-resistant related lncRNA NONHSAT210528 appears to promote the proliferation and invasion of PCa cells by functioning as a ceRNA and regulating the miR-21-5p/YOD1 signal pathway.

TBX1 Functions as a Tumor Activator in Prostate Cancer by Promoting Ribosome RNA Gene Transcription.

TBX1 belongs to an evolutionarily conserved family of transcription factors involved in organ development. TBX1 has been reported to have a hypermethylated cytosine guanine dinucleotide island around its second exon, which was related to prostate cancer (PCa) progression. However, the role and exact mechanism of TBX1 in PCa remains unknown. Using human prostate samples, online data mining and multiple in vitro and in vivo models, we examined the biological role and underlying mechanisms of TBX1 in PCa. TBX1 was highly expressed in PCa tissues, and high TBX1 expression was positively associated with Gleason score, pathological tumor stage, pathological lymph node stage, extraprostatic extension and disease/progression-free survival. In vitro and in vivo data demonstrated that TBX1 silencing inhibits PCa cell proliferation and colony formation and increases the cell population at the G0/G1 phase. The exogenous expression of TBX1 rescued these phenotypes. Mechanistically, TBX1 silencing suppressed the expression of 45S ribosomal RNA (rRNA), which was rescued by the exogenous expression of TBX1. TBX1 silencing inhibited the monomethylation of histone 3 lysine 4 (H3K4me1) binding with the non-coding intergenic spacer (IGS) regions of ribosomal DNA (rDNA) and the recruitment of upstream binding factor to the promoter and IGS regions of rDNA. The drug-induced enhancement of H3K4me1 counteracted the effect of TBX1 silencing. These findings indicate that TBX1 exerts its tumor activator function in PCa cells via epigenetic control, thereby promoting rRNA gene transcription. Thus, TBX1 may represent a prognostic biomarker and therapeutic target for PCa patients.

Muscleblind-like 1 antisense RNA 1 inhibits cell proliferation, invasion, and migration of prostate cancer by sponging miR-181a-5p and regulating PTEN/PI3K/AKT/mTOR signaling

ABSTRACT The present study aimed to investigate the role and underlying mechanisms of long non-coding RNA (lncRNA) muscleblind-like 1 antisense RNA 1 (MBNL1-AS1) in the progression of Prostate cancer (PCa). MBNL1-AS1 and microRNA (miR)-181a-5p expression in PCa tissues and several human PCa cell lines were analyzed, respectively, using StarBasev3.0 project and RT-qPCR assay. After MBNL1-AS1 overexpression, cell proliferation, invasion and migration were, respectively, evaluated using CCK-8, colony formation, transwell and wound healing assays. Dual luciferase assay were used for analysis of the interactions among MBNL1-AS1, miR-181a-5p, and phosphatase and tensin homolog (PTEN). Subsequently, the expression of PTEN and proteins in PI3K/AKT/mTOR signaling was examined using western blot analysis after transfection with miR-181a-5p mimic. The rescue assays were performed to investigate the effects of MBNL1-AS1 and miR-181a-5p on the functions of PCa cells and the expression of PTEN/PI3K/AKT/mTOR signaling by co-transfection with MBNL1-AS1 plasmid and miR-181a-5p mimic. Results indicated that MBNL1-AS1 was conspicuously downregulated while miR-181a-5p upregulating in PCa tissues and cell lines. MBNL1-AS1 overexpression decreased the abilities of cell proliferation, invasion, and migration. Further study revealed that MBNL1-AS1 acted as a sponge for miR-181a-5p and positively regulated PTEN by a sponge effect. Additionally, rescue assays proved that the effect of MBNL1-AS1-upregulation on the proliferation, invasion, and migration of PCa cells was dependent on miR-181a-5p. Furthermore, miR-181a-5p overexpression counteracted the expression of PTEN and proteins in PI3K/AKT/mTOR signaling exerted by MBNL1-AS1-upregulation in PCa cells. This study suggests that MBNL1-AS1 inhibits the progression of PCa via sponging miR-181a-5p and regulating PTEN/PI3K/AKT/mTOR pathway.

MicroRNA‑16‑5p regulates cell survival, cell cycle and apoptosis by targeting AKT3 in prostate cancer cells.

Prostate cancer (PCa) is a malignancy with the highest morbidity rate in 105 countries worldwide and was a major cause of cancer‑associated death in men in 2018. Accumulating evidence suggests that microRNAs (miRNAs/miRs) have important functions in the carcinogenesis of PCa, and may provide novel treatment targets. Previous studies have indicated that miR‑16‑5p is associated with PCa. However, the relevance and importance of miR‑16‑5p in PCa carcinogenesis are still not completely understood. In the current study, we aimed to investigate the role and mechanism of miR‑16‑5p in PCa carcinogenesis. The results showed that miR‑16‑5p was markedly downregulated in PCa cells, and MTS assay, colony formation, flow cytometric analyses demonstrated that miR‑16‑5p inhibited PCa cell survival, regulated cell cycle distribution and induced apoptosis. Moreover, luciferase reporter assay and western blot analysis showed that miR‑16‑5p directly targets AKT3 (AKT serine/threonine kinase 3), which is associated with PCa carcinogenesis, and the effects of the downregulation of AKT3 were similar to the effects of upregulation of miR‑16‑5p in PC‑3 cells. In conclusion, our data clarify that miR‑16‑5p has anticancer functions in PCa cells, and our findings provide experimental evidence to highlight the potential value of miR‑targeting treatment strategies for PCa.

MiR-493 Induces Cytotoxic Autophagy in Prostate Cancer Cells through Regulation on PHLPP2

MiR-493 promotes the proliferation of prostate cancer (PC) cells by targeting PHLPP2. We aimed to explore the relationship between miR-493 and autophagy in PC. qRT-PCR and western blotting were used to determine the mRNA levels and protein expression of miR-493, PHLPP2, autophagy gene BECN1 and ATG7 in PC cells. The autophagy gene expression was determined after PC cells transfected with miR-493 precursor or PHLPP2 precursor. Corresponding changes of autophagy phenotype and PC cell function were also studied. The mRNA levels and protein expression of miR-493, PHLPP2, BECN1 and ATG7 in PC cells were significantly decreased in PC cells. Overexpression of miR-493 or PHLPP2 markedly upregulated the expression levels of BECN1 and ATG7 in PC cells. Overexpression of miR-493 and PHLPP2 markedly promoted autophagy, and inhibited the invasion and cloning formation of PC cells. MiR-493 is a potent inducer of cytotoxic autophagy that leads to prostate cancer inhibition by regulating on PHLPP2.

LncRNA PROX1-AS1 promotes proliferation, invasion, and migration in prostate cancer via targeting miR-647.

Long noncoding RNAs (lncRNAs) act as an important role in many diseases. In this research, lncRNA PROX1-AS1 was explored to identify how it functioned in the development of prostate cancer (PC). Real Time-quantitative Polymerase Chain Reaction (RT-qPCR) was utilized to detect PROX1-AS1 expression in PC patients. Then, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay, colony formation assay, and transwell assay were performed to identify its function in PC cells. Furthermore, the potential mechanism was also explored using mechanism assays. PROX1-AS1 expression level was significantly higher in PC tissue samples and cell lines. Results of MTT assay, colony formation assay, and transwell assay showed that cell proliferation and invasion were inhibited through the silence of PROX1-AS1 in PC cells, while cell proliferation and invasion were promoted through the overexpression of PROX1-AS1 in PC cells. Furthermore, the expression of miR-647 was upregulated via the silence of PROX1-AS1 in PC cells, while the expression of miR-647 was downregulated via the overexpression of PROX1-AS1 in PC cells. Further mechanism assays showed that miR-647 was a direct target of PROX1-AS1 in PC. Correlation analysis showed that miR-647 expression was negatively correlated with PROX1-AS1 expression in PC tissues. Results above suggested that PROX1-AS1 could enhance cell proliferation and invasion of PC cells by sponging miR-647 and might be applied as a novel target for the treatment of PC.

Elevated miR-615-3p Expression Predicts Adverse Clinical Outcome and Promotes Proliferation and Migration of Prostate Cancer Cells

miR-615-3p has previously been described as up-regulated in prostate cancer (PC) tissue samples compared with nonmalignant controls; however, its prognostic potential and functional role in PC remain largely unknown. In this study, we investigated the clinical and biological relevance of miR-615-3p in PC. The expression of miR-615-3p was measured in PC tissue specimens from 239 men who underwent radical prostatectomy (RP), and it was investigated if miR-615-3p could predict postoperative biochemical recurrence (BCR). These findings were subsequently validated in three independent RP cohorts (n = 222, n = 273, and n = 387) and functional overexpression studies conducted in PC cells (PC3M). High miR-615-3p expression was significantly associated with BCR in four independent PC patient cohorts (P<0.05, log-rank test). In addition, high miR-615-3p expression was a significant predictor of PC-specific survival in univariate (hazard ratio, 3.75; P<0.001) and multivariate (hazard ratio, 2.66; P=0.008) analysis after adjustment for the Cancer of the Prostate Risk Assessment Post-Surgical (CAPRA-S) nomogram in a merged RP cohort (n = 734). Moreover, overexpression of miR-615-3p in PC cells (PC3M) significantly increased cell viability, proliferation, apoptosis, and migration. Together, our results suggest that miR-615-3p is a significant predictor of postoperative BCR and PC-specific survival and has oncogenic functions in PC cells.

Examining the Role of Dietary Advanced Gycation End Products in Prostate Cancer Using Molecular Imaging Techniques (OR04-08-19)

ObjectivesThe Receptor for Advanced Glycation End Products (RAGE) and its ligands have been shown to be both over expressed and critical to prostate cancer (PCa) development. Importantly, the overexpression of both RAGE and its ligands is associated with poor PCa patient survival, suggesting its promise as a molecular target. Additionally, one of the largest sources of ligands for RAGE, advanced glycation end products (AGEs), come from one’s diet and their concentrations are directly related to disease. We hypothesized that dietary AGEs (dAGEs) significantly contribute to the progression of PCa through interactions with RAGE. In this study we explore the use of a novel imaging strategy targeted at RAGE in combination with conventional imaging and histological techniques to assess the role of dAGEs on RAGE expression and PCa progression in murine xenografts. MethodsTo examine the impact of AGEs on PCa cell function, experiments were performed in two PCa cell lines. Cells were grown in growth media enriched with carboxymethyl-lysine-modified human serum albumin (CML) (the most common AGE) or a control protein, bovine serum albumin (BSA). Western blot, confocal microscopy, clonogenic assays, and proliferations assays were performed. To study the effects of an enhanced consumption of dAGEs on PCa growth and progression in vivo, NU/J mice were fed a modified Ain-93 G diet, which was either CML or BSA enriched. PCa tumors were then initiated. Their growth was monitored, their perfusion measured using Speckle Contrast Imaging, and their metabolic rate and RAGE content quantified using 18FDG and a novel RAGE-targeted tracer using PET-CT. Finally, the tissues were excised for histological analysis. ResultsCML significantly enhanced in vitro expression of both RAGE and proliferation marker KI-67. Cell doubling time was also significantly quickened, (1.5 vs 2.4 days) in the CML vs control. In vivo data demonstrated significant differences in tumor growth (CML group up to 2-fold increase) and successful tumor implantation rate (30% vs 60%). Perfusion, metabolism, and RAGE imaging demonstrated unique patterns which varied over the course of PCa progression. ConclusionsThese studies indicate that dAGEs may play a significant role in the progression of PCa. The data suggests that RAGE and its ligands are promising targets for further therapeutic investigations. Funding SourcesUniversity of Illinois at Chicago Cancer Center Pilot Grant. Supporting Tables, Images and/or Graphs▪

MiR-492 exerts tumor-promoting function in prostate cancer through repressing SOCS2 expression.

MiRNAs have been verified to play a role in the development and progression of prostate cancer (PCa). However, the role of miR-492 in PCa has not been mentioned. We aim to detect the expression of miR-492 in PCa and explore its underlying mechanism. The relative expression of miR-492 in PCa tissue samples to normal prostate tissues was detected using quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The level of miR-492 in PCa-derived cell lines compared with the normal prostate cell line was also measured. Cell counting kit-8 (CCK-8) and colony formation assays were employed to investigate the cell proliferation ability. Transwell assay and wound-healing assays were utilized to explore the cell invasion and migration abilities. Luciferase assay and Western blot were utilized to explore the underlying mechanism of miR-492 in PCa cells. MiR-492 expressed significantly higher in PCa tissues than that in the normal tissues. Its expression level was also over-expressed in PCa cells compared with that in the normal cells. The up-regulation of miR-492 promoted the growth, invasion, and migration of the cells, while down-regulation had the opposite effects. SOCS2 was identified as a potential target for miR-492 in PCa. Silencing of SOCS2 could neutralize the inhibitory function of miR-492 inhibitor in PCa cells. This study demonstrated that miR-492 was over-expressed in PCa and exerted tumor-promoting function in PCa cells via repressing SOCS2 expression. This might provide a new sight for future accurate therapy for PCa.

MicroRNA-107 inhibits proliferation of prostate cancer cells by targeting cyclin E1.

Previous studies have reported that miR-107 could be utilized as a potential peripheral biomarker in prostate cancer (PCa). However, the specific functions of miR-107 in prostate cancer and its relevant mechanisms are still unknown. The aim of this research was to investigate the cellular functions of miR-107 in PCa and reveal the relevant mechanisms. MicroRNA tailing quantitative real-time PCR (qRT-PCR) was adopted to measure the expression of miR-107 in PCa cell line DU145 and PC3, as well as in normal prostate cell line RWPE-1. The miR-107 expression pattern in PCa tissues and paired peritumoral tissues were determined by Chromogenic In Situ Hybridization (CISH). Cell viability, colony formation, flow cytometry cell cycle and apoptosis, wound healing and Transwell migration assays were performed to study the miR-107 functions in PCa cells. Further, qRT-PCR, western blot analysis and dual-luciferase reporter assays were conducted to verify the target of miR-107 in PCa. Results demonstrated that miR-107 was downregulated in PCa cells and tissues in comparison with normal prostate cells and peritumoral tissues, and the over-expression of miR-107 suppressed proliferation and induced G1/S arrest of PCa cells but had no effects on apoptosis or cell motility of PCa cells. MiR-107 was found to target cyclin E1 (CCNE1) in PCa cells by directly binding to its 3'-UTR. In conclusion, miR-107 could be a potential tumor suppressor in PCa, and the restoration of miR-107 might provide a new therapeutic option for PCa.

Pituitary tumor transforming gene binding factor (PBF) is required for androgen-induced prostate cancer proliferation and invasion.

Pituitary tumor transforming gene binding factor (PBF) is a proto-oncogene that plays a role in many cancers; however, its involvement in prostate cancer (PCa) remains unclear. Here, we examined PBF expression in clinical specimens and investigated its regulation and function in human PCa cell lines. Immunohistochemical staining of patient tissues revealed higher PBF expression in PCa than in benign prostatic hyperplasia or adjacent normal prostate specimens. In LNCaP and 22Rv1 cells, PBF expression was upregulated by androgen treatment in a manner partially blocked by the androgen receptor (AR) antagonist bicalutamide. We identified a novel androgen response element in the PBF gene promoter and demonstrated its functional relevance using luciferase reporter assays. Androgen treatment of LNCaP cells induced binding between the endogenous AR and the androgen response element in PBF, as measured by chromatin immunoprecipitation assays. Finally, RNA interference of PBF expression significantly reduced androgen-induced LNCaP cell growth and invasion. Thus, PBF is a novel AR target gene and plays a role in androgen-induced proliferation and metastatic functions in PCa cells.

Angiomotin to regulate prostate cancer cell proliferation by signaling through Hippo-YAP pathway.

e559 Background: Angiomotin (AMOT) is a family of proteins found to be a component of the apical junctional complex of vertebrate epithelial cells and is recently found to play important roles in neurofibromatosis type 2 (NF-2). Whether AMOT plays a role in prostate cancer (PCa) is unknown. Methods: Purified GST-AMOTp80 was used as immunogen for antibody generation. Real-time PCR, western blot and immunohistochemistry were used to identify the expression of AMOT. To study the function of AMOT, retroviral vector were constructed, also shRNA was used to knockdown AMOT in cells. Cell migration and invasion assays were performed by using transwell chambers. Nuclear and cytoplasmic protein fractions were prepared by using NE-PER reagents (Pierce). The SPSS 19.0 software was used for statistical analysis. Chi-square test and t test were used for the comparisons between groups. Results: AMOT is expressed as two isoforms, AMOTp80 and AMOTp130, which has a 409 aa N-terminal domain that is absent in AMOTp80. Both AMOTp80 and AMOTp130 are expressed in LNCaP and C4-2B4, but at a low to undetectable level in PC3 cells. Further study showed that AMOTp130 and AMOTp80 have distinct functions in PCa cells. We found that AMOTp80 functioned as a tumor promoter by enhancing PCa cell proliferation while AMOTp130 did not. Mechanistic studies showed that AMOTp80 signaled through the Hippo pathway by promoting the nuclear translocation of YAP, resulting in an increased expression of YAP target protein BMP4. Moreover, inhibition of BMP receptor activity by LDN-193189 abrogates AMOTp80-mediated cell proliferation. Conclusions: Together, this study reveals a novel mechanism whereby the AMOTp80-Merlin-MST1-LATS-YAP-BMP4 pathway leads to AMOTp80-induced tumor cell proliferation.

Angiomotin regulates prostate cancer cell proliferation by signaling through the Hippo-YAP pathway.

Angiomotin (AMOT) is a family of proteins found to be a component of the apical junctional complex of vertebrate epithelial cells and is recently found to play important roles in neurofibromatosis type 2 (NF-2). Whether AMOT plays a role in prostate cancer (PCa) is unknown. AMOT is expressed as two isoforms, AMOTp80 and AMOTp130, which has a 409 aa N-terminal domain that is absent in AMOTp80. Both AMOTp80 and AMOTp130 are expressed in LNCaP and C4-2B4, but at a low to undetectable level in PC3, DU145, and BPH1 cells. Further study showed that AMOTp130 and AMOTp80 have distinct functions in PCa cells. We found that AMOTp80, but not AMOT p130, functioned as a tumor promoter by enhancing PCa cell proliferation. Mechanistic studies showed that AMOTp80 signaled through the Hippo pathway by promoting nuclear translocation of YAP, resulting in an increased expression of YAP target protein BMP4. Moreover, inhibition of BMP receptor activity by LDN-193189 abrogates AMOTp80-mediated cell proliferation. Together, this study reveals a novel mechanism whereby the AMOTp80-Merlin-MST1-LATS-YAP-BMP4 pathway leads to AMOTp80-induced tumor cell proliferation.

Knockdown of GPR137,G Protein‐coupled receptor 137, Inhibits the Proliferation and Migration of Human Prostate Cancer Cells

GPR137 belongs to the G protein-coupled receptor family involving the regulation of transmembrane signal transduction that launches pivotal cellular functions. However, its function in prostate cancer (PCa) has been rarely reported. It was found in this study that GPR137 was upregulated in PCa tissues as compared with that in paracancerous tissues. To see whether GPR137 could serve as a potential therapeutic target for PCa, GPR137 was knocked down to verify its biological function in PCa cells. Lentivirus-introduced short hairpin RNA (shRNA) was designed to silence GPR137 gene. It was found that silencing of GPR137 gene suppressed the proliferation and colony formation of PCa cell lines PC-3 and DU145. Further study indicated that growth inhibition by GPR137 knockdown was associated with cell cycle arrest at G0/G1 phase. Furthermore, silencing of GPR137 repressed the invasion and migration abilities of PC-3 cells via downregulating slug and snail and upregulating E-cadherin. Collectively, these findings imply that GPR137 plays an important role in the occurrence and progression of PCa and may prove to be a potential therapeutic target for the treatment of advanced PCa.

Abstract 2065: TMEFF2 is a novel androgen receptor co-activator in prostate cancer cells

Abstract The goal of this study is to delineate the role of a novel androgen receptor (AR) coactivator in advanced prostate cancer (PCa). While great advances have been made in the ability to detect PCa, the disease remains the second leading cause of cancer related deaths in men. The AR is a steroid nuclear receptor that serves a central function in both normal prostate cell homeostasis and in PCa; in fact, the vast majority of PCa tumors require androgens for growth. This dependency has led to the development and use of androgen deprivation therapies (ADTs) for the treatment of PCa. ADT is initially a successful form of treatment for most PCa patients; however, the majority of patients eventually relapse with castration-resistant prostate cancer (CRPC), which is currently incurable. Because sustained AR activity under androgen depleted conditions is a major contributor to the development of CRPC, identifying molecular mechanisms that contribute to AR activity in CRPC is paramount for the development of successful therapies. Our lab has been studying the role of the transmembrane protein with epidermal-like growth factor domain and two follistatin domains 2 (TMEFF2) in PCa. While TMEFF2 gene expression is repressed by hypermethylation in multiple cancers, TMEFF2 is overexpressed in PCa and CRPC, suggesting that TMEFF2 may have a unique function in PCa. Importantly, TMEFF2 expression is activated by the androgen receptor (AR) at the level of transcription and translation, which may contribute to its overexpression in PCa. Our data presented here indicate that TMEFF2 functions in PCa cells as a coactivator of the AR. Using shRNA to stably knockdown TMEFF2 expression in androgen dependent PCa and CRPC cell lines, we demonstrate that TMEFF2 activates the basal and androgen-induced expression of multiple androgen responsive genes, including prostate-specific antigen (PSA), at the mRNA and protein level. Importantly, the knock-down of TMEFF2 does not alter AR protein levels, indicating that TMEFF2 influences AR activity. Additionally, by coimmunoprecipitation analysis, we demonstrate that TMEFF2 interacts with the AR, and western blot analyses with cellular fractionation samples indicate that TMEFF2 has the ability to translocate to the nucleus of PCa cells. Based on these results, we conclude that TMEFF2 is a novel AR coactivator in PCa. Future studies will focus on understanding the nature and biological effects of the interaction between TMEFF2 and the AR, and delineating the molecular mechanism through which TMEFF2 activates AR-mediated gene expression. Because sustained AR activity in androgen depleted conditions is a major contributor to CRPC relapse and PCa mortality, the TMEFF2-mediated AR activation mechanism may be clinically useful as a therapeutic target in CRPC. Citation Format: Joshua Corbin, Thomas Green, Maria J. Ruiz-Echevarria. TMEFF2 is a novel androgen receptor co-activator in prostate cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2065. doi:10.1158/1538-7445.AM2015-2065

Abstract 5050: Proteome-based combined treatment strategies synergizing antagonism of androgen receptor function in prostate cancer

Abstract Acquired resistance to second-generation androgen receptor (AR)-targeted therapies compels the development of novel therapeutic agents for castration-resistant prostate cancer (CRPC). We have recently reported a novel function of endostatin (ES) through direct binding and inhibition of AR in human prostate cancer (PCa) cells. Molecular characterization of the putative mechanisms of ES function on AR-positive PCa cells by global proteomic analysis revealed dramatic upregulation of CYP51A1 expression in LNCaP cells, suggesting that the increases in cholesterol biosynthesis and the resultant steroidogenesis may provide survival mechanism for PCa cells through the augmentation of androgen-AR axis. To validate this hypothesis, anti-proliferative effects of combined treatment of ES with Lovastatin or Fluconazole, inhibitor of HMG-CoA reductase or CYP5A1, were analyzed in vitro using AR-positive LNCaP cells. Results indicated a significantly enhanced ES-mediated growth inhibition on LNCaP cells by targeting both the ligand biosynthesis and receptor function. Proteomic profiling further indicated that ES significantly decreased the levels of AR, coactivator Ran (ARA24) and downregulated AR-driven expression of MCM complex 2, 3, 4 and 6, MDC1 and STMN1, suggesting that AR-targeted effects of ES include disruption of DNA replication, cell cycle propagation and cell division. We found that dual inhibition of AR nuclear transport and AR-mediated cell division by co-treatment of ES and Taxol greatly decreased PCa cell proliferation. Together, this interdisciplinary approach integrating proteomics with PCa cell function possibly suggests that antagonism of AR, which is the principal drug target for the PCa treatment, can be potentiated by the combination of ES with currently used chemotherapy agents and adjuvants. These findings further provide new insights into proteome-based approach as a useful tool to design and optimize effective therapeutic regimens for individual patients with CRPC. Citation Format: Joo Hyoung Lee, James A. Mobley, Selvarangan Ponnazhagan. Proteome-based combined treatment strategies synergizing antagonism of androgen receptor function in prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5050. doi:10.1158/1538-7445.AM2015-5050

Androgen receptor and chemokine receptors 4 and 7 form a signaling axis to regulate CXCL12-dependent cellular motility.

BackgroundIdentifying cellular signaling pathways that become corrupted in the presence of androgens that increase the metastatic potential of organ-confined tumor cells is critical to devising strategies capable of attenuating the metastatic progression of hormone-naïve, organ-confined tumors. In localized prostate cancers, gene fusions that place ETS-family transcription factors under the control of androgens drive gene expression programs that increase the invasiveness of organ-confined tumor cells. C-X-C chemokine receptor type 4 (CXCR4) is a downstream target of ERG, whose upregulation in prostate-tumor cells contributes to their migration from the prostate gland. Recent evidence suggests that CXCR4-mediated proliferation and metastasis of tumor cells is regulated by CXCR7 through its scavenging of chemokine CXCL12. However, the role of androgens in regulating CXCR4-mediated motility with respect to CXCR7 function in prostate-cancer cells remains unclear.MethodsImmunocytochemistry, western blot, and affinity-purification analyses were used to study how androgens influenced the expression, subcellular localization, and function of CXCR7, CXCR4, and androgen receptor (AR) in LNCaP prostate-tumor cells. Moreover, luciferase assays and quantitative polymerase chain reaction (qPCR) were used to study how chemokines CXCL11 and CXCL12 regulate androgen-regulated genes (ARGs) in LNCaP prostate-tumor cells. Lastly, cell motility assays were carried out to determine how androgens influenced CXCR4-dependent motility through CXCL12.ResultsHere we show that, in the LNCaP prostate-tumor cell line, androgens coordinate the expression of CXCR4 and CXCR7, thereby promoting CXCL12/CXCR4-mediated cell motility. RNA interference experiments revealed functional interactions between AR and CXCR7 in these cells. Co-localization and affinity-purification experiments support a physical interaction between AR and CXCR7 in LNCaP cells. Unexpectedly, CXCR7 resided in the nuclear compartment and modulated AR-mediated transcription. Moreover, androgen-mediated cell motility correlated positively with the co-localization of CXCR4 and CXCR7 receptors, suggesting that cell migration may be linked to functional CXCR4/CXCR7 heterodimers. Lastly, CXCL12-mediated cell motility was CXCR7-dependent, with CXCR7 expression required for optimal expression of CXCR4 protein.ConclusionsOverall, our results suggest that inhibition of CXCR7 function might decrease the metastatic potential of organ-confined prostate cancers.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1201-5) contains supplementary material, which is available to authorized users.

CMTM5 is reduced in prostate cancer and inhibits cancer cell growth in vitro and in vivo.

A novel tumor suppressor CKLF-like MARVEL transmembrane domain-containing member 5 (CMTM5) is reduced or undetectable in many kinds of cancers and inhibits tumor cells' malignant features. To explore its role in prostate cancer (PCa), we detected its expression patterns in prostate tissues and PCa cells, and determined its anti-proliferation functions in PCa cells in vitro and in vivo. The expression of CMTM5 in prostate tissue microarray, specimens and cell lines was evaluated by immunohistochemistry and Western blot, respectively. After being transfected with CMTM5 adenovirus or vector, the proliferation and migration of DU145 cells were detected by MTT assay and transwell assay, respectively. Furthermore, the effects of CMTM5 on tumor growth were performed in nude mice xenograft in vivo. We found CMTM5 was reduced in PCa tissues and cells compared with BPH tissues, and its expression in PCa tissues was related to the Gleason score. Moreover, after being transfected with adenovirus, ectopic expression of CMTM5-v1 in DU145 cells led to significant inhibition of cell proliferation and migration compared with the control, which may be attributed to decreased Akt activity. Finally, restoration of CMTM5 significantly suppressed tumor growth in vivo. These results indicate that CMTM5 is down-regulated in PCa and exhibit tumor suppressor activities in androgen-independent PCa cells. Loss of CMTM5 protein may be contributed to the development of PCa and it is a potential therapeutic target for castration-resistant prostate cancer.

Abstract 3307: Angiomotin regulates the Hippo pathway to increase prostate cancer cell growth

Abstract Angiomotin (AMOT) is a member of the motin family that consists of three members, AMOT, AMOTL1, and AMOTL2, which function as either positive or negative regulators of cell growth depending on interacting proteins and cellular context. The role of AMOT in prostate cancer (PCa) has not been studied. AMOT is expressed as two isoforms, AMOTp80 and AMOTp130. The AMOTp130 isoform has an extended 409 aa N-terminal domain that is absent in AMOTp80. Both AMOTp80 and AMOTp130 are expressed in LNCaP and C4-2B4, but at a very low level in PC3-mm2 PCa cells. We found that expression of AMOTp130 and AMOTp80 have distinct functions in PCa cells. While AMOTp80 functions as a tumor promoter by enhancing PCa cell proliferation, AMOTp130 did not. We further show that AMOTp80 affects the Hippo tumor suppressor pathway by inhibiting LATS1 and YAP phosphorylation, resulting in nuclear translocation of YAP. Once in the nucleus, YAP increases transcription of the target protein BMP4. Moreover, inhibition of BMP receptor activity by LDN-193189 abrogates AMOTp80-mediated proliferation. These observations suggest that AMOTp80 induces the expression of BMP4, which functions in an autocrine manner to promote PCa cell proliferation. Together, our studies identify AMOTp80-MST-LATS1-YAP-BMP4 as a novel signal pathway that regulates PCa cell proliferation. Citation Format: Angelica Ortiz, Hao Zeng, Sue-Hwa Lin. Angiomotin regulates the Hippo pathway to increase prostate cancer cell growth. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3307. doi:10.1158/1538-7445.AM2014-3307

Arrestin2 modulates androgen receptor activation.

Androgen receptor (AR) has a pivotal role in the growth and survival of prostate cancer (PCa). Arrestin2 (Arr2) is a ubiquitous scaffolding/adaptor protein first characterized as a regulator of G protein-coupled receptor signaling. In this study, we report that Arr2 additionally functions as a positive regulator of AR expression and function in PCa cells. Expression level of Arr2 correlates with that of AR, and knockdown of Arr2 inhibits the expression of AR and its effectors prostate-specific antigen, transmembrane protease serine 2, FK506-binding protein 51 and fatty acid synthase. Mechanistically, the knockdown of Arr2 attenuates the binding of AR to androgen response elements and consequently decreases transcription of AR-regulated genes. The inhibition of AR by Arr2 knockdown occurs in both androgen-dependent and castration-resistant PCa (CRPC) cells, although the effect is more prominent in CRPC. Arr2 knockdown inhibits the in vitro CRPC cell proliferation, prostasphere growth and invasion, as well as the in vivo prostate tumor formation, local invasion and distant metastasis. These results illustrate a new role for Arr2 in the expression and activation of AR and its potential relevance as a target for therapeutic intervention and monitoring of disease progression.