Inhibits Prostate Cancer Progression Research Articles

EMPOWER Men to Reduce Weight and Inhibit Prostate Cancer Progression

EMPOWER Men to Reduce Weight and Inhibit Prostate Cancer Progression

Sight and switch off: Nerve density visualization for interventions targeting nerves in prostate cancer.

Nerve density is associated with prostate cancer (PCa) aggressiveness and prognosis. Thus far, no visualization methods have been developed to assess nerve density of PCa in vivo. We compounded propranolol-conjugated superparamagnetic iron oxide nerve peptide nanoparticles (PSN NPs), which achieved the nerve density visualization of PCa with high sensitivity and high specificity, and facilitated assessment of nerve density and aggressiveness of PCa using magnetic resonance imaging and magnetic particle imaging. Moreover, PSN NPs facilitated targeted therapy for PCa. PSN NPs increased the survival rate of mice with orthotopic PCa to 83.3% and decreased nerve densities and proliferation indexes by more than twofold compared with the control groups. The present study, thus, developed a technology to visualize the nerve density of PCa and facilitate targeted neural drug delivery to tumors to efficiently inhibit PCa progression. Our study provides a potential basis for clinical imaging and therapeutic interventions targeting nerves in PCa.

RETRACTED: MCM3AP-AS1 KD Inhibits Proliferation, Invasion, and Migration of PCa Cells via DNMT1/DNMT3 (A/B) Methylation-Mediated Upregulation of NPY1R

Prostate cancer (PCa) is a heterogeneous tumor that commonly occurs among males worldwide. This study explored the potential role that long non-coding RNA MCM3AP antisense RNA 1 (MCM3AP-AS1) plays in PCa progression, and investigated its mechanism. MCM3AP-AS1 and neuropeptide Y receptor Y1 (NPY1R) expression was determined in PCa cells. The regulatory role of MCM3AP-AS1 in PCa cells was defined using scratch test, Transwell assay, 5-ethynyl-2′-deoxyuridine (EdU) assay, and flow cytometry. Methylation-specific PCR (MSP) was used to test the methylation level of NPY1R. Subsequently, the interaction among MCM3AP-AS1, DNA methyltransferase (DNMT)1/DNMT3 (A/B), and NPY1R was investigated using RNA immunoprecipitation, RNA pull-down, and chromatin immunoprecipitation. Finally, we observed xenograft tumor in nude mice. MCM3AP-AS1 was highly, whereas NPY1R was poorly, expressed in PCa. Lentivirus-mediated overexpression of MCM3AP-AS1 promoted proliferation, invasion, and migration while suppressing apoptosis of PCa cells, whereas opposite trends were detected after inhibition of the mitogen-activated protein kinase (MAPK) pathway. MCM3AP-AS1 promoted methylation of NPY1R promoter via recruitment of DNMT1/DNMT3 (A/B), thereby downregulating NPY1R expression to activate the MAPK pathway. Furthermore, overexpressed MCM3AP-AS1 was observed to facilitate PCa development in vivo, which could be reversed by overexpressed NPY1R. Altogether, MCM3AP-AS1 silencing inhibits PCa progression by disrupting methylation of the NPY1R promoter to inactivate the MAPK pathway.

MALAT1 knockdown inhibits prostate cancer progression by regulating miR-140/BIRC6 axis

BackgroundProstate cancer (PCa) is the second most common cancer among men globally. Long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been reported to be implicated in tumorigenesis and progression of PCa. However, the pathogenesis of MALAT1 in PCa has not been thoroughly elaborated. MethodsRT-qPCR assay was conducted to measure expression of MALAT1, microRNA-140 (miR-140) and Baculoviral IAP repeat containing 6 (BIRC6) mRNA. Protein expression of BIRC6 was detected by western blot assay. Cell proliferative ability was assessed by MTS and Edu retention assays. Cell migratory and invasive abilities were evaluated by wound healing assay and Transwell invasion assay, respectively. Cell apoptotic rate was examined using a flow cytometry. The interaction between miR-140 and MALAT1 or BIRC6 3′UTR was explored by luciferase, RNA immunoprecipitation (RIP) and RNA pull down assays. Xenograft models of PCa were established to further explore the role and molecular mechanism of MALAT in PCa tumorigenesis in vivo. ResultsMALAT1 and BIRC6 were highly expressed in human PCa tumor tissues and cell lines. MALAT1 or BIRC6 knockdown inhibited cell proliferation, migration and invasion and induced cell apoptosis in PCa. MiR-140 could directly bind with MALAT1 or BIRC6 3′UTR. Moreover, MALAT1 knockdown inhibited BIRC mRNA and protein expression through upregulating miR-140 in PCa cells. Additionally, MALAT1 knockdown inhibited PCa xenograft tumor growth by regulating miR-140/BIRC6 axis in vivo. ConclusionMALAT1 knockdown hindered PCa progression by regulating miR-140/BIRC6 axis in vitro and in vivo, hinting the potential value of MALAT1 in the management of PCa.

Phosphoribosyl pyrophosphate synthetases 2 knockdown inhibits prostate cancer progression by suppressing cell cycle and inducing cell apoptosis.

Phosphoribosyl pyrophosphate synthetases 2 (PRPS2) protein function as nucleotide synthesis enzyme that plays vital roles in cancer biology. However, the expression profile and function of PRPS2 in prostate cancer (PCa) remain to be identified. Here we investigated the expression of PRPS2 protein in human PCa and paired normal tissues by immunohistochemistry, meanwhile the regulatory effects on cell proliferation, apoptosis and growth of xenograft tumors in nude mice were evaluated in PCa cells with PRPS2 depletion. Moreover, the signaling pathways were also explored by western blot analysis and quantitative polymerase chain reaction assays. We found that PRPS2 was dramatically upregulated in prostate adenocarcinoma tissues in comparison with normal tissues, and that increased PRPS2 was linked intimately to advanced clinical stage and pT status. Functional experiments showed that knockdown of PRPS2 significantly suppressed cell growth both in vitro and in vivo. In addition, depletion of PRPS2 induced G1 phase cell cycle arrest and elevated cell apoptosis. Silencing of PRPS2 resulted in the decreased expression of Bcl‑2 and cyclinD1 and increased levels of Bax, cleavage of caspases‑3, caspases‑9 and PARP. Furthermore, we also detected PRPS2 expression was significantly induced after DHT treatment, which implied the important role of PRPS2 in oncogenesis of PCa. Taken together, our findings elucidated that PRPS2 may be a potential novel candidate for PCa therapy.

Transcriptional regulation of G2/M regulatory proteins and perturbation of G2/M Cell cycle transition by a traditional Chinese medicine recipe.

Hedyotis diffusa Willd. (H) and Scutellaria barbata D.Don (S) are ancient anti-cancer Chinese herb medicines. When combined, known as HS, it is one of the most commonly prescribed Chinese Medicines for cancer patients today in China. The prevention of disease progression is a dominant concern for the growing number of men with prostate cancer. The purpose of this work is to evaluate the action and mode of action of Chinese Medicine recipe HS in inhibiting prostate cancer progression in preclinical models. Effects of HS were analyzed in prostate cancer cell lines by evaluating proliferation, cell cycle profile, DNA damage and key regulators responsible for G2 to M phase transition. The transcriptional activities of these regulators were determined by RT-PCR and ChIP. The efficacy of HS in vitro was validated in an animal model. HS treatment was observed to reduce DNA content and accumulated prostate cancer cells at the G2/M phase. Immunolabeling for phospho-Histone H3 in association with nocodazole to capture mitotic cells confirmed that HS impeded G2 to M transition. After excluding DNA damage-induced G2 arrest, it was revealed that HS reduced expression of Cyclin B1, CDK1, PLK1 and Aurora A at both protein and mRNA levels, with concomitant reduction of H3K4 tri-methylation at their promoter-regions. Animals that received oral administration of HS with a dosage relevant to clinical application showed reduced tumor volume and weight with a reduction of Cyclin B1, CDK1, PLK1 and Aurora A protein levels. HS acts by impeding the G2 to M transition of prostate cancer cells. It is likely that the mode of action is transcriptionally suppressing proteins governing mitotic entry, without eliciting significant DNA damage.

Pentamidine inhibits prostate cancer progression via selectively inducing mitochondrial DNA depletion and dysfunction.

ObjectivesWe investigated the anti‐cancer activity of pentamidine, an anti‐protozoal cationic aromatic diamidine drug, in prostate cancer cells and aimed to provide valuable insights for improving the efficacy of prostate cancer treatment.Materials and methodsProstate cancer cell lines and epithelial RWPE‐1 cells were used in the study. Cell viability, wound‐healing, transwell and apoptosis assays were examined to evaluate the influences of pentamidine in vitro. RNA‐seq and qPCR were performed to analyse changes in gene transcription levels upon pentamidine treatment. Mitochondrial changes were assessed by measuring mitochondrial DNA content, morphology, membrane potential, cellular glucose uptake, ATP production and ROS generation. Nude mouse xenograft models were used to test anti‐tumour effects of pentamidine in vivo.ResultsPentamidine exerted profound inhibitory effects on proliferation, colony formation, migration and invasion of prostate cancer cells. In addition, the drug suppressed growth of xenograft tumours without exhibiting any obvious toxicity in nude mice. Mechanistically, pentamidine caused mitochondrial DNA content reduction and induced mitochondrial morphological changes, mitochondrial membrane potential dissipation, ATP level reduction, ROS production elevation and apoptosis in prostate cancer cells.ConclusionsPentamidine can efficiently suppress prostate cancer progression and may serve as a novel mitochondria‐targeted therapeutic agent for prostate cancer.

A novel androgen-reduced prostate-specific lncRNA, PSLNR, inhibits prostate-cancer progression in part by regulating the p53-dependent pathway.

Prostate cancer (PCa) is one of the most common cancers in males in China. Long noncoding RNAs (lncRNAs) reportedly play crucial roles in human cancer progression in many studies. However, the molecular mechanisms underlying PCa progression remain unclear. We investigated the lncRNA transcriptome using publicly available RNA-sequencing data to identify prostate-specific lncRNAs. Then, the chromatin immunoprecipitation (ChIP) assay identified lncRNA with a direct binding to androgen receptor (AR), hereafter denoted as PSLNR. Quantitative real-time polymerase chain reaction analysis and Western blot analysis were performed to detect the expression of p53 signaling-related genes after overexpression PSLNR. The effects of overexpression of PSLNR on cell proliferation, cell cycle, and cell apoptosis were assessed by using CCK-8 and flow cytometric analysis. We then detected the expression of PSLNR in tissues. We reported a novel androgen-reduced prostate-specific lncRNA, PSLNR, that inhibited PCa progression via the p53-dependent pathway. By analyzing the NOCODE data set, we reported that PSLNR was specifically expressed in the prostate, suggesting the potential of PSLNR as a biomarker for PCa treatment. The AR pathway was also confirmed to be an upstream regulation signaling pathway of PSLNR by transcriptionally regulating its expression in androgen-dependent PCa cells. PSLNR also significantly inhibited PCa proliferation by inducing cell apoptosis in a p53-dependent manner. Thus, PSLNR may be a candidate diagnosis and therapeutic target for PCa. Our study revealed for the first time a novel androgen-reduced prostate-specific lncRNA, PSLNR, which inhibited PCa progression via the p53-dependent pathway, suggesting that PSLNR may be a candidate diagnosis and therapeutic target for PCa.

Abstract 5086: Acetyl-L-carnitine (ALCAR) inhibits angiogenesis, migration and macrophage recruitment in prostatic cancer cells

Abstract Many efforts have been addressed on the identification of novel active compounds from natural sources, endowed with anti-proliferative, anti-oxidant, chemopreventive properties, and their ability to target the tumour microenvironment (TME). Through metabolomics approaches we previously found that in serum samples from prostate cancer (PCa) patients, three carnitine family members were significantly decreased, suggesting a potential protective role of carnitine against PCa. Acetyl-L-carnitine(ALCAR) is an aceticacid ester of carnitine with high bioavailability and is involved in the transportof fatty acids across the inner mitochondrial membrane. We have showed that ALCAR was able reduce angiogenesis in vitro, acting on the VEGF/VEGFR2 and CXCR4/CXCL12 axes. We also found that ALCAR inhibits inflammatory angiogenesis in vivo, by reducing endothelial cells and macrophage recruitment in the matrigel plugs. Here we investigated the ability of ALCAR to interfere with key functional steps of prostate carcinogenesis and identified the molecular mechanisms involved. The effects of ALCAR on PCa cells were investigated in vitro by functional assays (adhesion, migration and invasion assays), molecular and biochemical approaches (RT-PCR, FACS, Byoplex and western blot). We found that ALCAR reduces apoptosis on PCa cells (PC3, Du-145, LNcap) and inhibits crucial tumorigenic steps such as adhesion, migration and invasion. We than confirmed the results from functional assays at molecular levels, and we found that ALCAR blocks CXCR4/CXCL12 axes, a key regulator of malignant migratory/aggressive phenotype. In accordance with our published paper, we confirmed the anti-angiogenic and ant-inflammatory properties of ALCAR, that we found to lower VEGF and CXCL8 production in PCa cell lines. Furthermore, we found a significantly reduced expression of inflammatory-related chemokines/cytokines involved macrophage recruitment such as CCL2, IL-6 and TNFα in PCa cells. Our results highlight the angio/chemopreventive and anti-inflammatory properties of ALCAR and allow the identification of multiple and overlapping mechanisms of action through which ALCAR inhibits PCa progression / metastasis. Our findings provide the rational for the employment of ALCAR, as a possible supplement for approaches of chemoprevention in subjects at high risk to develop cancer. Citation Format: Adriana Albini, Antonino Bruno, Denisa Baci, Matteo Gallazzi, Matilde Tramacere. Acetyl-L-carnitine (ALCAR) inhibits angiogenesis, migration and macrophage recruitment in prostatic cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5086.

Andrographolide alters metabolism and mitochondrial function in prostate cancer

Prostate cancer (PCa) is the second most common diagnosed cancer and the fifth cause of cancer mortality in men worldwide. In the United States, PCa is the most common diagnosed cancer and the third cause of cancer mortality in men. PCa is often treated using radiation, chemotherapy or radical prostatectomy. However, the combination of natural products with the standard of care treatment is an emerging area of cancer therapeutics. Previous studies from our laboratory showed that Andrographolide inhibits prostate cancer progression through a DNA damage response mechanism. In this study, we investigated the role of Andrographolide in metabolic function. Tumor development was performed by using an orthotopic xenograft model in which the prostates of SCID mice were injected with the prostate cancer cell line 22RV1. These mice were treated three times per week with Andrographolide 10 or 25 mg/kg for 4 weeks. Tumor tissue was collected to evaluate the effect of Andrographolide in tumor gene expression. Microarray analysis identified carbohydrate metabolism, connective tissue development and function, and cell cycle as a major molecular and cellular function altered in tumors treated with Andrographolide. Specifically, we found that the expression profiles of SASS6, FBXL4, MYDGF, TKK, MRSP33 and ZNF766 were significantly altered, suggesting that Andrographolide may be altering tumor metabolism. To confirm this observation, bioenergetics profile was determined using an Extracellular Flux Analyzer (Seahorse XF Mito Stress assay). The results of these experiments indicate that Andrographolide treatment decreases the Maximum and Spare Respiratory Capacity of PCa cells. These data suggest that Andrographolide disrupts the bioenergetics profile of PCa cells.Support or Funding InformationWork funded by Institutional funds from the University of Puerto Rico Comprehensive Cancer Center and the School of Pharmacy. HOZ was supported in part by NIH‐NCI grant U54CA096297. MARC grant 5T34GM007821‐38.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

MicroRNA-150 suppresses epithelial-mesenchymal transition, invasion, and metastasis in prostate cancer through the TRPM4-mediated β-catenin signaling pathway.

Prostate cancer (PCa) remains one of the leading causes of cancer-related deaths among males. The aim of the current study was to investigate the ability of microRNA-150 (miR-150) targeting transient receptor potential melastatin 4 (TRPM4) to mediate epithelial-mesenchymal transition (EMT), invasion, and metastasis through the β-catenin signaling pathway in PCa. Microarray analysis was performed to identify PCa-related differentially expressed genes, after which both the mirDIP and TargetScan databases were employed in the prediction of the miRNAs regulating TRPM4. Immunohistochemistry and RT-qPCR were conducted to determine the expression pattern of miR-150 and TRPM4 in PCa. The relationship between miR-150 and TRPM4 expression was identified. By perturbing miR-150 and TRPM4 expression in PCa cells, cell proliferation, migration, invasion, cycle, and apoptosis as well as EMT markers were determined accordingly. Finally, tumor growth and metastasis were evaluated among nude mice. Higher TRPM4 expression and lower miR-150 expression and activation of the β-catenin signaling pathway as well as EMT stimulation were detected in the PCa tissues. Our results confirmed TRPM4 as a target of miR-150. Upregulation of miR-150 resulted in inactivation of the β-catenin signaling pathway. Furthermore, the upregulation of miR-150 or knockdown of TRPM4 was observed to suppress EMT, proliferation, migration, and invasion in vitro in addition to restrained tumor growth and metastasis in vivo. The evidence provided by our study highlights the involvement of miR-150 in the translational suppression of TRPM4 and the blockade of the β-catenin signaling pathway, resulting in the inhibition of PCa progression.

Metformin Inhibits Prostate Cancer Progression by Targeting Tumor-Associated Inflammatory Infiltration.

Purpose: Inflammatory infiltration plays important roles in both carcinogenesis and metastasis. We are interested in understanding the inhibitory mechanism of metformin on tumor-associated inflammation in prostate cancer.Experimental Design: By using a transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse model, in vitro macrophage migration assays, and patient samples, we examined the effect of metformin on tumor-associated inflammation during the initiation and after androgen deprivation therapy of prostate cancer.Results: Treating TRAMP mice with metformin delays prostate cancer progression from low-grade prostatic intraepithelial neoplasia to high-grade PIN, undifferentiated to well-differentiated, and PIN to adenocarcinoma with concurrent inhibition of inflammatory infiltration evidenced by reduced recruitment of macrophages. Furthermore, metformin is capable of inhibiting the following processes: inflammatory infiltration after androgen deprivation therapy (ADT) induced by surgically castration in mice, bicalutamide treatment in patients, and hormone deprivation in LNCaP cells. Mechanistically, metformin represses inflammatory infiltration by downregulating both COX2 and PGE2 in tumor cells.Conclusions: Metformin is capable of repressing prostate cancer progression by inhibiting infiltration of tumor-associated macrophages, especially those induced by ADT, by inhibiting the COX2/PGE2 axis, suggesting that a combination of ADT with metformin could be a more efficient therapeutic strategy for prostate cancer treatment. Clin Cancer Res; 24(22); 5622-34. ©2018 AACR.

Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression.

Emerging studies have shown that the expression of AR splice variants (ARv) lacking ligand-binding domain is associated with castrate-resistant prostate cancer (CRPC) and higher risk of tumor metastasis and recurrence. Nuclear export protein XPO1 regulates the nuclear localization of many proteins including tumor suppressor proteins. Increased XPO1 in prostate cancer is associated with a high Gleason score and bone metastasis. In this study, we found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds selinexor and eltanexor (KPT-8602) down-regulated the expression of AR, AR-v7 and ARv567es at mRNA and protein levels. XPO1 silencing also inhibited the expression of AR and ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. By targeting XPO1/ARv signaling, SINE suppressed prostate cancer (PCa) growth in vitro and in vivo and potentiated the anti-cancer activity of anti-AR agents, enzalutamide and abiraterone. Therefore, XPO1 inhibition could be a novel promising agent used in combination with conventional chemotherapeutics and AR-targeted therapy for the better treatment of PCa, especially CRPC.

MicroRNA-373-3p inhibits prostate cancer progression by targeting AKT1.

This study aims to investigate whether microRNA-373-3p could inhibit the progression of prostate cancer (PCa) by targeting and degrading AKT1. Expression levels of microRNA-373-3p and AKT1 in PCa tissues and benign prostate hyperplasia (BPN) tissues were detected by quantitative Real-Time-Polymerase Chain Reaction (qRT-PCR). According to the follow-up data, survival curves and receiver operating characteristic (ROC) curves were drawn to investigate whether microRNA-373-3p could be served as a biomarker for early diagnosis and prognosis of PCa. The effect of microRNA-373-3p on cell proliferation was examined by cell counting kit-8 (CCK-8) assay. Subsequently, we explored the direct binding condition of AKT1 and microRNA-373-3p by dual-luciferase reporter gene assay and Western blot. QRT-PCR results showed that microRNA-373-3p level was significantly lower in PCa tissues compared with that of BPN tissues, whereas AKT1 expression was significantly increased. By analyzing the survival curve and ROC curve, we found that the overall survival (OS) of PCa patients with higher microRNA-373-3p expression was markedly longer than those with lower expression. Besides, microRNA-373-3p could be used as an early diagnostic marker to distinguish PCa from BPH. Overexpression of microRNA-373-3p in PCa cells (LNCaP and PC3 cells) remarkably inhibited cell proliferation. Dual-luciferase reporter gene assay and Western blot showed that microRNA-373-3p targeted the 3'UTR of AKT1 and inhibited its expression. Downregulated microRNA-373-3p promoted the proliferation of prostate cancer cells via targeting AKT1.

Lycopene exerts anti-inflammatory effect to inhibit prostate cancer progression.

Lycopene is a natural compound that alleviates oxidative stress and inflammation, exerting therapeutic effects in a number of cancers. The aim of this study is to investigate the efficacy of lycopene in inhibiting prostate cancer. Cell viability assays indicated the dose- and time-dependent toxicity of lycopene in prostate cancer cells. Annexin V/propidium iodide double-staining assays revealed the strong apoptotic effects of lycopene. The levels of inflammatory factors, including interleukin-1 (IL1), IL6, IL8, and tumor necrosis factor-α (TNF-α), in lycopene-treated cells were also reduced by lycopene treatment. With the increasing dose of lycopene, the survival of mice bearing prostate cancer xenografts was significantly improved (P < 0.01), and the tumor burden was significantly reduced (P < 0.01). Our results indicate that lycopene is a promising chemotherapy drug, which inhibits prostate cancer progression by suppressing the inflammatory response.

Abstract A070: Targeting N-myristoyltransferase 1 inhibits prostate cancer progression

Abstract N-myristoyltransferase (NMT) facilitates co/post-translational myristoylation of several oncogenic proteins, regulating their functions in tumor progression. N-myristoyltransferase (NMT), which has been shown to be upregulated in a variety of cancers, is overexpressed in androgen-independent prostate cancer cells. We demonstrate that genetically, ablation of NMT1 inhibited proliferation of prostate cancer cells, tumor growth, and suppressed myristoylation profile of prostate cancer cells. Screening a panel of myristoyl-CoA analogs against purified human NMT1 protein leads to identifying the B13 as an inhibitor for NMT1. B13 significantly suppressed prostate cancer cell proliferation, migration, and invasion by cell cycle arrest, and inhibited the growth of prostate xenograft tumors with minimal pathologic effect on major organs in vivo. Structure activity relationship based optimization of B13 led to LCL204, which showed better inhibitory properties towards NMT1. We demonstrate that targeting protein myristoylation is a potential therapeutic approach to inhibit prostate tumor progression. Citation Format: Omar Alsaidan, Sungjin Kim, Octavia Goodwin, Qianjin Li, Aiping Bai, Alicja Bielawska, George Zheng, Iryna Lebedyeva, Thomas Albers, James S. Norris, Scott D. Pegan, Houjian Cai. Targeting N-myristoyltransferase 1 inhibits prostate cancer progression [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A070.

MiR-410–3p promotes prostate cancer progression via regulating PTEN/AKT/mTOR signaling pathway

Prostate cancer has become one of commonest urologic tumors in male. In recent years, miRNAs are continually attracting attentions of researchers for their special regulatory function in human cancers. Previous study has revealed that miR-410 acts as a biomarker for the diagnosis of prostate cancer. Whereas, the specific biological function of miR-410–3p in prostate cancer remains unknown. The aim of this study is to explore the function and molecular mechanism of miR-410–3p in prostate cancer. The high expression of miR-410–3p was examined in prostate cancer tissues and cell lines by qRT-PCR. Next, the prognostic value was identified by Kaplan Meier method. High expression of miR-410–3p indicated poor prognosis of prostate cancer patients. To investigate the biological function of miR-410–3p in prostate cancer, loss-of function assays were designed and performed in two prostate cancer cell lines (PC3 and DU145). As a result, downregulated miR-410–3p suppressed cell proliferation, migration and EMT progress. Moreover, flow cytometry analysis was performed to determine that the acceleration effects of miR-410–3p on cell apoptosis. Mechanistically, further analysis demonstrated that the effects of miR-410–3p exert oncogenic functions through downregulating PTEN. All findings in this study revealed that miR-410–3p inhibits prostate cancer progression via downregulating PTEN/AKT/mTOR signaling pathway.

Abstract 2492: Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression

Abstract Increased XPO1 (a key nuclear exporter of many tumor suppressor proteins [TSPs]) expression in prostate cancer (PCa) has been found to be associated with a high Gleason score and bone metastasis. However, it is unknown whether aberrant XPO1 activity regulates AR and AR splice variants (Arv) signaling in PCa progression. In this study, using 22Rv1 and VCaP prostate cancer cells which harbor full length AR and ARv, we conduct in vitro cellular and molecular biological experiments and in vivo animal studies to elucidate the role XPO1 inhibition plays in PCa progression through regulation of XPO1/AR/ARv signaling. We found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds (selinexor and KPT-8602/eltanexor) down-regulated the expression of AR, AR-v7 and ARv567es at the mRNA and protein levels. Mechanistic studies showed that XPO1 silencing also inhibited the expression of AR/ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. SINE compound treatment of cells retained the eIF4E protein (translation initiation factor and nuclear transporter of capped depended mRNAs) in nuclear compartment, leading to nuclear retention of AR-v7 and PSA mRNAs. The nuclear localization of AR-v7 mRNA resulted in the reduction in the ARv protein. Furthermore, SINE compound treatment retained TSPs including Rb, p21, p53, APC and SMAD4 in the nucleus leading to inhibition of cell proliferation and induction of apoptosis. Moreover, by targeting XPO1/ARv signaling, SINE compounds suppressed prostate cancer growth in vitro and in vivo and potentiated the anti-cancer activity of conventional chemotherapeutic agent docetaxel and anti-AR agents (enzalutamide and abiraterone) through the inhibition of AR, AR-v7, FOXA1, PSA and UBE2C. From these results, we conclude that there is a causal relationship between XPO1 and AR splice variants. High expression of both XPO1 and AR-v7 could lead to constitutively activated AR signaling, CRPC development and progression, and anti-AR drug resistance. By targeting XPO1/AR/ARv signaling and increasing anti-AR sensitivity, SINE compounds could be novel agents used in combination with conventional chemotherapeutics and AR-targeted therapy for the treatment of PCa, especially CRPC. Citation Format: Irfana Muqbil, Yiwei Li, Erkan Baloglu, William Senapedis, Yosef Landesman, Christian Argueta, Michael Kauffman, Sharon Friedlander, Hua Chang, Sharon Shacham, Elisabeth Heath, Asfar S. Azmi. Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression [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 2492.

Abstract 5491: Blocking acyl-CoAs synthesis inhibits prostate cancer progression

Abstract Fatty acid metabolism is essential for the biogenesis of cellular components and ATP production to sustain proliferation of cancer cells. Bioconversion of exogenous or de novo synthesized fatty acids to their corresponding fatty acyl-CoAs, which is required for the fatty acids to participate in metabolic processes, is catalyzed by long chain fatty acyl-CoA synthetases (ACSLs). However, the influence of individual ACSL isoforms on the progression of prostate cancer remains unknown. The goal of this study is to analyze how ACSLs regulates the biosynthesis of acyl-CoAs, thereby prostate cancer progression. In this study, lentivirus carrying shRNA of ACSL1 was constructed and produced in house. Oxygen Consumption Rate (OCR) and Extracellular Acidification Rate (ECAR) were measured by Seahorse. The amount of protein and acyl-CoAs was analyzed by immunoblotting and LC-MS/MS, respectively. Additionally, the amount of triglyceride and neutral lipid were measured by gas Chromatography and Oil red O staining. TCGA database was also used for analysis of ACSL1 expression levels in different stages of prostate cancer. Finally, inhibition of cell proliferation, migration, invasion assays and cell cycle analysis were examined in numerous cancer cells. Prostate xenograft tumor models were applied for in vivo studies. Prostate tumor tissue array was utilized for the analysis of ACSL1 expression. Based on the systematic analysis on the correlation of ACSL expression levels and the amount of intracellular acyl-CoAs, we demonstrate that expression levels of ACSL1 were significantly associated with the levels of a variety of acyl-CoAs, and were elevated in human prostate tumors. ACSL1 increased the biosynthesis of fatty acyl-CoAs including C16:0-, C18:0-, C18:1- and C18:2-CoA, triglycerides and lipid accumulation in cancer cells. In addition, ACSL1 modulated mitochondrial respiration through regulation of carnitine palmitoyltransferase 1A (CPT1A) activity. Knockdown of ACSL1 expression inhibited the cell cycle, and suppressed the proliferation and migration of prostate cancer cells in vitro, and growth of prostate xenograft tumors in vivo. Our study demonstrates ACSL1 plays an important role in prostate tumor progression. Our results provide a therapeutic strategy of targeting fatty acid metabolism for the treatment of prostate cancer. Citation Format: Houjian Cai, Yongjie Ma. Blocking acyl-CoAs synthesis inhibits prostate cancer progression [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 5491.

Abstract 1502: PDEF inhibits prostate cancer progression by promoting luminal differentiation

Abstract Background: The emergence of metastatic castration-resistant prostate cancer (PCa) is accompanied by the loss of prostate luminal cell identity. Cell identity is defined by key transcription factors by association with enhancer and super-enhancer elements. Our previous studies have shown that Sam Pointed Domain Ets Transcription Factor a.k.a. Prostate-Derived Ets Factor (SPDEF/PDEF), inhibits tumor metastasis in vivo. Recently, PDEF has been reported as one of the super enhancer related transcription factors in the luminal PCa cell line LNCaP and observed to be highly expressed in prostate luminal cells. We propose that PDEF functions as a putative tumor metastasis suppressor and inhibits tumor progression by restoring luminal cell identity. The present study was designed to investigate the role of PDEF in metastatic PCa progression. Methods: PC3 and DU145 cells were stably transfected with PDEF/control pBABE retroviral vectors. Global gene expression changes were probed using Affymetrix microarray. Microarray was analyzed with GSEA. qRT-PCR was performed to confirm the differential gene expression profile and immunohistochemistry, immunofluorescence and immunoblot were performed to visualize protein expression. ChIP-seq data were extracted from SRP002475 and aligned with Bowtie. Peaks were identified by MACS2. Clinical data were extracted from GSE16560, GSE21034 and TCGA database. Statistical analysis was performed with GraphPad and R. Results: Analysis of our microarray studies revealed that PDEF expression resulted in the negative enrichment of metastasis-related gene sets and the positive enrichment of gene sets involved in luminal differentiation. Especially, PDEF restores canonical AR signaling in PC3 cells. Confirmed with qPCR, IB and IF, PDEF also inhibits the expression of neuroendocrine-related genes, stemness-related genes while promoting the expression of prostate luminal differentiation-related genes. Furthermore, PDEF ChIP-seq analysis revealed a novel PDEF binding site at the putative promoter region of prostate luminal cell marker cytokeratin 18 while no significant peaks were identified within the regulatory elements of EMT related transcription factors. Our data suggest that PDEF promotes the expression of cytokeratin 18 in vitro and in vivo. Knockdown of cytokeratin 18 by siRNA increases the expression of Twist1 while decreases the expression of E-Cadherin while PDEF expression level is not affected. Moreover, data analysis from multiple clinical prostate cancer cohorts suggests the loss of PDEF is associated with tumor metastasis, tumor progression, and poor survival. Conclusions: PDEF expression leads to luminal differentiation phenotype in advanced prostate cancer cells. PDEF inhibits cell migration and metastasis in part by down-regulating EMT related transcription factors in part through directly promoting the expression of cytokeratin 18. Citation Format: Fengtian Wang, Sweaty Koul, Hari K. Koul. PDEF inhibits prostate cancer progression by promoting luminal differentiation [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 1502.