Mechanisms Of Prostate Cancer Progression Research Articles

ProstaMine: a bioinformatics tool for identifying subtype-specific co-alterations associated with aggressiveness in prostate cancer.

Prostate cancer is a leading cause of cancer-related deaths among men, marked by heterogeneous clinical and molecular characteristics. The complexity of the molecular landscape necessitates tools for identifying multi-gene co-alteration patterns that are associated with aggressive disease. The identification of such gene sets will allow for deeper characterization of the processes underlying prostate cancer progression and potentially lead to novel strategies for treatment. We developed ProstaMine to systematically identify co-alterations associated with aggressiveness in prostate cancer molecular subtypes defined by high-fidelity alterations in primary prostate cancer. ProstaMine integrates genomic, transcriptomic, and clinical data from five primary and one metastatic prostate cancer cohorts to prioritize co-alterations enriched in metastatic disease and associated with disease progression. Integrated analysis of primary tumors defined a set of 17 prostate cancer alterations associated with aggressive characteristics. We applied ProstaMine to NKX3-1-loss and RB1-loss tumors and identified subtype-specific co-alterations associated with metastasis and biochemical relapse in these molecular subtypes. In NKX3-1-loss prostate cancer, ProstaMine identified novel subtype-specific co-alterations known to regulate prostate cancer signaling pathways including MAPK, NF-kB, p53, PI3K, and Sonic hedgehog. In RB1-loss prostate cancer, ProstaMine identified novel subtype-specific co-alterations involved in p53, STAT6, and MHC class I antigen presentation. Co-alterations impacting autophagy were noted in both molecular subtypes. ProstaMine is a method to systematically identify novel subtype-specific co-alterations associated with aggressive characteristics in prostate cancer. The results from ProstaMine provide insights into potential subtype-specific mechanisms of prostate cancer progression which can be formed into testable experimental hypotheses. ProstaMine is publicly available at: https://bioinformatics.cuanschutz.edu/prostamine.

Abstract 2752: ICA1 promotes prostate cancer progression and metastasis via AR down-regulation

Abstract Cancer metastasis, one of the main characteristics in malignancy, contributes to high mortality in cancer patients. Prostate cancer (PCa) is the most common cancer among men and the second leading cause of cancer-related death in Europe and the United States. In China, its incidence has been dramatically increased over past years. However, the mechanism of PCa progression and metastasis remains unclear. The androgen receptor (AR) has been demonstrated to play an important role in PCa progression and metastasis. We have previously established mouse models of PCa bone metastasis and PCa lung metastasis. We have obtained cell clones with bone-specific or lung-specific metastatic capability. By transcriptomic analysis of highly metastatic cell clones and their parental cells, we found a gene group including islet cell autoantigen 1 (ICA1) that are highly expressed in both metastatic cell clones. We further compared these results with RNA array data in clinical samples. Data comparison and correlation analysis showed that ICA1 was negatively correlated with AR expression. Survival analysis of PCa and lung cancer patients showed higher expression of ICA1 but with shorter overall survival. Down-regulation of ICA1 expression in highly metastatic tumor cells significantly inhibited cell growth, colony formation, migration, and invasion. ICA1 overexpression in parental RM1 cells apparently increased cell growth, migration, and metastasis. Interestingly, down-regulation of ICA1 also significantly activated AMPK/mTOR signaling pathway. These findings are anticipated to shed light on the novel pathogenic mechanism underlying PCa and propose a compelling theoretical basis for the application of ICA1 in PCa. This work supported by the NSFC projects (81972420, 81972766, 82173336), as well as grants from the Science and Technology Project of Shenzhen (JCYJ20210324104214040, JCYJ20190809161811237).Keywords: prostate cancer, metastasis, ICA1, androgen receptor Citation Format: Fuhao Wang, Yu He, Xin Huang, Ming Chang, Xiao Zhang, Xiaoyi Li, Xinyu Ye, Yi Lu. ICA1 promotes prostate cancer progression and metastasis via AR down-regulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2752.

Abstract 1680: Roles of EphA2 receptor signaling in prostate cancer development and progression

Abstract Aggressive forms of prostate cancer (PCa), while initially responsive to androgen deprivation therapy (ADT), inevitably become resistant to therapy and are considered castration resistant PCa (CRPC). A major goal of PCa research has been to broadly identify molecular and cellular mechanisms that aid this progression to identify potential therapeutic targets. Using a combination of human data and unique animal models, we found that the receptor tyrosine kinase (RTK) EphA2 is overexpressed specifically in castration resistant and advancing prostate cancers. Furthermore we show that in metastatic PCa the receptor undergoes ligand-independent oncogenic signaling mediated by phosphorylation of EphA2 at S897. Together our data indicate a potential mechanism in PCa progression in which EphA2 becomes overexpressed and aids acquisition of castration resistance via acting as a driver of cell migration, invasion, and proliferation. Citation Format: Ryan Lingerak, Aaron Petty, Hong Guo, Hebei Lin, Xiaojun Shi, Soyeon Kim, Bingcheng Wang. Roles of EphA2 receptor signaling in prostate cancer development and progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1680.

M6A-modified circABCC4 promotes stemness and metastasis of prostate cancer by recruiting IGF2BP2 to increase stability of CCAR1.

Prostate cancer (PCa) is a malignant tumor of the urinary system. CircABCC4 has been demonstrated to promote the development of PCa; however, its regulatory mechanisms in PCa progression remain largely unknown. We found that circABCC4 was highly expressed in PCa tissues and cells, and elevated circABCC4 level indicated a poor overall survival of PCa patients. METTL3 overexpression increased circABCC4 expression via m6A modification in PCa cells. Functionally, knockdown of circABCC4 or METTL3 repressed PCa cell stemness, migration, and invasion in vitro and delayed PCa cancer growth and metastasis in vivo. circABCC4 knockdown-mediated inhibition in PCa cell stemness and metastasis could be counteracted by overexpression of wild-type circABCC4 with m6A sites. Mechanistically, circABCC4 recruited IGF2BP2 protein to CCAR1 mRNA, thereby enhancing CCAR1 mRNA stability and subsequent activation of the Wnt/β-catenin pathway. Overexpression of CCAR1 counteracted the inhibitory effect of circABCC4 silencing on PCa cell stemness and metastasis. These results revealed that m6A-modified circABCC4 by METTL3 facilitated PCa cell stemness and metastasis by interacting with IGF2BP2 to increase the stability and expression of CCAR and subsequent expression of Wnt/β-catenin target genes. Our findings suggest circABCC4 as a promising therapeutic target for PCa.

Abstract IA004: Metabolic mechanisms of prostate cancer progression that feed nuclear receptors

Abstract The androgen axis is central to prostate cancer physiology and therapy. Androgens are gonadal and extragonadal in origin, both of which stimulate the androgen receptor (AR). The use of medical castration (ADT), adrenal androgen ablation (i.e., abiraterone) and potent AR antagonists (i.e., enzalutamide, apalutamide, darolutamide), has yielded complex clinical states of prostate cancer, including disease states that are resistant to multiple forms of hormonal therapy. One of the major questions that arises is whether men can be identified who will benefit from earlier intensive hormonal therapy. Another question is whether alternative hormonal treatment strategies can be used to address resistance to the current generation of hormonal therapies. We propose that identification of steroid metabolic dependencies is part of the answer to both of these questions. Approximately half of men with prostate cancer inherit an activating missense in the first and rate-limiting enzyme that converts extragonadal precursor steroids to dihydrotestosterone (DHT). The “adrenal-permissive” HSD3B1(1245C) allele encodes for a 3β-hydroxysteroid dehydrogenase-1 (3βHSD1) enzyme that increases tumor DHT synthesis from adrenal DHEA. Heterozygous or homozygous HSD3B1(1245C) inheritance confers poor outcomes after ADT. Furthermore, men with HSD3B1(1245C) inheritance and castration-resistant prostate cancer (CRPC) treated with abiraterone or enzalutamide still have poorer outcomes. Together, these data suggest that directly targeting this metabolic lesion is necessary for optimal therapy in these men. We recently discovered that phosphorylation of the 3βHSD1 tyrosine 344 by the BMX kinase is necessary for androgen biosynthesis and CRPC in xenograft models. These findings have led to the launch of the Maverick clinical trial in the Prostate Cancer Clinical Trials Consortium (PCCTC) that combines abiraterone plus BMX inhibition with abivertinib in men with CRPC. In sum, this accumulating body of evidence suggests that steroid metabolic dependencies should be considered as an essential part of cancer metabolism, particularly in the context of developmental therapeutics for prostate cancer. Citation Format: Nima Sharifi. Metabolic mechanisms of prostate cancer progression that feed nuclear receptors [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr IA004.

AMPK targets a proto-oncogene TPD52 (isoform 3) expression and its interaction with LKB1 suppress AMPK-GSK3β signaling axis in prostate cancer.

Tumor protein D52 (TPD52) is a proto-oncogene overexpressed in prostate cancer (PCa) due to gene amplification and it is involved in the cancer progression of many cancers including PCa. However, the molecular mechanisms underlying the role of TPD52 in cancer progression are still under investigation. In this study, we report that the activation of AMP-activated protein kinase (AMPK) by AICAR (5-Aminoimidazole-4-carboxamide ribonucleotide) inhibited the LNCaP and VCaP cells growth by silencing TPD52 expression. Activation of AMPK inhibited the proliferation and migration of LNCaP and VCaP cells. Interestingly, AICAR treatment to LNCaP and VCaP cells led to the downregulation of TPD52 via activation of GSK3β by a decrease of inactive phosphorylation at Ser9. Moreover, in AICAR treated LNCaP cells, inhibition of GSK3β by LiCl attenuated downregulation of TPD52 indicating that AICAR acts via GSK3β. Furthermore, we found that TPD52 interacts with serine/threonine kinase 11 or Liver kinase B1 (LKB1) a known tumor suppressor and an upstream kinase for AMPK. The molecular modeling and MD simulations indicates that the interaction between TPD52 and LKB1 leads to inhibition of the kinase activity of LKB1 as its auto-phosphorylation sites were masked in the complex. Consequently, TPD52-LKB1 interaction may lead to inactivation of AMPK. Moreover, overexpression of TPD52 is found to be responsible for the reduction of pLKB1 (Ser428) and pAMPK (Thr172). Therefore, TPD52 may be playing its oncogenic role via suppressing the AMPK activation. Altogether, our results revealed a new mechanism of PCa progression in which TPD52 overexpression inhibits AMPK activation by interacting with LKB1. These results support that the use of AMPK activators and/or small molecules that could disrupt the TPD52-LKB1 interaction might be useful to suppress PCa cell growth. TPD52 interacts LKB1 and interfere with activation of AMPK in PCa cells.

Circular RNA LPAR3 targets JPT1 via microRNA-513b-5p to facilitate glycolytic activation but repress prostate cancer radiosensitivity

A great many circular RNAs (circRNAs) are considered key modulators of human malignancies. However, the function of circRNA lysophosphatidic acid receptor 3 (LPAR3) in the radioresistance of prostate cancer (PCa) cells is still uncertain. circLPAR3, microRNA (miR)-329-3p, and JPT1 expression in PCa tissues and cells were detected by real-time quantitative PCR or western blot. Cell proliferation was detected by CCK-8 (cell proliferation assay) and colony formation assay, apoptosis was by flow cytometry, and migration and invasion ability were by Transwell assay. Cell glycolysis was analyzed by glucose uptake, lactate production, and ATP metabolism. Under different doses of radiation, the radiosensitivity of PCa cells was detected by colony formation assay. The relationship between circLPAR3, miR-513b-5p, and JPT1 was confirmed by dual luciferase reporter gene detection and RIP assay. The data presented that circLPAR3 and JPT1 expression was elevated in PCa, while miR-513b-5p expression was reduced. Repression of circLPAR3 depressed cell advancement, and restrained glycolysis, but enhanced the radiosensitivity of PCa cells. CircLPAR3's target miRNA was miR-513b-5p which targeted JPT1. Elevated JPT1 reversed the repressive effects of circLPAR3 knockdown or miR-513b-5p overexpression on PCa advancement, glycolysis, and radiosensitivity. In summary, the knockdown of circLPAR3 reduces glycolysis, but promotes PCa radiosensitivity via the miR-513b-5p/JPT1 axis, discovering a novel mechanism in PCa progression.

Recent advances in prostate cancer: WNT signaling, chromatin regulation, and transcriptional coregulators.

Prostate cancer is one of the most common diseases in men worldwide. Surgery, radiation therapy, and hormonal therapy are effective treatments for early-stage prostate cancer. However, the development of castration-resistant prostate cancer has increased the mortality rate of prostate cancer. To develop novel drugs for castration-resistant prostate cancer, the molecular mechanisms of prostate cancer progression must be elucidated. Among the signaling pathways regulating prostate cancer development, recent studies have revealed the importance of noncanonical wingless-type MMTV integration site family (WNT) signaling pathways, mainly that involving WNT5A, in prostate cancer progression and metastasis; however, its role remains controversial. Moreover, chromatin remodelers such as the switch/sucrose nonfermentable (SWI/SNF) complex and chromodomain helicase DNA-binding proteins 1 also play important roles in prostate cancer progression through genome-wide gene expression changes. Here, we review the roles of noncanonical WNT signaling pathways, chromatin remodelers, and epigenetic enzymes in the development and progression of prostate cancer.

Prostate Cancer Epigenetic Plasticity and Enhancer Heterogeneity: Molecular Causes, Consequences and Clinical Implications.

Prostate cancer (PCa) proliferation is dictated by androgen receptor (AR) signaling, which regulates gene expression through cis-regulatory regions including proximal and distal enhancers. The repertoire of AR interactions at enhancers is dependent on tissue and cellular contexts and thus shape a spectrum of phenotypes through such epigenetic heterogeneity. Moreover, PCa is a multifocal disease and displays a high degree of intra- and inter-tumor heterogeneity, adding to the phenotypic complexity. It is increasingly becoming clear that PCa may be considered an epigenetic disease caused by various molecular causes with profound consequences and clinical implications which are underpinned by enhancer interaction heterogeneity.In this review, we provide a detailed overview of molecular interactors that affect prostate cancer epigenetic heterogeneity, such as coding and non-coding somatic variants, large scale structural variations, pioneer factor binding at enhancers and various contexts that influence enhancer engagement heterogeneity in PCa development and progression. Finally, we explore how the vast heterogeneity in epigenetic profiles identified in recent omics studies results in distinct genomic subtypes which predict disease progression and thus offer opportunities in biomarker discovery and further personalizing cancer treatment. As such, heterogeneous enhancer interactions take center stage in elucidating mechanisms of prostate cancer progression, patient prognostication, therapy discovery and overcoming acquired treatment resistance.

Abstract 4285: p66Shc/ROS enhances the progression of androgen-sensitive towards castration-resistant prostate cancer cells

Abstract Purpose and Background: Prostate cancer (PCa) is the second leading cause of cancer-related death in United States men. Androgen deprivation therapy is the standard-of-care treatment for metastatic PCa; most patients eventually relapse and develop castration-resistant (CR) tumors that currently have no effective treatment. Thus, a useful cell model for analysis of the molecular mechanism of PCa progression is required for developing targeted therapies for CR PCa. In this study, we established a PCa cell progressive model in three independent cell lines, of which androgen-independent (AI) cells were derived from respective androgen-sensitive (AS) cells, recapitulating clinical PCa progression. Experimental Methods: AS and AI human prostate adenocarcinoma cell lines LNCaP, MDA PCa2b and VCaP were utilized in this study to demonstrate the molecular and signaling alterations seen in CR PCa. Stable p66Shc cDNA transfected subclones were established from LNCaP-AS cells. The tumorigenicity of AS and AI cells as well as AS PCa cells treated with H2O2 and NAC were evaluated via trypan blue exclusion, transwell migration, clonogenic assays and xenograft mouse models. The signaling profiles including phosphoprotein microarray and immunoblotting were conducted. Results: AI PCa cells have enhanced tumorigenicity, recapitulating the clinical CR phenotype, including AR expression, proliferation and tumorigenicity under androgen-deprived conditions. Further, AI cells exhibit increased ROS levels as well as enhanced signaling of proliferation and survival pathways. We further identified oxidase p66Shc as one of the potential sources of the ROS-mediated phenotypic and cell signaling alterations in AI PCa cells. LNCaP-AI cells and p66Shc subclones have a greater oxidative environment compared to LNCaP-AS cells. Increased ROS via H2O2 enhanced AS cell growth and migration, which was counteracted by antioxidant NAC. Treatment of LNCaP-AS cells with H2O2 resulted in a similar signaling profile to that of LNCaP-AI or p66Shc subclone cells. Further, the ROS-driven alterations of p66Shc subclone cell signaling can be mitigated via p66Shc knockdown or inactive p66Shc mutant. Moreover, LNCaP-AI cells and p66Shc subclones, but not LNCaP-AS cells, develop xenograft tumors with metastatic nodules. Molecular profiling showed that alterations of signaling in LNCaP-AI cells and p66Shc subclones attributed to p66Shc/ROS. Conclusions: We report the establishment of a PCa cell progression model in three commonly used PCa cell lines that replicates clinical PCa progression from the AS to the AI/CR phenotype. Altogether, the data shows ROS produced by p66Shc promotes PCa tumorigenicity and progression to the CR phenotype. Further characterization of the PCa progressive model will aid in the understanding of advanced PCa progression to help in treatment of this lethal disease. Citation Format: Dannah Miller, Matthew Ingersoll, Arpita Chatterjee, Rebecca Oberley-Deegan, Ming-Fong Lin. p66Shc/ROS enhances the progression of androgen-sensitive towards castration-resistant prostate 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 4285.

Development and validation of lncRNAs-based nomogram for prediction of biochemical recurrence in prostate cancer by bioinformatics analysis.

Background: Early biochemical recurrence (BCR) was considered as a sign for clinical recurrence and metastasis of prostate cancer (PCa). The purpose of the present study was to identify a lncRNA-based nomogram that can predict BCR of PCa accurately.Materials and methods: Bioinformatics analysis, such as propensity score matching (PSM) and differentially expressed genes (DEGs) analyses were used to identify candidate lncRNAs for further bioinformatics analysis. LASSO Cox regression model was used to select the most significant prognostic lncRNAs and construct the lncRNAs signature for predicting BCR in discovery set. Additionally, a nomogram based on our lncRNAs signature was also formulated. Both lncRNAs signature and nomogram were validated in test set. GSEA was carried out to identify various gene sets which share a common biological function, chromosomal location, or regulation.Results: A total of 457 patients with sufficient BCR information were included in our analysis. Finally, a five lncRNAs signature significantly associated with BCR was identified in discovery set (HR=0.44, 95%CI: 0.27-0.72, C-index = 0.63) and validated in test set (HR=0.22, 95%CI: 0.09-0.56, C-index = 0.65). Additionally, the lncRNAs-based nomogram showed significant performance for predicting BCR in both discovery set (C-index = 0.74) and test set (C-index = 0.78).Conclusion: In conclusion, our lncRNAs-based nomogram is a reliable prognostic tool for BCR in PCa patients. In addition, the present study put forward the direction for the further investigation on the mechanism of PCa progression.

High OGT activity is essential for MYC-driven proliferation of prostate cancer cells.

O-GlcNAc transferase (OGT) is overexpressed in aggressive prostate cancer. OGT modifies intra-cellular proteins via single sugar conjugation (O-GlcNAcylation) to alter their activity. We recently discovered the first fast-acting OGT inhibitor OSMI-2. Here, we probe the stability and function of the chromatin O-GlcNAc and identify transcription factors that coordinate with OGT to promote proliferation of prostate cancer cells.Methods: Chromatin immunoprecipitation (ChIP) coupled to sequencing (seq), formaldehyde-assisted isolation of regulatory elements, RNA-seq and reverse-phase protein arrays (RPPA) were used to study the importance of OGT for chromatin structure and transcription. Mass spectrometry, western blot, RT-qPCR, cell cycle analysis and viability assays were used to establish the role of OGT for MYC-related processes. Prostate cancer patient data profiled for both mRNA and protein levels were used to validate findings.Results: We show for the first time that OGT inhibition leads to a rapid loss of O-GlcNAc chromatin mark. O-GlcNAc ChIP-seq regions overlap with super-enhancers (SE) and MYC binding sites. OGT inhibition leads to down-regulation of SE-dependent genes. We establish the first O-GlcNAc chromatin consensus motif, which we use as a bait for mass spectrometry. By combining the proteomic data from oligonucleotide enrichment with O-GlcNAc and MYC ChIP-mass spectrometry, we identify host cell factor 1 (HCF-1) as an interaction partner of MYC. Inhibition of OGT disrupts this interaction and compromises MYC's ability to confer androgen-independent proliferation to prostate cancer cells. We show that OGT is required for MYC-mediated stabilization of mitotic proteins, including Cyclin B1, and/or the increased translation of their coding transcripts. This implies that increased expression of mRNA is not always required to achieve increased protein expression and confer aggressive phenotype. Indeed, high expression of Cyclin B1 protein has strong predictive value in prostate cancer patients (p=0.000014) while mRNA does not.Conclusions: OGT promotes SE-dependent gene expression. OGT activity is required for the interaction between MYC and HCF-1 and expression of MYC-regulated mitotic proteins. These features render OGT essential for the androgen-independent, MYC-driven proliferation of prostate cancer cells. Androgen-independency is the major mechanism of prostate cancer progression, and our study identifies OGT as an essential mediator in this process.

New developments in mechanisms of prostate cancer progression.

Prostate cancer is the most prevalent type of cancer in men. The etiology of prostate cancer development and the mechanisms underlying androgen-independent progression remains to be further investigated. There are many known targets for prostate cancer therapy including the androgen receptor (AR) axis, but resistance eventually develops in advanced disease suggesting the need to better understand mechanisms of resistance and consideration of multi-targeted therapy. Mechanisms contributing to resistance may include gene amplifications, gene mutations, AR splice variants, and changes in expression of androgen receptor co-regulatory proteins. Given the limitations of approved therapies, further study of additional potential targets is warranted. This review focuses on the roles of autophagy pathway, p62, Yes-associated protein (YAP), cancer stem cells, and epigenetics. Therapies targeting these potential mechanisms of resistance may interact with currently approved therapies either additively or synergistically. Thus, the study of combination therapy against multiple targets may be critically important to achieve more impact against lethal forms of prostate cancer resistant to all approved current therapies.

Abstract B091: Small-molecule inhibitors targeting a specific metabolic pathway for precision therapy of advanced castrate-resistant prostate cancer

Abstract Introduction: The mechanism of prostate cancer (PCa) progression to the mostly lethal, metastatic, castrate-resistant stage (mCRPC) remains generally unknown. This prevents identifying patients likely to progress to mCRPC and designing new therapies for their treatment. A transcription factor JunD is overexpressed in PCa, but not in normal prostate epithelial cells. It complexes with androgen receptor (AR) to induce spermidine/spermine acetyl transferase (SSAT) [3]. SSAT initiates polyamine oxidation that generates copious amounts of reactive oxygen species (ROS) production in polyamine-rich PCa cells. ROS activate NF-κB. NF-κB can also induce SSAT and activate AR. This sets up a feed-forward loop for PCa growth at low androgen. Here, we present one mechanism of PCa progression to CRPC as well as its invasion and metastasis that may provide predictive biomarkers to identify patients with potentially lethal PCa at an early stage. Effects of an agent that can block both AR-JunD and AR-NF-κB interactions and prevent growth of PCa cells in vitro as well as in vivo xenografts will also be presented. Method: We have used a novel microscale device to separate invading from noninvading PCa cells ex vivo in a bone microenvironment. Immunocytochemistry (ICC), proteomic and metabolomic techniques have been employed to analyze the separated cells to understand the mechanism of invasion. Gaussia luciferase reconstitution assay has been used in a high-throughput screen (HTS) to identify inhibitors of AR-JunD and AR-NF-κB interactions. State-of-the-art in vitro cell growth assay along with in vivo pharmacokinetic (PK), maximum tolerated dose (MTD) and enzalutamide-resistant CRPC cell xenograft growth in nude mice are used to optimize the lead. Summary of Unpublished Results: Immunocytochemistry (ICC) data show that in cultured enzalutamide-resistant C4-2 and -sensitive LNCaP cells as well as in some patient PCa cells, more SSAT-positive cells are in the migratory than in the stationary section of the microscale device. Metabolomic analysis show a decrease in 3-phospho-glycerate levels in C4-2 cells, suggesting a decrease in GAPDH enzymatic activity that is related to an enhanced oxidation of GAPDH protein. Our published data of screening of 27,000+ compounds from two different chemical libraries detected a single compound that specifically inhibits both AR-JunD and AR-NF-κB2 (p52) interactions. We have synthesized several of its analogs. Lead analogs inhibit growth of AR-positive C4-2 and LNCaP cells, but have little effect on the growth of AR-negative PC-3 and SSAT-silent LNCaP siSSAT cells in culture. Co-immunoprecipitation (co-IP) assay shows its efficacy in inhibiting AR-JunD and AR-p52 interactions in LNCaP cells. It has been formulated in 25% ethanol:water and administered to nude mice orally. It is well tolerated at 50 mg/kg p.o. daily for more than 28 days and has a serum Cmax of ~ 3 μM within 30 minutes and a plasma t1/2 of ~1 h after a single oral dose of 100 mg/kg. Twenty-four hours after dosing it is found in the flank tumor (1.5 ng/mg tissue; ~450 nM) and in the prostate tissues (10 ng/mg tissue; ~3 μM) in addition to liver and kidney. Its effects on the growth of C4-2 xenografts in nude mice will be presented. Conclusion: A mechanism of PCa progression to CRPC and then to mCRPC provides a rational basis for targeted drug design that prevents PCa progression and metastasis. This should open up a new avenue of precision therapy of potentially lethal PCa at an early stage. Citation Format: Hirak Basu, Nathaniel Wilganowski, Jessica Lieblich, Grace Wu, Izabela Fokt, Sumankalai Ramachandran, Jiaquin Yu, Mark Titus, Waldemar Priebe, David J. Beebe, George Wilding. Small-molecule inhibitors targeting a specific metabolic pathway for precision therapy of advanced castrate-resistant prostate cancer [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 B091.

Abstract 1403: Modeling of Abi1 loss using spheroid cultures to investigate mechanisms of prostate tumorigenesis

Abstract American Cancer Society predicts over 160,000 new prostate cancer cases in 2017, which amounts to about 20 percent of all cancer diagnoses in men. Despite several treatment options being available, poor prognosis of high-risk and metastasis remains a major concern for prostate cancer (PCa) patients. Therefore, it is important to understand molecular mechanisms of PCa progression to aggressive disease. Our previous research identified Abelson interactor 1 (Abi1), a member of WAVE complex, as a tumor suppressor in human prostate. Not only did we find mutations and deletions in the gene in prostate tumor patient samples, but WAVE complex levels were also found to be inversely correlated to disease recurrence and castration resistance. Moreover, Abi1 is downregulated in majority of prostate cancer cell lines, and patient organoid cultures derived from metastatic bone and lymph node biopsies. These data point to the clinical significance of defining Abi1-dependent tumor suppression mechanisms. To understand these mechanisms we generated CRISPR-mediated Abi1 KO in the RWPE-1 non-tumor human prostate cell line. When plated in 3D cultures in matrigel, we observed striking phenotypic differences in the appearance and behavior of the Abi1 KO spheroids compared to the parental cells. While the parental RWPE-1 grew into spherical organoids with tight cell-cell boundaries, the Abi1 KO cells grew as loose irregular-shaped spheres, with many cells migrating out of the organoids. Hence, the loss of Abi1 in these non-tumor cells lead to gain of an invasive phenotype. Western Blots of Abi1-KO cells demonstrated concurrent disruption of WAVE complex and deregulation of WAVE complex protein levels. Moreover, cell-cell adhesion proteins such as E-cadherin and β-catenin showed modest decrease and/or a substantial loss of membrane localization. Rescue experiments of Abi1 re-expression in the KO cells reversed the phenotype indicating that the observed phenotype is Abi1-dependent. Analyses of RNA sequencing of cells obtained from 3D cultures demonstrated differences in expression signatures characteristic of altered cell-cell and cell-matrix adhesion pathways and indicated upregulation of pathways associated with the invasive phenotype of cancer cells. We propose that Abi1 loss and WAVE complex deregulation represents key mediators of invasive phenotype in PCa. [Supported by NCI R01 CA161018 and NYS Department of Health Prostate Cancer Hypothesis Development RFA #1410200115] Citation Format: Disharee Das, Ming Chen, Claudia Mondragon, Dawn Post, Alexander Nappi, Heidi Hehnly, Anita Hryniewicz-Jankowska, Pier Paolo Pandolfi, Gennady Bratslavsky, Leszek Kotula. Modeling of Abi1 loss using spheroid cultures to investigate mechanisms of prostate tumorigenesis [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 1403.

SNHG1 lncRNA negatively regulates miR-199a-3p to enhance CDK7 expression and promote cell proliferation in prostate cancer

Long noncoding RNAs (lncRNAs) have been reported to play vital roles in the development of human cancers, but our understandings of most lncRNAs in cancers are still limited. Recently, accumlating evidences have showed that many RNA transcripts could function as competing endogenous RNAs (ceRNAs) by competitively binding common microRNAs. In this study, we demonstrated that a lncRNA, Small Nucleolar RNA Host Gene 1 (SNHG1), as a ceRNA for miR-199a-3p, played a critical role in prostate cancer cell proliferation. We found that SNHG1 was aberrantly up-regulated in prostate carcinoma tissues; while, miR-199a-3p was abnormally down-regulated. The level of SNHG1 in prostate cancer was significantly negatively correlated with that of miR-199a-3p. Our data indicated that SNHG1 could interact with miR-199a-3p and inhibit the activity of miR-199a-3p in prostate cancer cells. In addition, miR-199a-3p could target the 3′ UTR of CDK7 and suppress CDK7 expression. More importantly, SNHG1 increased CDK7 expression by competitively binding miR-199a-3p, and then promoted cell proliferation and cell cycle progression in prostate cancer. Taken together, these findings elucidated a novel mechanism of prostate cancer progression. Thus, SNHG1 might serve as a potential target for prostate cancer therapies.

Comparative Proteomics Uncovers Correlated Signaling Network and Potential Biomarkers for Progression of Prostate Cancer

Background/Aims: Prostate cancer is one of the most common cancers for males worldwide, and it is prone to show the metastatic foci in lymph node and bone with high mortality. To date, the potential mechanism and the corresponding biomarkers for metastatic prostate cancer are still lacking. Hence, our study aims to clarify the mechanism of prostate cancer progression and identify the useful biomarkers for metastatic prostate cancer. Methods: The proteins and network tightly associated with tumor metastasis were identified using quantitative proteomics. Furthermore, the mRNA level of differential expressed proteins were confirmed using qRT-PCR, and the functional cluster analysis was performed using String and Cytoscape. Results: Totally, our study identified 203 differential proteins closely associated with tumor cell migration, and the mRNA expression of those proteins were verified by qPCR. Moreover, the migration associated molecular network was established using bioinformatics analysis. Conclusion: These data raveled the critical proteins for the cell migration of prostate cancer, and identified the potential markers for diagnosing the metastasis of prostate cancer.

Glyoxalase 2 Is Involved in Human Prostate Cancer Progression as Part of a Mechanism Driven By PTEN/PI3K/AKT/mTOR Signaling With Involvement of PKM2 and ERα.

Glyoxalase 2 (Glo2), together with glyoxalase 1 (Glo1), forms the main scavenging system of methylglyoxal, a potent pro-apoptotic agent mainly generated by glycolysis. An increased rate of glycolysis is a well known signature of cancer cells. As a survival strategy, Glo1 is overexpressed in many human malignant cells, including prostate cancer (PCa), where it plays a crucial role in progression. No information is available on the role of Glo2 in the same ambit. PCa is the most common malignancy affecting men in the western world. Progression to a lethal hormone-refractory PCa represents the major concern in this pathology. Therefore, a deeper understanding of the molecular mechanisms underlying PCa invasiveness and metastasis is urgently needed in order to develop novel therapeutic targets for this incurable state of the malignancy. Glo2 and Glo1 expression was examined in clinical samples of PCa by immunohistochemistry and in different PCa cell models by western blotting and quantitative real-time polymerase chain reaction. Gene silencing/overexpression and scavenging/inhibitory agents were used for functional analyses. We demonstrated that Glo2, together with Glo1, represents a novel mechanism in PCa progression as part of a pathway driven by PTEN/PI3K/AKT/mTOR signaling with involvement of PKM2 and ERα. Importantly, Glo1/Glo2 silencing did not alter the behavior of benign cells. Targeting glyoxalases metabolic pathway may represent a strategy to selectively inhibit advanced PCa. Prostate 77:196-210, 2017. © 2016 Wiley Periodicals, Inc.

Androgen-induced miR-27A acted as a tumor suppressor by targeting MAP2K4 and mediated prostate cancer progression

Prostate cancer (PCa) is the most commonly diagnosed and secondly leading cause of cancer death among males. But the precise mechanism of prostate cancer progression, including microRNAs (miRNAs) functioning in it, is still needs further study. We found miR-27a to be down-regulated in prostate cancer, and we investigated the mechanism and role of miRNA-27a in prostate cancer. MiR-27a, a transcriptional target of AR, was an androgen-induced miRNA in LNCaP cells. In castration-resistant prostate cancer (CRPC) cells, we for the first time reported that miR-27a was downregulated by PI3K signaling. MiR-27a functioned as a tumor suppressor in prostate cancer. Over-expression of miR-27a decreased prostate cancer cell proliferation and migration, and induced prostate cancer cell cycle arrest and apoptosis. MAP2K4, miR-27a’s direct target gene, functioned as an oncogene in prostate cancer by reducing G1-S phase arrest and inhibiting cell apoptosis of prostate cancer cells. In conclusion, miR-27a functions as a tumor suppressor by suppressing MAP2K4 which acts as an oncogene in prostate cancer cell lines; we also provided a new mechanism of castration-resistant prostate cancer mediated by miR-27a that downregulation of miR-27a caused by aberrant AR signaling and PI3K/Akt signaling after androgen deprivation therapy (ADT) would promote the progression of castration-resistant prostate cancer.

Abstract 1568: The role of CCL2 CCL17 CCL22-CCR4 axis in prostate cancer metastasis

Abstract BACKGROUND: Multiple steps and factors are involved in prostate carcinogenesis and tumor progression. The early studies have found that tumor-associated macrophages (TAMs) have great effects on tumor developments. TAMs release a variety of cytokines, and chemokines enabling cancer cells to proliferate, migrate, invade, and metastasize. Some chemokines and their receptors were reported to play a key role during these processes of prostate cancer. Prostate cancer cells themselves also have been shown to express various chemokines and their receptors, such as CCL2, CCR2, CXCR4. Recently, CCR4 has been reported to be expressed in breast cancer cells and is associated with lung metastasis. However, the possible role of CCR4 in prostate cancer has not been well elucidated, and little is known about the relationship between TAMs and CCL2/CCL17/CCL22-CCR4 axis in tumor invasion of prostate cancer. AIM: The aim of our study was to investigate whether TAMs and the chemokine CCL2 (a low-affinity ligand for CCR4 and a high-affinity ligand for CCR2), CCL17 and CCL22 (high-affinity ligands for CCR4) -CCR4 axis promotes prostate cancer progression. METHODS: Human prostate cancer cell lines and monocyte cell lines were used in this study. To evaluate effects of chemokines on prostate cancer cells, we performed transwell migration and invasion assay co-cultured with or without macrophages. PCR, western blot, immunocytochemistry, immunohistochemistry, human chemokine array, ELISA were done to elucidate the mechanisms of prostate cancer progression caused by macrophages. RESULTS: Chemokine receptor CCR2 and CCR4 were expressed in human prostate cancer cell lines both in mRNA and protein level. Prostate cancer tissue also expressed both CCR2 and CCR4. In vitro co-culture system of prostate cancer cell lines and macrophages showed that the level of chemokine CCL2 from both prostate cancer cell lines and macrophages was increased and chemokine receptor CCR2 and CCR4 expressions were increased in prostate cancer cell lines. They promoted the migration and invasion of prostate cancer cell lines via their receptors and also enhanced phosphorylation of protein kinase Akt and extracellular signal-regulated kinase (ERK). Our results suggested that CCL2/CCL17/CCL22-CCR4 axis might play an important role in prostate cancer progression. CONCLUSION: We demonstrate that chemokine receptor CCR2 and CCR4, for the first time, were expressed by prostate cancer cell lines. CCL2/CCL17/CCL22-CCR4 axis, which is activated by TAMs, may be a potential candidate for molecular targeted therapy in the future. Citation Format: Aerken Maolake, Kouji Izumi, Ariunbold Natsagdorji, Hiroaki Iwamoto, Atsushi Mizokami. The role of CCL2 CCL17 CCL22-CCR4 axis in prostate cancer metastasis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1568.