Androgen-dependent Prostate Cancer Cell Line Research Articles

Abstract 5695: miR-5787 suppresses cancer cell growth as a Fe3O4-nanoparticles induced pivotal miRNA

Abstract Nanotechnology offers great potential for cancer diagnosis and treatments. Especially, nanoparticles (NPs) have been examined and utilized as drug delivery systems, hyperthermia and combination therapy. We have examined and reported the combined effects of Fe3O4-nanoparticles (Fe3O4-NPs) with chemotherapeutic agents on prostate cancer cell in vitro. miRNAs are an important factor in cancer progression, and elucidating the miRNA-mediated intracellular network of cancer cells could suggest new cancer treatment strategies. In this study, to identify microRNAs (miRNAs) associated with anticancer effects of Fe3O4-NPs, the comprehensive expression of miRNAs by Microarray (Agilent G4780A SuperPrint G3 Human v16 miRNA 8x60K Microarray kit) in A549 (lung cancer cell line), LNCaP (androgen-dependent prostate cancer cell line) and DU145 (androgen-independent prostate cancer cell line) under Fe3O4-NPs exposure was performed. miR-5787 was one of the increased miRNAs in three cancer cell lines under Fe3O4-NPs, and its increase in miR-5787 was due to the reactive oxygen species (ROS) production by Fe3O4-NPs. The additional analysis suggested that miR-5787 might suppressed the cancer cell growth by targeting the eIF5. In this study, we identified miR5787 as a Fe3O4-NPs induced pivotal miRNA in cancer cells, and can be used as a therapeutic target. Citation Format: Masatoshi Watanabe, Hitoshi Nakano, Chise Matsuda, Eri Usugi, Hiroshi Imai, Yoshifumi Hirokawa, Kazutoshi Iijima. miR-5787 suppresses cancer cell growth as a Fe3O4-nanoparticles induced pivotal miRNA [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 5695.

New mode of action of curcumin on prostate cancer cells: Modulation of endoplasmic reticulum-associated degradation mechanism and estrogenic signaling.

Prostate cancer is leading to cancer-related mortality in numerous men each year worldwide. While there are several treatment options, acquired drug resistance mostly limits the success of treatments. Therefore, there is a need for the development of innovative treatments. Curcumin is one of the bioactive polyphenolic ingredients identified in turmeric and has numerous biological activities, such as anti-inflammatory and anticancer. In the present study, we investigated the effect of curcumin on the ER-associated degradation (ERAD) and estrogenic signaling in prostate cancer cells. The antiproliferative effect of curcumin on human androgen-dependent prostate cancer cell lines LNCaP and VCaP was estimated by WST-1 assay. Morphological alterations were investigated with an inverted microscope. We investigated the effect of curcumin on ERAD and estrogen signaling proteins by immunoblotting assay. To evaluate the impact of curcumin on endoplasmic reticulum (ER) protein quality-related, the expression level of 32 genes was analyzed by quantitative reverse transcription polymerase chain reaction. The nuclear translocation of estrogen receptor was examined by nuclear fractionation and immunofluorescence microscopy. We found that curcumin effectively reduced the proliferation rates of LNCaP and VCaP cells. ERAD proteins; Hrd1, gp78, p97/VCP, Ufd1 and Npl4 were strongly induced by curcumin. Also, the steady-state level of polyubiquitin was increased in a dose-dependent manner in both cell lines. Curcumin administration remarkably decreased the protein levels of estrogen receptor-alfa (Erα), whereas estrogen receptor-beta unaffected. Additionally, curcumin strongly restricted the nuclear translocation of Erα. Present data suggest that curcumin may be effectively used in therapeutic approaches associated with the targeting ER protein quality control mechanism and modulation of estrogen signaling in prostate cancer.

Integrative analysis of transcriptomic and metabolomic profiles reveals enhanced arginine metabolism in androgen-independent prostate cancer cells

BackgroundProstate cancer is a common solid tumor that affects a significant number of men worldwide. Conventional androgen deprivation therapy (ADT) increases the risk of developing castration-resistant prostate cancer (CRPC). Effective clinical management of patients with CRPC is challenging due to the limited understanding.MethodsIn this study, transcriptomic and metabolomic profiles of androgen-dependent prostate cancer cell line LNCaP and the androgen-independent cells developed from LNCaP cells (LNCaP-ADR) were investigated using RNA-sequencing and LC-MS/MS, respectively. The differentially expressed genes and metabolites were analyzed, and integrative analysis of transcriptomic and metabolomic data was further conducted to obtain a comprehensive understanding of the metabolic characteristics in LNCaP-ADR cells. Quantitative real-time PCR (QPCR) was employed to ascertain the mRNA expression levels of the selected differentially expressed genes.ResultsThe arginine and proline metabolism pathway was identified as a commonly altered pathway at both the transcriptional and metabolic levels. In the LNCaP-ADR cells, significant upregulation was observed for metabolites including 5-Aminopentanoic acid, L-Arginine, L-Glutamic acid, N-Acetyl-L-alanine, and Pyrrole-2-carboxylic acid at the metabolic level. At the transcriptional level, MAOA, ALDH3A2, ALDH2, ARG1, CKMT2, and CNDP1 were found to be significantly upregulated in the LNCaP-ADR cells. Gene set enrichment analysis (GSEA) identified various enriched gene sets in the LNCaP-ADR cells, encompassing inflammatory response, 9plus2 motile cilium, motile cilium, ciliary plasm, cilium or flagellum-dependent cell motility, cilium movement, cilium, response to endoplasmic reticulum stress, PTEN DN.V1 DN, SRC UP.V1 UP, IL15 UP.V1 DN, RB DN.V1 DN, AKT UP MTOR DN.V1 UP, VEGF A UP.V1 UP, and KRAS.LUNG.BREAST UP.V1 UP.ConclusionsThese findings highlight the substantial association between the arginine and proline metabolism pathway and CRPC, emphasizing the need to prioritize strategies that target dysregulated metabolites and differentially expressed genes as essential interventions in the clinical management of CRPC.

Antiproliferative, apoptosis-inducing, and GSTP1 demethylation activities of Ellagitannins isolated from Cornus alba L.

This study aimed to prove the prostate cancer chemopreventive activity of compounds isolated from CA. We evaluated these compounds using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and evaluated their NF-κB inhibitory activity and apoptosis-inducing activity using western blot analysis and flow cytometry, respectively. Their DNA methylation activity was also evaluated via a methylation-specific polymerase chain reaction in androgen-dependent (LNCaP) and androgen-independent (PC-3) prostate cancer cell lines. Camptothin B (1), cornusiin B (2), and cornusiin A (3), which were isolated in our previous work, relatively reduced the protein expression levels in PCa cells. Among them, cornusiin B (2) exhibited excellent NF-κB inhibitory activity. Also, concentration-dependently increased the unmethylated DNA content and decreased the methylated DNA content in both PC-3 and LNCaP cells. Therefore, cornusiin B (2), which was isolated from CA, has the potential to act as a chemopreventive agent for prostate cancer.

Androgen receptor signaling-mitochondrial DNA-oxidative phosphorylation: A critical triangle in early prostate cancer.

Mitochondria are more than just the cellular powerhouse. They also play key roles in vital functions such as apoptosis, metabolism regulation, and other intracellular interactions. The mitochondrial DNA (mtDNA) encodes for 12 subunits of the oxidative phosphorylation (OXPHOS) system. Depletion of mtDNA in androgen-dependent prostate cancer (PCa) cell lines renders them androgen-independent and more aggressive. Paradoxically, pharmaceutical inhibition of OXPHOS is lethal for subsets of PCa cells, whereas others become dependent on androgen receptor (AR) signaling for survival. Given that the AR-mitochondria interaction is critical for early PCa, it is crucial to understand the details of this interaction. Technical hurdles have made mitochondria traditionally difficult to study, with many techniques used for isolation masking the properties of given individual mitochondria. Although the isolation of mitochondria enables us to study OXPHOS, we miss the context in which mitochondria interact with the rest of the cell. Both AR signaling and mtDNA affect apoptosis, metabolism regulation, cellular calcium storage and homeostasis, intracellular calcium signaling, and redox homeostasis. In this review, we will attempt to understand how the crosstalk between AR-mtDNA-OXPHOS is responsible for "life or death" decisions inside the cells. Our aim is to point toward potential vulnerabilities that can lead to the discovery of novel therapeutic targets.

Abstract 651: Combination of the androgen receptor inhibitor darolutamide and the PI3K inhibitor copanlisib leads to improved anti-tumor efficacy and apoptosis in prostate cancer models

Abstract Prostate cancer is mainly driven by androgen receptor (AR) signaling so that drugs directly inhibiting this pathway such as GnRH ligands and AR inhibitors are now established as mainstay treatments. Unfortunately, treatment resistance often develops and combination therapies may represent potential strategies to prolong disease remission. The PI3K/Akt/mTOR signaling pathway plays an essential role in prostate cancer and is upregulated in about 30-50% of patients. Loss of the PI3K/Akt/mTOR pathway inhibitor PTEN is observed in up to 40% of late-stage prostate cancer patients. Compounds inhibiting PI3K or Akt have shown promising efficacy in preclinical prostate cancer models, and advanced clinical trials with these inhibitors are currently ongoing in metastatic castration-resistant prostate cancer, often in combination with AR inhibitors. Here we examined the impact of combining the AR inhibitor darolutamide with the pan class I PI3K inhibitor copanlisib on preclinical models in vitro and in vivo. We found that treating different androgen-dependent prostate cancer cell lines with darolutamide and copanlisib had a very strong synergistic inhibitory effect. Induction of apoptosis was observed in the PARP cleavage and caspase 3/7 activation assays after treatment with copanlisib and more so after treatment with copanlisib plus darolutamide. Expression analysis showed that darolutamide strongly down-regulated AR target genes such as KLK3, FKBP5 and TMPRSS2, but copanlisib had no additional impact. However, when examining genes involved in the apoptotic pathway we found that the down-regulation of pro-apoptotic genes that follows androgen treatment was strongly reversed by the combined darolutamide and copanlisib treatment. Finally, in vivo efficacy studies showed that the LuCaP 96 prostate cancer patient-derived (PDX) xenograft, which has a non-functional PTEN gene, strongly responded to darolutamide, but additional treatment with copanlisib did not increase anti-tumor efficacy. In the LuCaP 35 PDX model, which expresses PTEN at low level, darolutamide or copanlisib treatment alone showed only limited efficacy, while the combination exhibited tumor inhibitory effects. In conclusion, we found that combining darolutamide with copanlisib strongly inhibited the proliferation of prostate cancer models in vitro. This was linked to strong induction of cell apoptosis and prevention of pro-apoptotic gene down-regulation. Superior efficacy was also observed in the LuCaP 35 PDX xenograft model in vivo. Additional data are needed to explore the underlying molecular mechanisms. Together these results further support the exploration of the impact of combining AR and PI3K signaling inhibitors in late-stage prostate cancer patients. Citation Format: Tatsuo Sugawara, Holly NGuyen, Eva Corey, Ekaterina Nevedomskaya, Oliver Politz, Dominik Mumberg, Bernard Haendler. Combination of the androgen receptor inhibitor darolutamide and the PI3K inhibitor copanlisib leads to improved anti-tumor efficacy and apoptosis in prostate cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 651.

Abstract 5471: PRT2527, a novel highly selective cyclin-dependent kinase 9 (CDK9) inhibitor, is active in preclinical models of prostate cancer

Abstract CDK9 is a serine/threonine kinase belonging to the subclass of the transcription associated CDKs. CDK9 complexes with cyclin T and cyclin K, the positive transcription elongation factor b (P-TEFb), and phosphorylates Serine 2 of RNA polymerase II (pSer2 RNAPII) to activate transcription. Consequently, targeting CDK9 could effectively interfere with epigenetic and transcriptional reprogramming and prevent disease progression and treatment resistance in human cancers. Androgen receptor (AR)-dependence in prostate cancer is linked to CDK9 function. CDK9 stabilizes AR-associated proteins, and pharmacological inhibition of CDK9 can inhibit AR, AR variants, and their downstream transcription programs. We evaluated the novel CDK9 inhibitor, PRT2527, in prostate cancer models to evaluate its effects on cell proliferation, stem-like tumor cells, and tumor growth. PRT2527 is a potent inhibitor of CDK9/CyclinT1 complex, and when evaluated at concentration 200 times the biochemical IC50, PRT2527 was highly selective for CDK9 inhibition. We verified in biochemical assays the ability of PRT2527 to suppress pSer2 RNAPII and reduce expression of c-Myc, a common target of CDK9, in a concentration-dependent manner in multiple human prostate cancer cell lines. PRT2527 also inhibited c-Myc-dependent transcription in vitro in luciferase reporter assays. Furthermore, RNA sequencing showed altered expression of several genes with significant enrichment of c-Myc and E2F targets and RNAPII dependent transcription among downregulated genes in PRT2527-treated VCaP cells. In vitro, PRT2527 inhibited the proliferation of androgen-dependent and androgen-independent prostate cancer cell lines (IC50, ≤50 nM). PRT2527 was highly effective (IC50, ≤10 nM) in tumor-spheroid assays in blocking the growth of stem-like tumor cells and significantly suppressed the in vitro growth of tumor organoids from both human cell lines and patient-derived xenografts (PDXs). In mice, PRT2527 IV administration reduced pSer2 RNAPII in tumor xenografts and c-Myc-dependent transcriptional activity in a DU145 luminescence reporter model. PRT2527 administration in mice significantly reduced growth of PDX LuCaP 35 (castration-sensitive, adenocarcinoma) and LuCaP 145.2 (castration-resistant, neuroendocrine) along with the fraction of tumor-initiating stem-like cells in ex vivo assays. PRT2527 reduced pSer2 RNAPII in both PDXs, whereas c-Myc decreased in LuCaP 35 and Sox2 in LuCaP 145.2, relative to basal expression levels. Collectively, our data demonstrate that PRT2527 has potent pharmacodynamic and antitumor activity in multiple models of castration-sensitive and castration-resistant prostate cancer. PRT2527 is advancing into phase 1 studies in solid tumors. Citation Format: Elisa Federici, Gianluca Civenni, Aleksandra Kokanovic, Giada Sandrini, Luca Guarrera, Simone Mosole, Alessia Cacciatore, Valeria Uboldi, Manuel Lessi, Giovanni Papa, Domenico Albino, Elisa Storelli, Jessica Merulla, Andrea Rinaldi, Marco Bolis, Yang Zhang, Kris Vaddi, Peggy Scherle, Bruce Ruggeri, Giuseppina M. Carbone, Carlo V. Catapano. PRT2527, a novel highly selective cyclin-dependent kinase 9 (CDK9) inhibitor, is active in preclinical models of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5471.

Antagonistic action of a synthetic androgen ligand mediated by chromatin remodeling in a human prostate cancer cell line

The clinical use of androgen receptor (AR) antagonists has been successful in treating prostate cancer patients, inducing remission of androgen-dependent tumors. However, a couple of years after treatment, prostate tumors transition into an androgen-independent state with altered gene expression profiles, but the molecular basis is not understood. Since the AR antagonists trigger this transition, we assessed whether AR antagonists induce chromatin reorganization in an androgen-dependent prostate cancer cell line (LNCaP). Treatment of LNCaP cells with two clinically used AR antagonists (bicalutamide [Bic] and enzalutamide [Enz]) expectedly resulted in antagonistic effects on cell proliferation, AR transactivation, and dihydrotestosterone (DHT)-induced expression of AR target genes. Thus, the antagonists expectedly acted to antagonize the transactivation function of AR activated by androgen binding. By ChIP-qPCR assay, AR bound to Bic, but not Enz, was recruited to an endogenous consensus AR-binding site within the kallikrein-related peptidase 3 gene promoter after treatment with Bic, similar to the effect of DHT. By ATAC-seq analysis of the cells after long-term treatment for 5 days, Bic and dihydrotestosterone DHT induced different chromatin reorganization patterns and gene expression profiles, suggesting that Bic exhibited a distinct action from that by DHT. Thus, these results suggest that the action of a known AR antagonist is mediated by chromatin reorganization in a prostate cancer cell line.

NK Cells Can Preferentially Target Prostate Cancer Stem-like Cells via the TRAIL/DR5 Signaling Pathway.

Background: The occurrence of androgen-dependent prostate cancer mainly depends on prostate cancer stem cells. To reduce the risk of androgen-dependent prostate cancer, the direct elimination of prostate cancer stem cells is important, but an elimination strategy has not yet been established. A previous study showed that natural killer (NK) cells can preferentially target cancer stem cells in several solid tumors except prostate cancer. In this context, this study was undertaken to investigate if NK cells can selectively attack androgen-dependent prostate cancer stem cells. Methods: Prostate cancer stem-like cells were separated from an androgen-dependent prostate cancer cell line (LNCaP) using a three-dimensional culture system. LNCaP stem-like cells or LNCaP cells were co-cultured with human NK cells (KHYG-1) for 24–72 h, and cell viability was determined using the WST-8 method. The expression of each protein in the cell membrane was evaluated through FACS analysis, and mRNA levels were determined using real-time PCR. Results: KHYG-1 cells had more potent cytotoxicity against LNCaP stem-like cells than LNCaP cells, and the potency of the cytotoxicity was strongly related to the TRAIL/DR5 cell death pathway. Conclusion: NK cells can preferentially target prostate cancer stem-like cells via the TRAIL/DR5 pathway.

Discovery of Easily Synthesizable 4, 4‐Dimethylimidazolidin‐2‐ones as Potent Androgen Receptor Antagonists for Prostate Cancer

AbstractAndrogen deprivation therapy (ADT), also known as suppression of androgen activity, is a first‐line treatment option for patients with prostate cancer (PC). ADT became ineffective after several years of treatment due to the development of castration‐resistant prostate cancer (CRPC), which resulted in more deaths in PC patients, but it is still androgen receptor (AR) dependent. Under these conditions, the U.S. Food and Drug Administration (FDA) approved enzalutamide for the treatment of patients with metastatic CRPC (mCRPC) and, more recently, nonmetastatic CRPC (nmCRPC). Despite the fact that this drug has extended overall and progression‐free survival in a wide range of CRPC patients, more research is needed to better understand the mechanisms of resistance challenges and analogues chemical lead structures as next generation AR antagonists. In this regard, we discovered simple and easily synthesizable new pharmacophore, 4,4‐dimethylimidazolidin‐2‐one, based derivatives MDV1‐MDV8 for potent AR antagonists; here, the thiohydantoin pharmacophore in enzalutamide is replaced by 4,4‐dimethylimidazolidin‐2‐one. The antiproliferative activities of these molecules have been assessed against androgen dependent PC cell line (LNCaP). The structure‐activity relationship of these molecules, as well as their relationship with enzalutamide, is investigated. Among the reported molecules, MDV4 showed significantly improved in vitro activity with the IC50 value of 780.85 nM.

Alnus sibirica Compounds Exhibiting Anti-Proliferative, Apoptosis-Inducing, and GSTP1 Demethylating Effects on Prostate Cancer Cells.

Alnus sibirica (AS) is distributed in Korea, Japan, China, and Russia and has reported anti-oxidant, anti-inflammatory, and reducing activities on atopic dermatitis-like skin lesions, along with other beneficial health properties. In the present study, we tried to prove the cancer-preventive activity against prostate cancer. The extracted and isolated compounds, oregonin (1), hirsutenone (2), and hirsutanonol (3), which were isolated from AS, were tested for anti-proliferative activity. To do this, we used the MTT assay; NF-κB inhibitory activity, using Western blotting; apoptosis-inducing activity using flow cytometry; DNA methylation activity, using methylation-specific polymerase chain reaction in androgen-dependent (LNCaP) and androgen-independent (PC-3) prostate cancer cell lines. The compounds (1–3) showed potent anti-proliferative activity against both prostate cancer cell lines. Hirsutenone (2) exhibited the strongest NF-κB inhibitory and apoptosis-inducing activities compared with oregonin (1) and hirsutanonol (3). DNA methylation activity, which was assessed for hirsutenone (2), revealed a concentration-dependent enhancement of the unmethylated DNA content and a reduction in the methylated DNA content in both PC-3 and LNCaP cells. Overall, these findings suggest that hirsutenone (2), when isolated from AS, may be a potential agent for preventing the development or progression of prostate cancer.

Receptor Tyrosine Kinase‐like Orphan Receptor 1 (ROR1) as a Selective Molecular Target in Androgen‐Dependent and Androgen‐Independent Prostate Cancer

Prostate cancer is a disease that has a high prevalence and mortality amongst men. The severity of the cancer is stratified by risk, which is based on the Gleason grade, prostate-specific antigen (PSA) level, and clinical staging. Unlike breast cancer which can be classified into subtypes based on molecular heterogeneity, prostate cancer has no such classification and is therefore treated with non-specific chemotherapy and radiation if local, and androgen deprivation therapy (ADT) if metastatic. It is of the utmost importance to investigate molecular targets that can specifically eradicate prostate cancer while retaining the functions of normal tissue. Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a receptor that is highly expressed in embryogenesis and cancer, while being minimally expressed in normal tissue. In particular, prostate cancer exhibits moderate to high levels of ROR1 expression. The goal of this study is to elucidate the role of ROR1 in aggressive prostate cancer and selectively target it for treatment. Our laboratory had previously characterized Strictinin, a ROR1 inhibitor, as being selectively cytotoxic against TNBC via inhibition of the ROR1 receptor. We hypothesize that Strictinin can reduce the proliferation and invasion of prostate cancer and may potentially serve as a specific therapeutic agent. Preliminary results indicate that Strictinin is selectively lethal to androgen-dependent and androgen-independent prostate cancer cell lines. Strictinin treatment reduced expression of proteins downstream of ROR1 implicated in promoting migration, invasion, and anti-apoptosis. Furthermore, Strictinin treatment decreased migration and invasion while inducing apoptosis in PC3 and LnCAP cell lines, providing evidence that inhibition of the ROR1 molecular pathway is linked to reduction of cancerous phenotypes. These preliminary results indicate that ROR1 could be a novel molecular target that can be utilized for subtyping and treating prostate cancer. The data from this study will establish Strictinin as a potential therapeutic that targets ROR1 to reduce migration, invasion, and survival of prostate cancer.

Cross-Resistance to Abiraterone and Enzalutamide in Castration Resistance Prostate Cancer Cellular Models Is Mediated by AR Transcriptional Reactivation.

Simple SummaryProstate cancer is the second most common cancer in males. In prostate cancer cells, androgens bind and activate the intracellular mediator called Androgen Receptor that control cell proliferation and survival. Hormone deprivation therapy is administrated to reduce androgen levels and consequently tumour growth. Unfortunately, most patients develop resistance to hormone treatment over the years and novel hormonal agents, such as Abiraterone or Enzalutamide, are administered. However, many patients do not initially respond or become resistant to these drugs quickly. Firstly, we demonstrated that in hormonal sensitive human prostate cancer cells the combination therapy of Abiraterone plus Enzalutamide reduced cell growth and survival. Moreover, starting from these prostate cancer cell lines, we generated cellular models of resistance to hormonal deprivation alone or in combination with the novel hormonal agents. In all the cases, resistant cell lines restore Androgen Receptor expression, Androgen Receptor functionality, cell proliferation and migration in the absence of androgens. Importantly, these novel cellular models acquire cross-resistance to each other. These results are consistent with clinical trials in castration resistant prostate cancer patients and suggest the biological rationale to test the combination therapy of Abiraterone plus Enzalutamide as first-line treatment in hormone-sensitive prostate cancer patients before becoming hormonal resistant.Androgen deprivation therapy (ADT) and novel hormonal agents (NHAs) (Abiraterone and Enzalutamide) are the goal standard for metastatic prostate cancer (PCa) treatment. Although ADT is initially effective, a subsequent castration resistance status (CRPC) is commonly developed. The expression of androgen receptor (AR) alternative splicing isoforms (AR-V7 and AR-V9) has been associated to CRPC. However, resistance mechanisms to novel NHAs are not yet well understood. Androgen-dependent PCa cell lines were used to generate resistant models to ADT only or in combination with Abiraterone and/or Enzalutamide (concomitant models). Functional and genetic analyses were performed for each resistance model by real-time cell monitoring assays, flow cytometry and RT-qPCR. In androgen-dependent PCa cells, the administration of Abiraterone and/or Enzalutamide as first-line treatment involved a critical inhibition of AR activity associated with a significant cell growth inhibition. Genetic analyses on ADT-resistant PCa cell lines showed that the CRPC phenotype was accompanied by overexpression of AR full-length and AR target genes, but not necessarily AR-V7 and/or AR-V9 isoforms. These ADT resistant cell lines showed higher proliferation rates, migration and invasion abilities. Importantly, ADT resistance induced cross-resistance to Abiraterone and/or Enzalutamide. Similarly, concomitant models possessed an elevated expression of AR full-length and proliferation rates and acquired cross-resistance to its alternative NHA as second-line treatment.

The lncRNA PTTG3P promotes the progression of CRPC via upregulating PTTG1

Overexpression of certain long non-coding RNAs (lncRNAs) promotes the progression of castration-resistant prostate cancer (CRPC). The significance and potential role of the lncRNA designated pituitary tumour-transforming 3, pseudogene (PTTG3P) in CRPC is unknown. We detected PTTG3P expression by qPCR. Upregulated PTTG3P expression was performed to explore the role of PTTG3P in PCa cells resistant to ADT (androgen deprivation therapy). The relationship among PTTG3P, mir-146a-3p and PTTG1 were validated by qPCR, western blot and luciferase assay. PTTG3P levels were significantly increased in the androgen-independent PC cell lines, as well as in CRPC tissues compared with those of the androgen-dependent prostate cancer cell line LNCaP and tumour tissues of patients with hormone-naive prostate cancers. Enforced expression of PTTG3P in androgen-deprived LNCaP cells significantly enhanced survival, clonogenicity, and tumorigenicity. Further, PTTG3P acted as a competing endogenous RNA (ceRNA, natural miRNA sponge) to upregulate PTTG1 expression by competing for mir-146a-3p in the progression to CRPC. Our findings suggest that PTTG3P promotes the resistance of prostate cancer cells to androgen-deprivation therapy via upregulating PTTG1. PTTG3P may therefore represent a potential target for therapy of CRPC.

Follicle-stimulating hormone promotes growth of human prostate cancer cell line-derived tumor xenografts.

Chemical castration in prostate cancer can be achieved with gonadotropin-releasing hormone (GnRH) agonists or antagonists. Their effects differ by the initial flare of gonadotropin and testosterone secretion with agonists and the immediate pituitary-testicular suppression by antagonists. While both suppress luteinizing hormone (LH) and follicle-stimulating hormone (FSH) initially, a rebound in FSH levels occurs during agonist treatment. This rebound is potentially harmful, taken the expression of FSH receptors (R) in prostate cancer tissue. We herein assessed the role of FSH in promoting the growth of androgen-independent (PC-3, DU145) and androgen-dependent (VCaP) human prostate cancer cell line xenografts in nude mice. Gonadotropins were suppressed with the GnRH antagonist degarelix, and effects of add-back human recombinant FSH were assessed on tumor growth. All tumors expressed GnRHR and FSHR, and degarelix treatment suppressed their growth. FSH supplementation reversed the degarelix-evoked suppression of PC-3 tumors, both in preventive (degarelix and FSH treatment started upon cell inoculation) and therapeutic (treatments initiated 3weeks after cell inoculation) setting. A less marked, though significant FSH effect occurred in DU145, but not in VCaP xenografts. FSHR expression in the xenografts supports direct FSH stimulation of tumor growth. Testosterone supplementation, to maintain the VCaP xenografts, apparently masked the FSH effect on their growth. Treatment with the LH analogue hCG did not affect PC-3 tumor growth despite their expression of luteinizing hormone/choriongonadotropin receptor. In conclusion, FSH, but not LH, may directly stimulate the growth of androgen-independent prostate cancer, suggesting that persistent FSH suppression upon GnRH antagonist treatment offers a therapeutic advantage over agonist.

The potent AMPK inhibitor BAY-3827 shows strong efficacy in androgen-dependent prostate cancer models.

5' adenosine monophosphate-activated kinase (AMPK) is an essential regulator of cellular energy homeostasis and has been associated with different pathologies, including cancer. Precisely defining the biological role of AMPK necessitates the availability of a potent and selective inhibitor. High-throughput screening and chemical optimization were performed to identify a novel AMPK inhibitor. Cell proliferation and mechanistic assays, as well as gene expression analysis and chromatin immunoprecipitation were used to investigate the cellular impact as well as the crosstalk between lipid metabolism and androgen signaling in prostate cancer models. Also, fatty acid turnover was determined by examining lipid droplet formation. We identified BAY-3827 as a novel and potent AMPK inhibitor with additional activity against ribosomal 6 kinase (RSK) family members. It displays strong anti-proliferative effects in androgen-dependent prostate cancer cell lines. Analysis of genes involved in AMPK signaling revealed that the expression of those encoding 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR), fatty acid synthase (FASN) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 (PFKFB2), all of which are involved in lipid metabolism, was strongly upregulated by androgen in responsive models. Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) analysis identified several androgen receptor (AR) binding peaks in the HMGCR and PFKFB2 genes. BAY-3827 strongly down-regulated the expression of lipase E (LIPE), cAMP-dependent protein kinase type II-beta regulatory subunit (PRKAR2B) and serine-threonine kinase AKT3 in responsive prostate cancer cell lines. Also, the expression of members of the carnitine palmitoyl-transferase 1 (CPT1) family was inhibited by BAY-3827, and this was paralleled by impaired lipid flux. The availability of the potent inhibitor BAY-3827 will contribute to a better understanding of the role of AMPK signaling in cancer, especially in prostate cancer.

Chemosensitizing effects of methyl jasmonate on paclitaxel-resistant androgen-dependent and independent prostate cancer cell lines

The taxane-based therapy provides survival benefit in patients with metastatic prostate cancer; however, the average survival is less than 20 months due to the partial taxane-related chemoresistance. Innovative strategies are needed to overcome the chemoresistance for improved patient survival. In this project, paclitaxel-resistance was developed on androgen-independent PC3 and androgen-dependent 22Rv1 and LNCaP human prostate cancer (PCa) cell lines to investigate the efficacy of methyl jasmonate (MeJa), an anti-cancer drug, in overcoming the chemoresistance. The PCa cell lines were maintained in RPMI-1640 medium supplemented with 10% fetal bovine serum (FBS) at 37?C under 5% CO2. The cell lines were exposed to the gradually increasing doses of paclitaxel. Since the resistance on LNCaP could not be achieved, the study was continued with 22Rv1 cell line. It was demonstrated that paclitaxel-resistant cell lines overexpress ABCB1. Resistance levels of cells and MeJa activity in all resistant and parental lines were measured using CellTiter-Glo? luminescent assay. Test results were compared with Student?s t-test or analysis of variance (ANOVA). P?0.05 (two-tailed) was considered to be significant. In conclusion, MeJa showed more cytotoxicity on paclitaxel resistant PC3 (PC3-PtxR) cells than resistant 22Rv1 (22Rv1-PtxR) cells. Detection of cytotoxic effects of MeJa in overcoming paclitaxel resistance may contribute to the development of alternative new compounds for the prevention or chemosensitization of resistance to chemotherapeutics such as paclitaxel.

Abstract 4102: Genome-wide CRISPRa screen reveals new drivers of Enzalutamide resistance in prostate cancer

Abstract Potent anti-androgens such as Enzalutamide (Enza) have been approved for the treatment of mCRPC. Despite initial response, nearly all patients eventually develop resistance to Enza. Although a few mechanisms of Enza resistance have been identified, none have been translated into a clinical benefit for recurrent patients. Our goal is to identify new therapeutic targets to overcome Enza resistance. We performed a genome-wide CRISPR activation screen using deactivated Cas9 (dCas9) fused to VP64 transcriptional activator in the androgen-dependent prostate cancer cell line (LNCaP). We used the Calabrese sgRNA library which targets 18,885 genes using 3 different sgRNAs per gene (56,762 sgRNAs). Cells expressing the gRNA library were treated with Enza (20µM) for 7 weeks to allow for enrichment of potential resistance genes. We identified 10 genes which were targeted by at least 2 sgRNAs with a Fold Change (FC) > 4 in the Enza vs control group. Notably, AR was the most enriched gene. AR up-regulation is one of the main drivers of Enza resistance in patients. Pathway enrichment analysis using all the sgRNAs with FC> 5 revealed an over-representation of the RB1, TP53 and TGF-β pathways. Importantly, these pathways are also known to drive Enza resistance. Our screen also identified new candidate genes that have never been linked to Enza resistance. Interestingly, most of these genes are transcription factors. We validated the screen results in vitro. Further analysis of this target genes in vitro and in vivo will allow us to identify novel genes and potential therapeutic targets for Enza resistance. Citation Format: Yara Rodriguez, Rajita Vatapalli, Huyin Han, Kenji Unno, Vinay Sagar, Zachary Chalmers, Barbara Lysy, Young A Yoo, Mihai Truica, Sarki Abdulkadir. Genome-wide CRISPRa screen reveals new drivers of Enzalutamide resistance in prostate cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4102.

Isorhamnetin inhibited the proliferation and metastasis of androgen-independent prostate cancer cells by targeting the mitochondrion-dependent intrinsic apoptotic and PI3K/Akt/mTOR pathway.

The present study investigated the effects of Isorhamnetin on two types of prostate cancer cells (androgen-independent and androgen-dependent) and explored its possible mechanisms underlying such effects. Treatment with Isorhamnetin significantly inhibited cell growth and induced lactate dehydrogenase (LDH) release of androgen-independent DU145 and PC3 prostate cancer cells, but exhibited almost no toxicity effect on androgen-dependent LNCaP prostate cancer cell line or normal human prostate epithelial PrEC cells, which was achieved by the induction of apoptosis in a mitochondrion-dependent intrinsic apoptotic pathway. Furthermore, Isorhamnetin inhibited cell migration and invasion in concentration-dependent manners by enhancing mesenchymal−epithelial transition (MET) and inhibiting matrix metalloproteinase (MMP) 2 (MMP-2) and MMP-9 overexpression. In addition, Isorhamnetin also down-regulated the expression of phosphorylated PI3K (p-P13K), Akt (p-Akt), and mTOR (p-mTOR) proteins in both cancer cells, revealing Isorhamnetin to be a selective PI3K–Akt–mTOR pathway inhibitor. In summary, these findings propose that Isorhamnetin might be a novel therapeutic candidate for the treatment of androgen-independent prostate cancer.

Stevia eupatoria and Stevia pilosa Extracts Inhibit the Proliferation and Migration of Prostate Cancer Cells.

Background and Objectives: Prostate cancer is the second most harmful disease in men worldwide and the number of cases is increasing. Therefore, new natural agents with anticancer potential should be examined and the response of existing therapeutic drugs must be enhanced. Stevia pilosa and Stevia eupatoria are two species that have been widely used in traditional medicine, but their effectiveness on cancer cells and their interaction with antineoplastic drugs have not been studied. The aim of this study was to evaluate the anticancer activity of Stevia pilosa methanolic root extract (SPME) and Stevia eupatoria methanolic root extract (SEME) and their effect, combined with enzalutamide, on prostate cancer cells. Materials and Methods: The study was conducted on a human fibroblast cell line, and on androgen-dependent (LNCaP) and androgen-independent (PC-3) prostate cancer cell lines. The cell viability was evaluated using a Trypan Blue exclusion test for 48 h, and the migration by a wound-healing assay for 24, 48, and 72 h. Results: The results indicate that SPME and SEME were not cytotoxic at concentrations less than 1000 μg/mL in the human fibroblasts. SPME and SEME significantly reduced the viability and migration of prostate cancer cells in all concentrations evaluated. The antiproliferative effect of the Stevia extracts was higher in cancer cells than in normal cells. The enzalutamide decreased the cell viability in all concentrations tested (10–50 µM). The combination of the Stevia extracts and enzalutamide produced a greater effect on the inhibition of the proliferation and migration of cancer cells than the Stevia extracts alone, but not of the enzalutamide alone. Conclusion: The results indicate that SPME and SEME have an inhibitory effect on the viability and migration of prostate cancer cells and do not interfere with the enzalutamide anticancer effect. The data suggest that Stevia extracts may be a potential source of molecules for cancer treatment.