Castration-resistant Prostate Cancer Progression Research Articles

The kinesin KIF20A promotes progression to castration-resistant prostate cancer through autocrine activation of the androgen receptor.

Prostate cancer that recurs following androgen-deprivation therapy is termed castration-resistant, which is incurable and is marked by reactivation of androgen receptor (AR) signaling. KIF20A, a kinesin with unique structural features, is overexpressed in human castration-resistant prostate cancer (CRPC) compared to androgen-dependent PC and benign tissue. KIF20A has well-described roles in mitotic processes, but it has a less characterized function in vesicle fission and trafficking within Golgi-driven secretory pathways. Stable expression of KIF20A in androgen-dependent PC cells promoted progression to CRPC through the activation of AR signaling in vitro and in vivo. KIF20A expression resulted in the secretion of autocrine factors in the conditioned media that activated AR and caused castration-resistant proliferation of naïve androgen-dependent cells. Pharmacologic disruption of vesicle biogenesis blocked KIF20A-driven castration-resistant proliferation of androgen-dependent PC. KIF20A depletion or treatment with the KIF20A-specific inhibitor, paprotrain, reduced CRPC . These data are the first to establish KIF20A as a driver of CRPC progression through AR activation and as a promising therapeutic target against CRPC.

PPFIA4 promotes castration-resistant prostate cancer by enhancing mitochondrial metabolism through MTHFD2

BackgroundThe development of castration-resistant prostate cancer (CRPC) remains a major obstacle in the treatment of prostate cancer (PCa). Dysregulated mitochondrial function has been linked to the initiation and progression of diverse human cancers. Deciphering the novel molecular mechanisms underlying mitochondrial function may provide important insights for developing novel therapeutics for CRPC.MethodsWe investigate the expression of the protein tyrosine phosphatase receptor type F polypeptide interacting protein alpha 4 (PPFIA4) using public datasets and tumor specimens from PCa cases by immunohistochemistry. Gain- and loss-of-function studies are performed in PCa cell lines and mouse models of subcutaneous xenograft to characterize the role of PPFIA4 in CRPC. Gene expression regulation is evaluated by a series of molecular and biochemical experiments in PCa cell lines. The therapeutic effects of methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) inhibitor combined enzalutamide are assessed using in vitro functional assays and in vivo mouse models.ResultsWe show that the increase of PPFIA4 exacerbates aggressive phenotype resembling CRPC. A fraction of PPFIA4 localizes to mitochondria and interacts with MTHFD2, a key enzyme for one-carbon metabolism. Androgen deprivation increases the translocation of PPFIA4 into mitochondria and increases the interaction between PPFIA4 and MTHFD2, which result in the elevation of tyrosine phosphorylated MTHFD2. Consequently, the levels of NADPH synthesis increase, resulting in protection against androgen deprivation-induced mitochondrial dysfunction, as well as promotion of tumor growth. Clinically, PPFIA4 expression is significantly increased in CRPC tissues compared with localized PCa ones. Importantly, an MTHFD2 inhibitor, DS18561882, combined with enzalutamide can significantly inhibit CRPC cell proliferation in vitro and tumor growth in vivo.ConclusionOverall, our findings reveal a PPFIA4-MTHFD2 complex in mitochondria that links androgen deprivation to mitochondrial metabolism and mitochondrial dysfunction, which suggest a potential strategy to inhibit CRPC progression.

Comprehensive genomics in androgen receptor-dependent castration-resistant prostate cancer identifies an adaptation pathway mediated by opioid receptor kappa 1

Castration resistance is a lethal form of treatment failure of prostate cancer (PCa) and is associated with ligand-independent activation of the androgen receptor (AR). It is only partially understood how the AR mediates survival and castration-resistant growth of PCa upon androgen deprivation. We investigated integrative genomics using a patient-derived xenograft model recapitulating acquired, AR-dependent castration-resistant PCa (CRPC). Sequencing of chromatin immunoprecipitation using an anti-AR antibody (AR-ChIP seq) revealed distinct profiles of AR binding site (ARBS) in androgen-dependent and castration-resistant xenograft tumors compared with those previously reported based on human PCa cells or tumor tissues. An integrative genetic analysis identified several AR-target genes associated with CRPC progression including OPRK1, which harbors ARBS and was upregulated upon androgen deprivation. Loss of function of OPRK1 retarded the acquisition of castration resistance and inhibited castration-resistant growth of PCa both in vitro and in vivo. Immunohistochemical analysis showed that expression of OPRK1, a G protein-coupled receptor, was upregulated in human prostate cancer tissues after preoperative androgen derivation or CRPC progression. These data suggest that OPRK1 is involved in post-castration survival and cellular adaptation process toward castration-resistant progression of PCa, accelerating the clinical implementation of ORPK1-targeting therapy in the management of this lethal disease.

Patchouli alcohol suppresses castration-resistant prostate cancer progression by inhibiting NF-κB signal pathways.

BackgroundThere is evidence that patchouli alcohol (PA) has cytotoxic effects on human cancer cell lines, including inhibiting cell growth, migration, and invasion. However, the exact molecular mechanism of PA in human castration-resistant prostate cancer (CRPC) cells remains unclear.MethodsDU145 and PC-3 cells were treated with different concentrations of PA for 48 h. Cell counting kit-8 (CCK-8), colony formation, and 5-ethynyl-2'-deoxyuridine (EdU) staining were used to detect cell proliferation. Scratch tests and transwell assays were used to detect cell migration and invasion. TdT-mediated dUTP nick-end labeling (TUNEL) staining and flow cytometry were performed to examine apoptosis and mitochondrial membrane potential. The expression of the apoptosis- and migration-related proteins and the phosphorylation of the nuclear factor kappa -B (NF-κB) cells were detected by Western blot. A chromatin immunoprecipitation (ChIP) analysis was conducted to examine NF-κB p65 binding to the myeloid cell leukemia-1 (Mcl-1) promoter. A xenograft model of nude mice was established to verify the anticancer effects of PA in vivo.ResultsPA inhibited the proliferation, migration, and invasion, and induced the apoptosis of the DU145 and PC-3 cells in a concentration-dependent manner, and was accompanied by mitochondrial membrane potential depolarization, the upregulation of cleaved caspase-3, cleaved poly ADP-ribose polymerase (PARP) and Bcl-2-associated X protein (Bax), and the downregulation of B-cell lymphoma-2 (Bcl-2), Ki67, and Mcl-1. In relation to the mechanism, PA significantly downregulated the phosphorylation of inhibitor of NF-κB α (IκBα) and p65 and the expression of matrix metalloprotein (MMP)-2, MMP-7, MMP-9, and vascular endothelial growth factor (VEGF). PA prevented p65 binding to the Mcl-1 promoter by inactivating NF-κB p65, downregulated the transcription of Mcl-1, and the silencing of p65 increased the sensitivity of the CRPC cells to PA-induced apoptosis. The overexpression of Mcl-1 significantly reversed the PA-induced apoptosis of the CRPC cells. Additionally, consistent with our in-vitro study, PA inhibited tumor growth in the mouse xenograft model.ConclusionsWe found that PA inhibits the growth, migration, and invasion of CRPC cells in vitro and in vivo by inducing an apoptosis mechanism and inhibiting NF-κB activity. Our findings may provide therapeutic targets for this malignant tumor.

Novel insights into the anti-cancer effects of 3-bromopyruvic acid against castration-resistant prostate cancer

3-bromopyruvic acid (3-BP), a small molecule alkylating agent, has been emerged as a glycolytic inhibitor with anticancer activities. However, the effects of 3-BP on the growth and metastasis in prostate cancer have not been well investigated. Here we investigated the anti-cancer effects of 3-BP on prostate cancer in vitro and in vivo. Cell growth, apoptosis, migration, motility, and invasion were examined. The tumor growth ability was determined using a xenograft murine model. Transcriptome analysis using RNA-seq was performed to explore the mechanism of action of 3-BP. Our experimental results showed that 3-BP effectively inhibits prostate cancer cell growth, especially in castration-resistant prostate cancer (CRPC) cells. Moreover, 3-BP induces apoptosis and suppresses cell migration, motility, epithelial-mesenchymal transition (EMT), and invasion in CRPC cells. In addition, 3-BP also attenuates tumor growth in a xenograft murine model. Through transcriptome analysis using RNA-seq, 3-BP significantly regulates the cell cycle pathway and decreases the expression of downstream cycle cycle-associated genes in CRPC cells. The results of cell cycle analysis indicated that 3-BP arrests cell cycle progression at G2/M in CRPC cells. These results suggest that 3-BP has the potential in inhibiting CRPC progression and might be a promising drug for CRPC treatment.

High-dose-androgen-induced autophagic cell death to suppress the Enzalutamide-resistant prostate cancer growth via altering the circRNA-BCL2/miRNA-198/AMBRA1 signaling

Androgen deprivation therapy (ADT) is a gold standard treatment for advanced PCa. However, most patients eventually develop the castration-resistant prostate cancer (CRPC) that progresses rapidly despite ongoing systemic androgen deprivation. While early studies indicated that high physiological doses of androgens might suppress rather than promote PCa cell growth in some selective CRPC patients, the exact mechanism of this opposite effect remains unclear. Here we found that Enzalutamide-resistant (EnzR) CRPC cells can be suppressed by the high-dose-androgen (dihydrotestosterone, DHT). Mechanism dissection suggested that a high-dose-DHT can suppress the circular RNA-BCL2 (circRNA-BCL2) expression via transcriptional regulation of its host gene BCL2. The suppressed circRNA-BCL2 can then alter the expression of miRNA-198 to modulate the AMBRA1 expression via direct binding to the 3′UTR of AMBRA1 mRNA. The consequences of high-dose-DHT suppressed circRNA-BCL2/miRNA-198/AMBRA1 signaling likely result in induction of the autophagic cell death to suppress the EnzR CRPC cell growth. Preclinical studies using in vivo xenograft mouse models also demonstrated that AMBRA1-shRNA to suppress the autophagic cell death can weaken the effect of high-dose-DHT on EnzR CRPC tumors. Together, these in vitro and in vivo data provide new insights for understanding the mechanisms underlying high-dose-DHT suppression of the EnzR CRPC cell growth, supporting a potential therapy using high-dose-androgens to suppress CRPC progression in the future.

PIP5K1α is Required for Promoting Tumor Progression in Castration-Resistant Prostate Cancer.

PIP5K1α has emerged as a promising drug target for the treatment of castration-resistant prostate cancer (CRPC), as it acts upstream of the PI3K/AKT signaling pathway to promote prostate cancer (PCa) growth, survival and invasion. However, little is known of the molecular actions of PIP5K1α in this process. Here, we show that siRNA-mediated knockdown of PIP5K1α and blockade of PIP5K1α action using its small molecule inhibitor ISA-2011B suppress growth and invasion of CRPC cells. We demonstrate that targeted deletion of the N-terminal domain of PIP5K1α in CRPC cells results in reduced growth and migratory ability of cancer cells. Further, the xenograft tumors lacking the N-terminal domain of PIP5K1α exhibited reduced tumor growth and aggressiveness in xenograft mice as compared to that of controls. The N-terminal domain of PIP5K1α is required for regulation of mRNA expression and protein stability of PIP5K1α. This suggests that the expression and oncogenic activity of PIP5K1α are in part dependent on its N-terminal domain. We further show that PIP5K1α acts as an upstream regulator of the androgen receptor (AR) and AR target genes including CDK1 and MMP9 that are key factors promoting growth, survival and invasion of PCa cells. ISA-2011B exhibited a significant inhibitory effect on AR target genes including CDK1 and MMP9 in CRPC cells with wild-type PIP5K1α and in CRPC cells lacking the N-terminal domain of PIP5K1α. These results indicate that the growth of PIP5K1α-dependent tumors is in part dependent on the integrity of the N-terminal sequence of this kinase. Our study identifies a novel functional mechanism involving PIP5K1α, confirming that PIP5K1α is an intriguing target for cancer treatment, especially for treatment of CRPC.

M6A-induced repression of SIAH1 facilitates alternative splicing of androgen receptor variant 7 by regulating CPSF1

Androgen receptor splice variant 7 (AR-v7), a constitutively active transcription factor, plays a crucial role in the progression of castration-resistant prostate cancer (CRPC). Here, we found that the cleavage and polyadenylation specificity factor 1 (CPSF1) (the largest subunit of the multi-protein cleavage and polyadenylation specificity complex), regulated by the E3 ubiquitin ligases SIAH1, promoted AR-v7 expression. The data from microarray-based analysis and clinical specimen-based analysis showed that SIAH1 expression was decreased in PCa and was negatively correlated with aggressive phenotypes of PCa. SIAH1 repressed PCa cell growth and invasion under castrate conditions. SIAH1 directly interacted with CPSF1 and promoted ubiquitination and degradation of CPSF1. CPSF1 expression was negatively correlated with SIAH1 expression, but positively with PCa progression. CPSF1 overexpression switched the AR splicing pattern and facilitated the generation of the oncogenic isoform (AR-v7) by binding to the AAUAAA polyadenylation signal contained in AR-cryptic exon CE3. Functionally, SIAH1 acted as a tumor suppressor in PCa pathogenesis by repressing CPSF1-mediated AR-v7 generation. Finally, we demonstrated that m6A methylation was concerned with the repression of SIAH1 in PCa. Our results define SIAH1/CPSF1/AR-v7 axis as a regulatory factor of PCa progression, providing a promising target for treating PCa.

Exosomal LINC01213 Plays a Role in the Transition of Androgen-Dependent Prostate Cancer Cells into Androgen-Independent Manners.

Background Castration-resistant prostate cancer (CRPC), one of the prostate cancers, is a medical conundrum around the world. Some studies have demonstrated that many long noncoding RNAs in exosomes are very important in many types of cancer, including prostate cancer. However, until now, the function of exosomes in the occurrence and development of CRPC has not been reported. Methods In vitro, cell coculture was used in LNCap cells and PC-3 cells, while the isolation and purification of exosomes and the subsequent treatment assays were used in functional studies. In vitro assays were performed to detect the transformation of ADPC cells (androgen-dependent prostate cancer) into AIPC cells (androgen-independent prostate cancer). Subsequently, a lncRNA-sequencing assay was performed to detect different lncRNA expression profiles in ADPC cells cocultured with or without AIPC exosomes. The role of LINC01213 was analysed by a TCGA database after silencing the expression of LINC01213. CCK-8, qRT-PCR, and Western blotting studies were performed to analyse the possible mechanism by which exosomes participate in prostate cancer progression. Results In the coculture system, ADPC cells acquired androgen deprivation tolerance through exosome-mediated intercellular communication. Exosomes secreted by AIPC cells can promote the transformation of ADPC cells into androgen-independent cells in vitro and in vivo. lncRNA sequencing showed that LINC01213 was upregulated in exosomes derived from AIPC cell lines. The rescue experiments were preformed, and the results revealed that most of the functions of LINC01213 were performed by Wnt/β-catenin. Conclusions All the findings showed that exosomes play a key role in CRPC progression by upregulating LINC01213 and activating Wnt/β-catenin signalling.

Prostate-Specific Antigen and Time to PSA Nadir as Prognostic Significance in Castration-Resistant Prostate Cancer

Highlight:Assessing the survival rate in castration-resistant prostate cancer was descriptived.PSA level between survivor and non survivor was significant but not for PSA nadir level, TTN and TTC.Initial PSA level can predict survival prognosis rate of castration-resistant prostate cancer patients. Abstract:High mortality rates was often found in castration-resistant prostate cancer (CRPC). Our aim on this research was to assess the PSA level and time to PSA nadir as a prognostic tool for survival in CRPC patients. Several factors are considered to be useful as prognostic marker in CRPC patients. This study was a descriptive study assessing the survival rate in castration-resistant prostate cancer. Evaluation data included sex, age, initial PSA level, final PSA level, time to PSA nadir (TTN), time to CRPC progression (TTC), and survival status. A total of 24 patients with CRPC were evaluated in this study. There was significant difference found of initial PSA level between survivor (445.7 + 165.6 ng/mL) and non-survivor (200.7 + 144.9 ng/mL). There were no significant differences were also found in PSA nadir level, TTN and TTC between survivor and non-survivor groups. This study revealed that there was association between initial PSA level on survival rate of CRPC patients. Initial PSA level could be used to predict survival prognosis in CRPC patients.

A microRNA-based classifier for identification of neuroendocrine differentiation in metastatic castration-resistant prostate cancer.

149 Background: Therapy-induced neuroendocrine prostate cancer (NEPC) is an extremely aggressive variant of castration-resistant prostate cancer (CRPC) that is increasing in incidence with the widespread use of second generation of androgen receptor (AR)-pathway inhibitors (APIs) such as enzalutamide (ENZ) and abiraterone. This aggressive variant arises from CRPC-Adenocarcinomas (CRPC-Adeno) via a reversible trans-differentiation process, referred to as neuroendocrine differentiation (NED) wherein cells undergo a lineage switch and exhibit neuroendocrine (NE) features, characterized by expression of neuronal markers such as enolase 2 (ENO2), chromogranin A (CHGA) and synaptophysin (SYP). Currently, histopathological assessment combined with immunohistochemical detection in PCa tissues/serum levels of neuronal markers including SYP, NSE, CHGA and CD56 is currently used to monitor NED in CRPC patients. However, these markers are not sufficiently specific, highlighting the urgent need of novel molecular markers to assess emergence of NED in CRPC patients. Recently, we demonstrated that progression of advanced CRPC with adenocarcinoma characteristics to CRPC-NE is associated with a characteristic set of miRNA alterations that promote plasticity of advanced PCa to NEPC (Bhagirath et al., Oncogene, 2020). Importantly, we could develop a ‘novel miRNA classifier’ to robustly stratify CRPC-NE tumors from CRPC-Adenocarcinomas. Here we further validate the classifier in independent clinical cohorts and deduce the optimal miRNA genes required for NEPC diagnosis. Methods: Human clinical samples with corresponding clinical information were procured from two independent sites of Prostate Cancer Biorepository Network (PCBN). FFPE sections from clinical samples were microdissected, RNA were extracted and small RNA sequencing was performed using an Illumina NextSeq 500 platform. Sequencing data were analyzed and machine learning algorithms were applied. The performance of classifier was measured using receiver operating characteristic (ROC) analysis with area under the curve (AUC) as the primary evaluation metric. Results: Unsupervised analysis of sequencing data by principal component analyses (PCA) revealed distinct clustering of the CRPC-NE tumors from CRPC-Adenocarcinomas based on miRNA profiles suggesting that miRNA profiles can be used to stratify these tumor types. We applied the ‘43-miRNA classifier data’ we deduced earlier to these validation cohorts. Our analyses showed that a set of 5 miRNAs of the classifier are important in distinguishing between CRPC-Adeno vs CRPC-NE with an AUC=0.8318. Conclusions: A ‘5- miRNA’ classifier was validated to be of significance in two independent validation cohorts. We propose this miRNA classifier as an important tool for diagnosing NED in CRPC patients.

The central role of Sphingosine kinase 1 in the development of neuroendocrine prostate cancer (NEPC): A new targeted therapy of NEPC.

BackgroundNeuroendocrine prostate cancer (NEPC) is often diagnosed as a sub‐type from the castration‐resistant prostate cancer (CRPC) recurred from the second generation of anti‐androgen treatment and is a rapidly progressive fatal disease. The molecular mechanisms underlying the trans‐differentiation from CRPC to NEPC are not fully characterized, which hampers the development of effective targeted therapy.MethodsBioinformatic analyses were conducted to determine the clinical correlation of sphingosine kinase 1 (SphK1) in CRPC progression. To investigate the transcriptional regulation SphK1 and neuroendocrine (NE) transcription factor genes, both chromosome immunoprecipitation and luciferase reporter gene assays were performed. To demonstrate the role of SphK1 in NEPC development, neurosphere assay was carried out along with several biomarkers determined by quantitative PCR and western blot. Furthermore, in vivo NEPC xenograft models and patient‐derived xenograft (PDX) model were employed to determine the effect of SphK1 inhibitors and target validation.ResultsSignificant prevalence of SphK1 in NEPC development is observed from clinical datasets. SphK1 is transcriptionally repressed by androgen receptor‐RE1‐silencing transcription factor (REST) complex. Furthermore, sphingosine 1‐phosphate produced by SphK1 can modulate REST protein turnover via MAPK signaling pathway. Also, decreased REST protein levels enhance the expression of NE markers in CRPC, enabling the transition to NEPC. Finally, specific SphK1 inhibitors can effectively inhibit the growth of NEPC tumors and block the REST protein degradation in PDX.ConclusionsSphK1 plays a central role in NEPC development, which offers a new target for this lethal cancer using clinically approved SphK1 inhibitors.

The HeyL-Aromatase Axis Promotes Cancer Stem Cell Properties by Endogenous Estrogen-Induced Autophagy in Castration-Resistant Prostate Cancer.

Treatment of patients with castration-resistant prostate cancer (CRPC) remains a major clinical challenge. We previously showed that estrogenic effects contribute to CRPC progression and are primarily caused by the increased endogenous estradiol produced via highly expressed aromatase. However, the mechanism of aromatase upregulation and its role in CRPC are poorly described. In this study, we report that HeyL is aberrantly upregulated in CRPC tissues, and its expression is positively correlated with aromatase levels. HeyL overexpression increased endogenous estradiol levels and estrogen receptor-α (ERα) transcriptional activity by upregulating CYP19A1 expression, which encodes aromatase, enhancing prostate cancer stem cell (PCSC) properties in PC3 cells. Mechanistically, HeyL bound to the CYP19A1 promoter and activated its transcription. HeyL overexpression significantly promoted bicalutamide resistance in LNCaP cells, which was reversed by the aromatase inhibitor letrozole. In PC3 cells, the HeyL-aromatase axis promoted the PCSC phenotype by upregulating autophagy-related genes, while the autophagy inhibitor chloroquine (CQ) suppressed the aromatase-induced PCSC phenotype. The activated HeyL-aromatase axis promoted PCSC autophagy via ERα-mediated estrogenic effects. Taken together, our results indicated that the HeyL-aromatase axis could increase endogenous estradiol levels and activate ERα to suppress PCSC apoptosis by promoting autophagy, which enhances the understanding of how endogenous estrogenic effects influence CRPC development.

Alterations of Plasma Exosomal Proteins and Metabolites are Associated with the Progression of Castration-Resistant Prostate Cancer

Alterations of Plasma Exosomal Proteins and Metabolites are Associated with the Progression of Castration-Resistant Prostate Cancer

AR Structural Variants and Prostate Cancer.

Therapeutic interventions for advanced castration-resistant prostate cancer (CRPC) are focused on inhibiting the androgen receptor (AR) through targeting of its C-terminal ligand binding domain (LBD). However, a significant subset of CRPC patients demonstrate primary resistance to androgen deprivation and anti-androgen therapies, suggesting that other targets, outside of the AR, might be pertinent to the cancer progression. One explanation is the expression of androgen receptor splice variants (AR-Vs). So far, more than 20 AR-Vs have been identified from both prostate cancer cell lines and prostate cancer tissue biopsies. Most of the AR-Vs have a conserved N-terminal domain, but lack the LBD, yet retain the ability to bind DNA and activate downstream signaling. Although it remains unclear whether AR-Vs are principal divers or mere bystanders of CRPC progression, inhibiting AR-Vs, through drugs that target the AR transactivation function outside of the LBD, has been a major emphasis for next generation therapeutics in prostate cancer. This book chapter is dedicated to the role of AR variants and their clinical importance. We will review the initial discovery of AR-Vs, their regulation and prevalence, as well as their biological function in prostate cancer. We will provide an overview of the role of AR-Vs in the development of metastatic CRPC and in promoting clinical treatment failures. Lastly, we will present an introduction to the therapeutic approaches towards developing AR-V-targeted therapies including the continuing progress, the old challenges, and the new prospects.

Rapid Androgen-Responsive Proteome Is Involved in Prostate Cancer Progression.

Androgen exerts its functions by binding with an androgen receptor (AR). It can activate many signaling pathways that are important to the progression of castration-resistant prostate cancer (CRPC). Here, we characterized the rapid proteomic changes seen at 5, 15, 30, and 60 min after the androgen treatment of VCaP cells via the tandem mass tag (TMT) labeling strategy. A total of 5529 proteins were successfully identified and quantified. Dynamic time profiling of protein expression patterns allowed us to identify five protein clusters involved in various stages of androgen-initiated signal transmission and processing. More details of protein functions and localization patterns, and our elucidation of an AR-interacting protein network, were obtained. Finally, we validated the expression level of AR-regulated proteins known to be significantly regulated in CRPC patients using the mouse xenograft model and patient samples. Our work offers a systematic analysis of the rapid proteomic changes induced by androgen and provides a global view of the molecular mechanisms underlying CRPC progression.

Abstract P202: Initial findings from an ongoing first-in-human phase 1 study of the CBP/p300 inhibitor FT-7051 in men with metastatic castration-resistant prostate cancer

Abstract Background: Prostate cancer is the 2nd leading cause of cancer-related deaths among men in the US. CREB binding protein (CBP) and paralog p300 are co-activators of androgen receptor (AR) relevant to metastatic castration-resistant prostate cancer (mCRPC) progression and AR therapy resistance. FT-7051 is an oral, potent and selective inhibitor of CBP/p300 bromodomain with activity in preclinical prostate cancer models, including those resistant to enzalutamide. Methods: The Courage Study (NCT04575766) is a first-in-human, multicenter, phase 1, open-label study to examine the safety, PK/PD, and preliminary anti-tumor activity of FT-7051 in mCRPC patients (pts) who have progressed despite prior therapy, including at least one AR pathway inhibitor. The study uses a Bayesian optimal interval (BOIN) design with an accelerated titration phase. FT-7051 is dosed on a 28-d cycle (21-d on/7-d off). Following accelerated titration, dose escalation/de-escalation decisions are made by comparing the observed dose-limiting toxicity (DLT) rate at the current dose with pre-specified dose escalation/de-escalation boundaries. The primary objectives are to evaluate safety and tolerability of FT-7051 and determine the recommended phase 2 dose. Key secondary endpoints include PSA at 12 wks, time to PSA progression, time to radiographic progression, overall response rate, and PK parameters. Biomarker analyses include PD assessments of CBP/p300 inhibition in surrogate tissues and genetic analyses in circulating tumor cells (AR, AR-v7) and peripheral blood. Results: As of 18-June-2021, a total of 5 pts were enrolled with exposure data entered into the database, with 2 pts ongoing and 3 pts discontinued (disease progression, n=1; no longer clinically benefitting, n=1; subject withdrawal, n=1). Pts had a median age of 71 yrs (range: 66-82) with a median time since first mCRPC diagnosis of 2.3 yrs (0.4-4.7) and a median of 3 (1-5) prior lines of mCRPC therapy. Mutations reported by the investigator for 3 pts included MYC, p53, RB1, AR, and PTEN loss. Preliminary PK analyses indicated that FT-7051 exposure increased with dose in a greater than dose-proportional manner. Importantly, observed FT-7051 exposures were consistent with the predicted efficacious exposure threshold derived from PK/efficacy modeling in preclinical studies. TEAEs were reported in 4 (80%) pts. Most TEAEs were mild (Gr1) or moderate (Gr2), ≥Gr3 TEAEs included one event of possibly related Gr3 hyperglycemia and one event of unrelated Gr5 disease progression. Conclusions: Preliminary safety and PK data from the accelerated titration phase of this BOIN study support the continued investigation of FT-7051 in men with mCRPC. Initial PK data confirm that FT-7051 exposure is consistent with the predicted efficacious exposure threshold determined by PK/efficacy modeling. Additional analyses of PSA, PD assessments, and genetic analyses, including AR-v7 status, will be reported. Citation Format: Andrew J. Armstrong, Michael S. Gordon, Melissa A. Reimers, Arif Hussain, Vaibhav G. Patel, Elaine T. Lam, Alex Sedkov, Von Potter, Neal Shore. Initial findings from an ongoing first-in-human phase 1 study of the CBP/p300 inhibitor FT-7051 in men with metastatic castration-resistant prostate cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P202.

RETRACTED ARTICLE: Targeting KDM4A-AS1 represses AR/AR-Vs deubiquitination and enhances enzalutamide response in CRPC

Castration-resistant prostate cancer (CRPC) is a highly malignant type of advanced cancer resistant to androgen deprivation therapy. One of the important mechanisms for the development of CRPC is the persistent imbalanced regulation of AR and AR splice variants (AR/AR-Vs). In this study, we reported KDM4A-AS1, a recently discovered lncRNA, as a tumor promoter that was significantly increased in CRPC cell lines and cancer tissues. Depletion of KDM4A-AS1 significantly reduced cell viability, proliferation, migration in vitro, and tumor growth in vivo. We found that by binding to the NTD domain, KDM4A-AS1 enhances the stability of USP14-AR/AR-Vs complex, and promoted AR/AR-Vs deubiquitination to protect it from MDM2-mediated ubiquitin-proteasome degradation. Moreover, KDM4A-AS1 was found to enhance CRPC drug resistance to enzalutamide by repressing AR/AR-Vs degradation; antisense oligonucleotide drugs targeting KDM4A-AS1 significantly reduced the growth of tumors with enzalutamide resistance. Taken together, our results indicated that KDM4A-AS1 played an important role in the progression of CRPC and enzalutamide resistance by regulating AR/AR-Vs deubiquitination; targeting KDM4A-AS1 has broad clinical application potential.

KIF15 Promotes Progression of Castration Resistant Prostate Cancer by Activating EGFR Signaling Pathway.

Castration-resistant prostate cancer (CRPC) continues to be a major clinical problem and its underlying mechanisms are still not fully understood. The epidermal growth factor receptor (EGFR) activation is an important event that regulates mitogenic signaling. EGFR signaling plays an important role in the transition from androgen dependence to castration-resistant state in prostate cancer (PCa). Kinesin family member 15 (KIF15) has been suggested to be overexpressed in multiple malignancies. Here, we demonstrate that KIF15 expression is elevated in CRPC. We show that KIF15 contributes to CRPC progression by enhancing the EGFR signaling pathway, which includes complex network intermediates such as mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/AKT pathways. In CRPC tumors, increased expression of KIF15 is positively correlated with EGFR protein level. KIF15 binds to EGFR, and prevents EGFR proteins from degradation in a Cdc42-dependent manner. These findings highlight the key role of KIF15 in the development of CRPC and rationalize KIF15 as a potential therapeutic target.

Enzalutamide-Resistant Progression of Castration-Resistant Prostate Cancer Is Driven via the JAK2/STAT1-Dependent Pathway.

Previous studies showed that CXCR7 expression was upregulated after enzalutamide (ENZ) treatment, and an increased level of CXCR7 could increase the invasion, migration, and angiogenesis of castration-resistant prostate cancer (CRPC) cells. This study demonstrated that the levels of p-JAK2, p-STAT1, C-Myc, and VEGFR2 were significantly reduced after CCX771, a specific CXCR7 inhibitor, treatment. This effect further increased after the combination treatment of ENZ and CCX771. Then, we verified that targeting the inhibition of JAK2 or STAT1 could remarkably increase apoptosis and DNA damage and decrease the migration of CRPC cells. More importantly, the combination treatment of ENZ + JAK2/STAT1 led to much greater suppression than the single-agent treatment of JAK2 or STAT1. Subcutaneous CRPC xenograft tumor growth was also reduced by single-agent ENZ treatment and single-agent FLUD, a specific STAT1 antagonist, treatment; but much superior effect was elicited by the combination treatment of ENZ + FLUD. The proliferative indices significantly decreased following combination treatment in tumor tissues compared with control-treatment tissues and single-agent-treatment tissues. Our results demonstrated that CXCR7, which signifies an androgen receptor (AR)-independent signaling pathway, caused CRPC progression via the downstream JAK2/STAT1 signal transduction cascade. Combined inhibition targeting both the AR and JAK2/STAT1 resulted in substantial tumor suppression due to the reduction in DNA damage repair ability and increment in apoptosis.