Pathways In Castration-resistant Prostate Cancer Research Articles

Identification of castration-dependent and -independent driver genes and pathways in castration-resistant prostate cancer (CRPC)

BackgroundProstate cancer (PCa) is one of the most diagnosed cancers in the world. PCa inevitably progresses to castration-resistant prostate cancer (CRPC) after androgen deprivation therapy treatment, and castration-resistant state means a shorter survival time than other causes. Here we aimed to define castration-dependent and -independent diver genes and molecular pathways in CRPC which are responsible for such lethal metastatic events.MethodsBy employing digital gene expression (DGE) profiling, the alterations of the epididymal gene expression profile in the mature and bilateral castrated rat were explored. Then we detect and characterize the castration-dependent and -independent genes and pathways with two data set of CPRC-associated gene expression profiles publicly available on the NCBI.ResultsWe identified 1,632 up-regulated and 816 down-regulated genes in rat’s epididymis after bilateral castration. Differential expression analysis of CRPC samples compared with the primary PCa samples was also done. In contrast to castration, we identified 97 up-regulated genes and 128 down-regulated genes that changed in both GEO dataset and DGE profile, and 120 up-regulated genes and 136 down-regulated genes changed only in CRPC, considered as CRPC-specific genes independent of castration. CRPC-specific DEGs were mainly enriched in cell proliferation, while CRPC-castration genes were associated with prostate gland development. NUSAP1 and NCAPG were identified as key genes, which might be promising biomarkers of the diagnosis and prognosis of CRPC.ConclusionOur study will provide insights into gene regulation of CRPC dependent or independent of castration and will improve understandings of CRPC development and progression.

Targeting the MYCN-PARP-DNA Damage Response Pathway in Neuroendocrine Prostate Cancer.

Purpose: We investigated MYCN-regulated molecular pathways in castration-resistant prostate cancer (CRPC) classified by morphologic criteria as adenocarcinoma or neuroendocrine to extend the molecular phenotype, establish driver pathways, and identify novel approaches to combination therapy for neuroendocrine prostate cancer (NEPC).Experimental Design and Results: Using comparative bioinformatics analyses of CRPC-Adeno and CRPC-Neuro RNA sequence data from public data sets and a panel of 28 PDX models, we identified a MYCN-PARP-DNA damage response (DDR) pathway that is enriched in CRPC with neuroendocrine differentiation (NED) and CRPC-Neuro. ChIP-PCR assay revealed that N-MYC transcriptionally activates PARP1, PARP2, BRCA1, RMI2, and TOPBP1 through binding to the promoters of these genes. MYCN or PARP1 gene knockdown significantly reduced the expression of MYCN-PARP-DDR pathway genes and NED markers, and inhibition with MYCNsi and/or PARPsi, BRCA1si, or RMI2si significantly suppressed malignant activities, including cell viability, colony formation, and cell migration, in C4-2b4 and NCI-H660 cells. Targeting this pathway with AURKA inhibitor PHA739358 and PARP inhibitor olaparib generated therapeutic effects similar to those of gene knockdown in vitro and significantly suppressed tumor growth in both C4-2b4 and MDACC PDX144-13C subcutaneous models in vivoConclusions: Our results identify a novel MYCN-PARP-DDR pathway that is driven by N-MYC in a subset of CRPC-Adeno and in NEPC. Targeting this pathway using in vitro and in vivo CRPC-Adeno and CRPC-Neuro models demonstrated a novel therapeutic strategy for NEPC. Further investigation of N-MYC-regulated DDR gene targets and the biological and clinical significance of MYCN-PARP-DDR signaling will more fully elucidate the importance of the MYCN-PARP-DDR signaling pathway in the development and maintenance of NEPC. Clin Cancer Res; 24(3); 696-707. ©2017 AACR.

Abstract 2406: LSD1 promotes castration-resistant prostate cancer cell survival independently of the androgen receptor and of histone demethylation

Abstract Background: Androgen deprivation therapy (ADT) or interference with androgen receptor (AR) function is the principal treatment for advanced prostate cancer. However, progression is universal, and therapies following the emergence of castration resistance do not offer durable control of the disease. Lysine specific demethylase 1 (LSD1) is a histone demethylase and a key regulator of gene expression in cancer. Prior work demonstrates that LSD1 may act as a cofactor of the AR in androgen-dependent prostate cancer cells. In this report, we describe a distinct role of LSD1 as a driver of proliferation and survival of castration-resistant prostate cancer (CRPC) cells independently of the AR and independently of histone demethylation. Methods: We used gain and loss of function studies to determine the importance of LSD1 for survival of prostate cancer cells. To identify transcriptional networks that contribute to cell survival, we suppressed LSD1 with RNAi and measured gene expression changes with microarrays. To determine the importance of histone demethylation in regulation of these gene networks, we suppressed LSD1 and measured levels of LSD1 canonical histone substrates (H3K4me2 and H3K9me2) genome-wide with chromatin immunoprecipitation-sequencing. Results: Cell viability assays demonstrated that LSD1 is important for proliferation and survival of CRPC cells independently of the AR. Microarray studies demonstrated that LSD1 activates androgen-independent genes that comprise cell cycle and embryonic stem cell maintenance gene sets that are enriched in lethal human tumors. Importantly, our global epigenomic studies after LSD1 suppression demonstrated that LSD1 activates these gene sets independently of demethylation of its canonical histone substrates. Conclusions: Our results demonstrate that LSD1 promotes CRPC cell survival independently of the AR and suggest that LSD1 regulates key pathways in CRPC through demethylation of non-histone substrates or via a scaffold function―mechanisms we are currently investigating. In summary, LSD1 contributes to CRPC cell survival through non-canonical mechanisms and represents an attractive therapeutic target in lethal prostate cancer. Citation Format: Archana Sehrawat, Lina Gao, Junior Tayou, Armand Bankhead, Laura M. Heiser, Carly J. King, Yuliang Wang, Jacob Schwartzman, Joshua Urrutia, Daniel J. Coleman, Sheila Weinmann, Bhaskar V. Kallakury, Deborah L. Berry, Reina Haque, Stephen K. Van Den Eeden, Tomasz M. Beer, George V. Thomas, Shannon McWeeney, Joshi J. Alumkal. LSD1 promotes castration-resistant prostate cancer cell survival independently of the androgen receptor and of histone demethylation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2406. doi:10.1158/1538-7445.AM2017-2406

Abstract 5039: Co-targeting polo-like kinase 1(Plk1) and the Wnt/β-catenin signaling pathway in castration-resistant prostate cancer

Abstract The Wnt/β-catenin signaling pathway has been identified as one of the predominantly upregulated pathways in castration-resistant prostate cancer (CRPC). However, whether targeting the β-catenin pathway will prove effective as a CRPC treatment remains unknown. Polo-like kinase 1 (Plk1) is a critical regulator in many cell cycle events and is significantly elevated upon castration of mice carrying xenograft prostate tumors. Indeed, inhibition of Plk1 has been shown to inhibit tumor growth in several in vivo studies. Here, we show that Plk1 is a negative regulator of Wnt/β-catenin signaling. Plk1 inhibition or depletion enhances the level of cytosolic and nuclear β-catenin in human prostate cancer cells. Furthermore, inhibition of Wnt/β-catenin signaling significantly potentiates the anti-neoplastic activity of the Plk1 inhibitor BI2536 in both cultured prostate cancer cells and CRPC xenograft tumors. Mechanistically, Axin2, a negative regulator of the β-catenin pathway, serves as a substrate of Plk1 and Plk1 phosphorylation of Axin2 facilitates the degradation of β-catenin by enhancing the binding between GSK3β and β-catenin. Plk1 phosphorylated Axin2 also exhibits resistance to Cdc20-mediated degradation. Overall, this study identifies a novel Plk1-Wnt signaling axis in prostate cancer, offering a promising new therapeutic option to treat CRPC. Citation Format: Jie Li, Xiaoqi Liu. Co-targeting polo-like kinase 1(Plk1) and the Wnt/β-catenin signaling pathway in castration-resistant prostate cancer. [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 5039.

Combination of carmustine and selenite effectively inhibits tumor growth by targeting androgen receptor, androgen receptor‐variants, and Akt in preclinical models: New hope for patients with castration resistant prostate cancer

Despite established androgen receptor (AR) antagonists, AR/AR-variants signaling remain a major obstacle for the successful treatment of castration resistant prostate cancer (CRPC). In addition, CRPC cells adapt to survive via AR-independent pathways to escape next generation therapies. Therefore, there is an urgent need for drugs that can target these signaling pathways in CRPC. In this study, we sought to determine whether carmustine and selenite in combination could induce apoptosis and inhibit growth of CRPC in-vitro and in-vivo. CRPC (22Rv1, VCaP, and PC-3) cell lines in culture and xenograft mouse were used. Combination of carmustine and selenite treatment significantly increased reactive oxygen species, apoptosis and growth inhibition in CRPC cells with down regulation of anti-apoptotic (Bcl-2 and Mcl-1) and proliferative proteins (c-Myc and cyclin-D1). This effect was associated with complete reduction of AR/AR-variants, AR-V7, PSA and significant induction of p27Kip1. Combination treatment substantially abolished phospho-Akt, phospho-GSK-3β, and anchorage-independent growth in AR-positive and AR-negative cells. Consistent with in-vitro results, combination treatment effectively induced apoptosis and completely inhibited xenograft tumor growth and markedly reduced AR/AR-variants, AR-V7, PSA, and Bcl-2 in xenograft tumors without causing genotoxicity in host mice. Individual agent treatment showed only partial effect. The combination treatment showed a significant synergistic effect. The present study is the first to demonstrate that the combination of carmustine and selenite treatment completely suppressed CRPC tumor growth by reducing AR/AR-variants and Akt signaling. Our findings suggest that the combination of carmustine and selenite could constitute a promising next-generation therapy for successful treatment of patients with CRPC.

Cotargeting Polo-Like Kinase 1 and the Wnt/β-Catenin Signaling Pathway in Castration-Resistant Prostate Cancer.

The Wnt/β-catenin signaling pathway has been identified as one of the predominantly upregulated pathways in castration-resistant prostate cancer (CRPC). However, whether targeting the β-catenin pathway will prove effective as a CRPC treatment remains unknown. Polo-like kinase 1 (Plk1) is a critical regulator in many cell cycle events, and its level is significantly elevated upon castration of mice carrying xenograft prostate tumors. Indeed, inhibition of Plk1 has been shown to inhibit tumor growth in several in vivo studies. Here, we show that Plk1 is a negative regulator of Wnt/β-catenin signaling. Plk1 inhibition or depletion enhances the level of cytosolic and nuclear β-catenin in human prostate cancer cells. Furthermore, inhibition of Wnt/β-catenin signaling significantly potentiates the antineoplastic activity of the Plk1 inhibitor BI2536 in both cultured prostate cancer cells and CRPC xenograft tumors. Mechanistically, axin2, a negative regulator of the β-catenin pathway, serves as a substrate of Plk1, and Plk1 phosphorylation of axin2 facilitates the degradation of β-catenin by enhancing binding between glycogen synthase kinase 3β (GSK3β) and β-catenin. Plk1-phosphorylated axin2 also exhibits resistance to Cdc20-mediated degradation. Overall, this study identifies a novel Plk1-Wnt signaling axis in prostate cancer, offering a promising new therapeutic option to treat CRPC.

Divergent Androgen Receptor and Beta-Catenin Signaling in Prostate Cancer Cells.

Despite decades of effort to develop effective therapy and to identify promising new drugs, prostate cancer is lethal once it progresses to castration-resistant disease. Studies show mis-regulation of multiple pathways in castration-resistant prostate cancer (CRPC), reflecting the heterogeneity of the tumors and also hinting that targeting androgen receptor (AR) pathway alone might not be sufficient to treat CRPC. In this study, we present evidence that the Wnt/β-catenin pathway might be activated in prostate cancer cells after androgen-deprivation to promote androgen-independent growth, partly through enhanced interaction of β-catenin with TCF4. Androgen-independent prostate cancer cells were more prone to activate a Wnt-reporter, and inhibition of the Wnt/β-catenin pathway increased sensitivity of these cells to the second-generation antiandrogen, enzalutamide. Combined treatment of enzalutamide and Wnt/β-catenin inhibitor showed increased growth repression in both androgen-dependent and -independent prostate cancer cells, suggesting therapeutic potential for this approach.

MP49-15 DOES TUMOR MICROENVIRONMENT AFFECT THE RESPONSE OF CASTRATION RESISTANT PROSTATE CANCER TO THERAPY IN BONE VS VISCERAL METASTASES?

You have accessJournal of UrologyProstate Cancer: Basic Research IV1 Apr 2014MP49-15 DOES TUMOR MICROENVIRONMENT AFFECT THE RESPONSE OF CASTRATION RESISTANT PROSTATE CANCER TO THERAPY IN BONE VS VISCERAL METASTASES? Maahum Haider, Ilsa Coleman, Xiaotun Zhang, Lisha Brown, Lori Kollath, Shahriar Koochekpour, Robert Montgomery, Paul Lange, Martine Roudier, Lawrence True, Celestia Higano, Peter Nelson, Robert Vessella, and Colm Morrissey Maahum HaiderMaahum Haider More articles by this author , Ilsa ColemanIlsa Coleman More articles by this author , Xiaotun ZhangXiaotun Zhang More articles by this author , Lisha BrownLisha Brown More articles by this author , Lori KollathLori Kollath More articles by this author , Shahriar KoochekpourShahriar Koochekpour More articles by this author , Robert MontgomeryRobert Montgomery More articles by this author , Paul LangePaul Lange More articles by this author , Martine RoudierMartine Roudier More articles by this author , Lawrence TrueLawrence True More articles by this author , Celestia HiganoCelestia Higano More articles by this author , Peter NelsonPeter Nelson More articles by this author , Robert VessellaRobert Vessella More articles by this author , and Colm MorrisseyColm Morrissey More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.1116AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail Introduction and Objectives Castration resistant prostate cancer (CRPC) often metastasizes to bone with evidence to suggest a differential response to treatment in bone versus visceral metastases. We identify molecular targets and pathways and their respective roles in bone metastatic CRPC. Methods We obtained tissue samples from 44 CRPC patients via rapid autopsy at the University of Washington. Each patient's clinical history, metastatic sites, pathology, and biomarker expression was evaluated. Laser capture microdissection was used to isolate mRNA from liver (n=19), lymph node (n=68) and bone metastases (n=20) and expression analyses were performed. Differential expression of proteins was validated with tissue microarrays (TMA) in bone (n=117) and visceral (n=65) metastases. Serial serum samples were assayed for prosaposin (PSAP) in patients who presented with localized disease and developed bone metastases. Results Specific genes were examined in 3 specific pathways that were altered in bone vs visceral metastases: 1) Epithelial mesenchymal transition; TWIST-associated proteins (ZEB1/2, SNAI1/2, TGFB1, VIM q<0.05), 2) Survival pathways (BAD, BAX q<0.05), and 3) Osteomimetic pathways (POSTN, SPP1, RUNX2, DKK1, DMP1, IBSP, THBS3 q<0.05). The TMAs showed that both nuclear and cytoplasmic Twist are significantly higher in bone than soft tissue metastases (p<0.01). It is mainly cytoplasmic in bone metastases, with nuclear expression seen in 24/117 bone sites and in only 1/65 soft tissue sites. This suggests that TWIST may only be transcriptionally active in a subset of epithelial cells. Gene set enrichment analysis identified mitochondrial proteins that are involved in survival pathways as being differentially expressed between bone and visceral metastases. We show overexpression of other survival proteins in addition to the previously shown BCL-2 and MCL-1. We continue to validate the expression of novel osteomimetic proteins in CRPC bone metastases and assess PSAP levels (a protein associated with disease progression and highly expressed in bone metastases). Conclusions The heterogeneity of CRPC within and between patients is a considerable obstacle in determining the appropriate treatment regimen for each patient. Our data show that differential response to therapy could be based on the site of metastases. We are also interrogating a marker that may predict future development of bone metastases and identifying molecular pathways in CRPC that could be specifically targeted in patients with predominantly bone metastatic disease. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e507-e508 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Maahum Haider More articles by this author Ilsa Coleman More articles by this author Xiaotun Zhang More articles by this author Lisha Brown More articles by this author Lori Kollath More articles by this author Shahriar Koochekpour More articles by this author Robert Montgomery More articles by this author Paul Lange More articles by this author Martine Roudier More articles by this author Lawrence True More articles by this author Celestia Higano More articles by this author Peter Nelson More articles by this author Robert Vessella More articles by this author Colm Morrissey More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Targeting MET and vascular endothelial growth factor receptor signaling in castration-resistant prostate cancer.

Effective management of bone metastases in men with castration-resistant prostate cancer (CRPC) remains an important unmet medical need. MET and vascular endothelial growth factor receptor (VEGFR) are rational targets for intervention in CRPC. Clinical trials involving agents that inhibit one but not both pathways have reported modest activity and no improvement in overall survival. Cabozantinib is an oral multitargeted tyrosine kinase inhibitor that inhibits both MET and VEGFR-2. A phase II randomized discontinuation study involving subjects with CRPC demonstrated that cabozantinib therapy is associated with improvement in bone scans, bone turnover markers, and pain response, but with significant adverse events leading to dose reduction and treatment discontinuation. Lower doses of cabozantinib retain high levels of activity with less toxicity. Ongoing phase III clinical trials will define the role of cabozantinib in CRPC. We summarize the rationale for targeting MET and VEGFR pathways in CRPC and the clinical data available to date.

A phase Ib/II study testing the safety and efficacy of combined inhibition of the AKT/PI3K and AR signaling pathways in castration-resistant prostate cancer: GDC-0068 or GDC-0980 with abiraterone acetate versus abiraterone acetate.

TPS2616 Background: Loss of PTEN, leading to activation of the AKT/PI3K pathway is frequent and associated with poor prognosis in prostate cancer. In addition, AR and AKT/PI3K cross-regulate by reciprocal feedback and combined inhibition of both pathways resulted in improved preclinical efficacy. This study is designed to evaluate the effect of combined inhibition of AR pathway (with abiraterone) and AKT/PI3K pathway (with either GDC-0068 or GDC-0980). GDC-0068 is a potent, selective ATP-competitive inhibitor of AKT1, 2, and 3. Preclinical studies showed that cell and tumor models with PTEN loss are more likely to be sensitive to GDC-0068. GDC-0068 was generally well tolerated in phase I and a MTD of 600 mg daily was identified. GDC-0980 is a potent pan-inhibitor of Class I PI3K and inhibits wild-type and mutated p110α isoforms, as well as mTOR kinase. The recommended phase II dose (RP2D) for single-agent GDC-0980 is 40 mg daily. Methods: This study will enroll CRPC patients previously treated with docetaxel. In phase Ib, the RP2D will be determined separately for GDC-0068 and GDC-0980 in combination with abiraterone 1000 mg qd and prednisone 5mg bid. In phase II, patients will be randomized 1:1:1 to receive GDC-0068 + abiraterone, GDC-0980 + abiraterone, or placebo + abiraterone. The primary endpoint of phase II is PFS measured by PCWG2 in all patients and in patients with PTEN loss. Secondary endpoints include OS, PSA response rate, ORR, safety, Pharmacokinetics and biomarker analyses. The effect of each treatment on the number of circulating tumor cells will be assessed. Primary and secondary analyses will include all randomized patients and will be conducted according to assigned treatment arm. Kaplan-Meier methodology will be used to estimate median PFS for each arm. Up to 24 patients are planned to be enrolled in phase Ib; 240 patients (80 per arm) are planned for phase II. This study is open for accrual; to date 2 patients have been enrolled in phase Ib.

Treatment of Castration-Resistant Prostate Cancer: Updates on Therapeutics Targeting the Androgen Receptor Signaling Pathway

Androgens play a critical role in the progression of castration-resistant prostate cancer through androgen receptor (AR)-regulated signaling pathways. Progress has been made in the development of potent agents designed to suppress androgen function by blocking the AR, inhibiting the synthesis of androgens, or targeting downstream AR signaling pathways. This review summarizes the development of novel therapies based on current insights into AR signaling pathways in castration-resistant prostate cancer.

&lt;b&gt;Crosstalk between the epidermal growth factor receptor and androgen receptor signaling pathways in prostate cancer&lt;/b&gt;

Malignant cells are characterized by complex and often overlapping signaling pathways that modulate uncontrolled proliferation, leading to tumor growth and cancer progression. Prostate cancer is characterized by a dependence on androgens for growth initiation, and androgen deprivation is the standard treatment for advanced disease. Invariably, progression to castration-resistant prostate cancer (CRPC) occurs. Effective treatment options are currently limited to cytotoxic chemotherapy. In addition to androgen-mediated androgen receptor (AR) signaling in CRPC, multiple growth factor pathways are active, including the epidermal growth factor (EGF) receptor family of tyrosine kinases. Crosstalk between these two pathways has been studied in prostate cancer cell lines, xenograft tumor models, and in prostate cancer patients. This manuscript will focus on EGFR signaling, AR signaling, EGFR-AR crosstalk, and therapies targeted at these receptor-mediated regulatory pathways in CRPC