The ADAM9/UBN2/AKR1C3 axis promotes resistance to androgen-deprivation in prostate cancer

Metastatic and castration-resistant disease is a fatal manifestation of prostate cancer (PCa). The mechanism through which resistance to androgen deprivation in PCa is developed remains largely unknown. Our understanding of the tumor microenvironment (TME) and key signaling pathways between tumors and their TME is currently changing in light of the generation of new knowledge with regard to cancer progression. A disintegrin and metalloproteinase domain-containing protein 9 (ADAM9) is a membranous bridge forming cell-cell and cell-matrix connections that regulate tumor aggressiveness and metastasis. However, it is not known whether ADAM9 expressed in the TME contributes to the CRPC phenotype. In this study, we aimed to investigate the expression patterns of ADAM9 in prostate cancer-associated fibroblasts (CAFs). We also intended to elucidate the effects of both stromal cell- and cancer cell-derived ADAM9 on the progression of CRPC and the implicated molecular pathways. By using both clinical specimens and cell lines, we herein showed that unlike the membrane anchored ADAM9 overexpressed by both PCa cells and prostate CAFs, the secreted isoform of ADAM9 (sADAM9) was strongly detected in CAFs, but rarely in tumor cells, and that could be a serum marker for PCa patients. We demonstrated that functionally sADAM9 are characterized as chemoattractant for the directed movement of androgen-independent PCa cells through integrin downstream FAK/AKT pathway, supporting that elevated sADAM9 by prostate CAFs could be responsible for the promotion of CRPC metastasis. Moreover, by stimulating PCa cells with sADAM9, we found that ubinuclein-2 (UBN2) expression was increased. A positive correlation of ADAM9 and UBN2 expression was observed in androgen receptor-expressing PCa cell lines and further confirmed in clinical PCa specimens. Using a genetic modification approach, we identified UBN2 as a downstream target gene of ADAM9 that is critical for the survival of androgen-dependent PCa cells in response to androgen deprivation, through the induction and effect of the aldo-keto reductase family 1 member C3 (AKR1C3). Collectively, our results reveal a novel action of ADAM9 on the transition of androgen-dependent PCa cells into an androgen-independent manner through the UBN2/AKR1C3 axis; the aforementioned action could contribute to the clinically-observed acquired androgen-deprivation therapy resistance.     

Use of two gene panels for prostate cancer diagnosis and patient risk stratification

Currently, no ideal prostate cancer (PCa) diagnostic or prognostic test is available due to the lack of biomarkers with high sensitivity and specificity. There is an unmet medical need to develop combinations of multiple biomarkers which may have higher accuracy in detection of PCa and stratification of aggressive and indolent cancer patients. The aim of this study was to test two biomarker gene panels in distinguishing PCa from benign prostate and high-risk, aggressive PCa from low-risk, indolent PCa, respectively. We identified a five-gene panel that can be used to distinguish PCa from benign prostate. The messenger RNA (mRNA) expression signature of the five genes was determined in 144 PCa and benign prostate specimens from prostatectomy. We showed that the five-gene panel distinguished PCa from benign prostate with sensitivity of 96.59 %, specificity of 92.86 %, and area under the curve (AUC) of 0.992 (p?<?0.0001). The five-gene panel was further validated in a 137 specimen cohort and showed sensitivity of 84.62 %, specificity of 91.84 %, and AUC of 0.942 (p?<?0.0001). To define subtypes of PCa for treatment guidance, we examined mRNA expression signature of an eight-gene panel in 87 PCa specimens from prostatectomy. The signature of the eight-gene panel was able to distinguish aggressive PCa (Gleason score >6) from indolent PCa (Gleason score ≤6) with sensitivity of 90.28 %, specificity of 80.00 %, and AUC of 0.967 (p?<?0.0001). This panel was further validated in a 158 specimen cohort and showed significant difference between aggressive PCa and indolent PCa with sensitivity of 92.57 %, specificity of 70.00 %, and AUC of 0.962 (p?<?0.0001). Our findings in assessing multiple biomarkers in combination may provide new tools to detect PCa and distinguish aggressive and indolent PCa for precision and personalized treatment. The two biomarker panels may be used in clinical settings for accurate PCa diagnosis and patient risk stratification for biomarker-guided treatment.     

Identification of DEK as a potential therapeutic target for neuroendocrine prostate cancer

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer which does not respond to hormone therapy. Research of NEPC has been hampered by a lack of clinically relevant in vivo models. Recently, we developed a first-in-field patient tissue-derived xenograft model of complete neuroendocrine transdifferentiation of prostate adenocarcinoma. By comparing gene expression profiles of a transplantable adenocarcinoma line (LTL331) and its NEPC subline (LTL331R), we identified DEK as a potential biomarker and therapeutic target for NEPC. In the present study, elevated DEK protein expression was observed in all NEPC xenograft models and clinical NEPC cases, as opposed to their benign counterparts (0%), hormonal naïve prostate cancer (2.45%) and castration-resistant prostate cancer (29.55%). Elevated DEK expression was found to be an independent clinical risk factor, associated with shorter disease-free survival of hormonal naïve prostate cancer patients. DEK silencing in PC-3 cells led to a marked reduction in cell proliferation, cell migration and invasion. The results suggest that DEK plays an important role in the progression of prostate cancer, especially to NEPC, and provides a potential biomarker to aid risk stratification of prostate cancer and a novel target for therapy of NEPC.     

Loss of NEIL3 activates radiotherapy resistance in the progression of prostate cancer

Objective:To explore the genetic changes in the progression of castration-resistant prostate cancer (CRPC) and neuroendocrine prostate cancer (NEPC) and the reason why these cancers resist existing therapies.Methods:We employed our CRPC cell line microarray and other CRPC or NEPC datasets to screen the target gene NEIL3. Lentiviral transfection and RNA interference were used to construct overexpression and knockdown cell lines. Cell and animal models of radiotherapy were established by using a medical electron linear accelerator. Flow cytometry was used to detect apoptosis or cell cycle progression. Western blot and qPCR were used to detect changes in the protein and RNA levels.Results:TCGA and clinical patient datasets indicated that NEIL3 was downregulated in CRPC and NEPC cell lines, and NEIL3 was correlated with a high Gleason score but a good prognosis. Further functional studies demonstrated that NEIL3 had no effect on the proliferation and migration of PCa cells. However, cell and animal radiotherapy models revealed that NEIL3 could facilitate the radiotherapy sensitivity of PCa cells, while loss of NEIL3 activated radiotherapy resistance. Mechanistically, we found that NEIL3 negatively regulated the expression of ATR, and higher NEIL3 expression repressed the ATR/CHK1 pathway, thus regulating the cell cycle.Conclusions:We demonstrated that NEIL3 may serve as a diagnostic or therapeutic target for therapy-resistant patients.     

Class III beta-tubulin expression predicts prostate tumor aggressiveness and patient response to docetaxel-based chemotherapy

Expression of class III β-tubulin (βIII-tubulin) correlates with tumor progression and resistance to taxane-based therapies for several human malignancies, but its use as a biomarker of tumor behavior in prostate cancer (PCa) remains largely unexplored. Here, we describe βIII-tubulin immunohistochemical staining patterns of prostate tumors obtained from a broad spectrum of PCa patients, some of whom subsequently received docetaxel therapy for castration-resistant PCa (CRPC). Elevated βIII-tubulin expression was significantly associated with tumor aggressiveness in PCa patients with presumed localized disease, as it was found to be an independent marker of biochemical recurrence after treatment. Additionally, βIII-tubulin expression in tumor cells was an independent predictor of lower overall survival for patients receiving docetaxel-based chemotherapy for CRPC. Manipulation of βIII-tubulin expression in human PCa cell lines using a human βIII-tubulin expression vector or βIII-tubulin small interfering RNA altered cell survival in response to docetaxel treatment in a manner that supports a role for βIII-tubulin expression as a mediator of PCa cell resistance to docetaxel therapy. Our findings suggest a role for βIII-tubulin as candidate theranostic biomarker to predict the response to docetaxel-based chemotherapy as well as to target for treatment of docetaxel-resistant CRPC.     

Clinical and biomarker correlates of androgen-independent, locally aggressive prostate cancer with limited metastatic potential.

PURPOSE: We have identified a subset of patients exhibiting extended survival with metastases from androgenindependent prostate cancer of which the principal site of progression was the tumor primary. The purpose of this study was to evaluate the expression of selected biomarkers to characterize this subset of prostate cancer patients. EXPERIMENTAL DESIGN: A 105 core tissue microarray was constructed from primary tumor samples from 16 patients, with matched lymph node metastases in 5 cases. Immunohistochemistry was used to evaluate selected biomarkers associated with prostate cancer progression. Standard statistical methodologies were used to compute the distribution of time to progression and overall survival associations between pairs of biomarkers. Hierarchical clustering was done between groups of biomarkers, and we devised new methods to assess homogeneity of biomarker expression. RESULTS: The median interval from diagnosis to salvage surgery was 65 months. The profile of biomarker expression was notable for virtual absence of neuroendocrine features, high CD10, low matrix metalloproteinase (MMP)-9, high E-cadherin expression, and high membranous beta-catenin. The mean proliferative index was 12.1 +/- 10.1%, and the mean apoptotic index was 3.48 +/- 2.22%, and there was a significant correlation between these indices. Expression of the epidermal growth factor receptor was associated with phospho-AKT and proliferative index but inversely associated with phospho-STAT3. CONCLUSIONS: The cohort of prostate cancer patients, characterized by locally aggressive disease rather than lethal metastatic progression, was associated with a distinctive biomarker signature. The biomarker profile was, in general, more consistent with low-grade prostate cancer exhibiting local growth rather than metastatic progression. Ongoing studies will establish whether this unique subset of patients can be identified prospectively.     

Molecular characterization of neuroendocrine prostate cancer and identification of new drug targets

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer that most commonly evolves from preexisting prostate adenocarcinoma (PCA). Using Next Generation RNA-sequencing and oligonucleotide arrays, we profiled 7 NEPC, 30 PCA, and 5 benign prostate tissue (BEN), and validated findings on tumors from a large cohort of patients (37 NEPC, 169 PCA, 22 BEN) using IHC and FISH. We discovered significant overexpression and gene amplification of AURKA and MYCN in 40% of NEPC and 5% of PCA, respectively, and evidence that that they cooperate to induce a neuroendocrine phenotype in prostate cells. There was dramatic and enhanced sensitivity of NEPC (and MYCN overexpressing PCA) to Aurora kinase inhibitor therapy both in vitro and in vivo, with complete suppression of neuroendocrine marker expression following treatment. We propose that alterations in Aurora kinase A and N-myc are involved in the development of NEPC, and future clinical trials will help determine from the efficacy of Aurora kinase inhibitor therapy. SIGNIFICANCE: We report on the largest in-depth molecular analysis of NEPC and provide new insight into molecular events involved in the progression of prostate cancer.     

An analysis of a multiple biomarker panel to better predict prostate cancer metastasis after radical prostatectomy

A plethora of individual candidate biomarkers for predicting biochemical relapse in localized prostate cancer (PCa) have been proposed. Combined biomarkers may improve prognostication, and ensuring validation against more clinically relevant endpoints are required. The Australian PCa Research Centre NSW has contributed to numerous studies of molecular biomarkers associated with biochemical relapse. In the current study, these biomarkers were re-analyzed for biochemical relapse, metastatic relapse and PCa death with extended follow-up. Biomarkers of significance were then used to develop a combined prognostic model for clinical outcomes and validated in a large independent cohort. The discovery cohort (n = 324) was based on 12 biomarkers with a median follow-up of 16 years. Seven biomarkers were significantly associated with biochemical relapse. Three biomarkers were associated with metastases: AZGP1, Ki67 and PML. Only AZGP1 was associated with PCa death. In their individual and combinational forms, AZGP1 and Ki67 as a dual BM signature was the most robust predictor of metastatic relapse (AUC 0.762). The AZPG1 and Ki67 signature was validated in an independent cohort of 347 PCa patients. The dual BM signature of AZGP1 and Ki67 predicted metastasis in the univariable (HR 7.2, 95% CI, 1.6–32; p = 0.01) and multivariable analysis (HR 5.4, 95% CI, 1.2–25; p = 0.03). The dual biomarker signature marginally improved risk prediction compared to AZGP1 alone (AUC 0.758 versus 0.738, p < 0.001). Our findings indicate that biochemical relapse is not an adequate surrogate for metastasis or PCa death. The dual biomarker signature of AZGP1 and Ki67 offers a small benefit in predicting metastasis over AZGP1 alone.     

去势治疗诱导的神经内分泌前列腺癌的研究进展*

转移性前列腺癌行去势治疗（androgen-deprivation therapy ,ADT ）后将逐渐发展为去势抵抗性前列腺癌（castration-resistant prostate cancer ,CRPC）。 神经内分泌前列腺癌（neuroendocrine prostate cancer,NEPC）是CRPC的极差预后亚型,多由前列腺癌细胞发生神经内分泌分化（neuroendocrine differentiation ,NED ）引起,放化疗效果较差,平均生存期不到1 年,约占因CRPC患者死亡的25％,目前其分子机制研究较有限。进一步研究NEPC发生的分子机制将为NEPC治疗药物的开发与应用提供新的思路。     

Resetting the Bar of Castration Resistance – Understanding Androgen Dynamics in Therapy Resistance and Treatment Choice in Prostate Cancer

This review discusses impact of advancements in biologic understanding of prostate cancer (PCa) on definition and diagnosis of castration-resistant PCa (CRPC), predictive factors for progression to CRPC and treatment strategies. More sensitive assays confirm that bilateral orchiectomy reduces serum testosterone (T) closer to < 20 ng/dL than < 50 ng/dL, and evidence suggests that achieving T < 20 ng/dL improves outcomes and delays CRPC emergence. Regular T assessments will evaluate whether T is adequately suppressed in the setting of potential progression to CRPC, given that late dosing may result in T escape. More advanced imaging modalities and biomarker assays allow earlier detection of disease progression. Predictive factors for progression to CRPC include Gleason grade, extent of metastatic spread, germline hereditary factors such as gene mutations affecting androgen receptor amplification or DNA repair deficiency mutations, prostate-specific antigen kinetics, and biomarker analyses. Treatment options for CRPC have expanded beyond androgen deprivation therapy to include therapies that suppress T or inhibit its activity through varying mechanisms. Future directions include therapies with novel biological targets, drug combinations and personalized treatments. Advanced PCa management aims to delay progression to CRPC and prolong survival. With redefinition of castration and advancements in understanding of the biology of disease progression, diagnosis and treatment strategies should be re-evaluated. Definition of CRPC could be updated to reflect the T < 20 ng/dL requirement as this is a ‘true’ castrate level and may improve outcomes. It is important that androgen deprivation therapy as foundational therapy is continued even as new CRPC therapies are introduced.     

Epigenomic Alterations in Localized and Advanced Prostate Cancer

Although prostate cancer (PCa) is the second leading cause of cancer death among men worldwide, not all men diagnosed with PCa will die from the disease. A critical challenge, therefore, is to distinguish indolent PCa from more advanced forms to guide appropriate treatment decisions. We used Enhanced Reduced Representation Bisulfite Sequencing, a genome-wide high-coverage single-base resolution DNA methylation method to profile seven localized PCa samples, seven matched benign prostate tissues, and six aggressive castration-resistant prostate cancer (CRPC) samples. We integrated these data with RNA-seq and whole-genome DNA-seq data to comprehensively characterize the PCa methylome, detect changes associated with disease progression, and identify novel candidate prognostic biomarkers. Our analyses revealed the correlation of cytosine guanine dinucleotide island (CGI)-specific hypermethylation with disease severity and association of certain breakpoints (deletion, tandem duplications, and interchromosomal translocations) with DNA methylation. Furthermore, integrative analysis of methylation and single-nucleotide polymorphisms (SNPs) uncovered widespread allele-specific methylation (ASM) for the first time in PCa. We found that most DNA methylation changes occurred in the context of ASM, suggesting that variations in tumor epigenetic landscape of individuals are partly mediated by genetic differences, which may affect PCa disease progression. We further selected a panel of 13 CGIs demonstrating increased DNA methylation with disease progression and validated this panel in an independent cohort of 20 benign prostate tissues, 16 PCa, and 8 aggressive CRPCs. These results warrant clinical evaluation in larger cohorts to help distinguish indolent PCa from advanced disease.     

Paracrine sonic hedgehog signaling contributes significantly to acquired steroidogenesis in the prostate tumor microenvironment

Despite the substantial benefit of androgen deprivation therapy (ADT) for metastatic prostate cancer, patients often progress to castration‐resistant disease (CRPC) that is more difficult to treat. CRPC is associated with renewed androgen receptor activity in tumor cells and restoration of tumor androgen levels through acquired intratumoral steroidogenesis (AIS). Although prostate cancer (PCa) cells have been shown to have steroidogenic capability in vitro, we previously found that benign prostate stromal cells (PrSCs) can also synthesize testosterone (T) from an adrenal precursor, DHEA, when stimulated with a hedgehog (Hh) pathway agonist, SAG. Here, we show exposure of PrSCs to a different Smoothened (Smo) agonist, Ag1.5, or to conditioned medium from sonic hedgehog overexpressing LNCaP cells induces steroidogenic enzyme expression in PrSCs and significantly increases production of T and its precursor steroids in a Smo‐dependent manner from 22‐OH‐cholesterol substrate. Hh agonist‐/ligand‐treated PrSCs produced androgens at a rate similar to or greater than that of PCa cell lines. Likewise, primary bone marrow stromal cells became more steroidogenic and produced T under the influence of Smo agonist. Treatment of mice bearing LNCaP xenografts with a Smo antagonist, TAK‐441, delayed the onset of CRPC after castration and substantially reduced androgen levels in residual tumors. These outcomes support the idea that stromal cells in ADT‐treated primary or metastatic prostate tumors can contribute to AIS as a consequence of a paracrine Hh signaling microenvironment. As such, Smo antagonists may be useful for targeting prostate tumor stromal cell‐derived AIS and delaying the onset of CRPC after ADT.     

Expression of microRNA‐221 is progressively reduced in aggressive prostate cancer and metastasis and predicts clinical recurrence

Emerging evidence shows that microRNAs (miR) are involved in the pathogenesis of a variety of cancers, including prostate carcinoma (PCa). Little information is available regarding miR expression levels in lymph node metastasis of prostate cancer or the potential of miRs as prognostic markers in this disease. Therefore, we analyzed the global expression of miRs in benign, hyperplastic prostate tissue (BPH), primary PCa of a high risk group of PCa patients, and corresponding metastatic tissues by microarray analysis. Consistent with the proposal that some miRs are oncomirs, we found aberrant expression of several miRs, including the downregulation of miR‐221, in PCa metastasis. Downregulation of miR‐221 was negatively correlated with the expression of the proto‐oncogen c‐kit in primary carcinoma. In a large study cohort, the prostate‐specific oncomir miR‐221 was progressively downregulated in aggressive forms of PCa. Downregulation of miR‐221 was associated with clinicopathological parameters, including the Gleason score and the clinical recurrence during follow up. Kaplan–Meier estimates and Cox proportional hazard models showed that miR‐221 downregulation was linked to tumor progression and recurrence in a high risk prostate cancer cohort. Our results showed that progressive miR‐221 downregulation hallmarks metastasis and presents a novel prognostic marker in high risk PCa. This suggests that miR‐221 has potential as a diagnostic marker and therapeutic target in PCa.     

去势抵抗性前列腺癌精准医学研究的探索*

我国前列腺癌发病率呈逐年上升趋势,且大多数前列腺癌患者就诊时已处于中晚期,虽然内分泌治疗可使多数患者的病情在一定程度上能得到控制和改善,但其中绝大多数患者发展为去势抵抗性前列腺癌（castration resistant prostate cancer ,CRPC）。 此类患者预后极差,治疗颇为棘手,因此迫切需要新的治疗策略。精准医学能够根据每位患者的基因特征指导临床个体化治疗。本文就CRPC发病机制和靶向治疗药物的研发、指导个体化治疗的临床试验进行综述,以总结和探讨CRPC精准医学研究的进展。     

A distinct plasma lipid signature associated with poor prognosis in castration‐resistant prostate cancer

Lipids are known to influence tumour growth, inflammation and chemoresistance. However, the association of circulating lipids with the clinical outcome of metastatic castration‐resistant prostate cancer (CRPC) is unknown. We investigated associations between the plasma lipidome and clinical outcome in CRPC. Lipidomic profiling by liquid chromatography‐tandem mass spectrometry was performed on plasma samples from a Phase 1 discovery cohort of 96 CRPC patients. Results were validated in an independent Phase 2 cohort of 63 CRPC patients. Unsupervised analysis of lipidomic profiles (323 lipid species) classified the Phase 1 cohort into two patient subgroups with significant survival differences (HR 2.31, 95% CI 1.44–3.68, p = 0.0005). The levels of 46 lipids were individually prognostic and were predominantly sphingolipids with higher levels associated with poor prognosis. A prognostic three‐lipid signature was derived (ceramide d18:1/24:1, sphingomyelin d18:2/16:0, phosphatidylcholine 16:0/16:0) and was also associated with shorter survival in the Phase 2 cohort (HR 4.8, 95% CI 2.06–11.1, p = 0.0003). The signature was an independent prognostic factor when modelled with clinicopathological factors or metabolic characteristics. The association of plasma lipids with CRPC prognosis suggests a possible role of these lipids in disease progression. Further research is required to determine if therapeutic modulation of the levels of these lipids by targeting their metabolic pathways may improve patient outcome.     

Common structural and epigenetic changes in the genome of castration-resistant prostate cancer

Progression of primary prostate cancer to castration-resistant prostate cancer (CRPC) is associated with numerous genetic and epigenetic alterations that are thought to promote survival at metastatic sites. In this study, we investigated gene copy number and CpG methylation status in CRPC to gain insight into specific pathophysiologic pathways that are active in this advanced form of prostate cancer. Our analysis defined and validated 495 genes exhibiting significant differences in CRPC in gene copy number, including gains in androgen receptor (AR) and losses of PTEN and retinoblastoma 1 (RB1). Significant copy number differences existed between tumors with or without AR gene amplification, including a common loss of AR repressors in AR-unamplified tumors. Simultaneous gene methylation and allelic deletion occurred frequently in RB1 and HSD17B2, the latter of which is involved in testosterone metabolism. Lastly, genomic DNA from most CRPC was hypermethylated compared with benign prostate tissue. Our findings establish a comprehensive methylation signature that couples epigenomic and structural analyses, thereby offering insights into the genomic alterations in CRPC that are associated with a circumvention of hormonal therapy. Genes identified in this integrated genomic study point to new drug targets in CRPC, an incurable disease state which remains the chief therapeutic challenge.     

MicroRNA expression signature of castration-resistant prostate cancer: the microRNA-221/222 cluster functions as a tumour suppressor and disease progression marker

Background:

Our present study of the microRNA (miRNA) expression signature in castration-resistant prostate cancer (CRPC) revealed that the clustered miRNAs microRNA-221 (miR-221) and microRNA-222 (miR-222) are significantly downregulated in cancer tissues. The aim of this study was to investigate the functional roles of miR-221 and miR-222 in prostate cancer (PCa) cells.

Methods:

A CRPC miRNA signature was constructed by PCR-based array methods. Functional studies of differentially expressed miRNAs were analysed using PCa cells. The association between miRNA expression and overall survival was estimated by the Kaplan–Meier method. In silico database and genome-wide gene expression analyses were performed to identify molecular targets regulated by the miR-221/222 cluster.

Results:

miR-221 and miR-222 were significantly downregulated in PCa and CRPC specimens. Kaplan–Meier survival curves showed that low expression of miR-222 predicted a short duration of progression to CRPC. Restoration of miR-221 or miR-222 in cancer cells revealed that both miRNAs significantly inhibited cancer cell migration and invasion. Ecm29 was directly regulated by the miR-221/222 cluster in PCa cells.

Conclusions:

Loss of the tumour-suppressive miR-221/222 cluster enhanced migration and invasion in PCa cells. Our data describing targets regulated by the tumour-suppressive miR-221/222 cluster provide insights into the mechanisms of PCa and CRPC progression.