New advances of the androgen receptor in prostate cancer: report from the 1st International Androgen Receptor Symposium.

The androgen receptor (AR) is a crucial player in various aspects of male reproduction and has been associated with the development and progression of prostate cancer (PCa). Therefore, the protein is the linchpin of current PCa therapies. Despite great research efforts, the AR signaling pathway has still not been deciphered, and the emergence of resistance is still the biggest problem in PCa treatment. To discuss the latest developments in AR research, the "1st International Androgen Receptor Symposium" offered a forum for the exchange of clinical and scientific innovations around the role of the AR in prostate cancer (PCa) and to stimulate new collaborative interactions among leading scientists from basic, translational, and clinical research. The symposium included three sessions covering preclinical studies, prognostic and diagnostic biomarkers, and ongoing prostate cancer clinical trials. In addition, a panel discussion about the future direction of androgen deprivation therapy and anti-AR therapy in PCa was conducted. Therefore, the newest insights and developments in therapeutic strategies and biomarkers are discussed in this report.

The Identification of Small Molecule Inhibitors That Reduce Invasion and Metastasis of Aggressive Cancers.

Transformed epithelial cells can activate programs of epithelial plasticity and switch from a sessile, epithelial phenotype to a motile, mesenchymal phenotype. This process is linked to the acquisition of an invasive phenotype and the formation of distant metastases. The development of compounds that block the acquisition of an invasive phenotype or revert the invasive mesenchymal phenotype into a more differentiated epithelial phenotype represent a promising anticancer strategy. In a high-throughput assay based on E-cadherin (re)induction and the inhibition of tumor cell invasion, 44,475 low molecular weight (LMW) compounds were screened. The screening resulted in the identification of candidate compounds from the PROAM02 class. Selected LMW compounds activated E-cadherin promoter activity and inhibited cancer cell invasion in multiple metastatic human cancer cell lines. The intraperitoneal administration of selected LMW compounds reduced the tumor burden in human prostate and breast cancer in vivo mouse models. Moreover, selected LMW compounds decreased the intra-bone growth of xenografted human prostate cancer cells. This study describes the identification of the PROAM02 class of small molecules that can be exploited to reduce cancer cell invasion and metastases. Further clinical evaluation of selected candidate inhibitors is warranted to address their safety, bioavailability and antitumor efficacy in the management of patients with aggressive cancers.

Reovirus mutant jin-3 exhibits lytic and immune-stimulatory effects in preclinical human prostate cancer models.

Treatment of castration-resistant prostate cancer remains a challenging clinical problem. Despite the promising effects of immunotherapy in other solid cancers, prostate cancer has remained largely unresponsive. Oncolytic viruses represent a promising therapeutic avenue, as oncolytic virus treatment combines tumour cell lysis with activation of the immune system and mounting of effective anti-tumour responses. Mammalian Orthoreoviruses are non-pathogenic human viruses with a preference of lytic replication in human tumour cells. In this study, we evaluated the oncolytic efficacy of the bioselected oncolytic reovirus mutant jin-3 in multiple human prostate cancer models. The jin-3 reovirus displayed efficient infection, replication, and anti-cancer responses in 2D and 3D prostate cancer models, as well as in ex vivo cultured human tumour slices. In addition, the jin-3 reovirus markedly reduced the viability and growth of human cancer cell lines and patient-derived xenografts. The infection induced the expression of mediators of immunogenic cell death, interferon-stimulated genes, and inflammatory cytokines. Taken together, our data demonstrate that the reovirus mutant jin-3 displays tumour tropism, and induces potent oncolytic and immunomodulatory responses in human prostate cancer models. Therefore, jin-3 reovirus represents an attractive candidate for further development as oncolytic agent for treatment of patients with aggressive localised or advanced prostate cancer.

Patient-derived tumour models for personalized therapeutics in urological cancers.

Preclinical knowledge of dysregulated pathways and potential biomarkers for urological cancers has undergone limited translation into the clinic. Moreover, the low approval rate of new anticancer drugs and the heterogeneous drug responses in patients indicate that current preclinical models do not always reflect the complexity of malignant disease. Patient-derived tumour models used in preclinical uro-oncology research include 3D culture systems, organotypic tissue slices and patient-derived xenograft models. Technological innovations have enabled major improvements in the capacity of these tumour models to reproduce the clinical complexity of urological cancers. Each type of patient-derived model has inherent advantages and limitations that can be exploited, either alone or in combination, to gather specific knowledge on clinical challenges and address unmet clinical needs. Nevertheless, few opportunities exist for patients with urological cancers to benefit from personalized therapeutic approaches. Clinical validation of experimental data is needed to facilitate the translation and implementation of preclinical knowledge into treatment decision making.

Cationic amphiphilic drugs as potential anticancer therapy for bladder cancer.

More effective therapy for patients with either muscle-invasive or high-risk non-muscle-invasive urothelial carcinoma of the bladder (UCB) is an unmet clinical need. For this, drug repositioning of clinically approved drugs represents an interesting approach. By repurposing existing drugs, alternative anticancer therapies can be introduced in the clinic relatively fast, because the safety and dosing of these clinically approved pharmacological agents are generally well known. Cationic amphiphilic drugs (CADs) dose-dependently decreased the viability of a panel of human UCB lines in vitro. CADs induced lysosomal puncta formation, a hallmark of lysosomal leakage. Intravesical instillation of the CAD penfluridol in an orthotopic mouse xenograft model of human UCB resulted in significantly reduced intravesical tumor growth and metastatic progression. Furthermore, treatment of patient-derived ex vivo cultured human UCB tissue caused significant partial or complete antitumor responses in 97% of the explanted tumor tissues. In conclusion, penfluridol represents a promising treatment option for bladder cancer patients and warrants further clinical evaluation.

Protocols for Migration and Invasion Studies in Prostate Cancer.

Prostate cancer is the most common malignancy diagnosed in men in the western world. The development of distant metastases and therapy resistance are major clinical problems in the management of prostate cancer patients. In order for prostate cancer to metastasize to distant sites in the human body, prostate cancer cells have to migrate and invade neighboring tissue. Cancer cells can acquire a migratory and invasive phenotype in several ways, including single cell and collective migration. As a requisite for migration, epithelial prostate cancer cells often need to acquire a motile, mesenchymal-like phenotype. This way prostate cancer cells often lose polarity and epithelial characteristics (e.g., expression of E-cadherin homotypic adhesion receptor), and acquire mesenchymal phenotype (for example, cytoskeletal rearrangements, enhanced expression of proteolytic enzymes and other repertory of integrins). This process is referred to as epithelial-to-mesenchymal transition (EMT). Cellular invasion, one of the hallmarks of cancer, is characterized by the movement of cells through a three-dimensional matrix, resulting in remodeling of the cellular environment. Cellular invasion requires adhesion, proteolysis of the extracellular matrix, and migration of cells. Studying the migratory and invasive ability of cells in vitro represents a useful tool to assess the aggressiveness of solid cancers, including those of the prostate.This chapter provides a comprehensive description of the Transwell migration assay, a commonly used technique to investigate the migratory behavior of prostate cancer cells in vitro. Furthermore, we will provide an overview of the adaptations to the Transwell migration protocol to study the invasive capacity of prostate cancer cells, i.e., the Transwell invasion assay. Finally, we will present a detailed description of the procedures required to stain the Transwell filter inserts and quantify the migration and/or invasion.

An ex vivo Tissue Culture Model for the Assessment of Individualized Drug Responses in Prostate and Bladder Cancer.

Urological malignancies, including prostate and bladder carcinoma, represent a major clinical problem due to the frequent occurrence of therapy resistance and the formation of incurable distant metastases. As a result, there is an urgent need for versatile and predictive disease models for the assessment of the individualized drug response in urological malignancies. Compound testing on ex vivo cultured patient-derived tumor tissues could represent a promising approach. In this study, we have optimized an ex vivo culture system of explanted human prostate and bladder tumors derived from clinical specimens and human cancer cell lines xenografted in mice. The explanted and cultured tumor slices remained viable and tissue architecture could be maintained for up to 10 days of culture. Treatment of ex vivo cultured human prostate and bladder cancer tissues with docetaxel and gemcitabine, respectively, resulted in a dose-dependent anti-tumor response. The dose-dependent decrease in tumor cells upon administration of the chemotherapeutic agents was preceded by an induction of apoptosis. The implementation and optimization of the tissue slice technology may facilitate the assessment of anti-tumor efficacies of existing and candidate pharmacological agents in the complex multicellular neoplastic tissues from prostate and bladder cancer patients. Our model represents a versatile "near-patient" tool to determine tumor-targeted and/or stroma-mediated anti-neoplastic responses, thus contributing to the field of personalized therapeutics.

The Effect of Corticosteroids on Human Choroidal Endothelial Cells: A Model to Study Central Serous Chorioretinopathy.

Purpose: To isolate, culture, and characterize primary human choroidal endothelial cells, and to assess their responsiveness to corticosteroids, in order to enable knowledge gain on the pathogenesis of central serous chorioretinopathy. Methods: Choroidal endothelial cells were isolated from cadaveric human donors. Magnetic-activated cell sorting with anti-human CD31 was performed for choroidal endothelial cell isolation. Primary cultures of purified choroidal endothelial cells were treated with several regimens of corticosteroids and analyzed for effects on primary corticosteroid responsive genes. Results: Isolated choroidal endothelial cell cultures had a cobblestone appearance in monolayer cultures and stained positive for vascular endothelial cadherin. Moreover, on a 3D-Matrigel matrix, these cells formed capillary-like structures, characteristic of in vitro endothelial cells. Primary cultures of purified choroidal endothelial cells treated with several regimens of corticosteroids demonstrated significant transcriptional upregulation of primary corticosteroid responsive genes (FKBP5, PER1, GILZ, and SGK1). Further pharmacologic analysis using specific agonists (dexamethasone, aldosterone) and antagonists (mifepristone, spironolactone) for either the glucocorticoid receptor or the mineralocorticoid receptor showed that this response was exclusively mediated by the glucocorticoid receptor in our model. Conclusions: With this optimized choroidal endothelial cell isolation and culturing protocol, we have established an in vitro model that appears very suitable for research on both central serous chorioretinopathy and other diseases in which corticosteroids and choroidal endothelial cells are involved. Our model proves to be suitable for studying effects mediated through the glucocorticoid receptor. The role of mineralocorticoid receptor-mediated effects needs further research, both in vivo and in cell model development.