Altered microRNA (miRNA; miR) expression is associated with tumor formation and progression of various solid cancers. A major challenge in miRNA expression profiling of bulk tumors is represented by the heterogeneity of the subpopulations of cells that constitute the organ, as well as the tumor tissue. Here, we analyzed the expression of miRNAs in a subpopulation of epithelial stem/progenitor-like cells in human prostate cancer [prostate cancer stem cell (PCSC)] and compared their expression profile to more differentiated cancer cells. In both cell lines and clinical prostate cancer specimens, we identified that miR-25 expression in PCSCs was low/absent and steadily increased during their differentiation into cells with a luminal epithelial phenotype. Functional studies revealed that overexpression of miR-25 in prostate cancer cell lines and selected subpopulation of highly metastatic and tumorigenic cells (ALDHhigh) strongly affected the invasive cytoskeleton, causing reduced migration in vitro and metastasis via attenuation of extravasation in vivo. Here, we show, for the first time, that miR-25 can act as a tumor suppressor in highly metastatic PCSCs by direct functional interaction with the 3′-untranslated regions of proinvasive αv- and α6-integrins. Taken together, our observations suggest that miR-25 is a key regulator of invasiveness in human prostate cancer through its direct interactions with αv- and α6-integrin expression. Cancer Res; 75(11); 2326–36. ©2015 AACR.

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.

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.

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.