Docetaxel is a standard chemotherapy for patients with metastatic prostate cancer. However, the response is rather limited and not all of the patients benefit from this treatment. To uncover key mechanisms of docetaxel insensitivity in prostate cancer, we have established docetaxel-resistant sublines. In this study, we report that docetaxel-resistant cells underwent an epithelial-to-mesenchymal transition during the selection process, leading to diminished E-cadherin levels and up-regulation of mesenchymal markers. Screening for key regulators of an epithelial phenotype revealed a significantly reduced expression of microRNA (miR)-200c and miR-205 in docetaxel-resistant cells. Transfection of either microRNA (miRNA) resulted in re-expression of E-cadherin. Functional assays confirmed reduced adhesive and increased invasive and migratory abilities. Furthermore, we detected an increased subpopulation with stem cell-like properties in resistant cells. Tissue microarray analysis revealed a reduced E-cadherin expression in tumors after neoadjuvant chemotherapy. Low E-cadherin levels could be linked to tumor relapse. The present study uncovers epithelial-to-mesenchymal transition as a hallmark of docetaxel resistance. Therefore, we suggest that this mechanism is at least in part responsible for chemotherapy failure, with implications for the development of novel therapeutics.

It is hypothesized that ligand-independent activation of the androgen receptor is one of the mechanisms implicated in tumour progression. However, supportive evidence is limited to the effect of HER-2/neu that stimulates prostate cancer progression through activation of the androgen receptor. In the present study, we have asked whether the proinflammatory cytokine interleukin-6 (IL-6), which is known to stimulate androgen receptor activity and expression of its downstream target genes, may also induce growth of androgen-sensitive cells. We have found that IL-6 differentially regulates proliferation of LAPC-4 and MDA PCa 2b cells. In MDA PCa 2b cells, growth stimulation by IL-6 was reversed by administration of either the non-steroidal anti-androgen bicalutamide or the inhibitor of the mitogen-activated protein kinase pathway PD98059. Neither cell line was found to express endogenous IL-6. Interestingly, the treatment of those prostate cancer cells did not increase phosphorylation of STAT3. The effect of IL-6 on stimulation of androgen receptor activity in MDA PCa 2b cells was lower than that of androgen, comparable with findings reported by other researchers. However, growth of MDA PCa 2b xenografts in castrated animals treated with IL-6 was similar to that in non-castrated animals. In addition, bicalutamide showed an inhibitory effect on IL-6-regulated growth in vivo. Taken together, data in the present study demonstrate that IL-6 may cause growth of androgen receptor-positive tumours in vitro and in vivo through activation of the androgen receptor.

The potent immunomodulator FTY720 elicits immunosuppression via acting on sphingosine 1‐phosphate receptors (S1PR), thereby leading to an entrapment of lymphocytes in the secondary lymphoid tissue. To elucidate the potential in vitro effects of this drug on human monocyte‐derived DC, we used low nanomolar therapeutic concentrations of FTY720 and phosphorylated FTY720 (FTY720‐P) and investigated their influence on DC surface marker expression, protein levels of S1PR and DC effector functions: antigen uptake, chemotaxis, cytokine production, allostimulatory and Th‐priming capacity. We report that both FTY720 and FTY720‐P reduce chemotaxis of immature and mature DC. Mature DC generated in the presence of FTY720 or FTY720‐P showed an impaired immunostimmulatory capacity and reduced IL‐12 but increased IL‐10 production. T cells cultured in the presence of FTY720‐ or FTY720‐P‐treated DC showed an altered cytokine production profile indicating a shift from Th1 toward Th2 differentiation. In treated immature and mature DC, expression levels for two S1PR proteins, S1P₁ and S1P_4, were reduced. We conclude that in vitro treatment with FTY720 affects DC features that are essential for serving their role as antigen‐presenting cells. This might represent a new aspect of the overall immunosuppressive action of FTY720 and makes DC potential targets of further sphingolipid‐derived drugs.

Background: Androgen receptor targeted therapies have emerged as an effective tool to manage advanced prostate cancer (PCa). Nevertheless, frequent occurrence of therapy resistance represents a major challenge in the clinical management of patients, also because the molecular mechanisms behind therapy resistance are not yet fully understood. In the present study, we therefore aimed to identify novel targets to intervene with therapy resistance using gene expression analysis of PCa co-culture spheroids where PCa cells are grown in the presence of cancer-associated fibroblasts (CAFs) and which have been previously shown to be a reliable model for antiandrogen resistance. Methods: Gene expression changes of co-culture spheroids (LNCaP and DuCaP seeded together with CAFs) were identified by Illumina microarray profiling. Real-time PCR, Western blotting, immunohistochemistry and cell viability assays in 2D and 3D culture were performed to validate the expression of selected targets in vitro and in vivo. Cytokine profiling was conducted to analyze CAF-conditioned medium. Results: Gene expression analysis of co-culture spheroids revealed that CAFs induced a significant upregulation of cholesterol and steroid biosynthesis pathways in PCa cells. Cytokine profiling revealed high amounts of pro-inflammatory, pro-migratory and pro-angiogenic factors in the CAF supernatant. In particular, two genes, 3-hydroxy-3-methylglutaryl-Coenzyme A synthase 2 (HMGCS2) and aldo-keto reductase family 1 member C3 (AKR1C3), were significantly upregulated in PCa cells upon co-culture with CAFs. Both enzymes were also significantly increased in human PCa compared to benign tissue with AKR1C3 expression even being associated with Gleason score and metastatic status. Inhibiting HMGCS2 and AKR1C3 resulted in significant growth retardation of co-culture spheroids as well as of various castration and enzalutamide resistant cell lines in 2D and 3D culture, underscoring their putative role in PCa. Importantly, dual targeting of cholesterol and steroid biosynthesis with simvastatin, a commonly prescribed cholesterol synthesis inhibitor, and an inhibitor against AKR1C3 had the strongest growth inhibitory effect. Conclusions: From our results we conclude that CAFs induce an upregulation of cholesterol and steroid biosynthesis in PCa cells, driving them into AR targeted therapy resistance. Blocking both pathways with simvastatin and an AKR1C3 inhibitor may therefore be a promising approach to overcome resistances to AR targeted therapies in PCa.

Prostate cancer (PCa) is one of the most common causes of male cancer-related death in Western nations. The cellular response to androgens is mediated via the androgen receptor (AR), a ligand-inducible transcription factor whose dysregulation plays a key role during PCa development and progression following androgen deprivation therapy, the current mainstay systemic treatment for advanced PCa. Thus, a better understanding of AR signaling and new strategies to abrogate AR activity are essential for improved therapeutic intervention. Consequently, a large number of experimental cell culture models have been established to facilitatein vitroinvestigations into the role of AR signaling in PCa development and progression. These different model systems mimic distinct stages of this heterogeneous disease and exhibit differences with respect to AR expression/status and androgen responsiveness. Technological advances have facilitated the development ofin vitrosystems that more closely reflect the physiological setting, for example via the use of three-dimensional coculture to study the interaction of prostate epithelial cells with the stroma, endothelium, immune system and tissue matrix environment. This review provides an overview of the most commonly usedin vitrocell models currently available to study AR signaling with particular focus on their use in addressing key questions relating to the development and progression of PCa. It is hoped that the continued development ofin vitromodels will provide more biologically relevant platforms for mechanistic studies, drug discovery and design ensuring a more rapid transfer of knowledge from the laboratory to the clinic.

In an interesting study, authors from Austria attempted to elucidate how often detrusor overactivity persists after TURP, and if perfusion of the lower urinary tract influences the outcome. They found that increased vascular resistance of the bladder vessels leads to reduced perfusion, and provide a possible explanation for the persistent symptoms. In a multicentre, community‐based randomized study conducted in the USA and UK, the transdermal oxybutynin system improved the quality of life in adults with overactive bladder. The final paper in this section is from Turkey, presenting the long‐term results of transurethral vaporisation using plasmakinetic energy. OBJECTIVES: To elucidate, in patients with benign prostatic hyperplasia (BPH), how often detrusor overactivity (DOA) is persistent after transurethral resection of the prostate (TURP) and if perfusion of the lower urinary tract influences postoperative outcomes. PATIENTS AND METHODS: Fifty men with urodynamically confirmed DOA and bladder outlet obstruction due to BPH had a TURP. Before and 1 year after TURP the International Prostate Symptom Score (IPSS), quality of life (QoL) score, prostate‐specific antigen (PSA) level and total prostatic volume (TPV) were evaluated. Also, the lower urinary tract was evaluated using pressure‐flow studies and transrectal colour Doppler ultrasonography to assess the vascular resistive index (RI) as a variable of the perfusion of the lower urinary tract. RESULTS: After TURP the IPSS, QoL score, PSA level and TPV decreased. Cystometric measurements showed that in 15 (30%) patients DOA was persistent after TURP. The mean ( sd ) maximum urinary flow rate increased from 9.20 (4.03) to 15.98 (4.62) mL/s and postvoiding residual urine volumes decreased from 109.38 (73.71) to 29.24 (45.00) mL. When men with persistent DOA (15 patients; group 1) were compared with those with no DOA after TURP (35; group 2) there was a statistically significantly higher RI of the bladder vessels in group 1, at 0.86 (0.068) than in group 2, at 0.68 ( 0.055) ( P < 0.001). CONCLUSIONS: Persistent DOA in men after TURP seems to be associated with increased vascular resistance of the bladder vessels with subsequent reduced perfusion and hypoxia.