TNF-alpha is known to induce a strong up-regulation of Fas expression in mouse Sertoli cell cultures, leading to their apoptosis triggered by effector FasL-bearing cells. These data suggest that increased Fas expression on the cell surface might be a key event in the pathogenesis of autoimmune orchitis, by inducing a leakage of the blood-tubular barrier as a consequence of Sertoli cell apoptosis. In the present paper, we have investigated the signal transduction mechanisms involved in the regulation of Fas expression induced by TNF-alpha in mouse Sertoli cells. We studied the role of the transcription factor NF-kappaB and of MAPKs in regulating Fas expression. By using Sertoli cells transfected with a NF-kappaB Luc reporter gene, we proved that TNF-alpha activates the IkappaB/NF-kappaB system. Moreover, the use of the proteasome inhibitor lactacystin led us to demonstrate that NF-kappaB is required for TNF-alpha mediated Fas expression. By using specific inhibitors for each MAPK, we confirmed the pivotal role of the IkappaB/NF-kappaB system by demonstrating that ERKs, p38, and JNK are not involved in Fas up-regulation by TNF-alpha. The comprehension of these pathways could be relevant to the knowledge of the pathogenesis of autoimmune disorders in immune privileged districts of the body.
Toll-like receptors (TLRs) are known to play a key role in the innate immune system particularly in inflammatory response against invading pathogens. Recent reports strongly indicate that they play important roles in cancer cells. Prostate cancer represents one of the most common cancer for which no cure is available once metastatic and androgen refractory. Since TLR3 has been recently suggested as a possible therapeutic target in some cancer cell lines, we studied TLR3 expression and functionality in two human prostate cancer cell lines, LNCaP and PC3. We report that both cell lines express TLR3 and that the TLR3 agonist poly (I:C) activates mitogen-activated protein kinases and induces inhibition of proliferation as well as caspase-dependent apoptosis. By using pharmacological and genetic approaches, we demonstrate the involvement of TLR3 in poly (I:C)-induced effects. We also show that a novel interferon-independent pathway involving protein kinase C (PKC)-α activation, upstream of p38 and c-jun N-terminal kinase, is responsible for poly (I:C) pro-apoptotic effects on LNCaP cells. To our knowledge, this is the first report describing a role of PKC-α in poly (I:C)-mediated apoptosis. The comprehension of the mechanisms underlying TLR3-mediated apoptosis can contribute tools to develop new agonists useful for the treatment of prostate cancer.
RWPE-1 normal prostate cells were tested as an experimental model for adhesion/invasion assays by genotypically and phenotypically characterized community uropathogenic strains of Escherichia coli (UPEC), a frequent cause of urinary tract infections (UTIs) and significant etiologic agent also in bacterial prostatitis. Adhesive ability and strong biofilm production was significantly associated with the bacterial invasive phenotype. Invasive strains derived mainly from male and pediatric patients. This study suggests that such a cell model could usefully integrate other available methods of urovirulence analysis, to deepen knowledge on the bacterial interaction with host cells.
Abstract Toll‐like receptors ( TLR s) are a family of highly conserved transmembrane proteins expressed in epithelial and immune cells that recognize pathogen associated molecular patterns. Besides their role in immune response against infections, numerous studies have shown an important role of different TLR s in cancer, indicating these receptors as potential targets for cancer therapy. We previously demonstrated that the activation of TLR 3 by the synthetic double‐stranded RNA analogue poly I:C induces apoptosis of androgen‐sensitive prostate cancer ( PC a) LNC aP cells and, much less efficiently, of the more aggressive PC 3 cell line. Therefore, in this study we selected LNC aP cells to investigate the mechanism of TLR 3‐mediated apoptosis and the in vivo efficacy of poly I:C‐based therapy. We show that interferon regulatory factor‐3 ( IRF ‐3) signalling plays an essential role in TLR 3‐mediated apoptosis in LNC aP cells through the activation of the intrinsic and extrinsic apoptotic pathways. Interestingly, hardly any apoptosis was induced by poly I:C in normal prostate epithelial cells RWPE ‐1. We also demonstrate for the first time the direct anticancer effect of poly I:C as a single therapeutic agent in a well‐established human androgen‐sensitive PC a xenograft model, by showing that tumour growth is highly impaired in poly I:C‐treated immunodeficient mice. Immunohistochemical analysis of PC a xenografts highlights the antitumour role of poly I:C in vivo both on cancer cells and, indirectly, on endothelial cells. Notably, we show the presence of TLR 3 and IRF ‐3 in both human normal and PC a clinical samples, potentially envisaging poly I:C‐based therapy for PC a.
Toll-like receptor 3 (TLR3) is a key effector of the innate immune system against viruses. Activation of TLR3 exerts an antitumoral effect through a mechanism of action still poorly understood. Here we show that TLR3 activation by polyinosinic:polycytidylic acid induces up-regulation of microRNA-29b, -29c, -148b, and -152 in tumor-derived cell lines and primary tumors. In turn, these microRNAs induce reexpression of epigenetically silenced genes by targeting DNA methyltransferases. In DU145 and TRAMP-C1 prostate and MDA-MB-231 breast cancer cells, we demonstrated that polyinosinic:polycytidylic acid-mediated activation of TLR3 induces microRNAs targeting DNA methyltransferases, leading to demethylation and reexpression of the oncosuppressor retinoic acid receptor beta (RARβ). As a result, cancer cells become sensitive to retinoic acid and undergo apoptosis both in vitro and in vivo. This study provides evidence of an antitumoral mechanism of action upon TLR3 activation and the biological rationale for a combined TLR3 agonist/retinoic acid treatment of prostate and breast cancer.
Abstract Background: Human Dachshund homologue 1 (DACH1) is involved in carcinogenesis with opposite roles reported in different tumor types. Four alternatively spliced transcripts encoding different DACH1 isoforms were described but their specific role in human cancers is still unknown. Prostate cancer (PCa) is a heterogeneous disease with a very wide variability, so there is yet a relevant need to find new diagnostic and therapeutic biomarkers to make a safe clinical evaluation. It is well known that the differential expression of protein isoforms can induce distinct transcriptional programs with opposing effects on tumor progression and therapy. Thus, in this study we aimed to correlate the functional role of DACH1 with its splicing variants expression in PCa. Methods: The expression and functional role of DACH1 splicing variants in PCa were investigated using tumor (PC3) and normal (RWPE-1) cell lines, patient biopsies and TCGA dataset. Flow-cytometry, western blots and RT-qPCR were used for in vitro molecular characterization; invasion, adhesion, clonogenic assays and cell cycle analysis for functional characterization. Immunohystochemistry and western blot were performed on human PCa biopsies. Results: RT-qPCR and Western Blot revealed that DACH1-positive PC3 cells predominantly expressed DACH1 variant 4 (DACH1-v4), whereas RWPE-1 cells mostly expressed DACH1 variant 3. Stable DACH1-v4 overexpression enhanced the transformed phenotype of PC3 cells by inducing proliferation, colony formation, invasion ability, epithelial to mesenchymal transition. Given its intrinsic radioresistance, PCa frequently recurs after radiotherapy. Of note, DACH1-v4-overexpressing PC3 cells displayed higher radioresistant behavior. Overexpression of DACH1-v4 also transformed RWPE-1 cells to oncogenic phenotype, suggesting a pro-oncogenic role for this specific isoform. PCa biopsies analysis showed DACH1 nuclear staining enhanced throughout the increase of the tumor grade. Remarkably, tumor glands were found to express a long DACH1 variant, while normal prostate tissue expressed the short DACH1 isoform, in line with data from TCGA-PRAD analysis and our data in RWPE-1 cells. Conclusions: Our findings highlight the oncogenic role of DACH1-v4 in PCa and suggest that the longer DACH1 variants could be associated to pro-tumor function, while the shortest DACH1 variant would perform tumor suppression. The expression of specific DACH1 isoforms could represent a novel diagnostic/prognostic marker in PCa.
Abstract Toll‐Like receptors ( TLR s) are a family of evolutionary conserved transmembrane proteins that recognize highly conserved molecules in pathogens. TLR ‐expressing cells represent the first line of defence sensing pathogen invasion, triggering innate immune responses and subsequently priming antigen‐specific adaptive immunity. In vitro and in vivo studies on experimental cancer models have shown both anti‐ and pro‐tumoural activity of different TLR s in prostate cancer, indicating these receptors as potential targets for cancer therapy. In this review, we highlight the intriguing duplicity of TLR stimulation by pathogens: their protective role in cases of acute infections, and conversely their negative role in favouring hyperplasia and/or cancer onset, in cases of chronic infections. This review focuses on the role of TLR s in the pathophysiology of prostate infection and cancer by exploring the biological bases of the strict relation between TLR s and prostate cancer. In particular, we highlight the debated question of how reliable mutations or deregulated expression of TLR s are as novel diagnostic or prognostic tools for prostate cancer. So far, the anticancer activity of numerous TLR ligands has been evaluated in clinical trials only in organs other than the prostate. Here we review recent clinical trials based on the most promising TLR agonists in oncology, envisaging a potential application also in prostate cancer therapy.
