Immuno-localization of type-IV collagen in the blood-gas barrier and the epithelial–epithelial cell connections of the avian lung

The terminal respiratory units of the gas exchange tissue of the avian lung, the air capillaries (ACs) and the blood capillaries (BCs), are small and rigid: the basis of this mechanical feature has been highly contentious. Because the strength of the blood-gas barrier (BGB) of the mammalian lung has been attributed to the presence of type-IV collagen (T-IVc), localization of T-IVc in the basement membranes (BM) of the BGB and the epithelial–epithelial cell connections (E-ECCs) of the exchange tissue of the lung of the avian (chicken) lung was performed in order to determine whether it may likewise contribute to the strength of the BGB. T-IVc was localized in both the BM and the E-ECCs. As part of an integrated fibroskeletal scaffold on the lung, T-IVc may directly contribute to the strengths of the ACs and the BCs.     

AGEs in human lens capsule promote the TGFβ2‐mediated EMT of lens epithelial cells: implications for age‐associated fibrosis

Proteins in basement membrane (BM) are long‐lived and accumulate chemical modifications during aging; advanced glycation endproduct (AGE) formation is one such modification. The human lens capsule is a BM secreted by lens epithelial cells. In this study, we have investigated the effect of aging and cataracts on the AGE levels in the human lens capsule and determined their role in the epithelial‐to‐mesenchymal transition (EMT) of lens epithelial cells. EMT occurs during posterior capsule opacification (PCO), also known as secondary cataract formation. We found age‐dependent increases in several AGEs and significantly higher levels in cataractous lens capsules than in normal lens capsules measured by LC‐MS/MS. The TGFβ2‐mediated upregulation of the mRNA levels (by qPCR) of EMT‐associated proteins was significantly enhanced in cells cultured on AGE‐modified BM and human lens capsule compared with those on unmodified proteins. Such responses were also observed for TGFβ1. In the human capsular bag model of PCO, the AGE content of the capsule proteins was correlated with the synthesis of TGFβ2‐mediated α‐smooth muscle actin (αSMA). Taken together, our data imply that AGEs in the lens capsule promote the TGFβ2‐mediated fibrosis of lens epithelial cells during PCO and suggest that AGEs in BMs could have a broader role in aging and diabetes‐associated fibrosis.     

Surface shapes and surrounding environment analysis of single‐ and double‐stranded DNA‐binding proteins in protein‐DNA interface

Protein‐DNA bindings are critical to many biological processes. However, the structural mechanisms underlying these interactions are not fully understood. Here, we analyzed the residues shape (peak, flat, or valley) and the surrounding environment of double‐stranded DNA‐binding proteins (DSBs) and single‐stranded DNA‐binding proteins (SSBs) in protein‐DNA interfaces. In the results, we found that the interface shapes, hydrogen bonds, and the surrounding environment present significant differences between the two kinds of proteins. Built on the investigation results, we constructed a random forest (RF) classifier to distinguish DSBs and SSBs with satisfying performance. In conclusion, we present a novel methodology to characterize protein interfaces, which will deepen our understanding of the specificity of proteins binding to ssDNA (single‐stranded DNA) or dsDNA (double‐stranded DNA). Proteins 2016; 84:979–989. © 2016 Wiley Periodicals, Inc.     

iPSC‐derived mesenchymal stem cells exert SCF‐dependent recovery of cigarette smoke‐induced apoptosis/proliferation imbalance in airway cells

Mesenchymal stem cells (MSCs) have emerged as a potential cell‐based therapy for pulmonary emphysema in animal models. Our previous study demonstrated that human induced pluripotent stem cell–derived MSCs (iPSC‐MSCs) were superior over bone marrow–derived MSCs (BM‐MSCs) in attenuating cigarette smoke (CS)‐induced airspace enlargement possibly through mitochondrial transfer. This study further investigated the effects of iPSC‐MSCs on inflammation, apoptosis, and proliferation in a CS‐exposed rat model and examined the effects of the secreted paracrine factor from MSCs as another possible mechanism in an in vitro model of bronchial epithelial cells. Rats were exposed to 4% CS for 1 hr daily for 56 days. At days 29 and 43, human iPSC‐MSCs or BM‐MSCs were administered intravenously. We observed significant attenuation of CS‐induced elevation of circulating 8‐isoprostane and cytokine‐induced neutrophil chemoattractant‐1 after iPSC‐MSC treatment. In line, a superior capacity of iPSC‐MSCs was also observed in ameliorating CS‐induced infiltration of macrophages and neutrophils and apoptosis/proliferation imbalance in lung sections over BM‐MSCs. In support, the conditioned medium (CdM) from iPSC‐MSCs ameliorated CS medium‐induced apoptosis/proliferation imbalance of bronchial epithelial cells in vitro. Conditioned medium from iPSC‐MSCs contained higher level of stem cell factor (SCF) than that from BM‐MSCs. Deprivation of SCF from iPSC‐MSC‐derived CdM led to a reduction in anti‐apoptotic and pro‐proliferative capacity. Taken together, our data suggest that iPSC‐MSCs may possess anti‐apoptotic/pro‐proliferative capacity in the in vivo and in vitro models of CS‐induced airway cell injury partly through paracrine secretion of SCF.     

Ovine fetal mesenchymal stem cell differentiation to cardiomyocytes,effects of co‐culture,role of small molecules; reversine and 5‐azacytidine

The aim of the present study was to investigate the effect of small molecules: Reversine and 5‐azacytidine (5‐AC), in an indirect co‐culture condition with the cardiac fibroblasts as well as non co‐culture condition, in order to explore the effect of such molecules in the process of differentiation of the ovine bone‐marrow mesenchymal stem cells (BM‐MSCs) towards cardiomyocytes. Surface antigens of the isolated cells were analysed using flow‐cytometry. In addition, following to three passages cells were examined for their differentiation capacity into osteocytes and adipose cells, in order to ensure the mesenchymal origin of the stem cells. Six types of treatments were carried out in the present investigation, such that, in the first treatment BM‐MSCs were cultured for 28 days as control group; the second treatment was composed of culturing ovine fetal cardiac fibroblasts on inserts, aiming to use these inserts for culturing plates which were seeded with BM‐MSCs (Chamber group). As the third treatment, BM‐MSCs were supplemented with 10‐μM 5‐AC and incubated for 48 h. The fourth treatment was composed of supplementing BM‐MSCs with the 600‐nM reversine, incubated for 48 h, and subsequently the incubation was further extended for another 48 h in the presence of 5‐AC. The fifth treatment was composed of supplementing the chamber group with 10‐μM 5‐AC and incubation for 48 h, and the last or the sixth treatment was such that chamber group was supplemented with 600‐nM reversine and an incubation period of 48 h. Following to the incubation, medium was replaced with 10‐μM 5‐AC and further incubated for another round of 48 h. In all treatments, following to addition of the small molecules incubations were carried out for 28 days; same as controls. Expression of cardiac alpha‐actinin was analysed by immunocytochemistry. BM‐MSCs have shown to express CD44 and CD166 along with a weak expression of the CD90, CD34, in addition to CD45. Multilineage differentiation has indicated that BM‐MSCs could differentiate into adipose and osteocytes cells as well. In the treatment 4 it was observed that FGF signalling involved genes and all cardiac‐related genes (ANP, MYH6 and Troponin I) were significantly expressed, except connexin 43 compared to other treatments. All treatments received small molecules, either alone or as a co‐culture were seen to express sarcomeric alpha‐actinin. This finding was partially supported by immunocytochemistry. These results validate that reversine and 5‐AC have an effect on ovine BM‐MSC differentiation into cardiomyocytes. Copyright © 2016 John Wiley & Sons, Ltd.     

LncRNA BDNF‐AS inhibits proliferation,migration, invasion and EMT in oesophageal cancer cells by targeting miR‐214

This study was aimed at exploring the effect of lncRNA BDNF‐AS on cell proliferation, migration, invasion and epithelial‐to‐mesenchymal transition (EMT) of oesophageal cancer (EC) cells. The expression of BDNF‐AS and miR‐214 in tissue samples and cells was measured by qRT‐PCR. The targeted relationship between BDNF‐AS and miR‐214 was analysed by dual‐luciferase reporter assay. After cell transfection, the cell proliferation activity was assessed by MTS method, while the migrating and invading abilities were evaluated by transwell assay. LncRNA BDNF‐AS was remarkably down‐regulated, while miR‐214 was up‐regulated in EC tissues and cells in comparison with normal tissues and cells. Overexpression of BDNF‐AS significantly inhibited the abilities of cell proliferation, migration and invasion as well as the EMT processes of EC cells. The bioinformatics analysis and luciferase assay indicated that BDNF‐AS could be directly bound by miR‐214. Furthermore, overexpression of miR‐214 and BDNF‐AS exerted suppressive influence on EC cell multiplication, migration, invasion and EMT processes. LncRNA BDNF‐AS restrained cell proliferation, migration, invasion and EMT processes in EC cells by targeting miR‐214.     

In vitro effects of 2‐methoxyestradiol‐bis‐sulphamate on the non‐tumorigenic MCF‐12A cell line

A priority in recent anti‐cancer drug development has been attaining better side‐effect profiles for potential compounds. To produce highly specific cancer therapies it is necessary to understand both the effects of the proposed compound on cancer and on normal cells comprising the rest of the human body. Thus in vitro evaluation of these compounds against non‐carcinogenic cell lines is of critical importance. One of the most recent developments in experimental anti‐cancer agents is 2‐methoxyestradiol‐bis‐sulphamate (2ME‐BM), a sulphamoylated derivative of 2‐methoxyestradiol. The aim of this study was to evaluate the in vitro effects of 2ME‐BM on cell proliferation, morphology and mechanisms of cell death in the non‐carcinogenic MCF‐12A breast epithelial cell line. The study revealed changes in proliferative capacity, morphology and cell death induction in response to 2ME‐BM exposure (24 h at 0.4 µM). Microscopy showed decreased cell density and cell death‐associated morphology (increased apoptotic characteristics), a slight increase in acidic intracellular vesicles and insignificant ultra‐structural aberrations. Mitotic indices revealed a G₂M‐phase cell cycle block. This was confirmed by flow cytometry, where an increased fraction of abnormal cells and a decrease in cyclin B1 levels were observed. These results evidently demonstrate that the non‐carcinogenic MCF‐12A cell line is less susceptible when compared to 2ME‐BM‐exposed cancer cell lines previously tested. Further in vitro research into the mechanism of this potentially useful compound is warranted. Copyright © 2010 John Wiley & Sons, Ltd.     

An Efficient Ultra‐Flexible Photo‐Charging System Integrating Organic Photovoltaics and Supercapacitors

Flexible and biocompatible integrated photo‐charging devices consisting of photovoltaic cells and energy storage units can provide an independent power supply for next‐generation wearable electronics or biomedical devices. However, current flexible integrated devices exhibit low total energy conversion and storage efficiency and large device thickness, hindering their applicability towards efficient and stable self‐powered systems. Here, a highly efficient and ultra‐thin photo‐charging device with a total efficiency approaching 6% and a thickness below 50 µm is reported, prepared by integrating 3‐µm‐thick organic photovoltaics on 40 µm‐thick carbon nanotube/polymer‐based supercapacitors. This flexible photo‐charging capacitor delivers much higher performance compared with previous reports by tuning the electrochemical properties of the composite electrodes, which reduce the device thickness to 1/8 while improving the total efficiency by 15%. The devices also exhibit a superior operational stability (over 96% efficiency retention after 100 charge/discharge cycles for one week) and mechanical robustness (94.66% efficiency retention after 5000 times bending at a radius of around 2 mm), providing a high‐power and long‐term operational energy source for flexible and wearable electronics.     

WIPF2 promotes Shigella flexneri actin‐based motility and cell‐to‐cell spread

Shigella flexneri is an intracellular pathogen that disseminates in colonic epithelial cells through actin‐based motility and formation of membrane protrusions at cell–cell contacts, that project into adjacent cells and resolve into vacuoles, from which the pathogen escapes, thereby achieving cell‐to‐cell spread. Actin nucleation at the bacterial pole relies on the recruitment of the nucleation‐promoting factor N‐WASP, which activates the actin nucleator ARP2/3. In cells, the vast majority of N‐WASP exists as a complex with WIP. The involvement of WIP in N‐WASP‐dependent actin‐based motility of various pathogens, including vaccinia virus and S. flexneri, has been highly controversial. Here, we show that WIPF2 was the only WIP family member expressed in the human colonic epithelial cell line HT‐29, and its depletion impaired S. flexneri dissemination. WIPF2 depletion increased the number of cytosolic bacteria lacking actin tails (non‐motile) and decreased the velocity of motile bacteria. This correlated with a decrease in the recruitment of N‐WASP to the bacterial pole, and among N‐WASP‐positive bacteria, a decrease in actin tail‐positive bacteria, suggesting that WIPF2 is required for N‐WASP recruitment and activation at the bacterial pole. In addition, when motile bacteria formed protrusions, WIPF2 depletion decreased the number of membrane protrusions that successfully resolved into vacuoles.     

Bone marrow‐derived mesenchymal stem cells enhance autophagy via PI3K/AKT signalling to reduce the severity of ischaemia/reperfusion‐induced lung injury

Autophagy, a type II programmed cell death, is essential for cell survival under stress, e.g. lung injury, and bone marrow‐derived mesenchymal stem cells (BM‐MSCs) have great potential for cell therapy. However, the mechanisms underlying the BM‐MSC activation of autophagy to provide a therapeutic effect in ischaemia/reperfusion‐induced lung injury (IRI) remain unclear. Thus, we investigate the activation of autophagy in IRI following transplantation with BM‐MSCs. Seventy mice were pre‐treated with BM‐MSCs before they underwent lung IRI surgery in vivo. Human pulmonary micro‐vascular endothelial cells (HPMVECs) were pre‐conditioned with BM‐MSCs by oxygen‐glucose deprivation/reoxygenation (OGD) in vitro. Expression markers for autophagy and the phosphoinositide 3‐kinase/protein kinase B (PI3K/Akt) signalling pathway were analysed. In IRI‐treated mice, administration of BM‐MSCs significantly attenuated lung injury and inflammation, and increased the level of autophagy. In OGD‐treated HPMVECs, co‐culture with BM‐MSCs attenuated endothelial permeability by decreasing the level of cell death and enhanced autophagic activation. Moreover, administration of BM‐MSCs decreased the level of PI3K class I and p‐Akt while the expression of PI3K class III was increased. Finally, BM‐MSCs‐induced autophagic activity was prevented using the inhibitor LY294002. Administration of BM‐MSCs attenuated lung injury by improving the autophagy level via the PI3K/Akt signalling pathway. These findings provide further understanding of the mechanisms related to BM‐MSCs and will help to develop new cell‐based therapeutic strategies in lung injury.     

Exosomes Derived from the Human Primary Colorectal Cancer Cell Line SW480 Orchestrate Fibroblast‐Led Cancer Invasion

In localized tumors, basement membrane (BM) prevents invasive outgrowth of tumor cells into surrounding tissues. When carcinomas become invasive, cancer cells either degrade BM or reprogram stromal fibroblasts to breach BM barrier and lead invasion of cancer cells into surrounding tissues in a process called fibroblast‐led invasion. However, tumor‐derived factors orchestrating fibroblast‐led invasion remain poorly understood. Here it is shown that although early‐stage primary colorectal adenocarcinoma (SW480) cells are themselves unable to invade Matrigel matrix, they secrete exosomes that reprogram normal fibroblasts to acquire de novo capacity to invade matrix and lead invasion of SW480 cells. Strikingly, cancer cells follow leading fibroblasts as collective epithelial‐clusters, thereby circumventing need for epithelial to mesenchymal transition, a key event associated with invasion. Moreover, acquisition of pro‐invasive phenotype by fibroblasts treated with SW480‐derived exosomes relied on exosome‐mediated MAPK pathway activation. Mass spectrometry‐based protein profiling reveals that cancer exosomes upregulate fibroblasts proteins implicated in focal adhesion (ITGA2/A6/AV, ITGB1/B4/B5, EGFR, CRK), regulators of actin cytoskeleton (RAC1, ARF1, ARPC3, CYFIP1, NCKAP1, ICAM1, ERM complex), and signalling pathways (MAPK, Rap1, RAC1, Ras) important in pro‐invasive remodeling of extracellular matrix. Blocking tumor exosome‐mediated signaling to fibroblasts therefore represents an attractive therapeutic strategy in restraining tumors by perturbing stroma‐driven invasive outgrowth.     

Down‐regulating Myoferlin inhibits the vasculogenic mimicry of melanoma via decreasing MMP‐2 and inducing mesenchymal‐to‐epithelial transition

Vasculogenic mimicry (VM) constitutes a novel approach for tumour blood supply and contributes to tumour metastasis and poor prognosis in patients with melanoma. Myoferlin (MYOF), a type II membrane protein involved in membrane regeneration and repair, is elevated in several malignant tumours, especially in advanced melanomas. This study aims to investigate the role and mechanism of MYOF in the regulation of VM. VM structures were found in 14 of 52 tested melanoma samples, and high MYOF expression correlated with VM structures. According to Kaplan–Meier survival curves, VM channels and elevated MYOF expression both correlated with poor prognosis in melanoma patients. Down‐regulation of MYOF by siRNA severely impaired the capability of A375 cells to form VM structures in vitro. Further studies demonstrated MYOF knockdown inhibited cell migration and invasion, which is required for VM formation, via decreasing MMP‐2 expression as evidenced by Western blotting, RT‐RCP and ELISA results. SB‐3CT, a specific inhibitor of MMP‐2, showed similar inhibiting effects with siMYOF, further supporting that MYOF down‐regulation inhibits MMP‐2 expression to affect VM formation. Moreover, MYOF knockdown suppress VM formation by A375 cells by inducing mesenchymal‐to‐epithelial transition (MET). After down‐regulating MYOF, focal adhesions were enlarged and A375 cells developed into a clear epithelial morphology. Such cells acquired the expression of E‐cadherin at adherens junctions along with a loss of mesenchymal markers, such as Vimentin and Twist1. In conclusion, MYOF plays an important role in VM and knockdown of MYOF suppresses VM formation via decreasing MMP‐2 and inducing MET in A375 melanoma cells.     

Structural centrosome aberrations promote non‐cell‐autonomous invasiveness

Centrosomes are the main microtubule‐organizing centers of animal cells. Although centrosome aberrations are common in tumors, their consequences remain subject to debate. Here, we studied the impact of structural centrosome aberrations, induced by deregulated expression of ninein‐like protein (NLP), on epithelial spheres grown in Matrigel matrices. We demonstrate that NLP‐induced structural centrosome aberrations trigger the escape (“budding”) of living cells from epithelia. Remarkably, all cells disseminating into the matrix were undergoing mitosis. This invasive behavior reflects a novel mechanism that depends on the acquisition of two distinct properties. First, NLP‐induced centrosome aberrations trigger a re‐organization of the cytoskeleton, which stabilizes microtubules and weakens E‐cadherin junctions during mitosis. Second, atomic force microscopy reveals that cells harboring these centrosome aberrations display increased stiffness. As a consequence, mitotic cells are pushed out of mosaic epithelia, particularly if they lack centrosome aberrations. We conclude that centrosome aberrations can trigger cell dissemination through a novel, non‐cell‐autonomous mechanism, raising the prospect that centrosome aberrations contribute to the dissemination of metastatic cells harboring normal centrosomes.     

A Two‐Resonance Tapping Cavity for an Optimal Light Trapping in Thin‐Film Solar Cells

An optimal photon absorption in thin film photovoltaic technologies can only be reached by effectively trapping the light in the absorber layer provided a considerable portion of the photons is rejected or scattered out of such layer. Here, a new optical cavity is proposed that can be made to have a resonant character at two different nonharmonic frequencies when adjusting the materials or geometry configurations of the partially transmitting cavity layers. Specific configurations are found where a reminiscence of such two fundamental resonances coexists leading to a broadband light trapping. When a PTB7‐Th:PC₇₁BM organic cell is integrated within such cavity, a power conversion efficiency of 11.1% is measured. This study also demonstrates that when materials alternative to organics are used in the photoactive cell layer, a similar cavity can be implemented to also obtain the largest light absorption possible. Indeed, when it is applied to perovskite cells, an external quantum efficiency is predicted that closely matches its corresponding internal one for a broad wavelength range.     

Role of the ESCRT‐III complex in controlling integrity of the Salmonella‐containing vacuole

Intracellular pathogens need to establish specialised niches for survival and proliferation in host cells. The enteropathogen Salmonella enterica accomplishes this by extensive reorganisation of the host endosomal system deploying the SPI2‐encoded type III secretion system (SPI2‐T3SS). Fusion events of endosomal compartments with the Salmonella‐containing vacuole (SCV) form elaborate membrane networks within host cells enabling intracellular nutrition. However, which host compartments exactly are involved in this process and how the integrity of Salmonella‐modified membranes is accomplished are not fully resolved. An RNA interference knockdown screen of host factors involved in cellular logistics identified the ESCRT (endosomal sorting complex required for transport) system as important for proper formation and integrity of the SCV in infected epithelial cells. We demonstrate that subunits of the ESCRT‐III complex are specifically recruited to the SCV and membrane network. To investigate the role of ESCRT‐III for the intracellular lifestyle of Salmonella, a CHMP3 knockout cell line was generated. Infected CHMP3 knockout cells formed amorphous, bulky SCV. Salmonella within these amorphous SCV were in contact with host cell cytosol, and the attenuation of an SPI2‐T3SS‐deficient mutant strain was partially abrogated. ESCRT‐dependent endolysosomal repair mechanisms have recently been described for other intracellular pathogens, and we hypothesise that minor damages of the SCV during bacterial proliferation are repaired by the action of ESCRT‐III recruitment in Salmonella‐infected host cells.     

Low concentration of anti‐7,8‐dihydroxy‐9,10‐epoxy‐7,8,9,10‐tetrahydrobenzo[a]pyrene induces alterations of extracellular protein profile of exposed epithelial cells

7,8‐Dihydroxy‐9,10‐epoxy‐7,8,9,10‐tetrahydrobenzo[a]pyrene (BPDE) exposure induces adduct formation and oxidative damage on DNA, and consequently triggers complicated stress responses, including such responses as signaling pathway activation, cell cycle arrest, DNA repair, translesion DNA synthesis and mutagenesis. In the present study, 2‐DE and MALDI‐TOF MS were employed to analyze the differential extracellular protein patterns of human amniotic epithelial cells (FL cells) after exposure to 5 nM BPDE and control. As a result, one protein spot that appeared in the culture medium of BPDE treatment group was successfully identified as 14‐3‐3ζ, and three up‐regulated protein spots were identified as annexin A3, annexin V and hydroxypyruvate isomerase homolog. Among them, 14‐3‐3ζ was further detected in some pleural fluid specimens also. These results demonstrate that BPDE exposure can induce alterations of extracellular protein profiles of exposed cells, which may be served as a starting point for searching candidate biomarkers for benzo[a]pyrene exposure.     

Laminin‐332–β1 integrin interactions negatively regulate invadopodia

Adhesion of epithelial cells to basement membranes (BM) occurs through two major structures: actin‐associated focal contacts and keratin‐associated hemidesmosomes, both of which form on laminin‐332 (Ln‐332). In epithelial‐derived cancer cells, additional actin‐linked structures with putative adhesive properties, invadopodia, are frequently present and mediate BM degradation. A recent study proposed that BM invasion requires a proper combination of focal contacts and invadopodia for invading cells to gain traction through degraded BM, and suggested that these structures may compete for common molecular components such as Src kinase. In this study, we tested the role of the Ln‐332 in regulating invadopodia in 804G rat bladder carcinoma cells, a cell line that secretes Ln‐332 and forms all three types of adhesions. Expression of shRNA to Ln‐332 γ2 chain (γ2‐kd) led to increased numbers of invadopodia and enhanced extracellular matrix degradation. Replating γ2‐kd cells on Ln‐332 or collagen‐I fully recovered cell spreading and inhibition of invadopodia. Inhibition of α3 or β1, but not α6 or β4, phenocopied the effect of γ2‐kd, suggesting that α3β1‐mediated focal contacts, rather than α6β4‐mediated hemidesmosome pathways, intersect with invadopodia regulation. γ2‐kd cells exhibited alterations in focal contact‐type structures and in activation of focal adhesion kinase (FAK) and Src kinase. Inhibition of FAK also increased invadopodia number, which was reversible with Src inhibition. These data are consistent with a model whereby actin‐based adhesions can limit the availability of active Src that is capable of invadopodia initiation and identifies Ln‐332‐β1 interactions as a potent upstream regulator that limits cell invasion. J. Cell. Physiol. 223: 134–142, 2010. © 2009 Wiley‐Liss, Inc.     

TLR3 engagement induces IRF‐3‐dependent apoptosis in androgen‐sensitive prostate cancer cells and inhibits tumour growth in vivo

Toll‐like receptors (TLRs) 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 TLRs in cancer, indicating these receptors as potential targets for cancer therapy. We previously demonstrated that the activation of TLR3 by the synthetic double‐stranded RNA analogue poly I:C induces apoptosis of androgen‐sensitive prostate cancer (PCa) LNCaP cells and, much less efficiently, of the more aggressive PC3 cell line. Therefore, in this study we selected LNCaP cells to investigate the mechanism of TLR3‐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 TLR3‐mediated apoptosis in LNCaP 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 PCa xenograft model, by showing that tumour growth is highly impaired in poly I:C‐treated immunodeficient mice. Immunohistochemical analysis of PCa 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 TLR3 and IRF‐3 in both human normal and PCa clinical samples, potentially envisaging poly I:C‐based therapy for PCa.