Explore the vast range of titles available.

It has been known for some time that laminins containing [alpha]1 and [alpha]2 chains, which are normally restricted to the mesangial matrix, accumulate in the glomerular basement membranes (GBM) of Alport mice, dogs, and humans. We show that laminins containing the [alpha]2 chain, but not those containing the [alpha]1 chain activates focal adhesion kinase (FAK) on glomerular podocytes in vitro and in vivo. CD151-null mice, which have weakened podocyte adhesion to the GBM rendering these mice more susceptible to biomechanical strain in the glomerulus, also show progressive accumulation of [alpha]2 laminins in the GBM, and podocyte FAK activation. Analysis of glomerular mRNA from both models demonstrates significant induction of MMP-9, MMP-10, MMP-12, MMPs linked to GBM destruction in Alport disease models, as well as the pro-inflammatory cytokine IL-6. SiRNA knockdown of FAK in cultured podocytes significantly reduced expression of MMP-9, MMP-10 and IL-6, but not MMP-12. Treatment of Alport mice with TAE226, a small molecule inhibitor of FAK activation, ameliorated fibrosis and glomerulosclerosis, significantly reduced proteinuria and blood urea nitrogen levels, and partially restored GBM ultrastructure. Glomerular expression of MMP-9, MMP-10 and MMP-12 mRNAs was significantly reduced in TAE226 treated animals. Collectively, this work identifies laminin [alpha]2-mediated FAK activation in podocytes as an important early event in Alport glomerular pathogenesis and suggests that FAK inhibitors, if safe formulations can be developed, might be employed as a novel therapeutic approach for treating Alport renal disease in its early stages.

Acute lymphoblastic leukaemia (ALL) has a marked propensity to metastasize to the central nervous system (CNS). In contrast to brain metastases from solid tumours, metastases of ALL seldom involve the parenchyma but are isolated to the leptomeninges, which is an infrequent site for carcinomatous invasion. Although metastasis to the CNS occurs across all subtypes of ALL, a unifying mechanism for invasion has not yet been determined. Here we show that ALL cells in the circulation are unable to breach the blood–brain barrier in mice; instead, they migrate into the CNS along vessels that pass directly between vertebral or calvarial bone marrow and the subarachnoid space. The basement membrane of these bridging vessels is enriched in laminin, which is known to coordinate pathfinding of neuronal progenitor cells in the CNS. The laminin receptor α6 integrin is expressed in most cases of ALL. We found that α6 integrin–laminin interactions mediated the migration of ALL cells towards the cerebrospinal fluid in vitro. Mice with ALL xenografts were treated with either a PI3Kδ inhibitor, which decreased α6 integrin expression on ALL cells, or specific α6 integrin-neutralizing antibodies and showed significant reductions in ALL transit along bridging vessels, blast counts in the cerebrospinal fluid and CNS disease symptoms despite minimally decreased bone marrow disease burden. Our data suggest that α6 integrin expression, which is common in ALL, allows cells to use neural migratory pathways to invade the CNS. Expression of α6 integrin enables acute lymphoblastic leukaemia cells to use neural migratory pathways to invade the central nervous system and metastasize to the brain.

The poor prognosis of patients with pancreatic ductal adenocarcinoma (PDAC) is primarily due to the invasive and metastatic behaviors of this disease. Laminin-332 (LM-332) is a key component of the basement membrane barrier, and is associated with tumor metastasis. The present study provides evidence towards the potential function of LM-332 in carcinoma, indicating the distinct roles of the three LM-332 subunits (α3, β3 and γ2) in cell proliferation, migration, invasion, apoptosis and the epithelial-to-mesenchymal transition (EMT) in cancer. The roles of the α3, β3 and γ2 subunits in the malignant biological behavior of PDAC were investigated in the present study. It was revealed that the α3, β3 and γ2 subunits were upregulated in PDAC. Inhibition of all LM-332 subunits abrogated the tumorigenic outcomes, which included cell proliferation, apoptosis, invasion, migration and EMT in vitro. However, the three LM-332 subunits had different degrees of effects on biological behavior. It was observed that LAMA3 (α3) had a stronger effect on cell proliferation, migration and invasion. In addition, LAMB3 (β3) knockdown significantly increased E-cadherin levels and decreased vimentin levels, indicating that LAMB3 was associated with EMT. Likewise, LAMC2 (γ2) mediated proliferation, apoptosis, invasion and migration. However, small interfering (si)-LAMC2 promoted the progression of EMT, which was the opposite effect to that of si-LAMB3. The LM-332 subunits (α3, β3 and γ2) may be novel therapeutic targets of PDAC in the future.

Netrin-4 is a tumor suppressor that interferes with formation of the laminin lattice. We employed cryo-electron microscopy to determine a structure of the protein complex consisting of the N-terminal fragments from netrin-4 and laminin γ1. The structure reveals that netrin-4 binds laminin γ1 at the molecular interface where laminin β1 would have bound, thus inhibiting the assembly of the heterotrimeric laminin polymer nodes consisting of α1, β1, and γ1 subunits, and their polymerization into the extracellular lattice. The four orders of magnitude higher affinity of the netrin-4-laminin γ1 interaction results from the larger buried surface area than the one formed by β1 and γ1 laminins and greater electrostatic surface complementarity. Our findings, supported by site-directed mutagenesis, solid-phase binding analysis, laminin polymerization, and Schwann cell assays, collectively demonstrate that, in addition to inhibiting laminin polymerization, netrin-4 disassembles the pre-existing laminin lattice. The structure has the potential to facilitate the development of novel therapies for cancer treatment. Netrin-4 is a tumor suppressor that interferes with laminin lattice formation. Here, Kulczyk et al. present a cryo-EM structure of the netrin-4-laminin γ1 complex. The structure reveals how netrin-4 inhibits laminin polymerization and disassembles the laminin matrix.

The extracellular matrix (ECM) is a dynamic network of macromolecules that provides structural support for cells and orchestrates cell signaling, functions, and morphology. The basement membrane constitutes a peculiar sheet-like type of ECM located between epithelial tissues and underlying connective tissues. The major constituent of the basement membrane is laminin, which exerts a remarkable repertoire of biological functions such as cell differentiation, migration, adhesion, and wound healing. Laminin performs its functions by interacting with two main classes of receptors, the integrin and the non-integrin laminin receptors, creating a complex network essential for tissue integrity and regeneration. Dysfunctional actions of laminin are the cause of diverse human diseases, including cancer, infectious, and neurodegenerative diseases. This topic has attracted researchers for some time, but the diversity of cell-surface receptors, through which laminin signaling occurs, makes the role of laminin controversial. Moreover, different laminin isoforms were identified, and each specific tissue basement membrane differs from the others in their laminin composition. This review focuses on the structural and molecular basis and pathophysiological relevance of specific interactions between laminins and non-integrin receptors in development, health, and disease.

The carrier role of exosomes from human umbilical cord mesenchymal stem cells (hUCMSCs) containing microRNAs (miRNAs) has been implicated in gene and drug therapy. The aim of the present study was to investigate the role of exosomal microRNA-146a (miR-146a) from hUCMSCs in ovarian cancer (OC). Following the generation of docetaxel (DTX)-resistant SKOV3 cells and taxane-resistant A2780 cells, exosomes were isolated from hUCMSCs and added to the chemoresistant cells. Microarray analysis revealed that miR-146a expression was upregulated in DTX/SKOV3 cells among 15 ectopically expressed miRNAs. Analysis using the StarBase and miRSearch databases demonstrated that miR-146a targeted laminin γ2 (LAMC2), which was further verified using dual-luciferase reporter assays. Subsequently, miR-146a inhibitor or LAMC2 overexpression vectors were transfected into hUCMSCs or OC cells, respectively, and their effects on growth and chemoresistance in OC cells were assessed. The hUCMSC-derived exosomes reduced cell growth and chemoresistance in OC. Furthermore, hUCMSC-derived exosomes with miR-146a expression knocked down increased OC cell growth and chemoresistance, which was mediated by the PI3K/Akt signaling pathway via LAMC2.

Organoid technology has provided unique insights into human organ development, function, and diseases. Patient-derived organoids are increasingly used for drug screening, modeling rare disorders, designing regenerative therapies, and understanding disease pathogenesis. However, the use of Matrigel to grow organoids represents a major challenge in the clinical translation of organoid technology. Matrigel is a poorly defined mixture of extracellular matrix proteins and growth factors extracted from the Engelbreth–Holm–Swarm mouse tumor. The extracellular matrix is a major driver of multiple cellular processes and differs significantly between tissues as well as in healthy and disease states of the same tissue. Therefore, we envisioned that the extracellular matrix derived from a native healthy tissue would be able to support organoid growth akin to organogenesis in vivo. Here, we have developed hydrogels from decellularized human and bovine endometrium. These hydrogels supported the growth of mouse and human endometrial organoids, which was comparable to Matrigel. Organoids grown in endometrial hydrogels were proteomically more similar to the native tissue than those cultured in Matrigel. Proteomic and Raman microspectroscopy analyses showed that the method of decellularization affects the biochemical composition of hydrogels and, subsequently, their ability to support organoid growth. The amount of laminin in hydrogels correlated with the number and shape of organoids. We also demonstrated the utility of endometrial hydrogels in developing solid scaffolds for supporting highthroughput, cell culture–based applications. In summary, endometrial hydrogels overcome a major limitation of organoid technology and greatly expand the applicability of organoids to understand endometrial biology and associated pathologies.

Caveolin (CAV) 1 and 2 are integral membrane proteins that constitute major components of small membrane pouches termed caveolae. While several functions have been described in other tissues, the roles of CAV1 and CAV2 in the ocular surface have remained unknown. In the current study, we investigated the expression and function of CAV1 and CAV2 in the human cornea. We found CAV1 and CAV2 to be preferentially expressed by proliferative Basal Cell Adhesion Molecule (BCAM)-positive progenitor cells along the entire limbal and corneal basal epithelial layer. Functional gene knockdown studies reveal that BCAM, BCAM co-expressed Laminin α5 (LAMA5) and Laminin α3 (LAMA3) regulate expression of CAV2. Mechanistically, we demonstrate that CAV1 and CAV2 contribute to enhanced BCAM-positive cell proliferation through regulation of Fibroblast Growth Factor Receptor 2 (FGFR2) cell surface expression. In aggregate, our study identifies specific expression of CAV1 and CAV2 in BCAM-positive corneal basal epithelial cells and uncovers a novel CAV1/CAV2-dependent mechanism of corneal progenitor cell proliferation, with potential implications for therapeutic enhancement of corneal regeneration.

Laminins are heterotrimeric ECM proteins composed of α, β, and γ chains. The γ2 chain (Lm‐γ2) is a frequently expressed monomer and its expression is closely associated with cancer progression. Laminin‐γ2 contains an epidermal growth factor (EGF)‐like domain in its domain III (DIII or LEb). Matrix metalloproteinases can cleave off the DIII region of Lm‐γ2 that retains the ligand activity for EGF receptor (EGFR). Herein, we show that a novel short form of Lm‐γ2 (Lm‐γ2F) containing DIII is generated without requiring MMPs and chromosomal translocation between LAMC2 on chromosome 1 and NR6A1 gene locus on chromosome 9 in human ovarian cancer SKOV3 cells. Laminin‐γ2F is expressed as a truncated form lacking domains I and II, which are essential for its association with Lm‐α3 and ‐β3 chains of Lm‐332. Secreted Lm‐γ2F can act as an EGFR ligand activating the EGFR/AKT pathways more effectively than does the Lm‐γ2 chain, which in turn promotes proliferation, survival, and motility of ovarian cancer cells. LAMC2‐NR6A1 translocation was detected using in situ hybridization, and fusion transcripts were expressed in ovarian cancer cell tissues. Overexpression and suppression of fusion transcripts significantly increased and decreased the tumorigenic growth of cells in mouse models, respectively. To the best of our knowledge, this is the first report regarding a fusion gene of ECM showing that translocation of LAMC2 plays a crucial role in the malignant growth and progression of ovarian cancer cells and that the consequent product is a promising therapeutic target against ovarian cancers. Expression of LAMC2‐NR6A1 fusion transcripts in human ovarian carcinomas.

Pancreatic ductal adenocarcinoma (PDAC) is correlated with poor outcomes because of limited therapeutic options. Laminin-5 gamma-2 (LAMC2) plays a critical role in key biological processes. However, the detailed molecular mechanism and potential roles of LAMC2 in PDAC stay unexplored. The present study examines the essential role and molecular mechanisms of LAMC2 in the tumorigenesis of PDAC. Here, we identified that LAMC2 is significantly upregulated in microarray cohorts and TCGA RNA sequencing data of PDAC patients compared to non-cancerous/normal tissues. Patients with higher transcript levels of LAMC2 were correlated with clinical stages; dismal overall, as well as, disease-free survival. Additionally, we confirmed significant upregulation of LAMC2 in a panel of PDAC cell lines and PDAC tumor specimens in contrast to normal pancreatic tissues and cells. Inhibition of LAMC2 significantly decreased cell growth, clonogenic ability, migration and invasion of PDAC cells, and tumor growth in the PDAC xenograft model. Mechanistically, silencing of LAMC2 suppressed expression of ZEB1, SNAIL, N-cadherin (CDH2), vimentin (VIM), and induced E-cadherin (CDH1) expression leading to a reversal of mesenchymal to an epithelial phenotype. Interestingly, co-immunoprecipitation experiments demonstrated LAMC2 interaction with epidermal growth factor receptor (EGFR). Further, stable knockdown of LAMC2 inhibited phosphorylation of EGFR, ERK1/2, AKT, mTOR, and P70S6 kinase signaling cascade in PDAC cells. Altogether, our findings suggest that silencing of LAMC2 inhibited PDAC tumorigenesis and metastasis through repression of epithelial–mesenchymal transition and modulation of EGFR/ERK1/2/AKT/mTOR axis and could be a potential diagnostic, prognostic, and therapeutic target for PDAC.