YIGSR, a synthetic laminin pentapeptide, inhibits experimental metastasis formation

Engineering peptide-modified alginate-based bioinks with cell-adhesive properties for biofabrication

Alginate (ALG) and its oxidised form alginate-dialdehyde (ADA) are highly attractive materials for hydrogels used in 3D bioprinting as well as drop-on-demand (DoD) approaches. However, both polymers need to be modified using cell-adhesive peptide sequences, to obtain bioinks exhibiting promising cell-material interactions. Our study explores the modification of ALG- and ADA-based bioinks with the adhesive peptides YIGSR (derived from laminin), RRETEWA (derived from fibronectin) and IKVAV (derived from laminin) for 3D bioprinting. Two coupling methods, carbodiimide and Schiff base reactions, were employed to modify the polymers with peptides. Analytical techniques, including FTIR and NMR were used to assess the chemical composition, revealing challenges in confirming the presence of peptides. The modified bioinks exhibited decreased stability, viscosity, and stiffness, particularly-ADA-based bioinks in contrast to ALG. Sterile hydrogel capsules or droplets were produced using a manual manufacturing process and DoD printing. NIH/3T3 cell spreading analysis showed enhanced cell spreading in carbodiimide-modified ADA, Schiff base-modified ADA, and PEG-Mal-modified ADA. The carbodiimide coupling of peptides worked for ADA, however the same was not observed for ALG. Finally, a novel mixture of all used peptides was evaluated regarding synergistic effects on cell spreading which was found to be effective, showing higher aspect ratios compared to the single peptide coupled hydrogels in all cases. The study suggests potential applications of these modified bioinks in 3D bioprinting approaches and highlights the importance of peptide selection as well as their combination for improved cell-material interactions.

Controlling placental spheroid growth and phenotype using engineered synthetic hydrogel matrices

The human placenta is a complex organ comprised of multiple trophoblast subtypes, and inadequate models to study the human placenta in vitro limit the current understanding of human placental behavior and development. Common in vitro placental models rely on two-dimensional culture of cell lines and primary cells, which do not replicate the native tissue microenvironment, or poorly defined three-dimensional hydrogel matrices such as Matrigel™ that provide limited environmental control and suffer from high batch-to-batch variability. Here, we employ a highly defined, synthetic poly(ethylene glycol)-based hydrogel system with tunable degradability and presentation of extracellular matrix-derived adhesive ligands native to the placenta microenvironment to generate placental spheroids. We evaluate the capacity of a hydrogel library to support the viability, function, and phenotypic protein expression of three human trophoblast cell lines modeling varied trophoblast phenotypes and find that degradable synthetic hydrogels support the greatest degree of placental spheroid viability, proliferation, and function relative to standard Matrigel controls. Finally, we show that trophoblast culture conditions modulate cell functional phenotype as measured by proteomics analysis and functional secretion assays. Engineering precise control of placental spheroid development in vitro may provide an important new tool for the study of early placental behavior and development.

Assessment of bioactive peptides derived from laminin-111 as prospective breast cancer-targeting agents

Breast cancer remains a pressing public health issue primarily affecting women. Recent research has spotlighted bioactive peptides derived from laminin-111, implicated in breast tumor development. Remarkably, the sequences IKVAV, YIGSR, and KAFDITYVRLKF from the α1, β1, and γ1 chains, respectively, have garnered significant attention. This study aims to assess the potential of these radiolabeled peptides as targeting agents for breast cancer. The three peptides were synthesized using the Fmoc strategy, purified via reversed-phase high-performance liquid chromatography (RP-HPLC), and characterized through mass spectrometry. Iodine-131 (131I) radiolabeling was performed using the chloramine T method, exhibiting high radiochemical yield and stability for [131I]I-YIKVAV and [131I]I-YIGSR. Conversely, [131I]I-KAFDITYVRLKF demonstrated low radiochemical yield and stability and was excluded from the biological studies. The lipophilicity of the compounds ranged from - 2.12 to - 1.10. Serum protein binding assay for [131I]I-YIKVAV and [131I]I-YIGSR reached ≅ 48% and ≅ 25%, respectively. Affinity for breast cancer cells was evaluated using MDA-MB-231 and MCF-7 tumor cell lines, indicating the affinity of the radiopeptides with these tumor cells. Ex vivo biodistribution profiles of the radiopeptides were assessed in the MDA-MB-231 breast tumor animal model, revealing tumor tissue accumulation, supported by a high tumor-to-contralateral muscle ratio and autoradiography. These results signify the effective penetration of YIKVAV and YIGSR into tumor tissue. Therefore, the synthesized α1 and β1 peptide fragments exhibit favorable characteristics as potential breast cancer-targeting agents, promising future exploration as radiopharmaceuticals for breast cancer.

Treatment with YIGSR peptide ameliorates mouse tail lymphedema by 67 kDa laminin receptor (67LR)-dependent cell-cell adhesion

Impaired microcirculation can cause lymphatic leakage which leads to a chronic swelling in the tissues of the body. However, no successful treatment gives any protection against lymphedema due to the lack of well-revealed pathophysiology of secondary lymphedema. Binary image of laminin immunohistochemical expression revealed that distribution of laminin expression localized during surgically induced lymphedema. 67 kDa laminin receptor (67LR) mRNA expression showed a peak at during lymphedema exacerbation. Since the response of 67LR molecules may affect the prevention of inflammation and edema, here we have hypothesized that 67LR ligand of YIGSR peptide could permit reconstructive environment for amelioration of lymphedema and evaluated the effect of YIGSR in a mouse tail model of lymphedema. Indeed, intra-abdominal injections of YIGSR for the first 3 days after inducing lymphedema in the mouse tail model reduced the tail lymphedema on day 14 by 27% (P = 0.035). Histology showed that YIGSR treatment protected lymphedema impairment in epidermis and dermis, and it also inhibited the expansion of intercellular spaces and enhanced especially cell adhesion in the basement membrane as revealed by transmission electron microscopy. Interestingly, the treatment also reduced the local expression of transforming growth factor (TGF)β. Further elucidation of the mechanisms of 67LR-facilitated lymphangiogenesis contributes to find potential targets for the treatment of lymphedema.

Design of Recombinant Spider Silk Proteins for Cell Type Specific Binding

Cytophilic (cell-adhesive) materials are very important for tissue engineering and regenerative medicine. However, for engineering hierarchically organized tissue structures comprising different cell types, cell-specific attachment and guidance are decisive. In this context, materials made of recombinant spider silk proteins are promising scaffolds, since they exhibit high biocompatibility, biodegradability, and the underlying proteins can be genetically functionalized. Here, previously established spider silk variants based on the engineered Araneus diadematus fibroin 4 (eADF4(C16)) are genetically modified with cell adhesive peptide sequences from extracellular matrix proteins, including IKVAV, YIGSR, QHREDGS, and KGD. Interestingly, eADF4(C16)-KGD as one of 18 tested variants is cell-selective for C2C12 mouse myoblasts, one out of 11 tested cell lines. Co-culturing with B50 rat neuronal cells confirms the cell-specificity of eADF4(C16)-KGD material surfaces for C2C12 mouse myoblast adhesion.

The Blocking of Integrin-Mediated Interactions with Maternal Endothelial Cells Reversed the Endothelial Cell Dysfunction Induced by EVs, Derived from Preeclamptic Placentae

Placental extracellular vesicles (EVs) have increasingly been recognized as a major mediator of feto-maternal communication. However, the cellular and molecular mechanisms of the uptake of placental EVs by recipient cells are still not well-understood. We previously reported that placental EVs target a limited number of organs in vivo. In the current study, we investigated the mechanisms underlying the uptake of placental EVs into target cells. Placental EVs were derived from explant cultures of normal or preeclamptic placentae. The mechanisms underlying the uptake of placental EVs were elucidated, using the phagocytosis or endocytosis inhibitor, trypsin-treatment or integrin-blocking peptides. The endothelial cell activation was studied using the monocyte adhesion assay after the preeclamptic EVs exposure, with and/or without treatment with the integrin blocking peptide, YIGSR. The cellular mechanism of the uptake of the placental EVs was time, concentration and energy-dependent and both the phagocytosis and endocytosis were involved in this process. Additionally, proteins on the surface of the placental EVs, including integrins, were involved in the EV uptake process. Furthermore, inhibiting the uptake of preeclamptic EVs with YIGSR, reduced the endothelial cell activation. The interaction between the placental EVs and the recipient cells is mediated by integrins, and the cellular uptake is mediated by a combination of both phagocytosis and endocytosis.

Laminin Receptor-Mediated Nanoparticle Uptake by Tumor Cells: Interplay of Epigallocatechin Gallate and Magnetic Force at Nano–Bio Interface

Epigallocatechin gallate (EGCG), a major tea catechin, enhances cellular uptake of magnetic nanoparticles (MNPs), but the mechanism remains unclear. Since EGCG may interact with the 67-kDa laminin receptor (67LR) and epidermal growth factor receptor (EGFR), we investigate whether a receptor and its downstream signaling may mediate EGCG’s enhancement effects on nanoparticle uptake. As measured using a colorimetric iron assay, EGCG induced a concentration-dependent enhancement effect of MNP internalization by LN-229 glioma cells, which was synergistically enhanced by the application of a magnetic field. Transmission electron microscopy demonstrated that EGCG increased the number, but not the size, of internalized vesicles, whereas EGCG and the magnet synergistically increased the size of vesicles. EGCG appears to enhance particle–particle interaction and thus aggregation following a 5-min magnet application. An antibody against 67LR, knockdown of 67LR, and a 67LR peptide (amino acid 161–170 of 67LR) attenuated EGCG-induced MNP uptake by 35%, 100%, and 45%, respectively, suggesting a crucial role of 67LR in the effects of EGCG. Heparin, the 67LR-binding glycosaminoglycan, attenuated EGCG-induced MNP uptake in the absence, but not presence, of the magnet. Such enhancement effects of EGCG were attenuated by LY294002 (a phosphoinositide 3-kinase inhibitor) and Akt inhibitor, but not by agents affecting cGMP levels, suggesting potential involvement of signaling downstream of 67LR. In contrast, the antibody against EGFR exerted no effect on EGCG-enhanced internalization. These results suggest that 67LR may be potentially amenable to tumor-targeted therapeutics.

Enzyme-instructed self-assembly (EISA) assists the self-assembly and hydrogelation of hydrophobic peptides

Enzyme-instructed self-assembly (EISA) has several advantages in the preparation of supramolecular self-assembly materials for biomedical applications. In this study, we demonstrated that the enzyme-instructed self-assembly (EISA) strategy could assist the self-assembly and hydrogelation of two hydrophobic and bioactive peptides, tyroservatide (YSV) and laminin pentapeptide (YIGSR). We first synthesized the peptide derivatives of Nap-GFFYSV (peptide 1) and Nap-GFFYIGSR (peptide 2) and found that both peptides could not self-assemble into hydrogels due to their poor solubility. We therefore designed the phosphorylated precursors of the two hydrophobic peptides, Nap-GFFpYSV (precursor 1) and Nap-GFFpYIGSR (precursor 2), respectively, which had good solubility and can be dephosphorylated by alkaline phosphatase (ALP) to form supramolecular hydrogels. In addition, we found that the EISA could also occur on the surface of cells that overexpress ALP. The EISA strategy was a powerful method to generate hydrogels of hydrophobic compounds. We envision the big promise of the strategy in the preparation of biomaterials and nanomaterials of hydrophobic bioactive molecules.

Anti-angiogenic peptides application in cancer therapy; a review

Cancer is a disease advanced via surplus angiogenesis. The development of new anti-angiogenic therapeutic agents with more efficacy and fewer side effects is still quite necessary. Conventional therapies saving the life of many cancer patients but due to drug resistance and lack of specificity utilizing these methods is faced with limits. Recently, new therapeutic agents have been developed and used to treat cancers such as scaffold proteins, monoclonal antibodies, tyrosine kinase inhibitors, and peptides. In antiangiogenic drug development, anti-angiogenic peptides design is a significant aim. Peptides have developed as substantial therapeutics that are being carefully investigated in angiogenesis-dependent diseases because of their high penetrating rate into the cancer cells, high specificity, and low toxicity. In this review, we focus on anti-angiogenic peptides in the field of cancer therapy that are designed, screened, or derived from nanobodies, mimotopes, phage displays, and natural resources.

Chemotherapy-Induced Changes in the Lung Microenvironment: The Role of MMP-2 in Facilitating Intravascular Arrest of Breast Cancer Cells

Previously, we showed that mice treated with cyclophosphamide (CTX) 4 days before intravenous injection of breast cancer cells had more cancer cells in the lung at 3 h after cancer injection than control counterparts without CTX. At 4 days after its injection, CTX is already excreted from the mice, allowing this pre-treatment design to reveal how CTX may modify the lung environment to indirectly affect cancer cells. In this study, we tested the hypothesis that the increase in cancer cell abundance at 3 h by CTX is due to an increase in the adhesiveness of vascular wall for cancer cells. Our data from protein array analysis and inhibition approach combined with in vitro and in vivo assays support the following two-prong mechanism. (1) CTX increases vascular permeability, resulting in the exposure of the basement membrane (BM). (2) CTX increases the level of matrix metalloproteinase-2 (MMP-2) in mouse serum, which remodels the BM and is functionally important for CTX to increase cancer abundance at this early stage. The combined effect of these two processes is the increased accessibility of critical protein domains in the BM, resulting in higher vascular adhesiveness for cancer cells to adhere. The critical protein domains in the vascular microenvironment are RGD and YISGR domains, whose known binding partners on cancer cells are integrin dimers and laminin receptor, respectively.

Modeling Tissue Polarity in Context

Polarity is critical for development and tissue-specific function. However, the acquisition and maintenance of tissue polarity is context dependent. Thus, cell and tissue polarity depend on cell adhesion which is regulated by the cytoskeleton and influenced by the biochemical composition of the extracellular microenvironment and modified by biomechanical cues within the tissue. These biomechanical cues include fluid flow induced shear stresses, cell-density and confinement-mediated compression, and cellular actomyosin tension intrinsic to the tissue or induced in response to morphogens or extracellular matrix stiffness. Here, we discuss how extracellular matrix stiffness and fluid flow influence cell-cell and cell-extracellular matrix adhesion and alter cytoskeletal organization to modulate cell and tissue polarity. We describe model systems that when combined with state of the art molecular screens and high-resolution imaging can be used to investigate how force modulates cell and tissue polarity.

Peritoneal Carcinomatosis Targeting with Tumor Homing Peptides

Over recent decades multiple therapeutic approaches have been explored for improved management of peritoneally disseminated malignancies—a grim condition known as peritoneal carcinomatosis (PC). Intraperitoneal (IP) administration can be used to achieve elevated local concentration and extended half-life of the drugs in the peritoneal cavity to improve their anticancer efficacy. However, IP-administered chemotherapeutics have a short residence time in the IP space, and are not tumor selective. An increasing body of work suggests that functionalization of drugs and nanoparticles with targeting peptides increases their peritoneal retention and provides a robust and specific tumor binding and penetration that translates into improved therapeutic response. Here we review the progress in affinity targeting of intraperitoneal anticancer compounds, imaging agents and nanoparticles with tumor-homing peptides. We review classes of tumor-homing peptides relevant for PC targeting, payloads for peptide-guided precision delivery, applications for targeted compounds, and the effects of nanoformulation of drugs and imaging agents on affinity-based tumor delivery.

Enhanced gene transfection efficiency by use of peptide vectors containing laminin receptor-targeting sequence YIGSR

This study presents the design and evaluation of a series of multifunctional peptides and their gene delivery abilities. The peptide sequences contained a cell-penetrating segment, six continuous histidine residues, a stearyl moiety and a laminin receptor-targeting segment. The YIGSR segment promoted cellular uptake through the interaction with laminin receptors on the surface of cells, which resulted in a great improvement in gene transfection efficiency. The conformation, particle size and zeta potential of peptide/DNA complexes were characterized via circular dichroism and dynamic light scattering. Their gene transfection efficiency was investigated by fluorescence-activated cell sorting and confocal microscopy. The transfection efficiency of the designed peptide vectors was higher than that of Lipo 2000. The peptide TAT-H₆-K(C₁₈)-YIGSR displayed transfection efficiencies at N/P ratios of 6, which was 3.5 and 7 times higher than that of Lipo 2000 in B16F10 and 293T cells, respectively. All peptides exhibited lower cytotoxicity than Lipo 2000 in B16F10 and 293T cells. In summary, the designed YIGSR-containing multifunctional peptide gene vectors promoted cellular uptake and gene transfection. Their in vivo transfection ability was investigated in zebrafish, and the transfection efficiency was determined by confocal microscopy and bioluminescence imaging. The peptide vectors, owing to their relatively short sequences and ease of functionalization, offer a promising approach for gene delivery because of their low cytotoxicity and high transfection efficiency.

A dock derived compound against laminin receptor (37 LR) exhibits anti-cancer properties in a prostate cancer cell line model

Laminin receptor (67 LR) is a 67 kDa protein derived from a 37 kDa precursor (37 LR). 37/67 LR is a strong clinical correlate for progression, aggression, and chemotherapeutic relapse of several cancers including breast, prostate, and colon. The ability of 37/67 LR to promote cancer cell aggressiveness is further increased by its ability to transduce physiochemical and mechanosensing signals in endothelial cells and modulate angiogenesis. Recently, it was demonstrated that 37/67 LR modulates the anti-angiogenic potential of the secreted glycoprotein pigment epithelium-derived factor (PEDF). Restoration of PEDF balance is a desirable therapeutic outcome, and we sought to identify a small molecule that could recapitulate known signaling properties of PEDF but without the additional complications of peptide formulation or gene delivery safety validation. We used an in silico drug discovery approach to target the interaction interface between PEDF and 37 LR. Following cell based counter screening and binding validation, we characterized a hit compound's anti-viability, activation of PEDF signaling-related genes, anti-wound healing, and anti-cancer signaling properties. This hit compound has potential for future development as a lead compound for treating tumor growth and inhibiting angiogenesis.

Fundamentals of protein and cell interactions in biomaterials

The extracellular matrix (ECM) is an active and complex microenvironment with outstanding biomechanical, biophysical, and biochemical characteristics, which can indirectly or directly controls cell adhesion, migration, proliferation, and differentiation, as well as partaking in regeneration and homeostasis of organs and tissues. The ECM has captivated a great deal of attention with the rapid progress of tissue engineering (TE) in the field of regenerative medicine (RM). Approaches to TE, RM and cancer therapy center on the necessity to deliver cell signals to direct cell proliferation and differentiation. These "external signals" are induced from cell-cell, and cell-ECM, interactions, as well as from physico-chemical, mechanical stimuli and growth factors. With the advent of new biomaterials such as casein, we gave a general insight into cell-ECM protein interactions in biomaterials and their applications in TE, RM and cancer therapy. An account of the main ECM molecules and cellular receptors with emphasis on integrins and its ligands was given, their effect on the induction of particular signal transduction pathways is also elucidated.

Function of membranous lysyl-tRNA synthetase and its implication for tumorigenesis

Aminoacyl-tRNA synthetases (ARSs) are essential enzymes that conjugate specific amino acids to their cognate tRNAs for protein synthesis. Besides their catalytic activity, recent studies have uncovered many additional functions of these enzymes through their interactions with diverse cellular factors. Among human ARSs, cytosolic lysyl-tRNA synthetase (KRS) is often highly expressed in cancer cells and tissues, and facilitates cancer cell migration and invasion through the interaction with the 67kDa laminin receptor on the plasma membrane. Specific modulation of this interaction by small molecule inhibitors has revealed a new way to control metastasis. Here, we summarize the pro-metastatic functions of KRS and their patho-physiological implications.

Microvesicles provide a mechanism for intercellular communication by embryonic stem cells during embryo implantation

Communication between the inner cell mass (ICM) and the trophoblast layer of the blastocyst is known to occur, but its functional consequences on early developmental events is unclear. Here we demonstrate that embryonic stem (ES) cells derived from the ICM generate and shed microvesicles (MVs), a major class of extracellular vesicles (EVs), which influence trophoblast behaviour during the implantation process. The MV cargo proteins laminin and fibronectin interact with integrins along the surfaces of the trophoblasts, triggering the activation of two signalling kinases, JNK and FAK, and stimulating trophoblast migration. We further show that injecting MVs isolated from ES cells into blastocysts results in an increase in their implantation efficiency. Thus, these findings highlight a unique mechanism by which ES cells communicate with trophoblasts within the blastocyst to increase their ability to migrate into the uterus, thereby promoting one of the earliest and most important steps during pregnancy.

It is unclear how embryonic stem cells (ESC) communicate with surrounding cells during implantation. Here, the authors show that microvesicles (MV) are shed from ESCs, activating integrin and JNK/FAK kinases in trophoblasts, stimulating migration in vitro, and injecting MVs enhances blastocyst implantation.

Sequence heuristics to encode phase behaviour in intrinsically disordered protein polymers

Proteins and synthetic polymers that undergo aqueous phase transitions mediate self-assembly in nature and in man-made material systems. Yet little is known about how the phase behaviour of a protein is encoded in its amino acid sequence. Here, by synthesizing intrinsically disordered, repeat proteins to test motifs that we hypothesized would encode phase behaviour, we show that the proteins can be designed to exhibit tunable lower or upper critical solution temperature (LCST and UCST, respectively) transitions in physiological solutions. We also show that mutation of key residues at the repeat level abolishes phase behaviour or encodes an orthogonal transition. Furthermore, we provide heuristics to identify, at the proteome level, proteins that might exhibit phase behaviour and to design novel protein polymers consisting of biologically active peptide repeats that exhibit LCST or UCST transitions. These findings set the foundation for the prediction and encoding of phase behaviour at the sequence level.

Vitamins in pancreatic cancer: a review of underlying mechanisms and future applications

Although there is increasing evidence that vitamins influence pancreatic adenocarcinoma biology and carcinogenesis, a comprehensive review is lacking. In this study, we performed a PubMed literature search to review the anticancer mechanisms and the preclinical and clinical studies that support the development of the bioactive vitamins A, C, D, E, and K in pancreatic cancer intervention. Preclinical studies have shown promising results for vitamin A in pancreatic cancer prevention, with clinical trials showing intriguing responses in combination with immunotherapy. For vitamin C, preclinical studies have shown slower tumor growth rates and/or increased survival when used alone or in combination with gemcitabine, with clinical trials with this combination revealing decreased primary tumor sizes and improved performance status. Preclinical studies with vitamin D analogues have shown potent antiproliferative effects and repression of migration and invasion of pancreatic cancer cells, with a clinical trial showing increased time to progression when calciferol was added to docetaxel. For vitamin E, preclinical studies have shown that δ-tocotrienol and γ-tocotrienol inhibited tumor cell growth and survival and augmented gemcitabine activity. Early-phase clinical trials with δ-tocotrienol are ongoing. Vitamin K demonstrates activation of apoptosis and inhibition of cellular growth in pancreatic tumor cells; however, there are no clinical studies available for further evaluation. Although preclinical and clinical studies are encouraging, randomized controlled trials with endpoints based on insights gained from mechanistic and preclinical studies and early-phase clinical trials are required to determine the efficacy of bioactive vitamin interventions in pancreatic cancer.

A bioartificial environment for kidney epithelial cells based on a supramolecular polymer basement membrane mimic and an organotypical culture system

Renal applications in healthcare, such as renal replacement therapies and nephrotoxicity tests, could potentially benefit from bioartificial kidney membranes with fully differentiated and functional human tubular epithelial cells. A replacement of the natural environment of these cells is required to maintain and study cell functionality cell differentiation in vitro. Our approach was based on synthetic supramolecular biomaterials to mimic the natural basement membrane (BM) on which these cells grow and a bioreactor to provide the desired organotypical culture parameters. The BM mimics were constructed from ureidopyrimidinone (UPy)-functionalized polymer and bioactive peptides by electrospinning. The resultant membranes were shown to have a hierarchical fibrous BM-like structure consisting of self-assembled nanofibres within the electrospun microfibres. Human kidney-2 (HK-2) epithelial cells were cultured on the BM mimics under organotypical conditions in a custom-built bioreactor. The bioreactor facilitated in situ monitoring and functionality testing of the cultures. Cell viability and the integrity of the epithelial cell barrier were demonstrated inside the bioreactor by microscopy and transmembrane leakage of fluorescently labelled inulin, respectively. Furthermore, HK-2 cells maintained a polarized cell layer and showed modulation of both gene expression of membrane transporter proteins and metabolic activity of brush border enzymes when subjected to a continuous flow of culture medium inside the new bioreactor for 21 days. These results demonstrated that both the culture and study of renal epithelial cells was facilitated by the bioartificial in vitro environment that is formed by synthetic supramolecular BM mimics in our custom-built bioreactor. Copyright © 2015 John Wiley & Sons, Ltd.

Looking into laminin receptor: critical discussion regarding the non-integrin 37/67-kDa laminin receptor/RPSA protein

The 37/67-kDa laminin receptor (LAMR/RPSA) was originally identified as a 67-kDa binding protein for laminin, an extracellular matrix glycoprotein that provides cellular adhesion to the basement membrane. LAMR has evolutionary origins, however, as a 37-kDa RPS2 family ribosomal component. Expressed in all domains of life, RPS2 proteins have been shown to have remarkably diverse physiological roles that vary across species. Contributing to laminin binding, ribosome biogenesis, cytoskeletal organization, and nuclear functions, this protein governs critical cellular processes including growth, survival, migration, protein synthesis, development, and differentiation. Unsurprisingly given its purview, LAMR has been associated with metastatic cancer, neurodegenerative disease and developmental abnormalities. Functioning in a receptor capacity, this protein also confers susceptibility to bacterial and viral infection. LAMR is clearly a molecule of consequence in human disease, directly mediating pathological events that make it a prime target for therapeutic interventions. Despite decades of research, there are still a large number of open questions regarding the cellular biology of LAMR, the nature of its ability to bind laminin, the function of its intrinsically disordered C-terminal region and its conversion from 37 to 67 kDa. This review attempts to convey an in-depth description of the complexity surrounding this multifaceted protein across functional, structural and pathological aspects.

Three-layer microfibrous peripheral nerve guide conduit composed of elastin-laminin mimetic artificial protein and poly(L-lactic acid)

We developed a microfibrous poly(L-lactic acid) (PLLA) nerve conduit with a three-layered structure to simultaneously enhance nerve regeneration and prevent adhesion of surrounding tissue. The inner layer was composed of PLLA microfiber containing 25% elastin-laminin mimetic protein (AG73-(VPGIG)30) that promotes neurite outgrowth. The thickest middle layer was constructed of pure PLLA microfibers that impart the large mechanical strength to the conduit. A 10% poly(ethylene glycol) was added to the outer layer to prevent the adhesion with the surrounding tissue. The AG73-(VPGIG)30 compositing of an elastin-like repetitive sequence (VPGIG)30 and a laminin-derived sequence (RKRLQVQLSIRT: AG73) was biosynthesized using Escherichia coli. The PLLA microfibrous conduits were fabricated using an electrospinning procedure. AG73-(VPGIG)30 was successfully mixed in the PLLA microfibers, and the PLLA/AG73-(VPGIG)30 microfibers were stable under physiological conditions. The PLLA/AG73-(VPGIG)30 microfibers enhanced adhesion and neurite outgrowth of PC12 cells. The electrospun microfibrous conduit with a three-layered structure was implanted for bridging a 2.0-cm gap in the tibial nerve of a rabbit. Two months after implantation, no adhesion of surrounding tissue was observed, and the action potential was slightly improved in the nerve conduit with the PLLA/AG73-(VPGIG)30 inner layer.

Recombinant silk fibroin incorporated cell-adhesive sequences produced by transgenic silkworm as a possible candidate for use in vascular graft

Transgenic silk fibroins that incorporated the laminin sequence were prepared. The adhesive activities tend to increase in the TG silk fibroins relative to WT silk fibroins.

Laminin drives survival signals to promote a contractile smooth muscle phenotype and airway hyperreactivity

Increased airway smooth muscle (ASM) mass is believed to underlie the relatively fixed airway hyperresponsiveness (AHR) in asthma. Developments of therapeutic approaches to reverse airway remodeling are impeded by our lack of insight on the mechanisms behind the increase in mass of contractile ASM cells. Increased expression of laminin, an extracellular matrix protein, is associated with asthma. Our studies investigate the role of laminin-induced ASM survival signals in the development of increased ASM and AHR. Antagonizing laminin integrin binding using the laminin-selective competing peptide, YIGSR, and mimicking laminin with exogenous α2-chain laminin, we show that laminin is both necessary and sufficient to induce ASM cell survival, concomitant with the induction of ASM contractile phenotype. Using siRNA, we show that the laminin-binding integrin α7β1 mediates this process. Moreover, in laminin-211-deficient mice, allergen-induced AHR was not observed. Notably, ASM cells from asthmatic airways express a higher abundance of intracellular cell survival proteins, consistent with a role for reduced rates of cell apoptosis in development of ASM hyperplasia. Targeting the laminin-integrin α7β1 signaling pathway may offer new avenues for the development of therapies to reduce the increase in mass of contractile phenotype ASM cells that underlie AHR in asthma.

Engineering the regenerative microenvironment with biomaterials

Modern synthetic biomaterials are being designed to integrate bioactive ligands within hydrogel scaffolds for cells to respond and assimilate within the matrix. These advanced biomaterials are only beginning to be used to simulate the complex spatio-temporal control of the natural healing microenvironment. With increasing understanding of the role of growth factors and cytokines and their interactions with components of the extracellular matrix, novel biomaterials are being developed that more closely mimic the natural healing environments of tissues, resulting in increased efficacy in applications of tissue repair and regeneration. Herein, the important aspects of the healing microenvironment, and how these features can be incorporated within innovative hydrogel scaffolds, are presented.

Laminin-111-derived peptides and cancer

Laminin-111 is a large trimeric basement membrane glycoprotein with many active sites. In particular, four peptides active in tumor malignancy studies have been identified in laminin-111 using a systematic peptide screening method followed by various assays. Two of the peptides (IKVAV and AG73) are found on the α1 chain, one (YIGSR) of the β1 chain and one (C16) on the γ1 chain. The four peptides have distinct activities and receptors. Since three of the peptides (IKVAV, AG73 and C16) strongly promote tumor growth, this may explain the potent effects laminin-111 has on malignant cells. The peptide, YIGSR, decreases tumor growth and experimental metastasis via a 32/67 kD receptor while IKVAV increases tumor growth, angiogenesis and protease activity via integrin receptors. AG73 increases tumor growth and metastases via syndecan receptors. C16 increases tumor growth and angiogenesis via integrins. Identification of such sites on laminin-111 will have use in defining strategies to develop therapeutics for cancer.

Synergetic downregulation of 67 kDa laminin receptor by the green tea (Camellia sinensis) secondary plant compound epigallocatechin gallate: a new gateway in metastasis prevention?

BACKGROUND

In traditional Chinese medicine, green tea is considered to have a life-prolonging effect, possibly as a result of its rich content of antioxidant tea polyphenols, and hence has the potential to prevent cancer. This study investigated the role of the major tea secondary plant compound epigallocatechin gallate (EGCG) for its inhibitory effects on the metastasis-associated 67 kDa laminin receptor (67LR).

METHODS

To clarify the impact of EGCG on siRNA-silenced expression of 67LR, we applied an adenoviral-based intestinal in vitro knockdown model, porcine IPEC-J2 cells. Quantitative real-time polymerase chain reaction was performed to analyze 67LR gene expression following treatment with physiological and pharmacological concentrations of EGCG (1.0 g/l, 0.1 g/l, 0.02 g/l and 0.002 g/l).

RESULTS

We report co-regulation of EGCG and 67LR, which is known to be an EGCG receptor. siRNA selectively and highly significantly suppressed expression of 67LR under the impact of EGCG in a synergetic manner.

CONCLUSIONS

Our findings suggest that 67LR expression is regulated by EGCG via a negative feedback loop. The explicit occurrence of this effect in synergy with a small RNA pathway and a plant-derived drug reveals a new mode of action. Our findings may help to provide insights into the many unsolved health-promoting activities of other natural pharmaceuticals.

Global methylation profiling in serous ovarian cancer is indicative for distinct aberrant DNA methylation signatures associated with tumor aggressiveness and disease progression

OBJECTIVE

To characterize at high resolution the DNA methylation changes which occur in the genome of serous epithelial ovarian cancer (EOC) in association with tumor aggressiveness.

METHODS

Methylated DNA immunoprecipitation in combination with CpG island-tiling arrays was used to compare the methylation profiles of five borderline, five grade 1/stage III/IV, five grade 3/stage I and five grade 3/stage III/IV serous EOC tumors, to those of five normal human ovarian tissue samples.

RESULTS

We found widespread DNA hypermethylation that occurs even in low-malignant potential (borderline) tumors and which predominantly includes key developmental/homeobox genes. Contrary to DNA hypermethylation, significant DNA hypomethylation was observed only in grade 3 serous EOC tumors. The latter observation was further confirmed when comparing the DNA methylation profiles of primary cell cultures derived from matched tumor samples obtained prior to, and following chemotherapy treatment from two serous EOC patients with advanced disease. To our knowledge this is the first report that has shown the presence of massive DNA hypomethylation in advanced serous EOC, associated with tumor malignancy and disease progression.

CONCLUSIONS

Our data raise the concern that demethylating drugs that are currently being used in advanced EOC disease (representing the majority of serous EOC cases) might have adverse effects due to activation of oncogenes and prometastatic genes. Understanding the relative roles of hypomethylation and hypermethylation in cancer could have clear implications on the therapeutic use of agents targeting the DNA methylation machinery.

Laminin-511: a multi-functional adhesion protein regulating cell migration, tumor invasion and metastasis

Laminins are major constituents of basement membranes. At least 16 isoforms have now been described, each with distinct spatio-temporal expression patterns and functions. The laminin-511 heterotrimer (α5β1γ1) is one of the more recent isoforms to be identified and a potent adhesive and pro-migratory substrate for a variety of normal and tumor cell lines in vitro. As our understanding of its precise function in normal tissues and in pathologies is rapidly unraveling, current evidence suggests an important regulatory role in cancer. This review describes published data on laminin-511 expression in several malignancies and experimental evidence from both in vitro and in vivo studies supporting its functional role during tumor progression. A particular emphasis is put on more recent studies from our laboratory and that of others indicating that laminin-511 contributes to tumor dissemination and metastasis in advanced breast carcinomas and other tumor types. Collectively, the experimental evidence suggests that high expression of laminin-511 has prognostic significance and that targeting tumor-laminin-511 interactions may have therapeutic potential in advanced cancer patients.

Comprehensive proteomic analysis of nonintegrin laminin receptor interacting proteins

Human nonintegrin laminin receptor is a multifunctional protein acting as an integral component of the ribosome and a cell surface receptor for laminin-1. The laminin receptor is overexpressed in several human cancers and is also the cell surface receptor for several viruses and pathogenic prion proteins, making it a pathologically significant protein. This study focused on the proteomic characterization of laminin receptor interacting proteins from Mus musculus. The use of affinity chromatography with immobilized recombinant laminin receptor coupled with mass spectrometry analysis identified 45 proteins with high confidence. Following validation through coimmunoprecipitation, the proteins were classified based on predicted function into ribosomal, RNA processing, signal transduction/metabolism, protein processing, cytoskeleton/cell anchorage, DNA/chromatin, and unknown functions. A significant portion of the identified proteins is related to functions or localizations previously described for laminin receptor. This work represents a comprehensive proteomic approach to studying laminin receptor and provides an essential stepping stone to a better mechanistic understanding of this protein's diverse functions.

Microfluidic generation of haptotactic gradients through 3D collagen gels for enhanced neurite growth

We adapted a microfluidic system used previously to generate durotactic gradients of stiffness in a 3D collagen gel, to produce haptotactic gradients of adhesive ligands through the collagen gel. Oligopeptide sequences that included bioactive peptide sequences from laminin, YIGSR, or IKVAV, were grafted separately onto type I collagen using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). Solutions of peptide-grafted collagen and untreated collagen were then used as source and sink input solutions, respectively, in an H-shaped microfluidic network fabricated using traditional soft lithography. One-dimensional gradients of the peptide-grafted collagen solution were generated in the channel that connected the source and sink channels, and these gradients became immobilized upon self-assembly of the collagen into a 3D fibrillar gel. The slope and average concentration of the gradients were adjusted by changing the concentration of the source solutions and by changing the length of the cross-channel. A separate, underlying channel in the microfluidic construct allowed the introduction of a chick embryo dorsal root ganglion into the network. Neurites from these explants grew significantly longer up steep gradients of YIGSR, but shallow gradients of IKVAV in comparison to untreated collagen controls. When these two gradients were presented in combination, the bias in growth acceleration was the largest and most consistent. No differences were observed in the number of neurites choosing to grow up or down the gradients in any condition. These results suggest that the incorporation of distinct gradients of multiple bioactive ligands can improve directional acceleration of regenerating axons.

Targeting integrins in hepatocellular carcinoma

INTRODUCTION

Integrins, which are heterodimeric membrane glycoproteins, consist of a family of cell-surface receptors mediating cell-matrix and cell-cell adhesion. Analysis of tumor-associated integrins has revealed an important relationship between integrins and tumor development, bringing new insights into integrin-based cancer therapies. Hepatocellular carcinoma (HCC) is one of the most malignant tumors worldwide and integrins appeal to be a novel group of potential therapeutic targets for HCC.

AREAS COVERED

This review summarizes the current knowledge of integrins involved in HCC and the potential of integrin-targeted drugs in HCC therapy. A brief introduction on the structure, biological function and regulatory mechanism of integrins is given. The distinct expression patterns and biological functions of HCC-associated integrins are described. Finally, the current situation of integrin-based therapies in HCC and other tumor types are extensively discussed in the light of their implications in preclinical and clinical trials.

EXPERT OPINION

To date, increasing numbers of integrin-targeted drugs are undergoing development and they exhibit diverse effects in cancer clinical trials. Tumor heterogeneity should be emphasized in developing effective integrin-targeted drugs specific for HCC. A better understanding of how integrins cooperatively function in HCC will assist in designing more successful integrin-targeted therapeutic drugs and corresponding approaches.

Multifactorial optimization of endothelial cell growth using modular synthetic extracellular matrices

Extracellular matrices (ECMs) are complex materials, containing at least dozens of different macromolecules that are assembled together, thus complicating their optimization towards applications in 3D cell culture or tissue engineering. The natural complexity of ECMs has limited cell-matrix investigations predominantly to experiments where only one matrix component is adjusted at a time, making it difficult to uncover interactions between different matrix components or to efficiently determine optimal matrix compositions for specific desired biological responses. Here we have developed modular synthetic ECMs based on peptide self-assembly whose incorporation of multiple different peptide ligands can be adjusted. The peptides can co-assemble in a wide range of combinations to form hydrogels of uniform morphology and consistent mechanical properties, but with precisely varied mixtures of peptide ligands. The modularity of this system in turn enabled multi-factorial experimental designs for investigating interactions between these ligands and for determining a multi-peptide matrix formulation that maximized endothelial cell growth. In cultures of HUVECs, we observed a previously unknown antagonistic interaction between the laminin-derived peptide YIGSR and RGDS-mediated cell attachment and growth. We also identified an optimized combination of self-assembled peptides bearing the ligands RGDS and IKVAV that led to endothelial cell growth equivalent to that on native full-length fibronectin. Both of these findings would have been challenging to uncover using more traditional one-factor-at-a-time analyses.

Regulation of valvular interstitial cell calcification by adhesive peptide sequences

Knowledge of how valvular interstitial cells (VICs) interact with the extracellular matrix (ECM) would aid in not only better understanding the etiology of valvular disease but also constructing appropriate environments for valve tissue engineering. In this work, the calcification of VICs cultured on ECM coatings (fibronectin, fibrin, collagen, and laminin) or ECM-derived peptide sequences (RGDS, YIGSR, and DGEA) was quantified via several techniques. Neutralizing antibodies to specific adhesion receptors were also applied, followed by quantification of phenotypic markers related to valve calcification. The calcification of VICs varied with the ECM component or peptide that was presented on the culture substrate. VICs calcified the most on RGDS and least on YIGSR and DGEA, while blocking specific receptors revealed that disruption of VIC binding via the alpha(5)beta(1) integrin or the 67-kDa laminin receptor had a dramatic calcification-stimulating effect. Binding via the alpha(2)beta(1) integrin did not alter calcification or VIC phenotype. These findings were translated to 3D peptide-modified scaffold environments that demonstrated varying levels of disease expression by VICs. Thus, specific adhesion receptors play a significant role in mediating the interactions between VICs and ECM that lead to calcification, which provides important information regarding the mechanisms of valvular disease and scaffold design for valve tissue engineering.

High expression of 67-kDa laminin receptor relates to the proliferation of leukemia cells and increases expression of GM-CSF receptor

OBJECTIVE

The 67-kDa laminin receptor (LR) is a nonintegrin receptor for laminin, a major component of the extracellular matrix. To elucidate the role of LR in leukemia cells, we studied the relationship between the phenotype of leukemia cells and LR expression.

MATERIALS AND METHODS

The relationship between clinical features of acute myeloid leukemia and expression of LR was examined. LR was overexpressed or suppressed by the introduction of complementary DNA or small interfering RNA for LR in a human leukemia cell line to test the effect of LR on the phenotype of leukemia. Expression of granulocyte-macrophage colony-stimulating factor receptors (GM-CSFR) was also tested in leukemia cells, including clinical samples.

RESULTS

Expression of LR was significantly related to elevation of white blood cell count, lactate dehydrogenase, and survival among acute myeloid leukemia patients. Forced expression of LR enhanced proliferation, cell-cycle progression, and antiapoptosis of leukemia cells associated with phosphorylation of a transcription factor, signal transducer and activator of transcription 5, in the absence of stimulation by laminin. On the other hand, suppression of LR expression had the opposite effects. The number of GM-CSFR increased in leukemia cells overexpressing LR, and there was a significant relationship between the expression of LR and GM-CSFR in acute myeloid leukemia samples.

CONCLUSIONS

These results suggest that LR expression influenced the characteristics of leukemia cells toward an aggressive phenotype and increased the number of GM-CSFR. These changes might be partly related to enhanced GM-CSF signaling.

Mining the extracellular matrix for tissue engineering applications

Tissue engineering is a rapidly evolving interdisciplinary field that aims to regenerate new tissue to replace damaged tissues or organs. The extracellular matrix (ECM) of animal tissues is a complex mixture of macromolecules that play an essential instructional role in the development of tissues and organs. Therefore, tissue engineering approaches rely on the need to present the correct cues to cells, to guide them to maintain tissue-specific functions. Recent research efforts have allowed us to mine various sequences and motifs, which play key roles in these guidance functions, from the ECM. Small conserved peptide sequences mined from ECM molecules can mimic some of the biological functions of their large parent molecules. In addition, these peptide sequences can be linked to various biomaterial scaffolds that can provide the cells with mechanical support to ensure appropriate cell growth and aid the formation of the correct tissue structure. The tissue engineering field will continue to benefit from the advent of these mined ECM sequences which have two major advantages over recombinant ECM molecules: material consistency and scalability.