Noninvasive imaging of c(RGD)2‐9R as a potential delivery carrier for transfection of siRNA in malignant tumors

The purpose of our study was to develop and evaluate a novel integrin α_vβ₃‐specific delivery carrier for transfection of siRNA in malignant tumors. We adopted arginine‐glycine‐aspartate (RGD) motif as a tissue target for specific recognition of integrin α_νβ₃. A chimaeric peptide was synthesized by adding nonamer arginine residues (9‐arginine [9R]) at the carboxy terminus of cyclic‐RGD dimer, designated as c(RGD)₂‐9R, to enable small interfering RNA (siRNA) binding. To test the applicability of the delivery carrier in vivo, c(RGD)₂‐9R was labeled with radionuclide of technetium‐99m. Biodistribution and γ‐camera imaging studies were performed in HepG2 xenograft‐bearing nude mice. As results, an optimal 10:1 molar ratio of ^99mTc‐c(RGD)₂‐9R to siRNA was indicated by the electrophoresis on agarose gels. ^99mTc‐c(RGD)₂‐9R/siRNA remained stable under a set of conditions in vitro. For in vivo study, tumor radioactivity uptake of ^99mTc‐c(RGD)₂‐9R/siRNA in nude mice bearing HepG2 xenografts was significantly higher than that of control probe (P  < .05). The xenografts were clearly visualized at 4 hours till 6 hours noninvasively after intravenous injection of ^99mTc‐c(RGD)₂‐9R/siRNA, while the xenografts were not visualized at any time after injection of control probe. It was concluded that c(RGD)₂‐9R could be an effective siRNA delivery carrier. Technetium‐99m radiolabeled‐delivery carrier represents a potential imaging strategy for RNAi‐based therapy.     

Integrin α9 depletion promotes β-catenin degradation to suppress triple-negative breast cancer tumor growth and metastasis

Although integrin α9 (ITGA9) is known to be involved in cell adhesion and motility, its expression in cancer and its role in tumor growth and metastasis remain largely unknown. Our study was designed to investigate the role of ITGA9 in triple-negative breast cancer (TNBC). ITGA9 expression in TNBC cells was knocked out (KO) using CRISPR/Cas9 technology. Four orthotopic mouse mammary xenograft tumor models coupled with cell culture studies were performed to determine the effect of ITGA9 depletion on TNBC tumor growth and metastasis and the underlying mechanism. Bioinformatics analysis showed that ITGA9 level is significantly higher in TNBC than other breast cancer subtypes, and higher ITGA9 level is associated with significantly worse distant metastasis-free survival and recurrence-free survival in TNBC patients. Experimentally, ITGA9 KO significantly reduced TNBC cell cancer stem cell (CSC)-like property, tumor angiogenesis, tumor growth and metastasis by promoting β-catenin degradation. Further mechanistic studies revealed that ITGA9 KO causes integrin-linked kinase (ILK) relocation from the membrane region to the cytoplasm, where it interacts with protein kinase A (PKA) and inhibits PKA activity leading to increased activity of glycogen synthase kinase 3 (GSK3) and subsequent β-catenin degradation. Overexpressing β-catenin in ITGA9 KO cells reversed the inhibitory effect of ITGA9 KO on tumor growth and metastasis. Furthermore, ITGA9 downregulation in TNBC tumors by nanoparticle-mediated delivery of ITGA9 siRNA drastically decreased tumor angiogenesis, tumor growth and metastasis. These findings indicate that ITGA9 depletion suppresses TNBC tumor growth and metastasis by promoting β-catenin degradation through the ILK/PKA/GSK3 pathway.     

子宫内膜容受性相关标志物的研究进展

人类生殖过程中女性能否成功妊娠的两个重要因素包括胚胎质量和子宫内膜的容受性，其中胚胎质量原因占1／3，而子宫内膜的容受性原因占2／3。不孕与多种因素有关，近年来关于子宫内膜容受性导致的不孕已成为国内外生殖医学界争相研究的热点。该文主要从子宫内膜分子生物学方面综述影响子宫内膜容受性相关因素的最新研究进展。     

Use of GPIIb/IIIa inhibitors in cardiovascular medicine

The GPIIb/IIIa inhibitors were the first clinically used anti-integrin therapeutics. They opened the gate to a rapidly developing area of anti-integrin targeting as a therapeutic approach to many diseases. The use of GPIIb/IIIa inhibitors in interventional cardiology is widespread and still increasing, as is the number of percutaneous coronary interventions. There seems to be a class effect of GPIIb/IIIa inhibitors in percutaneous coronary intervention, but there are major differences in the pharmacokinetics and pharmacodynamics of these agents. Currently clinically approved for parenteral use are the Fab fragment abciximab (ReoPro^®, Lilly) and the small-molecule GPIIb/IIIa inhibitors eptifibatide (Integrilin^®, Millennium/Schering-Plough) and tirofiban (Aggrastat^®, Merck). This review focuses on the different pharmacological properties of these agents and summarizes present and future therapeutic use of GPIIb/IIIa inhibitors in cardiovascular and other vascular diseases.     

The urokinase-type plasminogen activator (uPA) system as a biomarker and therapeutic target in human malignancies

Introduction: The urokinase plasminogen activator (uPA) system, comprising the serine protease uPA, its cognate receptor, uPAR, and two endogenous inhibitors, plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2), is a key player in the break-down of extracellular matrix (ECM) and basement membrane. Elevated expression of uPA and uPAR is observed in numerous cancer types and associated with poor prognosis.

Areas covered: In addition to the aberrant expression during tumor development, the components of uPA system are functionally involved in various processes that are prerequisite for cancer progression. These processes include, but not limited to, ECM degradation, angiogenesis, cell proliferation, adhesion, migration and epithelial–mesenchymal transition. All of these findings implicate uPA system as a target for cancer treatment. Thus, therapeutic agents and approaches to targeting the constituents of uPA system, mainly at their expression level and biological activities, have been extensively used in antineoplastic investigations.

Expert opinion: Because of promising results obtained from previous preclinical studies, several clinical trials aimed at inhibiting the expression or function of uPA/uPAR have been completed or are ongoing. In these trials, favorable outcomes in reducing metastatic spread and extending the lifespan of cancer patients have been reported, and no severe adverse events were observed.     

Increased circulating anti‐α6‐integrin autoantibodies in psoriasis and psoriatic arthritis but not in rheumatoid arthritis

In psoriatic skin, laminin integrity is altered, which could lead to insufficient laminin integrin interactions, leaving the α6‐integrin exposed and possibly accessible for autoantibody production. Therefore we investigated the presence of anti‐α6‐integrin autoantibodies in the serum of patients with psoriasis vulgaris (Ps), psoriatic arthritis (PsA) and rheumatoid arthritis (RA) in comparison with healthy donors. The level of circulating anti‐α6‐integrin antibodies was determined by enzyme‐linked immunoassay using α6‐integrin fragments. Antibodies against at least one recombinant fragment were found in approximately 30% of Ps and PsA patients. In contrast, in RA patients, the frequency of antibodies was similar to healthy controls. Our study shows the presence of anti‐α6‐integrin antibodies in Ps and PsA but not in RA, which could indicate ongoing abnormal processes in the skin. Anti‐α6‐integrin autoantibodies may contribute to the formation of micro‐wounds in the skin and to the characteristic wound‐healing phenotype in psoriasis.     

Expression of CD151/Tspan24 and integrin alpha 3 complex in aid of prognostication of HER2-negative high-grade ductal carcinoma in situ

The pro-tumorigenic and pro-metastatic functions of the tetraspanin protein CD151 (Tspan24) are thought to be dependent on its ability to form complexes with laminin-binding integrin receptors (i.e. alpha6beta1, alpha3beta1, alpha6beta4). We have previously reported that in invasive ductal carcinoma (IDC), CD151/alpha3beta1 complex was of prognostic value in patients with HER2-negative tumors. Extrapolating these findings to the pre-invasive setting, we aimed to make an assessment of a potential relationship between expression of the CD151/alpha3beta1 complex in DCIS and Van Nuys prognostic index (VNPI) in high-grade ductal carcinoma in situ (DCIS) in relation to the HER2 status. Protein distributions were analyzed in 49 samples of pure DCIS using immunohistochemistry. For each case immunoreactivity was assessed in at least 5 ducts (325 ducts in total) and an average score was taken for statistical analyses. When analyzed in the whole cohort, there was no statistical association between the VNPI and any of the proteins scored either separately or in combination. When stratified according to the HER2 status, in the HER2-negative subgroup, CD151 assessed in combination with alpha3beta1 was significantly correlated with VNPI (P = 0.044), while neither protein analyzed individually showed any significant link with the prognostic index. Expression of the CD151/alpha3beta1 complex in HER2-negative DCIS might reflect tumor behavior relevant to the patient outcome and thus might aid prognostication of the disease.     

Matrix stiffness regulation of integrin‐mediated mechanotransduction during osteogenic differentiation of human mesenchymal stem cells

Mesenchymal stem cells (MSCs) cultured on extracellular matrices with different stiffness have been shown to possess diverse lineage commitment owing to the extracellular mechanical stimuli sensed by the cells. The aim of this study was to further delineate how matrix stiffness affects intracellular signaling through the mechanotransducers Rho kinase (ROCK) and focal adhesion kinase (FAK) and subsequently regulates the osteogenic phenotype of MSCs. MSCs were cultured in osteogenic medium on tunable polyacrylamide hydrogels coated with type I collagen with elasticities corresponding to Young's modulus of 7.0 ± 1.2 and 42.1 ± 3.2 kPa. Osteogenic differentiation was increased on stiffer matrices, as evident by type I collagen, osteocalcin, and Runx2 gene expressions and alizarin red S staining for mineralization. Western blot analysis demonstrated an increase in kinase activities of ROCK, FAK, and ERK1/2 on stiffer matrices. Inhibition of FAK, an important mediator of osteogenic differentiation, and inhibition of ROCK, a known mechanotransducer of matrix stiffness during osteogenesis, resulted in decreased expression of osteogenic markers during osteogenic induction. In addition, FAK affects osteogenic differentiation through ERK1/2, whereas ROCK regulates both FAK and ERK1/2. Furthermore, α₂‐integrin was upregulated on stiffer matrices during osteogenic induction, and its knockdown by siRNA downregulated the osteogenic phenotype through ROCK, FAK, and ERK1/2. Taken together, our results provide evidence that the matrix rigidity affects the osteogenic outcome of MSCs through mechanotransduction events that are mediated by α₂‐integrin. © 2011 American Society for Bone and Mineral Research.     

整合素及其在眼科疾病中的作用

整合素是由细胞分泌,存在于细胞表面的一种跨膜蛋白.其主要功能是参与细胞与细胞、细胞与细胞外基质的黏附和信号转导.在晶状体的发育与晶状体疾病、青光眼、角膜病、近视、增生性玻璃体视网膜病变中,整合素参与细胞的识别、活化和信号转导,参与细胞的增生、分化以及细胞的伸展和迁移,从而改变了细胞与细胞外基质的微环境,引起一系列生理病理变化.