Concise review: role of mesenchymal stem cells in wound repair.

Wound healing requires a coordinated interplay among cells, growth factors, and extracellular matrix proteins. Central to this process is the endogenous mesenchymal stem cell (MSC), which coordinates the repair response by recruiting other host cells and secreting growth factors and matrix proteins. MSCs are self-renewing multipotent stem cells that can differentiate into various lineages of mesenchymal origin such as bone, cartilage, tendon, and fat.

Treatment of inflammatory diseases with mesenchymal stem cells.

Human mesenchymal stem cells (hMSCs) are rare progenitor cells present in adult bone marrow that have the capacity to differentiate into a variety of tissue types, including bone, cartilage, tendon, fat, and muscle. In addition to multilineage differentiation capacity, MSCs regulate immune and inflammatory responses, providing therapeutic potential for treating diseases characterized by the presence of an inflammatory component. The availability of bone marrow and the ability to isolate and expand hMSCs ex vivo make these cells an attractive candidate for drug development.

Hypermethylation of Ron proximal promoter associates with lack of full-length Ron and transcription of oncogenic short-Ron from an internal promoter.

The gene for tyrosine-kinase receptor Ron (MST1R) resides in the chromosome 3p21.3 region, frequently affected in common human malignancies. The gene generates two transcripts, 5 and 2 kb-long, full-length Ron (flRon) and short-form Ron (sfRon), respectively.

Development and validation of ELISA for herceptin detection in human serum.

Herceptin, a humanized anti-human epidermal growth factor receptor-2 (HER2) monoclonal antibody, is used for treatment of metastatic breast cancer patients overexpressing HER2 on tumor cells, and is being studied in clinical trials for therapy of other types of cancer. In the present work, we developed a Herceptin enzyme-linked immunosorbent assay (ELISA) from commercially available reagents to meet the growing needs of clinical studies. In this immunoassay, a mixture of monoclonal antibodies specific for the cytoplasmic domain of human HER2 (676-1255 amino acids) is adsorbed onto a microtiter plate, followed by addition of full-length HER2 protein, which is captured by the antibodies.

The soluble sema domain of the RON receptor inhibits macrophage-stimulating protein-induced receptor activation.

RON is a receptor tyrosine kinase of the MET family that is involved in cell proliferation, cell survival, and cell motility in both normal and disease states. Macrophage-stimulating protein (MSP) is the RON ligand whose binding to RON causes receptor activation. RON is a trans-membrane heterodimer comprised of one alpha- and one beta-chain originating from a single-chain precursor and held together by several disulfide bonds.

Hyaluronidase 2 negatively regulates RON receptor tyrosine kinase and mediates transformation of epithelial cells by jaagsiekte sheep retrovirus.

The candidate tumor-suppressor gene hyaluronidase 2 (HYAL2) encodes a glycosylphosphatidylinositol-anchored cell-surface protein that serves as an entry receptor for jaagsiekte sheep retrovirus, a virus that causes contagious lung cancer in sheep that is morphologically similar to human bronchioloalveolar carcinoma. The viral envelope (Env) protein alone can transform cultured cells, and we hypothesized that Env could bind and sequester the HYAL2 receptor and thus liberate a potential oncogenic factor bound and negatively controlled by HYAL2. Here we show that the HYAL2 receptor protein is associated with the RON receptor tyrosine kinase (also called MST1R or Stk in the mouse), rendering it functionally silent.

Oncogenic signaling pathways activated by RON receptor tyrosine kinase.

RON (Receptuer d'Origine Nantaise) is a member of the MET receptor tyrosine kinase family. RON is expressed in various cell types including macrophages, epithelial and hematopoietic cells. Its ligand, macrophage stimulating protein (MSP, also known as hepatocyte growth factor-like protein), is a multifunctional factor regulating cell growth and survival, adhesion and motility, cytokine production and phagocytosis.

Phosphatidylinositol 3 kinase contributes to the transformation of hematopoietic cells by the D816V c-Kit mutant.

Stem cell factor (SCF) binds the receptor tyrosine kinase c-Kit and is critical for normal hematopoiesis. Substitution of valine for aspartic acid 816 (D816V) constitutively actives human c-Kit, and this mutation is found in patients with mastocytosis, leukemia, and germ cell tumors. Immortalized murine progenitor cells (MIHCs) transduced with wild-type c-Kit proliferate in response to SCF, whereas cells expressing D816V c-Kit (MIHC-D816V) are factor-independent and tumorigenic.

Oncogenic mutants of RON and MET receptor tyrosine kinases cause activation of the beta-catenin pathway.

beta-Catenin is an oncogenic protein involved in regulation of cell-cell adhesion and gene expression. Accumulation of cellular beta-catenin occurs in many types of human cancers. Four mechanisms are known to cause increases in beta-catenin: mutations of beta-catenin, adenomatous polyposis coli, or axin genes and activation of Wnt signaling.

Anti-apoptotic action of macrophage stimulating protein (MSP).

MSP is a serum protein belonging to the plasminogen-related kringle domain protein family. In addition to macrophages, epithelial cells are also MSP targets. MSP is a multifunctional factor regulating cell adhesion and motility, growth and survival.

Cross-talk between RON receptor tyrosine kinase and other transmembrane receptors.

RON is a transmembrane receptor tyrosine kinase that mediates biological activities of Macrophage Stimulating Protein (MSP). MSP is a multifunctional factor regulating cell adhesion, motility, growth and survival. MSP binding to RON causes receptor tyrosine phosphorylation leading to up-regulation of RON catalytic activity and subsequent activation of downstream signaling molecules.

Candidate tumor suppressor HYAL2 is a glycosylphosphatidylinositol (GPI)-anchored cell-surface receptor for jaagsiekte sheep retrovirus, the envelope protein of which mediates oncogenic transformation.

Jaagsiekte sheep retrovirus (JSRV) can induce rapid, multifocal lung cancer, but JSRV is a simple retrovirus having no known oncogenes. Here we show that the envelope (env) gene of JSRV has the unusual property that it can induce transformation in rat fibroblasts, and thus is likely to be responsible for oncogenesis in animals. Retrovirus entry into cells is mediated by Env interaction with particular cell-surface receptors, and we have used phenotypic screening of radiation hybrid cell lines to identify the candidate lung cancer tumor suppressor HYAL2/LUCA2 as the receptor for JSRV.

Regulation of STRA13 by the von Hippel-Lindau tumor suppressor protein, hypoxia, and the UBC9/ubiquitin proteasome degradation pathway.

In this study, we focus on different modes of regulation of STRA13, a human ortholog of the mouse basic helix-loop-helix transcriptional factor, previously identified by us as a new von Hippel-Lindau tumor suppressor gene (VHL) target. The gene was overexpressed in VHL-deficient cell lines and tumors, specifically clear cell renal carcinomas and hemangioblastomas. Introduction of wild type VHL transgene into clear cell renal carcinoma restored low level expression of STRA13.

Expression of hypoxia-inducible cell-surface transmembrane carbonic anhydrases in human cancer.

An acidic extracellular pH is a fundamental property of the malignant phenotype. In von Hippel-Lindau (VHL)-defective tumors the cell surface transmembrane carbonic anhydrase (CA) CA9 and CA12 genes are overexpressed because of the absence of pVHL. We hypothesized that these enzymes might be involved in maintaining the extracellular acidic pH in tumors, thereby providing a conducive environment for tumor growth and spread.

Gene structure of the human receptor tyrosine kinase RON and mutation analysis in lung cancer samples.

The human RON gene (MST1R) maps to 3p21.3, a region frequently altered in lung cancer and other malignancies. It encodes a receptor tyrosine kinase (RTK) closely related to MET, whose mutations are associated with neoplasia.

Integrin-mediated RON growth factor receptor phosphorylation requires tyrosine kinase activity of both the receptor and c-Src.

Cooperation between integrins and growth factor receptors plays an important role in the regulation of cell growth, differentiation, and survival. The function of growth factor receptor tyrosine kinases (RTKs) can be regulated by cell adhesion to extracellular matrix (ECM) even in the absence of ligand. We investigated the pathway involved in integrin-mediated RTK activation, using RON, the receptor for macrophage-stimulating protein.