TGFB1-driven mesenchymal stem cell-mediated NIS gene transfer.

Based on their excellent tumor-homing capacity, genetically engineered mesenchymal stem cells (MSCs) are under investigation as tumor-selective gene delivery vehicles. Transgenic expression of the sodium iodide symporter (NIS) in genetically engineered MSCs allows noninvasive tracking of MSC homing by imaging of functional NIS expression as well as therapeutic application of 131I. The use of tumor stroma-activated promoters can improve tumor-specific MSC-mediated transgene delivery. The essential role of transforming growth factor B1 (TGFB1) and the SMAD downstream target in the signaling between tumor and the surrounding stroma makes the biology of this pathway a potential option to better control NIS expression within the tumor milieu. Bone marrow-derived MSCs were stably transfected with a NIS-expressing plasmid driven by a synthetic SMAD-responsive promoter (SMAD-NIS-MSCs). Radioiodide uptake assays revealed a 4.9-fold increase in NIS-mediated perchlorate-sensitive iodide uptake in SMAD-NIS-MSCs after TGFB1 stimulation compared to unstimulated cells demonstrating the successful establishment of MSCs, which induce NIS expression in response to activation of TGFB1 signaling using a SMAD-responsive promoter. 123I-scintigraphy revealed significant tumor-specific radioiodide accumulation and thus NIS expression after systemic application of SMAD-NIS-MSCs into mice harboring subcutaneous tumors derived from the human hepatocellular carcinoma (HCC) cell line HuH7, which express TGFB1. 131I therapy in SMAD-NIS-MSCs-treated mice demonstrated a significant delay in tumor growth and prolonged survival. Making use of the tumoral TGFB1 signaling network in the context of MSC-mediated NIS gene delivery is a promising approach to foster tumor stroma-selectivity of NIS transgene expression and tailor NIS-based gene therapy to TGFB1-rich tumor environments.

Lymphotoxin expression in human and murine renal allografts.

The kidney is the most frequently transplanted solid organ. Recruitment of inflammatory cells, ranging from diffuse to nodular accumulations with defined microarchitecture, is a hallmark of acute and chronic renal allograft injury. Lymphotoxins (LTs) mediate the communication of lymphocytes and stromal cells and play a pivotal role in chronic inflammation and formation of lymphoid tissue. The aim of this study was to assess the expression of members of the LT system in acute rejection (AR) and chronic renal allograft injury such as transplant glomerulopathy (TG) and interstitial fibrosis/tubular atrophy (IFTA). We investigated differentially regulated components in transcriptomes of human renal allograft biopsies. By microarray analysis, we found the upregulation of LTß, LIGHT, HVEM and TNF receptors 1 and 2 in AR and IFTA in human renal allograft biopsies. In addition, there was clear evidence for the activation of the NFκB pathway, most likely a consequence of LTß receptor stimulation. In human renal allograft biopsies with transplant glomerulopathy (TG) two distinct transcriptional patterns of LT activation were revealed. By quantitative RT-PCR robust upregulation of LTα, LTß and LIGHT was shown in biopsies with borderline lesions and AR. Immunohistochemistry revealed expression of LTß in tubular epithelial cells and inflammatory infiltrates in transplant biopsies with AR and IFTA. Finally, activation of LT signaling was reproduced in a murine model of renal transplantation with AR. In summary, our results indicate a potential role of the LT system in acute renal allograft rejection and chronic transplant injury. Activation of the LT system in allograft rejection in rodents indicates a species independent mechanism. The functional role of the LT system in acute renal allograft rejection and chronic injury remains to be determined.

Cell surface engineering of renal cell carcinoma with glycosylphosphatidylinositol-anchored TIMP-1 blocks TGF- ß 1 activation and reduces regulatory ID gene expression.

Tissue inhibitor of metalloproteinase 1 (TIMP-1) controls matrix metalloproteinase activity through 1:1stoichiometric binding. Human TIMP-1 fused to a glycosylphosphatidylinositol(GPI) anchor (TIMP-1 - GPI) shifts the activity of TIMP-1 from the extracellular matrix to the cell surface. TIMP-1 - GPI treated renal cell carcinoma cells show increased apoptosis and reduced proliferation.Transcriptomic profiling and regulatory pathway mapping were used to identify the potential mechanisms driving these effects. Significant changes in the DNA binding inhibitors, TGF- ß 1/SMAD and BMP pathways resulted from TIMP-1 - GPI treatment. These events were linked to reduced TGF- ß 1 signaling mediated by inhibition of proteolytic processing of latent TGF- ß 1 by TIMP-1 - GPI.