Cancer stem cells (CSCs) are a small subset of cancer cells responsible for maintenance and progression of several types of cancer. Isolation, propagation, and the differentiation of CSCs in the proper stem niches expose the intrinsic difficulties for further studies. Here we show that induced cancer like stem cells (iCLSCs) can be generated by in vitro oncogenic manipulation of mouse embryonic stem cells (mESCs) with well-defined oncogenic elements; SV40 LTg and HrasV12 by using a mouse stem virus long terminal repeat (MSCV-LTR)-based retroviral system. The reprogrammed mESCs using both oncogenes were characterized through their oncogenic gene expression, the enhancement of proliferation, and unhampered maintenance of stem properties in vitro and in vivo. In addition, these transformed cells resulted in the formation of malignant, immature ovarian teratomas in vivo. To successfully further expand these properties to other organs and species, more research needs to be done to fully understand the role of a tumor- favorable microenvironment. Our current study has provided a novel approach to generate induced cancer like stem cells through in vitro oncogenic reprogramming and successfully initiated organ-specific malignant tumor formation in an orthotopic small animal cancer model.

It is becoming increasingly clear that T cell responses against many antigens are dominated by public α/β T cell receptors (TCRs) with restricted heterogeneity. Because expression of public TCRs may be related to resistance, or predisposition to diseases, it is relevant to measure their frequencies. Although staining with tetrameric peptide/major histocompatibility complex (pMHC) molecules gives information about specificity, it does not give information about the TCR composition of the individual T cells that stain. Moreover, next-generation sequencing of TCR does not yield information on pairing of α- and β-chains in single T cells. In an effort to overcome these limitations, we have here investigated the possibility of raising a monoclonal antibody (moAb) that recognizes a public TCR. As a model system, we have used T cells responding to the 91-101 CDR3 peptide of an Ig L-chain (λ2³¹⁵), presented by the MHC class II molecule I-E(d). The CD4⁺ T cell responses against this pMHC are dominated by a receptor composed of Vα3Jα1;Vβ6DβJβ1.1. Even the V(D)J junctions are to a large extent shared between T cell clones derived from different BALB/c mice. We here describe a murine moAb (AB10) of B10.D2 origin that recognizes this public TCR, while binding to peripheral T cells is negligible. Binding of the moAb is abrogated by introduction of two Gly residues in the D-J junction of the CDR3 of the β-chain. A model for the public TCR determinant is presented.
© 2013 John Wiley & Sons Ltd.

IL-7 is a major regulator of lymphocyte homeostasis; however, little is known about the mechanisms that regulate IL-7 production. To study Il7 gene regulation in vivo, we generated a novel IL-7-reporter mouse, which allows the non-invasive quantification of Il7 gene activity in live mice and, additionally, the simultaneous activation/inactivation of target genes in IL-7-producing cells. With these IL-7-reporter mice, we identify thymus, skin and intestine as major sources of IL-7 in vivo. Importantly, we show that IFN-gamma and the commensal microflora promote steady-state IL-7 production in the intestine. Furthermore, we demonstrate that the blockade of IFN-gamma signaling in intestinal epithelial cells strongly reduces their IFN-gamma-driven IL-7 production. In summary, our data suggest a feedback loop in which commensal bacteria drive IFN-gamma production by lymphocytes, which in turn promotes epithelial cell IL-7 production and the survival of IL-7-dependent lymphocytes.

Ensheathing glia have been demonstrated to have neuroregenerative properties but this cell type from human sources has not been extensively studied because tissue samples are not easily obtained, primary cultures are slow growing, and human cell lines are not available. We previously isolated immortalized ensheathing glia by gene transfer of BMI1 and telomerase catalytic subunit into primary cultures derived from olfactory bulbs of an elderly human cadaver donor. These cells escape the replicative senescence characteristic of primary human cells while conserving antigenic and neuroregenerative properties of ensheathing glia, but their low proliferative rate in culture complicates their utility as cell models and their application for preclinical cell therapy experiments. In this study we describe the use of a conditional SV40 T antigen (TAg) transgene to generate human ensheathing glia cell lines, which are easy to maintain due to their robust growth in culture. Although these fast growing clones exhibited polyploid karyotypes frequently observed in cells immortalized by TAg, they did not acquire a transformed phenotype, all of them maintaining neuroregenerative capacity and antigenic markers typical of ensheathing glia. These markers were also retained even after elimination of the TAg transgene using Cre/LoxP technology, although the cells died shortly after, confirming that their survival depended on the presence of the immortalizing genes. We have also demonstrated here the feasibility of using these human cell lines in animal models by genetically marking the cells with GFP and implanting them into the injured spinal cord of immunosuppressed rats. Our conditionally immortalized human ensheathing glia cell lines will thus serve as useful tools for advancing cell therapy approaches and understanding neuroregenerative mechanisms of this unique cell type.
© 2011 Cognizant Comm. Corp.

Insulin-like growth factor (IGF) II is overexpressed in many human cancers and is reactivated by, and crucial for viral oncogene (SV40 T antigen, [TAg])-induced tumorigenesis in several tumor models. Using a double transgenic murine hepatic tumor model, we demonstrate that tissue inhibitor of metalloproteinase 1 (TIMP-1) blocks liver hyperplasia during tumor development, despite TAg-mediated reactivation of IGF-II. Because the activity of IGFs is controlled by IGF-binding proteins (IGFBPs), we investigated whether TIMP-1 overexpression altered the IGFBP status in the transgenic liver. Ligand blotting showed that IGFBP-3 protein levels were increased in TIMP-1-overexpressing double transgenic littermates, whereas IGFBP-3 mRNA levels were not different, suggesting that TIMP-1 affects IGFBP-3 at a posttranscriptional level. IGFBP-3 proteolysis assays demonstrated that IGFBP-3 degradation was lower in TIMP-1-overexpressing livers, and zymography showed that matrix metalloproteinases (MMPs) were present in the liver homogenates and were capable of degrading IGFBP-3. As a consequence of reduced IGFBP-3 proteolysis and elevated IGFBP-3 protein levels, dissociable IGF-II levels were significantly lower in TIMP-1-overexpressing animals. This decrease in bioavailable IGF-II ultimately resulted in diminished IGF-I receptor signaling in vivo as evidenced by diminished receptor kinase activity and decreased tyrosine phosphorylation of the IGF-I receptor downstream effectors, insulin receptor substrate 1 (IRS-1), extracellular signal regulatory kinase (Erk)-1, and Erk-2. Together, these results provide evidence that TIMP-1 inhibits liver hyperplasia, an early event in TAg-mediated tumorigenesis, by reducing the activity of the tumor-inducing mitogen, IGF-II. These data implicate the control of MMP-mediated degradation of IGFBPs as a novel therapy for controlling IGF bioavailability in cancer.