Regulation of PDGF chain and receptor expression in human malignant mesothelioma cell lines

In normal, untransformed cells, growth is a tightly regulated process, A single cell is capable of controlling its growth by integrating the input from both positive growthstimulating and negative growth-inhibiting signals. Unrestrained cell proliferation is the hallmark of carcinogenesis and arises as a consequence of aberrations in this normal growth control. The importance of such disturbed growth-regulating mechanisms is underscored by the observation that in vitro tumour cells were found to proliferate independently of exogenous growth factors. The apparent ability to be able to grow without mitogenic factors supported the earlier suggestion of Temin that growth of transformed cells may be caused by endogenous production of growth factors. This concept was later extended to the autoerine growth stimulation model. It has become generally accepted that genetic damage is a central event in the process of loss of growth control. Disturbances in the growth-regulating mechanisms by changes in the genes til at govern these processes, consequently enable cells to escape normal growth control. Genes, whose products contribute to uncontrolled growth, once they are genetically altered, can be classified as oncogenes and tumour suppressor genes. In the former category such genetic alterations give rise to a gain-of-function resulting in positive growth stimulation (e.g. by changes in growth factor-encoding genes), whereas in the latter growth-inhibiting properties are lost

A very low thymus function identifies patients with substantial increased risk for long-term mortality after kidney transplantation

Background: End-stage renal disease is associated with premature ageing of the T cell immune system but inter-individual variation is substantial. The hypothesis was tested that advanced immunological T cell ageing assessed by peripheral T cell differentiation increases the long-term mortality risk after renal transplantation. Results: Circulating T cells of 211 recipients of a kidney from a living donor were analyzed before and in the first year after transplantation. The number of CD31-positive naive T cells (as a marker for recent thymic emigrants) and the differentiation status of the memory T cells was assessed. Thirty recipients died during follow-up of at least 5 years. Absolute numbers of naive CD4+ (living:258 cells/μl vs. deceased:101 cells/μl, p < 0.001) and naive CD8+ T cells (living:97 cells/μl vs. deceased:37 cells/μl, p < 0.001) were significantly lower in the deceased group prior to transplantation. In a multivariate proportional hazard analysis the number of naive CD4+ T cells remained associated with all-cause mortality (HR 0.98, CI 0.98-0.99, p < 0.001). The low number of naive T cells in the deceased patient group was primarily caused by a decrease in recent thymic emigrants (i.e. less CD31+ naive T cells) indicating a lowered thymus function. In addition, the physiological age-related compensatory increase in CD31- naïve T cells was not observed. Within the first year after transp

Memento for interprofessional learning

The vast increase of technical, diagnostic, and treatment possibilities and deepened understanding of molecular biology has revolutionized diagnosis and treatment of cancer and thus has great impact on pathology. Different professionals are responsible for proper evaluation of the results and their translating into an accurate diagnosis and appropriate treatment. Next to expertise, a close interaction between clinical molecular biologists, pathologists, and oncologists is required; it is crucial that these professionals speak “the same language.” Key to this is communication skills and creating possibilities for collaboration in a meaningful context. Here, we present an interprofessional, educational workshop model and we describe the parameters that contribute to effective learning by specialists

Basic helix-loop-helix proteins E2A and HEB induce immature T-cell receptor rearrangements in nonlymphoid cells

T-cell receptor (TCR) gene rearrangements are mediated via V(D)J recombination, which is strictly regulated during lymphoid differentiation, most probably through the action of specific transcription factors. Investigated was whether cotransfection of RAG1 and RAG2 genes in combination with lymphoid transcription factors can induce TCR gene rearrangements in nonlymphoid human cells. Transfection experiments showed that basic helix-loop-helix transcription factors E2A and HEB induce rearrangements in the TCRD locus (Ddelta2-Ddelta3 and Vdelta2-Ddelta3) and TCRG locus (psi Vgamma7-Jgamma2.3 and Vgamma8-Jgamma2.3). Analysis of these rearrangements and their circular excision products revealed some peculiar characteristics. The Vdelta2-Ddelta3 rearrangements were formed by direct coupling without intermediate Ddelta2 gene segment usage, and most Ddelta2-Ddelta3 recombinations occurred via direct coupling of the respective upstream and downstream recombination signal sequences (RSSs) with deletion of the Ddelta2 and Ddelta3 coding sequences. Subsequently, the E2A/HEB-induced TCR gene recombination patterns were compared with those in early thymocytes and acute lymphoblastic leukemias of T- and B-lineage origin, and it was found that the TCR rearrangements in the transfectants were early (immature) and not necessarily T-lineage specific. Apparently, some parts

Expression of the Wilms' tumor gene WT1 in human malignant mesothelioma cell lines and relationship to platelet-derived growth factor A and insulin- like growth factor 2 expression

Mutations in the WT1 tumor suppressor gene are known to contribute to the development of Wilms' tumor (WT) and associated gonadal abnormalities. WT1 is expressed principally in the fetal kidney, developing gonads, and spleen and also in the mesothelium, which lines the coelomic cavities. These tissues develop from mesenchymal components that have subsequently become epithelialized, and it has therefore been proposed that WT1 may play a role in this transition of cell types. To test the possible involvement of this gene in malignant mesothelioma, we have first studied its expression in a panel of human normal and malignant mesothelial cell lines. WT1 mRNA expression levels varied greatly between the cell lines and no specific chromosomal aberration on 11p, which could be related to the variation in WT1 expression in these cell lines, was observed. Furthermore, no gross deletions, rearrangements, or functionally inactivating point mutations in the WT1 coding region were identified. All four WT1 splice variants were observed at similar levels in these cell lines. The WT1 gene encodes a zinc-finger transcription factor and the four protein isoforms are each believed to act as transcriptional repressors of certain growth factor genes. Lack of WT1 expression is thus predicted to result in growth stimulation of tumor cells. Binding of one particular WT1 isoform construct to the insulin-like growth factor 2 (IGF2) and platelet-derived growth factor A (PDGFA) gene promoters has been demonstrated to result in repression of these genes in transient transfection studies. Analysis of IGF2 and PDGFA mRNA expression levels compared with WT1 mRNA expression levels failed to demonstrate an inverse correlation in the mesothelial cell lines, which endogenously express these genes. Finally, the putative role of WT1 in the transition of cell types was investigated. No obvious correlation between WT1 expression levels and cell morphology of the malignant mesothelial cell lines was evident from this study. Moreover, no change in WT1 expression was observed in normal mesothelial cells which were, by alteration of culture conditions, manipulated to switch from the mesenchymal to epithelial morphology

End-stage renal disease causes skewing in the TCR Vβ-repertoire primarily within CD8+ T Cell subsets

A broad T cell receptor (TCR-) repertoire is required for an effective immune response. TCR-repertoire diversity declines with age. End-stage renal disease (ESRD) patients have a prematurely aged T cell system which is associated with defective T cell-mediated immunity. Recently, we showed that ESRD may significantly skew the TCR Vβ-repertoire. Here, we assessed the impact of ESRD on the TCR Vβ-repertoire within different T cell subsets using a multiparameter flow-cytometry-based assay, controlling for effects of aging and CMV latency. Percentages of 24 different TCR Vβ-families were tested in circulating naive and memory T cell subsets of 10 ESRD patients and 10 age- and CMV-serostatus-matched healthy individuals (HI). The Gini-index, a parameter used in economics to describe the distribution of income, was calculated to determine the extent of skewing at the subset level taking into account frequencies of all 24 TCR Vβ-families. In addition, using HI as reference population, the differential impact of ESRD was assessed on clonal expansion at the level of an individual TCR Vβ-family. CD8+, but not CD4+, T cell differentiation was

End stage renal disease patients have a skewed T cell receptor Vβ repertoire

Background: End stage renal disease (ESRD) is associated with defective T-cell mediated immunity. A diverse T-cell receptor (TCR) Vβ repertoire is central to effective T-cell mediated immune responses to foreign antigens. In this study, the effect of ESRD on TCR Vβ repertoire was assessed. Results: A higher proportion of ESRD patients (68.9 %) had a skewed TCR Vβ repertoire compared to age and cytomegalovirus (CMV) - IgG serostatus matched healthy individuals (31.4 %, P < 0.001). Age, CMV serostatus and ESRD were independently associated with an increase in shifting of the TCR Vβ repertoire. More differentiated CD8+ T cells were observed in young ESRD patients with a shifted TCR Vβ repertoire. CD31-expressing naive T cells and relative telomere length of T cells were not significantly related to TCR Vβ skewing. Conclusions: ESRD significantly skewed the TCR Vβ repertoire particularly in the elderly population, which may contribute to the uremia-associated defect in T-cell mediated immunity