Biomedical subjects

Anders Hjerpe

Publications and source records attributed to Anders Hjerpe.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Synthesis and expression of mRNA encoding for different versican splice variants is related to the aggregation of human epithelial mesothelioma cells.

Malignant mesothelioma often has a biphasic growth pattern of epithelial and/or sarcomatous morphology. In culture, epithelial cells form aggregates, whereas fibroblast-like cells do not. Two human mesothelioma cell sub-lines, one with epithelial differentiation and the other with fibroblast-like phenotype were studied. We have previously shown (Dobra et al, 2000) that distinct types of the cell-associated syndecans are involved in the regulation of mesothelioma cell differentiation, whereas the role of matrix proteoglycans (PGs) remains unknown. This study was undertaken to examine whether cell aggregation of the epithelial mesothelioma cells correlates to the differential expression of the matrix PGs versican and perlecan at different degrees of confluence. PGs were isolated from the culture medium using ion-exchange chromatography and identified by high-performance liquid chromatography, capillary electrophoresis and Western blotting. Fibroblast-like cells express substantially more versican than epithelial cells. RT-PCR showed that both cell lines express mRNA coding for versican splice variants V0 and V1, but not for V2. The dominating splice variant in both cell lines is the V0. Screening of versican splice variants in various degrees of culture confluence showed that the expression of mRNA conding for the versican splice variants V0 and V1 is different only in confluent cultures. No significant differences in the expression of perlecan between the two cell lines were recorded. These results suggest that the aggregation of epithelial cells is related to a significant decrease (p < or = 0.001) of the splice variant V1. This variant seems to be a biologically active constituent that affects tumor biology.

Alternative Splicing↗

PubMedDate not supplied

Growth factors regulate the expression profile of their syndecan co-receptors and the differentiation of mesothelioma cells.

BACKGROUND: Diffuse malignant pleural mesotheliomas are locally aggressive and highly lethal tumors that are becoming more common. The tumor derives from pluripotential mesothelial stem cells, which differentiate into epithelial or mesenchymal elements. Tumors with a predominantly epithelial growth pattern have a better prognosis than the sarcomatous and mixed types, the phenotype being important for the biology of the tumor. We have previously shown that mesotheliomas express a wide range of cell surface heparan sulfate proteoglycans (HSPGs), particularly syndecans, which interact with growth factors and matrix components. MATERIALS AND METHODS: This study was undertaken to examine the epithelial-mesenchymal transition of mesothelioma cells by exposing epithelially-differentiated cells to an array of growth factors. Following substitution with TGF-beta 2, EGF, FGF-2, IGF-I and PDGF-BB, the expression levels of syndecans-1, -2 and -4 were monitored at selected times (30 minutes, 6 hours and 18 hours) by semi-quantitative RT-PCR and FACS analysis. The morphological appearance and proliferation rate of the treated cells was correlated to the PG profile obtained and to the subcellular compartmentalization of PGs. RESULTS: An early response was obtained only for syndecan-4. Changes in the differentiation pattern appeared later. Exposure to EGF and IGF-I induced a fibroblast-like morphology, simultaneously with a reduced expression of syndecans-1 and 2. TGF-beta 2 enhanced the focal contacts and showed a marked up-regulation of syndecan-4 and down-regulation of syndecan-1. Interestingly, TGF-beta 2 delayed the nuclear transport of syndecan-1 concomitantly with an antiproliferative effect. CONCLUSION: Growth factor signalling seems to be delicately controlled by an autoregulatory loop involving the syndecan expression levels and amounts of soluble HS chains shed into the medium.

Cell Differentiation↗

PubMedDate not supplied

Large matrix proteoglycans, versican and perlecan, are expressed and secreted by human leukemic monocytes.

THP-1 is a monocytic cell line originally derived from a patient with acute monocytic leukemia. Interactions of THP-1 cells with other cells and their microenvironment are largely determined by proteoglycans (PGs), the identity of which has not been determined. Previous studies on glycosaminoglycan expression by THP-1 cells and peripheral blood mononuclear cells from healthy individuals showed that both cell types secrete mainly chondroitin sulfate PGs to the culture medium, whereas heparan sulfate PGs are mainly retarded at the cell membrane. However, limited data on the type of PGs synthesized by THP-1 is available. In this study, the identification of PG types synthesised by THP-1 cells, which are not differentiated to macrophages, was examined. Analysis at the mRNA level by RT-PCR showed the expression of six cell membrane-associated PGs: syndecan-1, -2 and -4, glypican-1, thrombomodulin and CD44. Cell extraction, ion-exchange chromatography and dot blot analysis of the isolated PG populations with monoclonal antibodies showed the presence of syndecan-1 and thrombomodulin; the other two syndecans were not detected in any of the isolated populations. The synthesis of matrix PGs was also studied. THP-1 monocytes were positive for the mRNA encoding for versican and perlecan, but not for those encoding for decorin, biglycan, betaglycan and fibromodulin. The mRNA encoding for two versican splice variants V0 (351 bp) and V1 (386 bp), but not for V2, were identified. Biochemical analysis showed the presence of perlecan and of two populations of versican in culture medium with protein cores of average molecular sizes similar to those of V0 and V1. The production of these large matrix PGs by THP-1 monocytes is reported for the first time and may be of importance in monocyte malignant transformation and differentiation.

Chondroitin Sulfate Proteoglycans↗