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.