Type IV procollagen mRNA regulation: evidence for extracellular matrix/cytoskeleton/nuclear matrix interactions in human urothelium.

The absence of basement membrane components correlates with tumor stage and progression in human bladder cancers. We have previously shown that invasive tumors possess the ability to degrade basement membrane. However, the presence of basement membrane may be affected not only by its degradation, but by its synthesis and deposition as well. Our results in the present study suggest that while the invasive human transitional carcinoma cell line EJ has an increased amount of type IV procollagen mRNA when compared to the non-invasive RT4 cell line, type IV collagen staining is absent in the invasive EJ cells and intensely present in the non-invasive RT4 cells. Moreover, when EJ cells were grown on an artificial basement membrane (Matrigel), type IV procollagen mRNA expression was down-regulated to the levels seen with the non-invasive RT4 cells. We also discovered that the invasive cells, when grown on Matrigel, appeared morphologically different from the same cells grown on plastic tissue cultures. We conclude that a deficient basement membrane in invasive cancer cells may be due not only to active proteolytic activity but also to an abnormal production and deposition of extracellular matrix components. In addition, we also demonstrated that basement membrane components may have a significant effect on epithelial cell morphology and gene regulation, and that any alterations of the extracellular matrix-cytoskeleton-nuclear matrix interactions can lead to altered gene regulations and cell function.