RESUMO
Tight junctions (TJs) are cellcell adhesion structures frequently altered by oncogenic transformation. In the present study the role of human papillomavirus (HPV) 16 E7 oncoprotein on the sealing of TJs was investigated and also the expression level of claudins in mouse cervix and in epithelial MadinDarby Canine Kidney (MDCK) cells. It was found that there was reduced expression of claudins 1 and 10 in the cervix of 7monthold transgenic K14E7 mice treated with 17ßestradiol (E2), with invasive cancer. In addition, there was also a transient increase in claudin1 expression in the cervix of 2monthold K14E7 mice, and claudin10 accumulated at the border of cells in the upper layer of the cervix in FvB mice treated with E2, and in K14E7 mice treated with or without E2. These changes were accompanied by an augmented paracellular permeability of the cervix in 2 and 7monthold FvB mice treated with E2, which became more pronounced in K14E7 mice treated with or without E2. In MDCK cells the stable expression of E7 increased the space between adjacent cells and altered the architecture of the monolayers, induced the development of an acute peak of transepithelial electrical resistance accompanied by a reduced expression of claudins 1, 2 and 10, and an increase in claudin4. Moreover, E7 enhances the ability of MDCK cells to migrate through a 3D matrix and induces cell stiffening and stress fiber formation. These observations revealed that cell transformation induced by HPV16 E7 oncoprotein was accompanied by changes in the pattern of expression of claudins and the degree of sealing of epithelial TJs.