CHANGES IN THE EXPRESSION OF GAP JUNCTION PROTEINS (CONNEXINS) IN HAMSTER TONGUE EPITHELIUM DURING WOUND-HEALING AND CARCINOGENESIS

We examined changes in the expression and localization of connexin pro teins and transcripts by means of immunofluorescence and in situ hybri dization in normal conditions, wound healing and carcinogenesis using hamster tongue epithelium, in which differentiation, migration and gro wth of keratinocytes takes place physiologically and pathologically. I n normal hamster tongue epithelium, immunofluorescent staining showed that Cx26 and Cx43 proteins were localized differently during differen tiation of keratinocytes, but in in situ hybridization, the localizati on of Cx26 and Cx43 transcripts overlapped considerably, suggesting th at the different localization of Cx26 and Cx43 proteins in squamous ep ithelium is largely regulated at post-transcriptional levels, During w ound healing, the expression and localization of connexin proteins and transcripts were changed drastically, Shortly (6 h) after injury the expression of Cx26 and Cx43 proteins decreased at wound edges, but by 1-3 days after injury the expression of both proteins increased and bo th proteins co-localized to the same spots in the epithelium near woun d edges, During carcinogenesis, the increased expression of Cx26 and C x43 proteins and their transcripts and co-localization of both protein s occurred in papillomas, and the expression of Cx26 was reduced as ca ncer cells became morphologically less differentiated, We also found, that during wound healing in papillomas, squamous cell carcinomas and keratinocytes, Cx26 and Cx43 proteins were localized aberrantly in the cytoplasm, especially around nuclei, rather than on plasma membranes, These results indicate that quantitative and qualitative changes in c onnexin expression are associated with differentiation, migration and proliferation of keratinocytes in squamous epithelium.