Differential expression of type I cytokeratins in hamster cheek pouch epithelium following treatment with dimethylbenzanthracene.

Abstract

Cytokeratin (CK) expression in untreated, paraffin-treated or dimethylbenzanthracene (DMBA)-treated hamster cheek pouch epithelium was investigated utilizing monoclonal antibodies AE1 or AE3, which react with type I or type II CKs, respectively, and by in situ hybridization utilizing type I CK-specific probes. The latter were isolated from a cDNA library of hamster cheek pouch mRNA and designated CK 13 and CK 10 based on their respective homologies (> 95% amino acids) with murine CK 13 and human CK 10. Treatment of hamster cheek pouch epithelium with DMBA resulted in increased expression of type I CK, detected immunohistochemically with monoclonal AE1, but decreased expression of type II CKs detected with AE3. Despite an overall increase in type I CKs, in situ hybridization demonstrated differential expression of type I CKs with altered distribution of CK 13 mRNA and reduced expression of CK 10 mRNA, providing additional sensitive markers for DMBA-associated changes in CKs. These changes were constant at 2 to 22 weeks in the pre-neoplastic and neoplastic epithelium following the initial application of DMBA.