PREVENTION OF CARCINOMA IN-SITU OF HUMAN PAPILLOMAVIRUS TYPE 16-IMMORTALIZED HUMAN ENDOCERVICAL CELLS BY RETINOIC ACID IN ORGANOTYPIC RAFT CULTURE

Objective: To determine the effect of retinoic acid on the development of severe dysplasia or carcinoma in situ from endocervical cells cont aining human papillomavirus (HPV) type 16. Methods: Two independent li nes of HPV 16-immortalized endocervical cells were reconstructed into two squamous epithelial tissues using the organotypic raft culture sys tem to examine the differentiated phenotype. The effect of retinoic ac id on dysplastic morphology of differentiation of the epithelia was ex amined by light microscopy of stained sections and electron microscopy . The endocervical cell type cytokeratin expression pattern was determ ined by indirect immunofluorescence using specific monoclonal antibodi es. Ribonucleic acid expression of the HPV 16 E7 oncogene was examined by in situ hybridization. Results: Untreated HPV 16-immortalized endo cervical cells were reconstructed into squamous dysplastic lesions res embling carcinoma in situ observed in women. Retinoic acid-treated raf ts formed epithelia composed of two to three cell layers of columnar-l ike cells resembling simple epithelium of the endocervix. Electron mic roscopy and cytokeratin expression patterns confirmed the histology of a differentiated endocervical phenotype after treatment with retinoic acid. Expression of HPV 16 E7 was modestly lower in treated epithelia , preferentially in basal cells. Conclusion: Retinoic acid prevents th e histology and cytokeratin differentiation markers of carcinoma in si tu of HPV 16-immortalized endocervical cells. Because the epithelia cl osely mimic HPV 16-containing severe dysplasias and native endocervica l epithelium in women, this immortalized endocervical cell-raft system may be useful as a model to assess the efficacy of agents such as ret inoic acid for preventing progression of these lesions to malignant ce rvical carcinoma.