Generation of Papillomavirus-Immortalized Cell Lines from Normal Human Ectocervical, Endocervical, and Vaginal Epithelium that Maintain Expression of Tissue-Specific Differentiation Proteins1
We have established and characterized three cell lines from normal human vaginal, ectocervical, and endocervical epithelia immortalized by expression of human papillomavirus 16/E6E7. The lines (VK2/E6E7, Ect1/E6E7, and End1/E6E7) displayed distinctive morphologies at the level of light microscopy when cultured in calcium-supplemented (0.4 mM) keratinocyte serum-free medium and maintained a stable phenotype after more than 1 yr of continuous passage. They were compared to primary cell cultures and epithelial cells in sections of the respective native tissues for expression of epithelial differentiation proteins. All cell lines expressed cytokeratin (CK) 8, CK18, and CK19, and some cells in all three cell lines expressed CK16, involucrin, and the secretory component of the polymeric immunoglobulin receptor. The vaginal and ectocervical cell lines expressed CK10 and CK13, whereas the endocervical line did not. With the exception of CK8 and CK18 expression, the morphological and immunocytochemical characteristics of the immortalized lines closely resembled those of their respective tissues of origin and primary cultures, and all differed significantly from the HeLa cervical adenocarcinoma cell line. These new cell lines may provide the basis for valid, reproducible in vitro models for studies on cervicovaginal physiology and infections and for testing pharmacological agents for intravaginal application.