Retinoids, sex steroids and glucocorticoids regulate ectocervical cell envelope formation but not the level of the envelope precursor, involucrin.

In spite of extensive study of the reproductive tract, little knowledge is available regarding the function of ectocervical epithelial (ECE) cells. In the present study we utilized a feeder layer of 3T3 cells to grow homogeneous cultures of human ectocervical epithelial cells and demonstrated the presence of the cornified envelope precursor, involucrin. Treatment of these cultures with 1 nM Ro 13-6298, a synthetic analogue of trans-retinoic acid, suppresses envelope formation 6-fold with half-maximal suppression at 0.005-0.01 nM. Treatment with 1 microM hydrocortisone elevates envelope production 2.5-fold. Sex steroids also regulate desquamation: 10 nM diethylstilbestrol, a synthetic estrogen, increases envelope levels 2- to 3-fold, while 300 nM progesterone reduces envelope production 2- to 3-fold. In spite of the retinoid-, glucocorticoid- and sex-steroid-stimulated changes in envelope production, the level of the envelope precursor, involucrin, remains constant. Our results suggest: (1) that, in vivo, ectocervical cell squame formation is regulated by the combined direct action of estrogens, progestins, glucocorticoids and retinoids; and (2) that envelope formation is not regulated by changes in the cellular content of the envelope precursor, involucrin. We present a model summarizing the estrogen, progestin, glucocorticoid and retinoid effects on ectocervical epithelial cell function.