Effect of Glucocorticoid Hormones on Viral Gene Expression, Growth, and Dysplastic Differentiation in HPV16-Immortalized Ectocervical Cells

Steroid hormones are proposed to act as cofactors with human papillomaviruses (HPVs) in the etiology of cervical cancer. We and others reported that progesterone and glucocorticoid hormones induce the expression of HPV16 via three glucocorticoid response elements (GREs) in the viral regulatory region. Consensus GREs (GREcs) are useful in other systems for examining the effect of hormones after enhancing the response with mutated GREc constructs. Therefore, this study used human ectocervical cells (HEC) and HPV type 16 containing three GREcs to establish immortalized cells (HEC-16GREc). Northern blot assays showed that the level of viral E6–E7 oncogene RNA was increased by hormones substantially more in HEC-16GREc than in wild-type HPV16-immortalized human ectocervical cells (HEC-16). The saturation density and the hormone response of the growth rate were significantly higher for HEC-16GREc and the doubling was faster in the presence of hormone than for HEC-16. Although both were nontumorigenic, only HEC-16GREc showed anchorage-independent growth, which was dependent on hormone. Also, HEC-16GREc were more abnormal in their epithelium differentiation pattern in organotypic (raft) cultures. Furthermore, hormone-treated HEC-16GREc rafts showed more dysplastic features than hormone-treated HEC-16 rafts. These results suggest new features of the role of hormones: that enhanced expression of viral oncogenes in response to hormones apparently confers a greater risk for cervical cells containing HPV16. Further, HEC-16GREc could be ideal for studying hormone-dependent and -independent malignant transformation.