17β-estradiol and progesterone effect on human papillomavirus 16 positive cells grown as spheroid co-cultures

Human papillomavirus (HPV) is the key epidemiologic factor of cervical cancer, but additional cofactors are mandatory. Estrogen has been considered as one of those. Here, the aim was to study the effects of steroid hormones on HPV16 E6-E7, estradiol receptors ERα and ERβ, and progesterone receptor (PR) in HPV16-positive cervical carcinoma cell lines SiHa and CaSki grown as epithelial and fibroblast spheroid co-cultures. The spheroid co-cultures were exposured to 17β-estradiol or progesterone from day 7 onwards. mRNA levels of HPV16 E6-E7, ERα, ERβ and PR normalized against GAPDH were analyzed with quantitative reverse transcription-qPCR (RT-qPCR). 17β-estradiol and progesterone decreased HPV16 E6-E7 mRNA expression in CaSki and increased in SiHA co-cultures. In CaSki co-cultures, ERβ expression was blocked after 17β-estradiol exposure while in SiHa cells it slightly increased ERβ expression. PR expression was seen only in CaSki spheroids and it vanished after exposure to steroid hormones. Fibroblasts expressed all three hormone receptors as monolayers but ERβ expression decreased and ERα and PR vanished after co-culturing. Cell culturing platform changes both oncogene and hormone receptor expression in HPV16 positive cervical cancer cell lines. This needs to be considered when in vitro results are extrapolated to in vivo situations.