Evaluation of estrogenic effects of synthetic progestin norethindrone on human ovarian cancer cells in vitro and zebrafish in Vivo

Abstract

Epithelial ovarian cancer, constituting 90% of ovarian cancer cases, is a lethal gynaecologic malignancy. As per the Globocan 2020 report, India accounts for 76.5% of ovarian cancer cases and 77.5% of related deaths in South Central Asian countries. Chemoprevention remains crucial until advanced screening and therapies emerge. Using combined oral contraceptives for over 5 years is a highly protective factor, with an odds ratio of 0.44-0.54. This study investigated the effect of Norethindrone (NET) and 17and#945;-ethinylestradiol (EE2), frequently found in oral contraceptives, on human ovarian cancer cells (SKOV3) and the reproductive histology and gene expression in adult zebrafish. NET alone demonstrated dose-dependent reduction in SKOV3 cell viability, migration suppression, G2/M cell cycle arrest, increased intracellular ROS levels, apoptosis, and upregulated tumor suppressor genes. EE2 showed similar effects but less pronounced. Co-exposure yielded more significant results than EE2 alone, influenced primarily by NET. In vivo, NET did not affect the fish survival, while EE2 led to mortality, which was mitigated by co-administration. The reproductive histology was notably influenced by NET and EE2, causing delayed oocyte maturation in females and altered spermatogenesis in males, potentially guided by differentially regulated estrogen and progesterone receptors. The varying mRNA levels of vegfaa and tp53 genes after drug exposure, especially in males, hinted at potential carcinogenic effects, necessitating further scientific investigation. Overall, this study emphasizes the potential of Norethindrone in managing ovarian cancer yet warrants additional research to assess its benefits and latent unintended consequences on reproductive health in both human and aquatic environments. newline