Baicalin inhibits recruitment of GATA1 to the HSD3B2 promoter and reverses hyperandrogenism of PCOS.

Jin Yu,Yuhuan Liu,Zailong Cai,Chaoqin Yu,Dongxia Zhai,Danying Zhang,Linyi Song

doi:10.1530/joe-18-0678

Abstract

High androgen levels in patients suffering from polycystic ovary syndrome (PCOS) can be effectively reversed if the herb Scutellaria baicalensis is included in traditional Chinese medicine prescriptions. To characterize the effects of baicalin, extracted from S. baicalensis, on androgen biosynthesis in NCI-H295R cells and on hyperandrogenism in PCOS model rats and to elucidate the underlying mechanisms. The optimum concentration and intervention time for baicalin treatment of NCI-H295R cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and enzyme-linked immunosorbent assays. The functional genes affected by baicalin were studied by gene expression profiling (GEP), and the key genes were identified using a dual luciferase assay, RNA interference technique, and genetic mutations. Besides, hyperandrogenic PCOS model rats were induced and confirmed before and after baicalin intervention. As a result, Baicalin decreased the testosterone concentrations in a dose-and time-dependent manner in NCI-H295R cells. GEP revealed that 3β-hydroxysteroid dehydrogenase type II (HSD3B2) was the key enzyme of androgen biosynthesis, and baicalin inhibited the expression of HSD3B2 by regulating the binding of transcription factor GATA-binding factor 1 (GATA1) to the HSD3B2 promoter. Hyperandrogenic PCOS model rats treated with baicalin significantly reversed the high androgen levels of serum and the abnormal ovarian status, restored the estrous cyclicity, and decreased the expression of HSD3B2 in ovarian. In summary , our data revealed that GATA1 is an important transcription factor activating the HSD3B2 promoter in steroidogenesis, and baicalin potentially be an effective therapeutic agent for hyperandrogenism in PCOS by inhibiting the recruitment of GATA1 to the HSD3B2 promoter in ovarian tissue.

Highlights

gene expression profiling (GEP) analysis showed that a total of 893 genes (555 upregulated and 338 downregulated) were differentially expressed between the baicalin and control (0.1% DMSO) groups
After validation of the reliability of the profile data, the biological processes involving differentially expressed genes (DEGs) were identified by Gene Ontology (GO) enrichment analysis using the Database for Annotation, Figure 1 (A) Cytotoxicity of baicalin for NCI-H295R cells, as measured by the MTT assay
It is well known that Polycystic ovary syndrome (PCOS), which is characterized by accumulation in ovaries of incompletely developed follicles, due to anovulation, is a highly prevalent heterogeneous syndrome of the menstrual cycle and an endocrine dysfunction with clinical and/or biochemical hyperandrogenism, according to the Rotterdam criteria (Sirmans & Pate 2013)

Summary

Introduction

Hyperandrogenism in PCOS patients is of both ovarian and adrenal origin (Yu et al 2017), and it may manifest in mid-childhood as premature exaggerated adrenarche (Dorn et al 2008) and persists beyond the menopausal transition (Markopoulos et al 2011). A group of 3β-hydroxysteroid dehydrogenase (HSD3B) enzymes plays a central role early in this network during the biosynthesis of Δ4 androgens (Udhane et al 2013). HSD3B2 is crucial for the production of sex steroids and plays an essential role in the androgen biosynthesis both in health and disease (Miller & Auchus 2011)

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