SUN-203 Regulation Of Adrenal Androgen Production By Thyroid Hormones: Insights From The H295R Cell Model And Pediatric CAH Patients

Abstract Disclosure: P. Augsburger: None. T. Du Toit: None. S. Smit: None. C.E. Flueck: None. Introduction: Thyroid hormones (THs) play an essential role in the development, cellular differentiation and metabolism of the human body. Although TH action on various tissues has been well-described, the effect on the adrenal glands remains less understood. Recent studies have indicated a regulatory role for THs in adrenal cortex development and function. However, the regulation of adrenal androgen production by THs has yet to be clarified. Aim: To investigate the regulatory role of THs on androgen synthesis in human adrenocortical carcinoma H295R cells and to correlate TH levels to circulatory androgens in pediatric patients with congenital adrenal hyperplasia (CAH). Methods: H295R cells were incubated with triiodothyronine (T3) [10-9 M] in serum-free media for either 48 h or 72 h. Gene expression was assessed by mRNA-sequencing (cutoff value for padj < 0.001), and steroid profiling of cell supernatants was examined via liquid chromatography-mass spectrometry (LC-MS). In addition, serum samples of pediatric CAH patients with 21-hydroxylase deficiency were analyzed, obtained from a prospective, observational multi-center cohort study. At 1 or 2 consecutive visits, a targeted and untargeted panel of conventional adrenal and additional peripheral steroids were measured by LC-MS. Data of 83 visits from 70 children (39 boys, 31 girls; 33 prepubertal, 37 postpubertal) were available. Mean age was 11.0 [1.2; 18.9] years and BMI z-score was 0.51 [-1.84; 2.91]. Free thyroxine (fT4) was measured via chemiluminescence immunoassays. Regression analyses were adjusted for age, sex, BMI-z score, pubertal status (pre- and postpubertal), CAH subtype (salt-wasting, simple-virilizing, late-onset) and treatment quality (under-, over- and well-treated). Results: T3 downregulated dehydroepiandrosterone (DHEA) and DHEA-sulfate production in H295R cells by 29 % and 37 % respectively (p < 0.01), while slightly increasing T and A4 synthesis. This shift in the androgen profile is reflected by upregulated HSD3B2 (log2FC = 1.24) and AKR1C3 (log2FC = 0.64) gene expression, along with reduced CYP17A1 (log2FC = -0.42) transcripts. Likewise, in our CAH patients, we found a weak negative correlation for fT4 and serum DHEA (R2 = 0.251; p = 0.014), androstenedione (R2 = 0.368; p = 0.018) and androsterone (R2 = 0.323; p = 0.036), as well as for TSH and serum DHEA (R2 = 0.247; p = 0.018), androsterone (R2 = 0.338; p = 0.013) and 5a-DHT (R2 = 0.432; p = 0.023). Conclusion: We show that T3 decreases androgen precursor secretion, while increasing androgen secretion in adrenal H295R cells, mediated by changes in the expression of key steroidogenic enzymes. Furthermore, we found weak negative correlations between fT4 levels and serum androgen metabolites in pediatric patients with CAH. Together, these results indicate that THs may play an intricate role in adrenal androgen production. Presentation: Sunday, July 13, 2025