Endocrine Abstracts

Background: Patients with complete androgen insensitivity syndrome (CAIS) have a genetic defect in the androgen receptor, resulting in female external genitalia and intra-abdominal testes. Although these intra-abdominal testes serve as a critical source of endogenously regulated steroid hormones during puberty, studies indicate that prioritizing estrogenic over androgenic activity is of greater clinical relevance in the management of CAIS. Therefore estrogenic pathways are of primary importance, with estrogen therapy generally being preferred over testosterone due to superior patient tolerance. This study aims to redirect steroidogenesis from testosterone toward estrogen by transfecting Leydig cells with an aromatase (Cyp19a1) construct.

Methods: The murine Leydig cell line (MLTC-1) served as a proof-of-concept model. Cells were transfected with a construct with CMV promoter driving Cyp19a1 expression for periods of 24 and 48 hours. To evaluate the shift in the steroidogenic profile, cell supernatants were collected at both time points. The concentrations of androgens and estrogens were subsequently quantified using Liquid Chromatography-Mass Spectrometry (LC-MS).

Results: Transfection was successful, with confirmed expression of the construct in the MLTC-1 cells. Data indicated that the expression of aromatase significantly increased estrogen concentration in the supernatant after 24 hours. Dihydrotestosterone (DHT) levels were simultaneously reduced. Testosterone production levels remained unaffected by the transfection. These results validate the ability to enhance the conversion of testosterone into estrogens within the primary androgen-producing cells of the testis.

Conclusions: The preliminary in vitro findings demonstrate that tissue-specific modulation of the estrogen synthesis is feasible. Future research will transition to in vivo mouse models using an AAV-based delivery approach to target the testes and gonadal adipose tissue. This approach offers a promising outlook for achieving systemic physiological hormone regulation. A further objective of this study is to optimize the conversion efficiency and conduct a more detailed analysis of the underlying mechanisms, as no significant reduction in testosterone concentrations has yet been observed.