Testis Molecular Pathways in CAIS Unveil Testosterone/Estradiol on Germ Cell Tumor Risk in Non-Obstructive...

Non-obstructive azoospermia (NOA) is the most severe form of male infertility, affecting 1% of all men, with a clinical picture characterized by no sperm production, hyalinization of the basal membrane of the seminiferous tubules, primary hypogonadism, and earlier onset of age-related comorbidities compared with fertile men. NOA is also characterized by etiologic heterogeneity and the non-genetic form has higher incidence of testicular germ cell cancer (TGCC) compared to the forms with genetic abnormalities.

We aimed to establish molecular pathways in the testicular somatic cells that are either shared or specific for non-genetic and genetic forms of NOA, such as complete androgen insensitivity syndrome (CAIS) and Klinefelter syndrome (KS).

We performed single-cell RNA sequencing of the testicular somatic cells of an individual with CAIS, and data integration with published scRNA-seq datasets of testis with normal spermatogenesis, NOA, KS, and germinal testicular cancer. Detailed clinical data of the CAIS patient, testosterone and estradiol levels in age-matched men (120 fertile, 155 infertile, 116 NOA, 18 KS, and 343 with TGCC) were analyzed.

In all conditions, Leydig cells are immature and senescent, but those of NOA associated with primary hypogonadism depict the highest expression of transcripts associated with the seminoma microenvironment, including estrogen-responsive genes. An oncological transcriptional signature in the Leydig cells has been confirmed at the systemic levels by showing a prognostic role of the decreasing testosterone/estradiol ratio for TGCC in men with non-genetic NOA.

This study offers molecular insights into the prediction of TGCC in persons with NOA and eligibility for the use of aromatase inhibitors.