Deficiency of DAZ genes links testicular germ cell tumorigenesis and infertility: evidence from human embryonic stem cell germline differentiation

Y-chromosome AZFc deficiency, which includes the DAZ gene family, is one of the most common genetic causes of severe male infertility. Epidemiological and molecular evidence suggest a developmental link between abnormalities in germ cell development and testicular germ cell tumor (TGCT), but whether and how DAZ deficiency is associated with TGCT susceptibility remains unclear. Using a specific human embryonic stem cell (hESC) model, we constructed and characterized a DAZ-deleted cell line (SKLRMe001-A) and compared its efficiency of induction into human primordial germ cell-like cells (hPGCLCs) with that of the H1 control line. We assessed intersections between embryonic-like networks and HMGA1-P53-MAPK/PI3K pathways to explore the potential connection between DAZ deficiency and TGCT susceptibility. DAZ deficiency significantly reduced hPGCLC induction efficiency and downregulated early lineage markers such as SOX17, BLIMP1, and TFAP2C, accompanied by S-phase shortening, cell cycle dysregulation, and increased apoptosis. RNA sequencing and enrichment analyses indicated sustained upregulation of HMGA1 and pointed to dysregulated homeostasis of P53 stress responses and PI3K/AKT and MAPK signaling axes. These findings are consistent with features of TGCT, including maintenance of embryonic-like programs, activation of proliferative signals, and heightened DNA damage responses. Therefore, we propose that lineage differentiation defects and mismatches between stress and survival signaling caused by DAZ deficiency may produce in vivo a population of "undifferentiated and susceptible" cells that increase the risk of TGCT, while also explaining the developmental basis of male infertility. Using a human in vitro model, this study links DAZ deficiency to both infertility and TGCT susceptibility and identifies HMGA1 as a central transcriptional-signaling hub. This finding provides molecular clues for risk stratification and early surveillance in populations with DAZ deficiency and suggests that interventions targeting HMGA1 and the PI3K/AKT and MAPK pathways may simultaneously improve germline differentiation and reduce potential tumor risk.