Transglutaminase 7 Silencing Inhibits Proliferation and Modulates Inflammatory and Apoptotic Markers in Testicular Germ Cell Tumors.

OBJECTIVE: Testicular germ cell tumors (TGCTs) represent the most common malignancy among young men aged 20-40 years. Transglutaminase 7 (TG7), encoded by TGM7, is a poorly characterized enzyme whose function in TGCT remains unknown. This study aimed to assess TG7 expression in clinical specimens and investigate its functional role in a testicular germ cell tumor cell line (NT2/D1). METHODS: TG7 protein expression was evaluated in clinical testicular tissue samples via immunohistochemistry (IHC) and immunofluorescence (IF). Functional analysis was conducted in the NT2/D1 human testicular cancer cell line using Dicer-substrate small interfering RNAs (DsiRNAs) targeting TG7. Gene knockdown efficiency was confirmed by reverse transcription quantitative PCR (qRT-PCR), and protein suppression was validated by immunofluorescence. Cell viability was assessed using the MTT assay. The expression of inflammation and apoptosis-related genes was quantified via qRT-PCR. RESULTS: TG7 expression was significantly elevated in testicular germ cell tumor tissues, showing approximately a 4.5-fold increase compared to normal testis, with strong localization in tumor nests and stromal compartments. In NT2/D1 cells, TG7 silencing using 20 nM DsiRNA3 led to a dose-dependent reduction in cell viability, with up to 48% inhibition observed at 200 nM (MTT assay, ****p < 0.0001). qRT-PCR analysis revealed significant upregulation of IL6 (3.2-fold), TNFα (2.8-fold), and CASP3 (2.5-fold) mRNA levels following TG7 knockdown (p < 0.0001), while p53 expression remained unchanged. These findings support TG7's role in modulating tumor cell survival, inflammation, and apoptosis via p53-independent pathways. CONCLUSION: Collectively, TG7 is significantly overexpressed in TGCT tissues and supports tumor cell viability in vitro. This study establishes TG7 as a novel biomarker and therapeutic target in testicular cancer, laying the groundwork for future studies on TG7-targeted interventions.