Androgens Modulate Tumor–Immune Interactions in Testicular Germ Cell Tumors

BACKGROUND: The majority of testicular germ cell tumors (TGCT) are derived from the germ cell neoplasia in situ and arise after puberty in the local presence of high levels of testosterone. The seminoma subtype features a rich inflammatory infiltrate which impacts tumor progression but the role of testosterone in shaping tumor-immune interactions is yet unknown. OBJECTIVE: We characterized androgen receptor and associated gene expression in the TGCT microenvironment and investigated the impact of dihydrotestosterone (DHT) on seminomatous tumor cells as well as stimulated T cells and monocytes. As an in vitro model of the seminoma microenvironment, cocultures of TCam-2 cells with immune cell subtypes were analyzed in the presence of DHT. MATERIAL AND METHODS: Gene expression was analyzed in tumorous and nontumorous tissue specimens from TGCT patients and TGCT cell lines. Bulk and single-cell RNA-sequencing data were used for validation. T cells and monocytes were isolated from the blood of healthy individuals and either activated in vitro or cocultured with TCam-2 cells. Proliferation and metabolic assays, quantitative RT-PCR, flow cytometry, and ELISA were employed to assess the impact of DHT on tumor and immune cells. RESULTS: Androgen receptor and related gene expression was demonstrated in tumorous tissue from patients, TGCT cell lines, and activated primary immune cells, which was supported by the analysis of published RNA-seq data sets. DHT exerted only a minor effect on TCam-2 cells, whereas hormone treatment markedly mitigated T cell and monocyte activation in a dose-dependent manner. In addition, DHT modulated immune cell activity and selected features of TCam-2 cells in T cell and monocyte cocultures serving as an in vitro model of the seminoma microenvironment. DISCUSSION AND CONCLUSION: Our results suggest that androgens present in tumorous testis of TGCT patients could impact tumor-immune interactions and thereby clinical outcome.