A Coculture Model Mimicking the Tumor Microenvironment Unveils Mutual Interactions between Immune Cell Subtypes and the Human Seminoma Cell Line TCam-2

Abstract

Testicular germ cell cancer (TGCC) is the most common type of cancer in young men. Seminomas account for around half of them and are characterized by a pronounced infiltration of immune cells. So far, the impact of the tumor microenvironment (TME) on disease progression, especially the interaction of individual immune cell subtypes with the tumor cells, remains unclear. To address this question, we used an in vitro TME model involving the seminoma-derived cell line Tcam-2 and immune cell subsets purified from human peripheral blood. T cells and monocytes were strongly activated when individually cocultured with Tcam-2 cells as revealed by increased expression of activation markers and pro-inflammatory cytokines both on the mRNA and protein level. Importantly, the interaction between tumor and immune cells was mutual. Gene expression of pluripotency markers as well as markers of proliferation and cell cycle activity were upregulated in Tcam-2 cells in cocultures with T cells, whereas gene expression of SOX17, a marker for seminomas, was unaltered. Interestingly, the impact of monocytes on gene expression of Tcam-2 cells was less pronounced, indicating that the effects of individual immune cell subsets on tumor cells in the TME are highly specific. Collectively, our data indicate that seminoma cells induce immune cell activation and thereby generate a strong pro-inflammatory milieu, whereas T cells conversely increase the proliferation, metastatic potential, and stemness of tumor cells. Although the employed model does not fully mimic the physiological situation found in TGCC in vivo, it provides new insights potentially explaining the connection between inflammatory infiltrates in seminomas and their tendency to burn out and metastasize.

T cells in testicular germ cell tumors: new evidence of fundamental contributions by rare subsets

“…The role of pro-inflammatory cytokines in the TME is supported by an in vitro co-culture model using the human seminoma-like cell line TCam-2 and immune cell fractions, where TCam-2 cells induce immune cells activation and generate a strong pro-inflammatory milieu through producing IL-2, IL-6 and TNFα [ 52 , 56 , 57 ]. In addition, TCam-2 showed an immediate increase in pro-inflammatory cytokine mRNA levels ( IL-1β, IL-6, TNF-α , etc.)…”

T cells in testicular germ cell tumors: new evidence of fundamental contributions by rare subsets

“…The role of pro-inflammatory cytokines in the TME is supported by an in vitro co-culture model using the human seminoma cell line TCam-2 and immune cell fractions, where TCam-2 cells induce immune cells activation and generate a strong pro-inflammatory milieu through producing IL-2, IL-6 and TNFα (52, 56, 57). In addition, TCam-2 showed an immediate increase in pro-inflammatory cytokine mRNA levels (IL-1β, IL-6, TNF-α, etc.)…”

Testicular Germ Cell Tumor Tissue Biomarker Analysis: A Comparison of Human Protein Atlas and Individual Testicular Germ Cell Tumor Component Immunohistochemistry

“…The surrounding healthy testicular tissue with complete preserved spermatogenesis from TGCT patients is most readily available as a control for TGCT studies and is what the pathologist will see contrasting the tumor tissue, or while searching for GCNIS. However, it is known that TGCT dysregulates the testis and its microenvironment [54,55]. The testicles of TGCT patients may also be affected by testicular dysgenesis syndrome, which is related to TGCT, meaning that their testicular tissue may already be dysregulated [56,57].…”