Targeting tumor-associated macrophage (TAM) mediated inhibition of T-cell migration in prostate cancer using epigenetic modifying agents.
166 Background: Cytotoxic T lymphocytes (CTLs) perform vital anti-tumor functions and are critical to the efficacy of many anticancer therapies. In prostate cancer, the characteristic paucity of activated CTLs within the tumor microenvironment (TME) may be a key factor in disease progression and likely underlies the limited role for immune checkpoint inhibitors (ICIs) in prostate cancer treatment. In this study, we utilized novel microfluidic technologies to evaluate whether TAMs may be driving the exclusion of T cells from the prostate TME and whether the immunosuppressive functions of TAMs could be modified by epigenetic modifying agents. Methods: Primary macrophages and autologous T cells were derived from peripheral blood samples of prostate cancer patients at the University of Wisconsin. Mono-, co-, and tri-culture systems of macrophages, T cells, and 22RV1 cells (androgen-dependent prostate cancer cell line) were cultured in 2D and 3D in microfluidic cell culture platforms. Culture systems were treated with the EZH2 inhibitors (EZH2i) DZNep or EPZ-6438 or left untreated. Macrophages were also treated with M1 (IFN-g) and M2 (IL-4) polarizing cytokines. Systems were analyzed for T cell migration as well as mRNA and protein expression in each cell population. Results: Autologous macrophages inhibited activated T cell migration towards tumor cells in a multi-cellular microscale TME. T cell migration was restored through treatment with EZH2i. Gene expression analysis identified that EZH2i altered macrophage gene expression in the unpolarized and M1/M2 polarized states. In particular, there was increased expression of genes involved in T cell recruitment/chemotaxis, including CXCL10, CXCL11, CXCL12, following EZH2i treatment. Conclusions: We used novel microfluidic technologies to model and analyze multicellular TMEs using primary, patient-derived cells. We demonstrate that TAM-mediated suppression of T cell migration is mediated, in part, through epigenetic pathways, which can be targeted with EZH2i. Treatment with EZH2i, alone or in combination other therapies such as ICIs, may enhance cytotoxic T cell migration and activity in primary prostate cancer.