Murine prostate cancer model: microenviroment macrophage populations and tumoral development vary within two C57BL/6 mice breeding nuclei from same substrain

Cancer mice models are critical for immune-oncology research; they provide conditions to explore tumor immunoenviroment aiming knowledge advance and treatment development. Often, research groups breed their own mice colonies. To assess the effect of C57BL/6 mice breeding nuclei in prostate cancer development and intratumoral macrophage populations, a isotransplantation experiment was performed. C57BL/6J mice from two breeding nuclei (nA and nB) were employed for prostate adenocarcinoma TRAMP-C1 cells implantation, tumor growth period and intratumoral macrophage profile were measured. 54% of BL/6nB mice showed tumor implantation and growth period was 69 days, meanwhile BL/6nA implantation reached 100% and tumor growth occur in 28 days. No difference of total macrophage populations was observed between groups within several tumoral regions, significant higher M2 macrophage profile were founded in tumor microenviroment from both mice groups. Nevertheless, BL/6nB tumors showed around twice populations of M1 profile (11% -27%) than BL6nA (4% -15%) and less non-polarized macrophages. M2:M1 average ratio was 8:1 for A group and 4.2:1 for B. Our results demonstrate different tumor progression and intratumoral macrophage populations among mice from same substrain. Data obtained in this study shows the relevance of animal sources renewing for better control of murine cancer model variables.