Abstract: Objective To investigate the role of long non-coding RNA CASC19(the cancer susceptibility 19) in maintaining the polarized state of M1 macrophage and its effect on the growth of colorectal cancer cells. Methods Mononuclear lymphoma Thp1 cells were induced to degenerate into unpolarized macrophage M0, which were further induced to polarize into the classical activated M1 macrophage and the alternative activated M2 macrophage. The expressions of the M1 and M2 macrophage molecular markers and the CASC19 were detected by RT-qPCR, and the polarized state of macrophages and transfection efficiency of CASC19 were confirmed. The colorectal cancer cells SW480 were stimulated by the supernatant of M1 macrophage(M1 SI-MC group) and Negative control supernatant(M1 NC-MC group) that knocked down CASC19. Real-time dynamic imaging and MTS staining were used to assess the cell proliferation ability, and Transwell assays was used to measure the cell migration ability. Results RT-qPCR showed that polarized macrophages were successfully induced. The expression level of CASC19 in M1 macrophage was higher than that in M0 and M2 macrophage(P<0.05). Compared with the M1 NC-CM group, the supernatant of M1 macrophage with knocking down CASC19 had weaker inhibition on the proliferation and migration of colorectal cancer cells SW48（P<0.001）. After knocking down CASC19 in M1 macrophage, the expression levels of M1 molecular markers CD40 and IL-1β were decreased, while the expression levels of M2 molecular markers CD206, IL-10 and CD163 were increased(P<0.05). Conclusion CASC19 knockdown can weaken the inhibition of proliferation and migration of M1 macrophage on colorectal cancer cells, which may be achieved by eliminating the maintenance effect of CASC19 on the polarized state of M1 macrophage.

Key words:  , Colorectal cancer, Macrophages, Long non-coding RNA, CASC19, Polarized