Knockout of CD24 enhances phagocytosis of macrophages against triple-negative breast cancer
Objective To investigate the effect of CD24 knockout by triple negative breast cancer cell on macrophage phagocytosis.Methods Firstly,CD24-knockout triple-negative breast cancer cell line MDA-MB-231 was constructed by CRISPR-Cas9 and co-cultured with macrophages.Flow cytometry was used to detect the change of phagocytosis ratio of macrophages.Then,the effect of CD24 knockout by triple-negative breast cancer cell on phagocytosis of macrophages was verified by animal experiments.Finally,the expression of macrophage surface marker CD11b in unde mouse tumor tisues before and after CD24 knockout was verified by immunohistochemistry,and the proliferation ability of triple-negative breast cancer cells after CD24 knockout was detected by CCK-8 assay.Results After CD24 knockout,the phagocytic proportion of macrophages in the second quadrant(Q2)increased from 5.4％to 39.0％with statistical significance(P＜0.05),and the proportion of cells detected in the first quadrant(Q1)decreased from 23.8％to 15.8％(P＜0.05).The proportion of cells detected in the third quadrant(Q3)decreased from 67.3％to 41.4％(P＜0.05).The addition of CD24 antibody in the wild group enhanced the phagocytosis of macrophages(P＜0.05),but the addition of CD24 antibody in the CD24 knockout group did not change the proportion of phagocytes(P＞0.05).The experiment of subcutaneous tumor formation in mice showed that the tumor load decreased significantly after CD24 knockout(P＜0.05),and the weight of mice did not change significantly,but the tumor volume[(428±44)mm3 vs.(163±119)mm3]and tumor weight[(263±15)mg vs.(100±81)mg]decreased significantly and the difference was statistically significant(P＜0.05).There was no significant difference in the expression of CD11b in tumor tissues whether CD24 was knocked out or not(P＞0.05).Conclusion The phagocytic effect of macrophages on tumor cells can be enhanced by knocking out CD24 or using CD24 antibody,and CD24 is expected to be a potential target for inherent immunotherapy of tri ple-negative breast cancer.
Triple negative breast cancerCD24MacrophagePhagocytosisImmune escape
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