Fig. 3: The transmembrane domain was highly required for MUC1 induced drug resistance.
A Immunofluorescence assay using MUC1 and Lamin B1 antibody was performed to confirm the MUC1 distribution in WT and R-MUT cells. Blue: Hoechst for nuclear staining; Red: Lamin B1 for nuclear membrane staining; Green: MUC1 staining. In WT cells, MUC1 evenly distributes on cell surface; however, the mutant MUC1 gathered in the cytoplasm and cannot anchor on cell membrane due to the TM deletion. B IC50 of four cell lines (namely WT, KO, re-expressed WT MUC1 in KO cells (R-WT) and re-expressed mutant MUC1 in KO cells (R-MUT)) treated with various concentrations of apigenin for 48 h. C Cell viability of re-constitutively expressed MCF-7 cells treated with indicated dose of apigenin for 48 h. D IC50 of empty vector, WT_MUC1 and TMdel_MUC1 plasmids transfected 293 T cell lines treated with various concentrations of apigenin for 48 h. E Colony formation of empty vector, WT_MUC1 and TMdel_MUC1 plasmids transfected 293 T cell lines treated with 25 μM apigenin for a week. F The quantification of E. G Cell viability of empty vector, WT_MUC1 and TMdel_MUC1 plasmids transfected 293 T cell lines treated with indicated dose of apigenin for 48 h. Each group was analyzed in triplicate. *P < 0.05; **P < 0.01; ***P < 0.001 for comparisons.
