Fig. 1: RC48 significantly inhibited cell proliferation in HER2-positive CRC cell lines.

A DR5 mRNA overexpression in human CRC versus normal colon. Box plot has been downloaded from the GEPIA database. B Percent of 538 CRC tumors in each of the four staining intensity, including strong, moderate, low, and negative. C Representative pictures of the 4 staining intensity of HER2 IHC on human CRC tumor tissue microarray. D The expression of human HER2 in COLO205, P53R, RKO and HCT116 cells quantified by Western blotting. E Plasma membrane and intracellular subcellular localization of HER2 protein (green) by immunofluorescence in COLO205, P53R, RKO and HCT116 cells. Overlay with DAPI (blue) is depicted. F P53R, RKO, COLO205 and HCT116 cells were treated with RC48, T-DM1, T-DXd and trastuzumab for 72 h, respectively. The cell viability was detected by Cell Titer-Glo Cell Viability assay. G P53R, RKO, COLO205 and HCT116 cells were treated by 0, 1 and 5 μg/ml RC48 for 48 h, then cell proliferation was determined by the EdU assay. Fluorescence images were obtained and analyzed with a fluorescence microscope. Data are presented as means ± SEM of three independent experiments. Images captured at 400×magnification, respectively. Scale bars = 20 µm. Data represent the mean ± SEM of at least three independent experiments and statistical significance was assessed by unpaired T-test (*p < 0.05; **p < 0.01; ***p < 0.001).