Fig. 2

DB-1310 suppresses the growth of tumor cells in vitro. (a) Surface HER3 was detected by FACS in tumor cell lines. HER3 expression was determined as the MFI. (b) Breast cancer, prostate cancer and lung cancer cell lines were cultured with DB-1310. Cell proliferation was measured by a CTG assay, and IC50 values were calculated using linear regression with GraphPad Prism. (c) SK-BR-3 and NCI-H441 cells were treated with DB-1310 or Hu3f8 at 30 nM or 90 nM, and P1021 at 3nM or 30nM for 48 h. The cell cycle was analyzed by FACS. (d) HEK293 cells were stained with CellTrace™ Far Red Dye to trace in analysis and cocultured with HER3-negative HEK293 or HER3-expressing HEK293-ERBB3 cells at a 1:1 ratio for 4 days in the presence of different treatments. Cells were stained with PI, and labeled cell killing was analyzed by FACS. (e) HER3-expressing HEK293-ERBB3 cells were labeled with CellTrace™ Far Red Dye and cocultured with PBMCs at a 1:20 ratio in the presence of DB-1310 for 6 h to access ADCC effect. Cells were stained with PI and subjected to flow cytometric analysis to determine the lysis rate of HEK293-ERBB3 cells. (f) Human serum complement and HEK293-ERBB3 cells were mixed and incubated with DB-1310 for 1 h. Complement-mediated lysis of target cells was measured by CytoToxi96® Non-Radioactive Cytotoxicity Assay kit