Figure 4. Growth inhibition of melanoma cells by HER2Bi-armed ATC.

Malme-3M-luc cells were seeded (2 x10⁴/well) into 96-well round bottom microplate in triplicates overnight. On the following day, the medium was removed, and fresh medium alone or containing the unconjugated mAbs OKT3 or Herceptin (1μg/ml), ATC (2 x10⁵/well), HER2Bi-armed ATC (2 x10⁵/well, armed with 50 ng/HER2Bi/10⁶ ATC) or a combination of OKT3 and Herceptin® with ATC (unarmed ATC) for 18 hours. (A) Real-time photographs were taken at 200x magnification. a. Malme-3M-luc targets alone; b. Malme-3M-luc with OKT3; c. Malme-3M-luc with Herceptin; d. Malme-3M-luc with ATC; e. Malme-3M-luc with unarmed-ATC; f. Malme-3M-luc with HER2Bi-armed ATC. HER2Bi-armed ATC, but not ATC or unarmed ATC aggregated with Malme-3M-luc tumor cells in culture after 18 hours incubation. (B) The proliferation of Malme-3M-luc was assessed by CCK8 assay with the OD value measured at 450 nm. The data are mean ± SD of triplicate experiments, and a representative experiment of three was shown. Statistical analysis was conducted using Student’s t-test. *: P<0.01, HER2Bi-armed ATC compared with combination of the OKT3 and Herceptin with ATC under similar conditions.