Purpose: Recent researches are attempting to verify that the 3D cell models can provide a gap bridge between in vitro and in vivo for anticancer drug evaluations. The aim of this study was to continue the development of novel in vitro 3D cell models and the investigation of the cellular uptake mechanism of camptothecin (CPT) and its derivatives [FL118 (10,11-methylenedioxy-20(S)-camptothecin), 9-Q20 (9-p-trifluoromethylphenyl-10,11-methylenedioxy-20(S)-camptothecin)] in 2D and 3D cell models.
Methods: The 3D cell models were established using ultralow attachment 96-well plates. The cytotoxicity of CPT, FL118, and 9-Q20 was evaluated by MTT method. The effects of compound concentration, incubation time, temperature, and transporter inhibitors on the cellular uptake of CPT, FL118, and 9-Q20 were examined in 2D and 3D cell models.
Results: The cytotoxicity of CPT, FL118, and 9-Q20 was lower in 3D cell models than 2D cell models. In 2D Caco-2 cell model, the uptake rate of CPT, FL118, and 9-Q20 was faster during the early time of incubation. In 3D Caco-2 cell model, the uptake capacity of CPT, FL118, and 9-Q20 was significantly improved over time. In 3D Caco-2 cell model, Verapamil (P-gp inhibitor) and Gefitinib (BCRP inhibitor) more significantly increased the uptake of CPT and 9-Q20. In contrast, P-gp and BCRP did not affect the accumulation of FL118 in 2D and 3D Caco-2 cell models. The accumulation of CPT, FL118, and 9-Q20 was greater in HepG2 cells than HCT116 cells.
Conclusion: The 3D cell models provided more potency information on the process of cellular uptake of CPT, FL118, and 9-Q20, which more objectively reflected the drug sensitivity and drug resistance in vivo compared with the 2D cell models.
Keywords: 3D culture; 9-Q20; Cellular uptake; Cytotoxicity; FL118; Ultralow attachment.