Establishment Of P-glycoprotein Inhibitor Screening Model And Its Application To Compounds Evaluation

P-glycoprotein (P-gp), an important efflux transporter, not only plays a key role in drug absorption, distribution, metabolism and excretion (ADME), but also is one of the major cause of tumor multi-drug resistance (MDR). P-gp inhibitor screening and P-gp mediated drug transport study have attracted more and more attentions in drug research and development. In this thesis, firstly, caco-2 cell monolayer model was established and the integrity of monolayer was validated with trans-epithellal electric resistance (TEER) measurement and microstructure observation. Secondly, the 3D organoid model was established and its P-gp expression was comparable to that in intestine of mouse. Based on the application of ultrasonic cell disruptor and automatic microplate reader, a rapid and efficient method for P-gp inhibitor screening was developed. Thirdly, indinavir was chosen as the in vivo probe substrate to investigate the effects of compounds on P-gp via its pharmacokinetic (PK) studies. Both in vitro and in vivo models were applied to test herb monomers and small molecule compounds. Data showed Cucurbitacin E (CuE) not only inhibited the efflux of digoxin across caco-2 cell monolayer, but also prevented the transportation of Rhodamine 123 (Rh123) across 3D organoids. In addition, single dose co-administration of CuE with indinavir significantly increased Cmax and AUC0-t of indinavir,. and decreased its Vd and CL in SD rats. These results showed that CuE inhibited P-gp activity both in vitro and in vivo. Moreover, LN-505 and WG-491 inhibited the efflux of digoxin, but did not change the PK parameters of indinavir in vivo. Thus, LN-505 and WG-491 may only inhibit P-gp activity in vitro. In general, the established in vitro models (caco-2 cell monolayer and 3D organoid) and in vivo model (indinavir PK model) will be useful tools for P-gp mediated drug transport studies and P-gp inhibitor screening.