Feasibility of the functional expression of the human organic anion transporting polypeptide 1B1 (OATP1B1) and its genetic variant 521T/C in the mouse liver

Pharmacogenetics of Drugs Used in the Treatment of Cancers

Pharmacogenomics is based on the understanding of the individual differences in drug use, the response to drug therapy (efficacy and toxicity), and the mechanisms underlying variable drug responses. The identification of DNA variants which markedly contribute to inter-individual variations in drug responses would improve the efficacy of treatments and decrease the rate of the adverse side effects of drugs. This review focuses only on the impact of polymorphisms within drug-metabolizing enzymes on drug responses. Anticancer drugs usually have a very narrow therapeutic index; therefore, it is very important to use appropriate doses in order to achieve the maximum benefits without putting the patient at risk of life-threatening toxicities. However, the adjustment of the appropriate dose is not so easy, due to the inheritance of specific polymorphisms in the genes encoding the target proteins and drug-metabolizing enzymes. This review presents just a few examples of such polymorphisms and their impact on the response to therapy.

Effect of OATP1B1 genetic polymorphism on the uptake of tamoxifen and its metabolite, endoxifen

Overexpression lentivirus platform was established of OATP1B1 (organic anion transporting polypeptides 1B1) wild‑type and mutant type genetic polymorphism in vitro, and using this platform we investigated and compared the uptake of tamoxifen and its metabolites by mutating the 388 and the 521 bases. The overexpression lentivirus cell platforms were successfully constructed, including OATP1B1*1a-HEK293T and OATP1B1*1b-HEK293T and OATP1B1*5-HEK293T cell model, the infection efficiency is not less than 80%. It shows a high level of gene expression at the mRNA and protein level. The tamoxifen and endoxifen can be taken up into the cells through organic anion transporter polypeptide 1B1, and OATP1B1521T>C inhibits the function of the transport protein, resulting in the content of drug in cell lysis liquid in OATP1B1*5-HEK293T group is lower than in OATP1B1*1a-HEK293T group (tamoxifen or endoxifen), with statistical significance. The content of the drug in cell lysis liquid in OATP1B1*1b-HEK293T group and the OATP1B1*1a-HEK293T group, similar with no statistical significance. These results suggest that tamoxifen and endoxifen can be transported by OATP1B1. However, OATP1B1 521T>C can inhibit the effects of OATP1B1 on tamoxifen and endoxifen in the cells.