P314 Characterization of Bcrp Knock-out Rat Model Using Gene Expression Analysis

Eskouhie H. Tchaparian , Pkdm, Amgen Inc., South San Francisco, CA
Adria Colletti , Pkdm, Amgen Inc., South San Francisco, CA
John Roberts , Pkdm, Amgen Inc., South San Francisco, CA
Lixia Jin , Pkdm, Amgen Inc., South San Francisco, CA
Purpose: Breast cancer resistance protein, BCRP (ABCG2) is an important efflux transporter that plays a role in the absorption, distribution, and excretion of some drugs. Animal gene knock out technology is a valuable research tool for understanding gene function. To understand its potential use as an animal model for drug discovery support, the aim of the present study was to characterize the newly developed Bcrp Knockout (KO) rat model (SAGE Labs, St Louis, MO). Gene expression analysis was used to assess the effect of Bcrp gene deletion on drug metabolizing enzymes and transporters. Methods: RNA was extracted from liver, kidney, small intestine (jejunum, ileum, and duodenum), colon, and brain capillary enriched samples. Relative gene expression changes of drug metabolizing enzymes and transporters in the KO Bcrp rat relative to their wild type (WT) were evaluated by real-time RT-qPCR. Results: As expected, the results demonstrated the deletion of the target gene (Bcrp). Additionally, low expression levels of hepatic Mdr1 (2.7 fold mdr1b and 5 fold mdr1a), Mrp1 (3 fold) and Mrp5 (more than 10 fold) were detected. No significant change in the kidney gene expression was observed, while about three fold increase in Slc10a2 (Ileum and colon segments) and Mrp6 (duodenum and jejunum segments) was seen. The results also indicated significant decrease in the Cyp3a18 mRNA levels (~ 10 fold) in the ileum. Conclusion: Overall the result of this study indicates that in addition to Bcrp deletion, the expression level of some transporters is changed, specifically in liver. Further investigation is ongoing to determine whether changes observed at mRNA levels impacts protein expression and /or function of select transporters.