The Oncopig Cancer Model (OCM) is a unique transgenic porcine model that develops inducible site and cell specific tumors, and permits in vitro pharmacologic screening using cell lines with the ability to translate promising strategies to in vivo using solid organ tumors. To validate OCM utility for in vitro drug screening, this study tested the hypothesis that OCM and human hepatocellular carcinoma (HCC) cell lines exhibit similar expression of drug metabolizing enzymes (DMEs) and comparable dose response to standard chemotherapies.
Responses to cytostatic (sorafenib) and cytotoxic (doxorubicin, DOX) HCC chemotherapies were compared between OCM (n=3) and human HCC (HepG2, Huh7, Hep3B) cell lines using MTT assays in triplicate. Expression of DMEs involved in sorafenib and DOX uptake, metabolism, and export (human: CYP3A4, UGT1A1, UGT1A6, ABCB1, OCT1, and CBR1; porcine homologs: CYP3A22, CYP3A29, CYP3A39, CYP3A46, UGT1A1, UGT1A6, ABCB1, OCT1, and CBR1) was determined by quantitative PCR (qPCR). Results were normalized to GAPDH housekeeping values and statistically compared.
OCM and human HCC cell lines displayed similar chemotherapy sensitivities when exposed to comparable, clinically relevant concentrations for 72 hours. Sorafenib had cytostatic effect at 2-10 µM in all OCM and human HCC cells lines, consistent with 3-15 µM clinical systemic therapeutic levels. DOX, administered at 1-5 µM for locoregional therapy, had comparable half maximal inhibitory concentrations for OCM (~0.1 µM) and human HCC (0.2-0.4 µM). Sorafenib uptake transporter (SLC22A1; OCT1), phase 1 metabolism (CYP3A4; CYP3A22, CYP3A29, CYP3A39, and CYP3A46), phase 2 metabolism (UGT1A9; UGT1A1, UGT1A6), and efflux (ABCB1) gene expression was similar between OCM and human HCC (P>0.05). OCM HCC showed higher DOX phase 1 metabolism (CBR1) gene expression compared to human HCC (2.2 vs. 1.5, P=0.028), but DOX efflux (ABCB1) gene expression was similar (P>0.05).
OCM HCC shows similar drug response and DME expression levels compared to human HCC, indicating that the OCM represents a valuable tool for screening promising chemotherapy agents.