Abstract 1191: The dopamine (DA) D3receptor antagonists (PG01037, NGB2904, SB-277011A, and U99194) significantly attenuate ABCG2-mediated multidrug resistance

ATP-binding family G2 (ABCG2) transporters are known to produce multidrug resistance (MDR) and limit successful cancer chemotherapy. Using molecular modeling, we obtained data indicating that highly potent and selective dopamine (DA) D3 receptor antagonists had significant docking scores for the active site of the ABCG2 transporter. In this in vitro study, we determined the effect of the D3 receptor antagonists (PG01037, NGB2904, SB-277011A, and U99194) on MDR resulting from the overexpression of ABCG2 transporters. The D3 receptor antagonists alone did not significantly affect the viability of HEK293/ABCG2, H460/MX-20, S1-M1-80 or A549-MX-10 cells, which overexpress ABCG2 transporters. However, the D3 receptor antagonists (PG01037, NGB2904, SB-277011A, and U99194) significantly increased the efficacy of the anticancer drugs mitoxantrone and doxorubicin in the above mentioned cell lines. Efflux studies indicated that both PG01037 and NGB2904 significantly decreased the efflux of rhodamine 123 from H460-MX20 cells. Interestingly, PG01037 and NGB2904 significantly decreased the expression levels of the ABCG2 protein levels as shown by immunocytochemical and Western blot analysis. This suggests that D3 antagonists inhibit both function and expression of ABCG2 transporters at relevant non-toxic concentrations. In conclusion, our in vitro results indicate that PG01037, NGB2904, SB-277011A, and U99194 reverse resistance to mitoxantrone and doxorubicin mediated by overexpression of ABCG2 transporters. Further mechanistic and animal studies are warranted to establish the clinical use of D3 receptor antagonists in reversing ABCG2-mediated MDR. Citation Format: Noor Hussein, Haneen Amawi, Charles R. Ashby, Karthikeyan Chandrabose, Roopali Mittal, Ryann Christman, Piyush Trivedi, Amit Tiwari. The dopamine (DA) D3 receptor antagonists (PG01037, NGB2904, SB-277011A, and U99194) significantly attenuate ABCG2-mediated multidrug resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1191. doi:10.1158/1538-7445.AM2017-1191