Background: Multiple myeloma (MM) is a fatal disease characterized by clonal proliferation of plasma cells in the bone marrow. Recently novel therapeutic drugs such as bortezomib and lenalidomide have been improved survival of MM. However, we still need to find out new drugs for treatment MM. Here we performed a high-throughput cell-based screening using a FDA-approved 380 drug library (Selleckchem, USA) to find out sensitizer in combination with bortezomib. Materials and methods: We carried out high-throughput screening using cell counting kit-8 (CCK-8, Dojindo, USA). RPMI8226 MM cells were plated 1x104 cells/well in 96-well assay plates then treated with 0.25 nM bortezomib and combination with 1 uM drug libraries for 48 hours. Analysis was done by four different methods (non-controls-based normalization, median-based activities, Z scores, and B scores). Then we selected 30 high ranking drugs for inhibition of proliferation and albendazole was selected through literature review. To investigate of albendazole effect, we performed cell proliferation assay using 0, 0.1, 1, 10 uM of albendazole and combination with 0, 0.25, 0.5, 1 nM of bortezomib at 24, 48, 72 hr in four MM cell lines (RPMI8226, MM.1S, MM.1R and U266). Inhibitory concentration 50 (IC50) and combination index (CI) calculated by compusyn software (Combosyn, USA). Cell cycle and apoptosis was analyzed by flow cytometry using the PI and Annexin V/7AAD staining kit (BD Biosciences, USA) with 0, 0.1, 1, 10 uM of albendazole at 24, 48, 72 hr in RPMI8226 and MM.1S cells. Results: Total of 180 drugs showed inhibitory effects compared with that of single treatment with bortezomib. High ranking drugs belonged to anthracycline, cytotoxic antibiotic, antihelmintic, target DNA topoisomerase I, II and microtubule function inhibitor. For albendazole, IC50 values in RPMI8226, MM.1S, MM.1R, and U266 were 0.63, 2.78, 7.26, and 5.93 uM, respectively. Peripheral blood mononuclear cells from blood donor separated by ficoll density gradient were treated by albendazole represented IC50 over 9000 uM which implicated high therapeutic index. MM cells of treatment with 1 uM albendazole for 24 hr were induced G2/M phase cell cycle arrest and increased significantly late stages of apoptosis. Finally, combination treatments with albendazole and bortezomib synergistically induced cytotoxicity against MM cell lines. Conclusions: This study showed that albendazole had potent anti-myeloma activities and enhanced the activity of bortezomib. These results indicate that albendazole may have therapeutic potential in multiple myeloma and provide the framework for future studies of albendazole in multiple myeloma.

Citation Format: Min Kyeong Kim, Sunshin Kim, So Jin Park, Hyewon Lee, Tae Sik Kim, So Youn Jung, Hyun Guy Kang, Hyeon-Seok Eom, Kong Sun-Young. High-throughput cell-based screening of drug library identifies albendazole as a sensitizer with combination of bortezomib for treatment multiple myeloma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1702. doi:10.1158/1538-7445.AM2014-1702