Figure 4. Table 1.

(A) TCH-013 inhibits cell growth in bortezomib (BTZ) resistant THP-1 cells that overexpress mutated β5 subunits. Parental and BTZ resistant THP-1 cell lines were treated with TCH-013 continuously for 72 hours and viability was measured using a MTS dye conversion assay. Resistance factor is an expression of the GI₅₀ of the BTZ resistant THP-1 cell line divided by the CC₅₀ of the parental THP-1 cell line. (B) In vitro viability testing results for leukemia, myeloma and supportive primary cell lines. (C) Murine bone marrow derived macrophages (mononuclear cells) were cultured under osteogenic differentiation conditions (50ng/ml M-CSF and 50ng/ml RANKL) in the continual presence of vehicle or indicated concentrations of TCH-013. Formation of multinucleated osteoclasts is visualized by tartrate-resistant acid phosphatase (TRAP) staining on day 6. At concentrations similar to those required to exert tumor cells cytotoxicity, TCH-013 inhibited the formation of multinucleated osteoclasts.(D) Survival of RPMI8226 cells alone(left) or in the presence of human BMSCs(right) as measured by Luciferase Activity(D, top panels) and MTT Assay(D, bottom panels), cells were incubated with various concentrations of TCH-013 ranging from 1.25μM to 20μM. The IC₅₀ was determined by Prism(Graphpad).