Combined effect of GSI and chemotherapeutics on MM cells. (A) H929 cells were cultured overnight on a BMS monolayer established from 2 different donors with or without 5 μM GSI. Doxorubicin (Dox, 0.25 μM) was then added to the cultures where indicated and cells were cultured for an additional 24 hours. Apoptosis of myeloma cells was evaluated by annexin-FITC/DAPI staining using an LSR II flow cytometer. (B) GSI (5 mg/kg) was injected intraperitoneally into SCID/NOD mice (2 mice per time point). Blood was collected at different time points, and the concentration of GSI was determined in sera as described in “Measurement of GST in serum.” Control indicates mice not treated with the compound. (C,D) RPMI-8226 (C) or H929 (D) tumors were established subcutaneously in SCID/NOD mice. Mice were split into 4 groups (5 mice per group) with equal size tumors and treated with GSI, doxorubicin, or a combination thereof. Tumor growth was monitored. Four experiments with similar results were performed; 2 of them are shown. Mean plus or minus SD values are shown. (E-G) The SCID-hu model was established as described in “SCID-hu mouse model.” Tumor growth was monitored by measuring the level of human paraprotein in mouse sera. Approximately 4 weeks after tumor injection, mice were split into 4 groups (3–4 mice per group) with equal average level of free lambda light chain in the sera. Mice were treated with GSI, doxorubicin, melphalan, or a combination of GSI with chemotherapeutic drug (either doxorubicin or melphalan) for 14 days. Please note the different scale for control group (E) and treated groups of mice (F,G). Mice were killed 1 week after the end of the treatment. Mean plus or minus SD values are shown.