Inhibition by curcumin. (A) Curcumin inhibits TNF-induced adhesion of multiple myeloma cells to bone marrow stromal cells (BMSCs). BMSCs were incubated with curcumin (0, 1, and 10 μM) for 12 hours followed by treatment with TNF (5 ng/mL) for 2 hours. After replacing the culture media, tritiated thymidine-labeled U266 cells were added and, after 1 hour, the percentage of adherent cells evaluated. (B) Curcumin inhibits constitutive and MM cell–induced IL-6 production from BMSCs. BMSCs and U266 cells were cultured alone or together in the presence or absence of curcumin (1 to 10 μM). After 24 hours, culture supernatants were collected and measured IL-6 by ELISA. Values represent the mean ± SD of triplicate cultures.