Curcumin increases the sensitivity of NF1 associated MPNST cells to TRAIL.

<p>A, 1507.2 cells were pretreated with 10 µM of the indicated phytochemical and subsequently treated with 100 ng/ml TRAIL for 20 h. The calculated additive effect (phytochemical and TRAIL) was determined and compared with the actually observed effect. B, FACS analysis of 1507.2 cells treated with curcumin alone or in combination with TRAIL. C, 1507.2 cells were preincubated with DMSO or curcumin and subsequently treated with 100 ng/ml TRAIL or left untreated. Immunoblots show levels of caspase 8, caspase 9, PARP and their corresponding cleavage fragments. D, S462, ST88-14 and NFS-1 cells were pretreated with DMSO or 10 µM curcumin and subsequently treated with 100 ng/ml TRAIL for 20 h. Viability was analyzed by crystal violet assay. Corresponding immunoblots show PARP and its cleavage fragment. E, Curcumin treatment of NF1 associated MPNST leads to downregulation of anti-apoptotic proteins. 1507.2, S462, ST88-14, NFS-1 cells were treated for 24 h with DMSO, 5 and 10 µM curcumin and analyzed for expression of apoptosis regulating proteins by immunoblotting. BCL-2 expression is only depicted for S462 cells because it was not detectable in 1507.2 and ST88-14 cells. Claspin expression was only detectable in 1507.2 cells. The values below the bands are the relative densities. E, A, B, D, Results are expressed as mean ± s.d. of three independent experiments (n = 3). Asterisks outline values that are different from respective control (* = P<0.05; ** = P<0.01, Student's t-test). The values below the bands are the relative densities.