Fig. 2

Activity of trabectedin in MM cells. a Representative dot plots of dose-dependent apoptosis increase in U266 and MM1S cells after dose escalation of trabectedin evaluated with annexin-V/7aad assay. In the lower left panel are represented the results of trabectedin activity on 12 MM cell lines at different time points. Each point represents the average result of at least 3 replicates. All cell lines (except for LR7) were very sensitive to trabectedin, with an IC50 at 72 h ranging from 0.5 to 2.5 Nm (%viable cells at the IC50 point significantly lower as compared with the control point, p < 0.01 for all cell lines). b Trabectedin activity on primary MM cells derived from 3 different patients, exposed to 2.5 nM of the drugs. After 24 h, we observed over 50% apoptosis evaluated with annexin-V/7aad assay. c Western blots reporting the expression of XPF and ERCC1 proteins in all the cell lines evaluated for sensibility to trabectedin treatment. On the right, evaluation of differences in protein expression after quantization, normalization and removal of outliers through ROUT test (Q = 1%). d A representative immunohistochemistry images of 3D model of U266 MM cells (in the absence or presence of macrophages) growth in matrigel-based spheroids, demonstrating the reduction of proliferation niches in trabectedin treated cells respect to control. The right dot plots showed the pro-apoptotic effects of trabectedin both in presence and in absence of macrophages (representative experiment of three) and the respective histograms showing the mean of three different experiments. *p < 0.05