Figure 4.

Cellular effects of inhibition of IGF-IR in MCL. PPP induced concentration-dependent decreases in the viability of MCL cell lines. At 24 h, excluding the 0.2 μM concentration of PPP in JeKo-1, and the 0.2 and 0.4 μM concentrations in Mino, all other concentrations induced statistically significant decreases in cell viability compared with untreated cells (P<0.01). At 48 h, PPP induced significant decreases in the viability of JeKo-1 and Mino cells (P<0.001 for all concentrations). In SP-53 cells, the decrease became statistically significant at 1.5 and 2.0 μM concentrations (P<0.5 and P<0.01, respectively), which was probably because of the greater variability of the response of this cell line to the lower concentrations of PPP (A). PPP also caused a concentration-dependent increase in apoptotic cells in MCL cell lines at 24 h, an effect which became more pronounced at 48 h (B). In addition, treatment with PPP was associated with G2/M-phase cell cycle arrest that became more significant with increasing concentrations of PPP (C). Figure 4. Compared with SP-53, the effects of PPP were generally more evident in Mino and JeKo-1 cell lines. The results are shown as means±SD (*P<0.05; ^†P<0.01; ¶: P<0.001; ^§P<0.0001 versus control cells). Morphological features consistent with apoptosis (black arrowheads) including cell shrinkage, nuclear condensation, and cytoplasmic vacuolization were seen after treatment with PPP (D). Also, atypical mitotic figures (red arrowheads) consistent with G2/M-phase cell cycle arrest were associated with treatment with PPP (D). PPP also decreased MCL cell proliferation in time- and concentration-dependent fashions (*:P<0.05; †: P<0.01; ¶: P<0.001; §: P<0.0001 versus control cells) (E). At 48 h, rituximab induced a significant decrease in the viability of JeKo-1 cells. However, the effect of PPP was more pronounced. Combined treatment with PPP and rituximab induced a marked decrease in the viability of these cells (*P<0.01 versus control and PPP + rituximab; ^†P<0.001 versus control and rituximab; ^¶P<0.01 versus PPP + rituximab; ^§P<0.001 versus control) (F, upper panel). At 24 h, treatment of JeKo-1 cells with rituximab alone did not induce a significant increase in apoptotic cells. In contrast, PPP induced a significant increase in apoptotic cells compared with control and cells treated with rituximab alone. Furthermore, combined treatment with PPP and rituximab further enhanced apoptotic cell death (*P<0.01 versus control, rituximab, and PPP + rituximab; ^†P<0.001 versus control and rituximab) (F, lower panel). PPP induced a concentration-dependent decrease in the viability and proliferation of primary MCL cells that expressed IGF-IR. In contrast, PPP had minimal effects on MCL cells that were negative for IGF-IR (patients are shown in Table 1) (G).