Figure 4.

Diminished survival of MM cell lines exposed in vitro to GSK1120212 and NVP‐BEZ235 individually, or as a combination includes evidence of apoptosis, cell cycle arrest, as well as altered cyclins and Bcl‐2 family cell survival regulatory proteins. (A) Representative bright field contrast images of cultured M5 cells treated with GSK1120212 (G), NVP‐BEZ235 (N), or combination of the two agents (C), or DMSO control (D) for 48 h revealed varied cell densities. (B) Green fluorescence microscopy revealed cells positive for active caspase 3/7 in GSK1120212 (G) or combination‐treated cells (C), indicative of apoptosis. (C) Percentages of apoptotic cells assessed using fluorescent microscopy are plotted for each MM cell line exposed to (G) and (N), or the two agent combination (C). Differences significant from DMSO (D) control (*P < 0.05) or (**P < 0.005) are indicated. (D) Treated cells were analyzed by Western blot for the expression level of Bcl‐2 cell survival regulatory family member proteins, as well as cyclin D1, cyclin E, and p‐Rb, which are important for progression through G₁ cell cycle phase. MM cells exposed to both inhibitors revealed synergy contributing to the diminished survival, compared to single‐drug therapy. Blots of cell lysates were prepared from cells treated for 48 h.