Figure 4.

Dinaciclib transforms the p21 to the p16 pathway in a senescence model induced by DOX in MM RPMI-8226 cells. (A) RPMI-8226 cells were treated with DMSO, 100 nM DOX, 5 nM dinaciclib, or DOX and dinaciclib for 24 h. Cells were extracted and proteins were incubated with primary antibodies against p-ATM, ATM, γ-H2AX, p-Chk2, Chk2, p-p53, p53, p21 and p16. GAPDH was used as a loading control. Protein quantification was conducted. (B) RPMI-8226 cells were treated with DMSO, 10 µM KU-55933, 100 nM DOX, or DOX and KU-55933 for 24 h. Cells were extracted and proteins were incubated with primary antibodies against p-ATM, ATM, CDK5. GAPDH was used as a loading control. Protein quantification was conducted. (C) Low-dose of dinaciclib enhanced anti-MM effects mediated by DOX via transformation of the p21-p16 pathways, accelerating senescence rather than apoptosis induced by DOX. Data were obtained from at least three independent experiments. Differences between multiple groups was confirmed using one-way analysis of variance followed by Tukey's post hoc test. *P<0.05 as indicated. MTT, multiple myeloma; DOX, doxorubicin; ATM, ataxia telangiectasia mutated; DOX, doxorubicin; CDK, cyclin-dependent kinase.