MiRNA-16-1 Suppresses Mcl-1 and Bcl-2 and Sensitizes Chronic Lymphocytic Leukemia Cells to BH3 Mimetic ABT-199.

Objective: Chronic lymphoid leukemia (CLL) is the most common type of leukemia among adults. Increased levels of Mcl-1 and Bcl-xL is linked to resistance to Bcl-2 inhibitors including ABT-199. In this study, we investigated the effect of miRNA-16-1 on apoptosis and sensitivity of the CLL cells to ABT-199.
Materials and Methods: In this experimental study, the Mcl-1 and Bcl-2 expression were measured using qualitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting. The effect of treatments on cell survival and growth were explored with MTT assay and Trypan blue assay, respectively. The drug interaction was evaluated using combination index analysis. Apoptosis was assessed by ELISA cell death and caspase-3 activity assays.
Results: MiRNA-16-1 markedly inhibited the expression of Mcl-1 and Bcl-2 in a time dependent manner (P<0.05, relative
to blank control). Pretreatment with miRNA-16-1 synergistically suppressed the cell growth and survival and reduced the half-maximal inhibitory concentration (IC50) value of ABT-199. Moreover, miRNA-16-1 markedly augmented the apoptotic effect of ABT-199 in CLL cells (P<0.05).
Conclusion: Our findings propose that miRNA-16-1 act in concert with ABT-199 to exert synergistic anticancer efficacy against CLL, which is attributed to the inhibition of Bcl-2 and Mcl-1. This may propose a promising strategy for CLL resistant patients.