Effect of miR-128 in DNA damage of HL-60 acute myeloid leukemia cells.

miR-128 has been associated with cancer, particularly with leukemia. In particular, this miR has been described, together with other miRs, to allow the discrimination between AML (acute myeloid leukemia) and ALL (acute lymphoblastic leukemia). In addition, miR-128 is included in miR signatures which not only allow characterizing a particular subtype of AML but are also associated with worse clinical outcome in a subgroup of patients with high-risk molecular features of AML. Nevertheless, all the published studies are based on data from expression arrays and no functional studies have been performed. Therefore, in order to further understand the role of miR-128 in AML cells and in their response to some chemotherapy, overexpression of miR-128 was achieved with miR-mimics in an AML cell line (HL-60). This resulted in decreased cellular viability and increased sensitization to both etoposide and doxorubicin. Overexpression of miR-128 increased programmed cell death but had no effect on cell cycle profile, 1 apoptosis or autophagy, as no alterations were observed in the protein levels of PARP, pro-caspase-3, Vps34, Beclin-1 or LC3-II. In addition, miR-128 overexpression increased the levels of DNA damage, as could be concluded by an increase in the comet's tail intensity in the comet assay, an increase in the number of DNA repair foci stained with either γ-H2AX or 53BP1 proteins, and an increase in the levels of these two proteins (observed by Western blot). To the best of our knowledge, this is the first association of miR-128 with DNA damage in a leukemia context.