Abstract
Reactive oxygen species (ROS) have been proven to be important activators for various cellular activities, including cell differentiation. Several reports showed the necessity of ROS during cell differentiation of the megakaryocytic (MK) lineage. In this study, we employed near ultraviolet (near-UV) irradiation to generate endogenous oxidative stress in an MK differentiation process of K562 cells with phorbol 12-myristate 13-acetate (PMA) induction. A significant increase in the intracellular ROS level was detected on day 1 after near-UV irradiation. In the initial stage of differentiation, a shifted fraction of G1 and G2 phase cells was obtained using near-UV irradiation, giving an increased percentage of G2 phase cells (up from 31.1 to 68.7%). The near-UV irradiation-induced upregulation of the p21 gene, which is a cell cycle inhibitor, suggested that the G2 phase cells were prevented from undergoing cell division. It was found that the percentage of high ploidy (8N and 16N) cells was enhanced significantly at the later stage of the K562 cell culture with near-UV irradiation. Moreover, time-lapse analysis showed that near-UV irradiation encouraged the expression of CD41, a specific surface marker of megakaryocytes. This is the first report that the elevated oxidative stress through the near-UV irradiation promoted the MK differentiation of PMA-induced K562 cells.
Highlights
Aerobic metabolisms constantly produce a small quantity of reactive oxygen species (ROS), such as superoxide (O2-), hydrogen peroxide (H2O2), and hypochlorous acid (HOCl) [1]
We reported that oxidative stress through H2O2 administration enhanced MK maturation in cells of K562, a human myelogenous cell line [7]
K562 cells have been extensively used as a model in the study of MK differentiation, which can be achieved by exposure to phorbol 12-myristate 13-acetate (PMA) [8,9,10,11]
Summary
Aerobic metabolisms constantly produce a small quantity of reactive oxygen species (ROS), such as superoxide (O2-), hydrogen peroxide (H2O2), and hypochlorous acid (HOCl) [1]. The fluorescence intensity of oxidized reagent from nonirradiated cells without PMA induction was used to calculate the relative value of the ROS content. Real-time PCR analysis Irradiated or non-irradiated cells were cultured in the presence or absence of PMA.
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