Blue light induces ROS mediated apoptosis and degradation of AML1-ETO oncoprotein in Kasumi-1 cells.

Light-emitting diode (LED)-based therapies, particularly blue LEDs with wavelengths of 400-500 nm, have shown beneficial results in several cancers, including melanoma, lymphoid cells, and skin tumors. In this study, the cell viability and apoptosis of Kasumi-1 cells treated by blue light (BL) irradiation have been explored. Firstly, BL can specially inhibit the proliferation and promote the apoptosis of Kasumi-1 cells. Furthermore, the apoptosis was triggered by the production of reactive oxygen species and the decline of mitochondrial membrane potential which was regulated by the ratio of Bcl-2(Bcl-xL)/Bax; BL caused the cells' final apoptosis accompanied with the increased cleavage of caspase-3 and poly-ADP-ribose polymerase. Finally, BL induced the degradation of AML1-ETO dependent on the activation of caspase-3. These results are helpful for establishing a low toxicity and high efficiency strategy of BL irradiation for clinical treatment of Kasumi-1 cells.

PML-RARA fusion transcripts in irradiated and normal hematopoietic cells.

It is believed that two important factors in the genesis of reciprocal chromosomal translocations in malignant cells are the physical proximity of the involved regions and local structural features of the chromatin fiber that make them more susceptible to breakage and rearrangement. In this work we sought to investigate whether PML-RARA fusion transcripts, characteristic of acute promyelocytic leukemia (APL), could be induced by a clastogenic agent in cells known to have, a priori, a favorable spatial distribution of these genes. A lymphoid-cell line, lacking the t(15;17) but having the PML and RARA genes in close proximity in specific phases of the cell cycle, was irradiated with 10 Gy of (60)Co, and the incidence of PML-RARA transcripts was analyzed by a highly sensitive PCR assay. Despite gene proximity, typical PML-RARA transcripts were only rarely detected in irradiated cells. The same phenomenon was observed at similar frequency in control non-irradiated cells. These findings made us investigate whether such transcripts could also be detected in peripheral blood cells from normal individuals. PML-RARA transcripts were observed at low frequencies in isolated lymphoid and granulocytic cell populations, with similar incidence in both cell types. The data thus indicate that the PML and RARA genes are not particularly susceptible to the clastogenic effects of gamma-irradiation, and that, similar to what has been reported for other chromosomal translocations, transcriptionally active PML-RARA rearrangements can be generated in normal hematopoietic cells of different lineages without apparent oncogenic consequences.