Low-dose ionizing radiation effects on differentiation of HL-60 cells

Abstract

The biological effects of low-dose radiation have attracted attention, but data are currently insufficient to fully understand the beneficial role of the phenomenon. In the present study, we have investigated the effects of low doses of gamma-irradiation alone and in combination with all-trans-retinoic acid (RA) on proliferation, apoptosis and differentiation of the human promyelocytic leukemia HL-60 cells. Changes in cell behavior and protein expression were determined with the use of light and fluorescent microscopy, immunocytochemical and Western blot analysis. Low-dose irradiation with 1–100 cGy caused a dose-dependent inhibition of HL-60 cell proliferation, and induced apoptosis and differentiation to granulocytes with an increase in the number of CD15-positive cells. Pre-irradiation with 1–100 cGy for 24 h before treatment with RA promoted apoptosis but did not impair RA-induced differentiation. Both processes were associated with a decrease in the expression of the proliferating cell nuclear antigen (PCNA), BCL-2, c-MYC, and changes in both cytosolic and nuclear levels of protein tyrosine-phosphorylation as well as protein kinase C alpha or beta isoforms. These results demonstrate the beneficial role of low-dose irradiation in modulating leukemia cell proliferation, differentiation and apoptosis.

Effects of radiation dose on the stemness-related genes expression in colorectal cancer cell line

“…Regarding low-dose irradiation, some studies addressed the preventive effect of low-dose irradiation on CSC induction. Savickiene et al demonstrated that low-dose of gammairradiation (1-100 cGy) caused 25% of HL-60 cells undergoing differentiation, while only 3-5% of these cells underwent spontaneous differentiation (45) . Additionally, Kaushik et al observed that low-dose radiation suppressed EMT and CSC induction in breast cancer cells by inhibiting the Jak1/STAT3 signaling pathway (46) , which are inconsistent with the results of the present study in which all three genes are overexpressed at 0.1 Gy.…”