Effects And Mechanism Of 280nm LED- UV On The HL-60 Cells

ObjectiveTo observe the effect of280nm Light Emitting Diode-Ultraviolet(LED-UV) on human leukemia HL-60cells proliferation and explore its mechanism.MethodsThe HL-60cells of logarithmic growth phase were divided into five groups(control group A and experimental groups B-E). Cells of different groups were irradiated by280nm LED-UV with different doses respectively:OJ/m2、8J/m2、15J/m2、30J/m2、60J/m2. After irradiation, all cells were cultured in IMDM culture containing10%fetal bovine serum and incubated for2hours at37℃,5%CO2and saturated humidity condition. We applied an invert microscope to observe cell growth and morphology, CCK-8assay to measure the inhibition of cell proliferation, quantitative PCR to detect Bcl-2expression, Annexin V-FITC/PI double staining and PI staining combined with flow cytometric analysis to test apoptosis and cell cycle distribution respectively.Results1. HL-60cell growth and morphology:Cells in control group were complete, round and translucent, which arranged in an orderly manner and showed high growth density. While cells in experimental groups shrank and arranged in disorder, the brightness and density dropped as the dose of LED-UV increased. There was plenty of cell debris in group E.2. The inhibition of HL-60cell proliferation: The inhibition rate among experimental groups had significant difference (F=1297.68, P<0.01), which gradually increased as the dose of LED-UV increased, pairwise comparisons had significant differences (all P<0.01).3. The expression of Bcl-2gene:Bcl-2expression among experimental groups had significant difference (F=54.34, P<0.01), which gradually decreased as the dose of LED-UV increased among groups B-D, pairwise comparisons had significant differences (all P<0.01). While the expression in group E was higher than that in group D(P<0.01).4. HL-60cell apoptosis:The apoptosis rate among five groups had significant difference (F=293.50, P<0.01), which gradually increased as the dose of LED-UV increased among groups A-D, pairwise comparisons had significant differences (all P <0.01). While the apoptosis rate in group E was lower than that in group D (P<0.01).5. HL-60cell cycle distribution: The percentage of G0/G1cells among five groups had significant difference (F=173.44, P<0.01), which gradually increased as the dose of LED-UV increased among groups A-D, pairwise comparisons had significant differences (all P<0.05). While the percentage in group E was lower than that in group D (P<0.01).Conclusions1.280nm LED-UV could inhibit the expression of Bcl-2gene. Within dose of8-30J/m2, the inhibitory effect was in a dose-dependent manner. The inhibition was strongest at the dose of30J/m2while weaker at the dose of60J/m2.2.280nm LED-UV could induce cell apoptosis. Within dose of0-30J/m2, the apoptosis rate was in a dose-dependent manner. The apoptosis was strongest at the dose of30J/m2while weaker at the dose of60J/m2.3.280nm LED-UV could make HL-60cell cycle arrest in G0/G1phase. Within dose of0-30J/m2, the blocking effect was in a dose-dependent manner. The arrest was strongest at the dose of30J/m2while weaker at the dose of60J/m2.4.280nm LED-UV could inhibit the proliferation of HL-60cells in a dose-dependent manner. Within dose of0-30J/m2, the main effect was apoptosis, whose mechanism included the inhibition of Bcl-2expression and cell cycle arrest in G0/G1phase. At the dose of60J/m2, the main effect was necrosis.