MiR-34a-5p Has Been Involved In Damage And Repair Of Vascular Endothelia Caused By β Ray Via C-Myc And STAG-2 Pathway

Background: Vascular homeostasis is important to our health. Damages to vascular endothelial cells lead to many diseases including coronary heart disease. Radionuclides irradiation which can produce β rays, is an important means of clinical treatment of malignancies, but the side effects caused by β rays cannot been ignored. We hypothesized that the side effects caused by β ray was related to the injury of vascular endothelial, which lead to the imbalance of blood vessel homeostasis, but the specific mechanisms have not been reported both at home and abroad. Therefore, we set up a model by tritiated water(HTO) to explore the mechanism of β-ray injury on vascular endothelium.Methods: After HTO was added into HUVEC cell suspension within three consecutive days, Cell Counting Kit-8 was used to evaluate the cell proliferation capacity and Trypan blue exclusion was used to measure the cell viability in each day. The expression of mi R-34a-5p was detected by QT-PCR within 12 H in HTO group at6 different time points. Comet assay and γH2AX Immunofluorescence staining were used to measure DNA single-strand breaks or DNA double-strand breaks in HTO and control group at 4 time points. Mi R-34a-5p mimics, mi R-34a-5p inhibitor and their controls were transfected into HUVEC cells by using lipofectamine 2000. The 4groups were irradiated by HTO. The same methods were used to measure the cell proliferation capacity, cell viability, DNA single-strand breaks and DNA double-strand breaks in those 4 groups at same condition as before. At last, we use RNA extraction and reverse transcriptase polymerase chain reaction to measure the expression of c-Myc and STAG-2 in 6 groups as mentioned above at 0.5h and 2h.Results: In HTO group, the cell proliferation capacity and viability were significantly lower within 3 days as compare with the control group. Mi R-34a-5p was changing within12 H after HTO irradiated HUVEC cell. According to the dynamic expression of mi R-34a-5p in HUVEC cell within 24 H, we selected the highest time point, the lowest time point and the 2 time points of acute phase, namely 0h, 0.5h, 2h and 4h to observe the function of mi R-34a-5p in cell which irradiated by HTO. The DNA single-strand breaks or DNA double-strand breaks were higher in HTO group than the control group at0.5h, 2h and 4h. Also, the trend of the two results at 0.5h, 2h and 4h are consistent. After HTO irradiated HUVEC cell, we found that over expression of mi R-34a-5p lead to DNA damage higher than suppression of mi R-34a-5p and the proliferation capacity and viability was lower than suppression of mi R-34a-5p at 0.5h, 2h and 4h. We also found that over expression of mi R-34a-5p can lead to the expression of c-Myc and STAG-2 lower than suppression of mi R-34a-5p at 0.5h and 2h time points.Conclusion: In summary, mi R-34a-5p regulated the expression of c-Myc and STAG-2 gene to participate in the process of cell damage caused by β-rays.Our study illust rated the damage mechanisms of vascular endothelial cells caused by β rays from the level of molecular. Apart from this, the study also has shown a completely new sight of preventing and treating the clinical side effects of radionuclide therapy.