Objective:To explore the mechanism of miR-205-5p/E2F1 signal axis in regulating the glioma U251, U87 radiotherapy resistance.Methods:X-ray gradual ascending and intermittent induction method was used to irradiate the glioma U251 cells to establish U251/TR, U87/TR radiation-resistant cell lines. Then, the morphology, migration, invasion and proliferation abilities of cells (U251/TR, U87/TR radiation-resistant cells and U251, U87 radiation-sensitive cells) were analyzed. Luciferase gene detection system and point mutation technique were employed to analyze the mechanism of miR-205-5p and E2F1 gene activity on U251 and U87 radiation-resistant cell lines.Results:Compared with the radiation-sensitive U251 cells, the radiation-resistant cells U251/TR, U87/TR showed increased proliferation activity, enhanced migration and invasion abilities and decreased apoptosis under X-ray irradiation. miR-205-5p mimics transfection could down-regulate the expression of E2F1 factor in U251/TR cells, inhibit cell proliferation, invasion and migration and increase the radiosensitivity of U251/TR cells. miR-205-5p mimics transfection combined with with E2F1 down-regulation exerted anti-tumor effect and decreased cell tolerance by suppressing the Wnt/β-catenin signaling pathway activity.Conclusions:The glioma radiation-resistant cell line U251/TR, U87/TR can be established by X-ray gradual ascending and intermittent induction method. The miR-205-5p/E2F1 signal axis exerts tumor-suppressing effect through the classical Wnt/β-catenin signaling pathway, which can be used as an therapeutic target to increase the radiosensitivity of glioma.

ObjectiveTo investigate a cluster epidemic of coronavirus disease 2019 （COVID-19） infections in a school in Longchuan County， Yunnan Province， and further guide the prevention and control of COVID-19 in the border area. MethodsAccording to the Protocol on Prevention and Control of Novel Coronavirus Pneumonia （8th Edition）， an epidemiological investigation was performed on all COVID-19 cases to collect the information on demographics， onset， diagnosis and treatment， prognosis， and epidemiological history. Close contacts were also tracked to determine the transmission chains. ResultsIn this cluster epidemic， a total of 37 COVID-19 cases were identified， including 32 females and 5 males aged from 13 to 25 years， who were 35 students and 2 teachers. The student cases were found in four classes of two grades. Furthermore， gene sequencing showed that all cases had been infected with delta variants， belonging to the same transmission chain that was not related to the previous epidemics in Dehong Prefecture. In additionally， a total of 2 127 close contacts were found. After 21 days of centralized quarantine for medical observation， all close contacts tested negative for SARS-CoV-2. In the COVID-19 cases， only one case remained positive for SARS-CoV-2， while the other 36 cases were successfully treated and became negative. ConclusionThis school cluster is caused by the border villagers who contacted the water polluted with SARS-CoV-2. It warrants more strict management of students from border villages and their belongings to prevent similar epidemics in school settings.