Objective:To investigate the effect of ubiquitin binding enzyme 2T (UBE2T) on the radiosensitivity of lung adenocarcinoma and unravel its possible mechanism.Methods:A total of 45 patients pathologically diagnosed with different stages of lung adenocarcinoma and treated with radiotherapy in the Second Affiliated Hospital of Zunyi Medical University from March, 2019 to December, 2021 were enrolled, and the efficacy was evaluated according to response evaluation criteria in solid tumors (RECIST1.1). All patients were divided into radiosensitive group ( n=25) and radioresistant group ( n=20). Radiosensitive group was complete remission (CR)+partial remission (PR), and radioresistant group was stable disease (SD) + progression disease (PD). Immunohistochemistry (IHC) was used to calculate the score based on the staining intensity and the number of positive cells. Chi-square test was combined to analyze the correlation between the expression level of UBE2T in paraffin specimens of lung adenocarcinoma patients and the radiosensitivity of patients. Lentivirus UBE2T-interfered (UBE2Tsh) A549 and UBE2T-overexpressed SPC-A-1 lung adenocarcinoma cells and their respective controls were constructed for irradiation and colony formation assay. The survivor fraction curve was fitted by single-hit multi-target model. The DNA double-strand break (DSB) marker γH2AX foci were detected by immunofluorescence (IF). The expression levels of UBE2T, γH 2AX and Rad51 proteins were detected by Western blot. Cell cycle and apoptosis rate of A549 were determined by flow cytometry. Binary variables were statistically analyzed by Fisher's exact probability method and measurement data were assessed by t-test. Results:High-expression level of UBE2T was correlated with the radiosensitivity of lung adenocarcinoma patients ( P<0.05). UBE2Tsh improved the radiosensitivity of A549 lung adenocarcinoma cells, and the sensitizing enhancement ratio (SER) was 1.795. UBE2T overexpression decreased the radiosensitivity of SPC-A-1 lung adenocarcinoma cells with an SER of 0.293. γH2AX foci number per cell were significantly increased in UBE2Tsh A549 cells after irradiation ( P<0.01) . Compared with the control group, the expression level of γH2AX protein was up-regulated ( P<0.01)and that of Rad51 protein was down-regulated in UBE2Tsh A549 cells after radiation ( P<0.001). Compared with the control group, the expression level of γH2AX protein was down-regulated ( P<0.05) and that of Rad51 protein was up-regulated in UBE2T overexpressed SPC-A-1 cells ( P<0.001). The proportion of UBE2Tsh A549 cells in G 2 phase was decreased ( P<0.01) and cell apoptosis was increased ( P<0.001). Conclusions:UBE2T might promote the radioresistance of lung adenocarcinoma cells by enhancing DNA DSB repair induced by radiotherapy, inducing cell cycle G 2 phase arrest, and reducing cell apoptosis.

Objective To investigate the effects of different concentrations of PPF on oxidative stress and apoptosis of PD model cells induced by MPP+.Methods The human neuroblastoma cell SH-SY5Y was induced by 1 mM MPP+ to establish PD cell model.In PPF treatment group,SH-SY5Y cells were stimulated with 10,20,40 and 80 μM PPF for 4 h before MPP+ induction.Cell counting kit-8(CCK-8)was performed to evaluate cell proliferation activity.H2DCF-DA fluorescent probe was used to detect ROS in cells.The levels of MDA and NADPH oxidase were analyzed by the kit.Western blot examined the protein expression of cytochrome c in mitochondria and cytoplasm,as well as the relative expression of Bcl-2,Bax and cleaved caspase-3 in SH-SY5Y cells.Apoptosis rate was analyzed by flow cytometry.Results MPP+ significantly inhibited the proliferation of SH-SY5Y cells(P<0.001),promoted the level of ROS(P<0.001),MDA(P<0.001),NADPH oxidase(P<0.01),cytochrome c in cytoplasm(P<0.01)and induced apoptosis(P<0.001)and the relative expression of pro-apoptosis protein Bax and cleaved caspase-3(P<0.01),reduced cytochrome c protein in mitochondria(P<0.01)and the relative expression of anti-apoptosis protein(P<0.01).PPF pretreatment alleviated the proliferation inhibition,oxidative stress and apoptosis promotion of SH-SY5Y cells induced by MPP+(P<0.001),and the effects of 40 μM and 80 μM on cells were more significant.Conclusion PPF pretreatment can alleviate the oxidative stress of SH-SY5Y cells induced by MMP+ and reduce apoptosis rate.