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Objective@#To investigate GATA3 expression and the regulatory mechanism of m6A modification in the re- sponse of alveolar epithelial cells to radiation, and to provide a new therapeutic target for radiation-induced lung injury based on its pathogenesis.@*Methods@#Human lung epithelial cell line (A549) and mouse lung epithelial cell line (MLE-12) were exposed to X-ray irradiation with a single dose of 10 Gy (dose rate 1 Gy/min) and 6 Gy (dose rate 0.75 Gy/min), respect- ively. The expression of VIRMA gene (RNA methylase) was inhibited by lipofection of A549 cells and MLE-12 cells with shRNA-VIRMA plasmid and siRNA-VIRMA interfering fragment, respectively. Quantification of m6A RNA methylation was performed by colorimetry. Changes in the expression of mRNAs of VIRMA, GATA3, and epithelial-mesenchymal transition (EMT) markers in irradiated A549 and MLE-12 cells were determined by qRT-PCR. Changes in the expression of VIRMA, GATA3, and EMT marker proteins in irradiated A549 and MLE-12 cells were determined by Western blot.@*Results@#Radiation up-regulated the expression of methylase VIRMA in A549 and MLE-12 cells, which in turn enhanced the m6A of total RNA and the expression of GATA3 gene and protein, resulting in EMT. Furthermore, in A549 and MLE-12 cells, interference of the VIRMA gene significantly reduced the expression of GATA3 gene and protein and the expression of EMT-related molecules.@*Conclusion @#Radiation induces m6A modification in alveolar epithelial cells, which up-regu- lates the expression of GATA3 gene and induces EMT, thus playing an important role in the process of radiation-induced lung injury.
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The biological effects of low-dose radiation (LDR) are still a research hotspot in the field of radiobiology. As research deepens on LDR-induced biological effects and the mechanisms, growing evidence shows that LDR produces distinct biological effects from high-dose radiation, which questions the linear non-threshold model. This article reviews LDR-induced bystander effect, hormesis, adaptive response, and hyper-radiosensitivity, as well as the mechanisms, in order to provide a reference for the transformation of basic research on LDR-related biological effects to clinical application.
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N 6-methyladenosine (m 6A) is the most abundant RNA base modification in mammals, especially in eukaryotic messenger RNA (mRNA). N 6-methyladenosine modification can regulate RNA splicing, translocation, stability and ultimately affect protein synthesis. m 6A modification is catalyzed by RNA writers, reduced by erasers and also be recognized by readers. Abnormal changes ofm 6A levels are closely related to tumor occurrence and development, including proliferation, growth, invasion and metastasis. In the process of tumor radiotherapy, m 6A modification affects the efficacy of radiotherapy by affecting DNA damage, tumor stem cell generation and tumor cell radiation sensitivity. This article reviews the role of m 6A-modified epigenetic regulation in malignant tumors and the research progress of its mechanism in tumor radiotherapy, in order to provide new ideas for the development of clinical tumor molecular targeted therapies and radiosensitizers.
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Objective To investigate the effect of neuropilin-1 (NRP1) on radiation-induced epithelial-mesenchymal transition (EMT) by measuring the expressions of EMT-related transcription factors in the irradiated cells with different levels of NRP 1.Methods Human lung type Ⅱ epithelial cells (A549) were transfected with NRP1 over-expression lentiviral vector and NRP1 inhibition vector to construct two cell models of NRP1high-A549 and NRP1low-A549.A NRP1 knock-down cell model was also constructed by transferring siNRP1 into normal mouse lung epithelial MLE-12 cells that was validated at both protein and mRNA levels.A single dose of 10 Gy X-ray was delivered to these cell models,then total protein and RNA were extracted at 0,12,24 and 48 h after irradiation.The expressions of EMT-related transcription factors (Twist and ZEB1) and EMT markers (β3-catenin,N-cadherin,and Vimentin) in each cell model were detected by Western blot and qPCR.Results After 10 Gy irradiation,the expressions of NRP1 mRNA and protein were significantly increased in A549 and MLE-12 cells.The expressions of the mesenchymal markers (Vimentin and N-cadherin) and the transcription factors of ZEB1 and Twist were also significantly increased (A549:t=2.917,7.361,4.852,9.278,P＜0.01;MLE-12:t=9.652,31.357,30.985,17.266,P ＜0.01).The expressions of Vimentin and N-cadherin were significantly decreased in NRP1low-A549 (t =10.077,15.707,P ＜ 0.01) and siNRP1-MLE-12 cells (t =5.745,P ＜ 0.01),but the expression of epithelial marker (β3-catenin) was significantly increased in these cells.The expressions of N-Cadherin and Vimentin were significantly elevated (t =16.055,5.560,P ＜ 0.01),while β-catenin decreased significantly in NRP1high-A549 cells.After irradiation,the transcription factor of Twist in NRP1low-A549 group was significantly decreased (t=3.987,P＜0.01),while the transcription factors of ZEB1 and Twist in the NRP1high-A549 group increased in a time-dependent manner (t =11.289,2.903,P＜0.01).After irradiation,the transcription factor of ZEB1 decreased significantly in siNRP1-MLE-12 cells (t=13.449,P＜0.01),and the protein expressions of ZEB1 and Twist in siNRP1-MLE-12 cells were lower than those of control group in a time-dependent manner.Conclusions NRP1 promotes radiation-induced EMT in human and mouse epithelial cells through up-regulation of transcription factors of ZEB1 and Twist.
