AZD1775 and anti-PD-1 antibody synergistically sensitize hepatoma to radiotherapy / 中华医学杂志(英文版)

BACKGROUND@#Radiation (IR)-induced DNA damage triggers cell cycle arrest and has a suppressive effect on the tumor microenvironment (TME). Wee1, a cell cycle regulator, can eliminate G2/M arrest by phosphorylating cyclin-dependent kinase 1 (CDK1). Meanwhile, programed death-1/programed death ligand-1 (PD-1/PDL-1) blockade is closely related to TME. This study aims to investigate the effects and mechanisms of Wee1 inhibitor AZD1775 and anti-PD-1 antibody (anti-PD-1 Ab) on radiosensitization of hepatoma.@*METHODS@#The anti-tumor activity of AZD1775 and IR was determined by 3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide (MTT) assay on human and mouse hepatoma cells HepG2, Hepa1-6, and H22. The anti-hepatoma mechanism of AZD1775 and IR revealed by flow cytometry and Western blot in vitro . A hepatoma subcutaneous xenograft mice model was constructed on Balb/c mice, which were divided into control group, IR group, AZD1775 group, IR + AZD1775 group, IR + anti-PD-1 Ab group, and the IR + AZD1775 + anti-PD-1 Ab group. Cytotoxic CD8 + T cells in TME were analyzed by flow cytometry.@*RESULTS@#Combining IR with AZD1775 synergistically reduced the viability of hepatoma cells in vitro . AZD1775 exhibited antitumor effects by decreasing CDK1 phosphorylation to reverse the IR-induced G2/M arrest and increasing IR-induced DNA damage. AZD1775 treatment also reduced the proportion of PD-1 + /CD8 + T cells in the spleen of hepatoma subcutaneous xenograft mice. Further studies revealed that AZD1775 and anti-PD-1 Ab could enhance the radiosensitivity of hepatoma by enhancing the levels of interferon γ (IFNγ) + or Ki67 + CD8 T cells and decreasing the levels of CD8 + Tregs cells in the tumor and spleen of the hepatoma mice model, indicating that the improvement of TME was manifested by increasing the cytotoxic factor IFNγ expression, enhancing CD8 + T cells proliferation, and weakening CD8 + T cells depletion.@*CONCLUSIONS@#This work suggests that AZD1775 and anti-PD-1 Ab synergistically sensitize hepatoma to radiotherapy by enhancing IR-induced DNA damage and improving cytotoxic CD8 + T cells in TME.

Radiation-induced GATA3 expression in lung epithelial cells and mechanism of RNA methylation / 中国辐射卫生

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.

Research progress in biological effects of low-dose radiation / 中国辐射卫生

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.

Research progress of RNA m 6A modification in malignant tumor and its mechanism of radiotherapy / 中华放射医学与防护杂志

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.

Regulation of neuropilin-1 in radiation-induced transformation of lung epithelial cells / 中华放射医学与防护杂志

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.