| Lung cancer is the cancer with the highest incidence and mortality in the world,and the incidence of lung cancer also ranks first in China.Non small cell lung cancer(NSCLC)is a general term for cancer except for large cell lung cancer,that accounts for 80% of lung cancers.Therefore,it is urgent to find an effective method to treat lung cancer.As we all know,radiotherapy is one of the effective treatments for NSCLC,but the 5-year survival rate of patients is merely 10-30%,and the radioresistance has been considered as one of the most important reasons for treatment failure.How to improve the radiosensitivity of NSCLC cells is one of the research focuses.Currently,radiotherapy is usually combined with other tumor treatment methods to treat cancer.By the continuous development of bioinformatics and other technological,the studies of circular RNA(circ RNA)have been increasing in recent years.A large number of studies has shown that compared with normal tissues,circ RNAs are abnormally expressed in tumors,which is related to the occurrence and development of tumors,as well as the resistances of drug and radiation.In this study,transcriptome sequencing was used to detect the differentially expressed circ RNAs among the radioresistant NSCLC cell line A549-R11 and its parental cell line A549.The expression analysis of these transcripts revealed that 164up-regulated circ RNAs and 393 down-regulated circ RNAs in the resistant cell line A549-R11 cells compared with A549 cells.Among them,circ ZNF208 was the most upregulated in A549-R11 cells.Then,the expressions of circ ZNF208 in other resistant cells were analyzed and we found that it was up-regulated in other X-ray resistant cells.Therefore,the high expression of circ ZNF208 may be related to the radioresistance of NSCLC.Next,the inhibition of the proliferation and the radiosensitization were confirmed in A549-R11 and A549 cells after knocking down circ ZNF208 by CCK-8,Ed Uand clone survival analyses.We also found that circ ZNF208 was enriched in the cytoplasm instead of the nuclear.So,it was hypothesized that circ ZNF208 regulated the radiosensitivity of NSCLC through competing endogenous RNA(ce RNA).The mi RNAs interaction with circ ZNF208 were predicted through the three databases of mi Randa,RNA hybrid and Target Scan.Mi R-7-5p was screened as the candidate through the negative correlation with circ ZNF208 expression in the sequencing data.The expression of mi R-7-5p was negatively correlated with circ ZNF208 by q PCR.The interaction between circ ZNF208 and mi R-7-5p was demonstrated through AGO2 and biotin-labeled RNA pulldown experiments.The results from phenotypic experiments showed that mi R-7-5p could regulate the proliferation and X-ray radiosensitivity in A549 and A549-R11 cells.Furthermore,it was predicted that SNCA was the target gene of mi R-7-5p through bioinformatics,and the interaction between mi R-7-5p and SNCA was proved by dual-luciferase experiment.It was discovered that overexpression of SNCA can promote the proliferation of A549 and A549-R11 cells and increase the resistance to X-ray radiation by CCK-8,Ed U and clone survival analyses.Through gene enrichment analysis(GSEA),we found that SNCA expression may be related to JAK/STAT signaling pathway and it was confirmed by Western blot experiments after overexpression of SNCA.The results from rescues experiments showed that circ ZNF208/mi R-7-5p/SNCA signal axis regulated the sensitivity of NSCLC to X-rays irradiation.In addition,the radiosensitization effect of circ ZNF208 was not observed in NSCLC cells exposed to high-LET carbon ions through the clone survival experiment.In summary,circ ZNF208 could regulates the sensitivity of NSCLC to X-rays through the mi R-7-5p/SNCA signal axis and JAK/STAT signal pathway.Thereby circ ZNF208 may be a potential target to improve the sensitivity of NSCLC in radiotherapy.In addition,circ ZNF208 might serve as a potential biomarker and therapeutic target for NSCLC treatment with radiotherapy of different modalities. |
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