CircPARP4 Expression In Lung Adenocarcinoma And Its Role In The Development Of Lung Adenocarcinoma

Objective To study the relationship between circPARP4 expression and lung adenocarcinoma,and explore the role of circPARP4 in the development of lung adenocarcinoma.Methods(1)Cultured the bronchial epithelial cells(BEAS-2B)and lung adenocarcinoma cell line(H1299),three strains of BEAS-2B and H1299 cells were selected for second-generation sequencing,and all circRNAs sequences were obtained.All circRNAs sequences were analyzed to obtain the differential circRNA expression profile.(2)The sequencing results of different circRNAs expression profiles were compared to the circBase database,and the significantly down-regulated circRNA in H1299 cells was selected as the target circRNA.The UCSC database was used to further analyze the molecular source and structure of target circRNA.(3)Collected the urgical samples of 20 patients of lung adenocarcinoma,which by real-time quantitative PCR(qrt-pcr)verified the expression of target circRNA in each sample and adjacent tissues.Analyzed the relationship between the expression level of target circRNA and the clinicopathological parameters of patients with lung adenocarcinoma.(4)By The RBPDB website,we can predict the target circRNA binding proteins,and the TCGA database was used to analyze the overall expression of RNA binding proteins(RBP)in lung adenocarcinoma,then we can speculate the influence of circRNA expression on the occurrence and development of lung adenocarcinoma.Furthermore,GO and KEGG pathway analysis were performed on the downstream target genes of circRNA to speculate the possible biological functions and pathways involved in circRNA.Results(1)Compared with BEAS-2B cells,460 circRNAs were differentially expressed in H1299 cells,among which 278 were up-regulated and 182 were down-regulated.The differentially expressed circRNAs were distributed on all chromosomes,and 87% of the differentially expressed circRNAs were derived from exons,followed by overlapped regions.(2)The target circRNA(chr13:25051839-25052414-)was derived from the PARP4 gene and named as circPARP4,which was significantly down-regulated in H1299cells(Fold change value 3,p value =0.033).The PARP4 gene is located on human chromosome 13,and circPARP4 is formed from the 13 th and 14 th exons of the PARP4 gene with an intron transcription in reverse into a ring,it's 341 nt.(3)It was further verified that the expression of circPARP4 in lung adenocarcinoma tissues was consistent with that in H1299 cells,that is,the expression of circPARP4 in lung adenocarcinoma tissues decreased compared with that in paracancer tissues.the expression level of circPARP4 was independent of tumor diameter and lymph node metastasis in age and sex,and was significantly correlated with TNM stage,that is,the higher the TNM stage,the lower the expression level of circPARP4.(4)Combined with bioinformatics analysis,it was found that circPARP4 could bind to 16 types of RBP,among which SNRPA and ELAVL1 proteins were differentially expressed in lung adenocarcinoma tissues.Moreover,patients with lung adenocarcinoma with high expression of SNRPA and ELAVL1 proteins had worse prognosis than those with low expression.Through GO and KEGG analysis,it was found that the downstream target genes of circPARP4 were mainly related to basic biological functions such as viral nucleocapsid protein binding formed by mRNA processing,and were involved in the PI3K-Akt signaling pathway.Conclusion(1)The expression level of circPARP4 in both lung adenocarcinoma cell lines and lung adenocarcinoma tissues was significantly reduced.The expression level ofcircPARP4 was not related to tumor diameter and lymph node metastasis of age and gender,but was negatively correlated with TNM stage.(2)circPARP4 binding to ELAVL1/SNRPA may regulate the downstream PI3k-Akt signaling pathway and inhibit the progression of lung adenocarcinoma.