Expression And Function Of Hsa＿circ＿0000911 In Lung Adenocarcinoma

Background and objective:Cancer is the leading cause of death worldwide,and lung cancer accounts for about 18.4% among all cancer deaths,which is a huge barrier to shorten human lifespan.Lung adenocarcinoma（LAC）is the most common histology of lung cancer,but its mechanism of pathogenesis and metastasis is still not clear and 5-year survival rate of patients remains low.Circular RNA（circ RNA）is a newly discovered class of RNAs,which are characterized by a closed ring structure and widely expressed in eukaryotic cells.Growing evidence has confirmed that the expression of circ RNAs are dysregulated in LAC,and are involved in the regulation of malignant biological behaviors of LAC cells,thus circ RNAs have the potential to serve as biomarkers for early diagnosis and progression of LAC,as well as therapeutic targets for LAC.Therefore,with the support of gene chip technology,our research group identified differentially expressed circ RNAs in three early LAC tissues and their paired adjacent tissues in our preparatory work.Our previous results showed that hsa_circ₀000911 was down-regulated significantly in LAC tissues.Based on the previous research,this study aims to detect the expression levels of hsa_circ₀000911 in tissue and plasma samples from LAC patients,analyze its diagnostic value,and further explore its biological functions in LAC cells.Methods:（1）Detected and analyzed the expression levels of hsa_circ₀000911 in LAC tissue samples and the correlation with the clinicopathological parameters: quantitative real-time polymerase chain reaction（q RT-PCR）was performed to detect the expression levels of hsa_circ₀000911 in 46 LAC tissue and their paired adjacent tissue samples,and analyzed the association between the expression levels of hsa_circ₀000911 and the clinicopathological parameters of the included patients.（2）Detected and analyzed the expression levels of hsa_circ₀000911 in the plasma samples from LAC patients and its diagnostic value: q RT-PCR was performed to detect the expression levels of hsa_circ₀000911 in the plasma samples from 41 LAC patients and 41 healthy controls;a receiver operating characteristic（ROC）curve was performed to evaluate the diagnostic value of hsa_circ₀000911 in LAC plasma.（3）Explored the biological functions of hsa_circ₀000911 in LAC cells: constructed the over-expression plasmid and transfected it in LAC cells to up-regulate the expression levels of hsa_circ₀000911,and carrying out cell function experiments at 24 hours after transfection;carried out CCK-8 and colony formation assays to assess if hsa_circ₀000911 participates in the regulation of LAC cells proliferation,and carried out scratch and Transwell assays to assess if hsa_circ₀000911 participates in the regulation of LAC cells migration and invasion respectively.Results:（1）Compared to adjacent tissues,hsa_circ₀000911 was significantly low expressed in LAC tissue samples（P=0.0003）,the expression levels of hsa_circ₀000911 was significantly associated with the lymphatic metastasis（P=0.01）and TNM stage（P=0.04）in LAC tissues.（2）Compared to healthy controls,hsa_circ₀000911 was significantly low expressed in the plasma samples from LAC patients（P=0.0001）;the area under ROC curve of hsa_circ₀000911 was 0.811（P<0.001）,and the sensitivity,specificity were 0.951 and 0.635 respectively;subgroup analysis showed that the diagnostic specificity of hsa_circ₀000911 in early LAC was not high.（3）The over-expression plasmid of hsa_circ₀000911 could increase the expression levels of hsa_circ₀000911 in LAC cells effectively;over-expression of hsa_circ₀000911 significantly inhibited the ability of cell proliferation（P<0.01）,migration（P<0.01）,and invasion（P<0.01）.Conclusion:Hsa_circ₀000911 was down-regulated in tissues and plasma from LAC patients,its levels were associated with lymphatic metastasis and TNM stage,and it also had diagnostic value for LAC.However,the diagnostic specificity of hsa_circ₀000911 in early LAC was not high,which is not yet supported hsa_circ₀000911 could act as a early diagnosis biomarker for LAC.In addition,as a tumor suppressor gene,hsa_circ₀000911 inhibited proliferation,migration,and invasion of LAC cells,which suggests that hsa_circ₀000911 has potential value for precise treatment of LAC.