Differential Expression Profile Of Circular RNA In Plasma Exosomes Of HCC And Its Correlation With Clinicopathological Features

BackgroudHepatocellular Carcinoma(HCC)is one of the most common malignant tumors in China,with the third highest fatality rate and the second highest cancer-related mortality rate.About 300,000 people die of Hepatocellular Carcinoma every year in China,which seriously threatens the development of national economy and the health of the population in China.The occurrence of HCC is closely related to hepatitis B,which has a high incidence in China.Currently,surgery,radiation and chemotherapy is a major means of treatment of liver cancer,liver transplantation,but because of the disease onset hidden,although AFP(Alpha fetoprotein,AFP)used in the diagnosis of HCC has been widely recognized,but there is more than a piece of literature reported that AFP used to diagnose and detect HCC has certain limitations,namely according to the current diagnostic criteria for HCC,when abnormal results AFP and imaging examination,often has developed to the late,many patients have lost the precious opportunity to early intervention and treatment,so the overall prognosis of HCC patients around the world.Circ RNAs are a special class of long-stranded non-coding Rnas.Their unique circular structure enables them to escape from the degradation of RNase and has strong intracellular stability.Currently,circ RNA is believed to act as a molecular "sponge" acting as micrornas,regulating gene expression,splicing and transcription in parents.It also plays an important role in the occurrence and development of many diseases including tumors and may be a new biomarker.The expression of circ RNA in human tissues is tissue specific,and it has been found that a variety of circ RNA are related to liver cancer(such as HSA＿circ＿0001649,Circ RNA-100338,HAS＿circ＿0004018,HSA＿circ＿0005075,circ ZKSCAN1,etc.)and play an important role in the development of HCC.As a messenger,exosomes play a crucial role in the carcinogenesis process by carrying and transmitting oncogenic molecules(including mi RNA,long non-coding RNA and circ RNA)in cell communication.In recent years,some studies have shown that circ RNA is enriched and stable in exosomes and is expected to be a biomarker for clinical diseases.However,there are few reports on plasma and plasma exosomes in liver cancer patients.The purpose of this study was to find circ RNA differentially expressed in plasma exosomes of HCC and normal people,explore the role of some differentially expressed circ RNA in HCC and explore its possible functional mechanism,and provide new directions and theoretical basis for the clinical diagnosis and treatment of HCC.ObjectivesTranscriptome sequencing and quantitative real-time PCR were used to search for early diagnostic markers and possible therapeutic targets for HCC.MethodsExosomes were extracted by hypervelocity centrifugation,and the presence of exosomes was confirmed by western blot,transmission electron microscopy and nanoparticle tracking analysis.Subsequently,the plasma circ RNA expression profile was screened by transcriptome sequencing(RNA-SEQ),and circ RNA in plasma exosomes was extracted from 41 HCC patients and 20 normal controls,and the sequencing results were verified by fluorescence quantitative real-time polymerase chain reaction(QRT-PCR).ResultsCompared with the normal group,60 circ RNA expressions were up-regulated(fold change ≥4.0)and 24 circ RNA expressions were down-regulated(fold change<2.0)in the HCC group.Among them,upregulation of HSA＿circ＿0126267 was verified by q RT PCR,and the results showed that its expression in HCC group was significantly higher than that of the normal group,with statistically significant difference(P < 0.05).Correlation analysis showed that h SA＿circ＿0126267 expression was not significantly correlated with tumor size,cirrhosis,AFP level,hepatitis B,single or multiple tumors,gender,age and other clinical factors,but was significantly correlated with microvascular invasion(P=0.0079)and Edmondson-Steiner grading(P= 0.0008),i.e.,tumor differentiation degree.ConclusionsThe circ RNA expression profile of plasma exosomes in hepatocellular carcinoma was first reported.It was confirmed that HSA＿circ＿0126267 was highly expressed in plasma exosomes of HCC patients,and its high expression was significantly correlated with microvascular invasion and high degree of tumor differentiation.