The Function And Molecular Mechanism Of MiR-500a And MiR-199a/b-5p In HCC Progression

Liver cancer is one of common malignant tumors across the world.With the constant enhancement of medical level,the prognosis level of liver cancer is enhanced,but the morbidity and death rate are still not optimistic.The occurrence of tumor is a process of polygenes and multistage mutation.The molecule mechanism is very complicated and it is not clear even today.It has very important scientific research significance and clinic value to explore the molecular mechanism of the occurrence and development of tumor on studying valid molecular target in the tumor diagnosis and treatment.With the maturity and wide application of 2G high-throughput sequencing technology,the research of oncology welcomes the age of “data explosion”.A series of database integrating big data of cancer generate correspondingly and mining the big data in tumor database deeply becomes the breakthrough of disclosing the secret veil of tumor development mechanism.TCGA database is the largest tumor database in the world at present.It has many tumor samples and the data type is complete.Thus,it becomes a edge tool of oncological research in recent years.The completion of human genome project(HGP)and the increasingly deep large-scale transcriptome research cause impact to typical regulation mode of gene expression.People find that there is only about 2% of sequence in human genome that can be transcirpted and translated into functional protein,while over 90% sequence is transcripted,but doesn't encode protein.The RNA transcripted by such gene is called nc RNA.With the in-depth research on nc RNA,people find that miRNA plays an important role in regulating gene expression and even in the various important process of biology.It takes an important role in the occurrence and development of tumor.miRNA is a nc RNA with the length about 22 nt.People find that miRNA plays an important role in regulating related gene expression of tumor.It can inhibit the target gene translation process through targeting the target gene m RNA 3'UTR area.Thus,it is deemed as the potential molecular target of tumor diagnosis and treatment.In recent years,people find and disclose many functions and mechanism of miRNA in the occurrence and development of tumor,but the current research is also insufficient,which is mainly embodied at: 1)miRNA has multi-target feature and the target needs to be explored and improved further so as to disclose the complete picture of the occurrence of complicated miRNA-m RNA regulating network in the tumor;2)there is no report for some functions and mechanism of miRNA,which needs a further study.Based on the above research background,there are two parts to study differential expression of liver cancer miRNA in depth in this paper.Part ? Research on function and mechanism of miR-199a/b-5p in the occurrence and development of liver cancerIn the research of this part,through analyzing liver cancer sample miRNA chip data and clinic prognostic data in TCGA databse,we find miR-199a/b-5p reduces in liver cancer and the high expression patient has longer lifetime,which discloses that it may take an important role in the liver cancer.Through detecting miR-199a/b-5p expression in liver cancer texture and cell line,the paper verifies the obvious reduction of miR-199a/b-5p in liver cancer.Next,we focus on exploring the molecular function and mechanism of miR-199a/b-5p that obvious reduction occurs.Through a series of experiments in vitro and vivo,we find miR-199a/b-5p can inhibit the transfer of liver cancer obviously.The main mechanism is to inhibit the excitation of signal channel ROCK1/MLC and PI3K/Akt through the expression of negatively regulating ROCK1,and finally inhibit the transfer of liver cancer.In addition,we find ROCK1 protein level rather than m RNA level behaves obvious up-regulation in liver cancer,which discloses that the up-regulation expression of ROCK1 is mediated by the post-transcriptional control factor and miR-199a/b-5p may be the main post-transcriptional control factor.Through the research in this part,we disclose the new molecule mechanism of miR-199a/b-5p in liver cancer and determines the function and mechanism of ROCK1 in liver cancer further.Part ? Research of function and mechanism of miR-500 a in the occurrence and development of liver cancerIn the first part,through miRNA expression chip data and clinic data in TCGA database,we find miR-500 a appears obvious up-regulation and low expression patients have longer lifetime.Whereas there is no related report about miR-500 a in liver cancer,we studied function and molecular mechanism.Through a series of experiments in vitro and vivo,we find that after inhibiting miR-500 a,the proliferation of liver cancer is inhibited obviously and cell apoptosis is induced.Next,we explores molecular mechanism and find that miR-500 a can target at BID m RNA 3'UTR area,regulate the expression of BID gene negatively and reduce the level of Cleaved-Caspase-3,-9 so as to inhibit the function of liver cancer apoptosis.Through the research in this part,we disclose the molecular function and mechanism of miR-500 a in liver cancer: Through targeting at BID protein,miR-500 a weakens related apoptosis-inducing signal channel so as to inhibit the apoptosis of liver cancer cell.Therefore,miR-500 a is a typical cancer-induced miRNA in liver cancer.