The Research On The Mechanism Of LncRNA MIAT Regulating The Progress Of Lung Adenocarcinoma

Background and Objective: Lung cancer is a serious threat to human health.The latest statistics show that lung cancer is one of the malignant tumors with the highest incidence and mortality in the world,and lung adenocarcinoma(LUAD)is the most dominant tissue type.Although progress has been made in the diagnosis and treatment of lung adenocarcinoma,the overall prognosis for patients with lung adenocarcinoma is poor.Therefore,it is of great significance to further study the pathogenesis and development of lung adenocarcinoma and explore new diagnostic markers and therapeutic targets for the diagnosis and treatment of lung adenocarcinoma.A large number of studies have shown that dysregulated lncRNA(long non-coding RNA)plays an important role in a variety of key biological processes in tumor cells,affecting the occurrence and development of tumors by regulating cell proliferation,migration,invasion,apoptosis and other functions.The abnormal expression of lncRNA in tumor tissues and its regulatory effect on tumor progression reveal its important value as a novel tumor diagnostic marker and therapeutic target.LncRNA MIAT(myocardial infarction associated transcript)was identified as an lncRNA in 2006 and is highly conserved in mammals,although lncRNA MIAT was initially associated with myocardial infarction.However,more and more studies have found that lncRNA MIAT is abnormally expressed in a variety of tumor diseases.A large number of in vivo and in vitro experiments have confirmed that lncRNA MIAT is involved in regulating the occurrence and development of hepatocellular carcinoma,gastric cancer,acute myeloid leukemia,cervical cancer and other malignant tumors.However,its role and mechanism in the occurrence and development of lung adenocarcinoma are rarely reported.EZH2(enhancer of zeste homolog 2,EZH2)is a lysine histone methyltransferase,an enzymatic catalytic subunit of polycomb inhibition complex 2(PRC2).In tumor cells,overexpression of EZH2 can turn off many normally activated tumor suppressor factors by methylating histone lysine residues,and thus play a role in promoting tumor progression.It has been shown in the literature that EZH2 can regulate the progression of malignant tumors such as melanoma and prostate cancer through related mechanisms.In recent years,a large number of studies have shown that lncRNA can bind to EZH2,mediate the regulation of its downstream gene expression,and then affect the progression of malignant tumors.Our bioinformatics analysis results suggest that lncRNA MIAT may interact with EZH2,but no studies have yet shown that lncRNA MIAT can affect the malignant biological behavior of LUAD through interaction with EZH2.Therefore,this study aims to explore the expression of lncRNA MIAT,EZH2 and their downstream target genes in LUAD and their effects on the function of LUAD cells,as well as their molecular mechanism in the development of LUAD,so as to provide a basis for the diagnosis and treatment of LUAD patients.Methods:1.The expression difference of lncRNA MIAT in lung adenocarcinoma tissues and its expression in NSCLC cell lines was detected by RT-PCR.2.The effects of lncRNA MIAT on cell proliferation,migration and invasion were detected by CCK8,colony formation test and Transwell test.3.The expression of EZH2 in lung adenocarcinoma tissues and its difference in NSCLC cell lines were detected by RT-PCR and immunohistochemistry.The possibility of binding LncRNA MIAT to EZH2 was analyzed by biological database,and the ability of MIAT to bind to EZH2 was verified by RIP and RNA Pull down experiments.4.After overexpression of EZH2,the regulatory effects of EZH2 on SPRED1 and SPOCK2 were verified by RT-PCR,Western blot and luciferase experiments.5.The expression changes of SPOCK2 and SPRED1 and the methylation level of H3k273 after lncRNA MIAT knockdown were detected by RT-PCR and Western blot.6.The expression of SPOCK2 and SPRED1 in LUAD and their differences in NSCLC cell lines were analyzed by means of bioinformation database and RT-PCR assay.The ability of SPOCK2 and SPRED1 to regulate the proliferation,migration and invasion of LUAD cells was detected by CCK8 test,colony formation test,scratch test and transwell test.The effect of overexpression of SPOCK2 and SPRED1 on the growth of LUAD cells in vivo was detected by tumor formation experiment in nude mice.Results:1.lncRNA MIAT is significantly highly expressed in lung adenocarcinoma tissues.Knocking down lncRNA MIAT can significantly reduce the proliferation and invasion ability of LUAD cells.2.EZH2 is highly expressed in lung adenocarcinoma tissues and NSCLC cell lines;In the cell,lncRNA MIAT can bind to EZH2.After knocking down lncRNA MIAT,the methylation level of H3k27 was down-regulated,and the expressions of SPOCK2 and SPRED1 were up-regulated.3.SPOCK2 and SPRED1 are low expressed in lung adenocarcinoma tissues and NSCLC cell lines,and overexpression of SPOCK2 and SPRED1 inhibits the proliferation,migration and invasion ability of LUAD cells,while overexpression of SPOCK2 and SPRED1 inhibits the proliferation ability of LUAD cells in vivo.Conclusion:By recruiting EZH2 and then methylating H3K27,lncRNA MIAT inhibited the expression of SPOCK2 and SPRED1,promoting LUAD’s bad oncology behavior,which may be a new target for LUAD treatment.