To Study The Expression And Significance Of MiR-143-3P And It’s Target Gene In Colorectal Cancer

Objective：MiRNA microarray was used to screen differently expressed miRNA inCRC tissues, To further investigate study the expression and significance of miR-143-3pand it’s target genes in colorectal cancer and provide clues for further research on themechanism of miRNAs in colorectal cancer.Methods：(1) Microarray analysis was performed to obtain the miRNAs differentlyexpressed in CRC tissues.(2) Bioinformatics technology and internet resources were usedto forecast the targets of miR-143-3p. K-ras and Bcl-2with high predictive values wereselected as candidate targets，and confirmed by the dual-luciferase reporter system.(3)Detecting the expression of K-ras and Bcl-2in the200CRC tissues and50nomal tissueswith tissue microarray and immunohistochemistry (IHC).Results：(1) Result of microarray showed that there are268miRNAs with abnormalexpression in the CRC，including8low expression miRNAs and8high expressionmiRNAs，especially, the expression of miR-143-3p in CRC tissue was significantly lower34.8folds than in normal tissues.(2) Bioinformations technology showed that K-ras and Bcl-2had the high predictive values, therefore, we choose the K-ras and Bcl-2as candidate targetgenes of miR-143-3p to be further explored. Luciferase reporter system showed that theluciferase activity were decreased significantly respectively in miR-143-3p groupcompared to blank group or NC group (K-ras：P<0.01；Bcl-2： P<0.001) after transfectionof wild-type K-ras3′UTR and Bcl-23′UTR plasmid. The above results indicate thatmiR-143-3p inhibits the activity of luciferase through the binding sites of K-ras3’UTR andBcl-23’UTR region，K-ras and Bcl-2are target genes of miR-143-3p.(3) The positiveexpression ratios of K-ras normal colorectal tissue and in colorectal cancer were0.00%and34.00%respectively have significant difference（P<0.01）. The K-ras expression level hasno significant difference with the metastasis of lymph nodes and clinical stage while no significant difference was observed in age, gender， the grade of pathologicaldifferentiation，the depth of invasion and the size of tumo（rP>0.05）. The posive expressionratios of Bcl-2in normal colorectal tissue and in colorectal cancer were24.00%and40.00%respectively with significant difference（P<0.05）. The Bcl-2expression level positivelycorrelated with he grade of pathological differentiation（P<0.05）. however, no significantdifference was observed in age， gender， the depth of invasion and the size of tumor（P>0.05）.Conclusions1. The expression profile of miRNAs are different between CRC tissues and normalcolorectal tissues. Low expression miR-143-3p may play roles in CRC.2. MiR-143-3p could regulate the expression of K-ras and Bcl-2gene mainly attranslation level.3. High expression K-ras and Bcl-2play an important role in occurrence,differentiation status and development in CRC.