Abstract: Objective To investigate the impacts of long non coding RNA (LncRNA)PH domain containing 5 antisense RNA 1 (FGD5-AS1) on the proliferation,migration,and invasion of colorectal cancer (CRC) cells by regulating the miR-299-5p/recombinant lysine specific demethylase 4B (KDM4B) axis.Methods The expressions of LncRNA FGD5-AS1,miR-299-5p,and KDM4B were detected by qRT-PCR in the surgically resected CRC tissues and adjacent tissues of 34 CRC patients CRC cells HCT116 were separated into si-NC group,si-FGD5-AS1 group,si-FGD5-AS1+inhibitor NC group,and si-FGD5-AS1+miR-299-5p inhibitor group.The levels of mRNA in each group were detected.CCK8,scratch assay,and Transwell assay were ap[plied to detect the proliferation,migration,and invasion of HCT116 cells in each group.Western blot was applied to detect the expression of proteins.Dual luciferase reporter gene assay verified the interaction mechanism between LncRNA FGD5-AS1 and miR-299-5p,and between miR-299-5p and KDM4B.Results LncRNA FGD5-AS1 and KDM4B were highly expressed in CRC tissue,while miR-299-5p was low expressed in CRC tissue (P<0.05).The expression of LncRNA FGD5-AS1 mRNA,KDM4B mRNA,OD450,scratch healing rate,invasion number,PCNA,MMP-2,MMP-9,KDM4B in the si-FGD5-AS1 group were lower than those in the si-NC group,the expression of miR-299-5p mRNA was higher than that in the si-NC group (P<0.05).Compared with the si-FGD5-AS1 group and si-FGD5-AS1+inhibitor NC group,the expression of miR-299-5p in the si-FGD5-AS1+miR-299-5p inhibitor group decreased (P<0.05),the KDM4B mRNA,OD450,scratch healing rate,number of invasions,and expression of PCNA,MMP-2,MMP-9,KDM4B increased (P<0.05).LncRNA FGD5-AS1 targeted negative regulation of miR-299-5p,while miR-299-5p targeted negative regulation of KDM4B.Conclusion Knocking down LncRNA FGD5-AS1 may inhibit the proliferation,migration,and invasion of CRC cells,and its mechanism may be achieved by regulating the miR-299-5p/KDM4B signaling axis.

Key words: long non coding RNA PH domain containing 5 antisense RNA 1, micro RNA-299-5p, recombinant lysine specific demethylase 4B, colorectal cancer, proliferation, migration, invasion