Study Of The Radiosensitivity Of Colon Cancer Influenced By Interaction Mechanism Between Long Noncoding RNA-MALAT1 And Hsa-miR-1

Background and Aims: In recent years, the incidence of colon cancer increased year by year.Many studies show that long noncoding RNA is aberrantly expressed in colon cancer(CRC).Preoperative radiotherapy has become the standard treatment process of locally advanced colon cancer patients,however a considerable number of colon cancers are resistant to radiotherapy.Lnc RNA-MALAT1 is a cancer-promoting gene, while hsa-mi R-1 is a tumor suppressor gene.In present study, we try to prove the influence of the two genes on tumor radiosensitivity and the interaction mechanism between the two genes.Methods:1.Through clone forming experiments irradiation resistant strains and irradiation sensitive strainswere slected from the seven strains of colon cancercells.High-throughput sequencing was used to screen the radiation induced differentially expressed Lnc RNA.Then bioinformatics analysis of differentially expressed Lnc RNA was performed.2.Real-time quantitative PCR technology was used to detect the expression of Lnc RNA-MALAT1 and hsa-mi R-1 in colon cancer cells and colon cancer tissues.3.Celltransfection was used to upregulate the expression of the Lnc RNA-MALAT1 or downregulate the expression of the hsa-mi R-1.Then different treatment groups were exposed to irradiation.MTT, clonogenic cell survival assay,wound healing and apoptosis were used to assess the cellviability, proliferation,migration and level of apoptosis respectively.Western blot was used to test the expression of MMP-2 、 MMP-9 、 Ecadherin、Bax and Bcl-2.4.Bioinformatics analysis was used to predict the binding sites between Lnc RNA-MALAT1 and hsa-mi R-1.Luciferase report gene containing this putative binding sites was designed,then the vitality of luciferase report gene was tested to verify the combiningcapacity between Lnc RNA-MALAT1 and hsa-mi R–1.Through regulating the expression of the Lnc RNA-MALAT1 or hsa-mi R-1 respectively,we can further verify the interaction mechanism between Lnc RNA-MALAT1 and hsa-mi R-1.Results:1.Through the clone forming experiment, we found CCL244 colon cancer cell lines were irradiation resistant strains while HCT116 colon cancer cell lines were irradiation sensitive strains. High-throughput sequencing shows that 24 lnc RNAs were differentially expressed in the two strains.2.Bioinformatics analysis of differentially expressed Lnc RNAs show that Lnc RNA-MALAT1 has strong micrornas combining ability and mi R-1 is its target.3.Along with the increase of the irradiation dose,the expression of Lnc RNA-MALAT1 was increased but the expression of has-mi R–1 was decreased,and the expression of Lnc RNA-MALAT1 and hsa-mi R-1 presented the irradiation dose-dependent and time-dependent.4.Compared with the paired colon tissues, the expression of Lnc RNA-MALAT1 was high in colon cancer tissues while the the expression of mi R–1 was downregulated in colon cancer tissues.5.Upregulating the expression of the Lnc RNA-MALAT1 or downregulating the expression of the hsa-mi R-1 along with the radiation processing, we found that the viability,proliferation and migration of cells were significantly suppressed.The expression of MMP 2, MMP9 and Bcl-2 in CCL244 cells were also decreased.The expression of E-cadherin and Bax were increased and the apoptosis rate was also increased in CCL244 cells.6.Luciferase assay shows that the 3 ’end of Lnc RNA-MALAT1 contains a putative hsa-mi R-1 target site and real-time quantitative PCR show that hsa-mi R-1 can regulat the expression of Lnc RNA-MALAT1.Conclusions:Lnc RNA-MALAT1 can regualte the radiosensitivity of coloncancer.Through combining the 3 ’end of Lnc RNA-MALAT1 and inhibiting its expression hsa-mi R-1 can increase the radiosensitivity of colon cancer.