Study On The Mechanism Of MALAT1 In Reducing The Resistance To Gefitinib In Non Small Cell Lung Cancer Patients With Lin28B

Objective:In the treatment of cancer,the drug resistance of tumor cells is a difficult problem to be solved.Previous studies have found that the down-regulation of MALAT1 expression can reverse the resistance of A549 cells to gefitinib.But the specific mechanism is not clear.Lin28 is a tumor stem cell related gene,which is expressed in a variety of tumors and is associated with poor differentiation and poor prognosis.Lin28(Lin28A)and its homologous gene Lin28B are closely related to the occurrence,progression and prognosis of malignant tumor,and the formation of multiple functional stem cells.Epithelial mesenchymal transition(EMT)refers to the phenomenon of epithelial cells into mesenchymal cells under the stimulation of external environment(EMT).The occurrence of EMT is closely related to tumor formation and metastasis.In recent years,more and more studies have found that the drug resistance of tumor cells is closely related to the occurrence of tumor stem cell gene Lin28 and EMT.In this study,we investigated whether inhibition of MALAT1 expression can reverse the resistance of lung cancer cell line A549 to gefitinib by affecting the expression of Lin28 and EMT.Methods:(1)PCR and Western were used to detect the expression levels of Lin28A and Lin28B in A549(drug resistance)cell lines and HCC827(sensitive)cell lines.(2)The expression levels of E-Cadherin and Vimentin in A549(drug resistance)cell lines and HCC827(sensitive)cell lines were detected by Western Blot method.(3)A549(drug resistant)cells were transfected with siRNA to detect the transfection efficiency and inhibit the expression of MALAT1.(4)CCK was used to detect the resistance of A549 to gefitinib before and after transfection.(5)PCR and Western Blot were used to detect the expression level of Lin28B in the transfected group(Inhibition of MALAT1 expression).(6)Western Blot method was used to detect the expression level of E-Cadherin and Vimentin in A549(resistant)cell lines in the transfected group(Inhibition of MALAT1 expression).Results:(1)In the A549 cell line and HCC827 cell lines,expression of Lin28A was different,but the difference was not statistically significant(P>0.05);Lin28B gene in A549 and protein levels were significantly higher than that of HCC827,with statistical significance(P<0.05);(2)Compared with HCC827 cell line,the expression level of E-Cadherin protein in A549 cell line was down regulated,with statistical significance(P<0.05).The expression level of Vimentin protein was up-regulated,which was statistically significant(P<0.05);(3)Compared with the untransfected group,the drug resistance of the transfection group to gefitinib decreased(P<0.05),which was statistically significant.(4)Compared with untransfected group,the expression of MALAT1 was inhibited in the transfected group and the expression level of Lin28B gene and protein were decreased(P<0.05).(5)Compared with the control group,the expression level of E-Cadherin in the transfected group was significantly higher than that of the control group(P<0.05).The expression level of Vimentin was decreased,and the difference was statistically significant(P<0.05);Conclusions:(1)Lin28B and EMT may be involved in the mechanism of A549 resistance to gefitinib.(2)MALAT1 may reverse the resistance of A549 to gefitinib by affecting Lin28B.(3)MALAT1 may reverse the resistance of A549 to gefitinib by influencing EMT.