LncRNA MALAT1 Reduces Sensitivity Of Non-small Cell Lung Cancer To Gefitinib

Objective:Investigate the expression of lnc RNA(Long noncoding RNA,lnc RNA)MALAT1(metastasis-associated lung adenocarcinoma transcript 1)in the serum of NSCLC and the correlation between serum expression of MALAT1 with clinical pathological features of NSCLC.Observe gefitinib drug sensitivity before and after the transfection of MALAT1-siRNA in EGFR(Epidermal Growth Factor Receptor)wild-type cell line A549 and discuss the relationship between MALAT1 and EGFR-TKI(Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor)drug resistance.Methods:Detected MALAT1 expression in the serum of 90 cases of NSCLC with real time fluorescence quantitative PCR,and then compared with 30 cases of lung benign tumor and another 30 cases of healthy persons.Respectively detected the MALAT1 expression in the cell lines A549,H1299,95 D,HCC827.The IC50 values of gefitinib before and after transfecting MALAT1-siRNA were analysed by CCK.Flow cytometry technology was used to evaluate the apoptosis rates.Results:1.Compared with the healthy control group,the MALAT1 expression levels in the serum of NSCLC have a statistically significant(P<0.01);The MALAT1 expression levels in the serum of lung benign tumor group have no statistically significant(P>0.05).The expression levels of MALAT1 were not correlated with age,sex,smoking,pathological type,diameter and distant metastasis.MALAT1 were correlated with differentiation(P<0.01),lymph node metastasis(P<0.05),TNM stage(P<0.05).2.Compared with HCC827(EGFR mutant type),the expression levels of MALAT1 in A549(EGFR wild type),H1299(EGFR wild type),95D(EGFR wild type)cell lines were up-regulated significantly.3.The IC50 values of A549(EGFR wild type),H1299(EGFR wild type),95D(EGFR wild type)(39.43±4.43?M?26.93±0.67?M?25.27±1.94?M)were distinctly higher than HCC827(EGFR mutant type)(0.006±0.01?M).4.CCK test results showed that the cell growth inhibition rates of MALAT1-siRNA group cells at different concentrations of gefitinib were higher than those of NC group cells.The IC50 value of MALAT1-siRNA group cells(9.6±2.95)was lower than that of NC group cells(29.91±2.94).The resistance of A549 cells to gefitinib declined by 2.12 times after transfection.5.Flow cytometry technology results showed that after transfecting 48 hours,the average apoptosis rates between NC group cells and MALAT1-siRNA group cells were 9.20±1.85 % and 10.24±3.43%,the average apoptosis rates between NC group cells with gefitinib and MALAT1-siRNA group cells with gefitinib were 14.57±0.41 % and 21.48±2.47%.The apoptosis rate increased significantly in MALAT1-siRNA group cells with gefitinib than NC group cells with gefitinib by statistical analysis(P<0.05).Conclusions:1.Compared with healthy control group and lung benign tumor group,the MALAT1 expression levels in the serum of NSCLC increased significantly.It showed an abnormal expression of MALAT1 in NSCLC.The expression levels of MALAT1 were not correlated with age,sex,smoking,pathological type,diameter and distant metastasis.MALAT1 were correlated with differentiation,lymph node metastasis and TNM stage(P<0.05).It indicated that the MALAT1 in the serum could reflect the degree of disease progression.2.The expression levels of MALAT1 in A549(EGFR wild type),H1299(EGFR wild type),95D(EGFR wild type)cell lines were higher than those of HCC827(EGFR mutant type),which indicated that the expression levels of MALAT1 in EGFR wild type cell lines were overexpressed compared with EGFR mutant type cell lines.3.The IC50 values of A549(EGFR wild type),H1299(EGFR wild type),95D(EGFR wild type)were distinctly higher than HCC827(EGFR mutant type)which revealed that EGFR wild type cell lines were resistant to gefitinib while EGFR mutant type were sensitive to gefitinib.4.Transfection of MALAT1-siRNA to A549 cell line resulted in inhibition of MALAT1 expression and enhancement in sensitivity to gefitinib in A549 cell line,it prompted the partly reversal of gefitinib resistance by MALAT1.