Abstract: Objective To investigate the expression and clinical value of long non-coding RNA GAS5 (lncRNA GAS5) and matrix metalloproteinase 9 (MMP9) in the serum of patients with non-small cell lung cancer (NSCLC).Methods A total of 115 NSCLC patients who were treated in our hospital from December 2018 to December 2019 were collected as the NSCLC group.Based on prognosis,they were grouped into a survival group of 94 cases and a death group of 21 cases;another 115 volunteers who were physically healthy in our hospital during the same period were selected as the control group.Real-time fluorescence quantitative PCR (qRT-PCR) was applied to measure serum lncRNA GAS5 level;Enzyme linked immunosorbent assay (ELISA) was applied to measure serum MMP9 level;Pearson was applied to analyze the correlation between serum lncRNA GAS5 level and MMP9 level in NSCLC patients;receiver operating characteristic curve (ROC) was applied to evaluate the value of serum lncRNA GAS5 and MMP9 levels in the diagnosis of NSCLC;multivariate Cox regression was applied to analyze the influencing factors of prognosis in NSCLC patients.Results Compared with the control group,the serum lncRNA GAS5 level in the NSCLC group obviously decreased,while the MMP9 level obviously increased (P<0.05);a negative correlation between serum lncRNA GAS5 level and MMP9 level in NSCLC patients (r=-0.523,P<0.05);the levels of serum lncRNA GAS5 and MMP9 were correlated with tumor diameter,TNM staging,and lymph node metastasis (P<0.05);the area under the curve (AUC) of serum lncRNA GAS5 and MMP9 levels for diagnosing NSCLC was 0.842 and 0.916,respectively,the AUC of the combined diagnosis of the two was 0.952,which was superior to their individual diagnoses (Z=3.904 and 1.982,P<0.05);the serum lncRNA GAS5 level in the death group was obviously lower than that in the survival group,while the serum MMP9 level in the death group was obviously higher than that in the survival group (P<0.05);Multivariate Cox regression analysis showed that high levels of lncRNAGAS5 were independent protective factors for poor prognosis in NSCLC while high levels of MMP9 and lymph node metastasis Migration is an independent risk factor for poor prognosis in NSCLC (P<0.05).Conclusion The serum lncRNA GAS5 level is significantly reduced and MMP9 level is significantly increased in NSCLC patients,both of which have certain potential value in the clinical diagnosis of NSCLC and are factors affecting the poor prognosis of NSCLC.

Key words: long non-coding RNA GAS5, matrix metalloproteinase 9, non small cell lung cancer, clinical value