Effects of ionizing radiation on the miR-21 expression in A549 cells in vitro and in vivo / 中华放射医学与防护杂志

ABSTRACT

Objective To investigate the expressions of miR-21 in clinical lung tissues,serum of lung cancer patients and X-ray irradiated A549 cells in vitro and in vivo.Methods A549 cells were irradiated with 2 and 4 Gy X-rays,and pulmonary metastasis model of lung cancer in nude mice was established to detect the expression of miR-21 in vitro and in vivo,as well as in clinical lung tissues of different pathological types serum sample of lung cancer patients and NSCLC patients whether or not received radiotherapy.The survival rate was further analyzed in the above mention NSCLC patients.Results The miR-21 expressions was up-regulated in 60.0％ of tissue samples of NSCLC patients,and it was up-regulated in 50.5％ serum samples of lung cancer patients (52 out of 103).The miR-21 expressions in lung adenocarcinoma and squamous cell carcinoma had significant difference (x2 =5.766,P ＜ 0.05).In the serum samples of 87 NSCLC patients,miR-21 was detected in 66.7％ samples from the patients of radiotherapy but only 39.6％ of patients without radiotherapy (x2 =6.321,P ＜ 0.05).Kaplan-Meier curves showed that the survival rate of patients with low miR-21 expression was higher than that with high miR-21 expression (P ＜ 0.05).Multivariate Cox regression analysis demonstrated that the miR-21 expression,regional lymph node metastasis and radiotherapy were independent prognostic factors for NSCLC patients.The expression of miR-21 was up-regulated significantly in X-ray irradiated A549 cells at different time-points after irradiation (t =-7.552--1.206,P ＜ 0.05).Furthermore,the expression of miR-21was up-regulated in the serum and lung of nude mice (t =-47.845--2.356,P ＜ 0.05).Conclusions The X-ray irradiation could up-regulate the expression of miR-21 in A549 cells in vitro and in vivo,which might be correlated with the enhanced metastasis of A549 cells.