The expression of miR-424*in vivo and in vitro irradiated A549 cells, tissue and serum samples of non-small cell lung cancer

Abstract

Objective To investigate the expression of miR-424* in 2 and 4 Gy X-ray irradiated A549 cells in vitro and in vivo, as well as in clinical lung tissues and serum sample of non-small cell lung cancer(NSCLC) patients, and to explore its potential role in the diagnosis and prognosis of lung cancer. Methods A549 cells were irradiated with 2 and 4 Gy X-rays, and some of irradiated cells were injected into nude mice through tail vein. Real time quantitative PCR (RT-qPCR) assay was employed to detect the expression of miR-424* in 2 and 4 Gy X-ray irradiated A549 cells in vitro and in vivo, as well as in clinical lung tissues and serum sample of lung cancer patients. Results Compared with the control group, the expression of miR-424* was up-regulated significantly in X-ray irradiated A549 cells at 1, 2, 12, 24 and 48 h post irradiation, respectively (2 Gy: t=-45.886--6.709, P<0.05; 4 Gy: t=-29.087--7.833, P<0.05). Furthermore, the expression of miR-424* was up-regulated in the lung and serum of nude mice with injection of 0, 2 and 4 Gy X-ray irradiated A549 cells, compared with control group (fold change was 9.72, 8.58 and 4.7 with 2 Gy irradiation and 11.93, 9.22 and 8.99 with 4 Gy irradiation, t=-13.243, -12.409, -9.833 in lung and t=-6.436, -3.052, -3.609 in serum, respectively, P<0.05). Out of 11 tissue samples of NSCLC patients, 6 were detected with up-regulated miR-424* expression, and no significant discrepancy of miR-424* expression was detected in two type of NSCLC tissue samples. On the contrary, 43 serum samples were detected with up-regulated miR-424* expression out of 84 serum samples (51.20%) of NSCLC patients (fold change range 1.97 to 17.71), and significant discrepancy of miR-424* expression was shown in two subtypes of NSCLC serum samples [adenocarcinoma: 39.10% (18/46) and squamous carcinoma: 65.8% (25/38)], as well as in serum samples of NSCLC patients with radiotherapy [41.5% (22/53)] and without radiotherapy [67.7% (21/31)] (t=5.919, 5.387, P<0.05, respectively). Conclusions 2 and 4 Gy X-ray irradiation could up-regulate the expression of miR-424* in A549 cells, which might be correlated with the enhanced metastasis of A549 cells induced by X-ray in vivo and in vitro. Furthermore, the expression of miR-424* was up-regulated in over 50% of the tissue and serum samples of NSCLC patients, which might be correlated with the diagnosis of NSCLC subtype and prognosis of radiotherapy. Key words: Non-small cell lung cancer (NSCLC); miR-424*; Irradiation; microRNA