Downregulation of AATK mediates microRNA-558-induced resistance of A549 cells to radiotherapy.

The deregulation of microRNAs (miRNAs) is often implicated in the control of sensitivity to radiotherapy. The objective of the present study was to identify the association between miR­558 and apoptosis­associated tyrosine kinase (AATK), and their importance in regulating the development of resistance to radiotherapy. The current study demonstrated that AATK, a radiosensitization-associated gene, is a target of miR­558 in lung cancer cells, using in silico analysis and a luciferase reporter system. Furthermore, it was determined that transfection of 30 or 50 nM miR­558 mimics and AATK specific siRNA markedly suppressed the mRNA and protein expression of AATK. To determine whether miR­558 was required for lung cancer cell radioresistance, A549 cells were treated with different doses of ionizing radiation, from 0 to 10 Gy, following transfection with miR­558 mimics or AATK specific siRNA. It was determined that the administration of miR­558 mimics or AATK specific siRNA alone did not significantly alter the survival rate of the cells. By contrast, in the cells exposed to 4, 6 or 8 Gy, the administration of miR­558 mimics or AATK specific siRNA significantly promoted cell survival rate and overexpression of AATK reversed this effect. In conclusion, these data demonstrate that the miR­558/AATK cascade is important for the radiosensitization of lung cancer cells and may be a potential radiotherapy target.

Serum miR-152, miR-148a, miR-148b, and miR-21 as novel biomarkers in non-small cell lung cancer screening.

Lung cancer, predominantly by non-small cell lung cancer (NSCLC), is the leading cause of cancer-related deaths over the world. Late diagnosis is one of important reasons for high mortality rate in lung cancer. Current diagnostic approaches have disadvantages such as low accuracy, high cost, invasive procedure, etc. MicroRNAs were previously proposed as promising novel biomarkers in cancer screening. In this study, we evaluated the predictive power of four candidate miRNAs in NSCLC detection. Our study involved 152 NSCLC patients and 300 healthy controls. Blood samples were obtained from the total 452 subjects. After miRNA extraction from serum, the expression of miRNAs in cases and controls were quantified by qRT-PCR and normalized to the level of U6 small RNA. Statistical analyses were performed to compare miRNA levels between cases and controls. Stratified analyses were employed to compare miRNA levels in NSCLC patients with different clinical characteristics. Serum miR-148a, miR-148b, and miR-152 were significantly downregulated in NSCLC patients. However, overexpression of serum miR-21 was observed in NSCLC patients. The combination of four candidate miRNAs exhibited the highest predictive accuracy in NSCLC screening compared with individual miRNAs (AUC = 0.97). Low level of miRNA-148/152 members may associate with advanced stage, large tumor size, malignant cell differentiation, and metastasis. High expression of miR-21 was possibly correlated with large size tumor and advanced cancer stage. Our results showed the dysregulation of miR-148/152 family and miR-21 in NSCLC patients. Hence, the four candidate miRNAs have great potential to serve as promising novel biomarkers in NSCLC screening. Further large-scale studies are needed to validate our results.