Identifying the genetic pattern of conventional fractionated and hypofractionated radiotherapy using whole genome expression microarray in a non-small-cell lung cancer cell line / 中国肿瘤临床

ABSTRACT

Objective:To obtain stable radioresistant non-small-cell lung cancer (NSCLC) cell lines and identify the genetic pattern of conventional fractioned and hypofractionated radiotherapy. Methods:A549 NSCLC cells were treated with 6 MV of x-rays through conventional fractionated (2 Gy, 17 f) and hypofractionated irradiation (4 Gy, 7 f) to establish a radiation resistance cell model. Tumor cell radioresistance was determined using a clonogenic assay andγ-H2AX immunofluorescence staining combined with confocal microscopy. After extracting total mRNA from the cells, a whole genome expression microarray was applied to detect differential gene expression. The genes with at least a twofold increase in expression (P<0.05) were analyzed, and the pathway (Q<0.05) methods were used to further analyze the chip results. Results:After irradiating the A549 cells, two radioresistant cell lines were obtained, namely, the A549R2Gy-R and the A549R4Gy-R cell lines. The A549R2Gy-R cell line was radioresistant to the conventional fractionated irradiation, whereas the A549R4Gy-R cell line was ra-dioresistant to hypofractionated irradiation. Microarray analysis showed that the A549R2Gy-R cells exhibited 1 701 differentially expressed genes (357 upregulated, 1 344 downregulated) compared with the parental A549 cell. By contrast, the hypofractionated irradiation-resistant A549R4Gy-R cells had 944 upregulated genes and 2 602 downregulated genes compared with the A549 cells. The A549R2Gy-R cells exhibited 318 upregulated genes and 699 downregulated genes compared with the A549R4Gy-R cells. Several signaling pathways were implicated in radioresistance when conventional fractionated radiotherapy was compared with hypofractionated irradiation radiotherapy using path way-significant enrichment analysis, especially the PI3K and Erb B channel signaling pathway kinase. Conclusion:Multiple genes and signaling pathways are involved in the development of radiation resistance in NSCLC. The underlined radioresistance mechanisms under conventional and hypofractionated radiotherapy need further study and elucidation to provide new targets for drug development.