Identification of Differentially Expressed Genes Contributing to Radioresistance in Lung Cancer Cells using Microarray Analysis

Abstract

Radiotherapy has played a key role in the control of tumor growth in many cancer patients. It is usually difficult to determine what fraction of the tumor cell population is radioresistant after a course of radiotherapy. The response of tumor cells to radiation is believed to be accompanied by complex changes in the gene expression pattern. It may be possible to use these to sensitize radioresistant tumor cells and improve radiocurability. Based on the biological effects of ionizing radiation, in the present study, we developed one oligonucleotide microarray to analyze the expression of 143 genes in cells of two lung cancer cell lines with different radiosensitivities. Compared to NCI-H446 cells, expression of 18 genes significantly increased the basal levels in the radioresistant A549 cells, in which eight genes were up-regulated and 10 genes were down-regulated. In A549 cells irradiated with 5 Gy, 22 (19 up-regulated and three down-regulated) and 26 (eight up-regulated and 18 down-regulated) differentially expressed genes were found 6 and 24 h after irradiation, respectively. In NCI-H446 cells, the expression of 17 (nine up-regulated and eight down-regulated) and 18 (six up-regulated and 12 down-regulated) genes was altered 6 and 24 h after irradiation, respectively. RT-PCR was performed, and we found that MDM2, BCL2, PKCZ and PIM2 expression levels were increased in A549 cells and decreased in NCI-H446 cells after irradiation. Genes involved in DNA repair, such as XRCC5, ERCC5, ERCC1, RAD9A, ERCC4 and the gene encoding DNA-PK, were found to be increased to a higher level in A549 cells than in NCI-H446 cells. Antisense suppression of MDM2 resulted in increased radiosensitivity of A549 cells. Taken together, these results demonstrate the possibility that a group of genes involved in DNA repair, regulation of the cell cycle, cell proliferation and apoptosis is responsible for the different radioresistance of these two lung cancer cells. This list of genes may be useful in attempts to sensitize the radioresistant lung cancer cells.

Phosphorylation of Ribosomal Protein S3 and Antiapoptotic TRAF2 Protein Mediates Radioresistance in Non-small Cell Lung Cancer Cells

“…Furthermore, to examine whether or not our results are cell line-specific, we used other models for radioresistant and radiosensitive NSCLC cells, NCI-H1299 and NCI-H157, respectively. We reconfirmed that A549 and NCI-H1299 cells are more radioresistant than NCI-H460 and H157 cells in accordance with previous studies (7,(23)(24)(25)(supplemental Fig. S1A).…”

“…and NCI-H460 cells can be used as models for radioresistant and radiosensitive NSCLC cells, respectively, due to their considerable difference in radiosensitivity (7,(23)(24)(25). Based on diverse extraribosomal functions of ribosomal proteins, we hypothesized that they could be associated with tumor radioresistance.…”

Enhancement of radiosensitivity by topoisomerase II inhibitor, amrubicin and amrubicinol, in human lung adenocarcinoma A549 cells and kinetics of apoptosis and necrosis induction

“…Previous reports have clarified that human lung adenocarcinoma A549 cells are radio-or thermo-resistant (9)(10)(11)(12)(13) and have a mutated K-ras gene (14,15) and wild-type p53 gene (15,16). When DNA is damaged, wild-type p53 protein is activated by a phosphorylation signaling pathway, after which it exhibits antitumor effects by inducing either apoptosis or G 1 arrest (17)(18)(19)(20)(21)(22).…”

New therapeutic perspectives in CCDC6 deficient lung cancer cells

“…Recent advances in genomics have identified a number of genetic alterations in NSCLC that could be therapeutically exploited as predictive biomarkers to guide treatment decisions and customize therapy. 2,3 The use of tyrosine kinase inhibitors to target Epidermal Growth Factor Receptor (EGFR), 4 Anaplstic lymphoma kinase (ALK) 5 and RET protooncogene, rearranged during transfection (RET) 6 is effective, but only in small minority of cases (10)(11)(12)(13)(14)(15)(5)(6)(7) and 2% of NSCLC patients, respectively). A vast majority of NSCLCs do not carry the molecular alterations; thus, disease management is an ongoing challenge.…”

“…Elevated DNA repair proficiency has been correlated with radiotherapy resistance and poor survival in NSCLC patients. [7][8][9][10] Inhibition of DNA repair in tumor cells represents an established therapeutic strategy to enhance the effects of chemotherapy or radiation. The poly(ADP-ribose) polymerase (PARP) inhibitors are especially promising in this regard, either as a single agent or combinatorially with other DNA-damaging agents.…”