Figure 1.

Higher IRAK2 expression was associated with a higher radiosensitivity in the context of parental (i.e., OML1) and radioresistant (i.e., OML1-R) OSCC cells. (A) After exposure to 0, 4, and 10 Gy IR, colony-formation assay confirmed that OML1-R cells were relatively radioresistant when compared with parental OML1 cells. (B) Venn diagram showed the number of genes with apparent expression change before and after irradiation in OML1 and OML1-R cells (left). Bar graphs displayed 19 genes were up-regulated in OML1 cells, using a filter criterion at least 1.5-fold change with P < 0.05. By setting a threshold of RPKM>2, we identified eight reliable transcripts that were largely differentially expressed between the OML1 and OML1-R cells. The graph showed relative fold change in gene expression: control versus IR-treated cells (right). (C) The RPKM value of IRAK2 expression was plotted for OML1 and OML1-R cells treated with 4 Gy. (D) qPCR and (E) Western blotting revealed that IRAK2 expression, including mRNA and protein levels, were pronouncedly elevated in parental OML1, but not OML1-R cells. Densitometry-derived values (bottom) were normalized with the control set as 1. β-actin served as the loading control for normalization.