Abstract:
Background Aurora-A plays a key role in regulating centrosome kinase that maintains chromosomal stability, and its abnormal expression is observed in many tumors and associated with poor prognosis and resistant to radiation. However, it remains unclear whether radiation combined with epidermal growth factor tyrosine kinase inhibitor (EGFR-TKI) works in non-small cell lung cancer (NSCLC) cell lines with high Aurora-A expression.
Objective To investigate the effectiveness of radiation in combination with EGFR-TKI in NSCLC cell lines with relatively high expression of Aurora-A.
Methods NSCLC cell lines with relatively high expression of Aurora-A were screened in A549 and GLC82 cell lines, and targeted drugs with more obvious effect on EGFR were selected from Gefitinib and Icotinib. The relationship between the expression of Aurora-A and EGFR downstream signal pathway related proteins (Akt and Stat1), cell cycle distribution and irradiation dose after irradiation plus targeted drugs was compared. The effect of irradiation combined with targeted drugs on cell apoptosis before and after Aurora-A siRNA intervention was detected by flow cytometry, and its effect on the rate of apoptosis was observed by cell clone formation assay.
Results GLC82 cell line was a NSCLC cell line with relatively high expression of Aurora-A, and Icotinib had a more obvious inhibitory effect on the levels of EGFR and its phosphorylated protein in GlC82 cell line with high expression of Aurora-A. No significant alterations in expression of p-EGFR/EGFR, p-Aurora-A/Aurora-A, p-Akt/Akt and p-Stat1/Stat1 were observed in GLC82 cells with combination of Icotinib and radiation of 2 Gy compared to Icotinib alone. Icotinib combined with radiation of 10 Gy resulted in a significant decrease in expression of p-Aurora-A/Aurora-A and p-Akt/Akt (P<0.05). Flow cytometry showed a linear change in GLC82 cell cycle distribution after Icotinib combined with radiation, and the tumor cells were significantly blocked in the G2/M phase. The conventional radiation of 2 Gy did not significantly increase the apoptosis of GLC82 cells (P>0.05), however, the GLC82 cell apoptosis were significantly promoted by increasing the sensitivity of Icotinib, radiation (2, 10 Gy) and Icotinib combined with radiation of 10 Gy after Aurora-A siRNA intervention (P < 0.05). The cell clone formation assay showed that radiation combined with Icotinib significantly promoted GLC82 cell apoptosis compared with radiation alone.
Conclusion Radiation combined with Icotinib can reverse the Aurora-A-induced resistance to radiation and promote apoptosis of GLC82 cells.