To investigate the relationship between autophagy and metastasis of nasopharyngeal cancer (NPC) cell lines 5-8F and 6-10B after X-ray irradiation and the related mechanism.

Two substrains, 5-8F and 6-10B, of the NPC cell line SUNE1, with high and low metastatic potentials, respectively, were used in our study. After 4 Gy X-ray irradiation, 5-8F cells were treated with rapamycin (2.0 μmol/L) to induce autophagy and 6-10B cells were treated with LY294002(10 μmol/L) to inhibit autophagy. The autophagy and metastatic activity of NPC cells were determined using qRT-PCR, Western blot, Transwell assay, laser confocal microscopy, and transmission electron microscopy.

5-8F cells showed a lower level of autophagy than 6-10B cells after X-ray irradiation. Rapamycin increased the autophagy and inhibited the metastasis of 5-8F cells after irradiation, while LY294002 inhibited the autophagy and increased the metastasis of 6-10B cells.

NPC 5-8F cells, which have a high metastatic potential, have a lower level of autophagy than 6-10B cells, which have a low metastatic potential. Autophagic inhibition could increase the metastatic activity of NPC cells, while autophagic activation could reduce their metastatic activity. Mechanistic analysis indicates that the PI3K/AKT/mTOR pathway is involved in this process.

X-ray irradiation; Cell line, nasopharyngeal; Autophagy; Metastasis