Radiation engenders converse migration and invasion in colorectal cancer cells through opposite modulation of ANXA2/AKT/GSK3ß pathway.

Radiation therapy is an effective non-surgical means to achieve local control for various solid tumors including colorectal cancer (CRC), but metastasis and recurrences after conventional radiotherapy remains a major obstacle in clinical practice, and the knowledge concerning the changes of metastatic potential after heavy ion radiation is still limited. This study investigated how radiation, including γ- and carbon ion radiation, would change the metastatic capacity of two CRC cell lines, HCT116 and DLD-1, and examined the underlying molecular mechanisms. We found that the migration and invasion was enhanced in DLD-1 cells but impaired in HCT116 cells in vitro and in vivo after radiation of γ-rays or carbons, and radiation induced epithelial mesenchymal transition (EMT) in DLD-1 cells but mesenchymal epithelial transition (MET) in HCT116 cells. The expression of snail, a key inducer of EMT, was significantly enhanced by inhibition of glycogen synthase kinase-3ß (GSK3ß) in both cell lines, suggesting the modulation of snail was alike in the two CRC cell lines. However, radiation inactivated GSK3ß through stimulating the phosphorylation of AKT and GSK3ß at Ser473 and Ser9 in DLD-1 cells respectively, but activated GSK3ß by decreasing the expression of pAKTSer473 and pGSK3ßSer9 or increasing the phosphorylation of GSK3ß at Tyr216 in HCT116 cells. Therefore, the above inverted motility changes was due to the opposite modulation of AKT/GSK3ß signaling pathway by radiation, which was further verified in other type of cancer cell lines including MCF-7, U251 and A549 cells. Moreover, it was found that annexin A2 (ANAX2) directly bound with GSK3ß and acted as a negative regulator of GSK3ß upon radiation. Knocking-down ANXA2 gene reversed the enhanced migration of the irradiated DLD-1 cells and strengthened radiation-impaired migration of HCT116 cells. Collectively, this study reveals that the change of cellular motility after radiation is independent of radiation type but is correlated with the inherent of cells.