Low-dose ionizing radiation: Effects on the proliferation and migration of lens epithelial cells via activation of the Wnt/β-catenin pathway

Eye lens opacification (cataract) induced by ionizing radiation is an important concern for radiation protection. Human lens epithelial cells (HLE-B3) were irradiated with γ-rays and radiation effects, including cell proliferation, cell migration, cell cycle distribution, and other changes related to the β-catenin pathway, were determined after 8-72 h and 7 d. In an in vivo model, mice were irradiated; DNA damage (γH2AX foci) in the cell nucleus of the anterior capsule of the lens was detected within 1 h, and radiation effects on the anterior and posterior lens capsules were observed after 3 months. Low-dose ionizing radiation promoted cell proliferation and migration. The expression levels of β-catenin, cyclin D1, and c-Myc were significantly increased in HLE-B3 cells after irradiation and β-catenin was translocated into the cell nucleus (activation of the Wnt/β-catenin pathway). In C57BL/6 J mouse lens, even a very low irradiation dose (0.05 Gy) induced the formation of γH2AX foci, 1 h after irradiation. At 3 months, migratory cells were found in the posterior capsule; expression of β-catenin was increased and it was clustered at the nucleus in the epithelial cells of the lens anterior capsule. The Wnt/β-catenin signaling pathway may an important role in promoting abnormal proliferation and migration of lens epithelial cells after low-dose irradiation.