Radiosensitivity and Radiation-Induced Autophagy in Thyroid Follicular Epithelial Cells of Immature and Adult Rats

暴露于电离辐射（IR），特别是在儿童时期，是甲状腺癌的一个众所周知的危险因素。为了评估不同年龄大鼠甲状腺滤泡上皮细胞的放射敏感性，我们分析了8Gy x射线照射72 h后未成熟（4 W）和成年（8 M）大鼠甲状腺的组织学改变、凋亡诱导、细胞增殖、DNA损伤反应分子表达和自噬诱导。ir诱导的细胞凋亡未被检测到，且p53的Ser15磷酸化表达和53BP1核病灶与年龄无关。4W时，甲状腺滤泡细胞细胞质呈空泡样改变。辐照后4W组ki67阳性细胞明显减少。4W细胞有自噬体，8M细胞无自噬体。LC3-II和p62以及调控自噬的基因在4W时表达增加，而在8M时表达不增加。IR诱导未成熟大鼠甲状腺自噬，而非成年大鼠甲状腺自噬。

Exposure to ionizing radiation (IR), especially during childhood, is a well-known risk factor for thyroid cancers. To evaluate the radiosensitivity of different age rat thyroid follicular epithelial cells, we analyzed the histological alterations, induction of apoptosis, cell proliferation, expression of DNA damage response molecules, and induction of autophagy in immature (4 W) and adult (8 M) rat thyroid glands up to 72 h after 8Gy X-ray irradiation.IR-induced apoptosis was not detected, and phosphorylated p53 at Ser15 expression and 53BP1 nuclear foci were increased irrespective of age. The vacuolated alteration of the cytoplasm in thyroid follicular cells was observed in 4W. The Ki67-positive cells in 4W were significantly decreased after irradiation. The autophagosomes were observed in 4W cells but not 8M. The expression of LC3-II and p62, and the genes regulated autophagy was increased in 4W but not 8M. IR induced autophagy in immature but not in adult rat thyroid.