ABSTRACT
Objective:To validate the effect of TUT4 on the radiosensitivity of esophageal epithelial cells (HEEC) by regulating the uridylation of miR132/212 clusters.Methods:The expression of TUT4 in HEEC at 0, 6, 18, 24 and 48 h after 0, 2, 4, 6 and 8 Gy X-ray irradiation was detected by PCR. The HEEC cells were divided into four groups: NC group, shTUT4 group, 6 Gy group, and 6 Gy+ shTUT4 group. The effects of TUT4 on cell radiosensitivity, cell proliferation, cell cycle, mitochondrial damage, and oxygen free radical production were detected respectively. The effect of down-regulated TUT4 expression on miR132/212 uridylation was detected by RT-PCR, and the radiosensitivity of HEEC with overexpression of miR132/212 or miR132/212+ UUU was detected by clone formation and proliferation assay, respectively. Proliferation assay was performed to detect the proliferation of HEEC when TUT4 expression was down-regulated and miR132/212 or miR132/212+ UUU was overexpressed.Results:TUT4 expression increased after different doses of X-ray irradiation ( t=12.84, 62.06, 27.86, 32.43, P<0.05). Downregulation of TUT4 expression increased the radiosensitivity of HEEC ( t=13.2, 5.85, 7.31, P<0.05) with a SER D0of 1.41 and D0=0.79, Dq=1.61, SF2=0.47. Compared with 6 Gy group, cell proliferation in 6 Gy+ shTUT4 group was decreased ( t=7.12, 13.63, P<0.05), cells in S phase were increased ( t=11.98, P<0.05), mitochondrial damage was increased ( t=11.98, P<0.05), and ROS level was increased ( t=15.65, P<0.05). Down-regulation of TUT4 expression increased miR132/212 expression and decreased miR132/212+ UUU expression ( t=27.90, 60.99, P<0.05). Overexpression of miR132/212 increased the radiosensitivity of HEEC, and overexpression of miR132/212+ UUU decreased the radiosensitivity of HEEC, with SER D0 of 1.20 and 0.71, respectively. Cell proliferation of shTUT4 + miR132/212 group waslower than that of shTUT4 group( t=4.76, 7.65, P<0.05), and cell proliferation of shTUT4 + miR132/212+ UUU group was higher than that of shTUT4 ( t=7.22, P<0.05). Conclusions:X-ray irradiation increased the expression of TUT4 in HEEC, and the down-regulation of TUT4 reduced HEEC radiosensitivity and radiation damage, where the uridylation of miR132/212 was involved in.