Abstract
Homologous to the E6-associated protein carboxyl terminus domain containing 3 (HECTD3) has been reported to play a role in carcinogenesis. Here, we explored the role of HECTD3 in regulating the radiation resistance of glioma, and the underlying mechanism. HECTD3 expressions in glioma tissues were assessed using Western blotting, quantitative reverse transcription (qRT)-polymerase chain reaction (PCR) and immunohistochemistry. Glioma cells were exposed to 2-, 4-, 6- or 8-Gy X-ray to mimic the radiation treatment. Cell count kit-8 (CCK-8), clone formation assay, flow cytometry assay, transwell chambers and animal assay were used to test cell viability, apoptosis, migration, invasiveness and tumourigenesis, respectively. HECTD3 expression was increased in glioma tissues, especially from patients with radiation resistance. Knockdown of HECTD3 promoted cell apoptosis and inhibited cell viability under the condition of 8-Gy X-ray, as well as suppressed cell migration and invasiveness. In mechanism, HECTD3 positively regulated ZEB1 (zinc finger E-box binding hemeobox 1) expression through regulating the ubiquitination of liver kinase B1 (LKB1) protein. Overexpression of ZEB1 significantly abolished the effects of HECTD3 downregulation in inhibiting the radiation resistance and migration of glioma cells. Moreover, downregulation of HECTD3 further enhanced the anti-tumour effect of X-ray on glioma growth in vivo. In conclusion, HECTD3 was overexpressed in glioma patients with radiation resistance. Knockdown of HECTD3 sensitized glioma cells to radiation and inhibited cell migration by downregulating ZEB1 expression via regulating the ubiquitination of LKB1 protein. This study reveals that HECTD3 might be a potent target to enhance the radiation sensitivity of glioma.