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A low dose of AZD8055 enhances radiosensitivity of nasopharyngeal carcinoma cells by activating autophagy and apoptosis.

ABSTRACT: Activation of the PI3K/mTOR pathways is significantly correlated with a poor prognosis in nasopharyngeal carcinoma (NPC). Inhibition of these pathways was reported to be effective in restoring radiosensitivity. In this study, the activity of the novel ATP-competitive, orally bioavailable mTOR inhibitor AZD8055 was found to inhibit the phosphorylated mTOR and NPC cells proliferation. The IC50 doses in CNE1 and CNE2 cell lines were 60 and 100 nanomolar, respectively. AZD8055 significantly enhanced the inhibitions of cell growth and colony formation induced by irradiation (P < 0.05 for all). AZD8055 at the IC50 doses prolonged G2/M arrest (P < 0.05) and promoted the apoptosis (P < 0.01) induced by irradiation and autophagy in NPC cells. Blocking autophagy weaken the cell growth inhibition and decreased apoptosis induced by AZD8055 combined with irradiation. Treatment with AZD8055 at 5, 10 and 20 mg/kg/d significantly enhanced NPC cell radiosensitivity in vivo and significantly induced apoptosis and autophagy in tumor tissues, Neither 5 nor 20 mg/kg/d AZD8055 induced significantly pro-apoptosis bax expressions in mouse livers and kidneys. 5 mg/kg/d produced good radiosensitivity but had little impact on body weight. We concluded that AZD8055 was a promising candidate radiosensitizer for NPC.

SUBMITTER: Chang L

PROVIDER: S-EPMC6780664 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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A low dose of AZD8055 enhances radiosensitivity of nasopharyngeal carcinoma cells by activating autophagy and apoptosis.

Chang Lihong L Huang Zizhen Z Li Shuaixiang S Yao Zhouzhou Z Bao Hongwei H Wang Zhiyuan Z Li Xia X Chen Xiaohong X Huang Jiancong J Zhang Gehua G

American journal of cancer research 20190901 9

Activation of the PI3K/mTOR pathways is significantly correlated with a poor prognosis in nasopharyngeal carcinoma (NPC). Inhibition of these pathways was reported to be effective in restoring radiosensitivity. In this study, the activity of the novel ATP-competitive, orally bioavailable mTOR inhibitor AZD8055 was found to inhibit the phosphorylated mTOR and NPC cells proliferation. The IC50 doses in CNE1 and CNE2 cell lines were 60 and 100 nanomolar, respectively. AZD8055 significantly enhanced ...[more]

PMID: 31598395

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Project description:BackgroundRecurrence due to the development of radioresistance remains a major challenge in the clinical management of nasopharyngeal carcinoma. The objective of this study was to increase the sensitivity of nasopharyngeal carcinoma cells to ionizing radiation by enhancing oxidative stress and ferroptosis caused by disrupting the mitochondrial anti-oxidant enzyme system.MethodsOxidative stress cell model was constructed by SOD2 knockdown using shRNA. The expression and activity of DHODH was suppressed by siRNA and brequinar in SOD2 depleted cells. Protein levels were determined by western blotting and ferroptosis was assessed by C11 BODIPY and malondialdehyde assay. Cell viability was evaluated using CCK-8 assay while radiotoxicity was assessed by colony formation assay. Cellular ATP level was determined by ATP assay kits, ROS was determined by DCFD and DHE, while mitochondrial oxygen consumption was determined by seahorse assay. Data were analyzed by two-tailed independent t-test.ResultsRadiation upregulated SOD2 expression and SOD2 depletion increased cellular O2.-, malondialdehyde, and the fluorescence intensity of oxidized C11 BODIPY. It also resulted in mitochondrial damage. Its depletion decreased colony formation both under ionizing and non-ionizing radiation conditions. The ferroptosis inhibitor, deferoxamine, rescued cell viability and colony formation in SOD2 depleted cells. Cellular level of malondialdehyde, fluorescence intensity of oxidized C11 BODIPY, O2.- level, ATP, and mitochondrial oxygen consumption decreased following DHODH inhibition in SOD2 depleted cells. Cell viability and colony formation was rescued by DHODH inhibition in SOD2 depleted cells.ConclusionInducing oxidative stress by SOD2 inhibition sensitized nasopharyngeal carcinoma cells to ionizing radiation via ferroptosis induction. This was found to be dependent on DHODH activity. This suggests that DHODH inhibitors should be used with caution during radiotherapy in nasopharyngeal carcinoma patients.

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A low dose of AZD8055 enhances radiosensitivity of nasopharyngeal carcinoma cells by activating autophagy and apoptosis.

Publications

A low dose of AZD8055 enhances radiosensitivity of nasopharyngeal carcinoma cells by activating autophagy and apoptosis.

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