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Synergistic inhibition of autophagy and neddylation pathways as a novel therapeutic approach for targeting liver cancer.

ABSTRACT: Liver cancer is the second-most frequent cause of cancer death in the world and is highly treatment resistant. We reported previously that inhibition of neddylation pathway with specific NAE inhibitor MLN4924, suppressed the malignant phenotypes of liver cancer. However, during the process, MLN4924 induces pro-survival autophagy as a mechanism of drug resistance. Here, we report that blockage of autophagy with clinically-available autophagy inhibitors (e.g. chloroquine) significantly enhanced the efficacy of MLN4924 on liver cancer cells by triggering apoptosis. Mechanistically, chloroquine enhanced MLN4924-induced up-regulation of pro-apoptotic proteins (e.g. NOXA) and down-regulation of anti-apoptotic proteins. Importantly, the down-regulation of NOXA expression via siRNA silencing substantially attenuated apoptosis of liver cancer cells. Further mechanistic studies revealed that blockage of autophagy augmented MLN4924-induced DNA damage and reactive oxygen species (ROS) generation. The elimination of DNA damage or blockage of ROS production significantly reduced the expression of NOXA, and thereby attenuated apoptosis and reduced growth inhibition of liver cancer cells. Moreover, blockage of autophagy enhanced the efficacy of MLN4924 in an orthotopic model of human liver cancer, with induction of NOXA and apoptosis in tumor tissues. These findings provide important preclinical evidence for clinical investigation of synergistic inhibition of neddylation and autophagy in liver cancer.

SUBMITTER: Chen P

PROVIDER: S-EPMC4496198 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Synergistic inhibition of autophagy and neddylation pathways as a novel therapeutic approach for targeting liver cancer.

Chen Ping P Hu Tao T Liang Yupei Y Jiang Yanan Y Pan Yongfu Y Li Chunjie C Zhang Ping P Wei Dongping D Li Pei P Jeong Lak Shin LS Chu Yiwei Y Qi Hui H Yang Meng M Hoffman Robert M RM Dong Ziming Z Jia Lijun L

Oncotarget 20150401 11

Liver cancer is the second-most frequent cause of cancer death in the world and is highly treatment resistant. We reported previously that inhibition of neddylation pathway with specific NAE inhibitor MLN4924, suppressed the malignant phenotypes of liver cancer. However, during the process, MLN4924 induces pro-survival autophagy as a mechanism of drug resistance. Here, we report that blockage of autophagy with clinically-available autophagy inhibitors (e.g. chloroquine) significantly enhanced th ...[more]

PMID: 25797246

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Project description:We have used human umbilical vein endothelial cell line (HUVEC) as a model to investigate the effect of ultrasound (US) activated micro-bubbles on sensitizing the tumour response to radiation and to check the implication of this approach on gene expression. The use of micro-bubbles in cancer therapy is a novel approach that is being recently investigated, and patterns of gene expressions were not yet characterized. Gene analysis has identified about 19,264 genes; where, 239 – 517 genes have shown more than two folds up-regulation in response to the different treatments. This included a number of genes that are known to be involved in apoptosis and ceramide-induced apoptosis pathways, such as Sphingomyelin phosphodiesterase 2, neutral sphingomyelinase (SMPD2), sphingomyelin phosphodiesterase 1, acid lysosomal (ASM; SMPD1), UDP-galactose ceramide galactosyltransferase (UGT8), cytochrome c oxidase (COX6B1), Caspase-9 and mitogen-activated protein kinase kinase 1 (MAP2K1). To verify these results, we have performed Real time RT-PCR, which indicated an up-regulation that ranged from 2 to 200 folds, specifically in the combined treatment of US, 3.3% micro-bubbles and 8 Gy. The observed higher levels of expression of UGT8, SMPD2 and Caspase 9-alpha when compared to the control or to radiation only indicated the involvement of ceramide, which possibly induces apoptosis . These results support the hypothesis that micro-bubbles play a role in increasing sensitization to radiation, and can prove to be an effective cancer therapeutic approach. Gene analysis has identified about 19,264 genes; where, 239 – 517 genes have shown more than two folds up-regulation in response to the different treatments. This included a number of genes that are known to be involved in apoptosis and ceramide-induced apoptosis pathways, such as Sphingomyelin phosphodiesterase 2, neutral sphingomyelinase (SMPD2), sphingomyelin phosphodiesterase 1, acid lysosomal (ASM; SMPD1), UDP-galactose ceramide galactosyltransferase (UGT8), cytochrome c oxidase (COX6B1), Caspase-9 and mitogen-activated protein kinase kinase 1 (MAP2K1). To verify these results, we have performed Real time RT-PCR, which indicated an up-regulation that ranged from 2 to 200 folds, specifically in the combined treatment of US, 3.3% micro-bubbles and 8 Gy. The observed higher levels of expression of UGT8, SMPD2 and Caspase 9-alpha when compared to the control or to radiation only indicated the involvement of ceramide, which possibly induces apoptosis . These results support the hypothesis that micro-bubbles play a role in increasing sensitization to radiation, and can prove to be an effective cancer therapeutic approach.

Dataset Information

Synergistic inhibition of autophagy and neddylation pathways as a novel therapeutic approach for targeting liver cancer.

Publications

Synergistic inhibition of autophagy and neddylation pathways as a novel therapeutic approach for targeting liver cancer.

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