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Parkin facilitates proteasome inhibitor-induced apoptosis via suppression of NF-?B activity in hepatocellular carcinoma.

ABSTRACT: The ubiquitin-proteasome system (UPS) is a tight homeostatic control mechanism of intracellular protein degradation and turnover involved in many human diseases. Proteasome inhibitors were initially developed as anticancer agents with potential benefits in the suppression of tumor growth. However, clinical trials of patients with solid tumors fail to demonstrate the same efficacy of these proteasome inhibitors. Here, we show that Parkin, an E3 ubiquitin ligase, is implicated in tumorigenesis and therapy resistance of hepatocellular carcinoma (HCC), the most common type of primary liver cancer in adults. Lower Parkin expression correlates with poor survival in patients with HCC. Ectopic Parkin expression enhances proteasome inhibitor-induced apoptosis and tumor suppression in HCC cells in vitro and in vivo. In contrast, knockdown of Parkin expression promotes apoptosis resistance and tumor growth. Mechanistically, Parkin promotes TNF receptor-associated factor (TRAF) 2 and TRAF6 degradation and thus facilitates nuclear factor-kappa-B (NF-?B) inhibition, which finally results in apoptosis. These findings reveal a direct molecular link between Parkin and protein degradation in the control of the NF-?B pathway and may provide a novel UPS-dependent strategy for the treatment of HCC by induction of apoptosis.

SUBMITTER: Zhang X

PROVIDER: S-EPMC6763437 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Parkin facilitates proteasome inhibitor-induced apoptosis via suppression of NF-κB activity in hepatocellular carcinoma.

Zhang Xiaolan X Lin Chun C Song Junwei J Chen Han H Chen Xuhong X Ren Liangliang L Zhou Zhongqiu Z Pan Jinyuan J Yang Zhenjun Z Bao Wenhao W Ke Xueping X Yang Jianan J Liang Yingying Y Huang Hongbiao H Tang Daolin D Jiang Lili L Liu Jinbao J

Cell death & disease 20190926 10

The ubiquitin-proteasome system (UPS) is a tight homeostatic control mechanism of intracellular protein degradation and turnover involved in many human diseases. Proteasome inhibitors were initially developed as anticancer agents with potential benefits in the suppression of tumor growth. However, clinical trials of patients with solid tumors fail to demonstrate the same efficacy of these proteasome inhibitors. Here, we show that Parkin, an E3 ubiquitin ligase, is implicated in tumorigenesis and ...[more]

PMID: 31558697

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Project description:BackgroundMultiple myeloma (MM) is an incurable hematological malignancy. Although proteasome inhibitors and immunomodulators have significantly improved patient outcomes, some patients respond poorly to treatment and almost all patients will relapse. Mechanisms of proteasome inhibitor resistance in multiple myeloma have not been fully elucidated. ZHX2 is a transcription regulator degraded via proteasome and presents both oncogenic or tumor suppressive effect in different cancers, however, it is still unknown that the role of ZHX2 in myeloma. In this study, we aim to demonstrate the effect and mechanism of ZHX2 on proteasome inhibitor resistance in MM.MethodsGSE24080 gene expression profile datasets from Gene Expression Omnibus (GEO) were analyzed to evaluate the relationship between ZHX2 expression level and survival in MM. Expression of ZHX2 in human MM cell lines at baseline and after bortezomib (BTZ) treatment was determined by Western blotting (WB). The proliferation and apoptosis rate of MM cells treated with BTZ after the knockdown of ZHX2 were analyzed by flow cytometry. Nuclear translocation of NF-κB after the knockdown of ZHX2 was evaluated by WB and immunofluorescence, and the expression of NF-κB target genes was measured by real-time quantitative PCR. Co-immunoprecipitation (Co-IP) and WB were used to detect the interaction of ZHX2 with NF-κB.ResultsWe found that higher ZHX2 expression was correlated with poorer clinical outcomes of patients. In addition, ZHX2 expression was relatively higher in RPMI-8226 and MM.1S cell lines and the level of ZHX2 protein was upregulated after BTZ treatment. Knockdown of ZHX2 significantly enhanced the sensitivity of MM cells to BTZ, inhibited nuclear translocation of NF-κB, and reduced mRNA expression of NF-κB target genes. It was also revealed that ZHX2 directly binds to NF-κB.ConclusionOur study showed that ZHX2 can promote proteasome inhibitor resistance in MM cells by regulating the nuclear translocation of NF-κB.

Dataset Information

Parkin facilitates proteasome inhibitor-induced apoptosis via suppression of NF-?B activity in hepatocellular carcinoma.

Publications

Parkin facilitates proteasome inhibitor-induced apoptosis via suppression of NF-κB activity in hepatocellular carcinoma.

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