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SIRT1 deacetylated and stabilized XRCC1 to promote chemoresistance in lung cancer.

ABSTRACT: Chemoresistance is one of the most important challenges in the clinical management of lung cancer. SIRT1 is a NAD dependent protein deacetylase and implicated in diverse cellular processes such as DNA damage repair, and cancer progression. SIRT1 is upregulated in chemoresistant lung cancer cells, genetic knockdown or chemical inhibition of SIRT1 reversed chemoresistance by enhancing DNA damage and apoptosis activation, accompanied with XRCC1 degradation. E3 ligase ?-TrCP catalyzed the poly-ubiquitination of XRCC1 to promote its proteasome-dependent degradation. SIRT1 bound and deacetylated XRCC1 at lysine K260, K298 and K431, preventing it from ?-TrCP-dependent ubiquitination. Mutations of these three lysine sites in XRCC1 abrogated the interaction with ?-TrCP and prolonged the half-life of XRCC1 protein. Here, we describes SIRT1 confers chemoresistance to lung cancer cells by deacetylating and stabilizing XRCC1. Therefore, targeting SIRT1 might be a new strategy to manage the chemoresistance of lung cancer, and probably other cancers.

SUBMITTER: Yousafzai NA

PROVIDER: S-EPMC6494911 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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SIRT1 deacetylated and stabilized XRCC1 to promote chemoresistance in lung cancer.

Yousafzai Neelum Aziz NA Zhou Qiyin Q Xu Wenxia W Shi Qiqi Q Xu Jinye J Feng Lifeng L Chen Hui H Shin Vivian Yvonne VY Jin Hongchuan H Wang Xian X

Cell death & disease 20190501 5

Chemoresistance is one of the most important challenges in the clinical management of lung cancer. SIRT1 is a NAD dependent protein deacetylase and implicated in diverse cellular processes such as DNA damage repair, and cancer progression. SIRT1 is upregulated in chemoresistant lung cancer cells, genetic knockdown or chemical inhibition of SIRT1 reversed chemoresistance by enhancing DNA damage and apoptosis activation, accompanied with XRCC1 degradation. E3 ligase β-TrCP catalyzed the poly-ubiqu ...[more]

PMID: 31043584

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Project description:Chemotherapy is the main treatment for human cancers including gastric cancer. However, in response to chemotherapeutic drugs, tumor cells can develop drug resistance by reprogramming intracellular metabolic and epigenetic networks to maintain their intrinsic homeostasis. Previously, we have established cisplatin-resistant gastric cancer cells as a drug resistant model, and elucidated the XRCC1 as the core DNA repair mechanism of drug resistance. This study investigated the regulation of XRCC1 by lysine demethylase 5B (KDM5B) in drug resistance. We found that the methylation level of H3K4 decreased significantly in drug-resistant cells. The chemical inhibitor of H3K4 demethylases, JIB-04, restored the methylation of H3K4 and blocked the co-localization of XRCC1 and ?H2AX, eventually improved drug sensitivity. We further found that the expression level of KDM5B increased significantly in drug-resistant cells. Knockdown of KDM5B increased the methylation level of H3K4 and blocked the localization of XRCC1 to the DNA damage site, leads to increased drug sensitivity. In the sensitive cells, overexpression of KDM5B suppressed H3K4 methylation levels, which resulted to resistance to cisplatin. Moreover, we found that the posttranslational modification of KDM5B is responsible for its high expression in drug-resistant cells. Through mass spectrometry screening and co-immunoprecipitation validation, we found that the molecular chaperone HSP90 forms a complex with KDM5B in drug resistance cells. Interestingly, HSP90 inhibitor 17-AAG induced KDM5B degradation in a time-and-dose-dependent manner, indicating that HSP90 protected KDM5B from protein degradation. Targeting inhibition of HSP90 and KDM5B reversed drug resistance both in vitro and in vivo. Taken together, molecular chaperon HSP90 interacted with KDM5B to protect it from ubiquitin-dependent proteasomal degradation. Increased KDM5B demethylated H3K4 and facilitated the recruitment of XRCC1 to repair damaged DNA. Therefore, inhibition of HSP90 or KDM5B represented a novel approach to reverse chemoresistance in human cancers.

Project description:BackgroundNicotinamide N-methyltransferase (NNMT) is overexpressed in various human tumors and involved in the development and progression of several carcinomas. In breast cancer, NNMT was found to be overexpressed in several cell lines. However, the clinical relevance of NNMT in breast cancer is not yet clear.MethodsNNMT expression in breast carcinoma was examined by immunohistochemistry, and then, its relationship with patient clinicopathological characteristics was analyzed. The effects of NNMT on chemoresistance in breast cancer cells were assessed by cell viability, colony formation, and apoptosis assay. The NNMT, SIRT1, p53, and acetyl-p53 proteins, which are involved in NNMT-related chemoresistance, were examined by Western blotting. The SIRT1 mRNA was examined by real-time PCR, and its activity was measured by using the SIRT1 deacetylase fluorometric reagent kit.ResultsNNMT expression was significantly higher (53.9%) in breast carcinoma than in paracancerous tissues (10.0%) and breast hyperplasia (13.3%). A high level of NNMT expression correlated with poor survival and chemotherapy response in breast cancer patients who received chemotherapy. Ectopic overexpression of NNMT significantly inhibited the apoptotic cell death and suppression of colony formation induced by adriamycin and paclitaxel. Mechanistic studies revealed that NNMT overexpression increased SIRT1 expression and promoted its activity. Either inhibition of SIRT1 by EX527 or knockdown of SIRT1 by siRNA could reverse NNMT-mediated resistance to adriamycin and paclitaxel, which suggests that SIRT1 plays a critical role in NNMT-related chemoresistance in breast cancer.ConclusionsThe results of this study demonstrate a novel correlation between the NNMT expression level and patient survival, suggesting that NNMT has the potential to become a new prognostic biomarker to predict the treatment outcomes of the clinical chemotherapy in breast cancer. Moreover, targeting NNMT or downstream SIRT1 may represent a new therapeutic approach to improve the efficacy of breast cancer chemotherapy.

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SIRT1 deacetylated and stabilized XRCC1 to promote chemoresistance in lung cancer.

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SIRT1 deacetylated and stabilized XRCC1 to promote chemoresistance in lung cancer.

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