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Melatonin Sensitizes Hepatocellular Carcinoma Cells to Chemotherapy Through Long Non-Coding RNA RAD51-AS1-Mediated Suppression of DNA Repair.

ABSTRACT: DNA repair systems are abnormally active in most hepatocellular carcinoma (HCC) cells due to accumulated mutations, resulting in elevated DNA repair capacity and resistance to chemotherapy and radiotherapy. Thus, targeting DNA repair mechanisms is a common treatment approach in HCC to sensitize cancer cells to DNA damage. In this study, we examined the anti-HCC effects of melatonin and elucidated the regulatory mechanisms. The results of functional assays showed that in addition to inhibiting the proliferation, migration, and invasion abilities of HCC cells, melatonin suppressed their DNA repair capacity, thereby promoting the cytotoxicity of chemotherapy and radiotherapy. Whole-transcriptome and gain- and loss-of-function analyses revealed that melatonin induces expression of the long noncoding RNA RAD51-AS1, which binds to RAD51 mRNA to inhibit its translation, effectively decreasing the DNA repair capacity of HCC cells and increasing their sensitivity to chemotherapy and radiotherapy. Animal models further demonstrated that a combination of melatonin and the chemotherapeutic agent etoposide (VP16) can significantly enhance tumor growth inhibition compared with monotherapy. Our results show that melatonin is a potential adjuvant treatment for chemotherapy and radiotherapy in HCC.

SUBMITTER: Chen CC

PROVIDER: S-EPMC6162454 | biostudies-other | 2018 Sep

REPOSITORIES: biostudies-other

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Melatonin Sensitizes Hepatocellular Carcinoma Cells to Chemotherapy Through Long Non-Coding RNA RAD51-AS1-Mediated Suppression of DNA Repair.

Chen Chin-Chuan CC Chen Chi-Yuan CY Wang Shu-Huei SH Yeh Chau-Ting CT Su Shih-Chi SC Ueng Shir-Hwa SH Chuang Wen-Yu WY Hsueh Chuen C Wang Tong-Hong TH

Cancers 20180910 9

DNA repair systems are abnormally active in most hepatocellular carcinoma (HCC) cells due to accumulated mutations, resulting in elevated DNA repair capacity and resistance to chemotherapy and radiotherapy. Thus, targeting DNA repair mechanisms is a common treatment approach in HCC to sensitize cancer cells to DNA damage. In this study, we examined the anti-HCC effects of melatonin and elucidated the regulatory mechanisms. The results of functional assays showed that in addition to inhibiting th ...[more]

PMID: 30201872

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Project description:BackgroundLong non-coding RNAs (lncRNAs) are widely involved in human cancers' progression by regulating tumor cells' various malignant behaviors. MAPKAPK5-AS1 has been recognized as an oncogene in colorectal cancer. However, the biological role of MAPKAPK5-AS1 in hepatocellular carcinoma (HCC) has not been explored.MethodsQuantitative real-time PCR was performed to detect the level of MAPKAPK5-AS1 in HCC tissues and cell lines. The effects of MAPKAPK5-AS1 on tumor growth and metastasis were assessed via in vitro experiments, including MTT, colony formation, EdU, flow cytometry, transwell assays, and nude mice models. The western blotting analysis was carried out to determine epithelial-mesenchymal transition (EMT) markers and AKT signaling. The interaction between MAPKAPK5-AS1, miR-154-5p, and PLAGL2 were explored by luciferase reporter assay and RNA immunoprecipitation. The regulatory effect of HIF-1? on MAPKAPK5-AS1 was evaluated by chromatin immunoprecipitation.ResultsMAPKAPK5-AS1 expression was significantly elevated in HCC, and its overexpression associated with malignant clinical features and reduced survival. Functionally, MAPKAPK5-AS1 knockdown repressed the proliferation, mobility, and EMT of HCC cells and induced apoptosis. Ectopic expression of MAPKAPK5-AS1 contributed to HCC cell proliferation and invasion in vitro. Furthermore, MAPKAPK5-AS1 silencing suppressed, while MAPKAPK5-AS1 overexpression enhanced HCC growth and lung metastasis in vivo. Mechanistically, MAPKAPK5-AS1 upregulated PLAG1 like zinc finger 2 (PLAGL2) expression by acting as an endogenous competing RNA (ceRNA) to sponge miR-154-5p, thereby activating EGFR/AKT signaling. Importantly, rescue experiments demonstrated that the miR-154-5p/PLAGL2 axis mediated the function of MAPKAPK5-AS1 in HCC cells. Interestingly, we found that hypoxia-inducible factor 1? (HIF-1?), a transcript factor, could directly bind to the promoter to activate MAPKAPK5-AS1 transcription. MAPKAPK5-AS1 regulated HIF-1? expression through PLAGL2 to form a hypoxia-mediated MAPKAPK5-AS1/PLAGL2/HIF-1? signaling loop in HCC.ConclusionsOur results reveal a MAPKAPK5-AS1/PLAGL2/HIF-1? signaling loop in HCC progression and suggest that MAPKAPK5-AS1 could be a potential novel therapeutic target of HCC.

Dataset Information

Melatonin Sensitizes Hepatocellular Carcinoma Cells to Chemotherapy Through Long Non-Coding RNA RAD51-AS1-Mediated Suppression of DNA Repair.

Publications

Melatonin Sensitizes Hepatocellular Carcinoma Cells to Chemotherapy Through Long Non-Coding RNA RAD51-AS1-Mediated Suppression of DNA Repair.

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