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      Catalpol-mediated microRNA-34a suppresses autophagy and malignancy by regulating SIRT1 in colorectal cancer

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      , ,
      Oncology Reports
      D.A. Spandidos
      colorectal cancer, catalpol, autophagy, miR-34a, SIRT1

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          Abstract

          Colorectal cancer (CRC) is one of the most common digestive tract tumors worldwide. Catalpol exerts inhibitory effects on the progression of several cancer types by regulating microRNAs (miRs). However, the precise role and carcinostatic mechanism of catalpol on CRC cells are poorly understood which limits the application of catalpol treatment. In the present study, miR-34a and sirtuin 1 (SIRT1) expression levels were detected in CRC tissues and CRC cell lines by RT-qPCR. Computational software analysis, luciferase assays and western blotting were used to demonstrate the downstream target of miR-34a in CRC cells. Effects of catalpol on cell viability, apoptosis, autophagic flux and the miR-34a/SIRT1 axis in the CRC cells were assessed by CCK-8 assay, flow cytometry, electron microscopy and western blotting, respectively. Whether the miR-34a/SIRT1 axis participated in catalpol-mediated autophagy and apoptosis was investigated. The effects of catalpol on the miR-34a/SIRT1 axis and malignant behavior were evaluated in a rat model of azoxymethane (AOM)-induced CRC. It was revealed that miR-34a expression levels were significantly decreased while SIRT1 was overexpressed in most of the CRC tissues and all the CRC cell lines. Clinically, a low level of miR-34a was correlated with poor clinicopathological characteristics in CRC patients. Catalpol reduced cell viability, suppressed autophagy, promoted apoptosis, and regulated the expression of SIRT1 by inducing miR-34a in vitro and in vivo. The autophagy-inhibiting effect of catalpol may be a mechanism to promote apoptosis of CRC cells. miR-34a mimic transfection resulted in autophagy-suppressive activity similar to that of catalpol, while the miR-34a inhibitor attenuated the antiautophagic effects of catalpol. In conclusion, miR-34a is involved in regulating catalpol-mediated autophagy and malignant behavior by directly inhibiting SIRT1 in CRC.

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          Most cited references21

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          Long non-coding RNA HNF1A-AS1 mediated repression of miR-34a/SIRT1/p53 feedback loop promotes the metastatic progression of colon cancer by functioning as a competing endogenous RNA.

          In recent years, accumulating evidence indicates that long noncoding RNAs (lncRNAs) have emerged as powerful influence factors in the progression of multiple malignancies. Dysregulation of lncRNA HNF1A-antisense 1 (HNF1A-AS1) has been reported in many types of human cancers, and studies on HNF1A-AS1 function in cancers revealed that HNF1A-AS1could act as either oncogene or tumor suppressor. Nevertheless, the functional involvement of HNF1A-AS1 in colon cancer remains unknown. In this study, we reported that HNF1A-AS1 was frequently upregulated in colon cancer tissues and associated with poor prognosis. Upregulated HNF1A-AS1 promoted colon cancer cell viability, migration and invasion both in vitro and in vivo. HNF1A-AS1 silencing impaired tumor growth and metastasis in xenograft model assay. Moreover, HNF1A-AS1 functioned as an oncogene in metastasis of colon cancer in part through serving as a competing endogenous RNA to modulate miRNA-34a expression, subsequently with repression of miR-34a/SIRT1/p53 feedback loop and activation of canonical Wnt signaling pathway. Our results demonstrated that HNF1A-AS1 mediated the metastatic progression of colon cancer in part through miR-34a/p53 signaling axis, and established its candidacy as a new prognostic biomarker and a potential novel therapeutic target.
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            Role of Autophagy in Cancer: Management of Metabolic Stress

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              miR-34a mediates oxaliplatin resistance of colorectal cancer cells by inhibiting macroautophagy via transforming growth factor-β/Smad4 pathway

              AIM To investigate whether microRNA (miR)-34a mediates oxaliplatin (OXA) resistance of colorectal cancer (CRC) cells by inhibiting macroautophagy via the transforming growth factor (TGF)-β/Smad4 pathway. METHODS miR-34a expression levels were detected in CRC tissues and CRC cell lines by quantitative real-time polymerase chain reaction. Computational search, functional luciferase assay and western blotting were used to demonstrate the downstream target of miR-34a in CRC cells. Cell viability was measured with Cell Counting Kit-8. Apoptosis and macroautophagy of CRC cells were analyzed by flow cytometry and transmission electron microscopy, and expression of beclin I and LC3-II was detected by western blotting. RESULTS Expression of miR-34a was significantly reduced while expression of TGF-β and Smad4 was increased in CRC patients treated with OXA-based chemotherapy. OXA treatment also resulted in decreased miR-34a levels and increased TGF-β and Smad4 levels in both parental cells and the OXA-resistant CRC cells. Activation of macroautophagy contributed to OXA resistance in CRC cells. Expression levels of Smad4 and miR-34a in CRC patients had a significant inverse correlation and overexpressing miR-34a inhibited macroautophagy activation by directly targeting Smad4 through the TGF-β/Smad4 pathway. OXA-induced downregulation of miR-34a and increased drug resistance by activating macroautophagy in CRC cells. CONCLUSION miR-34a mediates OXA resistance of CRC by inhibiting macroautophagy via the TGF-β/Smad4 pathway.
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                Author and article information

                Journal
                Oncol Rep
                Oncol. Rep
                Oncology Reports
                D.A. Spandidos
                1021-335X
                1791-2431
                April 2020
                07 February 2020
                07 February 2020
                : 43
                : 4
                : 1053-1066
                Affiliations
                Department of General Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
                Author notes
                Correspondence to: Dr Lei Yao, Department of General Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China, E-mail: oppoigod@ 123456sina.com
                Article
                or-43-04-1053
                10.3892/or.2020.7494
                7057773
                32323786
                69629b0d-5766-4b47-98c7-e606efad482e
                Copyright: © Qiao et al.

                This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

                History
                : 31 July 2019
                : 13 December 2019
                Categories
                Articles

                colorectal cancer,catalpol,autophagy,mir-34a,sirt1
                colorectal cancer, catalpol, autophagy, mir-34a, sirt1

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