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      miR- 26a Sensitizes Melanoma Cells To Dabrafenib Via Targeting HMGB1-Dependent Autophagy Pathways

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          Abstract

          Background

          Melanoma is known as the most aggressive and lethal type of cutaneous cancer due to its rapid development of drug resistance to chemotherapy drugs.

          Methods

          In our study, we conducted a variety of studies, including quantitative PCR, Western blot, and autophagy and apoptosis assays to investigate the involvement of miR-26a and HMGB1 in modulation of dabrafenib sensitivity in human melanoma cell lines.

          Results

          Our studies revealed that the expressions of miR-26a and HMGB1 were altered in two melanoma cell lines after dabrafenib treatment. Additionally, dabrafenib caused autophagy in melanoma and this autophagic process was regulated by miR-26a via modifying HMGB1 expression. Furthermore, silencing HMGB1-inhibited autophagy induced by dabrafenib in melanoma cells. Last, we verified that treatment with a miR-26a mimic and HMGB1 shRNA could increase the efficacy of dabrafenib in melanoma cells.

          Conclusion

          Taken together, we showed that miR-26a is involved in the regulation of dabrafenib efficacy via a HMGB1-dependent autophagy pathway in melanoma cells. These results shed light on a novel treatment for conventional dabrafenib-based chemotherapy for melanoma.

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          Most cited references 28

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          PAMP s and DAMP s: signal 0s that spur autophagy and immunity

          Summary Pathogen‐associated molecular pattern molecules (PAMPs) are derived from microorganisms and recognized by pattern recognition receptor (PRR)‐bearing cells of the innate immune system as well as many epithelial cells. In contrast, damage‐associated molecular pattern molecules (DAMPs) are cell‐derived and initiate and perpetuate immunity in response to trauma, ischemia, and tissue damage, either in the absence or presence of pathogenic infection. Most PAMPs and DAMPs serve as so‐called ‘Signal 0s’ that bind specific receptors [Toll‐like receptors, NOD‐like receptors, RIG‐I‐like receptors, AIM2‐like receptors, and the receptor for advanced glycation end products (RAGE)] to promote autophagy. Autophagy, a conserved lysosomal degradation pathway, is a cell survival mechanism invoked in response to environmental and cellular stress. Autophagy is inferred to have been present in the last common eukaryotic ancestor and only to have been lost by some obligatory intracellular parasites. As such, autophagy represents a unifying biology, subserving survival and the earliest host defense strategies, predating apoptosis, within eukaryotes. Here, we review recent advances in our understanding of autophagic molecular mechanisms and functions in emergent immunity.
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            Meta-analysis of phase II cooperative group trials in metastatic stage IV melanoma to determine progression-free and overall survival benchmarks for future phase II trials.

            Objective tumor response rates observed in phase II trials for metastatic melanoma have historically not provided a reliable indicator of meaningful survival benefits. To facilitate using overall survival (OS) or progression-free survival (PFS) as an endpoint for future phase II trials, we evaluated historical data from cooperative group phase II trials to attempt to develop benchmarks for OS and PFS as reference points for future phase II trials. Individual-level and trial-level data were obtained for patients enrolled onto 42 phase II trials (70 trial arms) that completed accrual in the years 1975 through 2005 and conducted by Southwest Oncology Group, Eastern Cooperative Oncology Group, Cancer and Leukemia Group B, North Central Cancer Treatment Group, and the Clinical Trials Group of the National Cancer Institute of Canada. Univariate and multivariate analyses were performed to identify prognostic variables, and between-trial(-arm) variability in 1-year OS rates and 6-month PFS rates were examined. Statistically significant individual-level and trial-level prognostic factors found in a multivariate survival analysis for OS were performance status, presence of visceral disease, sex, and whether the trial excluded patients with brain metastases. Performance status, sex, and age were statistically significant prognostic factors for PFS. Controlling for these prognostic variables essentially eliminated between-trial variability in 1-year OS rates but not in 6-month PFS rates. Benchmarks are provided for 1-year OS or OS curves that make use of the distribution of prognostic factors of the patients in the phase II trial. A similar benchmark for 6-month PFS is provided, but its use is more problematic because of residual between-trial variation in this endpoint.
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              MiR-26a inhibits cell growth and tumorigenesis of nasopharyngeal carcinoma through repression of EZH2.

              Several microRNAs (miRNA) have been implicated in nasopharyngeal carcinoma (NPC), a highly invasive and metastatic cancer that is widely prevalent in southern China. In this study, we report that microRNA miR-26a is commonly downregulated in NPC specimens and NPC cell lines with important functional consequences. Ectopic expression of miR-26a dramatically suppressed cell proliferation and colony formation by inducing G(1)-phase cell-cycle arrest. We found that miR-26a strongly reduced the expression of EZH2 oncogene in NPC cells. Similar to the restoring miR-26 expression, EZH2 downregulation inhibited cell growth and cell-cycle progression, whereas EZH2 overexpression rescued the suppressive effect of miR-26a. Mechanistic investigations revealed that miR-26a suppressed the expression of c-myc, the cyclin D3 and E2, and the cyclin-dependent kinase CDK4 and CDK6 while enhancing the expression of CDK inhibitors p14(ARF) and p21(CIP1) in an EZH2-dependent manner. Interestingly, cyclin D2 was regulated by miR-26a but not by EZH2, revealing cyclin D2 as another direct yet mechanistically distinct target of miR-26a. In clinical specimens, EZH2 was widely overexpressed and its mRNA levels were inversely correlated with miR-26a expression. Taken together, our results indicate that miR-26a functions as a growth-suppressive miRNA in NPC, and that its suppressive effects are mediated chiefly by repressing EZH2 expression. © 2011 AACR.
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                Author and article information

                Journal
                Drug Des Devel Ther
                Drug Des Devel Ther
                DDDT
                dddt
                Drug Design, Development and Therapy
                Dove
                1177-8881
                29 October 2019
                2019
                : 13
                : 3717-3726
                Affiliations
                [1 ]Department of Dermatology, First Hospital of Jilin University , Changchun, Jilin 130021, People’s Republic of China
                [2 ]Department of Dermatology, The First Affiliated Hospital of Fujian Medical University , Fuzhou, Fujian 350005, People’s Republic of China
                Author notes
                Correspondence: Chao Ji Department of Dermatology, The First Affiliated Hospital of Fujian Medical University , Fuzhou, Fujian350005, People’s Republic of China Email surpassing.ji@gmail.com
                Bo Cheng Department of Dermatology, The First Affiliated Hospital of Fujian Medical University , Fuzhou, Fujian350005, People’s Republic of China Email chengbo_fjmu1@163.com
                [*]

                These authors contributed equally to this work

                Article
                225671
                10.2147/DDDT.S225671
                6825511
                © 2019 Yu et al.

                This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms ( https://www.dovepress.com/terms.php).

                Page count
                Figures: 6, References: 44, Pages: 10
                Categories
                Original Research

                Pharmacology & Pharmaceutical medicine

                apoptosis, melanoma, autophagy, dabrafenib, hmgb1, mir-26a

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