Functional microRNA high throughput screening reveals miR-9 as a central regulator of liver oncogenesis by affecting the PPARA-CDH1 pathway
Authors: John Souglakos
Dimitrios Iliopoulos
Vassilis Georgoulias
Maria Hatziapostolou
George A Poultsides
Christos Polytarchou
Alexandra Drakaki
Christina Vorvis
Journal: BMC Cancer (2015)
Discipline: CLINICAL MEDICINE
Keywords: Hepatocellular carcinoma; MicroRNAs; HCC invasiveness; MiR-9; MiR-21
Affiliations: Division of Hematology/Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA. ., Laboratory of Tumor Biology, Department of Medical Oncology, University Hospital of Heraklion, Heraklion, Crete, Greece. ., Center for Systems Biomedicine, Division of Digestive Diseases, David Geffen School of Medicine, University of California, Los Angeles, 650 Charles E. Young Dr., CHS 44-133, Los Angeles, CA, 90095-7278, USA. ., Department of Surgery, Stanford School of Medicine, Stanford University, Palo Alto, CA, USA. .

Abstract:  Background: Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths, reflecting the aggressiveness of this type of cancer and the absence of effective therapeutic regimens. MicroRNAs have been involved in the pathogenesis of different types of cancers, including liver cancer. Our aim was to identify microRNAs that have both functional and clinical relevance in HCC and examine their downstream signaling effectors. Methods: MicroRNA and gene expression levels were measured by quantitative real-time PCR in HCC tumors and controls. A TargetScan algorithm was used to identify miR-9 downstream direct targets. Results: A high-throughput screen of the human microRNAome revealed 28 microRNAs as regulators of liver cancer cell invasiveness. MiR-9, miR-21 and miR-224 were the top inducers of HCC invasiveness and also their expression was increased in HCC relative to control liver tissues. Integration of the microRNA screen and expression data revealed miR-9 as the top microRNA, having both functional and clinical significance. MiR-9 levels correlated with HCC tumor stage and miR-9 overexpression induced SNU-449 and HepG2 cell growth, invasiveness and their ability to form colonies in soft agar. Bioinformatics and 3'UTR luciferase analyses identified E-cadherin (CDH1) and peroxisome proliferator-activated receptor alpha (PPARA) as direct downstream effectors of miR-9 activity. Inhibition of PPARA suppressed CDH1 mRNA levels, suggesting that miR-9 regulates CDH1 expression directly through binding in its 3'UTR and indirectly through PPARA. On the other hand, miR-9 inhibition of overexpression suppressed HCC tumorigenicity and invasiveness. PPARA and CDH1 mRNA levels were decreased in HCC relative to controls and were inversely correlated with miR-9 levels. Conclusions: Taken together, this study revealed the involvement of the miR-9/PPARA/CDH1 signaling pathway in HCC oncogenesis. 

Retracted: No

PubPeer comments:
null, 
 March 2021 retraction. Notice found here: https: journals.plos.org plosone article?id=10.1371 journal.pone.0249055  Following the publication of this article [1], concerns were raised regarding Figs 2, 3 and 4. Specifically, * Panel A of Fig 2A appears similar to panel A of Fig 3A and panel A of Fig 4A. * Panels B and C of Fig 3A appear similar to Panels B and C of Fig 4A, respectively. * The GAPDH panels of Fig 2B appear similar to the GAPDH panels of Fig 3B. The authors have indicated that the underlying data for this study cannot be shared due to data confidentiality. The unavailability of the original data underlying the published result is a breach of the PLOS data availability policy. In light of the concerns affecting multiple figure panels that question the validity of these data and the unavailability of the raw data underlying the published results, the PLOS ONE Editors retract this article. MW neither agreed nor disagreed with the retraction. XL, HC, YG, FM, FS, YB, and YL either could not be reached or did not respond directly. I was Peer 1. This paper was found as part of a structured search of 20,000 papers (although not included in the final set), which was published here: https: mbio.asm.org content 7 3 e00809-16. It was reported to the journal in August 2014. I thank the PLOS ONE staff for contacting the authors and retracting the paper. ,