title: miRNA-320a inhibits tumor proliferation and invasion by targeting c-Myc in human hepatocellular carcinoma.
abstract: BACKGROUND
  Downregulated expression levels of microRNA-320a (miR-320a) were found in primary breast cancers and colorectal cancer. Previous findings indicated that miRNA-320a may involve in the cancer development. In this study, we explored the roles of miR-320a by targeting c-Myc in the tumor growth of hepatocellular carcinoma (HCC).
  
  
  METHODS
  Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was performed to detect the expression of miR-320a in 50 HCC tissues and four HCC cells. Luciferase reporter assay was conducted to confirm the direct downstream target of miR-320a in HEK-293 cells. The effect of miR-320a on endogenous c-Myc expression was investigated by transfecting miR-320a mimics into HepG2 and QGY-7703 cell lines. The c-Myc and miR-320a expressions were analyzed by immunohistochemistry (IHC) and qRT-PCR in the same HCC tissues. Furthermore, the biological functional correlation of miR-320a with c-Myc was determined by studying the effect of miR-320a mimics or c-Myc small interfering RNA (siRNA) on HCC cell proliferation and invasion.
  
  
  RESULTS
  The expression of miR-320a was downregulated in 50 HCC tissues and 4 HCC cells. Luciferase assay revealed that c-Myc is a direct target of miR-320a. IHC and Western blot analysis showed that the c-Myc expression was inhibited by miR-320a in HCC tissues and cell lines. Upregulation of miR-320a suppressed the HCC cell proliferation and invasion capacity induced by inhibiting c-Myc, and the results were consistent with the effects of c-Myc siRNA on tumor suppression. These results revealed that miRNA-320a inhibits tumor proliferation and invasion by targeting c-Myc in HCC cells.
  
  
  CONCLUSIONS
  Our results showed that miR-320a functions as a tumor suppressor in HCC. By targeting c-Myc directly, miR-320a inhibits the HCC cell growth. Our studies provide evidence of miR-320a as a potentially target for HCC treatment.
authors.affiliation: School of Medicine, Yunnan University, Kunming, Yunnan.
authors.forename: Fei
authors.initials: F
authors.lastname: Xie
authors.affiliation: School of Medicine, Yunnan University, Kunming, Yunnan.
authors.forename: Yuncang
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Stomatology, Shanghai Tenth People's Hospital, Shanghai.
authors.forename: Luyang
authors.initials: L
authors.lastname: Xie
authors.affiliation: School of Medicine, Yunnan University, Kunming, Yunnan.
authors.forename: Pengzhan
authors.initials: P
authors.lastname: Ran
authors.affiliation: Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, People's Republic of China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Xiang
authors.affiliation: School of Medicine, Yunnan University, Kunming, Yunnan.
authors.forename: Qionglin
authors.initials: Q
authors.lastname: Huang
authors.affiliation: School of Medicine, Yunnan University, Kunming, Yunnan.
authors.forename: Guoxiang
authors.initials: G
authors.lastname: Qi
authors.affiliation: School of Medicine, Yunnan University, Kunming, Yunnan.
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Guo
authors.affiliation: School of Medicine, Yunnan University, Kunming, Yunnan.
authors.forename: Chunjie
authors.initials: C
authors.lastname: Xiao
authors.affiliation: School of Medicine, Yunnan University, Kunming, Yunnan.
authors.forename: Shangyong
authors.initials: S
authors.lastname: Zheng
keywords: c-Myc; hepatocellular carcinoma; miR-320a; tumor suppressors