title: miR-7 inhibits colorectal cancer cell proliferation and induces apoptosis by targeting XRCC2.
abstract: BACKGROUND
  Analysis using publicly available algorithms predicts that X-ray repair complementing defective repair in Chinese hamster cells 2 (XRCC2), a key component in the homologous recombination repair pathway, is a potential target of micro-ribonucleic acid-7 (miR-7). Some studies have shown that both miR-7 and XRCC2 are associated with cancer development. For this purpose, we searched for the possible relationship between miR-7 and XRCC2 in the development of colorectal cancer (CRC).
  
  
  METHODS
  miR-7 expression was assessed in CRC specimens and cell lines using real-time polymerase chain reaction (PCR). Luciferase reporter assay was used to confirm the target associations. The effect of miR-7 on cell proliferation and apoptosis was confirmed in vitro by the methylthiazol tetrazolium (MTT) assay, colony formation assay, and flow cytometry. Gene and protein expression were examined using real time PCR and western blotting, respectively.
  
  
  RESULTS
  miR-7 was downregulated in CRC specimens and cell lines, and targeted the 3' untranslated region of XRCC2. miR-7 overexpression reduced cyclin D1 expression and increased p21, caspase-3, and BAX expression, which subsequently inhibited CRC cell proliferation and induced CRC cell apoptosis. However, XRCC2 can repress the inhibitory effects of miR-7 on proliferation.
  
  
  CONCLUSIONS
  Our findings suggest that miR-7 plays a protective role by inhibiting proliferation and increasing apoptosis of CRC cells. It may identify new targets for anti-cancer treatment.
authors.affiliation: Gastrointestinal and Pancreatic Surgery Department, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, People's Republic of China.
authors.forename: Kaiwu
authors.initials: K
authors.lastname: Xu
authors.affiliation: Gastrointestinal and Pancreatic Surgery Department, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, People's Republic of China.
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Gastrointestinal and Pancreatic Surgery Department, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, People's Republic of China.
authors.forename: Changjiang
authors.initials: C
authors.lastname: Qin
authors.affiliation: Gastrointestinal and Pancreatic Surgery Department, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, People's Republic of China.
authors.forename: Xinming
authors.initials: X
authors.lastname: Song
keywords: DNA; MiRNA; downregulated; overexpression