title: [Effects of RNA interference of COX-2 gene expression on malignant proliferation of A549 cells in vitro].
abstract: OBJECTIVE
  To investigate the inhibition of COX-2 gene expression and its effects on malignant proliferation of human lung adenocarcinoma A549 cells after interfering at different target sites in vitro.
  
  
  METHODS
  The 3rd, 7th and 10th exon of COX-2 were selected as the targets and three COX-2 siRNA expression vectors with human U6 promoter were constructed. Three siRNA expression vectors and two vacant vectors were transfected into A549 cells expressing COX-2 with lipofectamine, respectively. The transfected cell strains were constructed and the change of COX-2 expression levels was examined by Western blot and RT-PCR. The effects on the proliferation of A549 cells after interfering at different target sites were studied by cell growth curve and colony formation assay in vitro.
  
  
  RESULTS
  The three siRNAs and U6 promoter were validated by PCR, restriction endonuclease digestion, DNA sequencing and BLAST alignment, and cloned into the pEGFP vector. The cell strains transfected were named as A549-3, A549-7, A549-10, A549-p and A549-pU6, respectively. A549-p cells showed expression of GFP and A549-3, A549-7, A549-10, A549-p and A549-pU6 cells did not show at 24, 48 and 72 hours after transfection. The results of RT-PCR and Western blot showed an inhibition of COX-2 expression after interfering at three target sites (3rd, 7th and 10th exons). In contrast to A549 cells, the levels of COX-2 mRNA of A549-3, A549-7 and A549-10 cells were reduced by 10.6%, 33.4% and 61.2%, respectively. The levels of COX-2 protein of A549-3, A549-7 and A549-10 cells were reduced by 26.7%, 44.7% and 56.2%, respectively. The results of cell growth curve and colony formation assay showed a slowing down of the growth of A549-10 cells and reduction of their colony formation rate. The other two targets had no apparent effect on the growth of A549 cells.
  
  
  CONCLUSIONS
  There is a significant inhibiting effect of RNA interference on the malignant proliferation of A549 cells in vitro, and the most striking effect can be seen when the 10th exon of COX-2 is taken as the interference target.
authors.affiliation: Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, China.
authors.forename: Wei-Ying
authors.initials: WY
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Bai-Tang
authors.initials: BT
authors.lastname: Lai
authors.forename: Xue-Hui
authors.initials: XH
authors.lastname: Yang
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Zhang
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D005091:Exons; D005822:Genetic Vectors; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics*; D014162:Transfection
chemical_list: D012333:RNA, Messenger; D034741:RNA, Small Interfering; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human