title: Effect of antisense RNA targeting polo-like kinase 1 on cell cycle and proliferation in A549 cells.
abstract: BACKGROUND
  Expression of polo-like kinase 1 (Plk1) is elevated in lung cancer and has been proposed as having prognostic value and related to resistance to chemotherapy and radiation. In addition, Plk1 has several functions in mitotic progression. In this study, the authors investigated the effect of Plk1 depletion on cell cycle progression and proliferation in A549 cells, a lung cancer cell line.
  
  
  METHODS
  A recombinant plasmid containing antisense RNA targeting Plk1 (pcDNA3-Plk1) was transfected into A549 cells. Reverse transcription-polymerase chain reaction and Western blot were used to examine Plk1 gene expression. Cell proliferation was evaluated by direct cell counting and bromodeoxyuridine (BrdU) labelling. Cell cycle and apoptosis were examined by flow cytometry. Expression of alpha-tubulin was detected by immunofluorescence, and the inhibition rate (IR) by chemotherapeutic agents was determined by 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl-tetrazolium bromide assay.
  
  
  RESULTS
  After transfection into A549 cells, pcDNA3-Plk1 reduced Plk1 mRNA by 46.75% for 24 hours and by 61.84% for 48 hours. Plk1 protein was significantly decreased simultaneously (P < 0.05). Abnormal morphological changes of cells and growth inhibition were observed in pcDNA3-Plk1 transfected groups. The BrdU labelling index was 25.59% 48 hours after transfection, which was significantly lower than that of the control groups (P < 0.05). Forty-eight hours after transfection, there showed absence of microtubule polymerization and spindle abnormalities in staining for alpha-tubulin. A549 cells showed a strong G2/M arrest and apoptosis 72 hours post transfection. IR of vinorelbine in pcDNA3-Plk1 transfected groups was significantly higher than that of the other groups (P < 0.05, respectively).
  
  
  CONCLUSIONS
  Plk1 depletion interferes with spindle formation, induces cell cycle arrest and apoptosis, and consequently inhibits cell proliferation in A549 cells. Moreover, it sensitizes lung cancer cells to chemotherapy.
authors.affiliation: Department of Respiratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zhou
authors.forename: Ming
authors.initials: M
authors.lastname: Bai
authors.forename: Yuan
authors.initials: Y
authors.lastname: Su
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001973:Bromodeoxyuridine / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000473:pathology; D011494:Protein Kinases / Q000235:genetics / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D016372:RNA, Antisense / Q000494:pharmacology*; D014162:Transfection; D014747:Vinblastine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000077235:Vinorelbine; D020687:cdc25 Phosphatases / Q000378:metabolism; D000097869:Polo-Like Kinase 1
chemical_list: D001973:Bromodeoxyuridine; D018797:Cell Cycle Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D016372:RNA, Antisense; D014747:Vinblastine; D000077235:Vinorelbine; D020687:cdc25 Phosphatases; D000097869:Polo-Like Kinase 1; C517009:CDC25C protein, human