title: Suppression of human lung cancer cell proliferation and metastasis in vitro by the transducer of ErbB-2.1 (TOB1).
abstract: OBJECTIVE
  To investigate the effects of the transducer of ErbB-2.1 (TOB1) on the proliferation, migration and invasion of human lung cancer cells in vitro.
  
  
  METHODS
  Human lung cancer cell lines (95-D, A549, NCI-H1299, NCI-H1975, NCI-H661, NCI-H446, NCI-H1395, and Calu-3) and the normal human bronchial epithelial (HBE) cell line were tested. The expression levels of TOB1 in the cells were determined with Western blot and RT-PCR analyses. TOB1-overexpressing cell line 95-D/TOB1 was constructed using lipofectamine-induced TOB1 recombinant plasmid transfection and selective G418 cell culture. The A549 cells were transcend-transfected with TOB1-siRNA. MTT assay, flow cytometry and Western blot analysis were used to examine the effects of TOB1 on cancer cell proliferation and wound healing. Transwell invasive assay was performed to evaluate the effects of TOB1 on cancer cell migration and invasion. The activity of MMP2 and MMP9 was measured using gelatin zymography assay.
  
  
  RESULTS
  The expression levels of TOB1 in the 8 human lung cancer cell lines were significantly lower than that in HBE cells. TOB1 overexpression inhibited the proliferation of 95-D cells, whereas TOB1 knockdown with TOB1-siRNA promoted the growth of A549 cells. Decreased cell migration and invasion were detected in 95-D/TOB1 cells, and the suppression of TOB1 enhanced the metastasis in A549 cells. TOB1 overexpression not only increased the expression of the phosphatase and tensin homolog (PTEN), an important tumor suppressor, but also regulated the downstream effectors in the PI3K/PTEN signaling pathway, including Akt, ERK1/2, etc. In contrast, decreased expression of TOB1 oppositely regulated the expression of these factors. TOB1 also regulates the gelatinase activity of MMP2 and MMP9 in lung cancer cells.
  
  
  CONCLUSIONS
  The results demonstrate that the PI3K/PTEN pathway, which is essential for carcinogenesis, angiogenesis, and metastasis, may be one of the possible signaling pathways for regulation of proliferation and metastasis of human lung cancer cells by TOB1 in vitro.
authors.affiliation: Key Laboratory of Radiation Biology, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Jiao
authors.forename: Ke-kang
authors.initials: KK
authors.lastname: Sun
authors.forename: Lin
authors.initials: L
authors.lastname: Zhao
authors.forename: Jia-ying
authors.initials: JY
authors.lastname: Xu
authors.forename: Li-li
authors.initials: LL
authors.lastname: Wang
authors.forename: Sai-jun
authors.initials: SJ
authors.lastname: Fan
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051059:PTEN Phosphohydrolase / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C098669:TOB1 protein, human; D025521:Tumor Suppressor Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human