title: EGF rapidly translocates tight junction proteins from the cytoplasm to the cell-cell contact via protein kinase C activation in TMK-1 gastric cancer cells.
abstract: Tight junctions are commonly disrupted in cancer cells, including gastric cancer. Various growth factors have been reported to affect the localization of tight junction-associated proteins such as ZO-1 and occludin. We investigated the effect of epidermal growth factor (EGF), a growth factor that is often overexpressed in gastric cancer, and fetal bovine serum (FBS) on the localization of ZO-1 and occludin in a gastric cancer cell line. In the poorly differentiated gastric cancer cell line TMK-1, immunohistochemistry demonstrated that ZO-1 and occludin were predominantly localized to the cytoplasm, although there was some weak expression at the cell-cell contact. When the medium was replaced with fresh medium containing 10% FBS, ZO-1 and occludin were rapidly translocated from the cytosol to the cell-cell contact. A similar effect was seen in EGF exposure. These effects induced by FBS or EGF were attenuated in the presence of protein kinase C (PKC) inhibitors calphostin C and bisindolylmaleimide I, but not another PKC inhibitor Gö6976, PD98059 (MAPK inhibitor), LY294002 (PI3 kinase inhibitor) or KT5720 (protein kinase A inhibitor). These results suggest that serum-derived factors, including EGF, can rapidly alter the localization of ZO-1 and occludin via a protein kinase C signaling pathway in TMK-1 gastric cancer cells.
authors.affiliation: First Department of Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu 431-3192, Japan. ykenichi@hama-med.ac.jp
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Yoshida
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kanaoka
authors.forename: Tetsunari
authors.initials: T
authors.lastname: Takai
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Uezato
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Miura
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kajimura
authors.forename: Akira
authors.initials: A
authors.lastname: Hishida
mesh_terms: D000818:Animals; D002417:Cattle; D002450:Cell Communication / Q000502:physiology; D045744:Cell Line, Tumor; D003470:Culture Media; D003593:Cytoplasm / Q000201:enzymology / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000378:metabolism*; D062793:Occludin; D010750:Phosphoproteins / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000201:enzymology*; D019108:Tight Junctions / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
chemical_list: D003470:Culture Media; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; D004815:Epidermal Growth Factor; D011493:Protein Kinase C