title: Differentiation-inducing factor-1 (DIF-1) inhibits STAT3 activity involved in gastric cancer cell proliferation via MEK-ERK-dependent pathway.
abstract: Differentiation-inducing factor-1 (DIF-1) is a chlorinated hexaphenone isolated from Dictyostelium. DIF-1 exhibits antitumor activity in several types of mammalian tumor cells, although the underlying mechanisms remain unknown. On the other hand, recent studies indicate that constitutively activated STAT3 acts as an oncogene and could be a target for antitumor drug. In the present study, we examined the effects of DIF-1 on proliferation of gastric cancer cell lines as well as on its signal transduction pathways, focusing mainly on STAT proteins. DIF-1 inhibited proliferation of gastric cancer cells. Western blot analysis and electrophoretic mobility shift assay showed that DIF-1 inhibited STAT3 activity in an MEK-ERK-dependent manner in gastric cancer cell lines, AGS and MKN28. Moreover, blockade of STAT3 activity by ectopic expression of dominant-negative STAT3 or the Janus kinase inhibitor, tyrphostin AG490, inhibited cell growth of AGS cells. These results suggest that STAT3 activity plays an important role for cell growth in AGS cells, and raises the possibility that inhibition of STAT3 activity is one of the mechanisms responsible for the antitumor effect of DIF-1 in these cells.
authors.affiliation: Division of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kanai
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Konda
authors.forename: Toshio
authors.initials: T
authors.lastname: Nakajima
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Izumi
authors.forename: Naoki
authors.initials: N
authors.lastname: Kanda
authors.forename: Apichart
authors.initials: A
authors.lastname: Nanakin
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Kubohara
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Chiba
mesh_terms: D001483:Base Sequence; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins / Q000502:physiology*; D002455:Cell Division / Q000502:physiology*; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D015801:Helminth Proteins / Q000502:physiology*; D006588:Hexanones; D006801:Humans; D006843:Hydrocarbons, Chlorinated; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D050796:STAT3 Transcription Factor; D012694:Serine / Q000378:metabolism; D013274:Stomach Neoplasms / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D015534:Trans-Activators / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D015801:Helminth Proteins; D006588:Hexanones; D006843:Hydrocarbons, Chlorinated; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D050796:STAT3 Transcription Factor; D012694:Serine; D015534:Trans-Activators; C490570:Differentiation-inducing factor-1, Dictyostelium; C494086:STAT3 protein, human