title: Coordinated expression of REG4 and aldehyde dehydrogenase 1 regulating tumourigenic capacity of diffuse-type gastric carcinoma-initiating cells is inhibited by TGF-β.
abstract: Aldehyde dehydrogenase 1 (ALDH1) has been shown to serve as a marker for cancer-initiating cells (CICs), but little is known about the regulation of the CIC functions of ALDH1+ cancer cells. We isolated ALDH1+ cells from human diffuse-type gastric carcinoma cells and characterized these cells using an Aldefluor assay. ALDH1+ cells constituted 5-8% of the human diffuse-type gastric carcinoma cells, OCUM-2MLN and HSC-39; were more tumourigenic than ALDH1- cells; and were able to self-renew and generate heterogeneous cell populations. Using gene expression microarray analyses, we identified REG4 (regenerating islet-derived family, member 4) as one of the genes up-regulated in ALDH1+ cells, and thus as a novel marker for ALDH1+ tumour cells. Induced expression of REG4 enhanced the colony-forming ability of OCUM-2MLN cells, while knockdown of REG4 inhibited the tumourigenic potential of ALDH1+ cells. We further found that TGF-β signalling reduces the expression of ALDH1 and REG4, and the size of the ALDH1+ cell population. In human diffuse-type gastric carcinoma tissues, the expression of ALDH1 and REG4 correlated with each other, as assessed by immunohistochemistry, and ALDH1 expression correlated inversely with Smad3 phosphorylation as a measure of TGF-β signalling. These findings illustrate that, in diffuse-type gastric carcinoma, REG4 is up-regulated in ALDH1+ CICs, and that the increased tumourigenic ability of ALDH1+ cells depends on REG4. Moreover, TGF-β down-regulates ALDH1 and REG4 expression, which correlates with a reduction in CIC population size and tumourigenicity. Targeting REG4 in ALDH1+ CICs may provide a novel strategy in the treatment of diffuse-type gastric carcinoma.
authors.affiliation: Department of Molecular Pathology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Katsuno
authors.forename: Shogo
authors.initials: S
authors.lastname: Ehata
authors.forename: Masakazu
authors.initials: M
authors.lastname: Yashiro
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Yanagihara
authors.forename: Kosei
authors.initials: K
authors.lastname: Hirakawa
authors.forename: Kohei
authors.initials: K
authors.lastname: Miyazono
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000503:physiopathology; D000080924:Aldehyde Dehydrogenase 1 Family; D000818:Animals; D014408:Biomarkers, Tumor / Q000502:physiology; D018279:Carcinoma, Signet Ring Cell / Q000473:pathology / Q000503:physiopathology; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000502:physiology*; D037181:Lectins, C-Type / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000473:pathology / Q000502:physiology*; D000073718:Pancreatitis-Associated Proteins; D050697:Retinal Dehydrogenase / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D013274:Stomach Neoplasms / Q000473:pathology / Q000503:physiopathology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology* / Q000502:physiology; D014183:Transplantation, Heterologous; D015854:Up-Regulation / Q000502:physiology
chemical_list: D014408:Biomarkers, Tumor; D007527:Isoenzymes; D037181:Lectins, C-Type; D000073718:Pancreatitis-Associated Proteins; C428528:REG4 protein, human; D016212:Transforming Growth Factor beta; D000080924:Aldehyde Dehydrogenase 1 Family; C510223:ALDH1A1 protein, human; C515028:ALDH1A1 protein, mouse; D050697:Retinal Dehydrogenase