title: Inhibitor of growth 4 suppresses colorectal cancer growth and invasion by inducing G1 arrest, inhibiting tumor angiogenesis and reversing epithelial-mesenchymal transition.
abstract: Previous studies have found that inhibitor of growth 4 (ING4), a tumor suppressor, is reduced in human colorectal cancer (CRC), and is inversely correlated with clinical Dukes' stage, histological grade, lymph node metastasis and microvessel density (MVD). However, its underlying mechanism remains undetermined. In the present study, we analyzed ING4 expression in a panel of human CRC cells using low (LS174T and SW480) and high (LoVo and SW620) metastatic cell lines. We demonstrated that both the low and high metastatic CRC cells exhibited a lower level of ING4 compared to the level in normal human colorectal mucous epithelial FHC cells. Furthermore, ING4 expression in high metastatic CRC cells was less than that in low metastatic CRC cells. We then generated a lentivirus construct expressing ING4 and green fluorescent protein (GFP), established a ING4-stably transgenic LoVo CRC cell line, and investigated the effect of lentiviral-mediated ING4 expression on high metastatic LoVo CRC cells. Gain-of-function studies revealed that ING4 significantly inhibited LoVo CRC cell growth and invasion in vitro and induced cell cycle G1 phase arrest. Moreover, ING4 obviously suppressed LoVo CRC subcutaneously xenografted tumor growth and reduced tumor MVD in vivo in athymic BALB/c nude mice. Mechanistically, ING4 markedly upregulated P21 and E-cadherin but downregulated cyclin E, interleukin (IL)-6, IL-8, vascular endothelial growth factor (VEGF), Snail1, N-cadherin and vimentin in the LoVo CRC cells. Our data provide compelling evidence that i) ING4 suppresses CRC growth possibly via induction of G1 phase arrest through upregulation of P21 cyclin-dependent kinase (CDK) inhibitor and downregulation of cyclin E as well as inhibition of tumor angiogenesis through reduction of IL-6, IL-8 and VEGF proangiogenic factors; ii) ING4 inhibits CRC invasion and metastasis probably via a switch from mesenchymal marker N-cadherin to epithelial marker E-cadherin through downregulation of Snail1 epithelial-mesenchymal transition (EMT)-inducing transcription factor (EMT-TF).
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Qu
authors.affiliation: Department of Oncology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China.
authors.forename: Hong
authors.initials: H
authors.lastname: Yin
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China.
authors.forename: Su
authors.initials: S
authors.lastname: Yan
authors.affiliation: Department of Oncology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China.
authors.forename: Min
authors.initials: M
authors.lastname: Tao
authors.affiliation: Department of Oncology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China.
authors.forename: Weichang
authors.initials: W
authors.lastname: Chen
mesh_terms: D000818:Animals; D015820:Cadherins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000502:physiology*; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D019927:Cyclin E / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D015536:Down-Regulation; D058750:Epithelial-Mesenchymal Transition; D059585:G1 Phase Cell Cycle Checkpoints; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D057809:HEK293 Cells; D018398:Homeodomain Proteins / Q000502:physiology*; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000378:metabolism*; D000071250:Snail Family Transcription Factors / Q000235:genetics / Q000378:metabolism; D047368:Tumor Burden; D025521:Tumor Suppressor Proteins / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: C493956:CDKN1A protein, human; C508606:CXCL8 protein, human; D015820:Cadherins; D018797:Cell Cycle Proteins; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018398:Homeodomain Proteins; C508600:IL6 protein, human; C483230:ING4 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; C000604407:SNAI1 protein, human; D000071250:Snail Family Transcription Factors; D025521:Tumor Suppressor Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A