title: Alternative splicing of TIA-1 in human colon cancer regulates VEGF isoform expression, angiogenesis, tumour growth and bevacizumab resistance.
abstract: The angiogenic capability of colorectal carcinomas (CRC), and their susceptibility to anti-angiogenic therapy, is determined by expression of vascular endothelial growth factor (VEGF) isoforms. The intracellular protein T-cell Intracellular Antigen (TIA-1) alters post-transcriptional RNA processing and binds VEGF-A mRNA. We therefore tested the hypothesis that TIA-1 could regulate VEGF-A isoform expression in colorectal cancers. TIA-1 and VEGF-A isoform expression was measured in colorectal cancers and cell lines. We discovered that an endogenous splice variant of TIA-1 encoding a truncated protein, short TIA-1 (sTIA-1) was expressed in CRC tissues and invasive K-Ras mutant colon cancer cells and tissues but not in adenoma cell lines. sTIA-1 was more highly expressed in CRC than in normal tissues and increased with tumour stage. Knockdown of sTIA-1 or over-expression of full length TIA-1 (flTIA-1) induced expression of the anti-angiogenic VEGF isoform VEGF-A165b. Whereas flTIA-1 selectively bound VEGF-A165 mRNA and increased translation of VEGF-A165b, sTIA-1 prevented this binding. In nude mice, xenografted colon cancer cells over-expressing flTIA-1 formed smaller, less vascular tumours than those expressing sTIA-1, but flTIA-1 expression inhibited the effect of anti-VEGF antibodies. These results indicate that alternative splicing of an RNA binding protein can regulate isoform specific expression of VEGF providing an added layer of complexity to the angiogenic profile of colorectal cancer and their resistance to anti-angiogenic therapy.
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Maryam A
authors.initials: MA
authors.lastname: Hamdollah Zadeh
authors.affiliation: Centre for Research in Biomedicine, Faculty of Health and Life Sciences, University of the West of England, Bristol BS16 1QY, UK.
authors.forename: Elianna M
authors.initials: EM
authors.lastname: Amin
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Coralie
authors.initials: C
authors.lastname: Hoareau-Aveilla
authors.affiliation: Molecular and Population Genetics, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
authors.forename: Enric
authors.initials: E
authors.lastname: Domingo
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Kirsty E
authors.initials: KE
authors.lastname: Symonds
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Xi
authors.initials: X
authors.lastname: Ye
authors.affiliation: Proteomics Facility, Faculty of Veterinary and Medical Sciences, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Heesom
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Salmon
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Olivia
authors.initials: O
authors.lastname: D'Silva
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Kai B
authors.initials: KB
authors.lastname: Betteridge
authors.affiliation: School of Cellular and Molecular Medicine, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Ann C
authors.initials: AC
authors.lastname: Williams
authors.affiliation: Nuffield Dept Clinical and Laboratory Sciences, University of Oxford, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Kerr
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Andrew H J
authors.initials: AH
authors.lastname: Salmon
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Oltean
authors.affiliation: Molecular and Population Genetics, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
authors.forename: Rachel S
authors.initials: RS
authors.lastname: Midgley
authors.affiliation: Centre for Research in Biomedicine, Faculty of Health and Life Sciences, University of the West of England, Bristol BS16 1QY, UK.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Ladomery
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Harper
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
authors.forename: Alexander H R
authors.initials: AH
authors.lastname: Varey
authors.affiliation: Microvascular Research Laboratories, Veterinary Sciences Building, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK; Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, NG7 2UH, UK. Electronic address: David.Bates@nottingham.ac.uk.
authors.forename: David O
authors.initials: DO
authors.lastname: Bates
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D000068258:Bevacizumab; D003110:Colonic Neoplasms / Q000098:blood supply / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D019008:Drug Resistance, Neoplasm; D015972:Gene Expression Regulation, Neoplastic; D057809:HEK293 Cells; D006367:HeLa Cells; D064593:Heterografts; D006801:Humans; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D039102:Poly(A)-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics; D000074019:T-Cell Intracellular Antigen-1; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D009363:Neoplasm Proteins; D039102:Poly(A)-Binding Proteins; D020033:Protein Isoforms; D000074019:T-Cell Intracellular Antigen-1; C071558:TIA1 protein, human; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab
keywords: Splicing; TIA-1; VEGF; VEGF(165)b