Molecular Basis for the Induction of an Angiogenesis Inhibitor, Thrombospondin-1, by 5-Fluorouracil

• Published in: Cancer research (Chicago, Ill.) Vol. 68; no. 17; pp. 7035 - 7041
• Main Authors: ZHAO, Hong-Ye, OOYAMA, Akio, FUKUSHIMA, Masakazu, NAKAGAWA, Masayuki, ONO, Mayumi, KUWANO, Michihiko, AKIYAMA, Shin-Ichi, YAMAMOTO, Masatatsu, IKEDA, Ryuji, HARAGUCHI, Misako, TABATA, Sho, FURUKAWA, Tatsuhiko, CHE, Xiao-Fang, SHAOXUAN ZHANG, OKA, Toshinori
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.09.2008
• Subjects: Antimetabolites, Antineoplastic - pharmacology; Antineoplastic agents; Base Sequence; Biological and medical sciences; Cell Line, Tumor; Chromatin Immunoprecipitation; Colonic Neoplasms - metabolism; Colonic Neoplasms - pathology; DNA Primers; Dose-Response Relationship, Drug; Early Growth Response Protein 1 - metabolism; Enzyme Activation; Fluorouracil - pharmacology; Humans; Medical sciences; Microscopy, Confocal; Microscopy, Fluorescence; Neovascularization, Pathologic; p38 Mitogen-Activated Protein Kinases - metabolism; Pharmacology. Drug treatments; Promoter Regions, Genetic; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; Thrombospondin 1 - biosynthesis; Thrombospondin 1 - genetics; Tumors; Antineoplastic agent; Enzyme; Induction; Fluoropyrimidine derivatives; Transferases; Enzyme inhibitor; Thymidylate synthase; Thrombospondin 1; Antimetabolic; Methyltransferases; Pyrimidine derivatives; Antiangiogenic agent; Molecular biology; Fluorouracil
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.CAN-07-6496

5-Fluorouracil (5-FU) is one of the most commonly used anticancer drugs in chemotherapy against various solid tumors. 5-FU dose-dependently increased the expression levels of intrinsic antiangiogenic factor thrombospondin-1 (TSP-1) in human colon carcinoma KM12C cells and human breast cancer MCF7 cells. We investigated the molecular basis for the induction of TSP-1 by 5-FU in KM12C cells. Promoter assays showed that the region with the Egr-1 binding site is critical for the induction of TSP-1 promoter activity by 5-FU. The binding of Egr-1 to the TSP-1 promoter was increased in KM12C cells treated with 5-FU. Immunofluorescence staining revealed that 5-FU significantly increased the level of Egr-1 in the nuclei of KM12C cells. The suppression of Egr-1 expression by small interfering RNA decreased the expression level of TSP-1. Furthermore, 5-FU induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and heat shock protein 27 (HSP27). Blockade of the p38 MAPK pathway by SB203580 remarkably inhibited the phosphorylation of HSP27 induced by 5-FU and decreased the induction of Egr-1 and TSP-1 by 5-FU in KM12C cells. These findings suggest that the p38 MAPK pathway plays a crucial role in the induction of Egr-1 by 5-FU and that induced Egr-1 augments TSP-1 promoter activity, with the subsequent production of TSP-1 mRNA and protein.