title: Branched-chain amino acid deficiency stabilizes insulin-induced vascular endothelial growth factor mRNA in hepatocellular carcinoma cells.
abstract: Abnormal sugar metabolism is closely related to chronic liver diseases, including hepatocellular carcinoma (HCC). We previously reported that fasting hyperinsulinemia is a poor prognostic factor for HCC patients. A recent large-scale study has shown that long-term administration of branched chain amino acids (BCAA) reduces the risk of HCC development in obese cirrhotic patients who have been diagnosed with diabetes mellitus, although the mechanism by which it does so is unclear. In this study, we analyzed the expression of vascular endothelial growth factor (VEGF) in HepG2 cells under high-insulin culture conditions, and examined the effect of BCAA on VEGF expression. VEGF secretion was significantly increased by 200 nM of insulin under BCAA deficient conditions, but it was repressed by the addition of BCAA. BCAA activated the mTOR pathway and increase HIF-1α expression under high-insulin culture conditions, however quantitative PCR analysis showed that insulin-induced expression of VEGF mRNAs (VEGF121 and VEGF165) decreased 2 h after the addition of BCAA. The half-lives of both VEGF121 and 165 mRNAs were shortened in the presence of BCAA compared to the absence of BCAA. Therefore it is thought that BCAA regulate VEGF expression mainly at the post-transcriptional level. We also examined which of the Valine, Leucine, and Isoleucine components of BCAA were essential for VEGF mRNA degradation. All three BCAA components were required for acceleration of insulin-induced VEGF mRNA degradation. These results suggest that administration of BCAA may downregulate VEGF expression in patients who have hyperinsulinemia and are in the process of developing HCC.
authors.affiliation: Department of Gastroenterology and Hepatology, Nagasaki University, Sakamoto 1-7-1, Nagasaki 852-8501, Japan. miuma1002@gmail.com
authors.forename: Satoshi
authors.initials: S
authors.lastname: Miuma
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Ichikawa
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Arima
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Takeshita
authors.forename: Toru
authors.initials: T
authors.lastname: Muraoka
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Matsuzaki
authors.forename: Masashi
authors.initials: M
authors.lastname: Ootani
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Shibata
authors.forename: Motohisa
authors.initials: M
authors.lastname: Akiyama
authors.forename: Eisuke
authors.initials: E
authors.lastname: Ozawa
authors.forename: Hisamitsu
authors.initials: H
authors.lastname: Miyaaki
authors.forename: Naota
authors.initials: N
authors.lastname: Taura
authors.forename: Fuminao
authors.initials: F
authors.lastname: Takeshima
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakao
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology*; D003470:Culture Media / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006207:Half-Life; D056945:Hep G2 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism
chemical_list: D000597:Amino Acids, Branched-Chain; D003470:Culture Media; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007328:Insulin; D012333:RNA, Messenger; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases