title: Raf/ERK/Nrf2 signaling pathway and MMP-7 expression involvement in the trigonelline-mediated inhibition of hepatocarcinoma cell migration.
abstract: BACKGROUND
  Trigonelline occurs in many dietary food plants and has been found to have anti-carcinogenic activity. Trigonelline is also found in coffee which is one of the most widely consumed beverages. Many epidemiological studies have reported that coffee consumption has an inverse relationship with the risk of cirrhosis or hepatocellular carcinoma. It would be interesting to investigate whether trigonelline is an ideal chemoprevent agent to prevent cancer progression.
  
  
  METHODS
  The protein expression was performed by western blotting. The trigonelline content in snow pea (Pisum sativum) was analyzed by high-performance liquid chromatography (HPLC). The migratory activity of human hepatocarcinoma cells (Hep3B) was assessed by using a wound migration assay. The percentage of each phase in the cell cycle was analyzed on a FACScan flow cytometer. Gene expression was detected by real-time reverse transcriptase-polymerase chain reaction techniques. Native gel analysis was performed to analyze the activity of superoxide dismutase (SOD), catalase and glutathione peroxidase.
  
  
  RESULTS
  According to the data of HPLC analysis, P. sativum, which is a popular vegetable, has relatively high content of trigonelline. Our findings suggest that trigonelline is an efficient compound for inhibiting Hep3B cell migration. Trigonelline inhibited the migration of hepatoma cells at concentrations of 75-100 µM without affecting proliferation. Raf/ERK/Nrf2 protein levels and further downstream antioxidative enzymes activity, such as SOD, catalase, and glutathione peroxidase, significantly decreased after treatment with 100 µM of trigonelline for 24 h. The migration inhibition of trigonelline is also related to its ability to regulate the matrix metalloproteinases 7 (MMP-7) gene expression.
  
  
  CONCLUSIONS
  In this study, protein kinase Cα (PKCα) and Raf/ERK/Nrf2 signaling pathway and MMP-7 gene expression were involved in the trigonelline-mediated migration inhibition of Hep3B cells. We also demonstrated that trigonelline inhibits Hep3B cell migration through downregulation of nuclear factor E2-related factor 2-dependent antioxidant enzymes activity. This study analyzed the trigonelline content in a popular vegetable, snow pea, as a representative proof to prove that trigonelline is often found in the daily intake of food. Our finding suggested that trigonelline should be a useful chemopreventive agent derived from the daily intake of food to prevent cancer progression.
authors.affiliation: School of Pharmacy, China Medical University, Taichung, Taiwan.
authors.forename: Jung Chun
authors.initials: JC
authors.lastname: Liao
authors.affiliation: Department of Oral Hygiene, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Kun Tsung
authors.initials: KT
authors.lastname: Lee
authors.affiliation: School of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, China Medical University, Taichung, Taiwan.
authors.forename: Bang Jau
authors.initials: BJ
authors.lastname: You
authors.affiliation: Department of Cosmeceutics and Graduate Institute of Cosmeceutics, China Medical University, Taichung, Taiwan.
authors.forename: Chia Lin
authors.initials: CL
authors.lastname: Lee
authors.affiliation: School of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, China Medical University, Taichung, Taiwan.
authors.forename: Wen Te
authors.initials: WT
authors.lastname: Chang
authors.affiliation: School of Pharmacy, China Medical University, Taichung, Taiwan.
authors.forename: Yang Chang
authors.initials: YC
authors.lastname: Wu
authors.affiliation: School of Pharmacy, China Medical University, Taichung, Taiwan.|Pharmacy Department, Tainan Municipal An-Nan Hospital-China Medical University, Tainan, Taiwan; hong@mail.cmu.edu.tw.
authors.forename: Hong-Zin
authors.initials: HZ
authors.lastname: Lee
keywords: MMP-7; Pisum sativum; Raf/ERK/Nrf2 signaling pathway; chemotherapeutic agent; hepatocarcinoma Hep3B cells; migration; trigonelline