클로렐라 열수추출물이 IEC-6 세포의 세포증식에 미치는 영향

Abstract

Chlorella is a unicellular microalgae that is ubiquitous in freshwater environments. It contains highly nutritious substances such as protein, carbohydrates, vitamins, minerals, fatty acids, dietary fibers and nucleic acids and exerts various biological effects. Hot water extract of chlorella is a biological response modifier (BRM) which modulates immune responses against tumors, bacteria and viruses. But the effect of hot water extract of Chlorella vulgaris on normal cell proliferation has not been studied. In this study, the hot water extract of Chlorella vulgaris (CVE) was gained which had a proliferative effect, and examined signal transduction pathways focusing on insulin-like growth factor-I receptor (IGF-IR), focal adhesion kinase (FAK)/Src signaling and Wnt pathways. The IGF system plays essential role in the regulation of cell growth, proliferation and survival. FAK is a protein tyrosine kinase that appears to have many functions in cells, linking integrin signaling to down stream targets, acting as part of a survival signal pathway and having connection with cell motility. CVE induced the increased expression of IGF-IR and the activation of FAK and Src. IGF-IR and FAK induce activation of multiple intracellular signal transduction cascades, including the phosphatidyl-inositol 3-kinase (PI3K)-Akt pathway and the mitogen-activated protein kinase (MAPK) pathway. In this study, CVE induced the activation of ERK but not the activation of JNK and p38. And it induced the increased expression of p85 and the activation of Akt. At least three different Wnt pathways are currently recognized: the canonical Wnt pathway, which is mediated via β-catenin and T cell-specific transcription factor/lymphoid enhancer-binding factor (TCF/LEF) factors; the planar cell polarity (PCP) pathway; and the Wnt-Ca2+ pathway. The canonical Wnt pathway is essential for cell proliferation and development. As a result of the experiments, CVE induced the increased expression of nuclear β-catenin and cyclin D1. Tyr-397 site of FAK can mediate interactions with SH2 domains of a number of other signaling proteins including PI3K, PLC-γ, Shc, Grb7, Src and Nck2. Because we confirmed that CVE has proliferative effect on IEC-6 cells via FAK activation, we examined whether FAK inhibitor can effect on canonical Wnt pathway. As a result, the treatment of FAK inhibitor induced the decreased expression of nuclear β-catenin, cyclin D1, c-myc and increased expression of cytosol β-catenin. These results indicate that CVE stimulates cell proliferation via MAPK pathway, PI3K/Akt pathway and canonical Wnt signaling pathway. And activation of FAK influences canonical Wnt signaling pathway: translocation of cytosolic β-catenin to nucleus. Gastrointestinal damage associated with the use of non steroidal anti-inflammatory drugs (NSAID) and chemotherapy. Therefore CVE has a potential application as functional foods for protecting gastro-intestinal tract.