Analysis of anticancer and cytotoxic mechanism of an Aralia elata-derived antitumor protein, aralin.

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17590098
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Drug development chemistry
• Research Institution: Tokyo University of Science
• Principal Investigator: TASHIRO Fumio Tokyo University of Science, Faculty of Department of Biological Science and Technology Faculty of Industrial Science and Technology, 基礎工学部, 教授 (70089332)
• Co-Investigator(Kenkyū-buntansha): KAWASAKI Yasushi Tokyo University of Science, Faculty of Industrial Science and Technology, 基礎工学部, 助手 (60385549) ; TOMATSU Makoto Akita Research Institute of Food and Brewing, 総合食品研究所, 主任研究員 (40399770)
• Project Period (FY): 2005 – 2006
• Keywords: Aralia elata / anticancer / lectin / RNA N-glycosidase / ribosome inactivating protein / callus

Research Abstract

We found that aralin, a novel cytotoxic protein from Aralia elate, selectively induces apoptosis in transformed cells. Aralin is a lectin specific for galactose (Gal) and possesses RNA N-glycosidase activity. In this study, to elucidate the anticancer and cytotoxic mechanism evoked by aralin, we analyzed the tumorigencity when aralin administrate into the HeLa cells transplanted nude mice and intracellular localization of aralin using Tetramethylrhodamine (TAMRA)-conjugated aralin and its recognizing protein using far-Western blot analysis. The homogenate of Aralia elate including 2 μg of aralin were administer orally in the HeLa cells injected into nude mice for 3 weeks of 5 days on the week. The tumors formed by HeLa cells were remarkably decreased on the aralia elate administering group. TAMRA-aralin bound to cell membrane and then migrated into the cytosol, following to transport into endoplasmic reticulum in a time-dependent manner. The binding of TAMRA-aralin to cell membrane was significantly inhibited by the addition of Gal, which also repressed the cytotoxic effect of aralin. To analyze the aralin interacting proteins, we performed a far-Western blotting using aralin as a probe and anti-aralin antibody for the membrane fractions from HeLa cells, normal human lung fibroblast WI-38 cells and its SV40-transformed VA-13 cells. The results showed that 30 and 57 kDa proteins of VA-13 and HeLa cells were bound to aralin. These interactions were not influenced by ricin, whereas almost inhibited in presence of Gal. These data suggest that aralin is antitumor protein and incorporated into cells through its Gal-containing cell surface receptor, and induces cell death by the inhibition of protein synthesis.