Wheat germ lectin induces G2/M arrest in mouse L929 fibroblasts

• Published in: Journal of cellular biochemistry 2004-04, Vol.91 (6), p.1159-1173
• Main Authors: Liu, W.K., Sze, S.C.W., Ho, J.C.K., Liu, B.P.L., Yu, M.C.
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis - drug effects; bcl-2-Associated X Protein; Caspase 3; Caspases - metabolism; CDC2 Protein Kinase; cdc25 Phosphatases - metabolism; Cell Cycle Proteins - metabolism; Cell Line; Cyclin B - metabolism; cyclin kinase inhibitor; Cyclin-Dependent Kinase Inhibitor p21; Cyclins - metabolism; DNA - biosynthesis; Fibroblasts - cytology; Fibroblasts - physiology; G2 Phase - drug effects; G2 Phase - physiology; growth arrest; L929 fibroblast cell line; Lipid Peroxidation - drug effects; Metaphase - drug effects; Mice; Proto-Oncogene Proteins c-bcl-2 - metabolism; Signal Transduction - drug effects; Vacuoles - physiology; Wheat Germ Agglutinins - pharmacology; wheat germ lectin
• ISSN: 0730-2312; 1097-4644
• DOI: 10.1002/jcb.10755

Wheat germ lectin (WGA) is a cytotoxic lectin for many cell lines [Wang et al., 2000], but its underlying mechanism is not clear. In this report, we found that incubation of synchronized mouse L929 fibroblasts with WGA resulted in a dose‐dependent reduction of intracellular incorporation of 3H‐thymidine and MTT (3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5 diphenyl tetrazolium bromide)‐conversion activity (IC50 ≅ 0.4 μM). Fluorescein‐conjugated WGA was demonstrated to transport from the cell surface into the paranuclear region of cultured L929 cells within 30 min, and subsequently evoked lipid peroxidation of plasma membrane and vacuolation in the cytoplasm of these cells. Studies with tritiated thymidine incorporation, immunofluorescence microscopy, immunoblotting analysis and flow cytometry revealed that WGA inhibited cell cycle progression after one replication, resulting in G2/M arrest and alteration of cell cycle regulatory proteins, particularly activation of p21Cip1/WAF1 and suppression of cyclin B and cdc 2. Although there was an increase of cytosolic caspase 3 and bax protein expression, no apoptotic bodies were observed by both fluorescence and transmission electron microscopy. These results suggest that WGA arrested L929 proliferation after one cell cycle in the G2/M phase through activation of the p21Cip1/WAF1 and suppression of Cyclin B–Cdc2. © 2004 Wiley‐Liss, Inc.