Mechanisms of lectin (phytohemagglutinin)-induced growth in small intestinal epithelial cells

Background/Aims: The lectin phytohemagglutinin is a mitogen for intestinal epithelia[ cells in vivo. The mechanisms of action are unknown and were therefore analyzed in vitro. Methods: Human (Intestine-407) and rat (IEC-6; IEC-18) intestinal epithelial cell lines were stimulated with phytohemagglutinin. Proliferation was assayed by H-3-thymidine incorporation, activation of mitogen-activated protein kinase (MAPK) by Western blotting, and induction of c-fos mRNA expression by semi-quantitative polymerase chain reaction. Control experiments were performed with phenyl-N-acetyl-alpha-D-galactosaminide or the tyrosine kinase inhibitor tyrphostin A25. Results: Phytohemagglutinin (0.1 mug/ml) significantly stimulated proliferation in all three cell lines after 48-72 h. MAPK activation was detected after 15-30 min, and an induction of c-fos mRNA expression after 1530 min of stimulation. Mitogenic effects were blocked by preincubation with phenyl-N-acetyl-a-D-galactosaminide or tyrphostin A25. Conclusion: Phytohemagglutinin stimulated proliferation, MAPK activation and induction of c-fos mRNA expression. The lectin may contribute to intestinal mucosal growth and regeneration thereby preventing gut atrophy. Copyright (C) 2001 S. Karger AG, Basel.