POLYAMINES ARE IMPORTANT FOR ATTACHMENT OF IEC-6 CELLS TO EXTRACELLULAR-MATRIX

The inhibition of ornithine decarboxylase, a rate-limiting enzyme of p olyamine biosynthesis, with a-difluoromethylornithine in IEC-6 cells ( small intestinal crypt cell line) reduces cell migration by 70%, inhib its protein crosslinking, and affects the cytoskeletal assembly. The c urrent study examines the effects of intracellular polyamine depletion on attachment of IEC-6 cells to different matrices. Polyamine deficie ncy inhibited cell attachment to plastic, laminin, fibronectin, collag en IV, and Matrigel by different extents. Intracellular putrescine res tored attachment to all matrices. The presence of a specific inhibitor of protein cross-linking also inhibited attachment to laminin in a do se-dependent manner. The inhibition of cell attachment to plastic and Matrigel was correlated with the inhibition of cell migration. Immunof luorescence studies showed that polyamines are essential for the corre ct expression of the integrin subunit alpha(2) but not for the express ion of the alpha(1)-subunit. This study demonstrates that polyamines a re important for cell attachment and expression of the integrin alpha( 2) beta(1), a putative receptor for collagen and laminin. The impairme nt of protein cross-linking and the inhibition of the expression of ce ll surface receptors that bind extracellular matrix (ECM) proteins may be part of the mechanism by which polyamine deficiency retards cell m igration in the small intestine.