Transendothelial migration of colon carcinoma cells requires expression ofE-selectin by endothelial cells and activation of stress-activated proteinkinase-2 (SAPK2/p38) in the tumor cells

Adhesion and migration of tumor cells on and through the vascular endotheli um are critical steps of the metastatic invasion. We investigated the roles of E-selectin and of stress-activated protein kinase-2 (SAPK2/p38) in modu lating endothelial adhesion and transendothelial migration of HT-29 colon c arcinoma cells. Tumor necrosis factor alpha (TNF alpha) strongly increased the expression of E-selectin in human umbilical vein endothelial cells (HUV EC). This effect was independent of the activation of SAPK2/p38 induced by TNF alpha. Adhesion of HT-29 cells on a monolayer of HUVEC pretreated with TNFa was dependent on E-selectin expression but was independent of SAPK2/p3 8 activity of both HUVEC and tumor cells. The adhesion of HT-29 cells to E- selectin-expressing HUVEC led to the activation of SAPK2/p38 in the tumor c ells as reflected by the increased phosphorylation of the actin-polymerizin g factor HSP27 by mitogen-activated protein kinase 2/3, a direct target of SAPK2/ p38. Moreover, a recombinant E-selectin/Fc chimera quickly increased the activation of SAPK2/p38 in HT-29 cells. Blocking the increased activit y of SAPK2/p38 of HT-29 cells by SB203580 or by expressing a dominant negat ive form of SAPK2/p38 inhibited their transendothelial migration. Similarly , HeLa cells stably expressing a kinase-inactive mutant of SAPK2/p38 showed a decreased capacity to cross a layer of HUVEC. Overall, our results sugge st that the regulation of transendothelial migration of tumor cells involve s two essential steps as follows: adhesion to the endothelium through adhes ion molecules, such as E-selectin, and increased motogenic potential throug h adhesion-mediated activation of the SAPK2/p38 pathway.