HEF1 is a necessary and specific downstream effector of FAK that promotes the migration of glioblastoma cells

Abstract

The highly invasive behavior of glioblastoma cells contributes to the morbidity and mortality associated with these tumors. The integrin-mediated adhesion and migration of glioblastoma cells on brain matrix proteins is enhanced by stimulation with growth factors, including platelet-derived growth factor (PDGF). As focal adhesion kinase (FAK), a nonreceptor cytoplasmic tyrosine kinase, has been shown to promote cell migration in various other cell types, we analysed its role in glioblastoma cell migration. Forced overexpression of FAK in serumstarved glioblastoma cells plated on recombinant (rec)-osteopontin resulted in a twofold enhancement of basal migration and a ninefold enhancement of PDGF-BBstimulated migration. Both expression of mutant FAK(397F) and the downregulation of FAK with small interfering (si) RNA inhibited basal and PDGF-stimulated migration. FAK overexpression and PDGF stimulation was found to increase the phosphorylation of the Crk-associated substrate (CAS) family member human enhancer of filamentation 1 (HEF1), but not p130CAS or Src-interacting protein (Sin)/Efs, although the levels of expression of these proteins was similar. Moreover downregulation of HEF1 with siRNA, but not p130CAS, inhibited basal and PDGF-stimulated migration. The phosphorylated HEF1 colocalized with vinculin and was associated almost exclusively with 0.1% Triton X-100 insoluble material, consistent with its signaling at focal adhesions. FAK overexpression promoted invasion through normal brain homogenate and siHEF1 inhibited this invasion. Results presented here suggest that HEF1 acts as a necessary and specific downstream effector of FAK in the invasive behavior of glioblastoma cells and may be an effective target for treatment of these tumors.

Signaling adaptor protein Crk is indispensable for malignant feature of glioblastoma cell line KMG4

“…Considering that Crk localized in focal adhesion forming by integrin 1b stimulation [32] and integrin 1 regulates PI-3 kinase though p130 Cas [33], Crk may function downstream of laminin involving in cell survival of glioblastoma. Furthermore, implication of Crk in glioblastoma cell growth is also supported by the data that HEF1 which is Cas family docking protein for Crk, was reported to be essential for tumor growth [34].…”

Integrin signalling adaptors: not only figurants in the cancer story

“…Also in glioblastoma cells, NEDD9 is pro-migratory upon platelet-derived growth factor (PDGF)-stimulation 67 . Opposite effects have been reported in a recent siRNA screen of human mammary epithelial cells.…”

HEF1-Aurora A Interactions: Points of Dialog between the Cell Cycle and Cell Attachment Signaling Networks

“…71,72,96,97 It is most abundant in vivo in tissues with polarized cell populations, including epithelial cells, neuronal and glial cells, and lymphoid cells, and its signaling action may be particularly important in these cell lineages. 97,98 p130Cas is abundant at all phases of cell cycle. In contrast, HEF1 is very low in G 0 /G 1 phase cells, with abundance peaking in G 2 and M phase.…”