RAFTK/Pyk2 tyrosine kinase mediates the association of p190 RhoGAP with RasGAP and is involved in breast cancer cell invasion

Abstract

Focal adhesions and actin cytoskeleton are involved in cell growth, shape and movement and in tumor invasion. Mitogen-induced changes in actin cytoskeleton are accompanied by changes in the tyrosine phosphorylation of several focal adhesion proteins. In this study, we have investigated the role of RAFTK, a cytoplasmic tyrosine kinase related to focal adhesion kinase (FAK), in heregulin-mediated signal transduction in breast cancer cells. Stimulation of T47D cells with heregulin (HRG) induced the tyrosine phosphorylation of RAFTK and the formation of a multiprotein complex. Analyses of the members of the HRG-stimulated complex revealed that RAFTK is associated with p190 RhoGAP (p190), RasGAP and ErbB-2, and plays an essential role in mediating the tyrosine phosphorylation of p190 by Src. Mutation of the Src binding site within RAFTK (402) abolished the phosphorylation of p190. In addition, upon HRG stimulation of T47D cells, association of ErbB-2 with RAFTK was observed and found to be indirect and mediated by Src. Expression of wild-type RAFTK (WT) signi®cantly increased MDA-MB-435 and MCF-7 breast cancer cell invasion, while expression of the kinasemutated RAFTK-R457 (KM) or the Src binding site mutant RAFTK (402) did not a ect this cell invasion. Furthermore, HRG leads to the activation of MAP kinase which is mediated by RAFTK. These ®ndings indicate that RAFTK serves as a mediator and an integration point between the GAP proteins and HRG-mediated signaling in breast cancer cells, and implicate RAFTK involvement in the MAP kinase pathway and in breast cancer cell invasion.

ErbB-2 via PYK2 upregulates the adhesive ability of androgen receptor-positive human prostate cancer cells

“…We propose that in androgenindependent, AR-positive PCa cells, ErbB-2 protein is constitutively activated and/or elevated as seen in clinical samples due, in part, to the loss or null of cPAcP expression (Signoretti et al, 2000;Veeramani et al, 2005). In those advanced PCa cells, signal pathways initiated by highly activated ErbB-2 lead to a sustained activation of PYK2 and PYK2-mediated functions, which differs from the transient effect activated by ErbB ligands (Zrihan-Licht et al, 2000;van der Horst et al, 2005;Park et al, 2006). Further investigation for the detailed molecular mechanism of ErbB-2 activation is required.…”

“…Since both high passages of LNCaP C-81 and MDA PCa2b cells had higher levels of ErbB-2/PYK2 functional complexes than corresponding low passage cells, it suggested that the association of ErbB-2 with PYK2 in the same complex is critical for PYK2 activation and its regulation of cell adhesion. Although c-Src may serve as a mediator for ErbB-2/PYK2 interaction in 293T cells (Zrihan-Licht et al, 2000), inhibition of c-Src in C-81 cells has no effect on PYK2 activity and the initial adhesion (Supplementary Figure 3B). Further, the K457A-PYK2 mutant can still activate c-Src, while it inhibits ErbB-2-promoted adhesion ( Figure 6, Supplementary Figure 1B).…”

“…PYK2 is involved in a variety of cellular activities, for example, in response to integrin-ECM interaction, GPCR activation, stress signals, cytokine stimulation and intracellular calcium elevation (Dikic et al, 1996(Dikic et al, , 1998. PYK2 is also involved in regulating the migration and invasion of human glioma as well as breast cancer cells (Zrihan-Licht et al, 2000;Lipinski et al, 2005). In PCa cells, PYK2 is involved in regulating the activity of androgen receptor (AR) (Wang et al, 2002).…”

Chemokines: attractive mediators of the immune response

“…FAK is also important in integrin-mediated cell cycle progression through the mitogen activating protein (MAP) kinase pathway [74,75]. Additionally, FAK and Pyk2 activation are implicated in the growth and metastasis of transformed cells [76][77][78]. Together, these data imply that FAK is an important intersection point for cell motility and growth transformation.…”

Up-regulation of ras-GAP genes is reversed by a MEK inhibitor and doxorubicin in v-Ki-ras-transformed NIH/3T3 fibroblasts

“…SH domains of p120-GAP function as effectors by associating with several tyrosine-phosphorylated proteins [5], which induce Ras-dependent gene expression [6] and repress adhesion [7]. In addition, p120-GAP is involved in Ras transformation [8,9], cell survival [10,11,12] tumor cell invasion [13], and v-Src-induced cytoskeletal disruption [14]. Based on these findings, p120-GAP proteins show promise as a target for anticancer approaches [11].…”