Requirement of PEA3 for Transcriptional Activation of FAK Gene in Tumor Metastasis

Shufeng Li,Zi-Chun Hua,Dapeng Zhang,Xiaofeng Huang,Renxiang Tan,Qilai Huang,Wenhui Jiang,Lixiang Wang,Guoshun Pei,Qingang Hu,Claude Prigent

doi:10.1371/journal.pone.0079336

Abstract

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase critically involved in cancer metastasis. We found an elevation of FAK expression in highly metastatic melanoma B16F10 cells compared with its less metastatic partner B16F1 cells. Down-regulation of the FAK expression by either small interfering RNA or dominant negative FAK (FAK Related Non-Kinase, FRNK) inhibited the B16F10 cell migration in vitro and invasiveness in vivo. The mechanism by which FAK activity is up-regulated in highly metastatic cells remains unclear. In this study, we reported for the first time that one of the Est family proteins, PEA3, is able to transactivate FAK expression through binding to the promoter region of FAK. We identified a PEA3-binding site between nucleotides −170 and +43 in the FAK promoter that was critical for the responsiveness to PEA3. A stronger affinity of PEA3 to this region contributed to the elevation of FAK expression in B16F10 cells. Both in vitro and in vivo knockdown of PEA3 gene successfully mimicked the cell migration and invasiveness as that induced by FAK down-regulation. The activation of the well-known upstream of PEA3, such as epidermal growth factor, JNK, and ERK can also induce FAK expression. Furthermore, in the metastatic human clinic tumor specimens from the patients with human primary oral squamous cell carcinoma, we observed a strong positive correlation among PEA3, FAK, and carcinoma metastasis. Taking together, we hypothesized that PEA3 might play an essential role in the activation of the FAK gene during tumor metastasis.

Highlights

Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase that plays critical roles in integrin-mediated signal transductions and participates in growth factor receptor signaling [1,2,3]
When B16F1 and B16F10 cells were intravenously injected into mice, a significant increase of lung metastatic nodules were developed in mice injected with B16F10 cells than that in mice injected with B16F1 cells (Fig. 1A-1&Fig. 1A-2,***P,0.001)
We have provided evidence that PEA3induced FAK expression is necessary for melanoma cell migration and metastasis

Summary

Introduction

Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase that plays critical roles in integrin-mediated signal transductions and participates in growth factor receptor signaling [1,2,3]. FAK-mediated signaling largely depends on its kinase activity and associated protein–protein interactions. After integrin clustering, FAK binds to the cytoplasmic tail of b-integrin and results in phosphorylation of FAK tyrosine Y397 [6,7]. Such auto-phosphorylation of Y397 generates a highaffinity binding site for Src. The interaction with Src results in ERK MAPK activation to initiate proliferation [8,9]. Once further phosphorylated by Src, FAK can recruit Jun N-terminal kinase (JNK) to focal adhesion sites and the JNK pathway is implicated in promoting FAK-initiated signals controlling tumor cell invasion [10,11]

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Results

Conclusion