PAK5-mediated E47 phosphorylation promotes epithelial–mesenchymal transition and metastasis of colon cancer

Abstract

The p21-activated kinase 5 (PAK5) is overexpressed in advanced cancer and the transcription factor E47 is a direct repressor of E-cadherin and inducer of epithelial-mesenchymal transition (EMT). However, the relationship between PAK5 and E47 has not been explored. In this study, we found that PAK5-mediated E47 phosphorylation promoted EMT in advanced colon cancer. PAK5 interacted with E47 and phosphorylated E47 on Ser39 under hepatocyte growth factor (HGF) stimulation, which decreased cell-cell cohesion, increased cell migration and invasion in vitro and promoted metastasis in a xenograft model. Furthermore, phosphorylation of E47 facilitated its accumulating in nucleus in an importin α-dependent manner, and enhanced E47 binding to E-cadherin promoter directly, leading to inhibition of E-cadherin transcription. In contrast, PAK5-knockdown resulted in blockage of HGF-induced E47 phosphorylation, attenuated association of E47 with importin α and decreased E47 binding to E-cadherin promoter. In addition, we demonstrated a close correlation between PAK5 and phospho-Ser39 E47 expression in colon cancer specimens. More importantly, high expression of phospho-E47 was associated with an aggressive phenotype of colon cancer and nuclear phospho-E47 staining was found in certain cases of colon cancer with metastasis. Collectively, E47 is a novel substrate of PAK5, and PAK5-mediated phosphorylation of E47 promotes EMT and metastasis of colon cancer, suggesting that phosphorylated E47 on Ser39 may be a potential therapeutic target in progressive colon cancer.

Structure, biochemistry, and biology of PAK kinases

“…PAK5 phosphorylation of BAD on Ser112 inhibits apoptosis (Cotteret et al, 2003; Wang et al, 2010). PAK5 phosphorylation of GATA-1 on Ser161 and Ser187 causes epithelial-to-mesenchymal transition in breast cancer cells, phosphorylation of E47 on Ser39 promotes colon cancer metastasis (Li et al, 2015b; Zhu et al, 2016), and phosphorylation of p120-catenin-Ser288 facilitates cytoskeleton reorganization with implications in cancer cell motility and invasion (Wong et al, 2012).…”

A PAK5–DNPEP–USP4 axis dictates breast cancer growth and metastasis

“…Studies indicate that p21‐activated kinase 5 (PAK5), the most recently identified member of the PAK family, plays an indispensable role in regulation of the cytoskeleton, microtubule stability and cell survival . Increasing lines of evidence suggest that PAK5 is an oncogenic protein that is commonly overexpressed in many cancer tissues and contributes to the progression of diverse cancers . Likewise, in human breast cancer, PAK5 has been shown to activate a PAK5–early growth response protein 1 (Egr1)–matrix metalloproteinase 2 (MMP2) pathway to control cell migration and invasion .…”

“…5,6 Increasing lines of evidence suggest that PAK5 is an oncogenic protein that is commonly overexpressed in many cancer tissues and contributes to the progression of diverse cancers. [7][8][9][10][11] Likewise, in human breast cancer, PAK5 has been shown to activate a PAK5-early growth response protein 1 (Egr1)-matrix metalloproteinase 2 (MMP2) pathway to control cell migration and invasion. 12 PAK5-directed GATA1 phosphorylation has been reported to induce epithelialmesenchymal transition in breast cancer cells.…”

Negative Glucocorticoid Response-Like Element from the First Intron of the Chicken Growth Hormone Gene Represses Gene Expression in the Rat Pituitary Tumor Cell Line

“…There were 32 types of TFBSs within the first intron fragment, including the enhancers, i.e., CCAAT/enhancer binding protein beta (CEBPB), CCAAT/enhancer binding protein alpha (CEBP), cAMP activated protein (CAP), GATA binding elements (GATA1), LIM-only protein 2 (LMO2COM), myeloid zinc finger 1 (MZF1), simian-virus-40-protein-1 (SP1), basic helix–loop–helix transcription factors (USF), the repressor, acute myeloid leukemia-1 (AML1), and the enhancers or repressor GRE [17,31]. There were also some elements with unclear functions, i.e., AP1, replication initiator 1 (AP4), AP1FJ, c-Ets-1 (CETS1P54), c-Rel (CREL), caudal type homeobox 1 (CDXA), DELTAEF1, cyclin E/E2F (E2F), E47, GATA3, GATA2, hepatocyte nuclear factor 3β (HNF3β), ikappa B kinase-like 2 (IK2), c-Myb (MYB), MYOD, cardiac-specific homeobox protein (NKX25), OCT1, P53, sex-determining region Y (SRY), STAT, TATA, and TST1 [32,33,34,35,36] (Table S1). The 5′-distal region of +55/+372 in the cGH contained a cluster of twenty TFBSs and highly conserved near-consensus TFBSs (score = 1.000) for the transcriptional factor, which was acute myeloid leukemia-1 (AML1).…”