Functional cooperativity by direct interaction between PAK4 and MMP-2 in the regulation of anoikis resistance, migration and invasion in glioma

Abstract

Gliomas display anoikis resistance, enhanced invasion in to the adjacent brain parenchyma and eventually recur despite using the standard therapies. Our studies on increased anoikis sensitization in matrix metalloproteinase-2 (MMP-2)-knockdown 4910 and 5310 human glioma xenograft cells were interestingly correlated with p21-activated kinase 4 (PAK4) inhibition, prompting us to further investigate the role of PAK4 in glioma. Here, we report the PAK4 upregulation in positive correlation with increasing glioma pathological grades. The siRNA-mediated PAK4 knockdown elevated anoikis, and inhibited invasion and migration by downregulating MMP-2, αvβ3-integrin and phospho-epidermal growth factor receptor (phospho-EGFR). The cDNA-PCR arrays revealed a transcriptional suppression of essential proteins involved in cell proliferation and adhesion in PAK4-knockdown cells. Most importantly, glutathione S-transferase pull-down assays demonstrated the MMP-2 as a new PAK4-interacting protein which binds to PAK4 kinase domain. Individual EGFR/ErbB2 inhibitor and αvβ3 antibody treatments in PAK4si-treated cells indicated the regulation of αvβ3/EGFR survival signaling by PAK4. Overexpression of PAK4 significantly reversed the MMP2si-induced cell death in both cell lines. Codepletion of PAK4 and MMP-2 resulted in robust anoikis-mediated cell death, and severely inhibited invasive and migratory properties in these cells. PAK4si inhibited in vivo tumor growth in nude mice by inhibiting MMP-2, β3-integrin and phospho-EGFR levels in tumors. Our findings indicate a physical association between PAK4 and MMP-2, and suggest the future therapeutic potential of PAK4/MMP-2 dual targeting in glioma treatment.

Increased expression of p21-activated kinase 4 in adenomyosis and its regulation of matrix metalloproteinase-2 and -9 in endometrial cells

“…Kesanakurti et al (11) observed that siRNA-mediated Pak4 knockdown inhibited invasion and migration by down-regulating MMP-2 in a human glioma model using xenograft cells. These findings are in agreement with our results in that the activity of Pak4 directly influences the expression of MMPs in endometrial tissues, and this may implicate Pak4 as an important biological promoter of the invasion of endometrial cells through regulation of the expression and/or activity of MMPs.…”

“…Furthermore, several studies have demonstrated that increased expression of Pak4 is correlated with tumor progression or metastasis (10,11). We previously found that Pak4 immunoreactivity is significantly higher in the eutopic endometrium as well as ovarian endometrioma of women with advanced-stage endometriosis compared with control subjects (12).…”

Activated Pak4 expression correlates with poor prognosis in human gastric cancer patients

“…Pak4 is overexpressed and/or highly activated in various human cancer tissues and cell lines, including the lung, liver, choriocarcinoma, glioma, colon, breast, endometrial, ovary, prostate, pancreas, and GC [18,19,14,20,12,[21][22][23][24]. Several studies have assessed the prognostic value and therapeutic potential of Pak4 in reproductive cancers.…”

MicroRNA-433 inhibits cell proliferation in hepatocellular carcinoma by targeting p21 activated kinase (PAK4)

“…Among them, p21-activated kinase 4 (PAK4), a specific receptor of Cdc42 and Rac, is of great interest because it does not only play roles in normal cellular functions, but also implicate in tumorigenesis when being overexpressed [4]. Increasing data have suggested that the aberrant expression of PAK4 is closely related to the progression and development of ovarian, prostate, breast cancers, colon and gastric cancers, choriocarcinoma, and glioma [5][6][7]. Moreover, the phosphorylation of PAK4 at ser474 was also found to be increased in human HCC cell lines including MHCC97H, MHCC97L, and HepG2 [8].…”