title: 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.
authors.affiliation: Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine, Peoria, IL 61605, USA.
authors.forename: D
authors.initials: D
authors.lastname: Kesanakurti
authors.forename: C
authors.initials: C
authors.lastname: Chetty
authors.forename: D
authors.initials: D
authors.lastname: Rajasekhar Maddirela
authors.forename: M
authors.initials: M
authors.lastname: Gujrati
authors.forename: J S
authors.initials: JS
authors.lastname: Rao
mesh_terms: D000818:Animals; D023102:Anoikis; D045744:Cell Line, Tumor; D002465:Cell Movement; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D005910:Glioma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000235:genetics / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D011485:Protein Binding; D015398:Signal Transduction; D014183:Transplantation, Heterologous; D054462:p21-Activated Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D039302:Integrin alphaVbeta3; C116367:PAK4 protein, human; D066246:ErbB Receptors; D054462:p21-Activated Kinases; D020778:Matrix Metalloproteinase 2