MMP-2 plays a key role in the degradation of the extracellular matrix and thereby enhances the proliferative, invasive and metastatic potential of cancer cells. MMP-2 knockdown using siRNA (pM) in human glioma xenograft cell lines, 4910 and 5310, sensitized cells to anoikis associated with cleavage of PARP, and caspases 8 and 3. pM-inhibited cell adhesion, invasion and migration correlated with attenuation of EGFR, c-Src and Pak4 phosphorylation. High expression of Pak4 in human glioma cell lines and tumor tissues implicated its essential role in increasing glioma malignancy. Co-immunoprecipitation studies implied that MMP-2 directly interacts by complex formation with EGFR, p130CAS and Pak4 along with αvβ3 integrin and pM treatment disrupted this direct binding. Vitronectin-mediated αvβ3 activation and EGF and rhMMP-2 supplementation counteracted pM-inhibited, Pak4-mediated migration and invasion. Conversely, αvβ3 blocking antibody and ErbB-2/EGFR inhibitor (GW2974) further reduced pM-inhibited, Pak4-mediated invasiveness and migration, thereby suggesting a role of αvβ3 and EGFR in the regulation of Pak4 survival signaling. Individual treatments of pM and led to considerable anoikis in both 4910 and 5310 cells and simultaneous co-depletion MMP-2 and Pak4 resulted in robust increase in anoikis levels. In vivo orthotopic experiments in nude mice revealed decreased tumor size with pM treatment. Immunofluorescence analysis of pSV-tumor sections showed high expression and co-localization of MMP-2/αvβ3, which decreased upon treatment with pM along with significant decrease in phospho-EGFR, phospho-Pak4, Bcl2 and Bcl-xL levels. Our results imply a possible crosstalk between MMP-2 and Pak4 and suggest the potential of targeting both MMP-2 and Pak4 as a future therapeutic approach in glioma therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2085. doi:1538-7445.AM2012-2085