Role of MMP-2 in the regulation of IL-6/Stat3 survival signaling via interaction with α5β1 integrin in glioma

Abstract

MMP-2 plays pivotal role in the degradation of extracellular matrix, and thereby enhances the invasive, proliferative and metastatic potential in cancer. Knockdown of MMP-2 using MMP-2 siRNA (pM) in human glioma xenograft cell lines 4910 and 5310 decreased cell proliferation compared to mock- and pSV-(scrambled vector)treatments, as determined by BrDU incorporation, Ki-67 staining and clonogenic survival assay. Cytokine array and Western blotting using tumor conditioned media displayed modulated secretory levels of various cytokines including GM-CSF, IL-6, IL-8, IL-10, TNF-α, angiogenin, VEGF and PDGF-BB in MMP-2 knockdown cells. Further, cDNA PCR array indicated potential negative regulation of JAK/Stat3 pathway in pM-treated cells. Mechanistically, MMP-2 is involved in complex formation with α5 and β1 integrins and MMP-2 downregulation inhibited α5β1 integrin mediated Stat3 phosphorylation and nuclear translocation. EMSA and ChIP assays showed inhibited Stat3 DNA-binding activity and recruitment at CyclinD1 and c-Myc promoters in pM-treated cells. In individual experiments, IL-6 or siRNA-insensitive MMP-2 overexpression by pM-FL-A141G counteracted and restored the pM-inhibited Stat3 DNA-binding activity suggesting IL-6/Stat3 signaling suppression in pM-treated 4910 and 5310 cells. MMP-2/α5β1 binding is enhanced in rhMMP-2 treatments resulting in elevated Stat3 DNA-binding activity and recruitment on CyclinD1 and c-Myc promoters. Activation of α5β1 signaling by Fibronectin adhesion elevated pM-inhibited Stat3 phosphorylation whereas blocking α5β1 abrogated constitutive Stat3 activation. In vivo experiments with orthotropic tumor model revealed the decreased tumor size in pM-treatment compared to mock- or pSV-treatments. Immunoflorescence studies in tumor sections corroborated our in vitro findings evidencing high expression and co-localization of MMP-2/α5β1, which is decreased upon pM-treatment along with significantly reduced IL-6, phospho-Stat3, CyclinD1, c-Myc, Ki-67 and PCNA expression levels. Our data indicates the possible role of MMP-2/α5β1 interaction in the regulation of α5β1-mediated IL-6/Stat3 signaling activation and signifies the therapeutic potential of blocking MMP-2/α5β1 interaction in glioma treatment.

Non-androgen Signaling Pathways in Castration-Resistant Prostate Cancer

“…STAT3 induces the pro-survival and anti-apoptotic genes such as Bcl-2, Bcl-xl, survivin and Mcl-1 in PCa and other tumors [90]. Additionally, STAT3 induces the expression of vascular endothelial growth factor (VEGF), a pro-angiogenic factor, which in turn is responsible for regulating various matrix metalloproteinases enzymes (MMPs) that augments the migration and invasion of tumor cells [90,[92][93][94][95]. Interestingly, high levels of STAT3 detected in both malignant and normal surrounding tissues suggesting that the activation of STAT3 may occur prior to any detectable histological changes in the prostate [96].…”

Prognostic Significance of α5β1-integrin Expression in Cervical Cancer

“…Recent research report that α5β1-integrin plays an important role in stimulating endothelial cell proliferation at an early step in the angiogenic process (Li et al, 2012). Secondly, α5β1-integrin may partake in activating MMP-2 Morozevich et al, 2009;Shi et al, 2011;Kesanakurti et al, 2012;Zhu et al, 2013). Invasion and metastasis of cancer have a close relationship with basement membrane adhesion and extracellular matrix degradation.…”

Clinicopathological and Prognostic Significance of α5β1-integrin and MMP-14 Expressions in Colorectal Cancer

“…This indicated that integrin and MMPs had mutual effect .These findings suggested that α5β1-integrin plays a functional role in the invasion of studied cells, perhaps by triggering a signaling pathway controlling the activity of MMP-14 gene. Most importance was that α5β1-integrin and MMP-14 also have the common functions of activating MMP-2 [39][40][41][42] and stimulating tumor angiogenesis [25,43]. The α5β1-integrin and MMP-14 could promote each other in tumor with invasion and metastasis process and act synergistically.…”