Tissue Transglutaminase Regulates Matrix Metalloproteinase-2 in Ovarian Cancer by Modulating cAMP-response Element-binding Protein Activity

Abstract

Tissue transglutaminase 2 (TG2) is overexpressed in epithelial ovarian cancer (EOC) and promotes intraperitoneal metastasis. How TG2 facilitates the spread of EOC is unknown. Here, we show that TG2 regulates the expression and function of matrix metalloproteinase-2 (MMP-2), a critical mediator of tissue invasiveness. TG2 knockdown down-regulates MMP-2 protein and mRNA expression in SKOV3, IGROV-1, MDA-MB-436, and PC-3 cancer cells. TG2 knockdown or inhibition of TG2 activity using KCC009 decreases MMP-2 gelatinase activity in cancer cells. MMP-2 expression and function are regulated by TG2 at transcriptional level, as demonstrated by quantitative PCR and reporter assays. We used bioinformatics and chromatin immunoprecipitation to identify a CREB binding site in the MMP-2 promoter. Binding of CREB to the MMP-2 promoter was diminished in cells that expressed decreased TG2 levels. TG2 knockdown decreased CREB phosphorylation, and CREB knockdown decreased MMP-2 expression. The effect of TG2 on CREB activity and MMP-2 transcription is mediated by TG2-dependent degradation of protein phosphatase 2 (PP2A-␣). We show that PP2A-␣ complexes with and is targeted for degradation by TG2. In addition to their related in vitro expression levels, TG2 and MMP-2 expression were significantly correlated in vivo, as shown by concordant immunostaining in peritoneal xenografts and in human ovarian tumors. The capacity of TG2 to regulate MMP-2 expression in vitro and in vivo identifies a mechanism that may facilitate tissue invasion and the spread of EOC. The demonstration that TG2 induced degradation of PP2A-␣ activates CREB, and thereby increases MMP-2 transcription, provides novel mechanistic insight into the prometastatic function of TG2.Transglutaminase 2 (TG2), 2 an enzyme overexpressed in epithelial malignancies (1, 2), cross-links proteins by acyltransfer between glutamine and lysine residues and participates in Ca 2ϩ -dependent post-translational protein modification by incorporating polyamines into peptide chains (3). We recently reported that TG2 is up-regulated in transformed ovarian epithelial cells and tumors compared with normal cells, and facilitates peritoneal dissemination of EOC cells (1, 4). TG2 has multiple functions. It strengthens integrin-dependent cell adhesion, modulates intracellular signaling, and remodels the extracellular matrix through protein cross-linking (5). To understand the involvement of TG2 in the process of intraperitoneal metastasis, we investigated its involvement in the regulation of proteins known to facilitate tumor invasion and spread.Matrix metalloproteinases (MMPs) are a family of secreted proteins that remodel and digest the extracellular matrix. In the context of malignancy, MMPs play a prominent role in metastasis and angiogenesis (6), because degradation of the extracellular matrix in the immediate vicinity of a tumor niche facilitates cancer cell invasion and escape from the primary tumor site (7,8). Regulation of MMP activity occurs at different levels (9). MMPs are secreted as pro...

HER-2/neu Mediates Oncogenic Transformation via Altered CREB Expression and Function

“…This was associated with a reduced activity of the MMP promoters, which was dependent on putative CREB-or CRE-binding sites. Modulation of MMP-2 and -9 promoter activity by CREB has also been shown in different cell systems (49)(50)(51). Furthermore, the transcriptional upregulation of MMP-2 and -9 by CREB not only increased their invasion potential in vitro and in vivo, but also enhanced angiogenesis in vivo (52), which was not addressed in the present study.…”

Epidermal Growth Factor Receptor-mediated Tissue Transglutaminase Overexpression Couples Acquired Tumor Necrosis Factor-related Apoptosis-inducing Ligand Resistance and Migration through c-FLIP and MMP-9 Proteins in Lung Cancer Cells

“…Suppression of MMP-9 expression with siRNA substantially inhibited cell migration/invasion, suggesting that MMP-9 is one of the major MMPs that contribute to acquired TRAIL resistance-associated migration/ invasion. Although regulated by TGM2 in certain cancer cell types, other MMPs such as MMP-2 are unlikely involved in migration in the lung cancer cells with acquired TRAIL resistance (36). This observation suggests that the mechanisms of TGM2 in cancer cell migration/invasion are cell type-specific or that the functioning mechanism of TGM2 in acquired TRAIL resistance-associated migration/invasion is distinct to that in cancer cells with primary apoptosis resistance.…”

“…It has been shown that TGM2 promotes cell growth, survival, and motility or invasion (38,39). Although increased TGM2 expression in cancer cells has been linked to increased drug resistance, metastasis, and poor patient survival (36,37,40), to our knowledge, this is the first report showing that TGM2 is overexpressed when acquired TRAIL resistance arises with the association of increased cell migration and invasion. Although the regulation of TGM2 expression is complex, EGFR-mediated cell signaling is implicated in up-regulation of TGM2 expression in cancer cells (32).…”

Colorectal Carcinogenesis: Connecting K-RAS–Induced Transformation and CREB Activity In Vitro and In Vivo

“…This was dependent on CREB because mutations of the three putative CREB-binding sites in the MMP-9 promoter resulted in a significantly decreased activity, while a deletion of the single CRE site decreased the MMP-2 promoter activity by 20%. Although the binding of CREB to the MMP-2 and MMP-9 promoter had already been shown in different studies (43,44), this effect has not yet been linked to RAS transformation. These data are in line with reports demonstrating that CREB protein elimination decreased the activities of MMP in NSCLC (45) and melanoma (42).…”