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-alpha). We show that PP2A-alpha 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-alpha activates CREB, and thereby increases MMP-2 transcription, provides novel mechanistic insight into the pro- metastatic function of TG2.
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ABSTRACT: Transglutaminases (TGs) are multifunctional proteins having enzymatic and scaffolding functions that participate in regulation of cell fate in a wide range of cellular systems and are implicated to have roles in development of disease. This review highlights the mechanism of action of these proteins with respect to their structure, impact on cell differentiation and survival, role in cancer development and progression, and function in signal transduction. We also discuss the mechanisms whereby TG level is controlled and how TGs control downstream targets. The studies described herein begin to clarify the physiological roles of TGs in both normal biology and disease states.Physiological Reviews 04/2014; 94(2):383-417. DOI:10.1152/physrev.00019.2013 · 29.04 Impact Factor
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ABSTRACT: Tissue-transglutaminase (TG2), a dual function G-protein, plays key roles in cell differentiation and migration. In our previous studies we reported the mechanism of TG2-induced cell differentiation. In present study, we explored the mechanism of how TG2 may be involved in cell migration. To study the mechanism of TG2-mediated cell migration, we used neuroblastoma cells (SH-SY5Y) which do not express TG2, neuroblastoma cells expressing exogenous TG2 (SHYTG2), and pancreatic cancer cells which express high levels of endogenous TG2. Resveratrol, a natural compound previously shown to inhibit neuroblastoma and pancreatic cancer in the animal models, was utilized to investigate the role of TG2 in cancer cell migration. Immunofluorescence assays were employed to detect expression and intracellular localization of TG2, and calcium levels in the migrating cells. Native gel electrophoresis was performed to analyze resveratrol-induced cellular distribution and conformational states of TG2 in migrating cells. Data are presented as the mean and standard deviation of at least 3 independent experiments. Comparisons were made among groups using one-way ANOVA followed by Tukey-Kramer ad hoc test. TG2 containing cells (SHYTG2 and pancreatic cancer cells) exhibit increased cell migration and invasion in collagen-coated and matrigel-coated transwell plate assays, respectively. Resveratrol (1 muM-10 muM) prevented migration of TG2-expressing cells. During the course of migration, resveratrol increased the immunoreactivity of TG2 without affecting the total TG2 protein level in migrating cells. In these cells, resveratrol increased calcium levels, and depletion of intracellular calcium by a calcium chelator, BAPTA, attenuated resveratrol-enhanced TG2 immunoreactivity. In native-polyacrylamide gels, we detected an additional TG2 protein band with slower migration in total cell lysates of resveratrol treated cells. This TG2 form is non-phosphorylated, exclusively present in plasma membrane fractions and sensitive to intracellular Ca2+ concentration suggesting a calcium requirement in TG2-regulated cell migration. Taken together, we conclude that resveratrol induces conformational changes in TG2, and that Ca2+-mediated TG2 association with the plasma membrane is responsible for the inhibitory effects of resveratrol on cell migration.BMC Cancer 04/2014; 14(1):256. DOI:10.1186/1471-2407-14-256 · 3.32 Impact Factor
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ABSTRACT: Transglutaminase 2 (TG2) has been reported to play a role in dendritic cell activation and B cell differentiation after immunization. Its presence and role in T cells, however, has not been explored. In the present study, we determined the expression of TG2 on mouse T cells, and evaluated its role by comparing the behaviors of wild-type and TG2(-/-) T cells after activation. In our results, naïve T cells minimally expressed TG2, which expression was increased after activation. T cell proliferation, expression of activation markers such as CD69 and CD25, and secretions of IL-2 and IFN-γ were suppressed in the absence of TG2, presumably due, in part, to diminished NF-κB activation. These effects on T cells seemed to be reflected in the in vivo immune response, the contact hypersensitivity reaction elicited by DNFB, with lowered peak responses in the TG2(-/-) mice. When splenic T cells from mice immunized with tumor lysate-loaded wild-type dendritic cells were re-challenged ex vivo with the same antigen, the profile of surface markers including CD44, CD62L, and CD127 strongly indicated lesser generation of memory CD8(+) T cells in TG2(-/-) mice. In the TG2(-/-) CD8(+) T cells, moreover, Eomes expression was markedly decreased. These results indicate possible roles of TG2 in CD8(+) T cell activation and CD8(+) memory T cell generation. This article is protected by copyright. All rights reserved.Immunology 03/2014; DOI:10.1111/imm.12282 · 3.74 Impact Factor