Conformational Changes and Translocation of Tissue-Transglutaminase to the Plasma Membranes: Role in Cancer Cell Migration

Author(s)

Ambrish Kumar, University of South Carolina - ColumbiaFollow
Jianjun Hu, University of South Carolina - ColumbiaFollow
Holly A. LaVoie, University of South Carolina - ColumbiaFollow
Kenneth B. Walsh, University of South Carolina - ColumbiaFollow
Donald J. DiPette, University of South Carolina - ColumbiaFollow
Ugra S. Singh, University of South Carolina - ColumbiaFollow

Document Type

Article

Subject Area(s)

Cancer Research, Genomics

Abstract

Background

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.

Methods

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 (SHY_TG2), 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.

Results

TG2 containing cells (SHY_TG2 and pancreatic cancer cells) exhibit increased cell migration and invasion in collagen-coated and matrigel-coated transwell plate assays, respectively. Resveratrol (1 μM-10 μM) 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.

Conclusions

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.

Publication Info

Published in BMC Cancer, Volume 14, Issue 256, 2014.

Rights

© BMC Cancer 2014, BioMed Central

Kumar, A., Hu, J., LaVoie, H. A., Walsh, K. B., DiPette, D. J., & Singh, U. S. (2014). Conformational changes and translocation of tissue-transglutaminase to the plasma membranes: role in cancer cell migration. BMC Cancer, 14(256).

http://dx.doi.org/10.1186/1471-2407-14-256

Link to License:

http://creativecommons.org/licenses/by/4.0/legalcode