Abstract 1468: MTA2 enhances breast cancer metastasis via regulation of the cytoskeleton and rho signaling pathways

Abstract

Abstract Metastasis tumor associated (MTA) 2 is a component of the nucleosome remodeling and histone deacetylation complex and is implicated in regulating gene expression through its associated histone deacetylase activity. We have previously found that MTA2 enhanced the anchorage independent growth phenotype of estrogen receptor alpha (ER)-positive cells, implicating a potential role in metastasis. As MTA2-overexpression in these cells also resulted in an estrogen independent phenotype, we hypothesized that MTA2-overexpression may similarly enhance the aggressiveness of ER-negative cells. We found that MTA2-overexpressing MDA-MB-231 cells were more invasive through Matrigel, had enhanced soft-agar colony formation activity compared with vector controls, and demonstrated increased migration in wound healing assays. Furthermore, we found that MTA2 overexpression resulted in rapid systemic metastases when grown as orthotopic xenografts, while vector control cells failed to form metastases, in the same time period. Microarray analysis revealed enrichment for genes regulating the cytoskeleton and cell-environment interactions, which was validated using a previously published microarray dataset. We found that the negative regulator of the Rho pathway, Rho GDP dissociation inhibitor alpha (RhoGDI-alpha), was also decreased in expression at the protein level in the MTA2-overexpressing MDA-MB-231 cells. We found that blocking signaling through the Rho pathway by either using a Rho Kinase inhibitor or by overexpressing RhoGDI-alpha significantly reduced the soft-agar colony forming ability of MTA2-overexpressing cells. We examined the effect of MTA2 and RhoGDI-alpha expression in a retrospective breast cancer microarray dataset and found that patients classified as MTA2-high and RhoGDI-alpha-low had significantly earlier recurrence compared with all other patients. These data indicate that MTA2-overexpression results in an increase in the metastatic potential of breast cancer cells. These results have potential clinical implications as patients who have the MTA2-high/RhoGDI-alpha-low phenotype are at increased risk for early recurrence. In conclusion, our data show that MTA2 and RhoGDI-alpha enhances breast cancer metastasis possibly by promoting invasiveness and anchorage independent growth and survival. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1468. doi:10.1158/1538-7445.AM2011-1468