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Clin Exp Metastasis. 2017 Jan;34(1):37-49. doi: 10.1007/s10585-016-9827-5. Epub 2016 Oct 21.

Extracellular matrix 1 (ECM1) regulates the actin cytoskeletal architecture of aggressive breast cancer cells in part via S100A4 and Rho-family GTPases.

Author information

1
Division of Surgical Oncology and Endocrine Surgery, Department of Surgery, University of Iowa, 200 Hawkins Drive, 4641 JCP, Iowa City, IA, 52242, USA.
2
Department of Physiology, Georgia Regents University, Augusta, GA, USA.
3
Department of Internal Medicine, University of Iowa, Iowa City, IA, USA.
4
Department of Biology, University of Iowa, Iowa City, IA, USA.
5
Free Radical and Radiation Biology, University of Iowa, Iowa City, IA, USA.
6
Division of Surgical Oncology and Endocrine Surgery, Department of Surgery, University of Iowa, 200 Hawkins Drive, 4641 JCP, Iowa City, IA, 52242, USA. Geeta-lal@uiowa.edu.

Abstract

ECM1 overexpression is an independent predictor of poor prognosis in primary breast carcinomas, however the mechanisms by which ECM1 affects tumor progression have not been completely elucidated. ECM1 was silenced in the triple-negative breast cancer cell lines Hs578T and MDAMB231 using siRNA and the cells were evaluated for changes in morphology, migration, invasion and adhesion. Actin cytoskeleton alterations were evaluated by fluorescent staining and levels of activated Rho GTPases by pull down assays. ECM1 downregulation led to significantly diminished cell migration (p = 0.0005 for Hs578T and p = 0.02 for MDAMB231) and cell adhesion (p < 0.001 for Hs578T and p = 0.01 for MDAMB231). Cell invasion (matrigel) was reduced only in the Hs578T cells (p < 0.01). Silencing decreased the expression of the prometastatic molecules S100A4 and TGFβR2 in both cell lines and CD44 in Hs578T cells. ECM1-silenced cells also exhibited alterations in cell shape and showed bundles of F-actin across the cell (stress fibers) whereas NT-siRNA treated cells showed peripheral membrane ruffling. Downregulation of ECM1 was also associated with an increased F/G actin ratio, when compared to the cells transfected with NT siRNA (p < 0.001 for Hs578T and p < 0.00035 for MDAMB231) and a concomitant decline of activated Rho A in the Hs578T cells. Re-expression of S100A4 in ECM1-silenced cells rescued the phenotype in the Hs578T cells but not the MDAMB231 cells. We conclude that ECM1 is a key player in the metastatic process and regulates the actin cytoskeletal architecture of aggressive breast cancer cells at least in part via alterations in S100A4 and Rho A.

KEYWORDS:

Actin cytoskeleton; ECM1; Metastasis; Rho A; S100A4

PMID:
27770373
PMCID:
PMC5288287
DOI:
10.1007/s10585-016-9827-5
[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

The authors have no competing interests

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