Differentially Expressed Proteins in ER+ MCF7 and ER- MDAMB-231 Human Breast Cancer Cells by RhoGDI-α Silencing and Overexpression

Background: The consequence of Rho GDP dissociation inhibitor alpha (RhoGDIα) activity on migration andinvasion of estrogen receptor positive (ER+) and negative (ER-) breast cancer cells has not been studied using theproteomic approach. Changes in expression of RhoGDIα and other proteins interacting directly or indirectly withRhoGDIα in MCF7 and MDA-MB-231, with different metastatic potentials is of particular interest. Materialsand
Methods: ER+ MCF7 and ER- MDA-MB-231 cell lines were subjected to two-dimensional electrophoresis(2-DE) and spots of interest were identified by matrix-assisted laser desorption/ionization time of- flight/timeof-flight (MALDI-TOF/TOF) mass spectrometry (MS) analysis after downregulation of RhoGDIα using shortinterfering RNA (siRNA) and upregulated using GFP-tagged ORF clone of RhoGDIα.
Results: The resultsshowed a total of 35 proteins that were either up- or down-regulated in these cells. Here we identifed 9 and 15proteins differentially expressed with silencing of RhoGDIα in MCF-7 and the MDA-MB-231 cells, respectively.In addition, 10 proteins were differentially expressed in the upregulation of RhoGDIα in MCF7, while only oneprotein was identified in the upregulation of RhoGDIα in MDA-MB-231. Based on the biological functions of theseproteins, the results revealed that proteins involved in cell migration are more strongly altered with RhoGDI-αactivity. Although several of these proteins have been previously indicated in tumorigenesis and invasiveness ofbreast cancer cells, some ohave not been previously reported to be involved in breast cancer migration. Hence,these proteins may serve as useful candidate biomarkers for tumorigenesis and invasiveness of breast cancercells.
Conclusions: Future studies are needed to determine the mechanisms by which these proteins regulate cellmigration. The combination of RhoGDIα with other potential biomarkers may be a more promising approachin the inhibition of breast cancer cell migration.