OBJECTIVETo investigate the expression of RhoC in breast cancer cells with different metastatic potential and its correlation with invasiveness.

METHODSExpression of RhoC mRNA and protein in human breast cancer cells MCF-7 with low metastatic potential and MDA-MB-231 with high metastatic potential was detected by RT-PCR, Western blot, immunohistochemistry and immunofluorescence staining. Eukaryotic expression plasmids of RhoC were constructed and transfected into MCF-7 cells. The biological effects were observed, including in vitro invasion by Boyden charmber assay, motility by would healing assay, alteration of microfilament network by TRTIC-phalloidin staining and expression of p-Akt by Western blot assay.

RESULTSThe expression levels of RhoC mRNA and protein varied in the two different metastatic breast cancer cell lines. RhoC was significantly up-regulated in the highly metastatic cells in comparison to the weakly metastatic counterpart (P < 0.01). As shown by Boyden charmber assay, the invasive capacity of transfected cells overexpressing RhoC was significantly promoted as reflected by more penetrating cells (56.88 +/- 4.18) than that of the antisense transcripts (23.12 +/- 3.22), the negative (23.77 +/- 3.64) and blank controls (28.44 +/- 2.48). Further study by would healing assay indicated that cells overexpressing RhoC were more motile in actin-based active movement. The wound healing ratio after 24 h of the sense transcripts, antisense transcripts, negative controls and blank controls was 58.28% +/- 2.14%, 22.36% +/- 2.73%, 28.23% +/- 2.62%, 30.18% +/- 2.86%, respectively. The TRITC-phalloidin staining revealed less actin filament bundles and a reorganized cytoskeleton within the sense transcripts. In addition, p-Akt expression level was upregulated in the sense transcripts.

CONCLUSIONRhoC overexpression may promote the invasive capacity of human breast cancer cells in vitro and its expression level is positively correlated with the metastatic capacity of those cells. So RhoC may be a potential target in the development of a novel strategy for treating metastasis of breast cancer.

Breast Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Cell Movement ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; Neoplasm Invasiveness ; Phosphorylation ; Plasmids ; Proto-Oncogene Proteins c-akt ; metabolism ; RNA, Messenger ; metabolism ; Transfection ; Up-Regulation ; rho GTP-Binding Proteins ; genetics ; metabolism ; rhoC GTP-Binding Protein