Breast Cancer Research Today is a free monthly online journal that collates and summarizes the latest research about Breast Cancer, including details on symptoms, genetics, screening, treatment, information.

Nm23-H1 suppresses tumor cell motility by down-regulating the lysophosphatidic acid receptor EDG2.

Horak CE, Lee JH, Elkahloun AG, Boissan M, Dumont S, Maga TK, Arnaud-Dabernat S, Palmieri D, Stetler-Stevenson WG, Lacombe ML, Meltzer PS, Steeg PS

Women's Cancer Section, Laboratory of Molecular Pharmacology, National Cancer Institute/NIH, 37 Convent Drive, Bethesda, MD 20892, USA. horakc@mail.nih.gov

Exogenous overexpression of the metastasis suppressor gene Nm23-H1 reduces the metastatic potential of multiple types of cancer cells and suppresses in vitro tumor cell motility and invasion. Mutational analysis of Nm23-H1 revealed that substitution mutants P96S and S120G did not inhibit motility and invasion. To elucidate the molecular mechanism of Nm23-H1 motility suppression, expression microarray analysis of an MDA-MB-435 cancer cell line overexpressing wild-type Nm23-H1 was done and cross-compared with expression profiles from lines expressing the P96S and S120G mutants. Nine genes, MET, PTN, SMO, FZD1, L1CAM, MMP2, NETO2, CTGF, and EDG2, were down-regulated by wild-type but not by mutant Nm23-H1 expression. Reduced expression of these genes coincident with elevated Nm23-H1 expression was observed in human breast tumor cohorts, a panel of breast carcinoma cell lines, and hepatocellular carcinomas from control versus Nm23-M1 knockout mice. The functional significance of the down-regulated genes was assessed by transfection and in vitro motility assays. Only EDG2 overexpression significantly restored motility to Nm23-H1-suppressed cancer cells, enhancing motility by 60-fold in these cells. In addition, silencing EDG2 expression with small interfering RNA reduced the motile phenotype of metastatic breast cancer cells. These data suggest that Nm23-H1 suppresses metastasis, at least in part, through down-regulation of EDG2 expression.

Published 2 August 2007 in Cancer Res, 67(15): 7238-46.
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