Nm23-H1 suppresses tumor cell motility by down-regulating the lysophosphatidic acid receptor EDG2.
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.
Women's Cancer Section, Laboratory of Molecular Pharmacology, National Cancer Institute/NIH, 37 Convent Drive, Bethesda, MD 20892, USA. horakc@mail.nih.gov
Christine E
CE
Horak
Jong Heun
JH
Lee
Abdel G
AG
Elkahloun
Mathieu
M
Boissan
Sylvie
S
Dumont
Tara K
TK
Maga
Sandrine
S
Arnaud-Dabernat
Diane
D
Palmieri
William G
WG
Stetler-Stevenson
Marie-Lise
ML
Lacombe
Paul S
PS
Meltzer
Patricia S
PS
Steeg
D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002465:Cell Movement; D015331:Cohort Studies; D003094:Collagen / Q000378:metabolism; D015536:Down-Regulation; D004338:Drug Combinations; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D020868:Gene Silencing; D006801:Humans; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D007797:Laminin / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D054778:NM23 Nucleoside Diphosphate Kinases; D009701:Nucleoside-Diphosphate Kinase / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D011509:Proteoglycans / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D049368:Receptors, Lysophosphatidic Acid / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D004338:Drug Combinations; D007797:Laminin; D054778:NM23 Nucleoside Diphosphate Kinases; D011509:Proteoglycans; D012333:RNA, Messenger; D049368:Receptors, Lysophosphatidic Acid; C059485:matrigel; D003094:Collagen; C517938:NME1 protein, human; C517939:Nme1 protein, mouse; D009701:Nucleoside-Diphosphate Kinase