Elevation of breast carcinoma Nm23-H1 metastasis suppressor gene expression and reduced motility by DNA methylation inhibition.
We hypothesize that elevation of Nm23-H1 expression in micrometastatic breast cancer cells may inhibit their metastatic colonization and further invasion, and induce differentiation, thus resulting in a clinical benefit. The current study investigated the possible contribution of DNA methylation to the regulation of Nm23-H1 expression, based on the observation that two CpG islands are present in its promoter. 5-Aza-2'-deoxycytidine (5-Aza-CdR), a DNA methylation inhibitor, increased the Nm23-H1 expression of 5 of 11 human breast carcinoma cell lines in vitro, including 3 of 3 metastatically competent lines. Increased Nm23-H1 expression was accompanied by a reduction in motility in vitro, with minimal effect on proliferation. Both increased Nm23-H1 expression and decreased motility were observed using low (75 nM) concentrations of 5-Aza-CdR. Array analysis of MDA-MB-231 breast carcinoma cells treated with 5-Aza-CdR confirmed the elevation of nm23-H1 mRNA, whereas relatively few other genes exhibited altered expression. Bisulfite sequencing of the two CpG islands in a panel of cell lines and in 20 infiltrating ductal carcinomas revealed that one island (-3090 bp to -3922 bp) exhibited infrequent differential methylation. The data indicate that DNA methylation inhibitors can directly or indirectly cause both elevation of Nm23-H1 expression and decreased function in one aspect of metastasis, motility.
Hartsough
M T
MT
Division of Clinical Sciences, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA. hartso@box-h.nih.gov
Clare
S E
SE
Mair
M
M
Elkahloun
A G
AG
Sgroi
D
D
Osborne
C K
CK
Clark
G
G
Steeg
P S
PS
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002465:Cell Movement / Q000235:genetics*; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D016147:Genes, Tumor Suppressor; D006801:Humans; D020559:Monomeric GTP-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D054778:NM23 Nucleoside Diphosphate Kinases; D009362:Neoplasm Metastasis; D009701:Nucleoside-Diphosphate Kinase; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured
D000964:Antimetabolites, Antineoplastic; D054778:NM23 Nucleoside Diphosphate Kinases; D014157:Transcription Factors; D000077209:Decitabine; C517938:NME1 protein, human; D009701:Nucleoside-Diphosphate Kinase; D020559:Monomeric GTP-Binding Proteins; D001374:Azacitidine