Elevation of breast carcinoma Nm23-H1 metastasis suppressor gene expression and reduced motility by DNA methylation inhibition

• Published in: Cancer research (Chicago, Ill.) Vol. 61; no. 5; pp. 2320 - 2327
• Main Authors: HARTSOUGH, Melanie T, CLARE, Susan E, MAIR, Michael, ELKAHLOUN, Abdel G, SGROI, Dennis, OSBORNE, C. Kent, CLARK, Gary, STEEG, Patricia S
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01-03-2001
• Subjects: 5-aza-2'-deoxycytidine; Antimetabolites, Antineoplastic - pharmacology; Antineoplastic agents; Azacitidine - analogs & derivatives; Azacitidine - pharmacology; Biological and medical sciences; Breast Neoplasms - genetics; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Carcinoma, Ductal, Breast - genetics; Carcinoma, Ductal, Breast - metabolism; Carcinoma, Ductal, Breast - pathology; Cell Movement - genetics; Chemotherapy; CpG Islands - genetics; DNA Methylation - drug effects; Gene Expression Regulation, Neoplastic - physiology; Genes, Tumor Suppressor; Humans; Medical sciences; Monomeric GTP-Binding Proteins - biosynthesis; Monomeric GTP-Binding Proteins - genetics; Neoplasm Metastasis; NM23 Nucleoside Diphosphate Kinases; Nm23-H1 gene; Nucleoside-Diphosphate Kinase; Pharmacology. Drug treatments; Promoter Regions, Genetic - genetics; Transcription Factors - biosynthesis; Transcription Factors - genetics; Transfection; Tumor Cells, Cultured; Antineoplastic agent; Human; Carcinoma; Gene product; Transcription promoter; Tumoral tissue; Mobility; Gene overexpression; Potential; Malignant tumor; Gene expression; In vitro; Biological activity; Mammary gland diseases; Deoxycytidine; GC rich sequence; DNA; Metastasis suppressor gene; Established cell line; Inhibitor; Metastatic; Mammary gland; Methylation; Tumor cell
• ISSN: 0008-5472; 1538-7445

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.