High-frequency promoter hypermethylation of the deleted in liver cancer-1 gene in multiple myeloma.
BACKGROUND
Deleted in liver cancer-1 (DLC-1) is a tumour suppressor gene that is inactive in liver carcinogenesis. It encodes a rho-guanosine triphosphatase-activating protein (rho-GAP) and maps to one of the deleted regions (8p21.3-22). Little is known, however, about the methylation status of the DLC-1 promoter in myeloma cells.


OBJECTIVE
To identify whether methylation of DLC-1 was associated in pathogenesis of multiple myeloma.


METHODS
Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect DLC-1 transcripts in RPMI 8226, U266, OPM-2 and XG-2 cell lines. The methylation status was determined by methylation-specific PCR followed by bisulphite DNA sequencing in these four cell lines and in the bone marrow of 14 patients with multiple myeloma and 4 normal patients. DLC-1 mRNA expression in cells with or without treatment with 5-aza-deoxycytidine (5-aza-CdR) or trichostatin A (TSA) was investigated by real-time RT-PCR.


RESULTS
RPMI 8226 and U266 showed complete methylation and XG-2 showed partial methylation. DLC-1 was expressed only in OPM-2 cell lines that showed no methylation. DLC-1 methylation was shown in 11 of 14 (78%) patients with multiple myeloma and none of the normal controls. The exposure of cell lines to 5-aza-CdR or TSA resulted in the up regulation of DLC-1 gene expression.


CONCLUSIONS
DLC-1 methylation is often present in multiple myeloma and has a key role in DLC-1 silencing.
Department of Hematology, Hua Shan Hospital, Fu Dan University, Shanghai, China. songyf03@yahoo.com
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YF
Song
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Xu
X-H
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Zhang
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BB
Chen
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Chen
Y-M
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Chen
Y
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Xie
D001374:Azacitidine / Q000031:analogs & derivatives; D001483:Base Sequence; D001853:Bone Marrow / Q000378:metabolism; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors; D000077209:Decitabine; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D020690:GTPase-Activating Proteins; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000235:genetics* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
C112352:DLC1 protein, human; D004791:Enzyme Inhibitors; D020690:GTPase-Activating Proteins; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D025521:Tumor Suppressor Proteins; C012589:trichostatin A; D000077209:Decitabine; D015254:DNA Modification Methylases; D001374:Azacitidine