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SPAN‐Xb expression in myeloma cells is dependent on promoter hypomethylation and can be upregulated pharmacologically
Author(s) -
Wang Zhiqing,
Zhang Jian,
Zhang Yana,
Lim Seah H
Publication year - 2005
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.21499
Subject(s) - cpg site , dna methylation , methylation , microbiology and biotechnology , biology , gene expression , bisulfite sequencing , regulation of gene expression , promoter , gene , genetics
SPAN‐Xb is a novel cancer‐testis antigen in multiple myeloma (MM). In this study, we determined the mechanisms regulating SPAN‐Xb expression in MM. SPAN‐Xb promoter sequence was first cloned into the CAT‐reporter vector to determine the role of promoter methylation in the regulation of gene expression. Tumor cells were treated with 5‐azacytidine and a panel of cytokines were used to determine their ability to induce SPAN‐Xb expression. Bisulfite conversion with sequence analysis was applied to a panel of tumor cells and normal tissues to correlate the CpG dinucleotide hypomethylation and SPAN‐Xb expression. We found that SPAN‐Xb promoter function could be silenced by methylation. 5‐Azacytidine induced promoter hypomethylation and resulted in SPAN‐Xb expression, at both the transcript and protein levels. Hypomethylation of the CpG dinucleotides at positions −310, −307, −299 and −221 within the SPAN‐Xb promoter strongly predict for SPAN‐Xb expression. Both IL‐7 and GM‐CSF were also able to upregulate the expression of SPAN‐Xb in myeloma cells, but only after the promoter sequence has been hypomethylated. Our results provide the first evidence showing the role of promoter methylation in the primary regulation of SPAN‐Xb and the ability of IL‐7 and GM‐CSF to further enhance SPAN‐Xb gene and protein expression in myeloma cells. © 2005 Wiley‐Liss, Inc.