SPAN-Xb expression in myeloma cells is dependent on promoter hypomethylation and can be upregulated pharmacologically

Authors

  • Zhiqing Wang,

    1. Division of Hematology and Oncology, Texas Tech University Health Sciences Center, Amarillo, TX, USA
    2. Biotherapy and Stem Cell Transplant Program, Don and Sybil Harrington Cancer Center, Amarillo, TX, USA
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  • Jian Zhang,

    1. Division of Hematology and Oncology, Texas Tech University Health Sciences Center, Amarillo, TX, USA
    2. Biotherapy and Stem Cell Transplant Program, Don and Sybil Harrington Cancer Center, Amarillo, TX, USA
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  • Yana Zhang,

    1. Division of Hematology and Oncology, Texas Tech University Health Sciences Center, Amarillo, TX, USA
    2. Biotherapy and Stem Cell Transplant Program, Don and Sybil Harrington Cancer Center, Amarillo, TX, USA
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  • Seah H Lim

    Corresponding author
    1. Division of Hematology and Oncology, Texas Tech University Health Sciences Center, Amarillo, TX, USA
    2. Biotherapy and Stem Cell Transplant Program, Don and Sybil Harrington Cancer Center, Amarillo, TX, USA
    • Don and Sybil Harrington Cancer Center, 1500 Wallace Boulevard, Amarillo, TX 79106, USA
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    • Fax: 806-356-1928.


Abstract

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.

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