Chondroitin

Regulation of high molecular weight-melanoma associated antigen (HMW-MAA) gene expression by promoter DNA methylation in human melanoma cells.

Luo W, Wang X, Kageshita T, Wakasugi S, Karpf AR, Ferrone S.

Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.

The human high molecular weight-melanoma associated antigen (HMW-MAA) is a membrane-bound chondroitin sulfate proteoglycan that is variably expressed in a high percentage of melanoma cell lines and tumors. Since the mechanism(s) regulating HMW-MAA expression has(ve) not been defined, in this study, we have examined whether promoter DNA methylation regulates the level of HMW-MAA expression. In melanoma cell lines, the level of HMW-MAA mRNA and protein expression is coordinately regulated, implicating a transcriptional control mechanism. Consistent with a role for regulation by DNA methylation, we have found that a dense CpG island flanks the human HMW-MAA gene transcriptional start site. Methylation-specific PCR and sodium bisulfite DNA sequencing analyses indicate that the HMW-MAA promoter is heavily methylated in melanoma cell lines, melanoma lesions and normal lymphocytes that do not express HMW-MAA; in contrast, the HMW-MAA promoter is not methylated in melanoma cell lines and tumors that express this antigen. In addition, HMW-MAA expression is markedly induced in HMW-MAA-negative melanoma cell lines by incubation with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine. In summary, our results establish DNA methylation as a key regulator of HMW-MAA expression by human melanoma cells. This information represents a useful background to optimize immunotherapeutic strategies targeting HMW-MAA.

PMID: 16407841 [PubMed - in process]