Reduction of Fas/CD95 promoter methylation, upregulation of Fas protein, and enhancement of sensitivity to apoptosis in cutaneous T-cell lymphoma.

OBJECTIVE

To explore the relationships among (Fas) promoter methylation, Fas expression, and apoptotic sensitivity in cutaneous T-cell lymphoma (CTCL).

DESIGN

Laboratory investigation.

SETTING

Dermatology research unit of a university medical center.

SAMPLES

Five CTCL lines and Sézary syndrome blood.

INTERVENTIONS

Treatment of cells with 5-azacytidine (aza), methotrexate, and interferon alfa-2b.

MAIN OUTCOME MEASURES

Fas promoter methylation, Fas expression, and sensitivity to Fas-mediated apoptosis.

RESULTS

Fas promoter methylation correlates inversely with the level of Fas transcript, protein, and apoptotic sensitivity in CTCL. Increased DNA methylation also correlates with decreased NFkB (nuclear factor kappa-light chain enhancer of activated B cells) binding to the Fas promoter. All of these relationships were reversed by the DNA-demethylating agent, 5-aza. We found that methotrexate also functions as a DNA-demethylating agent by depleting methyl donors and, together with interferon alfa-2b, upregulates Fas and enhances sensitivity to Fas-mediated apoptosis.

CONCLUSIONS

These findings help explain the previously reported impressive responses of patients with advanced CTCL to combination therapy with methotrexate and interferon alfa. They also provide a new rationale for the treatment of CTCL with methotrexate and its use in combination with other agents.