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).

Methods: Laboratory investigation. Methods: Dermatology research unit of a university medical center. Methods: Five CTCL lines and Sézary syndrome blood. Methods: Treatment of cells with 5-azacytidine (aza), methotrexate, and interferon alfa-2b. Methods: 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.