Cutaneous T-Cell Lymphoma: Yin-Yang Effects of Transcription Factors HLF and NFIL3 in Regulation of Malignant T-Cell Markers in the Context of HDAC Inhibitor Romidepsin Treatment

BACKGROUND/OBJECTIVES: We examined the in vivo effects of successive treatments with the histone deacetylase (HDAC) inhibitor romidepsin in patients with cutaneous T-cell lymphoma (CTCL), using changes in gene expression in peripheral blood mononuclear cells (PBMCs). METHODS: Exploiting data from a highly responsive CTCL patient through 12 months of treatment, we identified a malignant cell predictor (MCP), a gene signature associated with the diminishing numbers of circulating malignant cells. RESULTS: The MCP was successfully validated in the patient's relapse sample 9 months after treatment was terminated and via an independent set of CTCL patient samples. CONCLUSIONS: The MCP set of genes contained novel CTCL markers, including membrane-associated proteins not normally expressed in lymphocytes. A subclass of those markers was also detectable in residual malignant cells undetected by flow cytometry in remission samples from a patient who relapsed 10 months later. We identified a subset of transcriptional regulators, miRNAs and methylation patterns associated with the effect of progressive treatments revealing potential mechanisms of transcriptional dysregulation and functional effects in the malignant cells. We demonstrate a role for transcriptional activator HLF, over-expressed in malignant cells, and downregulated transcriptional-suppressor and immune-modulator NFIL3, as regulators of CTCL-specific genes.