Mechanism consequences and therapeutic targeting of abnormal IL-15 signaling in cutaneous T-cell lymphoma

摘要

Cutaneous T-cell lymphoma (CTCL) is the most common type of primary cutaneous lymphoma. Here we report that CTCL patients show increased interleukin-15 (IL-15) in a clinical stage-dependent manner. Mechanistically, we show that Zeb1 is a transcriptional repressor of IL-15 in T-cells and that hypermethylation of the Zeb1 binding region within the IL-15 promoter, as seen in CTCL patients, prevents Zeb1 binding and causes increased transcription of IL-15. Using a transgenic mouse model of IL-15, we provide evidence that overexpression of IL-15 induces a spontaneous CTCL that mimics the human neoplasm. Excessive autocrine production of IL-15 in T-cells inhibits an HDAC1-mediated negative autoregulatory loop, resulting in the upregulation of HDAC1 and HDAC6, and transcriptional induction of the onco-miR-21. Interruption of IL-15 downstream signaling with isotype-specific HDAC inhibitors halts (HDAC1) or significantly delays (HDAC6) the progression of CTCL in vivo and provides pre-clinical evidence supporting a hierarchical model of oncogenic signaling in CTCL.