NF-κB-dependent and -independent epigenetic modulation using the novel anti-cancer agent DMAPT

Abstract

The transcription factor nuclear factor-kappaB (NF-κB) is constitutively active in several cancers and is a target of therapeutic development. We recently developed dimethylaminoparthenolide (DMAPT), a clinical grade water-soluble analog of parthenolide, as a potent inhibitor of NF-κB and demonstrated in vitro and in vivo anti-tumor activities in multiple cancers. In this study, we show DMAPT is an epigenetic modulator functioning in an NF-κB-dependent and -independent manner. DMAPT-mediated NF-κB inhibition resulted in elevated histone H3K36 trimethylation (H3K36me3), which could be recapitulated through genetic ablation of the p65 subunit of NF-κB or inhibitor-of-kappaB alpha super-repressor overexpression. DMAPT treatment and p65 ablation increased the levels of H3K36 trimethylases NSD1 (KMT3B) and SETD2 (KMT3A), suggesting that NF-κB directly represses their expression and that lower H3K36me3 is an epigenetic marker of constitutive NF-κB activity. Overexpression of a constitutively active p65 subunit of NF-κB reduced NSD1 and H3K36me3 levels. NSD1 is essential for DMAPT-induced expression of pro-apoptotic BIM, indicating a functional link between epigenetic modification and gene expression. Interestingly, we observed enhanced H4K20 trimethylation and induction of H4K20 trimethylase KMT5C in DMAPT-treated cells independent of NF-κB inhibition. These results add KMT5C to the list NF-κB-independent epigenetic targets of parthenolide, which include previously described histone deacetylase 1 (HDAC-1) and DNA methyltransferase 1. As NSD1 and SETD2 are known tumor suppressors and loss of H4K20 trimethylation is an early event in cancer progression, which contributes to genomic instability, we propose DMAPT as a potent pharmacologic agent that can reverse NF-κB-dependent and -independent cancer-specific epigenetic abnormalities.

Pharmacological Dual Inhibition of Tumor and Tumor-Induced Functional Limitations in a Transgenic Model of Breast Cancer

“…DMAPT is a water-soluble analogue of parthenolide, an active ingredient of the herb feverfew (22,27). As with many targeted therapies, DMAPT displays NF-κB-dependent and NF-κB-independent activities; however, its major therapeutic effects are likely through NF-κB inhibition (22).…”

“…DMAPT is a water-soluble analogue of parthenolide, an active ingredient of the herb feverfew (22,27). As with many targeted therapies, DMAPT displays NF-κB-dependent and NF-κB-independent activities; however, its major therapeutic effects are likely through NF-κB inhibition (22). Treatment with DMAPT (100mg/kg, 5 times/week, orally), starting at 6-8 weeks of age, prior to visual appearance of mammary tumors, delayed mammary tumor visual onset and slowed tumor growth rates compared to vehicle treatment (Supplementary Table S1).…”

“…Genome-wide comparative analyses of multiple transgenic mammary tumor models have suggested PyMT + model to represent the luminal B intrinsic subtype of breast cancer (21). We used dimethylaminoparthenolide (DMAPT), a water-soluble analogue of parthenolide, which we have previously shown to have potent NF-κB inhibitory activity (22) and has been shown to overcome the adverse effects of persistent activation of NF-κB in BRCA1-deficient mammary luminal progenitor cells in vivo (23). We found that mammary tumor development in PyMT + mice was accompanied with functional limitations such as reduced grip strength, impaired rotarod balance, causing altered body composition as well as molecular changes in muscle including reduced expression of miR-486 and MyoD as we reported previously (14).…”

H3K36 Methyltransferases as Cancer Drug Targets: Rationale and Perspectives for Inhibitor Development

“…In bladder cancer cells, for example, inhibition of NF-κB by small molecule causes NSD1-dependent activation of proapoptotic BIM and the cell cycle regulator p21 [52]. Although it is not known if NSD1 KMTase activity is involved here, NF-κB inhibition does increase global levels of H3K36 trimethylation in addition to NSD1 expression [52].…”

“…In bladder cancer cells, for example, inhibition of NF-κB by small molecule causes NSD1-dependent activation of proapoptotic BIM and the cell cycle regulator p21 [52]. Although it is not known if NSD1 KMTase activity is involved here, NF-κB inhibition does increase global levels of H3K36 trimethylation in addition to NSD1 expression [52]. Moreover, NSD1 frequently undergoes inactivating mutations causing premature termination of the protein in head and neck squamous cell carcinoma [53], and NSD1 is epigenetically silenced in neuroblastoma and glioma [54].…”