Structure-activity study for (bis)ureidopropyl- and (bis)thioureidopropyldiamine LSD1 inhibitors with 3-5-3 and 3-6-3 carbon backbone architectures.

Methylation at specific histone lysine residues is a critical post-translational modification that alters chromatin architecture, and dysregulated lysine methylation/demethylation is associated with the silencing of tumor suppressor genes. The enzyme lysine-specific demethylase 1 (LSD1) complexed to specific transcription factors catalyzes the oxidative demethylation of mono- and dimethyllysine 4 of histone H3 (H3K4me and H3K4me2, respectively). We have previously reported potent (bis)urea and (bis)thiourea LSD1 inhibitors that increase cellular levels of H3K4me and H3K4me2, promote the re-expression of silenced tumor suppressor genes and suppress tumor growth in vitro. Here we report the design additional (bis)urea and (bis)thiourea LSD1 inhibitors that feature 3-5-3 or 3-6-3 carbon backbone architectures. Three of these compounds displayed single-digit IC50 values in a recombinant LSD1 assay. In addition, compound 6d exhibited an IC50 of 4.2µM against the Calu-6 human lung adenocarcinoma line, and 4.8µM against the MCF7 breast tumor cell line, in an MTS cell viability assay. Following treatment with 6b-6d, Calu-6 cells exhibited a significant increase in the mRNA expression for the silenced tumor suppressor genes SFRP2, HCAD and p16, and modest increases in GATA4 message. The compounds described in this paper represent the most potent epigenetic modulators in this series, and have potential for use as antitumor agents.

Spermine oxidase mediates Helicobacter pylori-induced gastric inflammation, DNA damage, and carcinogenic signaling.

Helicobacter pylori infection is the main risk factor for the development of gastric cancer, the third leading cause of cancer death worldwide. H. pylori colonizes the human gastric mucosa and persists for decades. The inflammatory response is ineffective in clearing the infection, leading to disease progression that may result in gastric adenocarcinoma. We have shown that polyamines are regulators of the host response to H. pylori, and that spermine oxidase (SMOX), which metabolizes the polyamine spermine into spermidine plus H2O2, is associated with increased human gastric cancer risk. We now used a molecular approach to directly address the role of SMOX, and demonstrate that Smox-deficient mice exhibit significant reductions of gastric spermidine levels and H. pylori-induced inflammation. Proteomic analysis revealed that cancer was the most significantly altered functional pathway in Smox-/- gastric organoids. Moreover, there was also less DNA damage and ß-catenin activation in H. pylori-infected Smox-/- mice or gastric organoids, compared to infected wild-type animals or gastroids. The link between SMOX and ß-catenin activation was confirmed in human gastric organoids that were treated with a novel SMOX inhibitor. These findings indicate that SMOX promotes H. pylori-induced carcinogenesis by causing inflammation, DNA damage, and activation of ß-catenin signaling.

3,5-Diamino-1,2,4-triazoles as a novel scaffold for potent, reversible LSD1 (KDM1A) inhibitors.

The chromatin remodeling amine oxidase lysine-specific demethylase 1 (LSD1) has become an attractive target for the design of specific inhibitors with therapeutic potential. We, and others, have described LSD1 inhibitors that have potential as antitumor agents. Many of the currently known LSD1 inhibitors are poor drug candidates, or are structurally based on the tranylcypromine backbone, thus increasing the potential for off-target effects mediated by other amine oxidases. We now describe a series of potent LSD1 inhibitors based on a novel 1,2,4-triazole scaffold; these inhibitors show a high degree of specificity for LSD1 in vitro, and cause increases in cellular histone 3 dimethyllysine 4 (H3K4me2), a gene transcription activating mark. Importantly, these inhibitors are not toxic to mammalian cells in vitro, and thus they may show utility in the treatment of epigenetically-based diseases where cell death is not a desired endpoint Figure 1. Structures of LSD1 inhibitors 1, verlindamycin 2, (bis)thioureas 3, amidoxime 4, cyclic peptide 5, N3-(2-chloro-6-phenoxybenzyl)-4H-1,2,4-triazole-3,5-diamine 6 and N3,N5-bis(2-methoxybenzyl)-1H-1,2,4-triazole-3,5-diamine 7.