Biochemical, Structural, and Biological Evaluation of Tranylcypromine Derivatives as Inhibitors of Histone Demethylases LSD1 and LSD2

Abstract

LSD1 and LSD2 histone demethylases are implicated in a number of physiological and pathological processes, ranging from tumorigenesis to herpes virus infection. A comprehensive structural, biochemical, and cellular study is presented here to probe the potential of these enzymes for epigenetic therapies. This approach employs tranylcypromine as a chemical scaffold for the design of novel demethylase inhibitors. This drug is a clinically validated antidepressant known to target monoamine oxidases A and B. These two flavoenzymes are structurally related to LSD1 and LSD2. Mechanistic and crystallographic studies of tranylcypromine inhibition reveal a lack of selectivity and differing covalent modifications of the FAD cofactor depending on the enantiomeric form. These findings are pharmacologically relevant, since tranylcypromine is currently administered as a racemic mixture. A large set of tranylcypromine analogues were synthesized and screened for inhibitory activities. We found that the common evolutionary origin of LSD and MAO enzymes, despite their unrelated functions and substrate specificities, is reflected in related ligand-binding properties. A few compounds with partial enzyme selectivity were identified. The biological activity of one of these new inhibitors was evaluated with a cellular model of acute promyelocytic leukemia chosen since its pathogenesis includes aberrant activities of several chromatin modifiers. Marked effects on cell differentiation and an unprecedented synergistic activity with antileukemia drugs were observed. These data demonstrate that these LSD1/2 inhibitors are of potential relevance for the treatment of promyelocytic leukemia and, more generally, as tools to alter chromatin state with promise of a block of tumor progression.

Assessment of Enzyme Inhibition: A Review with Examples from the Development of Monoamine Oxidase and Cholinesterase Inhibitory Drugs<strong> </strong>

“…Many other new series of compounds have been Cyclopropylamines Tranylcypromine (Parnate), which was introduced in the 1960s, inactivates MAO, with a slight preference for MAO B, but it inhibits MAO A in the gut sufficiently well in vivo to cause a hypertensive crisis unless dietary restrictions are followed [53]. Cyclopropylamines have been studied as inactivators of MAO [54][55][56] and of the epigentic-modifying flavoenzyme, enzyme LSD-1 [57]. Tranylcypromine ( Figure 1a) also inhibits the copper-containing amine oxidases [58] and cytochrome P450 isoforms [59,60].…”

Fluorinated tranylcypromine analogues as inhibitors of lysine-specific demethylase 1 (LSD1, KDM1A)

“…Meanwhile, as tranylcypromine itself is relatively modest in LSD1 inhibition (IC 50 ~ 25 µM), medicinal chemistry efforts have focused on second-generation analogues with higher potency. [8][9][10][11][12][13][14][15][16][17][18][19][20] Despite the mechanistic similarity between amine oxidases, the structure-activity relationships among tranylcypromine analogues is distinct for MAOs versus LSD1. For example, we found that a cyclopropylamine bearing an alkoxy substituent in lieu of the aromatic ring in 1 was a nanomolar MAO inhibitor but inactive against LSD1.…”

Novel Tranylcypromine/Hydroxylcinnamic Acid Hybrids as Lysine-Specific Demethylase 1 Inhibitors with Potent Antitumor Activity

“…2), pargyline (2), and derivatives thereof (3)(4)(5)(6), polyamines (7), peptides (8), as well as guanidine derivatives (9). 4,[15][16][17][18][19][20] Among these LSD1 inhibitors, PCPA is a classical MAO inhibitor which has been well studied, and biological studies of PCPA have uncovered the important roles of LSD1 in several cancer diseases. 21) PCPA inhibits LSD1 involving an oxidative cyclopropylamine ring-opening reaction through a single-electron transfer mechanism.…”