1,3-diketone analogs as selective lysyl hydroxylase 2 (LH2) antagonists

Lysyl hydroxylase 2 (LH2), an Fe(II) and α-ketoglutarate (αKG, also called 2-oxoglutarate, or 2OG)-dependent oxygenase, is an endoplasmic reticulum-resident enzyme that hydroxylates telopeptidyl lysine residues on fibrillar collagen molecules. It leads to the formation of hydroxylysine aldehyde-derived collagen cross-links (HLCCs), which are more stable than lysine aldehyde-derived collagen cross-links (LCCs) generated devoid of LH2. It has been reported that LH2 enhances lung cancer metastatic and invasive proclivity and modulates the types of collagen cross-links (HLCC-to-LCC) in the tumor stroma. Herein, we prepared a series of 1,3-diketone analogs 1–18 and identified 12 and 13 that inhibit the LH2-driven hydroxylation of a collagen peptide substrate with IC50 approximately 300 nM and 500 nM, respectively. 12 and 13 demonstrate a 9-fold selectivity for LH2 over LH1 and LH3. Quantum Mechanics/Molecular Mechanics (QM/MM) modeling indicates that in addition to the relatively stronger interactions between compounds 12 and 13 with the active site, the selectivity stems from non-covalent interactions like hydrogen bonding between the morpholine/piperazine rings with LH2-specific Arg661, where the corresponding residue in LH1 and LH3 is Pro. Migration assays in the 344SQ lung adenocarcinoma cell line reveal that 13 shows anti-migration activity.