Effects of 6-Aminonicotinic Acid Esters on the Reprogrammed Epigenetic State of Distant Metastatic Pancreatic Carcinoma
Run-Duo Gao, Masahiro Maeda, Carolyn Tallon, Andrew P. Feinberg, Barbara S. Slusher, Takashi Tsukamoto
Abstract
In the search for alternatives to 6-aminonicotinamide (6AN), a series of 6-aminonicotinic acid esters were designed and synthesized as precursors of 6-amino-NADP+, a potent inhibitor of 6-phosphogluconate dehydrogenase (6PGD). Like 6AN, some of these esters were found to reverse the loss of histone 3 lysine 9 trimethylation (H3K9me3) in patient-derived pancreatic ductal adenocarcinoma (PDAC) distant metastasis (A38-5). Among them, 1-(((cyclohexyloxy)carbonyl)oxy)ethyl 6-aminonicotinate (5i) showed more potent antiproliferative activity than 6AN. Metabolite analysis revealed that compound 5i produced a marked increase in metabolites upstream of 6PGD, indicating intracellular inhibition of 6PGD by 6-amino-NADP+ derived from compound 5i through 6-aminonicotinic acid (6ANA) via the Preiss–Handler pathway. Despite the more potent pharmacological effects shown by compound 5i in A38-5, compound 5i was found to be substantially less toxic to primary hippocampal rat neurons compared to 6AN, indicating its therapeutic potential in targeting distant metastatic cells.