TY - JOUR T1 - Cellular pharmacodynamics of a novel pyrrolo[3,2-d]pyrimidine inhibitor targeting mitochondrial and cytosolic one-carbon metabolism JF - Molecular Pharmacology JO - Mol Pharmacol DO - 10.1124/mol.119.117937 SP - mol.119.117937 AU - Aamod S. Dekhne AU - Chengwen Ning AU - Md. Junayed Nayeen AU - Khushbu Shah AU - Hasini Kalpage AU - Josphephine Fruhauf AU - Adrianne Wallace-Povirk AU - Carrie O'Connor AU - Zhanjun Hou AU - Seongho Kim AU - Maik Huttemann AU - Aleem Gangjee AU - Larry H. Matherly Y1 - 2019/01/01 UR - http://molpharm.aspetjournals.org/content/early/2019/11/09/mol.119.117937.abstract N2 - Folate-dependent one-carbon (C1) metabolism is compartmentalized in the mitochondria and cytosol and is a source of critical metabolites for proliferating tumors. Mitochondrial C1 metabolism including serine hydroxymethyltransferase 2 (SHMT2) generates glycine for de novo purine nucleotide and glutathione biosynthesis, and is an important source of NADPH, ATP, and formate, which affords C1 units as 10-formyl-tetrahydrofolate and 5,10-methylene-tetrahydrofolate for nucleotide biosynthesis in the cytosol. We previously discovered novel first-in-class multi-targeted pyrrolo[3,2-d]pyrimidine inhibitors of SHMT2 and de novo purine biosynthesis at glycinamide ribonucleotide formyltransferase and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase with potent in vitro and in vivo antitumor efficacy toward pancreatic adenocarcinoma cells. In this report, we extend our findings to an expanded panel of pancreatic cancer models. We used our lead analog AGF347 to characterize pharmacodynamic determinants of antitumor efficacy for this series and demonstrated plasma membrane transport into the cytosol, uptake from cytosol into mitochondria, and metabolism to AGF347 polyglutamates in both cytosol and mitochondria. Antitumor effects of AGF347 downstream of SHMT2 and purine biosynthesis included suppression of mTOR signaling, and glutathione depletion with increased levels of reactive oxygen species. Our results provide important insights into the cellular pharmacology of novel pyrrolo[3,2-d]pyrimidine inhibitors as antitumor compounds and establish AGF347 as a unique agent for potential clinical application for pancreatic cancer, as well as other malignancies.SIGNIFICANCE STATEMENT This study establishes the antitumor efficacies of novel inhibitors of serine hydroxymethyltransferase (SHMT) 2 and of cytosolic targets toward a panel of clinically relevant pancreatic cancer cells and demonstrates the important roles of plasma membrane transport, mitochondrial accumulation, and metabolism to polyglutamates of the compound lead AG347 to drug activity. We also establish that loss of serine catabolism and purine biosynthesis resulting from AGF347 treatment impacts mTOR signaling, glutathione pools and reactive oxygen species, contributing to antitumor efficacy. ER -