A pyrazolopyran derivative preferentially inhibits the activity of human cytosolic serine hydroxymethyltransferase and induces cell death in lung cancer cells

// Marina Marani 1, * , Alessio Paone 1, * , Alessio Fiascarelli 1 , Alberto Macone 1 , Maurizio Gargano 1 , Serena Rinaldo 1 , Giorgio Giardina 1 , Valentino Pontecorvi 1 , David Koes 2 , Lee McDermott 3 , Tianyi Yang 4 , Alessandro Paiardini 5 , Roberto Contestabile 1 , Francesca Cutruzzolà 1 1 Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, Rome 00185, Italy 2 Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA 3 Department of Pharmaceutical Sciences and Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA 4 Department of Chemistry and Biochemistry Cristol 63, University of Colorado, Boulder, CO 80302, USA 5 Department of Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome, Rome 00185, Italy * These authors contributed equally to this work Correspondence to: Francesca Cutruzzolà, e-mail: francesca.cutruzzola@uniroma1.it Alessio Paone, e-mail: alessio.paone@uniroma1.it Keywords: lung cancer, serine hydroxymethyltransferase, pyrazolopyrans, inhibition, apoptosis Received: July 23, 2015 Accepted: November 25, 2015 Published: December 22, 2015 ABSTRACT Serine hydroxymethyltransferase (SHMT) is a central enzyme in the metabolic reprogramming of cancer cells, providing activated one-carbon units in the serine-glycine one-carbon metabolism. Previous studies demonstrated that the cytoplasmic isoform of SHMT (SHMT1) plays a relevant role in lung cancer. SHMT1 is overexpressed in lung cancer patients and NSCLC cell lines. Moreover, SHMT1 is required to maintain DNA integrity. Depletion in lung cancer cell lines causes cell cycle arrest and uracil accumulation and ultimately leads to apoptosis. We found that a pyrazolopyran compound, namely 2.12, preferentially inhibits SHMT1 compared to the mitochondrial counterpart SHMT2. Computational and crystallographic approaches suggest binding at the active site of SHMT1 and a competitive inhibition mechanism. A radio isotopic activity assay shows that inhibition of SHMT by 2.12 also occurs in living cells. Moreover, administration of 2.12 in A549 and H1299 lung cancer cell lines causes apoptosis at LD50 34 μM and rescue experiments underlined selectivity towards SHMT1. These data not only further highlight the relevance of the cytoplasmic isoform SHMT1 in lung cancer but, more importantly, demonstrate that, at least in vitro , it is possible to find selective inhibitors against one specific isoform of SHMT, a key target in metabolic reprogramming of many cancer types.