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

Marina Marani,Francesca Cutruzzolà,Maurizio Gargano,Roberto Contestabile,Alessio Paone,Alessandro Paiardini,Lee Mcdermott,Alessio Fiascarelli,Serena Rinaldo,David Koes,Tianyi Yang,Alberto Macone,Giorgio Giardina,Valentino Pontecorvi

doi:10.18632/oncotarget.6726

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.

Highlights

A major feature distinguishing cancer cells from non-malignant cells is their ability to grow and divide uncontrollably
We recently demonstrated that SHMT1 plays a relevant role in lung cancer, as it is overexpressed in tissue samples from lung cancer patients and non-small-cell lung cancer (NSCLC) cell lines
The estimated inhibition constants (IC50) were: for SHMT1, 154.5 ± 14.4 μM with compound 2.2 (Supplemental Figure 1) and 57.9 ± 5.5 μM with compound 2.12 (Figure 2A); for SHMT2, 262.8 ± 48.0 μM with compound 2.2 (Supplementary Figure 1) and 227.2 ± 38.0 μM with compound 2.12 (Figure 2A)

Summary

Introduction

A major feature distinguishing cancer cells from non-malignant cells is their ability to grow and divide uncontrollably. To deal with the increasing needs caused by active proliferation, cells shift their metabolism toward aerobic glycolysis to enhance production of biosynthetic intermediates. In a subset of human tumors, including melanoma, breast and non-small-cell lung cancer (NSCLC), a significant amount of the glycolytic carbon is redirected into the synthesis of serine. Serine anabolism fuels the de novo biosynthesis of purines and pyrimidines and the production of antioxidant molecules [2,3,4]. Serine/ glycine one-carbon (SGOC) metabolism and, in particular, serine hydroxymethyltransferase (SHMT), the enzyme providing activated one-carbon units by converting serine and tetrahydrofolate (H4PteGlu) to glycine and 5, www.impactjournals.com/oncotarget

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