Identification and characterization of a novel SNAT2 (SLC38A2) inhibitor reveals synergy with glucose transport inhibition in cancer cells

Abstract

SNAT2 (SLC38A2) is a sodium-dependent neutral amino acid transporter, which is important for the accumulation of amino acids as nutrients, the maintenance of cellular osmolarity, and the activation of mTORC1. It also provides net glutamine for glutaminolysis and consequently presents as a potential target to treat cancer. A high-throughput screening assay was developed to identify new inhibitors of SNAT2 making use of the inducible nature of SNAT2 and its electrogenic mechanism. Using an optimized FLIPR membrane potential (FMP) assay, a curated scaffold library of 33934 compounds was screened to identify 3-(N-methyl (4-methylphenyl)sulfonamido)-N-(2-trifluoromethylbenzyl)thiophene-2-carboxamide as a potent inhibitor of SNAT2. In two different assays an IC50 of 0.8–3 µM was determined. The compound discriminated against the close transporter homologue SNAT1. MDA-MB-231 breast cancer and HPAFII pancreatic cancer cell lines tolerated the SNAT2 inhibitor up to a concentration of 100 µM but in combination with tolerable doses of the glucose transport inhibitor Bay-876, proliferative growth of both cell lines was halted. This points to synergy between inhibition of glycolysis and glutaminolysis in cancer cells.

Dual Starvations Induce Pyroptosis for Orthotopic Pancreatic Cancer Therapy through Simultaneous Deprivation of Glucose and Glutamine

“…The previous reports demonstrated that inhibition of glucose uptake has a synergistic effect with the inhibition of glutamine uptake in pancreatic cancer cells. 20 However, it may not exhibit significant abnormality when the glucose uptake pathway is activated, and glutamine uptake compensates for energy when glucose uptake is inhibited. Therefore, we additionally estimated the correlation of GLUT1 with glutamine transporters and found that ASCT2 was significantly correlated with GLUT1 (Pearson correlation, P = 5.68 × 10 −12 , r = 0.48, Figure 1G).…”

Exploring Amino Acid Transporters as Therapeutic Targets for Cancer: An Examination of Inhibitor Structures, Selectivity Issues, and Discovery Approaches

“…Of course, this approach requires a large library of chemically diverse compounds as well as a scalable assay that can screen many compounds at a time. An example of this approach has recently been used to discover inhibitors of SNAT2 by screening a library of 33,934 compounds [ 32 ]. However, a more focused screen can be implemented if resources are limited or if only low-throughput assays are available.…”

“…Here, it was shown that SNAT1 was inhibited by GPNA, GHX, and BS, whereas only GPNA and BS could significantly inhibit SNAT2 [ 22 ]. Later, it was shown that GHX inhibits SNAT2 with an IC 50 of 0.33 mM [ 32 ]. However, these compounds could also inhibit ASCT2, SNAT4, and SNAT5, highlighting their lack of specificity [ 22 ].…”

“…Recently, a high-throughput screen of 33,934 compounds was used to find the potent inhibitor of SNAT2, 3-(N-methyl (4-methylphenyl)sulfonamido)-N-(2-trifluoromethylbenzyl)thiophene-2-carboxamide (MMTC, Figure 5 ). MMTC inhibited Pro uptake in amino acid-starved SKOV3 ovarian cancer cells with an IC 50 of 0.8 µM [ 32 ]. The inhibitor appeared to be selective for SNAT2 over SNAT1 but did not appear to inhibit the growth of pancreatic, breast, and ovarian cancer cell lines within its solubility range.…”

Metabolism in Cancer Stem Cells: Targets for Clinical Treatment

“…Glucose metabolism is the first and most widely studied metabolic abnormality in cancer cells ( Figure 1 ) [ 21 , 22 , 23 , 24 ]. Normal cells metabolize glucose into carbon dioxide and water through oxygen-consuming mitochondrial metabolism in physiological conditions, but convert glucose into lactic acid (glycolysis) in a low oxygen and anaerobic environment [ 25 ].…”