Benzylserine inhibits breast cancer cell growth by disrupting intracellular amino acid homeostasis and triggering amino acid response pathways

Abstract

BackgroundCancer cells require increased levels of nutrients such as amino acids to sustain their rapid growth. In particular, leucine and glutamine have been shown to be important for growth and proliferation of some breast cancers, and therefore targeting the primary cell-surface transporters that mediate their uptake, L-type amino acid transporter 1 (LAT1) and alanine, serine, cysteine-preferring transporter 2 (ASCT2), is a potential therapeutic strategy.MethodsThe ASCT2 inhibitor, benzylserine (BenSer), is also able to block LAT1 activity, thus inhibiting both leucine and glutamine uptake. We therefore aimed to investigate the effects of BenSer in breast cancer cell lines to determine whether combined LAT1 and ASCT2 inhibition could inhibit cell growth and proliferation.ResultsBenSer treatment significantly inhibited both leucine and glutamine uptake in MCF-7, HCC1806 and MDA-MB-231 breast cancer cells, causing decreased cell viability and cell cycle progression. These effects were not primarily leucine-mediated, as BenSer was more cytostatic than the LAT family inhibitor, BCH. Oocyte uptake assays with ectopically expressed amino acid transporters identified four additional targets of BenSer, and gas chromatography-mass spectrometry (GCMS) analysis of intracellular amino acid concentrations revealed that this BenSer-mediated inhibition of amino acid uptake was sufficient to disrupt multiple pathways of amino acid metabolism, causing reduced lactate production and activation of an amino acid response (AAR) through activating transcription factor 4 (ATF4).ConclusionsTogether these data showed that BenSer blockade inhibited breast cancer cell growth and viability through disruption of intracellular amino acid homeostasis and inhibition of downstream metabolic and growth pathways.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-4599-8) contains supplementary material, which is available to authorized users.

Ablation of the ASCT2 (SLC1A5) gene encoding a neutral amino acid transporter reveals transporter plasticity and redundancy in cancer cells

“…LAT1 transports most essential amino acids, and the resilience against JPH203 in 143B ASCT2ko cells may be caused by up-regulation of LAT2 or nutrient import via macropinocytosis (31). Neither ASCT2wt cell line was sensitive to JPH203 alone, confirming previous data for HCC1806 cells (18) and refuting the notion that LAT1 is essential for signaling to mTORC1 (7). The combination of ASCT2ko, inhibition of GCN2, and silencing of SNAT1 com- Figure 6.…”

HIFs, angiogenesis, and metabolism: elusive enemies in breast cancer

“…Dependence of breast cancer cells on glutamine is increased not only in hypoxia but also in estrogen-independent and anti-estrogen treatment-resistant subtypes (151). Preclinically, pharmacological targeting of HIF-regulated amino acid importers, for instance by the SLC1A5 inhibitors benzylserine or V-9302, blocks breast cancer cell growth and is associated with decreased mTOR signaling and increased ROS levels and autophagy (69,71,152,153).…”

Oncology Therapeutics Targeting the Metabolism of Amino Acids

“…The V-9302 treatment attenuates cancer cell growth both in vitro and in vivo, implying potential therapeutic benefits of V-9302 for cancer patients with high ASCT2 [20]. Benzylserine and benzylcysteine are competitive inhibitors of ASCT2 [21] and have been reported to suppress cancer cell growth (benzylserine in breast cancer cells and benzylcysteine in gastric cancer cells, respectively) [22,23]. L-γ-Glutamyl-p-nitroanilide (GPNA) also targets ASCT2.…”

“…While promising, the described ASCT2 inhibitors need additional optimization to enable future development. Dose regimens need further evaluation for benzylserine and benzylcysteine, as millimolar concentrations are required to block cancer cell growth even in vitro [22]. Since Na + -dependent AATs are not limited to ASCT2, GPNA can inhibit other transporters such as L-type amino acid transporter 1 (LAT1, encoded by SLC7A5) and System A transporters SNAT1 (encoded by SLC38A1) and SNAT2 (encoded by SLC38A2).…”