Targeting Glutamine Metabolism in Breast Cancer with Aminooxyacetate

Abstract

Purpose Glutamine addiction in c-MYC–overexpressing breast cancer is targeted by the aminotransferase inhibitor, aminooxyacetate (AOA). However, the mechanism of ensuing cell death remains unresolved. Experimental Design A correlation between glutamine dependence for growth and c-MYC expression was studied in breast cancer cell lines. The cytotoxic effects of AOA, its correlation with high c-MYC expression, and effects on enzymes in the glutaminolytic pathway were investigated. AOA-induced cell death was assessed by measuring changes in metabolite levels by magnetic resonance spectroscopy (MRS), the effects of amino acid depletion on nucleotide synthesis by cell-cycle and bromodeoxyuridine (BrdUrd) uptake analysis, and activation of the endoplasmic reticulum (ER) stress–mediated pathway. Antitumor effects of AOA with or without common chemotherapies were determined in breast cancer xenografts in immunodeficient mice and in a transgenic MMTV-rTtA-TetO-myc mouse mammary tumor model. Results We established a direct correlation between c-MYC overexpression, suppression of glutaminolysis, and AOA sensitivity in most breast cancer cells. MRS, cell-cycle analysis, and BrdUrd uptake measurements indicated depletion of aspartic acid and alanine leading to cell-cycle arrest at S-phase by AOA. Activation of components of the ER stress–mediated pathway, initiated through GRP78, led to apoptotic cell death. AOA inhibited growth of SUM159, SUM149, and MCF-7 xenografts and c-myc–overexpressing transgenic mouse mammary tumors. In MDA-MB-231, AOA was effective only in combination with chemotherapy. Conclusions AOA mediates its cytotoxic effects largely through the stress response pathway. The preclinical data of AOA’s effectiveness provide a strong rationale for further clinical development, particularly for c-MYC–overexpressing breast cancers.

The inhibition of c-MYC transcription factor modulates the expression of glycolytic and glutaminolytic enzymes in FaDu hypopharyngeal carcinoma cells

“…31 Thus, our results support the hypothesis that AOAA mediates cytotoxic effects through a stress response pathway. 32 Overall, the results of the study indicate that the c-MYC transcription factor, rather than HIF-1α, plays a major role in the regulation of glycolytic and glutaminolytic enzyme expression in head and neck carcinoma cells. This suggests that c-MYC inhibitors, as with 2-deoxyglucose, may show anti-proliferative activity in HNSCCs by modulating dysregulated metabolic pathways.…”

Targeting Cancer Metabolism: Dietary and Pharmacologic Interventions

“…CB-839 is under clinical investigation in several solid and hematological malignancies. Another recent paper reported GPT2 transaminase overexpression in glutamine-addicted breast cancer cell lines (160). In this study, the general TA inhibitor AOA reduced tumor cell viability, which was rescued by adding aspartate to the growth medium; this confirms glutamine contribution to neo-synthesis of other AAs (10).…”

Glutaminolysis as a target for cancer therapy

“…Aminooxyacetate, which non-specifically inhibits transaminases, has been shown to be effective in inhibiting cell proliferation and tumor growth in several preclinical studies. 89,90 …”