The discovery of a non-competitive GOT1 inhibitor, hydralazine hydrochloride, via a coupling reaction-based high-throughput screening assay

Glutamate oxaloacetate transaminase 1 (GOT1) plays a key role in aberrant glutamine metabolism. GOT1 suppression can arrest tumor growth and prevent the development of cancer, indicating GOT1 as a potential anticancer target. Reported GOT1 inhibitors, on the other hand, are quite restricted. Here, we developed and optimized a coupling reaction-based high-throughput screening assay for the discovery of GOT1 inhibitors. By using this screening assay, we found that the cardiovascular drug hydralazine hydrochloride inhibited GOT1 catalytic activity, with an IC₅₀ of 26.62 ± 7.45 μM, in a non-competitive and partial-reversible manner. In addition, we determined the binding affinity of hydralazine hydrochloride to GOT1, with a K_d of 16.54 ± 8.59 μM, using a microscale thermophoresis assay. According to structure-activity relationship analysis, the inhibitory activity of hydralazine hydrochloride is mainly derived from its hydrazine group. Furthermore, it inhibits the proliferation of cancer cells MCF-7 and MDA-MB-468 with a slight inhibitory effect compared to other tested cancer cells, highlighting GOT1 as a promising therapeutic target for the treatment of breast cancer.

A novel circular RNA hsa_circRNA_103809/miR-377-3p/GOT1 pathway regulates cisplatin-resistance in non-small cell lung cancer (NSCLC)

Background

Cisplatin is the first-line chemotherapeutic drug for non-small cell lung cancer (NSCLC), and emerging evidences suggests that targeting circular RNAs (circRNAs) is an effective strategy to increase cisplatin-sensitivity in NSCLC, but the detailed mechanisms are still not fully delineated.

Methods

Cell proliferation, viability and apoptosis were examined by using the cell counting kit-8 (CCK-8) assay, trypan blue staining assay and Annexin V-FITC/PI double staining assay, respectively. The expression levels of cancer associated genes were measured by using the Real-Time qPCR and Western Blot analysis at transcriptional and translated levels. Dual-luciferase reporter gene system assay was conducted to validated the targeting sites among hsa_circRNA_103809, miR-377-3p and 3′ untranslated region (3’UTR) of GOT1 mRNA. The expression status, including expression levels and localization, were determined by immunohistochemistry (IHC) assay in mice tumor tissues.

Results

Here we identified a novel hsa_circRNA_103809/miR-377-3p/GOT1 signaling cascade which contributes to cisplatin-resistance in NSCLC in vitro and in vivo. Mechanistically, parental cisplatin-sensitive NSCLC (CS-NSCLC) cells were subjected to continuous low-dose cisplatin treatment to generate cisplatin-resistant NSCLC (CR-NSCLC) cells, and we found that hsa_circRNA_103809 and GOT1 were upregulated, while miR-377-3p was downregulated in CR-NSCLC cells but not in CS-NSCLC cells. In addition, hsa_circRNA_103809 sponged miR-337-3p to upregulate GOT1 in CS-NSCLC cells, and knock-down of hsa_circRNA_103809 enhanced the inhibiting effects of cisplatin on cell proliferation and viability, and induced cell apoptosis in CR-NSCLC cells, which were reversed by downregulating miR-377-3p and overexpressing GOT1. Consistently, overexpression of hsa_circRNA_103809 increased cisplatin-resistance in CS-NSCLC cells by regulating the miR-377-3p/GOT1 axis. Finally, silencing of hsa_circRNA_103809 aggravated the inhibiting effects of cisplatin treatment on NSCLC cell growth in vivo.

Conclusions

Analysis of data suggested that targeting the hsa_circRNA_103809/miR-377-3p/GOT1 pathway increased susceptibility of CR-NSCLC cells to cisplatin, and this study provided novel targets to improve the therapeutic efficacy of cisplatin for NSCLC treatment in clinic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07680-w.

Inhibition of glutamate oxaloacetate transaminase 1 in cancer cell lines results in altered metabolism with increased dependency of glucose

BACKGROUND

Glutamate oxaloacetate transaminase 1 (GOT1) regulates cellular metabolism through coordinating the utilization of carbohydrates and amino acids to meet nutrient requirements. KRAS mutated cancer cells were recently shown to rely on GOT1 to support long-term cell proliferation. The aim of the present study was to address the role of GOT1 in the metabolic adaption of cancer cells.

METHODS

GOT1-null and knockdown cell lines were established through CRISPR/Cas9 and shRNA techniques. The growth properties, colony formation ability, autophagy and selected gene expression profiles were analysed. Glucose deprivation decreased the viability of the GOT1-null cells and rescue experiments were conducted with selected intermediates. The redox NADH/NAD⁺ homeostasis as well as lactate secretion were determined. GOT1 expression levels and correlation with survival rates were analysed in selected tumor databases.

RESULTS

Inhibition of GOT1 sensitized the cancer cells to glucose deprivation, which was partially counteracted by oxaloacetate and phosphoenol pyruvate, metabolic intermediates downstream of GOT1. Moreover, GOT1-null cells accumulated NADH and displayed a decreased ratio of NADH/NAD⁺ with nutrient depletion. The relevance of GOT1 as a potential target in cancer therapy was supported by a lung adenocarcinoma RNA-seq data set as well as the GEO:GSE database of metastatic melanoma where GOT1 expression was increased. High levels of GOT1 were further linked to poor survival as analysed by the GEPIA web tool, in thyroid and breast carcinoma and in lung adenocarcinoma.

CONCLUSIONS

Our study suggests an important role of GOT1 to coordinate the glycolytic and the oxidative phosphorylation pathways in KRAS mutated cancer cells. GOT1 is crucial to provide oxaloacetate at low glucose levels, likely to maintain the redox homeostasis. Our data suggest GOT1 as a possible target in cancer therapy.