Targeting Hypoxic Pancreatic Cancer Cells With Glucose Conjugated Lactate Dehydrogenase Inhibitor Nhi-Glc-2

Introduction Pancreatic ductal adenocarcinoma (PDAC) is an abysmal disease with a 5 year survival rate of merely 8%. The tumour microenvironment is one of the factors contributing to PDAC chemoresistance. More specifically, the hypoxic tumour cores and the metabolic switch to aerobic glycolysis (e.g. the Warburg effect), contribute to the lack of drug response. Interestingly, two glycolysis components glucose transporter 1 (GLUT-1) and lactate dehydrogenase A (LDH-A) are overexpressed in PDAC. The latter, LDH-A, is also correlated with prognosis in metastatic PDAC. N-Hydroxyindole-based LDH-A inhibitors (NHI-1 and NHI-2) have shown a synergistic effect in hypoxic PDAC cells when combined with gemcitabine. A glucose conjugated NHI-Glc-2 was designed to exploit the GLUT-1 overexpression in PDAC cells and in the present study we evaluated whether this novel compound further improved the pharmacological effect of LDH-A inhibitors. Material and methods The effect of NHI-Glc-2 on cell growth is tested in our primary PDAC cancer cell cultures, characterised for their hypoxic signature and LDH-A/GLUT-1 expression levels by next-generation sequencing. Inhibition of cell and tumour growth was evaluated by the SRB assay, 3D spheroid-cultures and with an orthotopic bioluminescent in vivo model. Additionally, LDH-A enzyme activity inhibition and the effect on the glycolytic rate by NHI-Glc-2 were assessed by spectrophotometry and with the Seahorse XF analyzer, respectively. Results and discussions NHI-Glc-2 is capable of inhibiting PDAC cell growth in, especially in hypoxia, in nanomolar range and shows a synergistic effect with gemcitabine. In 3D cultures NHI-Glc-2 disrupts spheroid integrity, and preliminary in vivo studies show promising results. Conclusion Lactate dehydrogenase A is a viable target in PDAC, and the novel LDH-A inhibitor showed improved pharmacological effect in normoxic and hypoxic PDAC cells compared to NHI-1 and NHI-2. Moreover, this compound displays a synergistic cytotoxic activity with gemcitabine, offering an innovative tool in hypoxic tumours.