Synergistic interaction of novel lactate dehydrogenase inhibitors with gemcitabine against pancreatic cancer cells in hypoxia

Abstract

Background:Hypoxia is a driving force in pancreatic-ductal-adenocarcinoma (PDAC) growth, metastasis and chemoresistance. The muscle-isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch to anaerobic glycolysis, ensuring supply of energy and anabolites in hypoxic-environments. Therefore, we investigated the molecular mechanisms underlying the pharmacological interaction of novel LDH-A inhibitors in combination with gemcitabine in PDAC cells.Methods:Lactate dehydrogenase A levels were studied by quantitative RT–PCR, western blot, immunofluorescence and activity assays in 14 PDAC cells, including primary-cell-cultures and spheroids, in normoxic and hypoxic conditions. Cell proliferation, migration and key determinants of drug activity were evaluated by sulforhodamine-B-assay, wound-healing assay, PCR and LC-MS/MS.Results:Lactate dehydrogenase A was significantly increased under hypoxic conditions (1% O2), where the novel LDH-A inhibitors proved to be particularly effective (e.g., with IC50 values of 0.9 vs 16.3 μM for NHI-1 in LPC006 in hypoxia vs normoxia, respectively). These compounds induced apoptosis, affected invasiveness and spheroid-growth, reducing expression of metalloproteinases and cancer-stem-like-cells markers (CD133+). Their synergistic interaction with gemcitabine, with combination index values <0.4 in hypoxia, might also be attributed to modulation of gemcitabine metabolism, overcoming the reduced synthesis of phosphorylated metabolites.Conclusion:Lactate dehydrogenase A is a viable target in PDAC, and novel LDH-A inhibitors display synergistic cytotoxic activity with gemcitabine, offering an innovative tool in hypoxic tumours.

Galectin-4 expression is associated with reduced lymph node metastasis and modulation of Wnt/β-catenin signalling in pancreatic adenocarcinoma

“…The effects of Gal-4 on migration and invasion were evaluated as described previously [40]. Migration was investigated using the LeicaDMI300B (Leica) migration station integrated with the Scratch-Assay 6.1 software (Digital-Cell Imaging Labs, Keerbergen, Belgium).…”

Lactate dehydrogenase 5: An old friend and a new hope in the war on cancer

“…Nevertheless, some of them demonstrate high potential in combination with current therapies. It was recently showed that NHI-1 and -2 used together with gemcitabine enhanced the antiproliferative and anti-invasive activities of the chemotherapeutic drug, under both normoxia and hypoxia, in pancreatic ductal adenocarcinoma (PDAC) cell lines [85]. It was also found that NIH-2, combined with the redox-dependent bioreductive anticancer prodrug EO9, synergistically induced p53-positive cancer cell death [86].…”

When Will Small Molecule Lactate Dehydrogenase Inhibitors Realize Their Potential in the Cancer Clinic?

“…Small molecules named as NHI derivatives N-hydroxyindole derivatives endowed strong synergistic inhibitory effect on both enzyme as well as cell-based assays and also inhibited spheroid growth, cell migration and invasion in pancreatic cancer cells in combination with gemcitabine. These results offer a new hope in the development of new potent hLDH-5 inhibitors and their utilization in combination therapy for cancer treatment [12]. Very recently, the role and therapeutic potential of hLDH-5 enzyme in brain tumors has been investigated and found significant involvement of hLDH-5 in brain tumors and glioblastoma multiform.…”