Hypoxia is a driving force in pancreatic cancer growth and metastasis. Since the muscle isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch from aerobic to anaerobic glycolysis, we tested a series of novel Nhydroxy-2-carboxy-substituted indoles with Ki values for LDH-A reaching the low micromolar range [1]. Methods In vitro studies were performed in 14 pancreatic cancer cells lines, characterized by differential HIF-1alpha and LDH-A mRNA expression. The cytotoxic activity of the three most promising inhibitors (PI-FLY#21, 31 and 124) was evaluated with the SRB assay, whereas modulation of LDH-A mRNA, protein and activity was investigated by RT-PCR, western blot and enzymatic activity assays. Perturbation of cell cycle and apoptosis induction were studied with flow cytometry, while pharmacological interaction with gemcitabine was investigated with the combination index (CI) method. All these experiments were performed in both normoxic and hypoxic conditions (1% O2). Results LDH-A expression was detected in all the pancreatic cancer cells, and significantly increased under hypoxic conditions. The novel LDH-A inhibitors demonstrated a good antiproliferative activity, with IC50 values ranging between 9.9 and 20.3 μM in normoxic conditions, and they proved to be particularly effective under hypoxic conditions, with 100- and 2-fold reduction of IC50s in PP78 and PANC-1 cells, respectively. Furthermore, these compounds induced apoptosis, and synergistically enhanced the cytotoxic activity of gemcitabine (CI values <0.5). Conclusion These data provide evidence that LDH-A is a viable target in pancreatic cancer cells, and novel LDH-A inhibitors display synergistic cytotoxic activity with gemcitabine, offering an innovative tool for optimizing chemotherapy in hypoxic pancreatic tumors.
Synergistic Interaction of Novel Lactate Dehydrogenase Inhibitors with Gemcitabine in Hypoxic Models of Pancreatic Cancer
GRANCHI, CARLOTTA;FUNEL, NICCOLA;MACCHIA, MARCO;MINUTOLO, FILIPPO;
2011-01-01
Abstract
Hypoxia is a driving force in pancreatic cancer growth and metastasis. Since the muscle isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch from aerobic to anaerobic glycolysis, we tested a series of novel Nhydroxy-2-carboxy-substituted indoles with Ki values for LDH-A reaching the low micromolar range [1]. Methods In vitro studies were performed in 14 pancreatic cancer cells lines, characterized by differential HIF-1alpha and LDH-A mRNA expression. The cytotoxic activity of the three most promising inhibitors (PI-FLY#21, 31 and 124) was evaluated with the SRB assay, whereas modulation of LDH-A mRNA, protein and activity was investigated by RT-PCR, western blot and enzymatic activity assays. Perturbation of cell cycle and apoptosis induction were studied with flow cytometry, while pharmacological interaction with gemcitabine was investigated with the combination index (CI) method. All these experiments were performed in both normoxic and hypoxic conditions (1% O2). Results LDH-A expression was detected in all the pancreatic cancer cells, and significantly increased under hypoxic conditions. The novel LDH-A inhibitors demonstrated a good antiproliferative activity, with IC50 values ranging between 9.9 and 20.3 μM in normoxic conditions, and they proved to be particularly effective under hypoxic conditions, with 100- and 2-fold reduction of IC50s in PP78 and PANC-1 cells, respectively. Furthermore, these compounds induced apoptosis, and synergistically enhanced the cytotoxic activity of gemcitabine (CI values <0.5). Conclusion These data provide evidence that LDH-A is a viable target in pancreatic cancer cells, and novel LDH-A inhibitors display synergistic cytotoxic activity with gemcitabine, offering an innovative tool for optimizing chemotherapy in hypoxic pancreatic tumors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
