Cetuximab Reverses the Warburg Effect by Inhibiting HIF-1–Regulated LDH-A

Abstract

Hypoxia-inducible factor-1 (HIF-1) plays a critical role in reprogramming cancer metabolism towards aerobic glycolysis (i.e., the Warburg effect), which is critical to supplying cancer cells with the biomass needed for proliferation. Previous studies have shown that cetuximab, an epidermal growth factor receptor-blocking monoclonal antibody, downregulates the alpha subunit of HIF-1 (HIF-1α) through the inhibition of epidermal growth factor receptor downstream cell signaling and that downregulation of HIF-1α is required for cetuximab-induced antiproliferative effects. However, the mechanism underlying these actions has yet to be identified. In this study, we used the Seahorse XF96 extracellular flux analyzer to assess the effect of cetuximab treatment on changes in glycolysis and mitochondrial respiration, the two major energy-producing pathways, in live cells. We found that cetuximab downregulated lactate dehydrogenase A (LDH-A) and inhibited glycolysis in cetuximab-sensitive head and neck squamous cell carcinoma (HNSCC) cells in a HIF-1α downregulation–dependent manner. HNSCC cells with acquired cetuximab resistance expressed a high level of HIF-1α and were highly glycolytic. Overexpression of a HIF-1α mutant (HIF-1α/ΔODD) conferred resistance to cetuximab-induced G1-phase cell cycle arrest, which could be overcome by knockdown of LDH-A expression. Inhibition of LDH-A activity with oxamate enhanced the response of cetuximab-resistant cells to cetuximab. Cetuximab had no noticeable inhibitory effect on glycolysis in nontransformed cells. These findings provide novel mechanistic insights into cetuximab-induced cell cycle arrest from the perspective of cancer metabolism and suggest novel strategies for enhancing cetuximab response.

Extracellular Lumican Inhibits Pancreatic Cancer Cell Growth and Is Associated with Prolonged Survival after Surgery

“…Glucose, lactate production, and intracellular ATP were measured using glucose and lactate assay kits and an ATP bioluminescent assay according to the manufacturers’ instructions and a previous report (26). …”

“…Previous work has demonstrated that HIF-1α lies downstream of epidermal growth factor receptor (EGFR), and anti-EGFR treatment using cetuximab (an EGFR-blocking monoclonal antibody) can downregulate HIF-1α protein by inhibiting the PI3K/Akt and MEK/Erk pathways. In fact, downregulation of HIF-1α is required for cetuximab to inhibit cell glycolysis and induce cell apoptosis (25, 26). …”

MicroRNA-124 suppresses proliferation and glycolysis in non–small cell lung cancer cells by targeting AKT–GLUT1/HKII

“…4,5 The AKT pathway and hypoxiainducible factor 1 (HIF-1) are major signaling cascade that regulates glucose metabolism as well as controls cellular growth. 6,7 They could enhance glucose transporter gene expression, increase phosphofructokinase activity, and stimulate the glucose to lactate metabolic pathway, 8,9 AKT mainly enhances hexokinase II (HKII) gene expression, thus promoting glucose capture. 10 MicroRNAs (miRNAs) are single-stranded, small noncoding RNAs with 18-25 nucleotides in length.…”

Early drop in serum lactate dehydrogenase concentrations as a predictor of tumor response to ongoing anti-epidermal growth factor receptor antibody treatment

“…In tumor cells, LDH-5, which is regulated by hypoxia-inducible factors (HIF), plays a key role in anaerobic glycolysis. One study revealed that cetuximab downregulates HIF-1α protein by inhibiting the phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (Erk) pathways 7) . Consequently, the expression of LDH-5 can be reduced by cetuximab treatment.…”