Metabolic consequences of LDHA inhibition by epigallocatechin gallate and oxamate in MIA PaCa-2 pancreatic cancer cells

Abstract

Lactate dehydrogenase A (LDHA) is the enzyme that converts pyruvate to lactate and oxidizes the reduced form of nicotinamide adenine dinucleotide (NADH) to NAD+. Several human cancers including the pancreas display elevated expression of LDHA. Because of its essential role in cancer metabolism, LDHA has been considered to be a potential target for cancer therapy. Recently, we have shown that a green tea extract significantly down-regulated LDHA in HPAF-II pancreatic cancer cells using global proteomics profiling. The present study is to investigate how EGCG, a major biological active constituent of green tea, targets the metabolism of human pancreatic adenocarcinoma MIA PaCa-2 cells. We compared the effect of EGCG to that of oxamate, an inhibitor of LDHA, on the multiple metabolic pathways as measured by extracellular lactate production, glucose consumption, as well as intracellular aspartate and glutamate production, fatty acid synthesis, acetyl-CoA, RNA ribose and deoxyribose. Specific metabolic pathways were studied using [1, 2-13C2]-d-glucose as the single precursor metabolic tracer. Isotope incorporations in metabolites were analyzed using gas chromatography/mass spectrometry (GC/MS) and stable isotope-based dynamic metabolic profiling (SiDMAP). We found that the EGCG treatment of MIA PaCa-2 cells significantly reduced lactate production, anaerobic glycolysis, glucose consumption and glycolytic rate that are comparable to the inhibition of LDHA by oxamate treatment. Significant changes in intracellular glucose carbon re-distribution among major glucose-utilizing macromolecule biosynthesis pathways in response to EGCG and oxamate treatment were observed. The inhibition of LDHA by EGCG or oxamate impacts on various pathways of the cellular metabolic network and significantly modifies the cancer metabolic phenotype. These results suggest that phytochemical EGCG and LDHA inhibitor oxamate confer their anti-cancer activities by disrupting the balance of flux throughout the cellular metabolic network.

Inhibition of LDHA Deliver Potential Anticancer Performance in Renal Cell Carcinoma

“…Many studies in tumors confirms the view that target LDHA may represent novel therapeutic strategies for controlling tumor growth [9,10,12,[15][16][17] . Meanwhile, previous reports showed that the expression of LDHA was abnormality abundant in RCC than that in matched normal renal tissue [2,20] , which promotes us to determine the function of LDHA on renal cancer development.…”

“…Lactate dehydrogenase A (LDHA) catalyzes the final step of glycolysis in which pyruvate is directly converted to lactate, indicating the critical role for maintaining glycolysis in tumorigenesis [14] . It has been reported that the expression of LDHA is abnormal in many human cancers, such as prostate cancer [15] , ovarian cancer [16] , pancreatic cancer [17,18] and breast cancer [19] . Meanwhile, inhibition of LDHA reduced several tumor progression [14][15][16][17] , indicating the underlying role of LDHA as a promising target for cancer therapy.…”

“…It has been reported that the expression of LDHA is abnormal in many human cancers, such as prostate cancer [15] , ovarian cancer [16] , pancreatic cancer [17,18] and breast cancer [19] . Meanwhile, inhibition of LDHA reduced several tumor progression [14][15][16][17] , indicating the underlying role of LDHA as a promising target for cancer therapy. In breast cancer, silence of LDHA suppresses tumorigenicity through induction of oxidative stress-mediated mitochondrial pathway apoptosis [19] .…”

The Warburg effect: a balance of flux analysis

“…For example, inhibition of glycogenolysis by glycogen phosphorylase inhibitor (CP-320626) resulted in significant reduction in both oxidative and non-oxidative pentose cycle activities, and decreased pyruvate dehydrogenase activity and de novo lipogenesis in pancreatic cancer MIA PaCa-2 cells apoptosis (Lee et al, 2004). Similar metabolic changes in pentose cycle and de novo lipogenesis were observed when lactic acid production was inhibited by oxamate, a lactic acid dehydrogenase (LDHA) inhibitor (Lu et al, 2014). Inhibition of signaling pathways also can impact on cancer cell metabolism and growth.…”

“…In a recent study of the effect of oxamate on the Warburg phenotype (Lu et al, 2014), it was observed that inhibition of LDHA had upstream and downstream metabolic consequences suggesting the possibility of three functional compartments, namely i) glycolytic/pentose cycle, ii) lactate/pyruvate and iii) mitochondrial/TCA compartments. These three functional compartments within the metabolic system are also suggested by the observations in the “glucose paradox” (Katz and McGarry, 1984).…”