Epithelial-mesenchymal transition induction is associated with augmented glucose uptake and lactate production in pancreatic ductal adenocarcinoma

Abstract

BackgroundPancreatic ductal adenocarcinoma (PDAC) is a common malignancy with dismal prognosis. Metastatic spread and therapeutic resistance, the main causes of PDAC-related mortalities, are both partially underlined by the epithelial-mesenchymal transition (EMT) of PDAC cells. While the role of Warburg metabolism has been recognized in supporting rapid cellular growth and proliferation in many cancer types, less is known about the metabolic changes occurring during EMT, particularly in the context of PDAC.ResultsIn the current study, experimental models of EMT were established in the Panc-1 cell line of human PDAC via exposure to two physiologically relevant EMT inducers (tumor necrosis factor-α and transforming growth factor-β) and the metabolic consequences examined. The two EMT models displayed similar alterations in the general metabolic profile including augmented glucose uptake and lactate secretion as well as the lack of change in oxidative metabolism. Examination of molecular markers revealed differences in the pathways underlying the metabolic rewiring. 13C-Glucose tracer data confirmed that a major portion of accumulated lactate was derived from glucose, but subsequent flux analysis suggested involvement of non-canonical pathways towards lactate production.ConclusionsOur results characterize the metabolic reprogramming occurring during PDAC cell EMT and highlight the common changes of increased glucose uptake and lactate secretion under different EMT conditions. Such insight is urgently required for designing metabolic strategies to selectively target cells undergoing EMT in PDAC.Electronic supplementary materialThe online version of this article (doi:10.1186/s40170-016-0160-x) contains supplementary material, which is available to authorized users.

Normoxic cells remotely regulate the acid‐base balance of cells at the hypoxic core of connexin‐coupled tumor growths

“…1Eiii); therefore, the rate of acid injection by photolysis at the hypoxic core (J inj ) can be estimated from the product of pH i change and b i , integrated across the spheroid. J inj was thus calculated to be 20.6 6 1.2 mM/min over the 4-min uncaging protocol, which is within the range of lactic acid production rates reported in PDAC cells (6,7). Repeating this uncaging protocol in spheroids superfused with CO 2 /HCO 3 2 buffer resulted in a substantially reduced [H + ] i response (Fig.…”

“…In contrast, if lactate were catabolized or exported by an H + -independent mechanism [e.g., via connexin43 channels (23)], a greater secondary active transport flux would be necessary. J met was taken to be 15 mM/min, the midpoint of the range of lactate production rates measured in PDAC cells (6,7). To calculate J leak , passive membrane permeability to H + ions (P H ) was measured in Colo357 cells (radius 8.78 6 0.08 mm, surface area:volume ratio r = 0.342 mm 21 ) that were dissociated from monolayers and superfused with solutions that block endogenous lactic acid production (glucose replaced with galactose) and inhibit membrane pH-regulatory transport (Cl 2 replaced with gluconate, CO 2 /HCO 3 2 replaced with HEPES, and 30 mM DMA added to block Na + /H + exchange).…”

“…Pancreatic tumors in vivo receive blood-borne glucose at ;3 mmol/min per liter tumor volume (5). With ample supply of glucose, pancreatic ductal adenocarcinoma (PDAC) cells can generate 8-22 mmol lactate/min per liter of cell volume (6,7), which is enough to acidify cytoplasm by 1 pH unit in just a few minutes. In its canonical form, pH i regulation involves ATP-consuming active transport of H + (or H + -equivalent) ions across the cell membrane (8,9).…”

Unique Metabolic Adaptations Dictate Distal Organ-Specific Metastatic Colonization

“…EMT is a reversible phenomenon that allows epithelial cells to become motile and invade adjacent tissues to enter the circulation, and is an important mechanism by which carcinoma cells are thought to acquire metastatic potential (Ye and Weinberg, 2015). Moreover, a growing body of evidence has shown that the Warburg effect, a phenomenon wherein cells upregulate glycolysis while downregulating oxidative phosphorylation, is a metabolic adaptation exhibited by many cancer cells that becomes indispensible during these initial steps of metastasis (Dong et al, 2013; Liu et al, 2016). The Warburg effect allows cells to maintain ATP levels and reduce reactive oxygen species (ROS) production, allowing them to avoid anoikis, a form of cell death associated with loss of anchorage, as they enter the circulation (Kamarajugadda et al, 2012; Lu et al, 2015).…”

Lysine Restriction Affects Feed Intake and Amino Acid Metabolism via Gut Microbiome in Piglets

“…Total RNA from jejunum and ileum samples was isolated from liquid nitrogen frozen and ground tissues with TRIZOL regent (Invitrogen, USA) and then treated with DNase I (Invitrogen, USA) [21-23]. The reverse transcription was conducted at 37°C for 15 min, 95°C 5 sec.…”