High Glucose Promotes Pancreatic Cancer Cell Glycolysis Via The Inhibition Of AMPK-dependent Autophagy

Background Pancreatic cancer(Pa C)is one of the extremely lethal diseases,which is often diagnosed at an advanced stage because of the insidious onset of the disease.Most treatments fail due to local recurrence and metastasis,which leads to an extremely poor prognosis.The bidirectional interaction between Pa C and diabetes has been confirmed by numerous studies for decades.It is suggested by recent data that T2 DM is not only a risk factor for PAC development,but also one of its manifestations.It has been recognized that diabetes plays a crucial role in the development of solid organ malignancies including liver,pancreatic,colorectal,breast,endometrial and bladder cancers.Among these cancers,pancreatic cancer(PC)shows the strongest association with T2 DM.However,the causal relationship between the two is still not completely clear,and exploring the molecular mechanisms underlying the association between T2 DM and pancreatic carcinoma is needed.Hyperglycemia is defined as a state of excessive amount of glucose circulates in the blood and DM is the most common medical condition,which causes it.Extensive epidemiological studies suggested a strong association between diabetes and Pa C,and an increase of both cancer risk and mortality in DM patients.Furthermore,there is some evidence that hyperglycemia in diabetic patients could promote tumor rogression.In addition to providing rich nutrition for tumor growth directly,hyperglycemia may also contribute to the development of Pa C by inducing the activation of some signaling pathways,all of which cooperate to a more malignant phenotype of cancer cells including proliferation,invasion,metastasis,chemotherapy resistance and chemotherapy intolerance.However,little is known about the potential mechanisms in energetic metabolism linking hyperglycemia to cancer progression and whether these mechanisms are related to the alteration of the energetic metabolism.Besides an increasing number of epidemiological investigations,there are less experimental studies investigating the molecular background between metabolic alterations and the progression of cancer.Thus,to shed light on the molecular mechanisms,more needs to be learned about which signaling pathways are involved and how they are controlled in pancreatic adenocarcinoma cells.For this purpose,we investigated the effects of increased glucose concentrations on the modulation of signaling cascades involved in cancer cell progression,with metabolomic analyses and determination of phosphorylation,expression of proteins involved in the energetic metabolism or autophagy upon hyperglycemic exposure.The study of the effects of hyperglycemia on key pathways of cancer cells such as cell proliferation,apoptosis,migration and invasion will provide us with new ways.These methods,combined with traditional chemotherapy methods,may have a strong synergistic effect on inhibiting the growth of primary tumors and metastatic lesions.It is of great significance for the treatment of pancreatic cancer and its prognosis.Objective The cancer-promoting effects of high glucose has been described in pancreatic adenocarcinoma by some signaling pathways,but the potential pathway mediating hyperglycemia-dependent promotion of pancreatic cancer cell progression in energetic metabolism remains unclear.In this study,we evaluated the relationship between metabolic changes induction by elevated glucose level and PC In vitro.Methods In the present study,we used metabolomic analyses to investigate the effects of high glucose on pancreatic cancer cells.Panc-1 cells and Bx PC-3 cells were treated with different concentrations of glucose,their protein levels of P-AMPK,LC3,HIF-1in the cytoplasm and GAPDH in the nucleus were detected by Western blot,at the same time immunohistochemical and fluorescent antibody staining techniques were used to detect HIF-1 and LC3 levels.The metabolic changes of citric acid,lactic acid and malic acid were measured.The level of intracellular ROS level was determined by using ROS assay kit.In vitro models were established to detect whether a hyperglycemia environment could cause anti-autophagy in pancreatic parenchyma and promote pancreatic cancer.Results1.Our data showed that after Panc-1 cells and Bx PC-3 cells were cultured with high glucose show elevated AMPK,Lactate,ROS and HIF-1α induced by glucose in a concentration-dependent manner.Meanwhile,the expression level of LC3,Malic acid,Citrate and GAPDH in the nucleus decreased in response to high glucose concentrations.2.Hyperglycemia inhibits phosphorylation of GAPDH and attenuates nuclear translocation of GAPDH.Decreasing GAPDH in the nucleus results in the inhibition of the deacetylation of Sirt-1,which downregulates autophagy.3.Concomitantly,inhibition of autophagy pathway leads to increase ROS,may further upregulating glycolysis.ROS promote HIF-1α,which ultimately further promotes the level of glycolysis in pancreatic cancer cells.