Glutamine addiction and therapeutic strategies in pancreatic cancer

Pancreatic cancer remains one of the most lethal diseases worldwide owing to its late diagnosis,early metastasis,and poor prognosis.Because current therapeutic options are limited,there is an urgent need to investigate novel targeted treatment strategies.Pancreatic cancer faces significant metabolic challenges,principally hypoxia and nutrient deprivation,due to specific microenvironmental constraints,including an extensive desmoplastic stromal reaction.Pancreatic cancer cells have been shown to rewire their metabolism and energy production networks to support rapid survival and proliferation.Increased glucose uptake and glycolytic pathway activity during this process have been extensively described.However,growing evidence suggests that pancreatic cancer cells are glutamine addicted.As a nitrogen source,glutamine directly(or indirectly via glutamate conversion)contributes to many anabolic processes in pancreatic cancer,including amino acids,nucleobases,and hexosamine biosynthesis.It also plays an important role in redox homeostasis,and when converted toα-ketoglutarate,glutamine serves as an energy and anaplerotic carbon source,replenishing the tricarboxylic acid cycle intermediates.The present study aims to provide a comprehensive overview of glutamine metabolic reprogramming in pancreatic cancer,focusing on potential therapeutic approaches targeting glutamine metabolism in pancreatic cancer.

Effects of different diets on intestinal microbiota and nonalcoholic fatty liver disease development

AIM To study the effects of different diets on intestinal microbiota and nonalcoholic fatty liver disease(NAFLD) development at the same caloric intake.METHODS Thirty male Sprague-Dawley rats were randomized into five groups(six rats each). The control diet(CON) group and free high-fat diet(FFAT) group were allowed ad libitum access to a normal chow diet and a highfat diet, respectively. The restrictive high-fat diet(RFAT) group, restrictive high-sugar diet(RSUG) group, and high-protein diet(PRO) group were fed a highfat diet, a high-sugar diet, and a high-protein diet, respectively, in an isocaloric way. All rats were killed at 12 wk. Body weight, visceral fat index(visceral fat/body weight), liver index(liver/body weight), insulin resistance, portal lipopolysaccharide(LPS), serum alanine aminotransferase(ALT), serum aspartate aminotransferase(AST), and liver triglycerides were measured. The intestinal microbiota in the different groups of rats was sequenced using high-throughput sequencing technology.RESULTS The FFAT group had higher body weight, visceral fat index, liver index, peripheral insulin resistance, portal LPS, serum ALT, serum AST, and liver triglycerides compared with all other groups(P < 0.05). Taking the same calories, the RFAT and RSUG groups demonstrated increased body weight, visceral fat index, peripheral insulin resistance and liver triglycerides compared with the PRO group(P < 0.05). The RFAT group also showed increased portal LPS compared with the PRO group(P < 0.05). Unweighted Uni Frac principal coordinates analysis of the sequencing data revealed that the intestinal microbiota structures of the CON, FFAT, RSUG and PRO groups were roughly separated away from each other. Taxon-based analysis showed that, compared with the CON group, the FFAT group had an increased abundance of Firmicutes, Roseburia and Oscillospira bacteria, a higher ratio of Firmicutes to Bacteroidetes, and a decreased abundance of Bacteroidetes, Bacteroides and Parabacteroides bacteria(P < 0.05). The RFAT group showed an increased abundance of Firmicutes and decreased abundance of Parabacteroides bacteria(P < 0.05). The RSUG group showed an increased abundance of Bacteroidetes and Sutterella bacteria, higher ratio of Bacteroidetes to Firmicutes, and a decreased abundance of Firmicutes(P < 0.05). The PRO group showed an increased abundance of Bacteroidetes, Prevotella, Oscillospira and Sutterella bacteria, and a decreased abundance of Firmicutes(P < 0.05). Compared with the FFAT group, the RFAT group had an increased abundance of Bacteroidetes, higher ratio of Bacteroidetes to Firmicutes, and decreased abundance of Firmicutes and Oscillospira bacteria(P < 0.05).CONCLUSION Compared with the high-protein diet, the NAFLDinducing effects of high-fat and high-sugar diets are independent from calories, and may be associated with changed intestinal microbiota.