Lipopolysaccharide (LPS) augment glutamine-inducedtight junction remodeling in human colorectal cancer cell

• Main Authors: Ji-Kai Chen, 陳繼開
• Other Authors: 黃菁英
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5253028%22.&searchmode=basic

碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 107 === Malignant cells exhibit metabolic alteration to adapt the harsh microenvironment, such as nutrient depletion and hypoxia. The metabolic intermediates from aerobic glycolysis (also known as Warburg effect) act as a precursor that diverted to the de novo synthesis of nucleotides, non-essential amino acids, and fatty. To compensate intermediates shortage of mitochondrial tricarboxylic acid (TCA) cycle, the process recognized as anaplerosis is used by cancer cell to replenish the metabolic intermediates of TCA to maintain cell mass and survival. Glutamine (GLN)-dependent cancer cell consume GLN as the favored anaplerotic substrate. The requirement of non-essential amino acid glutamine in cancer cells during anaplerosis has been reported, which is so-called “glutamine addiction.” Cancerous colonic cell juxtaposed to the gut microbiome-derived lipopolysaccharide (LPS) and resist to LPS-mediated cell death. Tight junctions are specialized epithelial structures for the cell-cell adhesion and interaction. Tumor dissociation and subsequent metastasis in the tumor microenvironment may occur due to the tight junction remodeling. The aim of the current study is to investigate the role of glutamine in colorectal cancer cell under LPS challenge. Caco-2 cells without or with enteral administration of 50 mM glutamine in no glucose media were exposed LPS (50-100 μg/ml). Glutamine deprivation didn’t affect TER values in Caco-2 cell in comparison to the normal group. Apical administration of glutamine in Caco-2 cells displayed a dose-dependent drop in TER at 24 hour. The reduction of TER was exacerbated after LPS exposure. However, no changes of the apical-to-basolateral dextran flux were found between control or GLN-treated cells exposed to LPS. On the other hand, immunofluorescence staining of tight junctional structure reveals lateral undulations and punctate accompanied with enlargement of cellular and nuclear size in Caco-2 cells treated with GLN. The abnormalities in tight junction structure were aggravated in cells exposed to LPS. Decrease level of ZO-1, but not claudin-1, were found in detergent-insoluble fraction of cell preparation. The decline of TER and alteration of tight junctional structure was not influencing the cell viability. Moreover, the addition of glutamate, which is the amino acid produced during the first step in glutamine catabolism, has no impact on TER. In conclusion, these results suggested that the enteral administration of glutamine, which synergy with LPS, may play a role in the modulation of tight junction dynamics through metabolism-independent pathway in colorectal cancer cells.