To explore the proteins regulated by cyclooxygenase-2 (COX-2) in gastric cancer, the expression plasmid of COX-2siRNA was constructed and transfected into gastric cancer cell line SGC7901. Then, two-dimensional electrophoresis and the PDQuest software analysis were applied to discover the differentially expressed proteins. The differential protein spots were analyzed by matrix-assisted laser desorption/ionization time of flight mass spectrometry. Fourteen differentially expressed proteins between the two cell lines were identified. 15-Hydroxyprostaglandin dehydrogenase [NAD(+)] (15-PGDH), a key enzyme in prostaglandin degradation, was identified as an upregulated protein in SGC7901 cells transfected with the COX-2siRNA plasmid. To further explore whether the 15-PGDH is regulated by COX-2, western blotting and immunocytochemical assay were performed to detect the expression of 15-PGDH in different cell lines with different expression level of COX-2. The results showed that the expression of 15-PGDH was upregulated (128.57%) as COX-2 was suppressed by small interfering RNA and downregulated (51.72%) as COX-2 was enhanced by COX-2 cDNA transfection in gastric cancer cells. In tissue specimens with gastric cancer, there was a decreased expression of 15-PGDH and an increased expression of COX-2 simultaneously. A significantly negative correlation of 15-PGDH expression was found to COX-2 level, tumor differentiation, tumor, lymph node, metastasis (TNM) staging and lymph node metastasis of gastric cancer. All the results suggest that 15-PGDH is downregulated by COX-2 in human gastric cancer and may contribute to the carcinogenesis and development of human gastric cancer in combination with COX-2.

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome. Insulin resistance (IR) is important in the development and progression of NAFLD. Nuclear erythroid 2‑related factor 2 (Nrf2) has previously been reported to be a novel regulator in NAFLD. The present study determined that Nrf2 knockdown accelerated the onset of obesity and non‑alcoholic steatohepatitis (NASH), via the induction of hepatic IR in mice fed a high‑fat diet (HFD), which was confirmed by an increase in total and hepatic weight in Nrf2‑null‑HFD mice, in addition to marked structural disorder in liver tissues from the Nrf2‑null‑HFD group analyzed by histopathological examination. Subsequently, it was demonstrated that hepatic IR in Nrf2‑null‑HFD mice was influenced by oxidative stress; this was confirmed by an increase in malondialdehyde levels and a decrease in glutathione levels. In addition, it was determined that the induction of hepatic IR by Nrf2 knockdown in HFD-treated mice was regulated by activation of the nuclear factor‑κB (NF‑κB) signaling pathway, as detected by an increase in the expression levels of nuclear NF‑κB, and its downstream effectors interleukin‑6 and tumor necrosis factor‑α. The present study provides insight into the function of Nrf2 in NAFLD, indicating that Nrf2 deletion may lead to hepatic IR by activation of NF‑κB, which is often associated with oxidative stress. Therefore, activation of Nrf2 may limit disease progression and act as a therapeutic approach for the treatment of NASH.

Abstract. The present study aimed to investigate the protective role of curcumin against oxidative stress in rat hepatic stellate cells (HSCs)-T6, and to determine the possible underlying mechanisms. HSC-T6 cells were divided into three groups: Negative control group, oxidant-treated group and curcumin-treated group. Flow cytometry and spectrophotometry were used to measure the production of reactive oxygen species (ROS), and the levels of malondialdehyde (MDA) and glutathione (GSH). Immunocytochemistry and a radioimmunoassay were used to determine the expression of smooth muscle α-actin (α-SMA) and the secretion of extracellular matrix (ECM) molecules. In addition, western blotting and immunocytochemistry were used to determine the expression levels of nuclear factor-erythroid 2-related factor (Nrf2). Treatment with glucose oxidase (GO) significantly stimulated the formation of ROS and increased the production of MDA, as compared with the control cells; however, the production of GSH was only slightly increased. In addition, treatment with GO significantly promoted the expression of α-SMA and the secretion of ECM molecules. Conversely, treatment with curcumin significantly decreased the levels of ROS and MDA, and significantly increased the levels of GSH. Curcumin significantly inhibited the expression of α-SMA and decreased the secretion of ECM molecules. Furthermore, treatment with curcumin significantly increased the nuclear expression levels of Nrf2. These results indicated that curcumin may protect rat HSCs against oxidative stress and inhibit the GO-induced activation and secretion of ECM molecules in vitro. These effects were mediated by the upregulation of Nrf2 nuclear translocation. IntroductionPrevious studies have demonstrated that oxidative stress has a significant role in the occurrence and progression of hepatitis and hepatic fibrosis (1-4). Oxidative stress results from the excessive production of reactive oxygen species (ROS), and the inability of an organism to eliminate them. Excessive ROS lead to lipid peroxidation, protein and DNA damage, and injury to cellular structure and function (5). Numerous studies have reported the important role of ROS in various types of hepatic injury (6-10). In addition to ROS-induced inflammation, ROS may lead to loss of normal regulatory functions, resulting in tissue injury and excessive repair, and the development of hepatitis and hepatic fibrosis (11,12). It has previously been demonstrated that activation of hepatic stellate cells (HSCs) has a key role in the progression of hepatic fibrosis; therefore, HSCs are considered important target cells in hepatic fibrosis research (13). Furthermore, HSCs can be activated by oxidative stress and transformed into myofibroblasts. Myofibroblasts synthesize abundant extracellular matrix (ECM) molecules, which may lead to hepatic fibrosis (14); therefore, how to inhibit the activation of HSCs exposed to oxidative stress requires further investigation. Nuclear factor-erythroid 2-related factor (Nrf2) is a transcription fa...

Aims: Our previous work identified thioredoxin-like protein 2 (Txl-2) as the target of the monoclonal antibody MC3 associated with colon cancer, but its underlying mechanisms remain poorly understood. Txl-2, a novel thioredoxin (Trx) and nucleoside diphosphate kinase family member, is alternatively spliced and gives rise to three different Txl-2 isoforms. In this study, Txl-2 expression in colon cancer, differential functions for Txl-2 isoforms in cell invasion and metastasis, and the downstream signaling were investigated. Results: Txl-2 expression was elevated in colon cancer tissues compared to normal colonic tissues, with a high correlation between the histological grade and prognosis. Knockdown of Txl-2 expression significantly inhibited cancer cell motility, and the invasive and metastatic abilities of colon cancer cells. Interestingly, Txl-2 isoforms showed differential effects on cancer cell invasion and metastasis. Cell invasion and metastasis were significantly promoted by Txl-2b but inhibited by Txl-2c, while no obvious effect was observed for Txl-2a. Furthermore, a direct interaction was identified between Txl-2b and Ran, a Ras-related protein, by yeast two-hybrid assay and coimmunoprecipitation. PI3K pathway was found to be a major pathway mediating Txl-2b induced tumor invasion and metastasis. Innovation:The current study provides a novel biomarker and target molecule for the diagnosis and treatment of colon cancer and provides a novel paradigm to understand how alternative splicing functions in human cancer. Conclusion: Our findings demonstrate an elevated Txl-2 expression in colon cancer and that Txl-2b promotes cell invasion and metastasis through interaction with Ran and PI3K signaling pathway. Antioxid. Redox Signal. 19,[899][900][901][902][903][904][905][906][907][908][909][910][911]