Epidermal growth factor (EGF) signaling has been shown to induce epithelial to mesenchymal transition (EMT) in many types of cancer cells. However, the molecular mechanism of EGF-induced EMT in gastric cancer remains largely unknown. In the present study, we found that human gastric cancer cell lines SGC-7901 and BGC-823 underwent EMT phenotypic changes upon exposure to EGF. The induction of EMT was consistent with aggressive characteristics such as increased cell migration, invasion and clonogenic growth. Additionally, EGF stimulation also led to the upregulation of urokinase plasminogen activator receptor (uPAR) both at mRNA and protein levels. Knockdown of uPAR by siRNA significantly attenuated EMT induction by EGF in SGC-7901 and BGC-823 cells. Furthermore, EGF increased ERK1/2 activity and blocking ERK1/2 signaling with its inhibitor, U0126, markedly inhibited EGF-induced uPAR expression and consequently EMT. Collectively, the present study demonstrated that EGF induced aggressiveness of gastric cancer cells by activating EMT, which involved the activation of the ERK1/2 pathway and, subsequently, uPAR expression.
In this work, in order to find a method for the accurate determination of chemical oxygen demand (COD Cr) in high chloride oilfield wastewater, the interferences of chloridion (Cl −) on COD Cr determination were first studied based on the Chinese national standard GB 11914-89. The results showed that the COD Cr values and deviations determined by the classical potassium dichromate (K 2 Cr 2 O 7) method increased gradually with the increase of Cl − mass concentration in water samples. Then, theoretical and experimental studies on reducing interferences of Cl − on COD Cr determination were carried out. The results showed that different concentrations of K 2 Cr 2 O 7 exhibited different oxidation capacities on Cl − , while having little effects on the oxidation of organic compounds. More specifically, when the concentration of K 2 Cr 2 O 7 was 0.025 mol•L −1 and the mass ratio of HgSO 4 :Cl − was 10:1, the interferences of Cl − on COD Cr determination were the slightest. Finally, a low concentration oxidant method was proposed for the accurate determination of COD Cr in high chloride oilfield wastewaters. The performances of the proposed method were verified by the simulated and actual high chloride oilfield wastewater. The results showed that when Cl − ≤ 20,000 mg•L −1 and COD < 100 mg•L −1 , the relative prediction errors of COD Cr provided by the proposed method were acceptable, which revealed that the low concentration oxidant method is feasible and reliable for the determination of COD Cr in high chloride oilfield wastewater.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.