| Objective Extracellular signal-regulated kinase (ERK1/2), which involved in regulating cell survival, proliferation, differentiation and tissue invasion through the cascade of phosphorylation and responses to tumor occurrence, development metastasis, is an important target in cancer treatment. Permanent implantation of125|seeds brachytherapy is a new method of treatment of cancer. The purpose of this paper is to explore the effect of125|on proliferation, apoptosis and invasion in gastric cancer cells (BGC-823) as well as its possible machenism related to ERK signal transduction pathway, providing experimental evidence for the clinical application of125|seed in gastric cancer treatment.Methods The experiment conducted in two parts. In vitro: The irradiation model of125|seed was established on cultured gastric cancer cells BGC-823.The cell proliferation was detected by MTT, cell apoptosis and MMP were detected by flow cytometry cycle, and western blot was employed to analyze the expression levels of apoptosis related proteins Bax, Bel-2and phosphorylated ERK (p-ERK1/2); ERK agonist epidermal growth factor (EGF) was added as a counterevideace for the effect of125|on ERK pathway. In Vivo: Tumor-bearing nude mice with BGC-823gastric cancer cells were received125|seed implantation and were sacrificed after implantation6d,12d and24d, respectively. The tumor weight were observed in each group;the tumor tissue were sliced in parts for HE staining, transmission electron microscope to detect the cell apoptosis, flow cytometry to analyze on cell cycle, confocal observation of intracellular Ca2+in cells; fortelomerase protein, tumor vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were detected by ELISA, p-ERK1/2protein expression was detected by western blot.Results125|can significant inhibit the BGC-823cells proliferation by inducing G2/M phase arrest, decrease mitochondrial membrane potential and increase the rate of apoptosis in a dose dependent manner (P<0.05,P<0.01respectively); the apoptosis-related protein expression ratio of Bcl-2/Bax, p-ERK1/2expression were decreased (P<0.05,P<0.01respectively). EGF pretreatment significantly blocked125|seed irradiation-induced inhibition of cell proliferation by recovering the levels of Bcl-2/Bax and phosphorylated ERK (p-ERK) protein.(P<0.05). In vivo experiments further confirmed that125|can inhibit tumor growth in a time dependent way. BGC-823tumor-bearing mice interstitial implantation of125|6d,12d and24d can significantly reduce tumor mass and volume, destruction of tumor cell structure, decrease S phase cells; Increase intracellular Ca2+concentration, decrease telomerase protein and the telomerase reverse transcriptase, as well as VEGF, bFGF content and p-ERK1/2expression level; There was a close positive corelation between VEGF, bFGF content and p-ERK1/2expression level.Conclusions125|seed low-dose radiation can1) inhibit tumor cell proliferation by stoppage of cell cycle, decreased telomerase level;2) promote apoptosis process by reducing apoptosis-related protein Bcl-2/Bax ratio and increase intracellular Ca2+concentration;3) inhibit tumor cell invasion and metastasis by reducing VEGF, bFGF and p-ERK1/2levels. These inhibited effect can be recovering by EGF. Taken together, these data indicated that radioactive125|exerts effects of inhibition of cell proliferation, induce apoptosis and inhibit tumor invasion in gastric cancer cells by inactivating ERK signal transduction pathway. The results provide a scientific basis for the clinical application of125|in gastric cancer. |
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