Mechanism Study On The Inhibition Effect Of As₂O₃ On Invasion And Migration Of Human Gastric Cancer SGC-7901 Cells

Gastric cancer is one of the most common human malignancies which ranks the second in incidence and mortality. Most gastric cancer patients eventually succumb to the consequences of metastasis tumor rather than the primary tumor itself. Therefore, inhibition of invasion and migration in gastric cancer cells would be helpful in improving survival. As a commonly used agent for tumor therapy, Arsenic trioxide (AS₂O₃) was reported to regulate many cell functions, such as proliferation, apoptosis, differentiation, and angiogenesis in promyelocyte leukemia and esophageal, breast and gastric cancer cells. Recently, several investigators demonstrated that AS₂O₃ could inhibit tumor invasion and migration. However, the precise mechanism of the inhibition of invasion activity by AS₂O₃ is less understood.In the present study, human gastric cancer SGC-7901 cells were chosen in searching for the effects of AS₂O₃ on invasion and migration, intracellular Reactive oxygen species (ROS) levels, the expression of Cyclooxygenase-2 (Cox-2) and Matrix metalloproteinase-2 (MMP-2). Moreover, N-acetyl-L-cysteine (NAC, radical scavenger) and Celecoxib (Cox-2 inhibitor) were also used to further explore whether ROS plays a role in the inhibition of invasion and migration through the regulation of the expression of Cox-2 and MMP-2 in As₂O₃-treated SGC-7901 cells.4,5 Dimethythiazoyl-zyl 2,5-diphenylterrazjolium bromiole (MTT), invasion, migration and wound healing assays were used to test cell-matrix adhesion, invasion and migration activities, and cellular motility.2,7-Dichlorofluorescin-diacetate (DCHF-DA) assay was for analyzing intracellular ROS, Real time RT-PCR and Western blotting were employed to analyze the expression of MMP-2 and Cox-2. The levels of Prostaglandin E2 (PGE2)/Thromboxane B2 (TXB2)/Leukotriene B4 (LTB4) were measured by Enzyme-linked immunosorbnent assay (ELISA). The results were as follows:1. AS₂O₃ (except for low-level group) significantly inhibited invasion/migration in SGC-7901 cells at 24 h (P<0.05), whereas, no significant changes were found in cell-matrix adhesion (except for high-level group) (P>0.05).2. AS₂O₃ (1,2μM) significant decreased the expression of MMP-2 and Cox-2, as well as intracellular PGE2 level (P<0.05), whereas intracellular LTB4 and TXB2 levels were not affected. In contrast, intracellular ROS were increased dramatically (P<0.05).3. NAC significant inhibited intracellular ROS and restored the expression of Cox-2 and MMP-2 and invasion/migration activity in As₂O₃-treated cells. (P<0.05).4. Celecoxib further decreased Cox-2, MMP-2, and PGE2 expression and inhibited invasion/migration activity in AS₂O₃-treated cells (P<0.05).In conclusion, the results of the present study showed that AS₂O₃ could inhibit invasion/migration in SGC-7901 cells by decreasing MMP-2, PGE2, and Cox-2 expression and increasing intracellular ROS levels. The generation of ROS play a critical role in inhibiting invasion/migration by suppressing the Cox-2/MMP-2 pathway in As₂O₃-treated SGC-7901 cells and regulating intracellular ROS levels may be a promising strategy in gastric cancer therapy.