Both cell lines were cultured in Roswell Park Memorial Institute (RPMI)-1640 moderate supplemented with 10% FBS (Thermo Fisher Scientific, Waltham, MA, USA) at 37C in a humidified atmosphere containing 5% CO2. Dose-dependent assay The Sichong tablets were ground into fine powder, dissolved in water, and then filtered by a 0.22 m filter. and time-dependent DPPI 1c hydrochloride manner. The IC50 values were 240 g/mL and 200 g/mL for AGS and MKN45 cells, respectively. Furthermore, we found that Sichong formula could inhibit the invasion and migration of gastric cancer cells, which might be mediated by the downregulation of MMP9 activity. Flow cytometry results indicated that Sichong formula induced apoptosis in gastric cancer cells through upregulation of Bax/Bcl2 ratio and activation of caspase cascade. The results from Western blot indicated that Sichong formula resulted in cell autophagy and inactivation of AKT signaling pathway. Conclusion Our data suggest that DPPI 1c hydrochloride Sichong formula inhibits the proliferation and migration and induces apoptosis in human gastric cancer cells. The inhibitory effect of Sichong formula was, at least partly, mediated by cell autophagy and AKT pathway. Keywords: apoptosis, invasion, migration, MMP9 Introduction Gastric cancer, the fourth most common cancer worldwide, has remained a major life-threatening disease for a long time.1 In addition, gastric cancer is the second leading cause of malignancy deaths in DPPI 1c hydrochloride the world, subsequent only to lung cancer, resulting in 650,000 deaths each year.2,3 Due to scarce early clinical manifestations and high tendency to metastasize, patients with gastric cancer are frequently diagnosed in advanced stages. Despite significant advances in surgical treatment, chemotherapy, and radiation therapy for cancer, the 5-12 months survival rate of gastric cancer remains poor, at approximately 20C30%.4 Therefore, it is urgently needed to explore new antitumor drugs with good efficacy and low toxicity for patients with gastric cancer. Traditional Chinese medicine (TCM) has been applied in China for thousands of years and is currently receiving great attention due to its multitarget and overall regulation in the treatment of tumors. Clinically, TCM is frequently used as adjuvant therapy during recovery of cancer patients and postsurgical radiotherapy and chemotherapy.5C7 According to in vitro and in vivo studies, TCM might be beneficial for gastric cancer patients by inhibiting the invasion of cancer cells, inducing apoptosis, suppressing prostate cancer dependent angiogenesis, and downregulating human androgen receptors.8,9 Sichong formula is composed of Earthworm (Dilong), Scolopendra (Wugong), Scorpion (Quanxie), and Eupolyphaga (Tubie). Sichong formula is usually a TCM compound from clinical experience, mainly used for the treatment of peripheral vascular diseases such as varicose vein of lower limbs, and it has been proved to induce apoptosis in hepatocellular carcinoma cells. However, as far as we know, there are no studies investigating the effects of Sichong formula on cellular behaviors of gastric cancer cells and the underlying mechanisms. In this study, we explored the antitumor properties of Sichong formula in AGS and MKN-45 gastric cancer cells. It was exhibited that Sichong formula could inhibit the proliferation and DPPI 1c hydrochloride induce apoptosis in AGS and MKN-45 cells. Moreover, Sichong formula restrained the metastatic capability of AGS and MKN45 cells. Mechanistically, we found that Sichong formula downregulated AKT pathway and UCHL2 induced cell autophagy through regulating protein expression. Materials and methods Cell culture Human gastric cancer cell lines (AGS and MKN45) and normal gastric mucosal epithelial cell line (GES-1) were purchased from American Type Culture Collection (Manassas, VA, USA). Both cell lines were cultured in Roswell Park Memorial Institute (RPMI)-1640 medium supplemented with 10% FBS (Thermo Fisher Scientific, Waltham, MA, USA) at 37C in a humidified atmosphere made up of 5% CO2. Dose-dependent assay The Sichong tablets were ground into fine powder, dissolved in water, and then filtered by a 0.22 m filter. When cell confluence reached 90%, AGS and MKN45 cells were trypsinized and prepared as a cell suspension. Then, the cells were seeded into a 96-well plate at 3000 cells per well and cultured 12 hrs for attachment. Subsequently, a medium made up of a gradient of Sichong formula was added to each well at a DPPI 1c hydrochloride final concentration of (0 g/mL, 5 g/ml, 10 g/mL, 20 g/mL, 40 g/mL, 80 g/mL, 120 g/mL, 160 g/mL, 200 g/mL, 300 g/mL, 400 g/mL, and 500 g/mL). After 48 hrs, 10 L of CCK8 reagent was added to each well, and the mixture was incubated for 1.5 hrs in a 37C incubator. The OD values at 450 nm were detected using a microplate reader (Multiskan Ex, Thermo Scientific, Waltham, MA, USA), and a dose-dependent curve was plotted to calculate IC50 values. Proliferation assays CCK8 assay Human gastric cancer cells were planted into a 96-well plate at a density of 3000 per well. After treatment with 80 g/mL of Sichong formula, cells in each well were added with 10 L CCK8 answer at regular time points (0 hrs, 24 hrs, 48 hrs,.