Upon activation of TGF-, Smad2 is phosphorylated and undergoes dimerization with Smad3, thus permitting its translocation into nucleus [24]. HepG2 cells. ESC could reverse the mesenchymal morphology and regulate expressions of marker proteins in HepG2 induced by TGF- and significantly inhibit TGF- induced HepG2 cell migration and invasion. We further found that ESC could also significantly depress Smad2 phosphorylation and nuclear translocation, and ESC had coordination with SB432542, a specific inhibitor of TRI kinases. == Findings == These results suggested that the ESC could reverse epithelial mesenchymal transition induced by TGF- via inhibition Smad2 signaling pathway. Keywords: Hepatocellular carcinoma, Stellera chamaejasmeL., Transforming growth factor, Metastasis, Epithelial mesenchymal transition, Smad signaling pathway == Background == In recent years, it is discovered that epithelial mesenchymal transition (EMT) is an important biological process for malignant tumor cells to obtain migratory and invasive ability and a key initiative step of invasion and metastasis in tumors. EMT is characterized by up-regulation of mesenchymal markers (such because Vimentin) down-regulation of epithelial markers (such as E-cadherin) [1], and lack of cellcell adhesion, which enables tumor cells to dissociate and migrate from the primary tumor [2]. Because EMT is closely related to the proliferation, metastasis and prognosis of malignant tumor, it has become an important hot spot intended for pharmacological studies on tumors [3]. Transforming growth factor (TGF-) is one of the most important signal molecular that can initiate the EMT process [4]. During TGF–mediated EMT, TGF- initiates responses by contacting two types of transmembrane serine/threonine kinases called receptors type I and type II, promoting activation from the type I by the type II kinase. The activated type I receptor then propagates the signal to the nucleus by phosphorylating Smad2 and Smad3. Once phosphorylated, Smad2 and Smad3 associate with all the shared partner Smad4 and the complexes collect in the nucleus L-Asparagine where they regulate the expression FLI1 of TGF- target genes through cooperative interactions with transcriptional partners, which is process of the classical Smad-dependent signaling pathway that TGF- induced [5, 6]. Many studies showed that a variety ofStellera chamaejasmeL. L-Asparagine extracts or monomers had anti-tumor activities and could induce apoptosis L-Asparagine of tumor cells [710]. Our previous studies also got the same results [11, 12], but there were no experiments on its anti-metastasis effects. In this study, we further noticed the effects of ESC on TGF–mediated EMT and classical Smad-dependent signaling pathway in HepG2 liver cancer cells. == Methods == == Cell line and cell culture == HepG2 liver cancer cell lines were preserved in Beijing Institute of Hepatology. HepG2 cells L-Asparagine were cultured in DMEM medium (Gibco, Grand Island, NY, USA) supplemented with 10 % fetal bovine serum (China Hangzhou Sijiqing Biological Technology Co., Ltd) and managed at 37 C in a humidified incubator with 5 % CO2. == Reagents and antibodies == Process of ESC (Extract ofStellera ChamaejasmeL. ) and determination of part components of ESC was provided in another paper [11]. Trypsin-ethylene-diaminetetraacetic acid (EDTA) and DMEM medium were purchased from Gibco (Grand Island, NY, USA); 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT), dimethyl sulfoxide (DMSO) and SB431542 were provided by Sigma Chemical Co. (St. Louis, MO, USA); TGF- was from R&D Systems (Miniieapolis, MN, USA); E-cadherin, Vimentin and -actin primary monoclonal antibody were purchased by Abcam Ltd (Cambridgem MA, USA); Matrigel was from BD Biosciences (Los Angeles, CA, USA); Crystal violet was from Beijing Solarbio Science and Technology Co., Ltd; Smad and p-Smad primary monoclonal antibody were from Cell Signal Technology, Inc (Beverly, MA, USA). == MTT assay == Cells in the logarithmic growth phase were plated in 96-well dishes in a seeding density of 5000 cells/well and incubated in a 37 C incubator with 5 % CO2overnight. After cells were treated with ESC (final concentration was respectively, 100, 50, 25, 12. 5, 6. 25, three or more. 125, 1 . 562, 0 g/mL) intended for 24, 48, 72 h, the culture medium in each well was left behind, incubating with 0. 5 g/L MTT 100 L for 4 h. After that each well was added with 150 L DMSO and vibrated for 10 min, and absorbance of each well was detected with microplate reader (ELX800 type, BIO-TEX Devices, INC, Winooski, VT, USA) at the 490 nm wavelength. The inhibition rate (IR) was calculated as follows: VENTOSEAR (%) = (1 ODtreatment/ODcontrol) 100 %. Then half-maximal inhibitory concentration (IC50) L-Asparagine was determined by logistic method. == Scattering assay == Cells (2 104) were seeded in each well of 24-well.
