The Roles And Mechanism Of Profilin-1in Human Gastric Cancer

Background:Gastric cancer，a most common digestive malignancy, is the second mostcommon cause of cancer deaths mainly caused by tumor invasion and metastasisworldwide. Thus, it is necessary to investigate mechanism of tumor invasion andmetastasis. Cell migration, a fundamental aspect of tumour cell invasion andmetastasis, involves dynamic remodelling of actin cytoskeleton via concerted actionsof many different classes of actin-binding proteins (ABPs). Profilin-1(PFN1), aimportant ABPs, has been detected in many types of human cancers and is correlatedwith the tumor malignancy and the prognosis of patient. However, the role of PFN1ingastric carcinoma is unclear. In this study, we investigated the contribution of PFN1and its molecular mechanisms in gastric cancer.Methods:Firstly, dectecting PFN1expression and relationship with clinicalparameters: PFN1expression was detected in tissue array withimmunohistochemical analysis, including75gastric cancer tissues and theircorresponding non-plastic gastric mucosal tissues. The result was verified throughdetecting PFN1expression in another18frozen cases of gastric cancer and pairedadjacent normal tissues via Western-blot and QRT-PCR. Furthermore, PFN1expression in the gastric cancer epithelial cell lines AGS, MKN28, SGC-7901,BGC-823, N87, and the human immortalized gastric mucosa epithelial cell line wasdetermined by Western blot and qRT-PCR to deeply verify our result. At last, theassociation of PFN1expression with patient clinicopathological characteristics,including Gender, Age, Tumor location, Tumor size, Tumor differentiation, Tumorinfiltration, Lymph node metastasis, and TNM stage was analyzed.Secondly, analyzing its biologic function: The appropriate gastric cancer cellline was screened to detect biological fuction, including cell proliferation assay,colony formation assay, cell cycle analysis, transwell assay and invasion assay,influenced by PFN1-SiRNA interference.At last, dectecting its molecular mechanisms: The expression of integrin β1and activity of focal adhesion kinase (FAK) and their downstream proteins wasmeasured by Western-blot. At last, the related cell signaling influenced by PFN1was identified by the fibronectin (FN)Results:Among the75paired gastric cancer samples,53(70.4%) carcinomas showedhigher PFN1expression than the matched adjacent normal tissues. Furthermore, Highexpression of PFN1, which was confirmed by H score (P<0.01), was associated withtumor infiltration (P <0.05), lymph node metastasis (p <0.05) and TNM stage (P <0.05), but not correlated with gender, age, location, tumor size, histologicaldifferentiation (p>0.05). In vitro, the SGC-7901cell line with relatively higher PFN1expression were transfected with PFN1-SiRNA and knocking down PFN1inhibitedproliferation by inducing G0/G1arrest in SGC-7901cells. In addition, silencingPFN1attentuated the gastric cancer cell ability of migration and invasion, and alsodown-regulated the expression of MMP2and MMP9.Moreover, the expression ofintegrin β1and the activity of FAK, as well as its downstream effectors ERK1/2,P38MAPK, PI3K, AKT, mTOR were inhibited after silencing PFN1. At last, the cellsignaling mediated by PFN1was identified by the fibronectin (FN)Conclusions: Our findings suggest that PFN1have higher expression ingastric cancer and high expression of PFN1is correlated with tumor infiltration (P <0.05), lymph node metastasis (p <0.05) and TNM stage (P <0.05). Silencing PFN1inhibits gastric cancer cell proliferation, migration and invasion likely via influencingintegrinβ1/FAK signling pathway.