Impact Of GRSF1 On The Malignance And Underlying Mechanisms In Gastric Cancer

[Objective] Gastric cancer is the fifth common cancer and the third leading cause of cancerrelated deaths globally at present.Tremendous progress has been made in recent years in diagnostic techniques and perioperative management of gastric cancer,the available treatments of gastric cancer include surgery,chemotherapy,radiation therapy,immunotherapy and molecular targeted therapy as well as a combination of modalities.However,the recurrence rate and metastasis rate of gastric cancer are still high,and even the patients who have received radical surgical resection often die of recurrence and metastasis of gastric cancer,the prognosis of gastric cancer is still poor.Therefore,there is an urgent need to explore the underlying mechanism of gastric cancer cell growth and metastasis.RNA-binding protein GRSF1,a member of the heterogeneous nuclear ribonucleoprotein F/H family,is a multifunctional protein that plays an important role in the regulation of cell senescence,embryonic development,skeletal muscle differentiation and cancer.However,whether GRSF1 is also involved in the malignance of gastric cancer is unknown.This study aims to explore the function roles of GRSF1 in gastric cancer and its underlying mechanism to identify the novel effective therapeutic targets.[Methods] First,we analyzed the expression of GRSF1 in gastric cancer tissues and normal gastric tissues as well as the relationship between GRSF1 expression and clinicopathological features using the public oncology database and the online data analysis website.Then,the expression of GRSF1 protein in normal gastric mucosa cells and various gastric cancer cell lines was detected by western blot.SGC-7901 and BGC-823 were selected for the biological experiments.The overexpressed and silenced plasmids as well as the corresponding control plasmids were obtained for transfection in SGC-7901 and BGC-823.The transfection efficiency was examined by Western blot.A success of cellular function experiments in vitro and in vivo were performed,including cell proliferation,migration,invasion,vasculogenic mimicry,epithelial-mesenchymal transformation,as well as tumor growth and metastasis.The involved biological pathways were also explored.[Results] The expression of GRSF1 protein in gastric cancer tissues was significantly higher than that in normal gastric tissues,and the high expression of GRSF1 was associated with the poor prognosis of gastric cancer patients.The methylation level of GRSF1 promoter was significantly correlated with TP53 mutation in gastric cancer.The normal expression of GRSF1 in most gastric cancer cell lines was higher than that in GES-1,particularly in SGC-7901 and BGC-823.Thus,SGC-7901 and BGC-823 were selected for sequent biological experiments.The expression efficiency of GRSF1 in SGC-7901 and BGC-823 transfected with the corresponding plasmids was confirmed by Western blot.In vitro,the overexpressed GRSF1 promoted cell proliferation,migration,invasion,adhesion,epithelial-mesenchymal transformation and vasculogenic mimicry while knockdown of GRSF1 showed the opposite effect in gastric cancer cells.In vivo,the knockdown of GRSF1 inhibited subcutaneous tumor growth and lung metastasis.In addition,the overexpression of GRSF1 up-regulated p-Akt protein expression while the knockdown of GRSF1 down-regulated p-Akt protein expression without affecting t-Akt protein expression in vitro and in vivo,indicating that GRSF1 regulates PI3K/ Akt pathway in gastric cancer.[Conclusion] For the first time,the study identified that GRSF1 plays an important role in gastric cancer acting as an oncogene.It was first demonstrated that GRSF1 not only promotes tumorigenesis but also enhances metastasis and vasculogenic mimicry formation which were both mediated by epithelial-mesenchymal transformation.GRSF1 is involved in cell proliferation,migration,invasion,adhesion,vasculogenic mimicry formation,epithelialmesenchymal transition and metastasis through PI3K/ Akt pathway in gastric cancer.GRSF1 may be a potential effective therapeutic target and an indicator of malignance of gastric cancer.