Forkhead Box K1 Regulates The Proliferation,invasion And Migration Of Gastric Cancer By Inhibiting Autophagy

Objective:Gastric cancer(GC)is the fifth most common malignant tumor in the world and the third leading cause of cancer death.In 2012,gastric cancer caused more than 320,000 deaths in China,accounting for approximately 45%of global deaths from gastric cancer.This shows that gastric cancer is still one of the main causes of cancer burden in the Chinese population.In recent years,the diagnosis and treatment techniques for gastric cancer have greatly improved,but due to local recurrence and distant metastasis,the five-year survival rate of gastric cancer is still very low.Therefore,to clarify the molecular mechanism of gastric cancer metastasis is an important and urgent problem to be solved in the treatment of gastric cancer..Forkhead box K1(FOXK1)belongs to the FOX family and is a transcription factor that contributes to cancer development and is related to the occurrence and development of various tumors.At present,there are preliminary reports on FOXK1 in ovarian cancer,colorectal cancer and glioblastoma.But it is unclear how FOXK1 regulates the proliferation and migration of gastric cancer cells.Autophagy is a highly evolutionarily conserved mechanism,and its role in cancer cells is controversial.It seems that its role depends on the type and stage of the tumor and the intensity of the stimulation induced by autophagy.Little is known about the molecular mechanism and exact function between FOXK1 and autophagy.Therefore,the purpose of this study is to investigate the clinical significance and biological function of FOXK1,and molecular mechanism between FOXK1 and autophagy in GC.Methods:First,bioinformatics was used to verify FOXK1 expression,and the correlation between the overall survival(OS)of GC patients and FOXK1 expression was analyzed.The frozen tissues and adjacent tissues of 43 gastric cancer patients with clear pathological diagnosis after operation were collected.Tissue microarrays(TMAs)analysis detects the expression level of FOXK1 in cancer tissues and adjacent tissues.Chi-square test was used to analyze the correlation between FOXK1 and the patient's gender,age,gastric tumor location,HER2 expression,pathological differentiation,microvascular tumor thrombosis,lymph node metastasis,TNM stage,and capsule invasion.Next,Western blotting and q-PCR technology were used to verify the expression and transfection efficiency of FOXK1 in gastric cancer cells.EdU experiment was used to analyze the proliferation of overexpressing FOXK1 and low expressing FOXK1.Cell scratches and Transwell experiments verified the invasion and migration ability of gastric cancer cells after overexpression and low expression of FOXKI.Western blotting,immunofluorescence and electron microscopy were used to observe the correlation between FOXK1 and autophagy.In addition,through the KEGG pathway signal analysis and Western blotting,we found the relationship between FOXK1 and phosphoinositide 3 kinase(PI3K)/AKT/rapamycin mammalian target(mTOR)pathway.Finally,in vivo experiments verified the effect of knockdown of FOXK1 on the growth of tumors by subcutaneous injection in mice.Results:The expression level of FOXK1 is abnormally increased in gastric cancer tissues,and the overall survival rate is lower as the expression of FOXK1 is higher.High levels of FOXK1 are associated with pathological differentiation,microvascular tumor thrombosis,lymph node metastasis,TNM stage and capsule invasion,but not with gender,age,tumor location or HER2 expression in the tumor.It was further found that FOXK1 promotes the proliferation,invasion and transfer of GC by regulating autophagy via activation of the class I phosphoinositide 3-kinase(PI3K)/AKT/mammalian target of rapamycin(mTOR)pathway and inhibition of the expression of class III PI3K.In addition,in vivo experiments also confirmed that FOXK1 has the tumor-promoting effect.Conclusions:In summary,our results indicate that FOXK1 can be used as an independent prognostic indicator for patients with gastric cancer.We also provide new targets for the comprehensive treatment of GC by emphasizing the relationship between FOXK1 and GC malignant behavior.