Perfluorooctanoic Acid Induces Human Ishikawa Endometrial Cancer Cell Migration And Invasion Through Activation Of ERK/mTOR Signaling

Objective:Perfluorooctanoic acid(PFOA)is a synthetic and persistent organic pollutant found in the environment.Because it is stain-and water-resistant,it is widely used in manufacturing and is found in nearly everything in the environment including drinking water.PFOA is associated with multiple diseases,including kinds of tumorigenesis.However,whether PFOA exposure could induce the incidence of endometrial carcinoma and the underlying molecular mechanism remain largely unknown.Epithelial-mesenchymal transition(EMT)promotes tumor cell motility and invasion.Down-regulation of cell surface markers such as E-cadherin is one of the first alterations during metastatic progression.In our present research,We explored the molecular mechanisms underlying PFOA-induced endometrial cancer cell invasion and migration.Methods:Ishikawa and ECC1 cells were maintained in RPMI-1640 media.Cell migration was assessed using wound-healing and Trans well invasion assays.The cells were incubated for additional 48 hours in serum free RPMI-1640 in the presence of 0 or 50 nM PFOA,rapamycinalone,or rapamycin(added 24 hours before PFOA stimulation)and PFOA.The cells were harvested for Western blotting,Quantitative real-time PCR and Immunofluorescence.Ishikawa cells(1 x 107)were suspended in 200μL of cold PBS and injected subcutaneously into the left upper flank of the female BALB/c nude mice(6-week-old).Tumor diameters were measured and tumor tissues were sectioned for immunohistochemical analysis.Results:Though cell proliferation was only slightly elevated,PFOA exposure significantly enhanced migration and invasion of Ishikawa endometrial cancer cells and was associated with a dramatic decrease in epithelial-mesenchymal transition(EMT)-associated marker E-cadherin expression.Furthermore,mTOR signaling was activated upon PFOA stimulation and this activation is ERK1/2 pathway dependent,while AKT phosphorylation was not affected.Treatment with mTOR inhibitor rapamycin not only antagonized the PFOA induction effects on Ishikawa cells,but also reversed the effect of PFOA on xenogrant mouse tumorigenesis.In line with the above findings,rapamycin pretreatment abolished the effect of PFOA on inhibiting E-cadherin expression.Conclusions:In our present study,we showed it for the first time that PFOA stimulation can also significantly enhance endometrial carcinoma Ishikawa cell migration and invasion in vitro and tumorigenensis in vivo,and the mechanism is that PFOA regulates endometrial carcinoma cell migration and invasion through activation of ERK/mTOR signaling,which could promote tumorigenesis.