Follistatin Like 5 ( FSTL5) inhibits epithelial to mesenchymal transition in hepatocellular carcinoma

Background:Epithelial to mesenchymal transition(EMT)is a key process in determining distant metastasis and intra-hepatic dissemination of hepatocellular carcinoma(HCC).Follistatin(FST)family members are considered to be an attractive therapeutic targets and prognostic indicators in cancers.As a derivative of FST,Follistatin Like 5(FSTL5)may play a similar role in HCC cells.This study aimed to investigate the expression and function of FSTL5 in HCC and its role in EMT.Methods:FSTL5,E-cadherin and vimentin in HCC,and paracancerous tissues were detected by immunohistochemistry.Correlation of FSTL5 expression with overall survival was assessed.The proliferation and invasion of HCC cell lines SK-Hep1 and MHCC-LM3 were analyzed by cell counting kit-8 and Transwell assays.The expression of FSTL5,E-cadherin,and vimentin in HCC cells was examined by polymerase chain reaction and Western blot analysis.T-test was used to analyze the difference in proliferation and invasion ability between groups.The Spearman rank correlation test was used to detect the correlation between the expression of FSTL5 and E-cadherin or vimentin.Results:The expression of FSTL5 in HCC was lower than that in paracancerous tissues(9.97%vs.82.55%,χ2=340.15,P<0.001).Patients with high FSTL5 expression had a better prognosis(χ2=8.22,P=0.004)and smaller tumor diameter(χ2=45.52,P<0.001),less lymph node metastasis(χ2=5.58,P=0.02),earlier tumor node metastasis stage(χ2=11.29,P=0.001),a reduced number of tumors(χ2=5.05,P=0.02),lower alpha-fetoprotein value(χ2=24.36,P<0.001),more probability of hepatitis carrying(χ2=40.9,P<0.001),and better liver function grade(χ2=5.21,P=0.02).Immunohistochemistry showed that FSTL5 expression in HCC tissues was positively correlated with E-cadherin expression(r=0.38,P<0.001)and negatively correlated with vimentin expression(r=-0.385,P<0.001).Furthermore,over-expression of FSTL5 up-regulated the expression of E-cadherin and down-regulated the expression of vimentin in SK-Hep1(negative control[NC]vs.FSTL5-interfering group[Lv-FSTL5]:E-cadherin[t=45.03,P<0.001],vimentin[t=67,P<0.001])and MHCC-LM3(NC vs.Lv-FSTL5:E-cadherin[t=50,P<0.001],vimentin[t=72.75,P<0.001])cells at mRNA level.The same as protein level.In addition,the over-expression of FSTL5 inhibited the proliferation(NC vs.Lv-FSTL5:SK-Hep1,3 d[t=7.324,P=0.018],4 d[t=6.23,P=0.021],5 d[t=10.21,P=0.003];MHCC-LM3,3 d[t=4.32,P=0.037],4 d[t=7.49,P=0.012],5 d[t=9.3661,P=0.009])and invasion(NC vs.Lv-FSTL5:SK-Hep1,t=21.57,P<0.001;MHCC-LM3,t=18.04,P<0.001)of HCC cells.Conclusions:Down-regulation of FSTL5 may contribute to EMT of HCC,and FSTL5 is a potential target in the treatment of HCC.