ABSTRACT
Objective To investigate the effect of nuclear factor erythroid-2-related factor 2(Nrf2) on the anti-hypoxia and anti-apoptotic ability of mesenchymal stem cells(MSCs). Methods Human embryonic kidney cells(293FT) were transfected with recombinant plasmid which overexpressed Nrf2 and helper plasmid. High-titer lentivirus which overexpressed Nrf2 were obtained. MSCs were transfected with lentivirus with Nrf2 overexpression and empty lentiviral vector to establish Nrf2-MSCs which stably overexpressed Nrf2 (Nrf2 overexpression group) and green fluorescent protein (GFP)-MSCs(control group). The expression of green fluorescent in 2 groups was observed by fluorescence microscope. The expression level of Nrf2 protein in 2 groups was measured by Western Blot. The anti-hypoxia ability of 2 groups was observed by light microscope. The anti-apoptotic ability of 2 groups was measured by flow cytometry. Results Nrf2-MSCs which stably overexpressed Nrf2 were successfully established. Western Blot analysis revealed that the expression level of Nrf2 protein in the Nrf2 overexpression group was significantly higher than that in the control group(P<0.01). After 15 h hypoxia treatment, the cell activity in the Nrf2 overexpression group was significantly higher than that in the control group. Flow cytometry showed that the apoptosis rate in the Nrf2 overexpression group was (30.9±1.4)%, significantly lower than (61.3±1.3)% in the control group(P<0.05). Conclusions Nrf2-MSCs which can stably overexpress Nrf2 possess certain anti-hypoxia and anti-apoptotic ability in hypoxia environment.
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Objective To investigate the correlation between the Yes-associated protein (YAP) expression and epithelial-mesenchymal transition (EMT) by transiently transfecting with YAP small-interfering RNA (siRNA) in MHCC97H and MHCC97L cells.Methods MHCC97H and MHCC97L cells were transiently transfected by YAP siRNA.Furthermore,protein expressions and mRNA levels of characteristic markers of EMT (E-cadherin,N-cadherin) were examined by Western blotting and real-time polymerase chain reaction.Transwell invasion assay was used to detect changes of invasiveness of MHCC97H and MHCC97L cells.Results The YAP siRNA transfected group in MHCC97H was examined after 72 hours by Western blotting.The result showed obviously higher expression of E-cadherin in transfected group compared with the control group (P ＜ 0.05),and lower expression of N-cadherin (P ＜ 0.05).In MHCC97L cells,the expression of E-cadherin was also significantly increased (P ＜ 0.05),however,N-cadherin expression did not significantly change (P ＞ 0.05).Moreover,compared with the control group,transwell invasion assay showed that the number of the transfected group cells significantly decreased in MHCC97H(66 ± 6.89 vs 117 ± 7.23,P ＜ 0.05),and compared with the control group,the number of the transfected group also significantly decreased in MHCC97L (40 ±2.65 vs 77 ±4.33,P ＜0.05).The result of real-time polymerase chain reaction indicated that mRNA levels of E-cadherin increased (P ＜ 0.05),but mRNA levels of N-cadherin did not significantly change (P ＞ 0.05).This is considered as post-transcriptional regulation after silencing YAP in MHCC97H and MHCC97L.Conclusions YAP silencing is able to inhibit EMT in MHCC97H and MHCC97L cells by modulating the characteristic markers of EMT.The inhibition of YAP expression can reduce the invasion ability of hepatocellular carcinoma cells.
ABSTRACT
Objective To investigate the expression of Hippo pathway component in hepatic cancer tissues and investigate its effects on the tumor recurrence after Iiver transplantation.Methods The clinical data of 105 patients with liver cancer who were admitted to the Third Affiliated Hospital of Sun Yat-Sen University from July 2004 to September 2009 were retrospectively analyzed.The samples of liver cancer tissues were collected.The maximum diameter,number of foci,blood vessel involvement,preoperative level of alpha-fetoprotein (AFP),results of postoperative pathological examination were analyzed.All the patients were followed up via out-patient examination,mail and phone call.Patients were followed up once a week within the first month after operation,and once a month within the 6 months after operation,and then once every 3 months at 1 year later.The follow-up ended in December 2012 or tumor recurrence.The disease-free survival time began at the date of operation and ended at the time of tumor recurrence.The expressions of Yes-associated protein (YAP),phosphorylated YAP,Hippo pathway component (Lats1/2,pLats1/2,Mst1,pMst1/2) were detected by immunohistochemical staining.All data were analyzed using the chi-square test or Student t test.Factors might influence the postoperative tumorfree survival time after liver transplantation were analyzed using the Cox regression model.The survival curve was drawn by Kaplan-Meier method,and the disease-free survival was analyzed using Log-rank test.Results Positive expressions of YAP and phosphorylated YAP were detected in the nucleus and cytoplasm,and the positive expressions of Lats1/2,pLats1/2,Mst1 and pMst1/2 were detected in the cytoplasm.The positive expressions of YAP,phosphorylated YAP,Latsl/2,pLats1/2,Mst1 and pMst1/2 protein were 51.43％ (54/105),55.24％ (58/105),45.71％ (48/105),9.52％ (10/105),64.76％ (68/105) and 20.00％ (21/105),respectively.The positive expression of YAP was correlated with the tumor diameter,venous infiltration and AJCC stage (x2=4.173,9.611,7.233,P ＜ 0.05).The positive expression of Lats1/2 protein was correlated with tumor diameter and AJCC stages (x2=14.413,7.969,P ＜ 0.05).The positive expression of Mst1 protein was correlated with the tumor diameter (x2=4,129,P ＜0.05).The results of univariate analysis showed that the protein expressions of YAP,Lats1/2,pMst1/2,age,tumor diameter,tissue differentiation,preoperative level of AFP,venous infiltration and AJCC stages were risk factors influencing tumor recurrence after liver transplantation (HR =2.603,0.502,1.802,0.955,3.559,2.395,2.414,2.915,2.086,95％ CI:1.452-4.666,0.287-0.880,1.040-3.123,0.931-0.981,1.921-6.595,1.475-3.889,1.313-4.337,1.604-5.229,1.370-3.176,P ＜ 0.05).The results of multivariate analysis showed that the positive expression of YAP,tumor diameter ＞ 5 cm,low differentiation of tissue and AJCC stages Ⅲ were independent risk factors influencing tumor recurrence after liver transplantation (HR=2.011,2.176,2.390,1.574,95％CI:1.115-3.628,1.125-4.206,1.448-3.945,1.041-2.381,P ＜ 0.05).The median time of follow-up was 13.0 months (range,1.0-96.0 months).Eight patients missed follow-up.Fifty-four patients had tumor recurrence,and the mean time of tumor recurrence was 6.7 months (range,1.0-41.0 months).The disease-free survival time of patients with positive expression of YAP were significantly shorter than those with negative expression of YAP (Log-rank value =12.890,P ＜ 0.05).Conclusions Positive expressions of YAP and phosphorylated YAP were detected in the nucleus and cytoplasm,and the positive expressions of Lats1/2,pLats1/2,Mst1 and pMst1/2 were detected in the cytoplasm.The positive expression of YAP is the independent risk factor for tumor recurrence after liver transplantation.