BACKGROUND:It is not fuly understood that whetherp53 inhibitor can directly intervene in the viability of bone marrow mesenchymal stem cels and the possible mechanism. OBJECTIVE:To investigate the effect of p53 inhibitor, PFT-α, on the aging process of bone marrow mesenchymal stem cels in late-phase amplification and to discover the key target to delay the replicative senescence of human bone marrow mesenchymal stem cels. METHODS:The expression levels ofp53,p21, andp15 mRNA in human bone marrow mesenchymal stem cels in both early and late-phase amplification were detected by quantitative PCR assay. Then, human bone marrow mesenchymal stem cels in late-phase amplification were respectively treated with 20 μmol/L PFT-α or an equivalent amount of dimethyl sulfoxide for 2 weeks. The positive rate of aging cels was determined by SA-β-Gal staining. The apoptosis was detected by TUNEL staining. Human bone marrow mesenchymal stem cels were treated with 300 μmol/L H2O2 for 30 minutes, and then celular anti-oxidative stress capacity was detected by cel counting kit-8 assay. RESULTS AND CONCLUSION:The quantitative PCR assay showed that the mRNA expression level ofp15, p21 andp53 in human bone marrow mesenchymal stem cels in late-phase amplification was significantly increased (1.45±0.23), (1.51±0.14) and (1.78±0.14) times as much as that in early phase amplification (P < 0.05). The positive rate of aging cels in PFT-α group was significantly lower than that in the dimethyl sulfoxide group[(41±5)%vs. (63±7)%,P < 0.05)]. However, there was no significant difference in apoptosis rate between PFT-α group and dimethyl sulfoxide group. After treatment with H2O2, the absorbance value in the PFT-α group was(1.27±0.13) times as much as that in the dimethyl sulfoxide group (P < 0.001). The above results demonstrate that the activation ofp53 signaling pathway may be an important factor of causing aging of human bone marrow mesenchymal stem cels. Application ofp53 inhibitor PFT-αcan enhance the anti-oxidative stress capacity of human bone marrow mesenchymal stem cels in late phrase amplification.

Objective To investigate the effect of expression of Cullin 4B (CUL4B) on the prognosis of patients after liver transplantation for hepatocellular carcinoma (HCC).Methods The retrospective case-control study was conducted.The clinicopathological data of 79 patients who underwent liver transplantation for HCC in the First Affiliated Hospital of Sun Yat-sen University between January 1,2014 and June 30,2015 were collected.The specimens of HCC tissues were collected and embedded in paraffin,and then were detected by immunohistochemistry staining.Observation indicators:(1) expression of CUL4B in HCC tissues;(2) follow-up and survival;(3) prognostic factors analysis after liver transplantation;(4) association between expression of CUL4B and recurrence and metastasis of tumor after liver transplantation.Follow-up using outpatient examination and telephone interview was performed to detect tumor recurrence or metastasis and survival up to June 2018.Measurement data with normal distribution were represented as (x)±s.The comparison between groups of count data was done using the chi-square test.The survival curve drawn using the Kaplan-Meier method,and the survival analysis was done by Log-rank test.The univariate and multivariate analysis were respectively done using the COX regression model.The association analysis was done using the Pearson test.Results (1) Expression of CUL4B in HCC tissues:immunohistochemistry staining showed that CUL4B was mainly expressed in the cytoplasm,with a powerful brownish-yellow staining.The high expression and low expression of CUL4B in HCC tissues were detected in 64 and 15 patients,respectively.(2) Follow-up and survival:79 patients were followed up for 38-56 months,with an average time of 46 months.During the follow-up,37 patients had no tumor recurrence and 42 had tumor recurrence (32 with tumor extrahepatic metastasis and 10 with intrahepatic metastasis);36 had survival and 43 died;the 1-and 3-year overall survival rates were respectively 86.84％ and 63.25％,and 1-and 3-year tumorfree survival rates were respectively 62.31％ and 51.27％.(3) Prognostic factors analysis after liver transplantation:① Results of univariate analysis showed that preoperative alpha-fetoprotein (AFP),Child-Pugh score,maximum tumour dimension,capsular invasion,intravascular tumor thrombus,Edmonson pathological grading and expression of CUL4B were related factors affecting the 3-year overall survival rate of patients after liver transplantation for HCC [Hazard Ratio (HR) =2.17,3.36,3.66,2.43,2.19,3.36,2.84,95％ confidence interval(CI):1.17-4.04,1.53-7.42,2.10-6.42,1.33-4.17,1.08-9.04,1.58-7.59,1.17-6.32,P＜ 0.05].The preoperative alpha-fetoprotein (AFP),Child-Pugh score,maximum tumour dimension,capsular invasion,intravascular tumor thrombus,Edmonson pathological grading and expression of CUL4B were related factors affecting the 3-year tumor-free survival rate of patients after liver transplantation for HCC (HR =2.06,3.72,3.16,2.36,2.83,3.21,1.69,95％CI:1.34-4.85,1.72-8.63,1.79-7.31,1.46-4.86,1.19-8.63,1.19-7.92,1.06-4.87,P＜0.05).② Results of multivariate analysis showed that maximum tumour dimension,intravascular tumor thrombus and expression of CUL4B were independent factors affecting the 3-year overall survival rate of patients after liver transplantation for HCC [Odds ratio(OR) =3.43,3.69,2.81,95％CI:1.16-6.02,1.96-9.38,1.04-9.63,P＜0.05].The maximum tumour dimension,intravascular tumor thrombus and expression of CUL4B were independent factors affecting the 3-year tumor-free survival rate of patients after liver transplantation for HCC (OR=2.25,4.72,2.74,95％C1:1.16-4.02,1.98-9.47,1.03-7.10,P＜ 0.05).The 3-year overall survival rate in patients with high-and low-expressions of CUL4B was respectively 66.7％ and 32.8％,with a statistically significant difference (x2 =5.69,P＜0.05).The 3-year tumor-free survival rate in patients with high-and low-expressions of CUL4B was respectively 73.3％ and 18.6％,with a statistically significant difference (x2 =4.63,P＜0.05).(4) Association between expression of CUL4B and recurrence and metastasis of tumor after liver transplantation:results of Pearson test showed that expression of CUL4B was significantly associated with HCC recurrence and metastasis after liver transplantation (r =0.62,P＜0.05).The further analysis showed that expression of CUL4B was significantly associated with extrahepatic metastasis after liver transplantation (r=0.84,P ＜ 0.05).Conclusion The expression of CUL4B is associated with HCC recurrence after liver transplantation,and it can be as a predictor for HCC recurrence and distant metastasis after liver transplantation.