TOB1 Deficiency Enhances the Effect of Bone Marrow-Derived Mesenchymal Stem Cells on Tendon-Bone Healing in a Rat Rotator Cuff Repair Model.

BACKGROUND/AIMS: This study investigated the effect of silencing TOB1 (Transducer of ERBB2, 1) expression in bone marrow-derived mesenchymal stem cells (MSCs) on MSC-facilitated tendon-bone healing in a rat supraspinatus repair model. METHODS: Rat MSCs were transduced with a recombinant lentivirus encoding short hairpin RNA (shRNA) against TOB1. MSC cell proliferation was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. The effect of MSCs with TOB1 deficiency on tendon-bone healing in a rat rotator cuff repair model was evaluated by biomechanical testing, histological analysis and collagen type I and II gene expression. An upstream regulator (miR-218) of TOB1 was determined in MSCs. RESULTS: We found that knockdown of TOB1 significantly increased the proliferative activity of rat MSCs in vitro. When MSCs with TOB1 deficiency were injected into injured rat supraspinatus tendon-bone junctions, the effect on tendon-bone healing was enhanced compared to treatment with control MSCs with normal TOB1 expression, as evidenced by elevated levels of ultimate load to failure and stiffness, increased amount of fibrocartilage and augmented expression of collagen type I and type II genes. In addition, we found that the TOB1 3' untranslated region is a direct target of miR-218. Similar to the effect of TOB1 deficiency, overexpression of miR-218 effectively promoted tendon-bone healing in rat. CONCLUSION: These results suggest that TOB1 may play a negative role in the effect of MSCs on tendon-bone healing, and imply that expression of TOB1 may be regulated by miR-218.

Tumor necrosis factor-α attenuates starvation-induced apoptosis through upregulation of ferritin heavy chain in hepatocellular carcinoma cells.

BACKGROUND: Tumor microenviroment is characteristic of inflammation, ischemia and starvation of nutrient. TNF-α, which is an extraordinarily pleiotropic cytokine, could be an endogenous tumor promoter in some tumor types. The basic objective of this study was to investigate the effects of TNF-α on the cell viability and apoptosis of hepatocellular carcinoma cells under serum starvation, and to identify the molecular mechanisms involved. METHODS: For this purpose, five different concentrations of TNF-α and two different serum settings (serum-cultured and serum-deprived) were used to investigate the effects of TNF-α on the cell viability and apoptosis of Hep3B and SMMC-7721 cells. RESULTS: TNF-α (10 ng/ml) attenuated serum starvation-induced apoptosis of hepatocellular carcinoma cells, and autophagy conferred this process. BAY11-7082, a specific inhibitor of NF-κB, reversed the suppression of serum starvation-induced apoptosis by TNF-α. Moreover, TNF-α-induced NF-κB transactivation was suppressed by autophagy inhibitor 3-MA. In addition, TNF-α up-regulated Ferritin heavy chain (FHC) transiently by NF-κB activation and FHC levels were correlated with the TNF-α-induced protection against serum starvation-mediated apoptosis of hepatocellular carcinoma cells. Furthermore, FHC-mediated inhibition of apoptosis depended on suppressing ROS accumulation. CONCLUSIONS: Our findings suggested that autophagy conferred the TNF-α protection against serum starvation-mediated apoptosis of hepatocellular carcinoma cells, the mechanism involved with the activation of the TNF-α/ NF-κB /FHC signaling pathway.

The protective or damaging effect of Tumor necrosis factor-α in acute liver injury is concentration-dependent.

BACKGROUND: Inflammatory cytokine is important in modulating injured diseases. Tumor necrosis factor-α (TNF-α), one of potent inflammatory cytokines, plays a dominant role in host defense reaction. However, the concrete effect of TNF-α on acute liver injury is totally unclear. Here we reported the concrete effect and possible mechanisms of TNF-α on acute liver injury induced by carbon tetrachloride (CCl4). METHODS: SD male rats were equally divided into nine groups. CCl4 (1 ml/kg) was subcutaneously injected into the rats. Enbrel, a TNF-α inhibitor, were intraperitoneally injected at dose of 0, 0.25, 0.5, 1, 2, 4 or 8 mg/kg 15 min before the CCl4 injection. 24 h later, rats were sacrificed. Serum ALT and AST were measured with an autoanalyzer. Serum TNF-α were measured by ELISA. HE staining was used to observe the liver tissue morphology. Hepatocellular apoptosis were tested by immunochemistry and Tunnel kit. Inflammatory factors, involve IL-4, IL-6, IL-8, IL-ß and IFN-γ were detected by RT-PCR. The NF-κB signal pathway and anti-apoptotic genes include Bcl-XL, FHC, XIAP and Bcl-2 were measured by western-blotting and RT-PCR. RESULTS: The change of liver function presented an obvious "V" shape in the whole process of persistently increased Enbrel. As Enbrel was increased gradually from 0 to 1 mg/kg, serum TNF-α were blocked, ALT and AST were gradually decreased as TNF-α as well as the numbers of hepatocellular apoptosis, and were declined to the minimum at 1 mg/kg Enbrel. As Enbrel was increased gradually from 1 to 8 mg/kg, ALT, AST and hepatocellular apoptosis were increased instead, and reached to the maximum at 8 mg/kg Enbrel. HE showed that the seriousness of hepatocellular steatosis was the most at 8 mg/kg Enbrel, and second at 0 mg/kg, the weakest at 1 mg/kg in the acute liver injury. Western-blotting and RT-PCR showed NF-κB, p-IκBα and antiapoptotic genes include Bcl-XL, FHC, XIAP, Bcl-2 were decreased as TNF-α was blocked by increased Enbrel. CONCLUSION: Our results suggested that TNF-α had a dual role in acute liver injury. It was regulated might via the corporate effect of NF-κB signal pawahway and anti-apoptosis. Meanwhile, our findings provide a reference for clinical treatment of acute liver injury.

Tumor-associated macrophages promote cancer stem cell-like properties via transforming growth factor-beta1-induced epithelial-mesenchymal transition in hepatocellular carcinoma.

Tumor-associated macrophages (TAMs), a crucial component of immune cells infiltrated in tumor microenvironment, have been found to be associated with progression and metastasis of hepatocellular carcinoma (HCC). In this study, we aimed to clarify the mechanism underlying the crosstalk between TAMs and cancer stem cells (CSCs) in HCC. Mouse macrophage cell line RAW264.7 cells were used to investigate the effects of TAMs on mouse hepatoma cell line Hepa1-6 cells in vivo and vitro. A total of 90 clinical samples had pathology-proven HCC were used to evaluate the distribution of TAMs and CSCs and analyze their value in predicting the prognosis. In the study, we have found that the number of TAMs has a positive correlation with the density of CSCs in the marginal of human HCC. Our results show that, cocultured with TAM-conditioned medium (CM) promoted CSC-like properties in Hepa1-6 cells, which underwent EMT and gained higher invasive capability. TAMs secreted more transforming growth factor- beta1 (TGF-beta1) than other phenotypes of macrophage. Furthermore, depletion of TGF-beta1 blocked acquisition of CSC-like properties by inhibition of TGF-beta1-induced EMT. High expression of CD68 in the EpCAM positive expression HCC tissues was strongly associated with both poor cancer-free survival and overall survival in patients. Our results indicate that the TAMs promote CSC-like properties via TGF-beta1-induced EMT and they may contribute to investigate the prognosis of HCC.

Hepatic stellate cells secreted hepatocyte growth factor contributes to the chemoresistance of hepatocellular carcinoma.

As the main source of extracellular matrix proteins in tumor stroma, hepatic stellate cells (HSCs) have a great impact on biological behaviors of hepatocellular carcinoma (HCC). In the present study, we have investigated a mechanism whereby HSCs modulate the chemoresistance of hepatoma cells. We used human HSC line lx-2 and chemotherapeutic agent cisplatin to investigate their effects on human HCC cell line Hep3B. The results showed that cisplatin resistance in Hep3B cells was enhanced with LX-2 CM (cultured medium) exposure in vitro as well as co-injection with LX-2 cells in null mice. Meanwhile, in presence of LX-2 CM, Hep3B cells underwent epithelial to mesenchymal transition (EMT) and upregulation of cancer stem cell (CSC) -like properties. Besides, LX-2 cells synthesized and secreted hepatic growth factor (HGF) into the CM. HGF receptor tyrosine kinase mesenchymal-epithelial transition factor (Met) was activated in Hep3B cells after LX-2 CM exposure. The HGF level of LX-2 CM could be effectively reduced by using HGF neutralizing antibody. Furthermore, depletion of HGF in LX-2 CM abolished its effects on activation of Met as well as promotion of the EMT, CSC-like features and cisplatin resistance in Hep3B cells. Collectively, secreting HGF into tumor milieu, HSCs may decrease hepatoma cells sensitization to chemotherapeutic agents by promoting EMT and CSC-like features via HGF/Met signaling.

Negative correlation of LIV-1 and E-cadherin expression in hepatocellular carcinoma cells.

LIV-1, a zinc transporter, is a mediator downstream of STAT3 both in zebrafish and mammalian cells, and is involved in epithelial-mesenchymal transition (EMT). Despite LIV-1 participates in cancer growth and metastasis, little is known about the association of LIV-1 with human liver cancer development. Therefore, the expression of LIV-1 mRNA was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) in 4 cultured cell lines (3 carcinoma and 1 normal liver cell lines), and the localization of LIV-1 protein was investigated by immunohistochemistry. Expression of LIV-1 protein was analyzed by Western blot both in 4 cultured cell lines and 120 liver tissues (100 carcinoma and 20 histologically normal tissues), and the relationship between its expression and clinicopathological finding was investigated in 100 hepatocellular carcinoma(HCC) tissues. Then stable siRNA expressing Hep-G2 cells were generated to assess the function of LIV-1 in liver cancer cells. We found that LIV-1 mRNA was more highly expressed in liver cancer cell lines compared to normal liver cell line. Western blot showed the expression of LIV-1 was higher in 61% liver carcinoma tissues than that in normal liver tissues. Down-regulated LIV-1 cells showed significant inhibition of proliferation in vitro and reduction of tumor growth in vivo. Furthermore, E-cadherin expression increased in LIV-1 siRNA expressing Hep-G2. These findings indicated that LIV-1 may induce the EMT in HCC cells.