Xueli Bai

Wnt/β-catenin signaling enhances hypoxia-induced epithelial-mesenchymal transition in hepatocellular carcinoma via crosstalk with hif-1α signaling.

Epithelial-mesenchymal transition (EMT) is a critical process for tumor invasion and metastasis. Hypoxia may induce EMT, and upregulated β-catenin expression has been found in various tumors. In this study, we investigate the role of β-catenin in hypoxia-induced EMT in hepatocellular carcinoma (HCC). Induction of EMT in HCC cell lines by hypoxia was confirmed by altered morphology, expression change of EMT-associated markers and enhanced invasion capacity. We showed that hypoxia-induced EMT could be enhanced by addition of recombinant Wnt3a while it was repressed by β-catenin small interfering RNA. An interaction between β-catenin and hypoxia-induced factor-1α (hif-1α) was found, and an underlying competition for β-catenin between hif-1α and T-cell factor-4 was implied. Notably, increased hif-1α activity was accompanied with more significant EMT features. We also showed that the pro-EMT effect of β-catenin in hypoxia was deprived in the absence of hif-1α. Moreover, β-catenin was found to be responsible for the maintenance of viability and proliferation for tumor cells undergoing hypoxia. We further showed a correlation between hif-1α and β-catenin expression, and corresponding expression of EMT-associated markers in human HCC tissues. Our results suggest that Wnt/β-catenin signaling enhances hypoxia-induced EMT in HCC by increasing the EMT-associated activity of hif-1α and preventing tumor cell death.

Macrophage-induced tumor angiogenesis is regulated by the TSC2-mTOR pathway

Tumor-associated macrophages (TAM) have multifaceted roles in tumor development but they have been associated particularly closely with tumor angiogenesis. However, although the accumulation of TAM (M2 phenotype) promotes tumor angiogenesis, the mechanism through which monocytes differentiate to generate TAM is unclear. Here, we report that the mTOR pathway is a critical element in the regulation of monocyte differentiation to TAM. In human peripheral monocytes stimulated by lipopolysaccharide, mTOR was inhibited by rapamycin or activated by RNA interference-mediated knockdown of the mTOR repressor tuberous sclerosis complex 2 (TSC2). Rapamycin caused the monocytes to differentiate into M1 macrophages releasing more interleukin (IL)-12 and less IL-10, whereas TSC2 knockdown caused the monocytes to differentiate into M2 macrophages releasing less IL-12 and more IL-10. In parallel fashion, angiogenic properties were promoted or reduced in human umbilical vein endothelial cells cocultured with TSC2-deficient monocytes or rapamycin-treated monocytes, respectively. Furthermore, tumor angiogenesis and growth in murine xenografts were promoted or reduced by infusion of hosts with TSC2-deficient or TSC2-overexpressing monocytes, respectively. Finally, in vivo depletion of macrophages was sufficient to block the antiangiogenic effects of rapamycin on tumors. Our results define the TSC2-mTOR pathway as a key determinant in the differentiation of monocytes into M2 phenotype TAM that promote angiogenesis.

Hypoxia-Induced Epithelial-to-Mesenchymal Transition in Hepatocellular Carcinoma Induces an Immunosuppressive Tumor Microenvironment to Promote Metastasis

Portal vein tumor thrombosis (PVTT) is a significant risk factor for metastasis in hepatocellular carcinoma (HCC) patients and is therefore associated with poor prognosis. The presence of PVTT frequently accompanies substantial hypoxia within the tumor microenvironment, which is suggested to accelerate tumor metastasis, but it is unclear how this occurs. Recent evidence has shown that the hypoxia-inducible factor HIF-1α induces epithelial-to-mesenchymal transition (EMT) in tumor cells to facilitate metastasis. In this study, we investigated whether hypoxia-induced EMT in cancer cells also affects immune cells in the tumor microenvironment to promote immunosuppression. We found that hypoxia-induced EMT increased the expression of the CCL20 cytokine in hepatoma cells. Furthermore, coculture of monocyte-derived macrophages with hypoxic hepatoma cells revealed that the expression of indoleamine 2, 3-dioxygenase (IDO) was induced in monocyte-derived macrophages in a CCL20-dependent manner. In turn, these IDO-expressing monocyte-derived macrophages suppressed T-cell proliferation and promoted the expansion of immunosuppressive regulatory T cells. Moreover, high CCL20 expression in HCC specimens was associated with PVTT and poor patient survival. Collectively, our findings suggest that the HIF-1α/CCL20/IDO axis in hepatocellular carcinoma is important for accelerating tumor metastasis through both the induction of EMT and the establishment of an immunosuppressive tumor microenvironment, warranting further investigation into the therapeutic effects of blocking specific nodes of this signaling network.

Therapeutic potential and related signal pathway of adipose-derived stem cell transplantation for rat liver injury

Aim:  Liver transplantation is the only currently effective therapy for end‐stage chronic liver disease and severe acute liver failure, but its use is limited by high cost and a shortage of allografts. Here we explored the effectiveness of transplanting adipose‐derived stem cells (ADSCs) into rats with experimentally induced liver injury.

Intraoperative blood salvage during liver transplantation in patients with hepatocellular carcinoma: efficiency of leukocyte depletion filters in the removal of tumor cells.

Background. Intraoperative blood salvage (IBS) reduces homologous transfusion in orthotopic liver transplantation (OLT), but may carry with it the risk of reinfusing tumor cells in patients with hepatocellular carcinoma (HCC). The use of leukocyte depletion filters (LDFs) for the removal of tumor cells is rarely reported in clinical OLT. The aims of this study were to evaluate the frequency of tumor cell contamination in surgical field during OLT for HCC recipients and to investigate the efficiency of additional LDFs for eliminating tumor cells from IBS. Methods. Thirty-two HCC patients with preoperatively elevated serum alpha-fetoprotein (AFP) underwent OLT. The blood from the surgical field was collected and processed by an autotransfusion device (Cell Saver 5), followed by 2 consecutive LDF filtrations. The HCC cells in IBS samples and filtered samples were determined using a nested RT-PCR technique to detect the AFP mRNA. Results. The shed blood samples from 20 (62.5%) of the 32 HCC patients were contaminated with HCC cells and 15 of them remained positive after Cell Saver processing. Patients within the Milan or UCSF criteria were less likely to have HCC cell contamination and the contaminated HCC cells were more likely to be removed by the Cell Saver in these patients as compared to other patients (P<0.01). After filtration through an additional LDF, most cases (13/15) became negative except for those with ruptured tumors (P<0.05). Conclusions. Our results suggest that blood filtration with the LDF can efficiently remove tumor cells and the use of an additional LDF after use of the Cell Saver could markedly reduce the risk of tumor cell reintroduction during the OLT in HCC recipients with nonruptured tumors.

Pancreatic Fistula after Pancreaticoduodenectomy: Diagnosed according to International Study Group Pancreatic Fistula (ISGPF) Definition

Aims: The aim of the study is to validate a new classification of pancreatic fistula (PF) and to document risk factors for PF. Methods: A retrospective study was performed on 100 patients who underwent pancreaticoduodenectomy (PD) within a 2-year period. PF was diagnosed according to the criteria developed by an International Study Group on Pancreatic Fistula (ISGPF). Sixteen pre- and intraoperative risk factors for PF were analyzed. Results: Of 100 patients 32 developed PF; grade A in 21 patients, grade B in 10, and grade C in 1.Four risk factors including pathological diagnosis, concomitant surgery, diameter of pancreatic duct, and texture of the remnant pancreas were found to be significantly associated with PF by univariate analysis. Texture of the remnant pancreas and concomitant surgery were demonstrated to be independent risk factors by multivariate logistic regression. If a PF occurred, advanced age was found to be a risk factor for PF grade B by univariate analysis, but age was not an independent risk factor by multivariate logistic regression. Conclusions: The status of the remnant pancreas is identified asa substantial risk factor for PF after PD. When soft remnant pancreas is encountered, more careful handling is required in an attempt to minimize the rate of PF. This study confirms that the ISGPF classification of PF is useful.

Myocyte enhancer factor 2C regulation of hepatocellular carcinoma via vascular endothelial growth factor and Wnt/β-catenin signaling

Hepatocellular carcinoma (HCC) is one of the leading malignancies worldwide. Myocyte enhancer factor 2C (MEF2C) was traditionally regarded as a development-associated factor and was recently reported to be an oncogene candidate. We have previously reported overexpression of MEF2C in HCC; however, the roles of MEF2C in HCC remain to be clarified. In this study, HCC cell lines and a xenograft mouse model were used to determine the functions of MEF2C in vitro and in vivo, respectively. Specific plasmids and small interfering RNA were used to upregulate and downregulate MEF2C expression, respectively. Functional assays were performed to assess the influence of MEF2C on cell proliferation, and VEGF-induced vasculogenic mimicry, migration/invasion as well as angiogenesis. Co-immunoprecipitation was conducted to identify the interaction of MEF2C and β-catenin. Human HCC tissue microarrays were used to investigate correlations among MEF2C, β-catenin and involved biomarkers. MEF2C was found to mediate VEGF-induced vasculogenic mimicry, angiogenesis and migration/invasion, with involvement of the p38 MAPK and PKC signaling pathways. However, MEF2C itself inhibited tumor growth in vitro and in vivo. MEF2C was upregulated by and directly interacted with β-catenin. The nuclear translocation of β-catenin blocked by MEF2C was responsible for MEF2C-mediated growth inhibition. The nuclear translocation of MEF2C was associated with intracellular calcium signaling induced by β-catenin. HCC microarrays showed correlations of nuclear MEF2C with the angiogenesis-associated biomarker, CD31, and cytosolic MEF2C with the proliferation-associated biomarker, Ki-67. MEF2C showed double-edged activities in HCC, namely mediating VEGF-induced malignancy enhancement while inhibiting cancer proliferation via blockade of Wnt/β-catenin signaling. The overall effect of MEF2C in HCC progression regulation was dictated by its subcellular distribution. This should be determined prior to any MEF2C-associated intervention in HCC.

Serotonin promotes the proliferation of serum- deprived hepatocellular carcinoma cells via upregulation of FOXO3a

BackgroundPeripheral serotonin is involved in tumorigenesis and induces a pro-proliferative effect in hepatocellular carcinoma (HCC) cells; however, the intracellular mechanisms by which serotonin exerts a mitogenic effect remain unclear. In this research, we examined whether FOXO3a, a transcription factor at the interface of crucial cellular processes, plays a role downstream of serotonin in HCC cells.ResultsThe cell viability and expression of FOXO3a was assessed in three HCC cell lines (Huh7, HepG2 and Hep3B) during serum deprivation in the presence or absence of serotonin. Serum free media significantly inhibited HCC proliferation and led to reduced expression and nuclear accumulation of FOXO3a. Knockdown of FOXO3a enhanced the ability of serum deprivation to inhibit HCC cells proliferation. And overexpression of non-phosphorylated FOXO3a in HCC cells reversed serum-deprivation-induced growth inhibition. Serotonin reversed the serum-deprivation-induced inhibition of cell proliferation and upregulated FOXO3a in Huh7 cells; however, serotonin had no effect on the proliferation of serum-deprived HepG2 or Hep3B cells. In addition to proliferation, serotonin also induced phosphorylation of AKT and FOXO3a in serum-deprived Huh7 cells but not in HepG2 and Hep3B cells. However, the phosphorylation of FOXO3a induced by serotonin did not export FOXO3a from nucleus to cytoplasm in serum-deprived Huh7 cells. Consequently, we demonstrated that serotonin promoted the proliferation of Huh7 cells by increasing the expression of FOXO3a. We also provide preliminary evidence that different expression levels of the 5-HT2B receptor (5-HT2BR) may contribute to the distinct effects of serotonin in different serum-deprived HCC cells.ConclusionsThis study demonstrates that FOXO3a functions as a growth factor in serum-deprived HCC cells and serotonin promotes the proliferation of serum-deprived HCC cells via upregulation of FOXO3a, in the presence of sufficient levels of the serotonin receptor 5-HT2BR. Drugs targeting the serotonin-5-HT2BR-FOXO3a pathway may provide a novel target for anticancer therapy.

NSC 74859-mediated inhibition of STAT3 enhances the anti-proliferative activity of cetuximab in hepatocellular carcinoma

Cetuximab [an epidermal growth factor receptor (EGFR) inhibitor], which was shown to be effective in rectal and non‐small cell lung cancers (NSCLCs), was only modestly effective in clinical trials of hepatocellular carcinoma (HCC). STAT3, which is thought to be a determinant of HCC sensitivity to antitumour drugs, may be involved.

Inhibition of protein phosphatase 2A sensitizes pancreatic cancer to chemotherapy by increasing drug perfusion via HIF-1α-VEGF mediated angiogenesis.

Pancreatic cancer is a malignant disease without efficient treatment. Improved treatments are urgently needed to enhance or replace chemotherapy. Here we used a small molecular compound LB-100 to assess the effect of pharmacological inhibition of protein phosphatase 2A (PP2A) in combination with doxorubicin on the proliferation of pancreatic cancer in cell lines and a xenograft model. LB-100 moderately reduced PP2A activity and the growth of the cell lines but did not show chemosensitization in vitro. In vivo, however, LB-100 synergistically enhanced the activity of doxorubicin. This effect was associated with increased microvessel density, blood perfusion, and doxorubicin concentrations within the xenografts. Mechanically, LB-100 induced expression of hypoxia-induced factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF). In an umbilical vein endothelial cell monolayer model for measuring changes in vascular permeability, increased VEGF secretion following exposure to LB-100 and doxorubicin was accompanied by increased amounts of doxorubicin penetrating the endothelial barrier. In conclusion, PP2A inhibition by LB-100 enhanced the cytotoxicity of doxorubicin in vivo but not in vitro potentially via HIF-1α-VEGF mediated angiogenesis. Combining inhibition of PP2A with chemotherapeutic regimens may enhance their effectiveness against pancreatic cancer.