Qi-Han Fu

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.

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.

Inhibition of Protein Phosphatase 2A Enhances Cytotoxicity and Accessibility of Chemotherapeutic Drugs to Hepatocellular Carcinomas

Hepatocellular carcinoma (HCC) is one of the most common and therapeutically challenging malignancies worldwide. For patients ineligible for “curative resection” or liver transplantation, chemotherapy is an important minimally effective option. Strategies for chemosensitization are urgently needed. Here, we report that LB-100, a serine/threonine protein phosphatase 2A (PP2A) inhibitor, enhances the cytotoxicity of chemotherapy for HCC in vitro and in vivo. We found that LB-100 significantly enhanced inhibition of HCC by doxorubicin and cisplatin in vitro and in vivo in a PP2A-dependent way, while having little inhibitory activity when used alone. LB-100 promoted vascular endothelial growth factor secretion and vasculogenic mimicry, associated with increased microvessel density and blood perfusion of tumor cell xenografts. LB-100 also enhanced paracellular endothelial permeability to Evans Blue dye and doxorubicin in vivo and in vitro, presumably by altering vascular endothelial–cadherin contact between cells. Changes in permeability and perfusion were accompanied by increased accumulation of doxorubicin in HCC xenografts but not in normal liver tissue. In conclusion, LB-100 enhances chemotherapy by interfering with DNA damage–induced defense mechanisms and by increasing angiogenesis and drug penetration into tumor cells. The induction of angiogenesis and vascular permeability of tumor xenografts by inhibition of PP2A may be a novel approach for enhancing the cytotoxic treatment of HCC and potentially other cancers. Mol Cancer Ther; 13(8); 2062–72. ©2014 AACR.

Hypoxia-inducible factor-2α promotes tumor progression and has crosstalk with Wnt/β-catenin signaling in pancreatic cancer

BackgroundPancreatic cancer is a devastating disease that is characterized by persistent hypoxia. The roles of hypoxia-inducible factor-2α (hif-2α) are different to those of hif-1α, although both are critical for tumor cells to adapt to the hypoxic microenvironment. However, unlike the well-studied hif-1α, the role of hif-2α in tumors, including pancreatic cancer, is poorly understood.MethodsHerein, we used a mutated hif-2α (A530T) to figure out the problem that wild-type hif-2α is quickly degraded which limits the study of its function. Using several cell lines, mouse models, and human tissues, we obtained a general picture of hif-2α in pancreatic cancer progression.ResultsFunctional assays revealed that hif-2α promotes epithelial-to-mesenchymal transition, enhances tumor proliferation and invasion, increases stemness, facilitates angiogenesis, and up-regulates aerobic glycolysis. We identified an interaction between hif-2α and β-catenin, and found that hif-2α/β-catenin complex formation increased the activity of β-catenin and the protein stability of hif-2α. In vivo study confirmed the pro-oncogenic role of hif-2α, whose expression correlated with those of E-cadherin, vimentin, Ki-67, and CD31, but not hif-1α. A human tissue study showed that hif-2α was associated with lymph node metastasis, pathological grade, stroma abundance, vascularization and patient survival. High expression of hif-2α was also identified as an independent indicator of poor prognosis in patients with pancreatic cancer.ConclusionsOur systematic study revealed the roles of hif-2α in pancreatic cancer, and may provide a novel target for this highly malignant disease.

Hypoxia‐inducible factor‐1α/interleukin‐1β signaling enhances hepatoma epithelial–mesenchymal transition through macrophages in a hypoxic‐inflammatory microenvironment

The development and progression of hepatocellular carcinoma (HCC) are dependent on its local microenvironment. Hypoxia and inflammation are two critical factors that shape the HCC microenvironment; however, the interplay between the two factors and the involvement of cancer cells under such conditions remain poorly understood. We found that tumor‐associated macrophages, the primary proinflammatory cells within tumors, secreted more interleukin 1β (IL‐1β) under moderate hypoxic conditions due to increased stability of hypoxia inducible factor 1α (HIF‐1α). Under persistent and severe hypoxia, we found that the necrotic debris of HCC cells induced potent IL‐1β release by tumor‐associated macrophages with an M2 phenotype. We further confirmed that the necrotic debris–induced IL‐1β secretion was mediated through Toll‐like receptor 4/TIR domain–containing adapter‐inducing interferon‐β/nuclear factor kappa‐light‐chain‐enhancer of activated B cells signaling in a similar, but not identical, fashion to lipopolysaccharide‐induced inflammation. Using mass spectrometry, we identified a group of proteins with O‐linked glycosylation to be responsible for the necrotic debris–induced IL‐1β secretion. Following the increase of IL‐1β in the local microenvironment, the synthesis of HIF‐1α was up‐regulated by IL‐1β in HCC cells through cyclooxygenase‐2. The epithelial–mesenchymal transition of HCC cells was enhanced by overexpression of HIF‐1α. We further showed that IL‐1β promoted HCC metastasis in mouse models and was predictive of poor prognosis in HCC patients. Conclusion: Our findings revealed an HIF‐1α/IL‐1β signaling loop between cancer cells and tumor‐associated macrophages in a hypoxic microenvironment, resulting in cancer cell epithelial–mesenchymal transition and metastasis; more importantly, our results suggest a potential role of an anti‐inflammatory strategy in HCC treatment. (Hepatology 2018;67:1872‐1889)

Sister Mary Joseph's nodule as a first sign of pancreatic cancer

Sister Mary Josephs nodule (SMJN) refers to a metastatic tumor of the umbilicus. It is a rare entity which arises from a malignancy in the intra-abdominal cavity. We herein describe a patient who presented with SMJN as his first sign of pancreatic cancer. It is an even more unusual case of SMJN. We therefore, suggest that pancreatic cancer should be included in the differential diagnosis when an umbilical mass is found. With the progress made in surgical procedures and other modalities, an early diagnosis will dramatically improve the prognosis of the patients.

LB-100 sensitizes hepatocellular carcinoma cells to the effects of sorafenib during hypoxia by activation of Smad3 phosphorylation

Hepatocellular carcinoma (HCC) is a common cancer with poor prognosis. The multikinase inhibitor sorafenib is the only clinically proved systematic treatment for HCC. However, few patients respond to sorafenib. Hypoxic microenvironments contribute to sorafenib resistance. LB-100, a serine/threonine protein phosphatase 2A (PP2A) inhibitor was previously found to be a chemosensitizer in HCC. Here, we tested whether LB-100 could sensitize HCC to the effects of sorafenib. Intriguingly, LB-100 enhanced the effects of sorafenib in HCC cells only during hypoxic environments. LB-100 dramatically increased intracellular p-Smad3 level, which was responsible for the effect of LB-100 as a sensitizer. LB-100 downregulated Bcl-2 expression and enhanced sorafenib-induced apoptosis in HCC cells. We further proved that PP2A mediated LB-100-induced p-Smad3 overexpression. In addition, p38 mitogen-activated protein kinase pathway was activated in hypoxic conditions, and enhanced p-Smad3-dependent Bcl-2 inhibition and consequent apoptosis. In conclusion, LB-100 sensitized HCC cells to sorafenib in hypoxic environments. This effect was mediated by inactivation of PP2A, resulting in enhanced level of p-Smad3. Increased p-Smad3 downregulated Bcl-2, causing increased apoptosis of HCC cells.

Hook1 inhibits malignancy and epithelial-mesenchymal transition in hepatocellular carcinoma.

Hook1 is a member of the hook family of coiled-coil proteins, which is recently found to be associated with malignant tumors. However, its biological function in hepatocellular carcinoma is yet unknown. Here, we evaluated the Hook1 levels in human hepatocellular carcinoma samples and matched peritumoral tissues by real-time polymerase chain reaction. Small interfering RNA knockdown and a transforming growth factor-β-induced epithelial–mesenchymal transition model were employed to investigate the biological effects of Hook1 in hepatocellular carcinoma. Our results indicated that Hook1 levels were significantly lower in hepatocellular carcinoma tissues than in the peritumoral tissues. In addition, Hook1 expression was significantly associated with hepatocellular carcinoma malignancy. Hook1 was downregulated after transforming growth factor-β-induced epithelial–mesenchymal transition. Moreover, Hook1 knockdown promoted epithelial–mesenchymal transition and attenuated the sensitivity of hepatocellular carcinoma cells to doxorubicin. In summary, our results indicate that downregulation of Hook1 plays a pivotal role in hepatocellular carcinoma progression via epithelial–mesenchymal transition. Hook1 may be used as a novel marker and therapeutic molecular target in hepatocellular carcinoma.

Primary tumor-derived exosomes facilitate metastasis by regulating adhesion of circulating tumor cells via SMAD3 in liver cancer

Hepatocellular carcinoma (HCC) is a fatal disease and patients with HCC frequently die from metastasis. The mechanisms of HCC metastasis are not completely understood. In the present study, in vitro and in vivo data showed that HCC cells promoted cancer cell proliferation and lung metastases formation in a paracrinal/endocrinal way. We found that HCC-derived exosomes mediated this phenomenon and observed enhanced cell adhesion in the presence of these malignant exosomes. We further identified that reactive oxygen species (ROS) regulated the adhesive molecules. Intriguingly, attached HCC cells released exosomes containing both SMAD Family Member 3 (SMAD3) protein and mRNA, which were delivered to detached HCC cells and facilitated their adhesion. These exosomes induced enhanced SMAD3 signaling in the recipient HCC cells and increased their adhesive ability. In addition, we showed that SMAD3-abundant exosomes existed in the peripheral blood of patients with HCC, and their levels correlated with disease stage and the SMAD3 expression of primary tumors. Our study suggested a possible mechanism by which primary HCC supported metastases formation and revealed the role of SMAD3 in the exosomes-mediated crosstalk between primary and circulating HCC cells.