Feng-Jun Xiao

Hepatocyte Growth Factor Gene-Modified Mesenchymal Stem Cells Reduce Radiation-Induced Lung Injury

Abstract Effective therapeutic strategies for radiation-induced lung injury (RILI) are lacking. Mesenchymal stem cells (MSCs), as gene therapy delivery vehicles, possess the ability to repair injured lung. In this study, we conducted MSC-based hepatocyte growth factor (HGF) gene therapy for RILI. Mice received single-dose radiation with 20 Gy of γ rays locally to the lung, and then were administered normal sodium, Ad-HGF-modified MSCs, or Ad-Null-modified MSCs. Ad-HGF-modified MSCs (MSCs-HGF) improved histopathological and biochemical markers of lung injury. MSCs-HGF could reduce secretion and expression of proinflammatory cytokines, including tumor necrosis factor-α, interferon-γ, interleukin (IL)-6, and intercellular adhesion molecule-1, and increase the expression of antiinflammatory cytokine IL-10. It could also decrease expression levels of profibrosis factors transforming growth factor-β, Col1a1 (collagen type 1, α1), and Col3a1, and inhibit fibrosis progress. MSCs-HGF could promote proliferation of lung epithelial cells and protect them from apoptosis, and improve the expression of endogenous HGF and its receptor c-Met significantly. We also found that sphingosine-1-phosphate receptor-1 expression was increased in injured lung. These results suggest MSC-based HGF gene therapy not only reduces inflammation but also inhibits lung fibrosis.

Beclin1 inhibition promotes autophagy and decreases gemcitabine–induced apoptosis in Miapaca2 pancreatic cancer cells

BackgroundBeclin1 is a well-known key regulator of autophagy, which is also a haploinsufficient tumor suppressor. Current studies revealed that down-regulation or monoallelic deletions of Beclin1 were frequently found in various cancers. The purpose of this study was to investigate the effects of Beclin1 inhibition on autophagy and Gemcitabine-induced apoptosis of pancreatic cancer cells.MethodsBeclin1 expression was inhibited by siRNA transduction and gene expression was determined by Real-time PCR and Western blot. The effects of Beclin1 inhibition on autophagy and Gemcitabine-induced apoptosis of Miapaca2 cells were analyed through LC3 expression, cell viability, cell cycle and apoptosis by using Western blot.ResultsWe observed that Beclin1 silence promoted microtubule-associated protein 1 light chain 3-II (LC3-II) protein formation and increased punctate fluorescent signals in Miapaca2 cells transfected with green fluorescent protein (GFP)-tagged LC3. Beclin1 inhibition showed a greater suppressive effect on Gemcitabine-induced apoptosis of Miapaca2 cells.ConclusionOur data suggested that Beclin1 silence not only up-adjusted autophagy process, but also played an important role in the regulation of apoptosis. Beclin1 inhibition could inhibit apoptosis signaling induced by Gemcitabine in Miapaca2 cells.

Surface Phosphatidylserine Is Responsible for the Internalization on Microvesicles Derived from Hypoxia-Induced Human Bone Marrow Mesenchymal Stem Cells into Human Endothelial Cells

Background Previous data have proven that microvesicles derived from hypoxia-induced mesenchymal stem cells (MSC-MVs) can be internalized into endothelial cells, enhancing their proliferation and vessel structure formation and promoting in vivo angiogenesis. However, there is a paucity of information about how the MSC-MVs are up-taken by endothelial cells. Methods MVs were prepared from the supernatants of human bone marrow MSCs that had been exposed to a hypoxic and/or serum-deprivation condition. The incorporation of hypoxia-induced MSC-MVs into human umbilical cord endothelial cells (HUVECs) was observed by flow cytometry and confocal microscopy in the presence or absence of recombinant human Annexin-V (Anx-V) and antibodies against human CD29 and CD44. Further, small interfering RNA (siRNA) targeted at Anx-V and PSR was delivered into HUVECs, or HUVECs were treated with a monoclonal antibody against phosphatidylserine receptor (PSR) and the cellular internalization of MVs was re-assessed. Results The addition of exogenous Anx-V could inhibit the uptake of MVs isolated from hypoxia-induced stem cells by HUVECs in a dose- and time-dependent manner, while the anti-CD29 and CD44 antibodies had no effect on the internalization process. The suppression was neither observed in Anx-V siRNA-transfected HUVECs, however, addition of anti-PSR antibody and PSR siRNA-transfected HUVECs greatly blocked the incorporation of MVs isolated from hypoxia-induced stem cells into HUVECs. Conclusion PS on the MVs isolated from hypoxia-induced stem cells is the critical molecule in the uptake by HUVECs.

MiRNA-486 regulates angiogenic activity and survival of mesenchymal stem cells under hypoxia through modulating Akt signal.

MicroRNA-486 (miR-486) was first identified from human fetal liver cDNA library and validated as a regulator of hematopoiesis. Its roles in regulating the biological function of bone marrow-derived mesnechymal stem cells (BM-MSCs) under hypoxia have not been explored yet. In this study, we demonstrated that exposure to hypoxia upregulates miR-486 expression in BM-MSCs. Lentivirus-mediated overexpression of miR-486 resulted in increase of hepatocyte growth factor (HGF) and vascular endothelial growth factor(VEGF) in both mRNA and protein levels. MiR-486 expression also promotes proliferation and reduces apoptosis of BM-MSCs. Whereas MiR-486 knockdown downregulated the secretion of HGF and VEGF and induced apoptosis of BM-MSCs. Furthermore, PTEN-PI3K/AKT signaling was validated to be involved in changes of BM-MSC biological functions regulated by miR-486. These results suggested that MiR-486 mediated the hypoxia-induced angiogenic activity and promoted the proliferation and survival of BM-MSCs through regulating PTEN-PI3K/AKT signaling. These findings might provide a novel understanding of effective therapeutic strategy for hypoxic-ischemic diseases.

SENP1 inhibition induces apoptosis and growth arrest of multiple myeloma cells through modulation of NF-κB signaling

SUMO/sentrin specific protease 1 (Senp1) is an important regulation protease in the protein sumoylation, which affects the cell cycle, proliferation and differentiation. The role of Senp1 mediated protein desumoylation in pathophysiological progression of multiple myeloma is unknown. In this study, we demonstrated that Senp1 is overexpressed and induced by IL-6 in multiple myeloma cells. Lentivirus-mediated Senp1 knockdown triggers apoptosis and reduces viability, proliferation and colony forming ability of MM cells. The NF-κB family members including P65 and inhibitor protein IkBα play important roles in regulation of MM cell survival and proliferation. We further demonstrated that Senp1 inhibition decreased IL-6-induced P65 and IkBα phosphorylation, leading to inactivation of NF-кB signaling in MM cells. These results delineate a key role for Senp1in IL-6 induced proliferation and survival of MM cells, suggesting it may be a potential new therapeutic target in MM.

SENP1 regulates hepatocyte growth factor-induced migration and epithelial-mesenchymal transition of hepatocellular carcinoma

The deregulation of HGF/c-Met signaling is implicated in epithelial-mesenchymal transition (EMT) and progress of hepatocellular carcinoma (HCC). However, the epigenetic mechanisms that HGF/c-Met regulates EMT and metastasis of HCC cells are less explored. In this study, we demonstrated that HCC cells express a high level of SUMO/sentrin-specific protease 1 (Senp1) which is induced by HGF/c-Met signals. Lentivirus-mediated small hairpin RNA (shRNA) transduction results in Senp1 silence in HCC cells. Senp1 silence reduces the HGF-induced proliferation and migration of HCC cells. Senp1 inhibition also induces HCC cell apoptosis and growth arrest. Furthermore, Senp1 knockdown inhibits epithelial-to-mesenchymal transition, with increase of E-cadherin and ZO-1 expression, decrease of fibronectin and N-cadherin expression. The EMT-related transcription factor Zeb1 was SUMO-modified and decreased in Senp1-silenced HCC cells. These results delineate that senp1 might play an important role in the regulation of HGF-induced invasion and migration of HCC cells.

miR‐486 regulates metastasis and chemosensitivity in hepatocellular carcinoma by targeting CLDN10 and CITRON

miRNA‐486 (miR‐486) was first identified from the human fetal liver cDNA library and considered to be associated with hepatocellular carcinoma (HCC) development. Its roles in regulation of HCC metastasis and chemosensitivity have not been explored yet.

Bortezomib and sphingosine kinase inhibitor interact synergistically to induces apoptosis in BCR/ABl+ cells sensitive and resistant to STI571 through down-regulation Mcl-1

Interactions between the proteasome inhibitor, bortezomib, and the sphingosine kinase (SPK1) inhibitor, SKI, were examined in BCR/ABL human leukemia cells. Coexposure of K562 or chronic myeloid leukemia (CML) cells from patients to subtoxic concentrations of SKI (10 μM) and bortezomib (100 nM) resulted in a synergistic increase in caspase-3 cleavage and apoptosis. These events were associated with the downregulation of BCR-ABL and Mcl-1, and a marked reduction in SPK1 expression. In imatinib mesylate-resistant K562 cells that displayed decreased BCR-ABL expression, bortezomib/SKI treatment markedly increased apoptosis and inhibited colony-formation in association with the downregulation of Mcl-1. Finally, the bortezomib/SKI regimen also potently induced the downregulation of BCR/ABL and Mcl-1 in human leukemia cells. Collectively, these findings suggest that combining SKI and bortezomib may represent a novel strategy in leukemia, including apoptosis-resistant BCR-ABL(+) hematologic malignancies.

Effects of Adenovirus-Mediated Delivery of the Human Hepatocyte Growth Factor Gene in Experimental Radiation-Induced Heart Disease

PURPOSE Irradiation to the heart may lead to late cardiovascular complications. The purpose of this study was to investigate whether adenovirus-mediated delivery of the human hepatocyte growth factor gene could reduce post-irradiation damage of the rat heart and improve heart function. METHODS AND MATERIALS Twenty rats received single-dose irradiation of 20 Gy gamma ray locally to the heart and were randomized into two groups. Two weeks after irradiation, these two groups of rats received Ad-HGF or mock adenovirus vector intramyocardial injection, respectively. Another 10 rats served as sham-irradiated controls. At post-irradiation Day 120, myocardial perfusion was tested by myocardial contrast echocardiography with contrast agent injected intravenously. At post-irradiation Day 180, cardiac function was assessed using the Langendorff technique with an isolated working heart model, after which heart samples were collected for histological evaluation. RESULTS Myocardial blood flow was significantly improved in HGF-treated animals as measured by myocardial contrast echocardiography at post-irradiation Day 120 . At post-irradiation Day 180, cardiac function was significantly improved in the HGF group compared with mock vector group, as measured by left ventricular peak systolic pressure (58.80 +/- 9.01 vs. 41.94 +/- 6.65 mm Hg, p < 0.05), the maximum dP/dt (5634 +/- 1303 vs. 1667 +/- 304 mm Hg/s, p < 0.01), and the minimum dP/dt (3477 +/- 1084 vs. 1566 +/- 499 mm Hg/s, p < 0.05). Picrosirius red staining analysis also revealed a significant reduction of fibrosis in the HGF group. CONCLUSION Based on the study findings, hepatocyte growth factor gene transfer can attenuate radiation-induced cardiac injury and can preserve cardiac function.

Endocrine glands-derived vascular endothelial growth factor protects pancreatic cancer cells from apoptosis via upregulation of the myeloid cell leukemia-1 protein.

Endocrine glands-derived vascular endothelial growth factor (EG-VEGF, also termed as Prok1)--a novel cytokine that selectively acts on the endothelial cells of endocrine glands--was recently reported to be involved in the regulation of tumor cell growth and survival. However, its roles in the regulation of pancreatic cancer progression remain unclear. In this report, we investigated the suppressive effects of EG-VEGF on pancreatic cancer cell apoptosis and the relevant mechanisms. By using reverse-transcriptase polymerase chain reaction (RT-PCR) we found that the Mia PaCa II cells of the pancreatic cancer cell line express the mRNAs of both EG-VEGF (Prok1) and its receptors. EG-VEGF protects pancreatic cancer cells from apoptosis through upregulation of myeloid cell leukemia-1 (Mcl-1), an anti-apoptotic protein of the bcl-2 family. Treatment of pancreatic cancer cells with EG-VEGF results in the rapid phosphorylation of mitogen-activated protein kinase (MAPK), STAT3, and AKT, which are involved in the upregulation of Mcl-1 expression. EG-VEGF (Prok1) protects Mia PaCa II cells from apoptosis through G protein-coupled receptor (GPR)-induced activation of multiple signal pathways, and hence can be a novel target for pancreatic cancer therapy.