Qiuping Xie

HUMAN BONE MARROW MESENCHYMAL STEM CELLS DIFFERENTIATE INTO INSULIN-PRODUCING CELLS UPON MICROENVIRONMENTAL MANIPULATION IN VITRO

It was recently reported that pluripotent mesenchymal stem cells (MSCs) in rodent bone marrow (BM) have the capacity to generate insulin-producing cells (IPCs) in vitro. However, little is known about this capacity in human BM-MSCs. We developed a nongenetic method to induce human BM-MSCs to transdifferentiate into IPCs both phenotypically and functionally. BM-MSCs from 12 human donors were sequentially cultured in specially defined conditions. Their differentiation extent toward beta-cell phenotype was evaluated systemically. Specifically, after induction human BM-MSCs formed spheroid islet-like clusters containing IPCs, which was further confirmed by dithizone (DTZ) staining and electron microscopy. These IPCs expressed multiple genes related to the development or function of pancreatic beta cells (including NKX6.1, ISL-1, Beta2/Neurod, Glut2, Pax6, nestin, PDX-1, ngn3, insulin and glucagon). The coexpression of insulin and c-peptide was observed in IPCs by immunofluorescence. Moreover, they were able to release insulin in a glucose-dependent manner and ameliorate the diabetic conditions of streptozotocin (STZ)-treated nude mice. These results indicate that human BM-MSCs might be an available candidate to overcome limitations of islet transplantation.

Anthocyanins from Chinese Bayberry Extract Protect β Cells from Oxidative Stress-Mediated Injury via HO-1 Upregulation

Oxidative stress plays a pivotal role during the islet transplantation procedure, and antioxidant supplementation may protect grafts against oxidative injury. Chinese bayberry is one of six Myrica species native to China, and we demonstrated here that anthocyanins from Chinese bayberry extract (CBE) protect pancreatic β cells (INS-1) against hydrogen peroxide (H(2)O(2))-induced necrosis and apoptosis. Anthocyanins time- and dose-dependently upregulated heme oxygenase-1 (HO-1) gene expression in β cells and primary islets. HO-1 knockdown increased H(2)O(2)-induced cell death and attenuated the cytoprotective effect of anthocyanins. Anthocyanin treatment activated ERK1/2 and PI3K/Akt signaling, and ERK1/2 and PI3K inhibitors partially attenuated anthocyanin-mediated induction of HO-1. Additionally, β cells pretreated with anthocyanins displayed a decreased extent of apoptosis after transplantation. In summary, these results suggest that anthocyanins in CBE protect β cells from H(2)O(2)-induced cell injury via ERK1/2- and PI3K/Akt-mediated HO-1 upregulation.

Carbon nanotube-based magnetic-fluorescent nanohybrids as highly efficient contrast agents for multimodal cellular imaging

We developed a simple and novel layer-by-layer (LBL) assembly in combination with covalent connection strategy for the synthesis of multifunctional carbon nanotubes (CNTs)-based magnetic-fluorescent nanohybrids as multimodal cellular imaging agents for detecting human embryonic kidney (HEK) 293T cells via magnetic resonance (MRI) and confocal fluorescence imaging. Superparamagnetic iron oxide nanoparticles (SPIO) and near-infrared fluorescent CdTe quantum dots (QDs) were covalently coupled on the surface of CNTs in sequence via LBL assembly. It was indicated that the SPIO layer acted not only as a contrast agent for MRI, but also as a spacer between CdTe QDs and CNTs for prohibiting fluorescence quenching of QDs on the surface of the CNTs. The multifunctional CNT-based magnetic-fluorescent nanohybrids showed an enhanced MRI signal as contrast agent for detecting 293T cells in comparison with the pure SPIO. This is due to the magnetic coupling between the orderly arrayed SPIO, the function of CNTs for lowering the transverse relaxation and the ability of CNTs for penetrating into cells. Moreover, the multifunctional CNT-based magnetic-fluorescent nanohybrids exhibited the higher intracellular labeling efficiency due to the ability of CNTs for penetrating into cells in comparison with pure SPIO-CdTe nanoparticles.

Elevated levels of plasma fibrinogen in patients with pancreatic cancer: possible role of a distant metastasis predictor.

Objectives: Although changes of plasma fibrinogen have been documented in limited pancreatic malignant tumors, a relationship between plasma fibrinogen and pancreatic cancer in a large-scale clinical study has not been shown. Methods: Preoperative plasma levels of fibrinogen were retrospectively analyzed in 133 pancreatic cancer and 38 pancreatic benign tumor patients. Results: Plasma fibrinogen in pancreatic cancer patients were significantly higher than those with benign pancreatic tumor (3.99 ± 1.01 vs 2.62 ± 0.65; P < 0.001). The percentage of hyperfibrinogenemia (>4.20 g/L) in pancreatic cancer was 41.1%, and no positive results were obtained in benign pancreatic disease. Plasma fibrinogen levels were increased in pancreatic cancer with advanced tumor stage. Accompanied with the progression of tumor stage, there was an increase in the percentage of positivity of hyperfibrinogenemia in pancreatic cancer. There were markedly higher levels of plasma fibrinogen in the distant-metastasis group than in the no-distant-metastasis group (4.41 ± 0.84 vs 3.76 ± 1.04; P < 0.01). Univariate and multivariate analysis revealed that high plasma fibrinogen levels (>4.20 g/L) were positively associated with distant metastasis of pancreatic cancer. Conclusions: Plasma fibrinogen levels had a positive relationship with tumor stage of pancreatic cancer. Increased preoperative plasma fibrinogen levels might be a useful predictor for distant metastasis in human pancreatic cancer.

Potentiation of the effect of gemcitabine by emodin in pancreatic cancer is associated with survivin inhibition.

Pancreatic cancer is one human malignancy which has chemoresistant behavior to gemcitabine treatment. In this study, we revealed that emodin, an active component from Chinese medicinal herbs, could enhance pancreatic cancer cells apoptosis induced by gemcitabine. Survivin, a member of the inhibitor of apoptosis gene family, is involved in control of cell division and inhibition of apoptosis and described as a beta-catenin/Tcf/Lef target gene. Western blot and PCR analysis showed that emodin suppressed survivin expression in a dose- and time-dependent manner. We further demonstrated survivin expression could be up-regulated by gemcitabine. Surprisingly, survivin expression induced by gemcitabine could be inhibited in combination with emodin treatment. Moreover, cells treated with gemcitabine and emodin showed a preferential peri-plasmamembrane position of beta-catenin, blocking the translocation of beta-catenin to nucleus induced by gemcitabine. In addition to these in vitro results, we also found that emodin potentiates the antitumor effects of gemcitabine in vivo by down-regulating the expression of survivin and beta-catenin. Taken together, these results suggest that emodin potentiates gemcitabine antitumor activity through suppression of survivin gene in pancreatic cancer.

Labeling transplanted mice islet with polyvinylpyrrolidone coated superparamagnetic iron oxide nanoparticles for in vivo detection by magnetic resonance imaging

Superparamagnetic iron oxide nanoparticles (SPIO) are emerging as a novel probe for noninvasive cell tracking with magnetic resonance imaging (MRI) and have potential wide usage in medical research. In this study, we have developed a method using high-temperature hydrolysis of chelate metal alkoxide complexes to synthesize polyvinylpyrrolidone coated iron oxide nanoparticles (PVP-SPIO), as a biocompatible magnetic agent that can efficiently label mice islet beta-cells. The size, crystal structure and magnetic properties of the as-synthesized nanoparticles have been characterized. The newly synthesized PVP-SPIO with high stability, crystallinity and saturation magnetization can be efficiently internalized into beta-cells, without affecting viability and function. The imaging of 100 PVP-SPIO-labeled mice islets in the syngeneic renal subcapsular model of transplantation under a clinical 3.0 T MR imager showed high spatial resolution in vivo. These results indicated the great potential application of the PVP-SPIO as an MRI contrast agent for monitoring transplanted islet grafts in the clinical management of diabetes in the near future.

Delta like ligand 4 induces impaired chemo-drug delivery and enhanced chemoresistance in pancreatic cancer.

The stubborn chemoresistance of pancreatic ductal adenocarcinoma (PDA) is simultaneously influenced by tumor parenchymal and stromal factors, and the ctritical role of Notch ligand Delta-like 4 (DLL4) in the regulation of tumor malignancies has been observed. DLL4 positive expression ratio between duct cells from clinical tumor and adjacent tissues was statistically significant, and the overactivation of DLL4/Notch pathway enhanced the phenotype of EMT and cancer stem cell, even can induce multi-chemoresistance in vitro. Notably, the accompanied defective angiogenesis directly induced inefficient chemo-drug delivery in vivo. Collectively, overexpressed DLL4 on neoplastic cells can enhance chemoresistance through angiogenesis-dependent/independent mechanisms in PDA.

DJ-1, a novel biomarker and a selected target gene for overcoming chemoresistance in pancreatic cancer.

PurposeAberrant expression of DJ-1 has been proven to be associated with tumorigenesis in many carcinomas. However, its role in pancreatic cancer is unknown. The aims of this study were to investigate whether the serum DJ-1 might be a potential biomarker for pancreatic cancer and to determine the biologic function of DJ-1 expression in gemcitabine-induced chemoresistance of pancreatic cancer.MethodsThe serum level of DJ-1 was higher in 128 pancreatic cancer patients compared with 62 healthy controls by ELISA. To determine the effect of DJ-1 on pancreatic tumor chemoresistance, a siRNA-targeting DJ-1 was synthesized and a stably transfected cell line with DJ-1 over-expression was constructed. The mechanism of tumor chemoresistance was assessed by multiple methods, such as MTT assay, real-time PCR, Western blot and flow cytometry.ResultsThe serum level of DJ-1 was higher in pancreatic cancer patients than healthy controls, and it has the relationship with tumor differentiation in pancreatic cancer. Down-regulation of DJ-1 enhanced gemcitabine-induced apoptosis in three pancreatic cancer cell lines. On the contrary, over-expression of DJ-1 desensitized the MIA PaCa-2 to the induction of apoptosis by gemcitabine.ConclusionsOur results suggest that the serum level of DJ-1 may be a potential biomarker for pancreatic cancer, and that DJ-1 plays critical roles in the pancreatic tumor chemoresistance, supporting the development of chemotherapeutic approaches targeting this oncogene.

Detection of viability of transplanted beta cells labeled with a novel contrast agent – polyvinylpyrrolidone-coated superparamagnetic iron oxide nanoparticles by magnetic resonance imaging

Islets can be visualized on MRI by labeling with superparamagnetic contrast agent during the transplantation procedure. However, whether the signal intensity reflects the cell number and cellular viability has not been determined. We used a self-synthesized novel superparamagnetic contrast agent -polyvinylpyrrolidone-coated superparamagnetic iron oxide nanoparticles (PVP-SPIO) - to label β-TC-6 cells (a mouse insulinoma cell line) or primary islets with commercial Feridex as a control. The labeling efficiency of two agents was compared by Prussian blue staining, intracellular iron content determination and MR scanning. Cells were exposed to hypoxia, high-glucose or exogenous H₂O₂ stimulation before/after PVP-SPIO labeling. Normal and injured cells were also transplanted into renal subcapsule. A clinically used 3.0 T MR scan was performed in vitro and 24 h post-transplantation to investigate the correlation between cellular viability and signal. Our PVP-SPIO displayed superior biocompatibility and magnetic properties. All of the cells could be labeled at 100 µg/ml iron concentration after 24 h incubation. At 100 µg/ml iron concentration, 1 × 10⁵ β cells labeled with PVP-SPIO could already be visualized in vitro by MRI, less than the detection threshold of Feridex. There existed a linear correlation between the number of labeled cells and R₂ value on the T₂ -weighted images. The signal intensity and the intracellular iron content declined along with the decreased viability of labeled cells. There was also a significant difference in signal intensity between injured and normal labeled cells after transplantation. From these results, we concluded that PVP-SPIO possessed superior cell labeling efficiency, and β cells could be labeled without compromising viability and function. The signal intensity on MRI might be a useful predictor to evaluate the number and the viability of PVP-SPIO-labeled cells.

MACC1 upregulation promotes gastric cancer tumor cell metastasis and predicts a poor prognosis.

In various studies, metastasis associated with colon cancer 1 (MACC1) has been frequently reported to be abnormally highly expressed in human lung cancer, colon cancer, and hepatocellular carcinoma. Our study focuses on the association of MACC1 expression with gastric cancer (GC). During our experiment, the MACC1 expression was tested in 105 GC samples using an immunohistochemical (IHC) method. The clinical characteristics and prognosis of these patients were summarized. During analysis, MACC1 distribution in GC samples with distant metastasis was higher than that in normal samples and in tumors with no dissemination. Subsequently, a lower 5-year survival rate had a strong correlation with high MACC1 expression. As a consequence, the present results suggest that MACC1 is more frequently expressed in a poor prognosis phenotype of GC and acts as a promising prognostic prediction parameter for GC.中文概要目的评估MACC1 基因在胃癌发生发展中的作用。创新点首次发现胃癌中MACC1 基因高表达,并且在患 者标本中发现高表达MACC1 和胃癌的远处转移 和预后有显著相关性。方法使用免疫组化的方法对105 例胃癌患者进行分析, 并且将MACC1 和其临床特点包括年龄、肿瘤大 小、肿瘤分化以及远处转移状况进行归纳和显著 性检验,进一步将患者分为MACC1 高表达和低 表达组。通过定期的随访,绘制患者生存曲线。结论本实验中发现了在胃癌远处转移灶组织中 MACC1 表达显著升高。然而MACC1 的高表达 和胃癌的肿瘤大小、肿瘤分化等特性未见明显相 关性。同时胃癌患者的5 年生存率和MACC1 的 高表达有显著性关联。