Yongping Zhang

Metformin alters the expression profiles of microRNAs in human pancreatic cancer cells

AIMS To investigate the effect of metformin on the expression profiles of microRNAs in human pancreatic cancer cells. METHODS MicroRNAs real-time PCR Array was applied to investigate differentially expressed miRNAs in Sw1990 cells treated with or without metformin. Stem-loop real time RT-PCR was used to confirm the results of the array assay in Sw1990 and Panc-1 cells. The effects of miR-26a on cell growth, apoptosis, invasion and migration abilities were respectively examined by CCK8 assay, Apoptosis assay, Matrigel invasion and migration assay. HMGA1 was proved to be a target of miR-26a by Luciferase reporter assay, Real-time PCR and Western-blotting. RESULTS Nine miRNAs were significantly up-regulated in metformin treated cells. Metformin up-regulated the expression of miR-26a, miR-192 and let-7c in a dose-dependent manner. Forced expression of miR-26a significantly inhibited cell proliferation, invasion, migration and increased cell apoptosis, whereas knockdown of miR-26a obtained the opposite effect. Furthermore, we demonstrated that HMGA1, an oncogene, is a direct target of miR-26a. Nude mice xenograft models confirmed that metformin up-regulated the level of miR-26a and surpressed the expression of HMGA1 in vivo. CONCLUSION These observations suggested that modulation of miRNA expression may be an important mechanism underlying the biological effects of metformin.

XAF1 as a prognostic biomarker and therapeutic target in pancreatic cancer

XAF1 (X chromosome‐linked inhibitor of apoptosis [XIAP]‐associated factor 1) is a novel XIAP modulator that negatively regulates the anti‐apoptotic effects of XIAP and sensitizes cells to other cell death triggers. It has been reported to be downregulated in a variety of human cancer cell lines. However, the role of XAF1 in pancreatic carcinogenesis remains unclear. In the present study, we investigated the prognostic values of XAF1 expression and its regulation in cancer cell growth and apoptosis both in vitro and in vivo. From the immunohistochemistry staining of tissue microarray, 40 of 89 (44.9%) pancreatic specimens showed low levels of XAF1 expression. Statistical analysis suggested the downregulation of XAF1 was significantly correlated with tumor staging (P = 0.047) and those patients with low XAF1 levels had shorter survival times (P = 0.0162). Multivariate analysis indicated that XAF1 expression was an independent prognostic indicator of the survival of patients with pancreatic cancer (P = 0.007). Furthermore, we found that restoration of XAF1 expression mediated by Ad5/F35 virus suppressed cell proliferation and induced cell cycle arrest and apoptosis, accompanied by the activation of caspases 3, 8, and 9 and poly(ADP‐ribose) polymerase as well as increased level of cytochrome c and Bid cleavage. Notably, XAF1 restoration robustly decreased survivin expression rather than XIAP. In addition, in vivo s.c. xenografts from Ad5/F35‐XAF1 treatment, which showed less cellular proliferation and enhanced apoptosis, were significantly smaller than those from control groups. Our findings document that XAF1 is a valuable prognostic marker in pancreatic cancer and could be a potential candidate for cancer gene therapy. (Cancer Sci 2009)

Regulation and functional role of eEF1A2 in pancreatic carcinoma.

Pancreatic cancer typically has an unfavourable prognosis due to late diagnosis and a lack of therapeutic options. Thus, it is important to better understand its pathological mechanism and to develop more effective treatments for the disease. Human chromosome 20q13 has long been suspected to harbour oncogenes involved in pancreatic cancer and other tumours. In this study, we found that eEF1A2, a gene located in 20q13, was significantly upregulated in pancreatic cancer. Little or no expression of eEF1A2 was detected in normal human pancreatic and chronic pancreatitis tissues, whereas increased eEF1A2 expression occurred in 83% of the pancreatic cancers we studied. Furthermore, using in vitro and in vivo model systems, we found that overexpression of eEF1A2 promoted cell growth, survival, and invasion in pancreatic cancer. Our data thus suggest that eEF1A2 might play an important role in pancreatic carcinogenesis, possibly by acting as a tumour oncogene.

Activated protein C, an anticoagulant polypeptide, ameliorates severe acute pancreatitis via regulation of mitogen-activated protein kinases

BackgroundOur aim was to investigate the changes of mitogen-activated protein kinases (MAPKs) by activated protein C (APC) treatment in rats with severe acute pancreatitis (SAP), and relate them to changes in SAP severity, thus providing evidence for developing clinical therapies.MethodsSprague-Dawley rats were given an intravenous injection of saline (SAP group), APC (50 µg/kg or 10 µg/kg), or CNI1493 just before SAP induction. One group of rats underwent a sham operation (control group). Experimental samples were harvested 16 h after SAP induction. The gene expression of pancreatic MAPKs was evaluated by cDNA microarrays. The mRNA and protein/phosphorylated protein levels of p38 MAPK, extracellular signal-regulated protein kinase (ERK) 1/2, and c-Jun N-terminal kinase (JNK) and the protein levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β were determined in pancreatic tissue. The severity of disease was evaluated by pancreatic histology, the pancreatic wet/dry weight ratio, and the serum amylase level.ResultsIn rats treated with APC (50 µg/kg) or CNI1493, the severity of pancreatitis and expression of pancreatic TNF-α and IL-1β proteins were attenuated by the decreased expression and activity of p38 MAPK and JNK (vs. the SAP group, P < 0.01). The expression and activity of ERK1/2 were increased in APC-treated rats, especially in the group treated with APC 50 µg/kg (vs. the SAP or CNI1493-treated group, P < 0.01, respectively).ConclusionsInhibition of expression of pancreatic p38 MAPK and JNK and upregulation of ERK1/2 expression by APC treatment may protect against pancreatic injury, thus ameliorating severity of the disease.

Thymosin alpha 1 improves severe acute pancreatitis in rats via regulation of peripheral T cell number and cytokine serum level

Aim:  The aim of this study was to investigate the effect of thymosin alpha 1 (TA1) on severe acute pancreatitis (SAP) in rats.

High dose glargine alters the expression profiles of microRNAs in pancreatic cancer cells

AIM To investigate the effect of high dose glargine on the expression profiles of microRNAs in human pancreatic cancer cells. METHODS Real-time polymerase chain reaction array (RT-PCR) was applied to investigate miRNAs differentially expressed in Sw1990 cells treated with or without 100 IU/L glargine. Stem-loop RT-PCR was used to confirm the results of the array assay in Sw1990 and Panc-1 cells. The effects of miR-95 on cell growth, apoptosis, invasion and migration abilities were respectively examined by CCK8 assay, apoptosis assay, Matrigel invasion and migration assay in Sw1990 and Panc-1 cells. Nude mice xenograft models with Sw1990 cells were built to investigate pancreatic cancer growth in vivo after transfection by the lentivirus pGLV3-GFP- miR-95. RESULTS Ten miRNAs were significantly up-regulated and 2 miRNAs down-regulated in glargine treated Sw1990 cells when compared with non-treated cells (2.48-fold changes on average, P < 0.01). miR-95, miR-134 and miR-34c-3p are the top three miRNAs regulated by glargine (3.65-fold, 2.67-fold and 2.60-fold changes respectively, P < 0.01) in Sw1990 cells. Stem-loop RT-PCR confirmed that high dose glargine up-regulated the expression of miR-95 and miR-134 in both Sw1990 and Panc-1 cells. The most obvious change is the apparent increase of miR-95. Forced expression of miR-95 significantly increased cell proliferation (Sw1990: 2.510 ± 0.129 vs 2.305 ± 0.187, P < 0.05; Panc-1: 2.439 ± 0.211 vs 2.264 ± 0.117, P < 0.05), invasion (Sw1990: 67.90 ± 12.33 vs 47.30 ± 5.89, P < 0.01; Panc-1: 37.80 ± 8.93 vs 30.20 ± 5.14, P < 0.01), migration (Sw1990: 101 ± 6.00 vs 51.20 ± 8.34, P < 0.01; Panc-1: 91.80 ± 9.22 vs 81.50 ± 7.47, P < 0.01) and inhibited cell apoptosis (Sw1990: 22.05% ± 1.92% vs 40.32% ± 1.93%, P < 0.05; Panc-1: 20.17% ± 0.85% vs 45.60% ± 1.43%, P < 0.05) when compared with paired negative controls, whereas knockdown of miR-95 obtained the opposite effect. Nude mice xenograft models confirmed that miR-95 promoted the growth of pancreatic cancer in vivo when compared with negative control (tumor volume: 373.82 ± 23.67 mL vs 219.69 ± 17.82 mL, P < 0.05). CONCLUSION These observations suggested that modulation of miRNA expression may be an important mechanism underlying the biological effects of glargine.

Treatment of pancreatic carcinoma by adenoviral mediated gene transfer of vasostatin in mice

Background: Tumour growth is angiogenesis dependent and antiangiogenesis therapy may represent a promising therapeutic option. Aims: To evaluate the inhibitory effect of vasostatin gene mediated by a replication deficient recombinant adenovirus (Ad) on human pancreatic cancer in vivo and to investigate the mechanism of action of vasostatin. Methods: Human umbilical vein endothelium derived ECV304 cells were infected with Ad-vasostatin and Ad-lacZ, and compared with phosphate buffered saline (PBS). MTT (3,-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay was used to estimate the proliferation of ECV304 cells; tube formation assay and choriallantoic membrane assay were used to evaluate angiogenesis in vivo and in vitro. Xenografted nude mice with pancreatic cancer were established to observe in vivo tumour growth suppression. Microvessel density revealed by CD31 immunohistochemical staining was measured. Results: Growth and tube formation of ECV304 cells infected with Ad-vasostatin were suppressed significantly compared with cells infected with Ad-lacZ or cells treated with PBS. Neovascularisation in the Ad-vasostatin group was less than that in the PBS and Ad-lacZ groups, based on chorioallantoic membrane results. Volumes of pancreatic tumours in the Ad-vasostatin group were significantly smaller than those in the PBS and Ad-lacZ groups at the end of the treatment period. Microvessel density in the Ad-vasostatin group was significantly lower than that in the Ad-lacZ and PBS groups. Conclusion: The vasostatin gene mediated by adenovirus is efficient for gene therapy for pancreatic carcinoma. Suppression of vasostatin on proliferation of vascular endothelium cells and angiogenesis may account for its effect.

Fractalkine Upregulates Inflammation through CX3CR1 and the Jak–Stat Pathway in Severe Acute Pancreatitis Rat Model

Based on the function of chemokine fractalkine (FKN), acting as both adhesion and chemoattractant, FKN plays a role in acute inflammatory response. In this study, we investigated the mechanism of FKN mediated upregulation inflammation in severe acute pancreatitis (SAP) rat models. Western blot, reverse transcriptase-polymerase chain reaction, and immunofluorescence demonstrated that FKN and its receptor CX3CR1 were overexpressed in cerulein-stimulated AR42J cells. AG490 and FKN-siRNA inhibited activation of Janus kinase/signal transducers and activators of transcription (Jak/Stat) in cerulein-stimulated AR42J cells. Following exposure AG490 and FKN-siRNA inhibited tumor necrosis factor-alpha expression by enzyme-linked immunosorbent assay and immunohistochemistry in vivo the SAP rat models. These results showed FKN and CX3CR1 were involved inflammatory response in cerulein-stimulated AR42J cells. FKN upregulates inflammation through CX3CR1 and the Jak/Stat pathway in SAP rat models.

siRNA-based targeting of fractalkine overexpression suppresses inflammation development in a severe acute pancreatitis rat model.

Fractalkine (FKN), a chemokine that acts as both an adhesion molecule and a chemoattractant, is expressed in many inflammatory diseases. Chemokines play a crucial role in severe acute pancreatitis (SAP). This study used adenovirus-mediated siRNA to target FKN overexpression and assessed its ability to suppress inflammation development in a SAP rat model. Adenovirus-mediated FKN siRNA was transfected into cerulein-stimulated AR42J cells. The growth of cerulein-stimulated AR42J cells was determined by colony formation and MTT assays. The inhibitory effect of the FKN siRNA was studied in a SAP rat model in vivo and detected by ELISA, RT-PCR, western blot analysis and immunohistochemistry. FKN, IL-8 and TNF-α were found to be overexpressed in cerulein-stimulated AR42J cells by ELISA and western blot analysis (P<0.05). The animal experiments confirmed that FKN siRNA could inhibit inflammation development in SAP. The values of serum FKN, TNF-α and IL-8 levels were decreased after FKN siRNA treatment (P<0.05). Furthermore, western blotting and RT-PCR analysis showed that FKN protein and mRNA levels were decreased after injection with FKN siRNA (P<0.05). Immunohistochemistry also showed that inflammation was decreased after injection with FKN-siRNA in the SAP rat model. Treatment with siRNA can inhibit FKN overexpression and also suppresses inflammation development in a SAP rat model. More importantly, this study indicated that FKN, which is overexpressed in the SAP rat model, may serve as a novel and effective therapeutic target for SAP.

Serum metabolomics differentiating pancreatic cancer from new-onset diabetes

To establish a screening strategy for pancreatic cancer (PC) based on new-onset diabetic mellitus (NO-DM), serum metabolomics analysis and a search for the metabolic pathways associated with PC related DM were performed. Serum samples from patients with NO-DM (n = 30) and patients with pancreatic cancer and NO-DM were examined by liquid chromatography-mass spectrometry. Data were analyzed using principal components analysis (PCA) and orthogonal projection to latent structures (OPLS) of the most significant metabolites. The diagnostic model was constructed using logistic regression analysis. Metabolic pathways were analyzed using the web-based tool MetPA. PC patients with NO-DM were older and had a lower BMI and shorter duration of DM than those with NO-DM. The metabolomic profiles of patients with PC and NO-DM were significantly different from those of patients with NO-DM in the PCA and OPLS models. Sixty two differential metabolites were identified by the OPLS model. The logistic regression model using a panel of two metabolites including N_Succinyl_L_diaminopimelic_acid and PE (18:2) had high sensitivity (93.3%) and specificity (93.1%) for PC. The top three metabolic pathways associated with PC related DM were valine, leucine and isoleucine biosynthesis and degradation, primary bile acid biosynthesis, and sphingolipid metabolism. In conclusion, screening for PC based on NO-DM using serum metabolomics in combination with clinic characteristics and CA19-9 is a potential useful strategy. Several metabolic pathways differed between PC related DM and type 2 DM.