Qingqu Guo

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.

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.

Inhibition of autophagy promotes metastasis and glycolysis by inducing ROS in gastric cancer cells

Autophagy defect has been shown to be correlated with malignant phenotype and poor prognosis of human cancers, however, the detailed mechanisms remain obscure. In this study, we investigated the biological changes induced by autophagy inhibition in gastric cancer. We showed that inhibition of autophagy in gastric cancer cells promotes epithelial-mesenchymal transition (EMT) and metastasis, alters metabolic phenotype from mitochondrial oxidative phosphorylation to aerobic glycolysis and converts cell phenotype toward malignant, which maybe further contribute to chemoresistance and poor prognosis of gastric cancer. We also identified that the EMT and metabolism alterations induced by autophagy inhibition were dependent on ROS-NF-κB-HIF-1α pathway. More importantly, scavenging of ROS by the antioxidant N-acetylcysteine (NAC) attenuated activation of NF-κB and HIF-1α in autophagy-deficient gastric cancer cells, and autophagy inhibition induced metastasis and glycolysis were also diminished by NAC in vivo. Taken together, our findings suggested that autophagy defect promotes metastasis and glycolysis of gastric cancer, and antioxidants could be used to improve disease outcome for gastric cancer patients with autophagy defect.

Enhancing apoptosis and overcoming resistance of gemcitabine in pancreatic cancer with bortezomib: a role of death-associated protein kinase-related apoptosis-inducing protein kinase 1

Aims and Background To investigate the role of the apoptosis gene, DAP (death-associated protein) kinase-related apoptosis-inducing protein kinase 1 (DRAK1), which is involved in enhancing cell sensitivity and overcoming cell resistance to gemcitabine in pancreatic cancer cells by the proteasome inhibitor bortezomib. Methods Cultured human pancreatic cancer gemcitabine-sensitive cell lines (bxpc-3) and gemcitabine-resistant (panc-1) cell lines were divided into four groups: control, treatment with bortezomib, treatment with gemcitabine, and the two-drug combination. Expression of DRAK1 genes in each group was detected by using reverse transcription-polymerase chain reaction and western blot. Apoptosis in the pancreatic cancer cell lines was measured by flow cytometry. Results We found that the effects of growth inhibition and apoptosis of gemcitabine on both pancreatic cancer cell lines were enhanced by bortezomib. Treatment of panc-1 and bxpc-3 cells with bortezomib (100 nM) and gemcitabine (50 μg/ml and 0.05 μg/ml, respectively) induced an increase in the levels of DRAK1 mRNA compared with the control and single-agent treatment. Furthermore, immunblotting analysis in panc-1 but not bxpc-3 cells showed similar changes in the expression of DRAK1 protein produced by combination therapy. Conclusions Our results demonstrated that bortezomib enhanced cell sensitivity and overcame cell resistance to gemcitabine in pancreatic cancer cells, which may be attributed to DRAK1 induced by bortezomib and the combination with gemcitabine.

Changes in mitochondrial function during EMT induced by TGFβ-1 in pancreatic cancer

Mitochondrial dysfunction is linked to cancer. Differences in the number, morphology and function of mitochondria have been observed between normal cells and cancer cells. However, changes in mitochondrial function during epithelial-mesenchymal transition (EMT) in pancreatic cancer are less known. In the present study, the cultured human pancreatic cancer cell line Panc-1 was treated with transforming growth factor (TGF)β-1. Mitochondrial functions following TGFβ-1 exposure in pancreatic cancer were investigated. It was noticed that TGFβ-1 treatment induces morphologic changes and a shift from epithelial to mesenchymal phenotype in pancreatic cancer. Furthermore, increased mitochondrial mass was detected in pancreatic cancer following TGFβ-1 treatment. Besides, the production of reactive oxygen species in TGFβ-1-treated pancreatic cancer cells significantly increased compared with the control cells. Our results indicate that the phenomenon of EMT in pancreatic cancer has an association with mitochondrial dysfunction. Mitochondrial dysfunction may be a cause of EMT in pancreatic cancer, which leads to heterogeneity in pancreatic cancer, and may be a potential therapeutic target in the future.

VNN1, a potential biomarker for pancreatic cancer-associated new-onset diabetes, aggravates paraneoplastic islet dysfunction by increasing oxidative stress

In our previous clinical microarray analysis, we were the first to report on Vanin-1 (VNN1) as a novel clinically derived biomarker of pancreatic cancer-associated new-onset diabetes (PCAND). The functional mechanisms of VNN1 in the pathogenesis of PCAND, however, are not completely understood. In the present study, we further extend our previous clinical study to include laboratory research. The functions and mechanisms of neoplastic overexpressed VNN1 in PCAND have been explored using a co-culture model. Furthermore, the serum concentrations and discrimination power of downstream molecules of VNN1 were tested in a PCAND cohort. Pancreatic ductal adenocarcinoma (PDA) overexpressed VNN1 further aggravates paraneoplastic islet dysfunction; decreases in GSH/PPAR-γ concentrations and increases in ROS/cysteamine might be primary cause of this effect. Clinical serum analyses revealed that the expression profiles of these molecules were aberrant in the PCAND group. Our results further demonstrated that PCAND is a type of paraneoplastic diabetes. As the only clinically derived biomarker for PCAND screening available today, the biological role of VNN1 in triggering oxidative stress within the pancreatic microenvironment is important. The molecules downstream of VNN1 are also potential biomarkers for PCAND screening.

Analysis of a cytoskeleton-associated kinase PEAK1 and E-cadherin in gastric cancer

The expression of pseudopodium-enriched atypical kinase 1(PEAK1) has been studied in human cancers. However, their roles in gastric cancer are still unknown. In this study, gastric cancer tissue microarrays were constructed with 159 gastric cancer tissue samples, 150 non-neoplastic gastric epithelium specimens and 152 lymph node samples. Immunohistochemical staining for PEAK1 and E-cadherin was performed. Our study found negative expression of PEAK1 in 113 of 159 (71.1%) gastric cancers, in 46 of 150 (30.7%) non-neoplastic gastric epithelium tissues and in 69 of 94 (73.4%) metastatic lymph nodes. Negative expression of PEAK1 and E-cadherin associated with tumor grading, depth of invasion, lymph node metastases, pTNM stage and macroscopic type. Patients with either positive PEAK1 or E-cadherin expression had a significantly higher survival than those with negative expression. When combined, PEAK1(-)/E-cadherin(-) had a significantly poor prognosis than the rest of the patients. The expression of PEAK1 protein was positively correlated with E-cadherin in cancer tissues. Cox regression analyses showed that PEAK1, E-cadherin and PEAK1(-)/E-cadherin(-) were independent predictors of overall survival. In conclusion, our findings suggest that loss of PEAK1 may play an important role in carcinogenesis and development of gastric cancer through activating epithelial to mesenchymal transition.