Yongfeng Xu

RGD-conjugated albumin nanoparticles as a novel delivery vehicle in pancreatic cancer therapy

Integrin αvβ3 receptor is expressed on several types of cancer cells, including pancreatic cancer cells, and plays an important role in tumor growth and metastasis. The ability to target the integrin αvβ3 receptor on cancer cells increases the efficacy of targeted therapy and reduces the side effects. The aim of this study is to develop a novel arginine-glycine-aspartic acid (RGD) peptide-conjugated albumin nanoparticle to enhance the intracellular uptake of anticancer drug into the pancreatic cancer cells through receptor-mediated endocytosis. In cellular uptake studies, the fluorescent signal of RGD-conjugated BSANPs in BxPC3 cells was higher than that of BSANPs without RGD conjugation as determined by fluorescence spectrophotometer. We also found that BSANPs bound to BxPC3 cells in a time- and concentration-dependent manner. The uptake of RGD-conjugated BSANPs by pancreatic cancer cells was inhibited by an excess amount of free RGD peptide, indicating that the binding and/or uptake were mediated by the αvβ3 receptor. Furthermore, the nanoparticles were found to be located close to the nuclei by using laser scanning confocal microscopy. Besides, no significant in vitro cytotoxicity was observed as measured with MTT assay. Both in vitro and in vivo antitumor efficacy was improved by targeting gemcitabine-loaded nanoparticles to BxPC-3 cells using RGD peptides. Therefore, the RGD-conjugated BSANPs hold great potential as an effective drug delivery system to deliver therapeutic agents to pancreatic cancer.

Cavin-1 is essential for the tumor-promoting effect of caveolin-1 and enhances its prognostic potency in pancreatic cancer.

Caveolin-1 exhibits a stage-dependent, functional fluctuation during pancreatic cancer development, but the underlying mechanisms remain unclear. Here, we report that cavin-1, a structural protein of caveolae, modulates the oncogenic function of caveolin-1 and cooperates with caveolin-1 to enhance pancreatic cancer aggressiveness. Cavin-1 expression is associated with caveolin-1 in pancreatic cancer tissue samples and cell lines, and predicts the metastatic potential of pancreatic cancer. Interactome analyses further revealed the physical interaction of cavin-1 and caveolin-1 and their colocalization in pancreatic cancer cells. Cavin-1 stabilizes caveolin-1 expression or activity by inhibiting its internalization and subsequent lysosomal degradation. More in-depth functional experiments showed that caveolin-1-enhanced aggressiveness of pancreatic cancer cells is dependent on the presence of cavin-1. In contrast, cavin-1 depletion inhibited the invasion and metastasis of pancreatic cancer cells, which could not be restored by caveolin-1-rescue construct. Tissue microarray analyses in two independent clinic cohorts also supported the augment of cavin-1 on the prognostic potency of caveolin-1, and showed that combination of cavin-1 with caveolin-1 predicted worse survival in pancreatic cancer patients. Of note, the phenotypes because of cavin-1 could not be achieved by other cavins such as cavin-2, and the tumor-promoting role of cavin-1 in pancreatic cancer was found to be largely dependent on caveolin-1 expression, which highlights the critical role of cavin-1/caveoin-1 in pancreatic cancer progression, and suggests that the interruption of cavin-1/caveolin-1 interaction is a promising therapeutic strategy for pancreatic cancer.

miR-1247 is Correlated with Prognosis of Pancreatic Cancer and Inhibits Cell Proliferation by Targeting Neuropilins

Accumulating evidence indicates that microRNAs (miRNAs) have great potential as tumor biomarkers and therapeutic agents owing to their functions in tumorigenesis and cancer progression. Aberrant expression of miR-1247 has been found in several cancers and is predicted to play an important role in the pathological processes of pancreatic cancer by miRNA-regulated network analysis. We investigated the expression profile of miR-1247 in pancreatic cancer tissue microarray by in situ hybridization and found that miR-1247 was significantly down-regulated in pancreatic cancer tissues compared to matched benign tissues. High levels of miR-1247 expression were positively correlated with higher overall and recurrence free survival in pancreatic cancer patients, while negatively correlated with tumor grade. Using in vitro and in vivo models, we demonstrated that increased expression of miR-1247 inhibited proliferation, tumorigenicity, colony formation and triggered G0/G1 cell cycle arrest in pancreatic cancer cells. Moreover, we confirmed that neuropilin1 (NRP1) and neuropilin2 (NRP2) are direct targets of miR-1247 by western blot and luciferase reporter assay. Further studies indicated that low dose all trans retinoic acid (ATRA) can induce redifferentiation and restoration of miR-1247 in pancreatic cancer cells. These findings suggest that miR-1247, a novel tumor suppressor, can act as a potential biomarker and therapeutic agent for pancreatic cancer.

Up-Regulation of MBD1 Promotes Pancreatic Cancer Cell Epithelial-Mesenchymal Transition and Invasion by Epigenetic Down-Regulation of E-Cadherin

Methyl-CpG binding domain protein 1 (MBD1) has been implicated in transcriptional regulation, heterochromatin formation, genomic stability, cell-cycle progression and development. It is also predicted that MBD1 might be involved in tumor development and progression. However, whether and how MBD1 is involved in tumorigenesis, especially in pancreatic cancer (PC), is currently unknown. We found that MBD1 was significantly up-regulated in PC tissues compared with the surrounding normal tissues according to RT-PCR data. Tissue microarray (TMA) based immunohistochemical study from 58 surgically resected PC specimens indicated that higher MBD1 expression correlated with lymph node metastasis and poor survival in PC patients. Gain- and loss-of-function studies in vitro validated MBD1 as a potent oncogene promoting PC cell invasion as well as epithelial-mesenchymal transition (EMT). Mechanistically, MBD1 is associated with Twist and NAD-dependent deacetylase sirtuin-1 (SIRT1), thereby forming the Twist-MBD1-SIRT1 complex on the CDH1 promoter, which resulted in reduced E-cadherin transcription activity and increased cell EMT ability. Significantly, targeting MBD1 reversed the EMT phenotype of PC and restored sensitivity to chemotherapy. Taken together, the results of our study revealed a novel function of MBD1 in PC invasion and metastasis by providing a molecular mechanism underlying MBD1-promoted EMT. Thus MBD1 may serve as a potential therapeutic target for PC.

Management of a malignant case of solid pseudopapillary tumor of pancreas: A case report and literature review

Solid pseudopapillary tumor of the pancreas is a rare neoplasm with low malignant potential, which affects predominantly young females. Only approximately 10% to 15% cases of solid pseudopapillary tumors (SPTs) are malignant. We present the case of a 57-year-old woman who developed malignant SPT of the pancreas. Meanwhile, a literature review was carried out. Some clinicopathological features and strategies of management of malignant SPT are presented. In general, surgical removal of the tumor even in case of metastases or recurrence offers an excellent prognosis. Chemotherapy and radiotherapy should be taken into consideration in patients with unresectable tumor.

Profilin1 Sensitizes Pancreatic Cancer Cells to Irradiation by Inducing Apoptosis and Reducing Autophagy

Pancreatic cancer has an extremely poor prognosis mainly due to lack of effective treatment options. Radiotherapy is mostly applied to locally advanced cases, although tumor radioresistance limits the effectiveness. Profilin1, a novel tumor suppressor gene, was reported to be down-regulated in various cancers and associated with tumor progression. The objective of this study was to demonstrate how profilin1 affected pancreatic cancer radiosensitivity. We showed profilin1 was down-regulated in pancreatic cancer cells after exposure to radiation, and re-expression of profilin1 suppressed tumor cell viability and increased DNA damage following irradiation. Further studies revealed that up-regulation of profilin1 facilitated apoptosis and repressed autophagy induced by irradiation, which might sensitize pancreatic cancer cells to radiation treatment. Our findings may provide a novel therapeutic strategy for sensitizing pancreatic cancer to radiotherapy.

Stathmin, interacting with Nf-κB, promotes tumor growth and predicts poor prognosis of pancreatic cancer.

Stathmin (STMN) has been known as a p53-regulated protein and has been shown to play an oncogenic role in a range of human malignancies. Paradoxically, most recent studies demonstrated that stathmin has a dual function as both an oncogene and a metastasis suppressor. Stathmin is a member of microtubule dynamic destabilizing proteins and stathmin-regulated microtubule disruption could lead to a variety of cell dysfunctions such as enhanced chronic hypoxia in pancreatic cancer. In this study, we identified that stathmin promotes proliferation of pancreatic cancer cells by an underlying nuclear factor kappa B (Nf-κB) interacting mechanism. In human specimens, stathmin was significantly overexpressed in pancreatic cancer tissues and high expression of stathmin was correlated with vascular emboli (p=0.028), tumor size (p=0.019), and overall survival (p=0.031). Functional assays showed that knockdown of stathmin significantly reduced pancreatic cancer cell viability, colony formation, and arrested the cell cycle at the G2/M phase. Furthermore, silence of stathmin could reduce pancreatic tumor growth in nude mice. For the mechanism, Western blot analyses demonstrated that Nf-κB (p65) was significantly down-regulated when stathmin was silenced. In addition, co-immunoprecipitation (CoIP) assay suggested that stathmin was able to interact with Nf-κB (p65). Our findings indicate that stathmin might play its oncogenic role by an interaction with Nf-κB pathway, which may reveal a novel mechanism to uncover the role of microtubule-destabilizing stathmin in pancreatic cancer environment as well as provide a potential therapeutic strategy for pancreatic cancer.

Application of “Papillary-Like Main Pancreatic Duct Invaginated” Pancreaticojejunostomy for Normal Soft Pancreas Cases

Pancreaticojejunostomy is the key procedure of pancreaticoduodenectomy. Our study introduced a new pancreaticojejunal (PJ) anastomosis named “papillary-like main pancreatic duct invaginated” pancreaticojejunostomy. Nighty-two patients underwent pancreaticojejunostomy with either conventional duct-to-mucosa pancreaticojejunostomy or the new “papillary-like main pancreatic duct invaginated” techniques were analyzed retrospectively from January 2010 to September 2012. The incidence of pancreatic fistula was 15.7% (8/51) for the “papillary-like main pancreatic duct invaginated” group and 19.5% (8/41) for the duct-to-mucosa fashion respectively. It is noteworthy that the rate of grade B/C postoperative pancreatic fistula (POPF) in the “papillary-like main pancreatic duct invaginated” group was significantly lower than that of the duct-to-mucosa group (P = 0.039). There were no differences in the incidence of postoperative morbidity and mortality such as postoperative hemorrhage, delayed gastric emptying or remnant pancreatitis. The “papillary-like main pancreatic duct invaginated” pancreaticojejunostomy could provide a feasible option to pancreatic surgeons for patients with normal soft pancreas.

CD8+ T Cells Are Compromised In Human Pancreatic Cancer

Objectives and background: An efficient cellular immune response against cancer requires a robust population of CD8+ T cells with optimal cytotoxic functions. The aim of this study was to define the percentage of CD8+ T cells and the perforin expression level of the CD8+ T cells in the peripheral blood from patients with pancreatic adenocarcinoma. Methods: Fourty-six pancreatic cancer patients in our center between August 2011 and April 2012 were recruited. Thirty-five healthy persons were included as controls. Blood was drawn before surgery and one and a half months after surgery. Cells were labeled with monoclonal antibodies against perforin and surface antigen CD8 and were analyzed by flow cytometry. Results: Compared with the healthy controls, the percentage of CD8+ T cells was significantly decreased in pancreatic cancer patients. The level of perforin expression was also decreased in pancreatic cancer patients, whereas the percentage of CD8+ T cells was significantly increased after radical tumor resection. Conclusions: Both the number and function of CD8+ T cells were compromised in pancreatic cancer patients, which were partially recovered after the surgery.

High Expression of Human Leukocyte Antigen-G is Associated with a Poor Prognosis in Patients with PDAC.

Pancreatic Adenocarcinoma (PDAC) is one of the most deadly malignant tumors worldwide. A variety of mechanisms are involved in PDAC biological behaviors, of which, the mechanisms of immune escape may be a pivotal hallmark. HLA-G is a tolerant molecule implicated in tumor escape and serves as a prognostic biomarker in tumors. Our study evaluated the expression of HLA-G in PDAC and explored its clinical significance. In a cohort of 122 PDAC patients, 78 patents (63.9%) exhibited high level of HLA-G tumor tissues. Multivariate analysis suggested that HLA-G level was an independent predictor for OS (HR = 3.894, 95% CI = 2.380-6.370, p <0.001). High level of HLA-G significantly correlated with PDAC aggressive features, such as more advanced stage (TNM Stage II) (p<0.001), extrapancreatic infiltration (T3 stage) (p<0.001), lymph node involvement (p=0.019) and poor differentiation (p=0.010). In western blot analysis, almost all of the tumor cell lines (5/6) expressed high levels of HLA-G. In ELISA analysis, the level of plasma sHLA-G in PDAC patients were significantly increased than in healthy control (P=0.0037). Further analysis revealed the level of sHLA-G inversely related to numbers of peripheral activated T cells (CD8+CD28+ T cells), which may indicate that sHLA-G inactivates T cell responses resulting in tumor immune escape. In conclusion, tumor-derived HLA-G may indicate the mechanism of immune escape and impaired PDAC clinical outcome, especially in early-stage patients, which may also be a potential therapeutic target.