Eunsung Jun

The DPC4/SMAD4 genetic status determines recurrence patterns and treatment outcomes in resected pancreatic ductal adenocarcinoma: A prospective cohort study

Objectives The objective of this study was to investigate the role of genetic status of DPC4 in recurrence patterns of resected pancreatic ductal adenocarcinoma (PDAC). Methods Between April 2004 and December 2011, data on patients undergoing surgical resection for PDAC were reviewed. Genetic status of DPC4 was determined and correlated to recurrence patterns and clinical outcomes. Results Analysis of 641 patients revealed that genetic status of DPC4 was associated with overall survival and was highly correlated with recurrence patterns, as inactivation of the DPC4 gene was the strongest predictor of metastatic recurrence (odds ratio = 4.28). Treatment modalities for recurrent PDAC included chemotherapy alone and concurrent chemotherapy along with local control. For both locoregional and metastatic recurrence, local control resulted in improved survival; however, for groups subdivided according to recurrence patterns and genetic status of DPC4, local control contributed to improved survival in locoregional recurrences of patients with expressed DPC4, while chemotherapy alone was sufficient for others. Conclusions Genetic status of DPC4 contributes to the recurrence patterns following pancreatectomy, and patients with an initially expressed DPC4 gene receive a greater benefit from intensive local control for locoregional recurrence. The DPC4 gene, therefore, may aid the establishment of treatment strategies for initial adjuvant treatment or for recurrent PDAC.

Diagnostic value of chromogranin A in pancreatic neuroendocrine tumors depends on tumor size: A prospective observational study from a single institute

Background. Chromogranin A has recently been recommended as the most practical tumor marker in patients with pancreatic neuroendocrine tumors. However, the diagnostic effectiveness of circulating chromogranin A levels remains controversial. Here, we aimed to assess the clinical diagnostic value of plasma chromogranin A levels for pancreatic neuroendocrine tumors. Methods. Between June 2012 and June 2015, 110 consecutive patients with a suspected pancreatic neuroendocrine tumor were prospectively enrolled. We evaluated the diagnostic value of the chromogranin A assay for differentiating pancreatic neuroendocrine tumors from other tumors. The plasma chromogranin A levels in the pancreatic neuroendocrine tumor patients were examined according to various clinicopathologic factors. Results. A total of 65 patients were diagnosed as having pancreatic neuroendocrine tumors, whereas 45 had other tumors. The median chromogranin A level in pancreatic neuroendocrine tumor cases was higher than that in cases of other tumors (pancreatic neuroendocrine tumors: 126.62 ng/mL, other tumors: 69.82 ng/mL). The sensitivity, specificity, and accuracy of the chromogranin A assay for pancreatic neuroendocrine tumor diagnosis were 49.2%, 77.8%, and 60.9%, respectively. The chromogranin A levels after operative resection were reduced or were confirmed as being within the normal range (78.9%) in most cases. Moreover, the chromogranin A level in pancreatic neuroendocrine tumors cases was correlated with tumor size based on comparisons with other tumors in the pancreas (P = .038). The sensitivity, specificity, and accuracy of the chromogranin A assay for large tumors were greater, at 64.3%, 100.0%, and 81.5%, respectively. Conclusion. In clinical settings, the identification of pancreatic neuroendocrine tumors is vital for the development of therapeutic strategies. In large pancreatic tumors, the measurement of chromogranin A levels is very useful for distinguishing pancreatic neuroendocrine tumors from other tumors in the pancreas.

Locally-applied 5-fluorouracil-loaded slow-release patch prevents pancreatic cancer growth in an orthotopic mouse model

To obtain improved efficacy against pancreatic cancer, we investigated the efficacy and safety of a locally-applied 5-fluorouracil (5-FU)-loaded polymeric patch on pancreatic tumors in an orthotopic nude-mouse model. The 5-FU-releasing polymeric patch was produced by 3D printing. After application of the patch, it released the drug slowly for 4 weeks, and suppressed BxPC-3 pancreas cancer growth. Luciferase imaging of BxPC3-Luc cells implanted in the pancreas was performed longitudinally. The drug patch delivered a 30.2 times higher level of 5-FU than an intra-peritoneal (i.p.) bolus injection on day-1. High 5-FU levels were accumulated within one week by the patch. Four groups were compared for efficacy of 5-FU. Drug-free patch as a negative control (Group I); 30% 5-FU-loaded patch (4.8 mg) (Group II); 5-FU i.p. once (4.8 mg) (Group III); 5-FU i.p. once a week (1.2 mg), three times (Group IV). The tumor growth rate was significantly faster in Group I than Group II, III, IV (p=0.047 at day-8, p=0.022 at day-12, p=0.002 at day-18 and p=0.034 at day-21). All mice in Group III died of drug toxicity within two weeks after injection. Group II showed more effective suppression of tumor growth than Group IV (p=0.018 at day-12 and p=0.017 at day-21). Histological analysis showed extensive apoptosis in the TUNEL assay and by Ki -67 staining. Western blotting confirmed strong expression of cleaved caspase-3 in Group II. No significant changes were found hematologically and histologically in the liver, kidney and spleen in Groups I, II, IV but were found in Group III.

Enhanced insulin production and reprogramming efficiency of mesenchymal stem cells derived from porcine pancreas using suitable induction medium

Genetic reprogramming is a powerful method for altering cell properties and inducing differentiation. However, even if the same gene is reprogrammed, the results vary among cells. Therefore, a better possible strategy involves treating cells with factors that further stimulate differentiation while using stem cells with the same tissue origin. This study aimed to increase induction efficiency and insulin production in reprogrammed cells using a combination of factors that promote cell differentiation.

Method Optimization for Extracting High-Quality RNA From the Human Pancreas Tissue

Nucleic acid sequencing is frequently used to determine the molecular basis of diseases. Therefore, proper storage of biological specimens is essential to inhibit nucleic acid degradation. RNA isolated from the human pancreas is generally of poor quality because of its high concentration of endogenous RNase. In this study, we optimized the method for extracting high quality RNA from paired tumor and normal pancreatic tissues obtained from eight pancreatic cancer patients post-surgery. RNA integrity number (RIN) was checked to evaluate the integrity of RNA, we tried to extract the RNA with an RIN value of 8 or higher that allows for the latest genetic analysis. The effect of several parameters, including the method used for tissue lysis, RNAlater treatment, tissue weight at storage, and the time to storage after surgical resection, on the quantity and quality of RNA extracted was examined. Data showed that the highest quantity of RNA was isolated using a combination of manual and mechanical methods of tissue lysis. Additionally, sectioning the tissues into small pieces (<100 mg) and treating them with RNAlater solution prior to storage increased RNA stability. Following these guidelines, high quality RNA was obtained from 100% (8/8) of tumor tissues and 75% (6/8) of normal tissues. High-quality RNA was still stable under repeated freezing and thawing. The application of these results during sample handling and storage in clinical settings will facilitate the genetic diagnosis of diseases and their subsequent treatment.

Synergistic effect of a drug loaded electrospun patch and systemic chemotherapy in pancreatic cancer xenograft

Pancreatic cancer has a high rate of local recurrence and poor prognosis even with adjuvant chemotherapy after curative resection. The aim of this study was to investigate if local drug delivery combined with low dose systemic chemotherapy can increase the therapeutic effect of chemotherapy while reducing systemic toxicities. Poly-L-lactic acid-based 5-FU releasing patch was fabricated by electrospinning, and its tumour killing effects were first confirmed in vitro. The 5-FU patch directly adhered to the tumour in subcutaneous and orthotopic murine models, and induced a significant decrease in tumour size. Systemic gemcitabine treatment group, 5-FU drug releasing patch group, and systemic gemcitabine plus 5-FU patch group were compared by tumour size measurement, non-invasive bio-imaging, and histology in subcutaneous models. Combination of local drug patch and systemic chemotherapy led to increased tumour suppression effects that lasted longer, as well as increased survival rate. Histology revealed higher degree of apoptosis in the combined group. Systemic toxicity was recovered within 7 days after the treatment in all mice. Conclusively, local drug delivery using biocompatible polymer patch significantly inhibited tumour growth, and combination with systemic chemotherapy was more effective than single systemic chemotherapy.

Genetic and metabolic comparison of orthotopic and heterotopic patient-derived pancreatic-cancer xenografts to the original patient tumors

Tumors from 25 patients with pancreatic cancer were used to establish two patient-derived xenograft (PDX) models: orthotopic PDX (PDOX) and heterotopic (subcutaneous) PDX (PDHX). We compared gene expression by immunohistochemistry, single-nucleotide polymorphism (SNP), DNA methylation, and metabolite levels. The 4 cases, of the total of 13 in which simultaneous PDHX & PDOX models were established, were randomly selected. The molecular-genetic characteristics of the patients tumor were well maintained in the two PDX models. SNP analysis demonstrated that both groups were more than 90% identical to the original patients tumor, and there was little difference between the two models. DNA methylation of most genes was similar among the two models and the original patients tumor, but some gene sets were hypermethylated the in PDOX model and hypomethylated in the PDHX model. Most of the metabolites had a similar pattern to those of the original patient tumor in both PDX tumor models, but some metabolites were more prominent in the PDOX and PDHX models. This is the first simultaneous molecular-genetic and metabolite comparison of patient tumors and their tumors established in PDOX and PDHX models. The results indicate high fidelity of these critical properties of the patient tumors in the two models.

Large-scale analysis for treatment strategy according to genetic alterations of KRAS and DPC4 (SMAD4) genes in pancreatic ductal adenocarcinoma.

361 Background: To investigate correlation of genetic alterations of pancreatic ductal adenocarcinoma (PDAC) with patients’ survival, recurrence patterns, and treatment for recurrent disease. Methods: We reviewed genetic alterations of major 4 genes (K-ras, DPC4, p53, and c-erbB-2) in 699 patients who underwent surgical resection, and correlated with clinical outcomes. Results: Median survival of all patients was 21.7 months, and 5-year survival rate was 20.4%. Alterational rates of each gene were as follows: K-ras, 48.3%; DPC4, 68.1%; p53, 40.8%; c-erbB-2, 14.0%. Mutation of K-ras and inactivation of DPC4 genes were associated with shorter patients’ survival in univariate analysis. In multivariate analysis, mutation of K-ras gene was independently correlated with patients’ survival (especially, GAT and TGT subtypes). Inactivated DPC4 gene had no independent correlation with overall survival, but it was strongly associated with distant metastasis following pancreatectomy. Survival after recurrence (SAR) w...