Masao Kawamoto

Nestin expression correlates with nerve and retroperitoneal tissue invasion in pancreatic cancer

Nestin was first described as an intermediate filament protein expressed in neuroepithelial stem cells. Nestin expression has also been reported in brain tumors, schwannomas, gastrointestinal stromal tumors, and melanomas. In the pancreas, Nestin expression has been detected in exocrine and mesenchymal cells, including stellate cells, pericytes, and endothelial cells. In the present study, we examined Nestin expression in human pancreatic ductal adenocarcinoma and sought to determine its role in this malignancy. Reverse transcription-polymerase chain reaction analysis demonstrated the presence of Nestin mRNA in all 10 tested pancreatic cancer cell lines, and quantitative reverse transcription-polymerase chain reaction revealed that Nestin mRNA levels were highest in PANC-1 cells and lowest in PK-8 cells. Immunofluorescent analysis revealed that Nestin localized in the outer cytoplasm of PANC-1 cells. Nestin immunoreactivity was present in the cancer cells in 20 (33.3%) of 60 cancer cases, and its expression was confirmed by in situ hybridization. Nestin expression was also increased in peripheral nerve fibers adjacent to cancer cells and in peripheral nerve fibers invaded by cancer cells. Clinicopathologically, there was a statistically significant association between Nestin expression in pancreatic cancer cells and nerve invasion (P = .010) and the presence of cancer cells in the tumor resection margins (P = .003). Nestin-positive cases exhibited similar survival after resection by comparison with Nestin-negative cases, irrespective of whether they were given adjuvant therapy. These findings indicate that Nestin expression in pancreatic cancer cells may contribute to nerve and stromal invasion in this malignancy.

Clinicopathologic study on pancreatic groove carcinoma.

Objectives: Pancreatic groove carcinoma usually presents with duodenal stenosis. This report describes the clinicopathologic features of 5 cases. Methods: All the clinical and radiological features were reviewed retrospectively and analyzed to identify correlations with the histological findings. Results: Vomiting was an initial symptom in all cases, but obstructive jaundice was not inevitable until the disease progresses. Hypotonic duodenography demonstrated severe postbulbar stenosis. Pathological findings of biopsy specimens showed no evidence of malignancy at the early stage. Computed tomography revealed a hypovascular mass. Magnetic resonance imaging indicated a hypointense mass on T1-weighted images and an isointense to slightly hyperintense mass on T2 images. Macroscopically, the stenosis seemed to be the result of a hard yellowish-white tumor invading the duodenal wall. Histopathologically, an adenocarcinoma arising from the groove infiltrated the submucosal layer of the duodenum circumferentially. No cancer cells were found in the mucosa at the early stage. The intrapancreatic common bile duct was involved at the advanced stage. Conclusions: We believe that these features resulted from the anatomical characteristics of the groove involvement and that the string stricture of the duodenum resulted from invasion of the groove tumor into the submucosal layer around the wall.

Multicentric pancreatic intraepithelial neoplasias (PanINs) presenting with the clinical features of chronic pancreatitis

A 46-year-old woman was readmitted to our hospital in August 2005 because of severe abdominal pain and nausea. Computed tomography demonstrated a huge cystic lesion in the retroperitoneal space behind the hepatoduodenal ligament and lesser peritoneal cavity. Endoscopic retrograde pancreatography revealed communication between the dilated main pancreatic duct and a pseudocyst. The condition was preoperatively diagnosed as chronic pancreatitis associated with a pseudocyst or an intraductal papillary mucinous neoplasm without mucin hypersecretion. The patient underwent a distal pancreatectomy with splenectomy. The pathologic diagnosis was multicentric pancreatic intraepithelial neoplasia (PanIN), and histological examination revealed a positive surgical margin around the remnant pancreas. Four months after the surgery, the patient underwent a total pancreatectomy. Macroscopic observation revealed diffuse fibrosis of the pancreatic parenchyma compatible with chronic pancreatitis. Histological examination revealed a constellation of noninvasive intraductal neoplasias with high-grade atypia, diffusely distributed in the small pancreatic ducts of the resected pancreas. Localized fibrosis and cystic dilation of the small ducts were detected in a lobule of exocrine glands draining into a ductule involved by PanIN lesions in the head of the pancreas. In summary, multicentric PanIN lesions are associated with lobular atrophy of the pancreatic parenchyma and chronic pancreatitis-like changes that follow. Total pancreatectomy may be recommended for patients with multicentric precursor lesions throughout the entire pancreas.

Improvement of Intraoperative Frozen Section Diagnosis in Patients with Biliary Strictures by Levovist Injection into the Bile Duct on Color Doppler Ultrasonography

BackgroundThis study evaluates the efficiency of color Doppler ultrasonography-guided intraoperative pancreatic biopsy (CDUS-IPB) using Levovist injected into the bile duct in conjunction with stimulated acoustic emission (SAE) in patients with biliary strictures.MethodsThe study was performed on 12 patients. After completing a conventional intraoperative pancreatic biopsy (c-IPB), each subject underwent CDUS with SAE imaging using Levovist. Upon identification of the biliary stricture, the IPB was taken from the area surrounding the stricture on the same imaging setting. Section diagnosis of the CDUS-IPB specimen was compared to that of the c-IPB specimen and resected tissue.ResultsBiliary strictures were identified as enhanced areas of color Doppler signal on CDUS. CDUS-IPB provided adequate specimens from the biliary strictures in all cases and corrected false-negative diagnoses by c-IPB in three cases. Section diagnosis by CDUS-IPB corresponded to the permanent section diagnosis. There were no complications.ConclusionsCDUS-IPB with Levovist is an accurate diagnostic tool. The method is especially useful for patients with a suspected malignant biliary stricture who show no tumor mass in preoperative images and no evidence of malignancy on cytologic examinations.

Abstract 408: Stem cell marker Nestin regulated the migration and invasion of pancreatic cancer cells

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Background: Nestin, a class VI intermediate filament protein, was originally described as a neuronal stem cell/progenitor cell marker. Nestin expression has also been shown to be up-regulated in progenitor cells in muscle, testis, teeth and pancreas. In the pancreas, lineage-tracing experiments have indicated that exocrine cells are derived from Nestin-expressing progenitor cells. Moreover, activation of Kras in the Nestin cell lineage is sufficient for the initiation of premalignant pancreatic intraepithelial neoplasia lesions in mice. We have reported that Nestin was expressed in 30% of human pancreatic ductal adenocarcinoma (PDAC) cases, and Nestin expression in PDAC positively correlated with nerve involvement and invasion of the peripancreatic tissue margin. Therefore, we hypothesized that Nestin may play an important role in the migration and invasive potential of PDAC cells. In this study, we used a silencing strategy to clarify the roles of Nestin in human pancreatic cancer cells. Methods: An expression vector carrying a short hairpin RNA (shRNA) targeting Nestin was stably transfected into PANC-1 and PK-45H human pancreatic cancer cells, which express high levels of Nestin. Changes in the morphology and alignment of actin filaments were analyzed using phase-contrast images and immunocytochemistry. Effects of decreased expression of Nestin on cell growth, migration in scratch and Boyden chamber assays, invasion through matrigel, and cell adhesion on extracellular matrices were examined. Differences in mRNA levels of selected signaling molecules were examined by PCR arrays. Results: Targeting Nestin with shRNA caused a marked decrease in Nestin mRNA and protein levels. Nestin shRNA-transfected cells (Nes-sh cells) exhibited a sheet-like appearance with tight cell-cell adhesion, and increased expression of filamentous (F)-actin by comparison with sham-transfected cells, whereas anchorage-dependent and -independent cell growth and cell-extracellular matrix adhesion of Nes-sh cells did not differ from those of sham cells. By contrast, migration and invasion of Nes-sh cells were markedly attenuated. To clarify the mechanisms underlying this observation, we analyzed differences in selected signaling molecules by PCR arrays that could determine the expression of mRNA closely related to tumor metastasis. The gene expressing the greatest value in Nes-sh cells was E-cadherin. Real-time PCR and western blotting confirmed that E-cadherin expression was increased in Nes-sh cells by comparison with sham cells. Conclusion: Nestin participates in the regulation of pancreatic cancer cell migration and invasion, in part, by altering F-actin and E-cadherin expression. These observations suggest that Nestin may modulate the migration of Nestin-positive progenitor cells during pancreatic development, and may serve as a novel target for suppression of invasion and metastasis in pancreatic cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 408.