Satoshi Okita

A comparison of DNA copy number changes detected by comparative genomic hybridization in malignancies of the liver, biliary tract and pancreas.

Tumors arising from the liver, biliary tract and pancreas, which originate in the foregut and are in close anatomical proximity to each other, sometimes show similar histological features. No studies have focused on genetic similarities and differences between tumors of these organs. To elucidate the similarities and differences in DNA copy number alterations between tumors of these organs, we applied comparative genomic hybridization (CGH) to cancers of the liver (31 cases), biliary tract (42 cases) and pancreas (27 cases). Some alterations were common to tumors of all three organs, and some were preferential in certain types of tumor. Gains of 1q and 8q and losses of 8p and 17p were common to all tumors. In contrast, 13q14 and 16q losses were detected exclusively in hepatocellular carcinomas (HCCs; p < 0.01). The incidence of 17q21 gain and 5q loss was higher in biliary tract cancers than in the other two types (p < 0.05). Pancreatic cancers exhibited higher incidence of 5q14-q23 gain and 19p loss than tumors of other organs (p < 0.01). Gains of 7p, 7q, 12p and 20q and losses of 3p, 6q, 9p and 18q were frequent in both biliary tract and pancreatic cancers but rare in HCCs (p < 0.05). The present results suggest that although genes located at 1q, 8p, 8q and 17p are frequently involved in HCC, biliary tract and pancreatic cancer, at least some of the genes implicated in carcinogenesis are different between these three types. It is also suggested that CGH analysis is useful as a potential adjunct for the diagnosis and management of these tumors of organs that are anatomically close to one another.

Detection of K-ras and p53 gene mutations in pancreatic juice for the diagnosis of intraductal papillary mucinous tumors.

The aim of this study was to investigate mutations of the K-ras oncogene and the p53 tumor suppressor gene in pancreatic juice and to evaluate our method for the diagnosis of intraductal papillary mucinous tumors (IPMT). Pancreatic juice was collected endoscopically from 12 patients with IPMT who underwent surgical resection (eight carcinomas and four adenomas) and eight cases without evident pancreatic diseases. DNA was extracted and both genes were examined by polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing. In addition, surgically resected specimens were analyzed for both genes by the same methods, and p53 overexpression was investigated immunohistochemically. K-ras point mutations were detected in pancreatic juice from all 12 patients (100%) and p53 mutations were detected in five of 12 (42%). They were detected not only in carcinoma but also in adenoma and there was no difference between the mutations detected in pancreatic juice and surgical specimens. No mutations were found in any cases without pancreatic diseases. These findings suggest that alterations of K-ras and p53 gene are common events in the development of IPMT and that genetic analysis of them in pancreatic juice can be a useful tool for the clinical diagnosis of IPMT before surgery.

Genetic Aberrations Detected by Comparative Genomic Hybridization in Biliary Tract Cancers

In order to elucidate cytogenetic changes characteristic of biliary tract cancer, we examined the genetic imbalances in 18 biliary tract cancers using comparative genomic hybridization (CGH). The most common sites of increases in copy number, in order of frequency, were 17q (33% of the cases), 5p (28%), 3q (22%), 7p (22%), 8q (22%), and 12p (22%), whereas copy number decreases of 6q (28%), 18q (28%), 4q (22%), 5q (22%), and 9p (22%) were frequent. The average number of chromosomal aberrations was significantly greater in stage IV than in stage III tumors (7.9 vs. 2.2/tumor, p < 0.05). The frequent aberrations detected in this study may be related to the development and/or progression of biliary tract cancers. This is the first report on CGH of biliary tract cancers.

DETECTION OF KI-RAS AND P53 GENE MUTATIONS IN TISSUE AND PANCREATIC JUICE FROM PANCREATIC ADENOCARCINOMAS

Abstract: Pancreatic carcinomas have a high incidence of Ki-ras mutations, and the genetic change is thought to occur at an early stage in the carcinogenesis. The aim of this study was to evaluate the usefulness of detecting genetic mutations in pure pancreatic juice (PPJ). DNA was extracted from tissue specimens of pancreatic carcinomas and from cells in PPJ, and subjected to polymerase chain reaction-single-strand conformation polymorphism analysis. Two types of mobility shifts that indicate Ki-ras mutations were observed in 13 of the 20 (65%) tissue specimens obtained by operation or autopsy. Ten of 15 specimens (67%) of PPJ collected from patients with pancreatic carcinomas showed two types of mobility shifts. Conventional imaging techniques did not show two in 10 of these patients. PPJ from patients with non-cancerous pancreatic diseases showed no Ki-ras mutations. The p53 tumor suppressor gene, examined by PCR-SSCP analysis, was mutated in 8 of the 20 tissue specimens obtained by operation or autopsy (40%). The detection of Ki-ras and p53 mutations in PPJ could be useful for the early diagnosis of pancreatic carcinomas, especially for neoplastic lesions of the intraductal type.

p53 Mutations in Two Patients with Intraductal Papillary Adenoma of the Pancreas

There has been no report on p53 gene mutation in benign human pancreatic intraductal tumors. We examined pancreatic juice and tissue specimens from two patients with intraductal papillary adenoma of the pancreas by polymerase chain reaction‐single‐strand conformation polymorphism analysis and direct sequencing and found point mutations of p53 gene resulting in amino acid substitutions in exons 6 and 8. Thus, p53 gene mutation may be an early event in the neoplastic process of some pancreatic intraductal tumors and may play an important role in tumorigenesis.

Simple and sensitive detection of K-ras gene mutations in human pancreatic cancers by nonradioisotopic single-strand conformation polymorphism analysis.

In an attempt to determine the best indications for the classically adopted ileo-rectal anastomosis (IRA) and the new techniques of restorative proctocolectomy, namely, ileal J-pouch-anal anastomosis (IAA) ilea J-pouch-anal canal anastomosis (IACA), we retrospectively studied 72 surgically treated patients with ulcerative colitis (UC) followed in our surgical department in the period between 1963 and 1994. Compared to these new techniques, IRA had a lower incidence of postoperative fecal incontinence, and was one-stepped in the majority of the patients. No significant difference regarding postoperative bowel function, operation time, volume of bleeding, hospital stay, and the need for postoperative prednisolone was observed. We concluded that IRA is a good procedure that is indicated for patients receiving high-dose prednisolone, for those who need a quick return to social activity, and for those with poor anal function. IACA is a good indication for those patients with good anal function assessed preoperatively, who agree to receive a multi-step operation. For those patients with cancer or dysplasia, IAA should be the operation of first choice.