Tamotsu Kuroki

The Tumor Suppressor Gene WWOX at FRA16D Is Involved in Pancreatic Carcinogenesis

Purpose: WWOX (WW domain containing oxidoreductase) is a tumor suppressor gene that maps to the common fragile site FRA16D. We showed previously that WWOX is frequently altered in human lung and esophageal cancers. The purpose of this study was to delineate more precisely the role of WWOX in pancreatic carcinogenesis. Experimental Design: We analyzed 15 paired pancreatic adenocarcinoma samples and 9 pancreatic cancer cell lines for WWOX alterations. Colony assay and cell cycle analysis were also performed to evaluate the role of the WWOX as a tumor suppressor gene. Results: Loss of heterozygosity at the WWOX locus was observed in 4 primary tumors (27%). Methylation analysis showed that site-specific promoter hypermethylation was detected in 2 cell lines (22%) and treatment with the demethylating agent 5-aza-2′-deoxycytidine demonstrated an increase in the expression of WWOX. In addition, 2 primary tumor samples (13%) showed promoter hypermethylation including the position of site-specific methylation. Transcripts missing WWOX exons were detected in 4 cell lines (44%) and in 2 tumor samples (13%). Real-time reverse transcription PCR revealed a significant reduction of WWOX expression in all of the cell lines and in 6 primary tumors (40%). Western blot analysis showed a significant reduction of the WWOX protein in all of the cell lines. Furthermore, transfection with WWOX inhibited colony formation of pancreatic cancer cell lines by triggering apoptosis. Conclusion: These results indicate that the WWOX gene may play an important role in pancreatic tumor development.

A non-randomized comparative study of laparoscopy-assisted pancreaticoduodenectomy and open pancreaticoduodenectomy.

BACKGROUND/AIMS Laparoscopic surgery for periampullary disease is still a challenging operation. The aim of this study was to compare the perioperative outcomes of patients undergoing conventional pancreaticoduodenectomy (PD) with the outcomes of those undergoing laparoscopy-assisted PD. METHODOLOGY A retrospective analysis was conducted on 51 consecutive patients who underwent laparoscopy-assisted or open PD for periampullary disease. RESULTS There were no significant differences in the preoperative demographic or clinical data of the two study groups. Although there were no significant differences in the operative time between the two study groups, blood loss in the laparoscopy-assisted PD group was significantly smaller than that in the open PD group. There were no significant differences in the occurrence of postoperative complications between the two groups. CONCLUSIONS Laparoscopy-assisted PD is a feasible and safe surgical procedure that provides the advantages expected from a minimally invasive surgery including less blood loss.

Evidence for the presence of two tumour-suppressor genes for hepatocellular carcinoma on chromosome 13q.

The concept that genetic changes accumulate during development and progression of cancer is widely accepted. Frequent allelic losses at chromosome 13q have been found in hepatocellular carcinomas (HCCs), and a known tumour-suppressor at 13q14, the retinoblastoma (RB) gene, is thought to be the target of those events. However, no strong evidence has emerged to support a significant role of RB during hepatocarcinogenesis. To investigate the minimal area(s) of loss on chromosome 13q in HCCs, we analysed DNAs isolated from 92 tumours for loss of heterozygosity (LOH) at 13 loci on chromosome 13q, using polymorphic microsatellite markers. In 30 (32.6%) of 92 cases we detected LOH for at least one locus on chromosome 13q and 20 revealed a partial or interstitial deletion of chromosome 13q. Deletion mapping of these 20 tumours indicated two separate commonly deleted regions: one was located in the region including RB and the other was located in the region including the BRCA2 locus. These findings suggest that at least one putative tumour-suppressor gene for HCC other than RB, possibly BRCA2, exists on chromosome 13q.

An intraductal papillary component is associated with prolonged survival after hepatic resection for intrahepatic cholangiocarcinoma.

The outcome after surgery for intrahepatic cholangiocarcinoma (ICC) is dismal and data on long‐term survival are not available. This study evaluated prognostic indicators and characteristic features of long‐term survivors after hepatic resection for ICC.

Association of cumulative allelic losses with tumor aggressiveness in hepatocellular carcinoma.

BACKGROUND/AIMS Loss of heterozygosity on various chromosomal arms has been reported in hepatocellular carcinoma and a multistep accumulation of genetic alteration has become accepted as the mechanism underlying progression of the disease. Although cumulative genetic alterations may imply more malignant tumors with poorer prognosis, the assumption requires further investigation. METHODS Presence of loss of heterozygosity was analyzed by microsatellite markers at 13 loci on six chromosomal arms in 56 hepatocellular carcinomas. Association with cumulative allelic losses and prognosis of the patient following curative resection was studied. RESULTS Frequency of allelic losses at each chromosomal arm was 31% on 1p, 20.6% on 4q, 17.5% on 8p, 17.5% on 13q, 25.5% on 16q and 17.4% on 17p. Thirty-three tumors (59%) presented loss of heterozygosity. Tumors with more allelic losses were significantly more likely to be un-infected by hepatitis C virus, and to be histologically poorly differentiated, to have higher alpha-feto protein value, to be advanced in T classification and in tumor stage. Patients with more than one loss of heterozygosity revealed poorer 3-year disease-free survival than those with one or no (p=0.0004). A multivariate Cox model analysis revealed cumulative loss of heterozygosity as an independent and influential factor for disease recurrence (relative risk, 2.66; 95% confidence interval, 1.23-5.75; p=0.013), followed by tumor stage. CONCLUSIONS Cumulative loss of heterozygosity reflects the multistep genetic mechanism of progression of hepatocellular carcinoma. The study confirms the potential significance of genetic analysis in the management of the disease.

Genetic alterations in gallbladder carcinoma.

Gallbladder carcinoma is an aggressive cancer associated with a poor prognosis. Unfortunately, the precise molecular mechanisms of development and progression of this highly malignant tumor remain unknown. It is still unclear whether loss of heterozygosity (LOH) plays a significant role in gallbladder carcinogenesis, but recent studies have found a high incidence of LOH at several chromosomes in gallbladder carcinoma. In particular, LOH on chromosomes 1p, 3p, 5p, 8p, 9p, 9q, 13q, 16q, and 17p has been highlighted and LOH on 3p, 9p, 13q, 16q, and 17p has been detected in preneoplastic lesions and in the early phase of gallbladder carcinoma during multistep carcinogenesis. The proto-oncogene, K-ras, is the best known genetic alteration in several human neoplasms, including gallbladder carcinoma. The accumulation of these genetic changes leads to a disruption in cell-cycle regulation and also continuous cell proliferation. We present an overview of K-ras alteration and LOH at several chromosome loci in gallbladder carcinoma. Further studies of the molecular mechanism in gallbladder carcinoma and the delineation of the genetic influence involved should promote our understanding of gallbladder carcinogenesis.

Stenting versus non-stenting in pancreaticojejunostomy: a prospective study limited to a normal pancreas without fibrosis sorted by using dynamic MRI.

Objectives: We prospectively investigated the efficacy of an external pancreatic duct stent to prevent pancreatic fistula in the nonfibrotic pancreas after pancreaticojejunostomy, in which the degree of pancreatic fibrosis was assessed objectively by using dynamic magnetic resonance imaging (MRI). Methods: Among the 67 consecutive patients who underwent pancreatic head resection, 45 patients were judged to have a normal pancreas without fibrosis based on the preoperative assessment of pancreatic fibrosis based on MRI. The patients were randomly allocated to 1 of 2 groups with (n = 23) or without (n = 22) use of an external pancreatic duct stent in performing a pancreaticojejunostomy. Results: Pancreatic fistula developed in 8 (34.5%) patients in the stented group: 3 grade A and 5 grade B; whereas in the nonstented group, 9 (40.9%) patients developed pancreatic fistula: 3 grade A and 6 grade B. There were no significant differences in the incidence or severity of pancreatic fistula between the 2 groups. Conclusions: The utility of the external pancreatic duct stent after pancreaticojejunostomy was not found in the nonfibrotic pancreases, which were sorted according to the degree of pancreatic fibrosis using the pancreatic time-signal intensity curve analysis from MRI.

The risk factors and predictive factors for anastomotic leakage after resection for colorectal cancer: reappraisal of the literature

Anastomotic leakage is a serious complication that can occur after colorectal surgery. Several risk factors for anastomotic leakage have been reported based on the findings of prospective and retrospective studies, including patient characteristics, the use of neoadjuvant therapy, the tumor location, intraoperative events, etc. However, as these risk factors affect each other, the statistical results have differed in each study. In addition, differences in surgical methods, including laparoscopy versus laparotomy or stapling anastomosis versus handsewn anastomosis, may influence the incidence of anastomotic leakage. This mini-review summarizes the results of reported papers to clarify the current evidence of risk factors for anastomotic leakage.

Intraoperative portal venous pressure and long‐term outcome after curative resection for hepatocellular carcinoma

Outcomes of liver resection for hepatocellular carcinoma (HCC) have improved owing to better surgical techniques and patient selection. Portal hypertension may influence outcome but the preoperative definition and role of portal hypertension are far from clear. The aim of this study was to elucidate the influence of portal venous pressure (PVP) measured directly during surgery on outcomes of liver resection in patients with HCC.

Role of hypermethylation on carcinogenesis in the pancreas.

Pancreatic cancer is a disease with a dismal outcome and a 5-year survival rate of under 5%. Recent studies have shown that pancreatic cancer consists of an accumulation of genetic and epigenetic alterations during tumor development as in other human cancers. Therefore, new diagnostic methods for early detection and more effective therapeutic strategies based on a better understanding of the molecular biology of pancreatic cancer are urgently required. Recently, promoter hypermethylation of cancer-related genes has emerged as an important mechanism in carcinogenesis. The present review summarizes an overview of the alterations of promoter hypermethylation in pancreatic cancer, and suggests that the further study of promoter hypermethylation involvement in pancreatic cancer and the delineation of molecular mechanisms involved may lead to an improvement in the outcome of this aggressive disease.