Microsatellite instability and alteration of E2F-4 gene in adenosquamous and squamous cell carcinomas of the stomach

Microsatellite instability (MSI) due to defective DNA mismatch repair (MMR) is a form of genomic instability underlying the tumorigenesis of various human neoplasms. To evaluate the roles of MSI in the pathogenesis of gastric carcinomas with squamous differentiation, 17 primary stomach cancer patients (15 adenosquamous and two squamous cell carcinomas) were examined for MSI frequency using five microsatellite markers and the criteria for MSI recommended by the National Cancer Institute Workshop. The molecular causes and consequences of MSI in these neoplasms were further researched through the immunohistochemistry of MMR proteins and the mutational analysis of cancer-associated genes targeted by MSI, respectively. Two of the 17 (12%) cases demonstrated MSI at the most examined loci and were classified as having high level MSI (MSI-H). These tumors also exhibited frame-shift mutations at mononucleotide repeats in the target genes, including TGFbetaRII, IGFIIR, BAX, and hMSH6. It is interesting to note that the mutations of the serine (AGC)13 repeats within the E2F-4 gene were found only in the squamous cell carcinoma portions of them, whereas such alterations were not detected in any of the adenocarcinomatous portions. This suggests that E2F-4 might be implicated in the transformation of adenocarcinoma into squamous cell carcinoma and further studies are needed to understand its role in squamous differentiation.

Loss of heterozygosity in gastric neuroendocrine tumor

The MEN1 gene locus is known to be partly responsible for the tumorigenesis of sporadic gastric neuroendocrine tumors, but the genetic events that drive the neoplastic process of this tumor remain largely unknown. In order to screen the tumor suppressor genes associated with the tumorigenesis of gastric neuroendocrine tumors, 15 neuroendocrine carcinomas and three carcinoid tumors in the stomach were analyzed for loss of heterozygosity (LOH) using 22 microsatellite markers. In our study, the gastric neuroendocrine tumors showed a high rate of LOH in chromosomes 8p (82%), 15q (58%), 17p (57%), llp (50%), 12p (50%) and 13q (50%). The mean fractional allelic loss (FAL) was higher in the neuroendocrine carcinoma components than in the adenocarcinoma components (0.42 versus 0.33, respectively). In four cases, the adenocarcinoma components showed discordant LOH patterns from those of the neuroendocrine counterparts in half of the informative chromosomes analyzed. Comparably, the gastric neuroendocrine carcinomas exhibited a higher LOH frequency on 8p and a lower LOH on 7q than did the gastric adenocarcinomas. It is suggested that chromosome 8p is the possible location of the tumor suppressor genes associated with the tumorigenesis of gastric neuroendocrine tumors.

Methylation of specific CpG sites in the promoter region could significantly down-regulate p16(INK4a) expression in gastric adenocarcinoma

Silencing of p16(INK4a) by methylation of the CpG islands in the promoter region has been found to be an alternative mechanism of inactivation in several tumors. However, in gastric carcinoma, the relationship between methylation status and the transcriptional silencing of the p16 gene remains to be clarified. In this study, we investigated whether methylation of a few specific CpG sites in the promoter region could significantly down-regulate p16 activity in the tumorigenesis of gastric carcinoma. By Southern analysis and bisulfite-modified genomic sequencing of 9 gastric-carcinoma cell lines, we found that the 5 cell lines (55.5%) not expressing p16 mRNA had methylated CpG sites at the promoter region of p16. In addition, we analyzed the p16-protein expression of 28 primary gastric carcinomas and their normal counterparts by immunohistochemical staining (IHC) on paraffin sections. Loss of p16 expression was detected in 6 cases (22%). In 5 out of these 6 (83%), the actual p16 gene was inactivated by de novo methylation of the promoter sites. Taken together, these results suggest a strong correlation between de novo methylation of a few specific CpG sites and transcriptional silencing of the p16 gene in gastric carcinoma.

Methylation of specific CpG sites in the promoter region could significantly down-regulate p16(INK4a) expression in gastric adenocarcinoma

Silencing of p16(INK4a) by methylation of the CpG islands in the promoter region has been found to be an alternative mechanism of inactivation in several tumors. However, in gastric carcinoma, the relationship between methylation status and the transcriptional silencing of the p16 gene remains to be clarified. In this study, we investigated whether methylation of a few specific CpG sites in the promoter region could significantly down-regulate p16 activity in the tumorigenesis of gastric carcinoma. By Southern analysis and bisulfite-modified genomic sequencing of 9 gastric-carcinoma cell lines, we found that the 5 cell lines (55.5%) not expressing p16 mRNA had methylated CpG sites at the promoter region of p16. In addition, we analyzed the p16-protein expression of 28 primary gastric carcinomas and their normal counterparts by immunohistochemical staining (IHC) on paraffin sections. Loss of p16 expression was detected in 6 cases (22%). In 5 out of these 6 (83%), the actual p16 gene was inactivated by de novo methylation of the promoter sites. Taken together, these results suggest a strong correlation between de novo methylation of a few specific CpG sites and transcriptional silencing of the p16 gene in gastric carcinoma.

Genetic alterations in gastric cancer cell lines and their original tissues

To investigate the genetic changes that occur during establishment of gastric cancer cell lines, 4 gastric cancer cell lines and their original tumor tissues were examined for microsatellite instability (MSI), loss of heterozygosity (LOH), and p53 mutation. MSI status did not change during the establishment, though the cell lines gained frameshift mutation in some of the genes with polytract coding sequences. There was no difference in p53 mutation between the cell lines and the original tumors. The frequency of LOH was similar between the cell lines and each original tumor, in the range 30.8% to 85.7%. The difference in the LOH results between the cell lines and the original tumors was not greater than the difference between the different areas of the original tumors. The above results suggested that most of the genetic alterations, such as MSI, LOH, and p53 gene mutation, were sustained during the establishment of gastric cancer cell lines. Minor genetic differences between original tumor tissues and cancer cell lines could be explained as a tumor heterogeneity because separate areas of the original tumor tissues manifest similar variations.

Clinicopathologic study of Castleman's disease in Korea

Castleman's disease represents an atypical lymphoproliferative disorder, infrequently associated with various immunologic abnormalities or subsequent development of malignancy such as Kaposi sarcoma, malignant lymphoma and plasmacytoma. Its clinicopathologic features depend on various etiologic factors such as Kaposi sarcoma herpesvirus (KSHV), oversecretion of IL-6, adhesion molecule and follicular dendritic cell dysplasia, etc. To investigate the relationship of Castleman's disease (CD) and the above factors, we reviewed 22 cases of CD. Four cases of KSHV positive CD were detected, all multicentric, plasma cell type, and these cases displayed prominent vascular proliferation, characteristic 'Kaposi-like lesion'. IL-6 and CD54 positive mononuclear cells were scattered in interfollicular areas of KSHV positive cases. Follicular dendritic cell hyperplasia, vascular proliferation, expression of IL-6 and CD54 did not show any significant difference between solitary vs multicentric type, and plasma cell type vs hyaline vascular type. Our study suggests that KSHV positive CD reveals unique pathologic features, and the probable relationship of KSHV and IL-6 and CD54 is discussed.

Hamartomatous gastric polyposis in a patient with tuberous sclerosis

A 42-year-old female diagnosed with tuberous sclerosis was found to have multiple polyps in the fundus of stomach. On histologic examination, the lesions were hamartomatous polyps. In tuberous sclerosis, many lesions occur in multiple organs and there are several reports about the frequent association of hamartomatous polyps of the colon. However, gastric manifestation of tuberous sclerosis has not been established probably due to its asymptomatic nature. This is the first report of multiple gastric hamartomatous polyposis in patient with tuberous sclerosis.

Production and characterization of immortalized rat hepatocytes secreting hepatocyte growth factor/scatter factor

BACKGROUND/AIMS

Hepatocyte transplantation is a recently attractive field in the treatment of liver failure and enzyme-deficient diseases. However, procurement of sufficient quantities of hepatocytes is almost impossible. We attempted to create a hepatocyte cell line that could be used for hepatocyte transplantation.

METHODOLOGY

L2A2 is a conditionally immortalized rat hepatocyte cell line produced by transfection of temperature-sensitive simian virus T antigen to the hepatocytes in the Lewis rat. Hepatocyte Growth Factor/Scatter Factor (HGF/SF)-secreting L2A2 cells, designated as SF-21, was produced by transfecting human HGF/SF cDNA into L2A2 cells.

RESULTS

This cell line was able to produce HGF/SF at the rate of 5-10 ng/10(6) cells/24 hrs, and the recombinant HGF/SF was of the expected size and was functionally active in that it could scatter Madin-Darby canine kidney cells. The SF-21 cells grew faster than its parental cell clone, and survived and proliferated at 37 degrees C in vitro. Also, the SF-21 cells were able to survive and proliferate when transplanted into the spleen of syngeneic rat, and expressed glucose-6-phosphatase.

CONCLUSIONS

These HGF/SF-secreting hepatocytes can be used as a model system to test a feasibility of using genetically engineered hepatocyte cell line for hepatocyte transplantation in the rat.

Microsatellite instability and Epstein-Barr virus infection in gastric remnant cancers

Clinicopathological analysis, microsatellite analysis, detection of Epstein-Barr virus (EBV), and immunohistochemistry on p53 protein were performed in 26 cases of gastric remnant cancer (GRC). They were divided into two groups; Group A (n = 14) who had undergone a primary gastrectomy for benign gastric disease, and Group B (n = 12) who had undergone the same operation for gastric cancer. EBV infection was present in 29% of Group A, 8% of Group B and 6% of the conventional gastric carcinoma (CGC) (Group A vs CGC, P = 0.01). Microsatellite instability (MSI) was found in 7% of Group A, 25% of Group B, and 9% of the CGC (Group B vs CGC; P = 0.08). p53 Overexpression was observed in 46% of the GRC and 33% of the CGC. p53 Overexpression was observed in 90% of the intestinal type of GRC, but in only 20% of the diffuse type of GRC (P = 0.002). The cancer stage was a significant factor in the univariate analysis of survival (P = 0.04). In conclusion, GRC is different from CGC in terms of MSI or EBV association. The pathogenetic differences between the two groups require further investigation. EBV infection may have been involved in the carcinogenesis of Group A. MSI may be an important factor in the carcinogenesis of metachronous multiple gastric cancer (Group B).

Allelotype analysis of intrahepatic cholangiocarcinoma

To identify the chromosomal loci of allelic loss in intrahepatic cholangiocarcinoma (ICC), we performed an allelotype study of 36 ICCs using 55 genome-wide microsatellite markers. Loss of heterozygosity was found most frequently on 8p (65.6%), 17p (64.7%), and 9p (64.5%), followed by 18q (54.2%), 1p (48.5%), 3p (44.8%), 9q (42.1%), 14q (41.7%), 6q (41.7%), and 1q (40.6%). The fractional allelic loss (FAL) values ranged from 0 to 0.731 (mean, 0.322). Analysis of the relationship between FAL values and clinicopathologic parameters disclosed significantly higher FAL values in moderately to poorly differentiated ICCs than in well-differentiated ones (P < .05). In summary, this study defined for the first time the overall number of chromosomes having allelic loss and the chromosomal arms and/or regions potentially involved in the development of ICC.

Histopathologic analysis of in-stent neointimal regression in a porcine coronary model

BACKGROUND

Animal and clinical studies have demonstrated late regression of in-stent neointima. This study was performed to identify the temporal changes in the in-stent neointimal constituents responsible for late regression.

METHODS

NIR stents were implanted in porcine coronary arteries (size of stent (in mm) to size of artery (in mm) approximately equal to 1.1) and harvested at 2 months and 6 months (n = 6 stents/group). Histopathologic analyses included morphometric analysis, smooth muscle cell density, and extracellular matrix contents.

RESULTS

Compared with the findings at 2 months, at 6 months there was a significant reduction in area stenosed (from 21 +/- 3% to 14 +/- 1%, P < 0.05) and neointimal thickness (from 0.2 +/- 0.03 mm to 0.03 +/- 0.02 mm, P < 0.05), despite similar injury scores (0.05 +/- 0.06 at 2 months and 0.36 +/- 0.29 at 6 months). This regression was accompanied mainly by a reduction in proteoglycan (from 24 +/- 19% to 5 +/- 8%, P = 0.05), with no change in smooth muscle cell density (71 +/- 7 compared with 76 +/- 23/high power field) or collagen content (25 +/- 19% compared with 25 +/- 19%).

CONCLUSIONS

The study confirmed the regression of in-stent neointima, which was mainly attributable to a reduction in proteoglycan content, resembling the natural healing response.

Decreased trabecular bone mineral density in newly diagnosed inflammatory bowel disease patients in Korea

BACKGROUND

Decreased bone mineral density (BMD) is common in Western patients with inflammatory bowel disease (IBD). However, BMD has never been studied in Asia where the demographic and socio-economic status are different from the West. The aim of this study was to investigate the prevalence and mechanisms of osteopenia in newly diagnosed Korean patients with IBD.

METHODS

We studied 14 patients with Crohn's disease (CD) and 25 patients with ulcerative colitis (UC), all of whom had never been treated with corticosteroids. Bone mineral density was measured in the lumbar spine and the femoral neck by dual energy X-ray absorptiometry. Biochemical parameters including serum osteocalcin, parathyroid hormone, plasma inactive and active vitamin D, and urinary deoxypyridinoline were measured.

RESULTS

The BMD Z score at the lumbar spine was lower both in CD and in UC patients, but there was no significant difference between the two groups. There was no significant difference in nutritional status or biochemical parameters of bone metabolism between patients with a normal BMD and those with a decreased BMD.

CONCLUSIONS

Low BMD at the lumbar spine is common in newly diagnosed Korean patients with IBD, a result which is similar to Western studies. The mechanism for low bone mass remains undetermined; however, nutritional status and hormonal parameters of bone metabolism, and ethnic differences are not likely to be an important factor in the pathogenesis of this bone loss.

Involvement of p27(kip1) in ceramide-mediated apoptosis in HL-60 cells

Ceramide acts as a mediator of apoptosis in various cell lines, but little is known regarding the molecular mechanism linked to the cell cycle. In the present study, we examined the expression of p27(kip1) and its relationship to apoptosis induced by ceramide. We demonstrated that treatment of HL-60 cells with C6-ceramide resulted in G1 phase elevation followed by apoptotic cleavage associated with increase in the level of cdk inhibitor p27(kip1). Ceramide inhibited the kinase activities of cdk2 and cdk4 within 24 h of treatment. Ceramide-induced inhibition of cdk2 and cdk4 kinase activities was accompanied by increase of p27(kip1) in the cdks complexes. In addition, we have shown that both the cell death and expression of p27(kip1) protein induced by ceramide were significantly decreased in HL-60 cells overexpressing bcl-2. Furthermore, ceramide induced a significant increase in Bax protein expression coincided with increase in p27(kip1) protein level. These findings indicate that p27(kip1) may play important roles in mediating ceramide-induced apoptosis and its expression can be regulated by Bax and Bcl-2.

Role of caspase-3 in apoptosis of colon cancer cells induced by nonsteroidal anti-inflammatory drugs

Epidemiological studies have demonstrated that nonsteroidal anti-inflammatory drugs (NSAIDs) decrease the incidence of and mortality from colon cancer. In addition, NSAIDs reduce the number and the size of polyps in patients with familial adenomatous polyposis. The mechanisms responsible for the antineoplastic effect of NSAIDs are not yet completely understood, but one of the possible mechanisms is an induction of apoptosis. We explored the role of caspase-3, a major apoptosis-executing enzyme, in NSAID-induced apoptosis of colon cancer cell line HT-29. Treatment of HT-29 cells with indomethacin induced a dramatic increase in caspase-3-like protease activity measured by a cleavage of the fluorogenic substrate Ac-DEVD-AMC. Western blot analysis showed that indomethacin treatment led both to decrease in procaspase-3 and to cleavage of its substrate poly(ADP-ribose) polymerase (PARP). Furthermore, the caspase-3-like protease inhibitor Ac-DEVD-CHO attenuated indomethacin-induced DNA fragmentation dose dependently. However, mRNA expression of CASP genes was not affected by the addition of indomethacin, highlighting the importance of posttranslational modification of this enzyme for the activation. These results suggest that NSAIDs, including indomethacin, induce apoptosis in colon cancer cells through a caspase-3 dependent mechanism which may contribute to the chemopreventive functions of these agents.

Intraportal insulin therapy after partial hepatectomy for hepatoma patients with insulinopenia

BACKGROUND/AIMS

This prospective study was carried out in order to assess the role of intraportal insulin infusion after partial hepatectomy in hepatoma patients with insulinopenia.

METHODOLOGY

Of the 38 patients who underwent hepatic resection for hepatocellular carcinoma from August 1994 to August 1995, 21 patients took an oral glucose tolerance test with insulin measurement preoperatively. Five patients were treated postoperatively with intraportal insulin infusion, as follows: A 16-gauge catheter was inserted into a reopened umbilical vein and fixed in place by a few absorbable stitches. Regular insulin was administered just after the operation at the rate of 2 units/hour for 2-3 weeks. Blood glucose levels were maintained between 150 and 200 mg/dL. Arterial ketone body ratio was used in monitoring the function of the liver during the perioperative periods.

RESULTS

Ten patients (47.6%) were found to be insulinopenic. In the insulin therapy group (n = 5), the arterial ketone body ratio of 3 patients recovered within a few hours after the operation, and that of the remaining 2 patients recovered on the 1st postoperative day. But in the control group (n = 5), none of the 5 cases had an arterial ketone body ratio of more than 0.7 on the day of operation. The arterial ketone body ratio returned to normal on the 1st postoperative day in 2 cases, on the 2nd postoperative day in 1 case, and on the 5th day in 1 case. The arterial ketone body ratio recovery time was shorter in the intraportal insulin therapy group than in the control group (P = 0.042).

CONCLUSIONS

Intraportal insulin infusion after hepatectomy via the reopened umbilical vein may be a very simple and safe means of promoting recovery of remnant liver function after hepatectomy in hepatoma patients with insulinopenia.

Relation between the risk of gallstone pancreatitis and characteristics of gallstone in Korea

BACKGROUND/AIMS

Pancreatitis is a serious complication of patients with gallstones. However, risk factors of gallstone pancreatitis were unpredictable until recently. In Korea, characteristics of gallstones are different from Western countries. The present study was designed to determine differences in the risk of gallstone pancreatitis and characteristics of gallstones in Korean patients.

METHODOLOGY

Clinical data were collected on patients undergoing laparoscopic cholecystectomy. The physical characteristics of gallstones recovered at surgery were also recorded. Patients with gallstone pancreatitis were compared with patients who had uncomplicated biliary pain.

RESULTS

In a logistic regression model, acute gallstone pancreatitis was associated with a stone diameter of less than 5 mm (odds ratio: 3.3695; P = 0.0352) and with stone number of more than 20 (odds ratio: 3.8686; P = 0.0361). No other variable, including pigment stone, age, and sex, remained statistically significant in the adjusted analysis (P > 0.05).

CONCLUSIONS

Patients with at least 1 gallstone smaller than 5 mm in diameter and stone number more than 20 each have a more than 3-fold increased risk of presenting with acute gallstone pancreatitis. The composition of gallstones, especially pigment stones, was not an important risk factor in gallstone pancreatitis in Korean patients with stones having a different composition than those from Western countries.

Systematic analysis of the effects of hepatocyte transplantation on rats with acute liver failure

BACKGROUND/AIMS

Acute liver failure either after liver resection or as part of underlying liver disease is still associated with high mortality. Hepatocyte transplantation in various forms has attracted attention recently. However, none of those reports have investigated the thorough and systematic analysis of effect of hepatocyte transplantation on acute liver failure induced by 90% hepatectomy. Therefore, we investigated systematic analysis of effect of hepatocyte transplantation on rats with acute liver failure.

METHODOLOGY

Male Sprague-Dawley rats were used. Group I rats (n = 26) received intrasplenic injection of 2 x 10(7) hepatocytes in 0.3 mL Dulbecco's modified Eagle's medium (DMEM) 24 hours prior to 90% hepatectomy. Group II rats (n = 24) received intrasplenic injection of DMEM only. Twenty-two rats from group I and 20 from group II were observed for the determination of survival time. The remaining 8 (4/each group) rats were used to assess the liver function and regeneration.

RESULTS

The hepatocyte bearing spleen revealed active glucose-6-phosphatase activity. In group I rats, the survival was longer and that group had more long-term survivors than those of group II controls. In group I, there was significant increase in the ratio of weight of remnant liver lobes to body weight. At 24 hours after hepatectomy, group I rats had improved biochemical parameters compared to those of group II rats.

CONCLUSIONS

In rats with acute liver failure, intrasplenic hepatocyte transplantation acts as a bridge to support experimental rats from acute liver failure to liver regeneration, prolong survival in rats with acute liver failure and improve biochemical parameters.

Significance of rectosigmoid polyp as a predictor of proximal colonic polyp

The association between rectosigmoid polyps and polyps in the more proximal colon is still a matter of debate, and the need for colonoscopy in patients with rectosigmoid polyps that are detected by flexible sigmoidoscopy is controversial. The aim of this study was to determine whether or not certain characteristics of rectosigmoid polyps are associated with the presence and characteristics of proximal colonic polyps. Seven hundred and twenty-eight patients who underwent total colonoscopy between October 1995 and June 1998 and who had colorectal polyps were retrospectively analyzed. Patients with inflammatory bowel diseases, familial adenomatous polyposis, or any advanced cancer were excluded. The odds ratio (OR) and 95% confidence interval (CI) of prevalence of proximal colonic polyps according to the patients age and sex, as well as the characteristics of rectosigmoid polyps, were calculated. Advanced adenoma was defined as an adenoma larger than 10 mm or an adenoma of any size with villous component, high-grade dysplasia or invasive carcinoma. Among 728 patients with colorectal polyps, 356 patients (48.9%) had polyps only in the rectosigmoid region, 193 patients (26.5%) had polyps only in the proximal colon, and 179 patients (24.6%) had polyps in both the rectosigmoid and proximal colon. In 535 patients with rectosigmoid polyps, the prevalence of proximal colonic polyps, neoplastic polyps and advanced adenomas were 33.4%, 27.3% and 2.9%, respectively. The prevalence of proximal colonic polyps in patients with rectosigmoid polyps was found to be significantly related to the male gender and elderly patients, in addition to the neoplastic histology of the rectosigmoid polyps. However, the prevalence of the proximal colonic polyps was not related to the size, number and shape of rectosigmoid polyps. In 179 patients with both rectosigmoid and proximal colonic polyps, the characteristics of proximal colonic polyps such as size, number and shape were similar to those of rectosigmoid polyps. We recommend total colonoscopic examination in all patients with rectosigmoid adenomas, regardless of the size, number, and shape, especially in elderly males.

Microsatellite instability in the adenoma-carcinoma sequence of the stomach

Sixty-three cases of stomach resections harboring both adenoma and carcinoma were analyzed for microsatellite instability (MSI). The cases included 28 carcinomas arising from adenoma (Type I) and 35 carcinomas with separate adenoma (Type II). The results of MSI assessed by 49 markers were the same for BAT-26 instability. The incidence of MSI was 21% in gastric adenoma and 30% in gastric carcinoma, which is significantly higher than gastric carcinoma without associated adenoma (p < 0.01). Five of eight (63%) cases of multiple carcinomas associated with adenoma showed MSI+ in adenoma and in one or more carcinoma lesion(s). Eight of thirteen (62%) MSI+ adenomas were associated with carcinoma, whereas 20 of 50 (40%) MSI adenomas were associated with carcinoma. MSI+ adenomas of Type I showed a higher mutation rate of the TGF-beta RII gene than Type II (88% versus 40%). Gastric adenoma with TGF-beta RII gene mutation was more prone to transform into carcinoma (p = 0.03). This study revealed that gastric carcinoma arising from adenoma is frequently associated with a mismatch repair deficiency mechanism. In the gastric adenoma-carcinoma sequence, TGF-beta RII gene mutation occurred early in the adenoma stage and it persisted after malignant transformation.

Establishment and characterization of seven human renal cell carcinoma cell lines

OBJECTIVE

To establish human renal cell carcinoma (RCC) cell lines, and to investigate the cell phenotypes and molecular characteristics of human RCC cell lines and their corresponding tumour tissues.

MATERIALS AND METHODS

Seven human RCC cell lines from pathologically proven RCCs were established. The histopathology of the primary tumours, in vitro growth characteristics and status of tumour suppressor genes, mismatch repair genes and microsatellite instability (MSI) were examined in cell lines and their corresponding tumour tissues. Five of the cell lines were derived from clear cells (SNU-228, -267, -328, -349, and -1272), one from granular cells (SNU-482), and one from mixed clear and granular cell types (SNU-333). The mutational status was compared for von Hippel-Lindau (VHL), p53, TGF-beta type II receptor (TGF-betaRII), hMSH2, and hMLH1 genes in the cell lines and their corresponding tumour tissues. The MSI status of the cell lines was determined by screening for adenine repeat sequences, e.g. BAT-25, BAT-26, and BAT-40.

RESULTS

All lines showed different doubling times and were confirmed by DNA fingerprinting analysis to be unique. Contamination by mycoplasma or bacteria was excluded. In two cell lines (SNU-349 and -1272) and their tumour tissues, mutations in the VHL gene were found. The SNU-267 line had a frameshift mutation in the p53 gene. A missense mutation of the TGF-betaRII gene was detected in the SNU-1272 line and the corresponding tissue. Analysis of the repeat sequences showed one cell line (SNU-349) to have MSI and the other six to have microsatellite stability. As MSI is a hallmark of the inactivation of mismatch repair genes, the presence of hMSH2 and hMLH1 mutations was investigated in all seven cell lines. An inactivating homozygous single base-pair deletion of the hMLH1 gene was found only in the SNU-349 cell line and corresponding tissue. Moreover, a frameshift mutation within an 8-bp polyadenine repeat present in the hMSH3 coding region was found only in the MSI cell line and tumour tissue.

CONCLUSION

These newly established RCC cell lines should provide a useful in vitro model for studies related to human RCC. The SNU-349 cell line should be especially useful for studies of MSI and mismatch repair-defective RCCs.

Clinicopathologic correlation of p53 protein overexpression in adenoma and carcinoma of the ampulla of Vater

It has been well documented that ampullary carcinoma arises from a precancerous lesion, but there have been few studies concerning changes at the molecular level during the adenoma-carcinoma sequence. In this study, p53 overexpression during the progression of carcinoma was compared and the relation between p53 expression and prognosis was analyzed. Ninety-four cases of adenocarcinoma of the ampulla of Vater were reviewed histopathologically and examined for overexpression of p53 protein using the DO-7 (mouse monoclonal; DAKO, Glostrup, Denmark) antibody. The correlation of p53 overexpression with the existence of adenoma, clinical stage, histologic grade, and overall survival was investigated. The proportion of p53-positive cases among normal mucosa, adenoma, early stage carcinoma (I and II), advanced stage carcinoma (III and IV), and metastatic lesion was 0% (0/94), 14.3% (6/42), 32.3% (20/62), 53.1% (17/32), and 63.3% (19/30), respectively. The existence of adenoma or histologic grade of carcinoma did not correlate with p53 overexpression. The carcinoma having adenomatous component was more common in early stages (54.8% in stages I and II, 25% in stages III and IV; p = 0. 006) and in well-differentiated carcinoma (p = 0.001). The existence of adenoma or p53 overexpression did not independently correlate with prognosis. In contrast, the p53 overexpressed group without adenoma showed a worse prognosis than the remaining patients (p = 0. 0006) and this trend was still demonstrable when the groups were compared stage by stage. In ampullary carcinoma, p53 abnormality occurs during malignant transformation from the adenoma and continues during the tumor progression in carcinoma. The clinical prognosis of de novo carcinomas with p53 overexpression was worse than that of the remaining patients.

p53, p16 and RB expression in adenosquamous and squamous cell carcinomas of the stomach

The expression of p53, p16 and RB proteins and their clinicopathologic correlation were investigated in 15 cases of primary gastric adenosquamous carcinoma and 2 cases of squamous cell carcinoma of the stomach. The male to female ratio of the patients was 13:4 and the average age was 55.7 years. None of the cases was early gastric carcinoma, and none of the adenocarcinoma components were of the diffuse or signet ring cell types. Fourteen cases showed metastasis to regional lymph nodes and/or other organs at the time of surgery. The adenocarcinoma component was metastasized to lymph nodes in 12 cases, and both adenocarcinoma and squamous cell carcinoma components were metastasized in three cases. The altered expression of p53 correlated with the advanced stage, but did not correlate with the depth of invasion, lymph node metastasis or recurrence. The altered expression of p16 and RB proteins did not correlate with any of the above clinico-pathologic factors. Both the adenocarcinoma and squamous cell carcinoma components revealed an inverse correlation between the expression pattern of p16 and RB proteins (p < 0.05). This suggests that the two proteins share a role in the carcinogenesis of these tumors. The expression pattern of p53 proteins in the adenocarcinoma and squamous cell carcinoma components was exactly the same in all of the cases. The expression patterns of p16 and RB protein were also identical in most of the cases. The expression patterns of all three proteins in the metastatic lesions were also identical to those in the primary lesions. The fact that the alteration of the three tumor suppressor gene products shares the same pattern suggests that squamous and adenocarcinoma components in the stomach originate from the same or a genetically related clone.

Effects of intracoronary radiation on thrombosis after balloon overstretch injury in the porcine model

BACKGROUND

The main complications of PTCA remain thrombosis and restenosis. Recent studies have demonstrated reduction in the neointimal hyperplasia after intracoronary radiation (IR) with doses of 10 to 25 Gy of ionizing radiation delivered by either beta- or gamma-emitters to injured vessels. The purpose of this study was to examine the effect of ionizing radiation on the thrombosis rate (TR) of injured porcine coronary arteries.

METHODS AND RESULTS

Thirty-four juvenile swine (63 coronary arteries) were subjected to overstretch balloon injury followed by IR with doses of 0 to 18 Gy of either beta- or gamma-radiation. Two weeks after treatment, tissue sections were perfusion-fixed, stained with hematoxylin-eosin and Verhoeff-van Gieson's stain, and analyzed for presence of a thrombus, thrombus morphology, and neointima formation by computer-assisted histomorphometry techniques. Although the overall TR increased dose-dependently from 0 to 18 Gy prescribed dose, luminal thrombi decreased. Thrombus area also decreased with increasing radiation dose, whether assessed at the prescription point or at the luminal surface, which corresponded to decreased intimal area. Furthermore, luminal thrombi present after IR tended to consist mostly of fibrin and thus were less organized than in controls.

CONCLUSIONS

These results suggest that IR induces thrombosis but does not necessarily compromise the lumen. Strategies for reducing TR may further decrease intimal area as well as increasing the safety of this therapy.

p21 promotes ceramide-induced apoptosis and antagonizes the antideath effect of Bcl-2 in human hepatocarcinoma cells

p21, a potent cyclin-dependent kinase inhibitor, has been known to induce cell cycle arrest in response to DNA-damaging agents. Although p21 has been reported to play an important role in the regulation of apoptosis, the postulated role for p21 in apoptosis is still controversial. Previously, we reported that p21 was induced in a p53-independent manner during ceramide-induced apoptosis in human hepatocarcinoma cell lines. In the present study, we investigated the precise role of p21 in ceramide-induced apoptosis in human hepatocarcinoma cells by using a tetracycline-inducible expression system. Overexpression of p21 by itself did not induce apoptosis in p53-deficient Hep3B cells. However, Hep3B/p21 cells were more sensitive to ceramide-induced apoptosis. In these cells, p21 overexpression did not result in G1 arrest. The expression level of Bax was increased in Hep3B/p21 cells treated with ceramide and its expression was more accelerated under the p21-overexpressed condition compared to that of the p21-repressed condition. Overexpression of Bax induced apoptosis in Hep3B cells. On the other hand, the levels of p21 and Bax protein were increased by ceramide in another hepatocarcinoma cell line, SK-Hep-1, while the Bcl-2 protein level was not changed. Overexpression of Bcl-2 not only suppressed apoptosis but also completely prevented induction of p21 and Bax caused by ceramide in SK-Hep-1 cells. Furthermore, overexpression of p21 antagonized the death-protective function of Bcl-2 and upregulated expression of Bax protein. These results suggest that p21 promotes ceramide-induced apoptosis by enhancing the expression of Bax, thereby modulating the molecular ratio of Bcl-2:Bax in human hepatocarcinoma cells.

Saline infusion via local drug delivery catheters is associated with increased neointimal hyperplasia in a porcine coronary in-stent restenosis model

BACKGROUND

Catheter-based local drug delivery at the site of stent implantation has been proposed to reduce in-stent restenosis. We examined whether local delivery itself may cause additional vessel wall injury and negate the potential benefit of local drug delivery in a porcine coronary in-stent restenosis model.

METHODS

Pigs were randomly assigned to no local delivery (controls, n = 10) or local saline infusion (5 ml) using commercially available catheters (n = 39; Dispatch catheter, Microporous Infusion catheter, and InfusaSleeve) prior to oversized (stent:artery ratio 1.2) coronary stent implantation. The amount of in-stent neointima was evaluated 4 weeks later with angiography and histology.

RESULTS

There was no difference in vessel size or stent: artery ratio. However, at follow-up the local saline delivery group had significantly greater diameter stenosis (50 +/- 19% versus 25 +/- 17% in the controls, P < 0.01). Histology revealed similar injury scores but significantly greater neointimal area in the local saline group (3.61 +/- 1.11 mm2 versus 1.96 +/- 0.82 mm2 in the controls, P < 0.01). In a multivariate linear regression analysis, the use of the local delivery catheter was the only independent variable which was positively correlated with the amount of neointima (P = 0.0001).

CONCLUSIONS

In this in-stent restenosis model, catheter-based local saline delivery was associated with significantly increased neointimal hyperplasia. Thus, for local drug delivery to reduce in-stent restenosis, the antiproliferative agent should be potent enough to compensate for the additional neointimal hyperplasia from the infusion itself.