Shohei Kondo

High incidence of allelic loss on chromosome 5 and inactivation of p15^{INK4B} and p16^{INK4A} tumor suppressor genes in oxystress-induced renal cell carcinoma of rats

Ferric nitrilotriacetate induces oxidative damage in renal proximal tubules, a consequence of Fenton-like reaction, that ultimately leads to a high incidence of renal cell carcinoma (RCC) in rats. In order to find common genetic alterations in this oxystress-induced carcinogenesis model, RCCs were produced in F1 hybrid rats between Wistar and Long-Evans strains and genomes were screened for loss of heterozygosity (LOH) with microsatellite polymorphic markers by PCR. Five consecutive markers on chromosome 5 (D5Mgh5, D5Mit9, D5Mgh6, D5Mit11 and D5Mit6) showed LOH in ≥40% of the RCCs. As possible candidate tumor suppressor genes on chromosome 5, p15INK4B and p16INK4A were investigated for genetic alteration and aberrant methylation by Southern blot, PCR/SSCP/sequencing and methylation-specific PCR. Genetic alteration (homozygous or hemizygous deletion with or without point mutation) or aberrant methylation were found in 30.7 and 53.8% of the RCC cases, respectively, which was proportionally associated with the histological nuclear grade and metastatic activity. Our data suggest that inactivation of p15 and p16 genes could be one of the major pathways responsible for oxystress-induced carcinogenesis.

Expression of stress-response and cell proliferation genes in renal cell carcinoma induced by oxidative stress.

Ferric nitrilotriacetate induces oxidative damage in renal proximal tubules that ultimately leads to a high incidence of renal cell carcinoma (RCC) in rats. In search of genes specifically involved in oxystress-induced carcinogenesis, we have applied a modified fluorescent differential display technique to the tumors and an established cell line as well as their non-neoplastic counterparts. We screened approximately 84,000 products. Reverse Northern blotting confirmed differential expression of 20 transcripts, which showed either significant increase, decrease or lack of expression in the RCCs. Five cDNA clones encoded novel products of unknown function. Fifteen cDNA clones were identified by homology search, which included annexin II, Y-box binding protein, ribosomal proteins, heat shock proteins, DNA polymerase, nonmuscle caldesmon (increased); protein tyrosine phosphatase (decreased); selenoprotein P, stromal cell-derived factor 1, intestinal trefoil protein, nicotinamide adenine dinucleotide, reduced form (NADH) dehydrogenase, and insulin-like growth factor binding protein 7 (deleted). Most of the identified genes were associated with stress-response or cellular proliferation. These results suggest that multiple, interactive genetic pathways are involved in carcinogenesis induced by oxidative stress.

Expression of Insulin-Like Growth Factor-2 Can Predict the Prognosis of Human Colorectal Cancer Patients: Correlation with Tumor Progression, Proliferative Activity and Survival

Expression of insulin-like growth factor-2 (IGF-2) has been reported in tissue specimens and cell lines of human colorectal cancers. However, the effects of IGF-2 in colorectal cancer patients are not well known. In this study, IGF-2 staining was performed on tissue samples from 92 patients with colorectal cancer, and the relationship of IGF-2 staining to clinicopathological variables, proliferating cell nuclear antigen (PCNA) staining and patient survival was analyzed. IGF-2 staining was correlated with tumor progression, PCNA staining and patient survival. Our results suggest that IGF-2 plays an important role in tumor progression and that IGF-2 staining is useful as a prognostic factor in colorectal cancer patients.

Protective effect of colored rice over white rice on fenton reaction-based renal lipid peroxidation in rats

Rice has been one of the most important grains. While polished white rice is favored, colored strains of rice, red, or black, have been maintained for religious purposes in Japan. We studied whether feeding of unpolished colored rice instead of white rice ameliorates oxidative renal tubular damage in rats induced by ferric nitrilotriacetate. Whereas renal lipid peroxidation was exacerbated in white rice-fed group in comparison with standard chow group, this exacerbation was not observed in red or black rice-fed groups. These changes were dependent on the proportion of colored rice to standard chow in the diet. Cyanidin 3- O - g - d -glucoside was detectable neither in the serum nor kidney after one week of colored rice diet, but serum protocatechuic acid was significantly increased after black rice diet. There was a generalized decrease in the renal glutathione peroxidase activity in rice diet groups. Renal enzymatic activities of superoxide dismutase, glutathione S -transferase and NAD(P)H quinone reductase were not associated with the levels of lipid peroxidation. However, renal catalase activity was significantly increased in black rice-fed groups. These may partly explain the antioxidative effect. Furthermore, colored strains of rice are rich in proteins. Thus, our data warrants further investigation of the antioxidative effect of colored rice.

Intramuscular metastasis from gastric cancer

Abstract.Skeletal muscle is an uncommon site of hematogenous metastasis of gastric carcinoma. We report here a rare case of gastric carcinoma with multiple intramuscular metastases. Our patient had advanced gastric carcinoma and complained of left gluteal induration with tenderness. Because magnetic resonance imaging (MRI) revealed that the gluteal tumor showed iso-signal intensity on T1-weighted images and high signal intensity on T2-weighted images, with reticulated texture around the tumor, and the patient had advanced gastric carcinoma, we speculated that the tumor was an intramuscular metastatic tumor from primary gastric carcinoma. There were also multiple intramuscular metastatic lesions in both gluteal muscles on the MRI findings that were not detected by physical examination. Therefore, the patient underwent total gastrectomy with combined resection of spleen, with subsequent chemotherapy. Three months after the operation, we excised the gluteal tumor to alleviate the gluteal pain. Histological examinations confirmed that the gluteal tumor was a metastasis from primary gastric carcinoma.

Development of High-grade Renal Cell Carcinomas in Rats Independently of Somatic Mutations in the Tsc2 and VHL Tumor Suppressor Genes

Ferric nitrilotriacetate (Fe‐NTA) induces renal proximal tubular damage that ultimately leads to a high incidence of renal cell carcinoma (RCC) in rats. The RCCs are characterized by 1) high incidence of pulmonary metastasis and peritoneal invasion, 2) high incidence of tumor‐associated mortality and 3) possible involvement of reactive oxygen species in carcinogenesis. The present study investigated the possible role of Tsc2 and VHL tumor suppressor genes in this model. Thirty‐four Fe‐NTA‐induced primary RCCs and 20 other primary or metastatic tumors of rats were searched for genetic alteration in all the coding exons of both genes by polymerase chain reaction‐single‐strand‐conformation polymorphism analysis and sequencing in conjunction with morphological evaluation. In the Fe‐NTA‐induced RCCs, frequency of metastasis or invasion was proportionally associated with the nuclear grade of the tumor (grades 1–3). Only one Fe‐NTA‐induced RCC of grade 1 revealed missense mutations with loss of heterozygosity in exon 10 of the Tsc2 gene (codons 334, GTG (Val) to GCG (Ala), and 336, TAT (Tyr) to CAT (His)). No mutation was found in the VHL gene. The results suggest that 1) high‐grade RCCs can develop in the absence of mutations in the Tsc2 and VHL genes in rats, and that 2) Tsc2 gene somatic mutation can nonetheless be one of the causes of non‐Eker rat RCCs.

Peroxynitrite-mediated stress is associated with proliferation of human metastatic colorectal carcinoma in the liver.

3-Nitrotyrosine (3-NT), a product of peroxynitrite reaction, is abundantly observed in hepatocytes adjacent to human metastatic colorectal carcinoma. To elucidate its biological significance, we undertook to identify nitric oxide (NO)-producing cells and apoptosis under oxidative stress. We observed strong inducible NO-synthase (iNOS) immunoreactivity in the hepatocytes adjacent to metastatic tumor, revealing an identical pattern to 3-NT immunostaining. Furthermore, intense 3-NT immunostaining of hepatocytes was associated with apoptosis whereas carcinoma cells near those hepatocytes presented high proliferating-cell nuclear antigen. Our results suggest that contact of metastatic tumor induces apoptosis in adjacent hepatocytes through peroxynitrite, thus permitting the proliferation of cancer cells.

Pathologic significance of tumor progression in locally recurrent rectal cancer: different nature from primary cancer.

PURPOSE: It has recently been demonstrated that the tumor growth rate is a stronger determinant of survival than the extent of the growth in local recurrence of rectal cancer. We studied which factors controlled the tumor growth rate using modern immunohistochemical methods. METHODS: In 51 patients who underwent extended resection for this condition, paraffin-embedded specimens were examined for 1) tumor angiogenesis by CD31 staining and microvessel counting, 2) apoptosis by terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling staining, and 3) cellular proliferative activity using anti-proliferative cell nuclear antigen antibody. The results were compared with carcinoembryonic antigen doubling time and survival. RESULTS: The five-year survival rate was 20 percent. The postoperative carcinoembryonic antigen doubling time, which was the strongest predictor of survival, correlated highly with proliferative cell nuclear antigen labeling index, but did not correlate with the apoptotic index or microvessel counts. CONCLUSION: Our study shows that cancer cell proliferation rather than apoptosis or angiogenesis is a major determinant of tumor growth rate and survival in patients with locally recurrent rectal cancer.

Spontaneous loss-of-function mutations of the 8-oxoguanine DNA glycosylase gene in mice and exploration of the possible implication of the gene in senescence.

8-Oxoguanine is one of the major premutagenic oxidative base legions in vivo and is suspected to play a crucial role in various pathophysiological processes, such as cancer and aging. Mammalian 8-oxoguanine DNA glycosylase (OGG1) is thought to play a major role in the removal of 8-oxoguanine adducts in vivo. We have identified several inbred mouse strains with a spontaneous mutation, OGG1-R336H or double mutations, OGG1-R304W/R336H. R304W mutation caused a complete loss of OGG1 activity, while the R336H mutation led to disruption of nuclear localization of the enzyme although the activity remained normal. Among the double mutants was SAMP1, which exhibits accelerated senescence and short lifespan. We assessed the possible implication of the mutant OGG1 and 8-oxoguanine in aging utilizing SAMP1 mice. SAMP1 retained 1.5- to 1.9-fold increase in 8-oxoguanine level of hepatic nuclear DNA as compared with normal mice, until at least 12 months of age. A genetic association study, however, indicated that the mutant Ogg1 gene per se is not responsible for the accelerated senescence and short lifespan of SAMP1. Mutant OGG1 may be associated with pathologic conditions in other mouse strains.