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R Oyasu

Publications and source records attributed to R Oyasu.

At least 55 records · Page 3Linked to original sources
PubMed1995

Epithelial tumours of the lower urinary tract in humans and rodents.

Bladder neoplasms that are morphologically similar to those occurring in the human bladder can be induced in rats and mice. Thus, these animal models can provide useful information in elucidating the histogenesis of the human bladder cancer. It is unknown whether human and rodent bladder cancers share similar molecular mechanism(s). There are species-specific differences in the type of neoplastic lesions. In rats, irrespective of the carcinogen used, the lesions tend to be polypoid exophytic masses and invasion is a late event, occurring only after a large dose of carcinogen and after an extended period of observation. On the other hand, mice tend to develop nodular invasive carcinomas readily preceded by the development of CIS. In both species, the neoplasms tend to show squamous differentiation, and metastatic spread is rare. Nevertheless, both species provide a useful model for the assessment of human risk of test chemicals because the principal neoplastic lesions that develop in response to test carcinogens are transitional cell neoplasms. Further study of cases of chemically, induced bladder cancer in rodents is essential to determine the applicability of the mode of action to humans.

Adenocarcinoma↗
PubMed1995

Intraluminal epidermal growth factor affects growth of N-methyl-N-nitrosourea-initiated rat bladder carcinoma.

To confirm our recent finding that epidermal growth factor (EGF) appeared to contribute to the tumor-enhancing effect demonstrated by normal rat urine, we conducted 2 experiments using our heterotopically transplanted rat urinary bladder model. In experiment 1, after a single dose (0.25 mg) of N-methyl-N-nitrosourea (MNU), we intravesically administered EGF (0.05 ml of 500 ng/ml phosphate-buffered saline) once a week for 30 weeks. Instillation of EGF induced a significantly larger number of tumors than did instillation of the vehicle (P = 0.03). EGF without MNU initiation did not induce tumors. In experiment 2, 2 groups received instillation of killed Escherichia coli (5 x 10(8) cells)/0.5 ml phosphate-buffered saline once a week for 4 weeks to expand the MNU-initiated cell population. Subsequent EGF treatment significantly increased the incidence of tumors (P = 0.01). In the groups which did not receive killed E. coli, EGF treatment induced a significantly higher number of tumors than did vehicle treatment (P < 0.001). All of the tumors were low-grade, superficial transitional cell carcinomas. These observations indicate that EGF acts as a growth-stimulating factor on dormant neoplastic cells and thereby increases the number of tumors.

Animals↗
PubMed1995

p53 gene mutations in human urothelial carcinomas: analysis by immunohistochemistry and single-strand conformation polymorphism.

We examined 60 cases of human urothelial carcinomas (27 superficial and 33 deeply invasive) for the frequency of p53 gene mutations. Forty-two cases were analyzed by both the immunohistochemical and the single-strand conformation polymorphism (SSCP) methods, and the remaining 18 cases were assayed by SSCP alone. For the latter assay, exons 4 to 8 were amplified by polymerase chain reaction, and the amplified nucleotides were analyzed for the evidence of mutations by gel electrophoresis. When mobility shift was observed, direct nucleotide sequencing was performed to determine mutation sequence. Three superficial and eight deeply invasive carcinomas demonstrated evidence of mutations. Mutations involved various codons randomly. The fact that all tumors with mutations of the p53 gene except for one were of high nuclear grade (grade III) suggests that p53 mutation is associated with the progression of bladder cancers. Our results indicate that SSCP is a sensitive screening assay for detecting gene mutations. Immunohistochemical analysis is also a sensitive method but may yield false positive as well as false negative results.

Adult↗
PubMed1994

Persistence of carcinogen-altered cell population in rat urothelium which can be promoted to tumors by chronic inflammatory stimulus.

Chronic inflammation of the urinary tract is a significant risk factor for the development of urinary bladder cancer in man. Previously we have shown that acute and chronic inflammation induced by repeated intravesical instillation of killed Escherichia coli (KEC) strikingly enhanced N-methyl-N-nitrosourea (MNU)-initiated bladder carcinogenesis in our heterotopically transplanted rat urinary bladder model. We conducted the present study to determine whether delayed onset of KEC treatment can still enhance carcinogenesis of the MNU-initiated urothelium and whether continuous KEC treatment is necessary for the development of tumors. After the initiation of carcinogenesis in heterotopically transplanted bladders by the instillation of a single dose (0.25 mg) of MNU, animals were divided into several groups, for which weekly KEC treatment (5 x 10(8) cells suspended in 0.5 ml of phosphate-buffered 2.1% NaCl solution) was begun 1, 5, and 18 weeks later and continued until termination of the experiment at 31 weeks. In addition, animals received 4-week KEC treatment, which was started 1 or 5 weeks after MNU administration. Treatment with KEC alone or MNU alone induced few tumors. Maximal tumor development was demonstrated in the group receiving KEC treatment continuously throughout the experimental period. Delaying the onset of continuous KEC treatment by 4 weeks resulted in a significant decrease in the number of tumors (P = 0.006). However, a substantial number of tumors were induced even when KEC treatment was delayed as many as 18 weeks, as compared to tumor development in the group receiving MNU only (P = 0.007). The tumor volume (size) was not different between continuous and short-term KEC treatment groups. We conclude that (a) although a large number of cells undergo promutagenic DNA damage by a single dose of MNU, the amounts are reduced quickly during the subsequent 4 weeks; but that (b) a substantial number of genetically altered cells remain for a long time and can be promoted to tumors when stimulated by a chronic inflammatory stimulus; and that (c) the duration of KEC treatment determines the number, but not the volume, of tumors.

Animals↗
PubMed1994

In vitro and in vivo acceleration of the neoplastic phenotype of a low-tumorigenicity rat bladder carcinoma cell line by transfected transforming growth factor-alpha.

We conducted an experiment to determine whether expression of transforming growth factor-alpha (TGF-alpha) enhances tumorigenicity in a low-tumorigenicity rat bladder carcinoma cell line and whether it is sufficient to induce a tumorigenic phenotype in a nontumorigenic rat bladder cell line. D44c cells (which are nontumorigenic) were derived from a minute nodule from a bladder treated with N-methyl-N-nitrosourea (MNU); G1-200 cl-17 cells (which have low tumorigenicity) were isolated from D44c cells exposed to MNU in vitro. Neither cell line expressed TGF-alpha mRNA. The cells were cotransfected with pSV2neo and pSR alpha-rTGF-alpha. The latter plasmid contains the rat TGF-alpha cDNA under the transcriptional control of the SR alpha promoter. In the low-tumorigenicity G1-200 cl-17 cells, the expression of TGF-alpha mRNA and the subsequent synthesis of TGF-alpha protein activated epidermal growth factor receptors (EGFRs) and markedly enhanced tumorigenicity in nude mice (i.e., shortened the latency period before tumor appearance, accelerated the rate of growth, and increased the size of the tumors) as well as anchorage-independent growth in vitro. In nontumorigenic D44c cells, however, transfected TGF-alpha did not induce either anchorage-independent growth or tumorigenicity in nude mice, in spite of overexpression of EGFR mRNA and the constitutive expression of c-jun and junB mRNA. These results suggest that the increased signal transduction mediated by TGF-alpha enhanced tumorigenicity in a cell that was already tumorigenic but was not sufficient to induce tumorigenicity in a nontumorigenic cell.

Animals↗
PubMed1994

Cytotoxic effect of a fusion protein from transforming growth factor alpha and Pseudomonas exotoxin on rat and human bladder carcinoma cells in vitro.

A protein formed by fusion of transforming growth factor alpha with Pseudomonas exotoxin (TGF alpha-PE40) has been shown to have the ability to kill or inhibit the growth of several carcinoma cell lines. This study was designed to evaluate the in vitro cytotoxic effects of TGF alpha-PE40 on rat and human bladder carcinoma cell lines with different biological potential, and normal rat urothelial cells. The rat cell lines used were D44c, LMC19, and MYU3L, which were established in our laboratory. Human cell lines used were RT4, T24, and 253J. As a normal control, we used the first-passage culture of normal rat bladder urothelium (RU-P1). We examined the number and affinity of epidermal growth factor receptors (EGFR) in these cells, the ability of TGF alpha-PE40 to bind EGFR, and the cytotoxic effect of TGF alpha-PE40 and PE40. Rat cell lines, D44c, LMC19, and MYU3L (EGFR = 4.9 x 10(3)-11.4 x 10(3)/cell) had ED50 values (the concentration of TGF alpha-PE40 needed to reduce the viable cell population by 50%) of 180 pM, 540 pM and 6000 pM respectively; for cI (the concentration required to achieve complete inhibition of growth under continuous serum stimulation) TGF alpha-PE40 concentrations of 10(4) pM, 10(4) pM and higher than 10(4) pM respectively were required. Human cell lines, RT4, T24, and 253J (EGFR = 32 x 10(3)-126 x 10(3)/cell) had ED50 values of 20 pM, 66 pM, and 330 pM respectively and T24 showed cI values of 10(3) pM. RU-P1 (EGFR = 92.6 x 10(3)/cell) had the highest ED50 value of 8000 pM. These data indicate that the susceptibility to TGF alpha-PE40 does not always depend on the number of EGFR, that cells having a relatively small number of EGFR respond well to TGF alpha-PE40, and that normal urothelial cells are more resistant to TGF alpha-PE40 than are cancer cells. The differential effect of TGF alpha-PE40 on normal and neoplastic cells provides a rational basis for its use in vivo to control tumor growth.

ADP Ribose Transferases↗
PubMed1994

The clinical and pathological manifestations of renal tumors in von Hippel-Lindau disease.

The protean nature of renal lesions in von Hippel-Lindau disease has made surgical management difficult. To develop a sensible surgical approach the pathological and clinical manifestations of renal involvement in von Hippel-Lindau disease patients were defined. A total of 87 lesions in 9 kidneys from 6 patients with von Hippel-Lindau disease was examined for size, presence of renal cell carcinoma, cystic or solid qualities and local invasion. There was no correlation between the size of the lesion and renal cell carcinoma. All 44 benign lesions were cystic, while 35% (15 of 43) of malignant lesions were cystic and 65% (28 of 43) were solid. All 9 locally invasive tumors were solid. The distribution of lesions in our patients was compared to the findings in 138 cases we collected from the literature. The 3 patterns of clinical presentation recognized were solitary, multiple and diffuse. We recommended that all lesions, cystic or solid, be excised at the time of nephron sparing surgery, with a wider margin for solid lesions, and that nephron sparing surgery should be reserved for patients with cystic and small solid lesions, with radical nephrectomy being preferred for patients with diffuse disease.

Adult↗
PubMed1994

Reversed seromuscular flaps in the urinary tract in dogs.

Reversed seromuscular flaps of ileum and standard bowel replacement procedures were performed in 16 dogs to evaluate their potential to decrease the likelihood of recognized complications in cases of standard bowel replacement. Of 12 dogs augmentation cystoplasty was done in 6 and ureteral replacement was done in 6. In each group 4 procedures were performed using reversed seromuscular flap, while the remaining 2 were done in the conventional manner (controls). All flap animals had partial to full re-epithelialization with transitional cells but they also had gross and microscopic evidence of flap contraction at the end of 6 months. In the flap augmentation group intravesical pressure measured preoperatively at bladder volumes of 30 cc and 60 cc averaged 25.8 and 45.8 mm. Hg compared to sacrifice pressures of 56.7 and 80.8 mm. Hg. Monthly serum blood urea nitrogen measurements were lower in reversed seromuscular flap animals compared to controls. An additional 4 dogs were studied to help elucidate the etiology of graft contraction, of which 2 underwent reversed seromuscular flap enterocystoplasty with no mucosal stripping while 2 had a procedure exposing intact intestinal serosa to the lumen of the bladder and urine. All of these animals demonstrated good re-epithelialization of the serosal surface with transitional cells as well as little or no evidence of flap fibrosis or contraction. Our results demonstrate that the use of reversed seromuscular flaps in the urinary tract in dogs results in good re-epithelialization of the serosal surface with transitional cells but also flap contraction. This fibrosis and scarring process is largely due to the trauma of mucosal stripping and not urine contact.

Animals↗
PubMed1994

Evaluation of polydimethylsiloxane as an alternative in the endoscopic treatment of vesicoureteral reflux.

Endoscopic correction of vesicoureteral reflux is an attractive alternative to open repair. In terms of effectiveness and long-term successful results polytetrafluoroethylene (Polytef) is the most reliable injectable product. However, legitimate concerns regarding particle migration still exist for polytetrafluoroethylene. Polydimethylsiloxane (Macroplastique) was evaluated as an alternative to polytetrafluoroethylene. Seven mongrel female dogs underwent endoscopic suburothelial injections of 0.35 to 0.50 cc polydimethylsiloxane paste by the O'Donnell technique to a unilateral nonrefluxing ureteral orifice. To facilitate migratory surveillance the paste was mixed with 57carbon monoxide radiolabeled 80 microns. microspheres and injected in 5 of the 7 animals. Animals were sacrificed at 1, 3 and 6-month intervals. All major organs were retrieved and processed. After intensive histological evaluation the remaining tissue underwent dissolution and centrifugation in sodium hypochlorite. The resulting insoluble pellet was further analyzed. In dogs injected with radiolabeled paste tissue samples and insoluble pellets of each organ system were analyzed for gamma counts. Smears of the insoluble pellets of all animals were examined on light and phase contrast microscopy. At autopsy no gross abnormalities were noted. Tissue reaction at injection sites revealed a well encapsulated foreign body reaction with predominantly giant cells, fibroblasts and collagen deposition. Limited local migration of polydimethylsiloxane particles into the periureteral lymphatics of 1 animal sacrificed at 1 month was noted and a single particle visually indistinguishable from polydimethylsiloxane also was found within the splenic capsule. The endoscopic procedure in this animal was complicated in that 2 separate injections were required and histological evaluation confirmed that the injections were performed uniquely deep into the bladder muscularis. Radioactive counts and dissolution of all major organ systems demonstrated no migration in the remaining 6 animals. Endoscopic subureteral injection of polydimethylsiloxane is technically feasible, and it may prove to be biocompatible and without risk of distant migration if injected correctly.

Animals↗
PubMed1994

Touch preparation cytological evaluation of radical prostatectomy specimens.

The failure of current histological techniques to predict local failure and disease progression after radical prostatectomy is supported by substantial evidence. Moreover, the characterization of histological findings is hampered by the lack of uniform interpretation. We report a prospective study of 92 patients undergoing radical prostatectomy for clinical stages A and B prostate cancer in which the technique of touch preparation cytological analysis of surgical margins is compared to the standard histological approach. We evaluated 47 pathological stage B, 43 stage C and 2 stage D specimens. Specimens initially assigned to pathological stage B were upstaged to stage C on review by 1 blinded pathologist in 19 of 65 cases (29%). Overall, 15 of 47 histological stage B specimens (32%), 20 of 43 histological stage C specimens (47%) and 2 of 2 histological stage D specimens (100%) had malignant cells identified on the margins by touch preparation cytology. Postoperative mean followup of 7 months (range 0.4 to 26) revealed that 7 of 14 nonstage D cancer patients (50%) with elevated serum prostate specific antigen levels had positive cytology results, including 1 with histologically confirmed organ-confined disease. Among the stage C specimens cytology was more likely to be positive if there was concomitant seminal vesicle invasion. Correlation of this information with eventual patient course during the long term will be necessary to assess its role in patient management.

Aged↗
PubMed1994

Human chorionic gonadotropin beta-subunit synthesis by undifferentiated urothelial carcinoma with syncytiotrophoblastic differentiation.

An undifferentiated deeply invasive ureteral carcinoma with syncytiotrophoblastic differentiation was analyzed for the synthesis of human chorionic gonadotropin beta-subunit by immunohistochemistry and Northern blot analysis. Human chorionic gonadotropin beta-subunit was localized immunohistochemically to syncytiotrophoblastic cells and scattered mononuclear tumor cells. Human chorionic gonadotropin beta-subunit gene was expressed at a high level by Northern blot analysis. To our knowledge, this is the first report demonstrating the synthesis of human chorionic gonadotropin beta-subunit at the transcriptional level in a urothelial carcinoma.

Aged↗
PubMed1994

In vitro radiation-induced neoplastic progression of low-grade uroepithelial tumors.

Recent interest has focused on the identification of molecular genetic mechanisms in multistep neoplastic transformation. In vitro exposure of simian virus 40 (SV40)-immortalized human uroepithelial cells (SV-HUC) that are environmentally relevant to bladder carcinogens has been shown to produce tumorigenic transformation, as assessed by the ability of cells exposed to a carcinogen to form xenograph tumors with heterogeneous cancer phenotypes ranging from very aggressive, invasive high-grade carcinomas to superficial low-grade indolent tumors. In addition, exposure of a low-grade indolent tumor generated in the SV-HUC system, MC-T11, to the same carcinogens results in neoplastic progression as assessed by the production of high-grade aggressive cancers. In the present study, we show neoplastic progression of MC-T11 after in vitro exposure to a single dose of 6 Gy X rays. In addition, we show that the chromosome deletions, including losses of 4q, 11p, 13q and 18, observed in these radiation-induced tumors are similar to those observed in carcinogen-induced tumors, thus supporting the hypothesis that the experimental cell system, not the transforming agent, dictates the genetic losses required for tumorigenic transformation and progression.

Animals↗
PubMed1993

Differential expression of keratin 5 gene in non-tumorigenic and tumorigenic rat bladder cell lines.

In this study, we attempted to find a gene or genes which were differentially expressed between a non-tumorigenic rat bladder cell line and a highly tumorigenic/metastatic bladder carcinoma cell line that was derived from the former after treatment in vitro with N-methyl-N-nitrosourea. We cloned a rat keratin 5 cDNA by a differential hybridization technique and found that all of the non-tumorigenic cells (7/7) and normal bladder tissue expressed keratin 5, but most of the tumorigenic cells (8/10) did not express keratin 5. Furthermore, in a spontaneously transformed cell line, keratin 5 expression was lost during the transformation process. These results suggest that loss of keratin 5 expression is closely associated with acquisition of a tumorigenic phenotype by rat bladder non-tumorigenic cells.

Animals↗
PubMed1993

Effect of epidermal growth factor and transforming growth factor beta 1 on growth and invasive potentials of newly established rat bladder carcinoma cell lines.

We established 5 rat bladder cell lines (MYU3L, MYU4, MYU6s, MYKU1L and MYP3). EGF stimulated DNA synthesis of all the cells in monolayer culture, regardless of the number of EGF receptors. In soft agar, only MYU3L formed colonies, and EGF enhanced their growth. However, EGF did not induce the other cells to grow in soft agar. In contrast, TGF-beta 1 inhibited the growth of the cells, but a tumorigenic cell and the cells which were established from large in vivo tumors were more resistant than the others to TGF-beta 1. We tested the effect of growth factors on the invasive potential of MYP3 cells (non-tumorigenic), MYU3L cells (tumorigenic/highly invasive but not metastatic) from newly established cell lines, and another metastatic cell line, LMC19. MYP3 expressed only a trace amount of 92-kDa gelatinase (MMP-9), whereas MYU3L expressed interstitial collagenase (MMP-1) and MMP-9, and LMC19 expressed 72-kDa gelatinase (MMP-2) and MMP-9. The release of MMP-2 in LMC19 was stimulated by TGF-beta 1, but EGF had no effect on the release of any MMPs in either type of cells. These observations suggest that EGF acted as a mitogen on all the cells tested, but did not enhance the malignant phenotype. Further, the loss of responsiveness to the suppressive effect of TGF-beta 1 may be an important step toward a malignant phenotype. Some of malignant tumors may utilize TGF-beta 1 for enhancing their invasive and metastatic potential.

Animals↗
PubMed1993

Enhancement of rat urinary bladder tumorigenesis by lipopolysaccharide-induced inflammation.

Chronic inflammation of the urinary tract is a significant risk factor for the development of urinary bladder cancer in humans. We previously demonstrated that weekly treatment with killed Escherichia coli enhanced rat urinary bladder tumorigenesis initiated by the carcinogen N-methyl-N-nitrosourea. We conducted the present study to determine whether lipopolysaccharide (LPS), a major cell wall component of E. coli, had a tumor-enhancing effect. LPS was instilled twice a week at three doses (100, 1.0, and 0.01 microgram/ml) into heterotopically transplanted rat urinary bladders which were treated with a single low dose (0.25 mg) of N-methyl-N-nitrosourea or vehicle. Rats treated with 100 micrograms/ml of LPS showed a significant increase in the incidence and number of tumors in the bladders pretreated with N-methyl-N-nitrosourea. Treatment with LPS alone did not induce tumors. The enhancing effects were associated with a marked increase in the numbers of polymorphonuclear leukocytes and an increase in the H2O2 concentration in the bladder lumen. Oxidative stress by reactive oxygen intermediates and a proliferative response of the carcinogen-exposed urothelium to the inflammatory stimulation appeared to play a significant role in tumor enhancement by LPS.

Animals↗
PubMed1993

Immunohistochemical localization of transforming growth factor alpha in the major salivary glands of male and female rats.

The three major salivary glands of normal male and female Fischer 344 rats of different ages were examined for the localization of epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) by immunohistochemical staining. EGF was demonstrated only in the granulated convoluted tubule (GCT) cells of the submandibular gland, the results confirming the previous reports, and most abundantly in adult males and pregnant females. TGF alpha stain was localized in all three glands and was found throughout the entire duct system, excluding acinar cells. The myoepithelial cells of the sublingual gland were also reactive with the TGF alpha antibody. The specificity of the staining was confirmed by negative staining reaction with the absorbed antibody and by radio-immunoassay and Western blot methods. This is the first report describing the presence of TGF alpha in the rat salivary glands.

Animals↗