Role of urothelial cells in BCG immunotherapy for superficial bladder cancer

Intravesical instillation of Bacillus Calmette-Guérin (BCG) is used for the treatment of superficial bladder cancer, both to reduce the recurrence rate of bladder tumour and to diminish the risk of progression. Since its first therapeutic application in 1976, major research efforts have been directed to decipher the exact mechanism of action of the BCG-associated antitumour effect. Bacillus Calmette-Guérin causes an extensive local inflammatory reaction in the bladder wall. Of this, the massive appearance of cytokines in the urine of BCG-treated patients stands out. Activated lymphocytes and macrophages are the most likely sources of these cytokines, but at present other cellular sources such as urothelial tumour cells cannot be ruled out. Bacillus Calmette-Guérin is internalised and processed both by professional antigen-presenting cells and urothelial tumour cells, resulting in an altered gene expression of these cells that accumulates in the presentation of BCG antigens and secretion of particular cytokines.     

p53 deficiency provokes urothelial proliferation and synergizes with activated Ha-ras in promoting urothelial tumorigenesis

Mutation and deletion of the p53 tumor suppressor gene are arguably the most prevalent among the multiple genetic alterations found in human bladder cancer, but these p53 defects are primarily associated with the advanced diseases, and their roles in bladder tumor initiation and in synergizing with oncogenes in tumor progression have yet to be defined. Using the mouse uroplakin II gene promoter, we have targeted into urothelium of transgenic mice a dominant-negative mutant of p53 that lacks the DNA-binding domain but retains the tetramerization domain. Urothelium-expressed p53 mutant binds to and stabilizes the endogenous wild-type p53, induces nuclear abnormality, hyperplasia and occasionally dysplasia, without eliciting frank carcinomas. Concurrent expression of the p53 mutant with an activated Ha-ras, the latter of which alone induces urothelial hyperplasia, fails to accelerate tumor formation. In contrast, the expression of the activated Ha-ras in the absence of p53, as accomplished by crossing the activated Ha-ras transgenic mice with the p53 knockout mice, results in early-onset bladder tumors that are either low-grade superficial papillary or high grade in nature. These results provide the first in vivo experimental evidence that p53 deficiency predisposes the urothelium to hyperproliferation, but is insufficient for bladder tumorigenesis; that the mere reduction of p53 dosage, as produced in transgenic mice expressing the dominant-negative p53 or in heterozygous p53 knockouts, is incapable of synergizing with Ha-ras to induce bladder tumors; and that the complete loss of p53 is a prerequisite for collaborating with activated Ha-ras to promote bladder tumorigenesis.     

肿瘤骨桥蛋白相关信号通路研究进展

骨桥蛋白(OPN)为一种分泌型、趋化因子样、糖基化的细胞外基质结合蛋白,与其主要受体整合素和CD44结合,参与调节体内多器官多组织的病理生理过程.OPN相关的信号转导在肿瘤发生、演进过程中扮演重要的角色,OPN有望成为肿瘤生物学治疗的新靶点.     

Lack of correlation between rare Ha-ras alleles and urothelial cancer in Japan

Restriction fragment length polymorphism (RFLP) of Ha-ras gene was surveyed by Southern blot analysis in leukocyte DNA from 55 normal individuals and 58 urothelial cancer patients in Japan. Three common alleles and 4 rare alleles were classified. The frequency of common alleles in normal Japanese individuals differed from that in Caucasians previously reported; a 7.2-7.5-kb BamHI fragment of common allele was not observed in Japanese individuals. No significant increase in frequency of the rare Ha-ras allele was observed in the group of cancer patients. Moreover, no significant difference in frequency was observed for the 3 common alleles. Tumor DNA was compared with leukocyte DNA in 30 urothelial cancer patients: in 3 of 8 cases with heterozygous Ha-ras locus, decreased intensity of one band, indicating partial loss of one allele in tumor DNA, was observed. In 3 tumors with either deletion of one Ha-ras allele or a rare Ha-ras allele, expression of Ha-ras gene was examined by Northern blot analysis. Such genetic alterations did not always result in a marked increase in Ha-ras expression. These data suggest that these genetic alterations are not directly related to Ha-ras expression, and that RFLP of Ha-ras gene is not a useful genetic marker for urothelial cancer. On the other hand, deletion of one Ha-ras allele was observed in 1 of 5 cases of bladder cancer and in 2 of 3 cases of renal pelvic cancer, suggesting that that deletion may be important in the development of urothelial cancer.     

MAPK信号转导通路在肿瘤化疗耐药中的作用

丝裂原活化蛋白激酶(MAPK)信号转导通路是调节细胞增殖和凋亡的重要通路.最近研究发现,MAPK信号转导通路可能参与肿瘤化疗耐药,其作用机制可能是调控耐药相关基因的表达,通过对该通路的干预可以提高肿瘤的化疗敏感性,从而逆转化疗耐药.     

Association of cyclooxygenase-2 immunoreactivity with tumor recurrence and disease progression in superficial urothelial bladder cancer

AIMS AND BACKGROUND: The main characteristic of urothelial bladder cancer is a clear predisposition to recurrence and disease progression. The aim of this study was to assess the possible relationship between cyclooxygenase-2 (COX-2) immunoreactivity in superficial urothelial bladder carcinoma and tumor grade, stage, number of recurrences and clinical disease progression. METHODS: In this prospective study 70 consecutive patients who underwent transurethral resection for superficial urothelial bladder cancer were included. Tumor slides were immunohistochemically stained for COX-2, and COX-2 immunoreactivity in tumor and inflammatory stromal cells was categorized as negative or mildly, moderately or strongly positive. Patients were followed up for 2 years, and during this period the possible association of COX-2 immunoreactivity with tumor stage and grade, number of recurrences and progression of disease was evaluated. RESULTS: COX-2 immunoreactivity in tumor cells was found in 57 (81.4%) patients and did not correlate with tumor grade, stage of disease, number of recurrences, and progression of disease. COX-2 immunoreactivity in inflammatory cells was found in 16 of the 57 patients with COX-2 positive tumors, and was significantly related to the number of recurrences, time to appearance of the first recurrence, and disease progression. CONCLUSIONS: COX-2 immunoreactivity in inflammatory stromal cells adjacent to the COX-2-positive tumor might be useful in clinical practice for selection of patients with a high risk of tumor recurrence and disease progression.     

Spontaneous Ha-ras gene activation in cultured primary murine keratinocytes: consequences of Ha-ras gene activation in malignant conversion and malignant progression

The activation of the c-Ha-ras gene and its contribution to the tumorigenic phenotype were examined in cultured mouse keratinocytes and squamous tumors using transfection into NIH 3T3 cells and nucleic acid hybridization. When normal keratinocytes were cultured in medium with 0.05 mM Ca2+ (low Ca2+ medium), many cells died within 2-3 wk, while others formed rapidly growing foci that could be subcultured. These rapidly growing cells produced benign tumors when grafted to nude mice and possessed a heterozygous mutation in the c-Ha-ras gene with an A----T transversion in codon 61. Fibroblast-conditioned low Ca2+ medium prevented cell death, focus formation, c-Ha-ras gene mutation, and tumorigenicity. Thus, suboptimal culture conditions favored a spontaneous mutation in codon 61 of the c-Ha-ras gene of keratinocytes. When a v-Ha-ras gene was introduced into normal keratinocytes by a replication-defective retrovirus, the recipient cells produced papillomas in vivo, and after 2 mo, 60% of the tumors converted to squamos cell carcinomas. None of the 22 converted tumors had an endogenous c-Ha-ras gene mutation at codon 61. However, the A----T transversion mutation developed when these carcinoma cells were cultured in low Ca2+ medium but not in fibroblast-conditioned medium. Cells with both an exogenous v-Ha-ras and an activated c-Ha61-ras gene produced undifferentiated, rapidly lethal carcinomas, while cells with only v-Ha-ras maintained the squamous carcinoma phenotype. Undifferentiated carcinomas also developed when the v-Ha-ras gene was introduced into papilloma cells with a chemically induced endogenous c-Ha61-ras gene mutation. These results suggest that mutation in the c-Ha-ras gene can contribute to initiation, malignant conversion, and malignant progression in skin carcinogenesis, and gene dosage may determine the phenotype expressed.     

磷脂酰肌醇3激酶-蛋白质丝氨酸苏氨酸激酶途径与肿瘤的关系

磷脂酰肌醇3激酶（PI3K）-蛋白质丝氨酸苏氨酸激酶（Akt）途径是细胞内重要的信号传导途径,在细胞增殖分化中起重要作用。PI3K-Akt途径的失调控对于多种肿瘤的发生是一种刺激信号,途径中任何激酶表达的异常都可能诱导肿瘤的发生。现综述PI3K-Akt途径中PI3K、Akt、磷脂酰肌醇依赖性蛋白激酶（PDK）、与张力蛋白同源的第10号染色体上丢失的磷酸酶基因（PTEN）在肿瘤发生发展中的作用。     

Role of the Ha-ras (RasH) oncogene in mediating progression of the tumor cell phenotype (review)

Recent experimental evidence indicates that the c-Ha-ras (rasH) oncogene may be causally involved in the etiology and evolution of specific human neoplasms. In addition, cultured cells transformed by the rasH oncogene can induce both a tumorigenic and a metastatic phenotype when expressed in appropriate cultured cells. To begin to define the molecular and biochemical mechanism(s) by which the rasH oncogene induce their effects on expression of the transformed state we have employed a cloned rat embryo fibroblast (CREF) cell line. Transformation of CREF cells with wild-type 5 adenovirus (Wt) results in transformed cells which display anchorage-independence and an increased saturation density in monolayer culture, but are non-tumorigenic in both athymic nude mice and syngeneic Fischer rats. In contrast, when CREF cells are transformed with mutant type 5 adenoviruses, such as H5hrl, or the ElA transforming gene from hrl (0-4.5), tumors are induced in both nude mice and syngeneic rats. However, hrl (0-4.5)-transformed CREF cells are not metastatic following intravenous injection into the tail vein of syngeneic rats. Insertion of an activated T24 rasH oncogene or a wild-type v-rasH oncogene into CREF, wt-transformed CREF or hrl (0-4.5)-transformed CREF cells results in acquisition of a metastatic phenotype by these cells. A mutant v-rasH oncogene (mutant 116K), which is defective in GTP binding and the induction of transformation of NIH 3T3 cells, does not induce transformation in CREF cells, but it can progress wt-transformed CREF cells to a tumorigenic-non-metastatic state. Employing this model system which displays well-defined and stable stages in the tumor cell progression lineage, we have analyzed the potential role of changes in the phosphatidylinositol (PI) cycle and phospholipase A2 (PLA2) enzyme activity during progression to a tumorigenic and metastatic phenotype. An increase in PI cycle intermediates (primarily inositol triphosphate; IP3) were observed only in the wt-transformed and hrl (0-4.5)-transformed CREF cell lines transfected with the rasH oncogene. In the case of PLA2, all rasH-transformed CREF cell lines displayed increased activity. In contrast, CREF cells transformed only by Ad5 (Wt or hrl (0-4.5)) or the 116K v-rasH oncogene did not display increased PLA2 activity similar to that observed in rasH transfected cells. Since one important metabolite generated by PLA2 is arachidonic acid, which is converted into prostaglandins and leukotrienes by cyclooxygenase or lipooxygenase, respectively, the levels of prostaglandin E2 (PGE2) in the various cell lines were monitored.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ha-ras codon 12 mutation in papillary tumors of the urinary-bladder - a retrospective study

This report concerns the retrospective examination of low grade, low stage (Ta/T1) bladder tumors for the Ha-ras codon 12 G-->T mutation. The patients studied had a minimum of 5 years follow-up and were grouped into 3 categories: (i) patients with no recurring tumors, (ii) patients with recurring Ta/T1 tumors and (iii) patients who subsequently developed high grade, high stage tumors. A heminested, non-isotopic, allele-specific polymerase chain reaction (PCR) amplification assay was used. The codon 12 G-->T mutation was found in 10/27 specimens from patients with non-recurring Ta/T1 tumors; in 11/27 initial and 12/23 recurring Ta/T1 tumors, and in 5/8 initial Ta/T1 lesions and 8/12 subsequently developed high grade/stage tumors. Although there was no correlation between disease recurrence and mutation, these results indicate that a relatively large proportion of patients with Ta/T1 tumors of the bladder have cells with the Ha-ras codon 12 G-->T substitution.     

Histomorphometry and pattern recognition analysis of urothelial papillary lesions

The authors report the results of the grading of urothelial papillary carcinoma using histomorphometry and pattern recognition analysis. Features concerning nuclear area, the nuclear roundness factor and inclination angle were measured in 38 cases of urothelial papillary carcinomas. The relative frequency distribution showed overlapping among the grades with a reduction in the practical significance of histomorphometry. To overcome this problem, the pattern recognition analysis was applied. It was found that mean nuclear area, mean roundness factor and percentages of round and horizontal nuclei represent the optimal discriminating set of the subsequent steps in the malignant urothelial transformation.     

Role of aberrant PI3K pathway activation in gallbladder tumorigenesis

The PI3K/AKT pathway governs a plethora of cellular processes, including cell growth, proliferation, and metabolism, in response to growth factors and cytokines. By acting as a unique lipid phosphatase converting phosphatidylinositol-3,4,5,-trisphosphate (PIP3) to phosphatidylinositol-4,5,-bisphosphate (PIP2), phosphatase and tensin homolog (PTEN) acts as the major cellular suppressor of PI3K signaling and AKT activation. Recently, PI3K mutations and loss/mutation of PTEN have been characterized in human gallbladder tumors; whether aberrant PTEN/PI3K pathway plays a causal role in gallbladder carcinogenesis, however, remains unknown. Herein we show that in mice, deregulation of PI3K/AKT signaling is sufficient to transform gallbladder epithelial cells and trigger fully penetrant, highly proliferative gallbladder tumors characterized by high levels of phospho-AKT. Histopathologically, these mouse tumors faithfully resemble human adenomatous gallbladder lesions. The identification of PI3K pathway deregulation as both an early event in the neoplastic transformation of the gallbladder epithelium and a main mechanism of tumor growth in Pten heterozygous and Pten mutant mouse models provides a new framework for studying in vivo the efficacy of target therapies directed against the PI3K pathway, as advanced metastatic tumors are often addicted to “trunkular” mutations.     

IMP3 predicts aggressive superficial urothelial carcinoma of the bladder

PURPOSE: In this study, we investigated whether an oncofetal protein, IMP3, can serve as a new biomarker to predict progression and metastasis of early-stage urothelial carcinoma of the bladder. EXPERIMENTAL DESIGN: The expression of IMP3 in 242 patients with primary superficial bladder urothelial carcinoma and metastatic urothelial carcinoma was evaluated by immunohistochemistry. Patients with primary superficial urothelial carcinoma of the bladder were further investigated by use of survival analysis. RESULTS: Twenty percent (42 of 214) of primary superficial urothelial carcinomas and 93% (26 of 28) of metastatic urothelial carcinomas expressed IMP3. Kaplan-Meier plots and log-rank tests showed that patients with IMP3-positive tumors had a much lower progression-free survival (P = 0.0002) and disease-free survival rate (P = 0.0067) than did those with IMP3-negative tumors. The 5-year progression-free and disease-free survival rates were 91% and 94% in IMP3-negative patients versus 64% and 76% in IMP3-positive patients, respectively. Sixty percent of IMP3-positive patients with superficial invasive urothelial carcinoma at initial diagnosis went on to develop metastases, whereas no metastasis was found in IMP3-negative patients (P = 0.0017). In the multivariable Cox analysis, patients with IMP3 expression in their superficial urothelial carcinomas subsequently developed invasive tumors or metastasis at a rate that was about five times greater than cases without expression of IMP3 adjusting for other well-known clinical variables (tumor stage and grade, etc.). CONCLUSIONS: Our findings indicate that IMP3 is an independent prognostic marker that can identify a group of patients with a high potential to develop progression and who might benefit from early aggressive therapy.     

Role of tumor necrosis factor in macrophage activation and tumoricidal activity

Tumor necrosis factor (TNF)-sensitive (LM) and -insensitive (P815) target cell lines were used to examine the role of TNF in both the activation and lytic phases of macrophage-mediated lysis. LM cells were lysed spontaneously by thioglycolate-elicited macrophages in an 18-h assay (media or activating agents added with targets) or 36-h assay (macrophages cultured with media or activating agents for 18 h, washed, and targets added for a subsequent 18 h). In contrast, P815 cells were lysed only in the 36-h assay by macrophages exposed to appropriate activation signals. Using antibody to murine TNF, it was shown that lysis of LM cells but not P815 cells was TNF mediated. The addition of lipopolysaccharide (LPS) to the 18-h assay resulted in augmented LM killing. This was probably due to the fact that LPS stimulates macrophages to produce TNF. Conversely, when macrophages were pretreated with LPS for 18 h, washed, and assessed for lytic activity during the subsequent 18 h, lysis of LM cells was reduced relative to the endogenous level. Although macrophage lysis of P815 was not mediated by TNF, the addition of TNF to macrophage activation cultures facilitated LPS triggering of cytolytic activity against P815. Similarly, the addition of TNF to the activation cultures partially prevented the LPS-induced reduction in macrophage-mediated LM cell lysis. Taken together, these data suggest that TNF may act as an autocrine signal during macrophage activation, in addition to being directly lytic to a select number of sensitive target cell lines.     

The prognostic value of MDM2 overexpression in superficial urothelial bladder carcinoma

The prognostic significance of p53 accumulation and MDM2 overexpression in superficial and papillary urothelial cell carcinoma (UCC) of the bladder has not yet been established. Therefore, MDM2 and p53 protein were investigated focusing on tumour grade and muscularis mucosae invasion in order to identify their prognostic significance. Thirty-five archival UCC were studied by immunohistochemistry using monoclonal antibodies DO7 against p53, and IB10 against MDM2. MDM2 overexpression was observed in 51.4% of the cases. The recurrence rate for patients with MDM2 overexpression was 7.09 fold higher than for those without MDM2 overexpression. p53 accumulation was not related to prognosis. There was no significant difference between low and high grade tumours in regard to MDM2 overexpression and p53 accumulation. pTa cases presented the higher frequency of MDM2 positive cases (66.7%) and a lower frequency of p53 accumulation (33.3%). MDM2 overexpression does not seem to be related to muscular mucosae invasion. Thus, MDM2 status may well be a prognostic marker in superficial urothelial bladder carcinomas.     

SPARC enhances tumor stroma formation and prevents fibroblast activation

Tumor growth is influenced by interactions between malignant cells and the tumor stroma. Although the normal host microenvironment is nonpermissive for neoplastic progression, tumor-reactive stroma, characterized by the presence of activated fibroblasts, promotes neoplastic growth and metastasis. Secreted protein, acidic and rich in cysteine (SPARC) is a matricellular glycoprotein that is capable of inhibiting the growth of several different types of cancer. Recently, we reported that SPARC also impairs the growth of xenografts comprised of 293 cells. In this study, we show that in addition to enhancing stroma formation, SPARC prevents fibroblast activation in 293 xenografts, suggesting that the anti-cancer effects of SPARC may be due, at least in part, to the formation of tumor stroma that is not supportive of tumor growth. In vitro, 3T3 fibroblasts cocultured with SPARC-transfected 293 cells remain negative for alpha-smooth muscle actin, whereas wild-type 293 cells induce fibroblast activation. Moreover, activation of 3T3 cells and primary fibroblasts by transforming growth factor beta is blocked by SPARC treatment. We also demonstrate that SPARC significantly increases basic fibroblast growth factor-induced fibroblast migration in vitro, indicating that it may recruit host fibroblasts to the tumor stroma. Taken together, our results suggest that in addition to blocking angiogenesis, SPARC may inhibit tumor growth by promoting the assembly of stroma that is non-permissive for tumor progression.     

Role of tumor cell adhesion and migration in organ-specific metastasis formation

To form clinically evident metastases--the main cause of death in cancer patients--, tumor cells (TC) must complete a highly complex series of steps called the metastatic cascade, including local invasiveness, intravasation, circulation, adhesion and extravasation, survival, proliferation and angiogenesis. Since failure of any one of these steps results in metastatic failure, understanding the metastatic cascade may guide us to new therapeutic concepts. Here we review the role of specific TC adhesion and migration processes for organ-selective metastasis formation. TC adhesion in the microvasculature of host organs is a specific and highly regulated process mainly mediated by selectins for TC/endothelial cell binding and by integrins for TC/extracellular matrix interactions. Defined expression of the adhesion molecules and their corresponding ligands in the host organs and on the TC governs organ-selective non-random TC arrest. TC motility and subsequent chemotactically guided extravasation of adherent cells is the second rate-limiting step in organ-specific metastasis formation. Only if cells have completed adhesion and extravasation the growth of micrometastases and finally clinically evident metastases can occur.     

Cytokeratin expression patterns in low-grade papillary urothelial neoplasms of the urinary bladder

BACKGROUND: The differential expression patterns of cytokeratin 20 (CK20) and 34betaE12 antigen in low-grade papillary urothelial tumors of the bladder are discussed. METHODS: A retrospective study of 120 patients with low-grade papillary bladder tumors (45 neoplasms of low malignant potential and 75 low-grade WHO G1 carcinomas) was performed. All tumors were graded in accordance with the 1998 World Health Organization/International Society of Urological Pathology (WHO/ISUP) and 1999 WHO classifications. The mean follow-up was 76.6 months (range, 36-168 mos), considering for prognostic purposes the time to first recurrence, or relapse-free interval (RFI), and the total number of recurrent patients. Immunohistochemically, normal or abnormal CK20 and 34betaE12 antigen expression patterns were determined for each patient. CK20 (clone IT-Ks) and a high-molecular weight cytokeratin (clone 34betaE12) were the monoclonal antibodies used in the immunohistochemical study. RESULTS: Seventy-seven of 120 patients (64.2%) experienced a recurrence during follow-up. In recurrence prediction, the differential expression pattern of both cytokeratins showed a high sensitivity (76.6% for CK20 and 80.5% for 34betaE12 antigen) and a high positive predictive value (85.5% for CK20 and 75.6% for 34betaE12 antigen), although specificity was higher for CK20 (76.7%) than it was for 34betaE12 antigen (53.4%). Independent of adjuvant intravesical chemotherapy, these 2 markers showed a strong statistical correlation (p < 0.001) in univariate studies with both the prediction of disease recurrences and RFI. CONCLUSIONS: CK20 and 34betaE12 antigen have proved to be strong predictive markers of disease recurrences when considering different topographic expression profiles, and, in the authors' opinion, these profiles could be incorporated into follow-up clinicopathologic strategies.