Interleukin (IL)-6 is reported to function as a growth factor for renal and prostatic carcinomas. We conducted the present study to define the role of IL-6 in the growth of normal and neoplastic urothelial cells. Human bladder carcinoma cell lines (253J, RT4 and T24) and primary cultured human urothelial cells derived from normal ureters were used. Recombinant human IL-6 stimulated the growth of bladder carcinoma cell lines far better than that of normal urothelial cells (p F 0.001). All carcinoma cell lines tested produced and released IL-6, whereas normal urothelial cells did so only at marginal levels. Furthermore, treatment with lipopolysaccharide derived from Escherichia coli, tumor necrosis factor-a or IL-1 increased IL-6 secretion by bladder carcinoma cell lines but not by normal urothelial cells. Growth of bladder carcinoma cells was significantly inhibited by anti-IL-6 neutralizing antibody or the anti-sense oligonucleotide for IL-6 cDNA. We conclude that IL-6 functions as an autocrine growth factor for bladder carcinoma cells but not for normal urothelial cells and that it may be a factor accounting for the marked enhancement of inflammation-associated bladder carcinogenesis and tumor growth. Interleukin (IL)-6, originally identified as a T cell-derived cytokine that induces final maturation of B cells into antibodyproducing cells , exhibits multiple biologic activities that differ widely among various types of tissue and cell. IL-6 can enhance or inhibit the proliferation of carcinoma cells (Eustace et al., 1993;Miki et al., 1989;Tam et al., 1989). A variety of malignant tumors, including squamous-cell carcinomas and adenocarcinomas, have been shown to contain or synthesize IL-6, and autocrine growth stimulation has been suggested as the mechanism for IL-6 action (Eustace et al., 1993;Lu and Kerbel, 1993). In the genito-urinary system, IL-6 functions as an autocrine growth factor for renal-cell and prostatic carcinomas (Miki et al., 1989;Takenawa et al., 1991;Borsellino et al., 1995;Okamoto et al., 1997).We have shown that a continuous inflammatory stimulus strikingly accelerates N-methyl-N-nitrosourea-initiated rat urinary bladder carcinogenesis (Yamamoto et al., 1992;Kawai et al., 1993Kawai et al., , 1994 and that transformation in vitro can be enhanced significantly by IL-6 treatment (Okamoto et al., 1995). Furthermore, we observed that IL-6 released by inflammatory cells and bladder stromal cells could greatly stimulate the growth of non-tumorigenic and tumorigenic rat urothelial cell lines that did not secrete IL-6 and that transfected IL-6 markedly accelerated the growth rate of low-tumorigenicity rat urothelial cells ; data not shown). These findings suggest that IL-6 functions as a paracrine growth factor for bladder epithelial cells in vitro.Several reports, however, suggest that IL-6 is an autocrine growth factor in bladder cancer. Meyers et al. (1991) reported that specific mRNAs for both IL-6 and IL-6 receptor were expressed in de novo bladder carcinomas and bladder carcinoma cell lines. S...

The induction of phase 2 detoxifying enzymes, such as UDP-glucuronosyltransferases (UGTs), in response to an array of naturally occurring and synthetic agents, such as oltipraz (4-methyl-5-[2-pyrazinyl]-1,2-dithiole-3-thione), provides an effective means of protection against a variety of carcinogens. Transcription factor Nrf2 is an essential regulator of the inducible expression of detoxifying enzyme genes by chemopreventive agents. In this study, we investigated in Nrf2-deficient mice the susceptibility to the urinary bladder-specific carcinogen N-nitrosobutyl(4-hydroxybutyl)amine (BBN) and the chemopreventive efficacy of oltipraz. The incidence of urinary bladder carcinoma by BBN was significantly higher in Nrf2 ؊/؊ mice than in wild-type mice; invasive carcinoma was found in 24.0 and 38.5% of wild-type and Nrf2 ؊/؊ mice, respectively. Oltipraz induced the phase 2 enzymes responsible for BBN detoxification in the liver and urinary bladder in an Nrf2-dependent manner. As expected, therefore, oltipraz decreased the incidence of urinary bladder carcinoma by BBN in wild-type mice but had little effect in Nrf2 ؊/؊ mice. In wild-type mouse liver, oltipraz significantly induced BBN glucuronidation and decreased the urinary concentration of N-nitrosobutyl(3-carboxypropyl)amine, a proximate carcinogen of BBN. Importantly, BBN was found to suppress the expression of UGT1A specifically in the urinary bladder. This suppression was counteracted by oltipraz in wild-type mice but not in Nrf2 ؊/؊ mice. These results show that Nrf2 and its downstream target genes are responsible for BBN detoxification. Furthermore, oltipraz prevents carcinogenesis by BBN by enhancing detoxification of this carcinogen in the liver and urinary bladder.

A number of bladder tumors can arise from the uncontrolled spread of a single transformed cell. These tumors can then grow independently with variable subsequent genetic alterations.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily of ligand-activated transcription factors and is expressed in several types of tissue. Although PPARgamma reportedly is expressed in normal urothelium, its function is unknown. We examined the expression of PPARgamma in normal urothelium and bladder cancer in an attempt to assess its functional role. Immunohistochemical staining revealed normal urothelium to express PPARgamma uniformly. All low-grade carcinomas were positive either diffusely or focally, whereas staining was primarily focal or absent in high-grade carcinomas. A nonneoplastic urothelial cell line (1T-1), a low-grade (RT4) carcinoma cell line, and two high-grade (T24 and 253J) carcinoma cell lines in culture expressed PPARgamma mRNA and protein. Luciferase assay indicated that PPARgamma was functional. PPARgamma ligands (15-deoxy-Delta(12,14)-prostaglandin J(2), troglitazone and pioglitazone) suppressed the growth of nonneoplastic and neoplastic urothelial cells in a dose-dependent manner. However, neoplastic cells were more resistant than were nonneoplastic cells. Failure to express PPARgamma or ineffective transcriptional activity may be some of the mechanisms responsible for resistance to the inhibitory action of PPARgamma ligands.

Relative deficiency of transcription factors associated with methylation is responsible for the lack of AR promoter function in most of AR-negative cell lines. Mutations in the AR gene are present in the cells that express the AR but are androgen-independent.