New Treatments in Renal Cancer: The AhR Ligands.

Kidney cancer rapidly acquires resistance to antiangiogenic agents, such as sunitinib, developing an aggressive migratory phenotype (facilitated by c-Metsignal transduction). The Aryl hydrocarbon receptor (AhR) has recently been postulated as a molecular target for cancer treatment. Currently, there are two antitumor agent AhR ligands, with activity against renal cancer, that have been tested clinically: aminoflavone (AFP 464, NSC710464) and the benzothiazole (5F 203) prodrug Phortress. Our studies investigated the action of AFP 464, the aminoflavone pro-drug currently used in clinical trials, and 5F 203 on renal cancer cells, specifically examining their effects on cell cycle progression, apoptosis and cell migration. Both compounds caused cell cycle arrest and apoptosis but only 5F 203 potently inhibited the migration of TK-10, Caki-1 and SN12C cells as well as the migration signal transduction cascade, involving c-Met signaling, in TK-10 cells. Current investigations are focused on the development of nano-delivery vehicles, apoferritin-encapsulated benzothiazoles 5F 203 and GW610, for the treatment of renal cancer. These compounds have shown improved antitumor effects against TK-10 cells in vitro at lower concentrations compared with a naked agent.

Effect of nitric oxide inhibition in Bacillus Calmette-Guerin bladder cancer treatment.

BACKGROUND: Bacillus Calmette-Guerin (BCG) is the standard treatment for patients with high-risk non-muscle invasive bladder cancer (BC). Despite its success, about 30-50% of patients are refractory. It was reported that inducible nitric oxide synthase (iNOS) tumor expression is presented in 50% of human BC, associated with bad prognosis and BCG failure. OBJECTIVE: to evaluate in human bladder tumors the association between iNOS expression and the tumor microenvironment focusing on the immunosuppressive protein S100A9. Also, investigate in a preclinical murine MB49-BC model the tumor immunoresponse induced by BCG in combination with the nitric oxide production inhibitor l-NAME. RESULTS: In human bladder tumors, we detected a positive association between iNOS and S100A9 tumor expression, suggesting a relationship between both immunomodulatory proteins. We also found a positive correlation between iNOS tumor expression and the presence of S100A9+ tumor-infiltrating cells, suggesting an immunosuppressive tumor microenvironment induced by the nitric oxide production. Using the subcutaneous murine BC model, we show that similarly to the human pathology, MB49 tumors constitutively expressed iNOS and S100A9 protein. MB49 tumor-bearing mice presented an immunosuppressive systemic profile characterized by fewer cytotoxic cells (CD8+ and NK) and higher suppressor cells (Treg and myeloid-derived suppressor cells -MDSC-) compared to normal mice. BCG treatment reduced tumor growth, increasing local CD8+-infiltrating cells and induced a systemic increase in CD8+ and a reduction in Treg. BCG combined with l-NAME, significantly reduced tumor growth compared to BCG alone, diminishing iNOS and S100A9 tumor expression and increasing CD8+-infiltrating cells in tumor microenvironment. This local response was accompanied by the systemic increase in CD8+ and NK cells, and the reduction in Treg and MDSC, even more than BCG alone. Similar results were obtained using the orthotopic BC model, where an increase in specific cytotoxicity against MB49 tumor cells was detected. CONCLUSION: The present study provides preclinical information where NO inhibition in iNOS-expressing bladder tumors could contribute to improve BCG antitumor immune response. The association between iNOS and S100A9 in human BC supports the hypothesis that iNOS expression is a negative prognostic factor and a promising therapeutic target.

Role of peroxisome proliferator activated receptor-gamma in bacillus Calmette-Guérin bladder cancer therapy.

PURPOSE: We evaluated the effects of combined PPARg agonist with bacillus Calmette-Guérin in bladder cancer growth in vitro and in vivo, focusing on the tissue remodeling mechanisms induced by bacillus Calmette-Guérin. MATERIALS AND METHODS: PPARs are a superfamily of nuclear receptors that are transcription factors activated by ligands. Activation of PPARg, the γ subtype, causes proliferation inhibition or differentiation of tumor cells. Previously, we reported that the inhibition of murine bladder tumor growth induced by bacillus Calmette-Guérin, which is the standard treatment for patients with nonmuscle invasive, high grade bladder cancer, increased PPARg expression in vitro and in vivo. In vitro the cell growth inhibition induced by bacillus Calmette-Guérin was enhanced by the PPARg agonist 15-d-PGJ2, raising the possibility that PPARg activation may be a therapeutic modality for this disease. RESULTS: In MB49 cells bacillus Calmette-Guérin and 15-d-PGJ2 induced PPARg expression, nuclear translocation and transcriptional activity. In vivo bacillus Calmette-Guérin reduced tumor size, an effect that was partially reversed when bacillus Calmette-Guérin was combined with the PPARg agonist rosiglitazone. The same result was found when we analyzed the effect of the PPARg antagonist BADGE (Fluka Chemical, Buchs, Switzerland) combined with bacillus Calmette-Guérin. Analysis of the activation of macrophages and fibroblasts demonstrated that rosiglitazone inhibited the tissue remodeling mechanisms induced by bacillus Calmette-Guérin. CONCLUSIONS: Results suggest that PPARg is involved in the antitumor action of bacillus Calmette-Guérin. However, exogenous PPARg agonists would not be a favorable therapeutic modality because they can inhibit the tissue remodeling needed for an overall satisfactory bacillus Calmette-Guérin response.

Inducible nitric oxide synthase and PPARγ are involved in bladder cancer progression.

PURPOSE: We evaluated the role of inducible nitric oxide synthase and PPARγ as prognostic factors for bladder cancer. MATERIALS AND METHODS: Inducible nitric oxide synthase and PPARγ were evaluated by Western blot and immunohistochemistry in a mouse bladder cancer model of nonmuscle invasive and invasive MB49-I tumor cells, and in human bladder cancer samples. RESULTS: Inducible nitric oxide synthase expression was negative in mouse normal urothelium and higher in invasive than in noninvasive MB49 tumors. In vitro inducible nitric oxide synthase activity, determined as nitrite, was higher in MB49-I than in MB49 cells (p <0.001). In human samples expression was also associated with tumor invasion. Nuclear PPARγ expression was negative in normal mouse urothelium but higher in nonmuscle invasive MB49 than in MB49-I tumors. Similarly in human tumors low PPARγ was associated with poor prognosis factors, such as high histological grade (p = 0.0160) and invasion status (p = 0.0352). A positive correlation was noted between inducible nitric oxide synthase and PPARγ in low histological grade and nonmuscle invasive tumors (Pearson correlation index 0.6368, p = 0.0351, 0.4438 and 0.0168, respectively). As determined by gene reporter assay, PPARγ activity was induced by nitric oxide only in nonmuscle invasive MB49 cells (p <0.001). CONCLUSIONS: Results suggest that increased PPARγ controls inducible nitric oxide synthase expression at early tumor stages. However, regulation is lost at advanced tumor stages, when the increase in inducible nitric oxide synthase and the decrease in PPARγ seem to be associated with bladder cancer progression.

Determinación de óxido nítrico urinario como posible marcador de carcinomas y melanomas

Objetivos: Determinación del nivel urinario de NO, como indicador de presencia de carcinomas y melanomas en pacientes oncológicos. Estudio de la asociación con el estadío tumoral. Análisis de especificidad y sensibilidad del ensayo evaluando controles sanos y pacientes con otros tumores no relacionados. Determinar los niveles de NO en orina (determinados como contenido de nitrito) en controles sanos; pacientes con carcinoma de cavidad oral, laringe y. esófago; pacientes con melanomas en diferentes localizaciones; pacientes con tumores de piel no melanomas. Establecer la especificidad y sensibilidad del ensayo para diferenciar pacientes con carcinoma y/o melanoma de controles sanos y otros tumores. I

Nitric oxide in patients with transitional bladder cancer.

BACKGROUND AND OBJECTIVES: One of the current challenges in clinical oncology is the identification of patients with superficial transitional bladder carcinoma (TBC) at high risk of recurrence or myoinvasive disease. Recently, inducible nitric oxide synthase (iNOS) expression was detected in urinary bladder cancers. Because iNOS produces a high concentration of nitric oxide (NO), we thought it possible that urine from TBC patients produces high levels of NO. The aim of this study was to determine urine NO levels in TBC compared with healthy controls and with patients bearing other nonrelated tumors, as well as to examine iNOS expression in bladder cancer tissue. METHODS: This study evaluated patients with TBC (n = 33), with gynecological tumors (GT) (n = 19), TBC patients with no evidence of tumor (no evidence of disease [NED]) (n = 19), and healthy subjects (n = 39). Urine NO levels were determined by Griess reagent, expressed as microM NO(2) (-)/100 mg creatinine. RESULTS: TBC patients produced significantly higher urine NO median values (4.2 microM; range, 2.1-91.6) than were produced by healthy individuals (2.1 microM; range, 0.4-4.9), by the NED group (1.7 microM; range 1.2-5.4), and by GT patients (2.0 microM; range, 0.8-58.1) (P = 0.000, Kruskal-Wallis test). iNOS was detected by Western blot in 52% (13/25) of bladder tumors examined. CONCLUSIONS: Although a wider study is necessary, our results suggest that the enhanced NO levels could perhaps be considered as a putative marker in TBC patients.

Determinación de óxido nítrico urinario como posible marcador de carcinomas y melanomas

Objetivos: Determinación del nivel urinario de NO, como indicador de presencia de carcinomas y melanomas en pacientes oncológicos. Estudio de la asociación con el estadío tumoral. Análisis de especificidad y sensibilidad del ensayo evaluando controles sanos y pacientes con otros tumores no relacionados. Determinar los niveles de NO en orina (determinados como contenido de nitrito) en controles sanos; pacientes con carcinoma de cavidad oral, laringe y. esófago; pacientes con melanomas en diferentes localizaciones; pacientes con tumores de piel no melanomas. Establecer la especificidad y sensibilidad del ensayo para diferenciar pacientes con carcinoma y/o melanoma de controles sanos y otros tumores. I

Determinación de óxido nítrico urinario como posible marcador de carcinomas y melanomas

Objetivos: Determinación del nivel urinario de NO, como indicador de presencia de carcinomas y melanomas en pacientes oncológicos. Estudio de la asociación con el estadío tumoral. Análisis de especificidad y sensibilidad del ensayo evaluando controles sanos y pacientes con otros tumores no relacionados. Determinar los niveles de NO en orina (determinados como contenido de nitrito) en controles sanos; pacientes con carcinoma de cavidad oral, laringe y. esófago; pacientes con melanomas en diferentes localizaciones; pacientes con tumores de piel no melanomas. Establecer la especificidad y sensibilidad del ensayo para diferenciar pacientes con carcinoma y/o melanoma de controles sanos y otros tumores. I