The effect of intravesical Bacillus Calmette–Guerin instillations on the expression of inducible nitric oxide synthase in humans

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.

Outcome after BCG treatment for urinary bladder cancer may be influenced by polymorphisms in the NOS2 and NOS3 genes

Purpose

Bacillus Calmette-Guérin (BCG)-treatment is an established treatment for bladder cancer, but its mechanisms of action are not fully understood. High-risk non-muscle invasive bladder-cancer (NMIBC)-patients failing to respond to BCG-treatment have worse prognosis than those undergoing immediate radical cystectomy and identification of patients at risk for BCG-failure is of high priority. Several studies indicate a role for nitric oxide (NO) in the cytotoxic effect that BCG exerts on bladder cancer cells. In this study we investigated whether NO-synthase (NOS)-gene polymorphisms, NOS2-promoter microsatellite (CCTTT)n, and the NOS3-polymorphisms-786T>C (rs2070744) and Glu298Asp (rs1799983), can serve as possible molecular markers for outcome after BCG-treatment for NMIBC.

Materials and methods

All NMIBC-patients from a well-characterized population based cohort were analyzed (n=88). Polymorphism data were combined with information from 15-years of clinical follow-up. The effect of BCG-treatment on cancer-specific death (CSD), recurrence and progression in patients with varying NOS-genotypes were studied using Cox proportional hazard-models and log rank tests.

Results

BCG-treatment resulted in significantly better survival in patients without (Log rank: p=0.006; HR: 0.12, p=0.048), but not in patients with a long version ((CCTTT)n ≧13 repeats) of the NOS2-promoter microsatellite. The NOS3-rs2070744(TT) and rs1799983(GG)-genotypes showed decreased risk for CSD (Log rank(TT): p=0.001; Log rank(GG): p=0.010, HR(GG): 0.16, p=0.030) and progression (Log rank(TT): p<0.001, HR(TT): 0.05, p=0.005; Log rank(GG): p<0.001, HR(GG): 0.10, p=0.003) after BCG-therapy compared to the other genotypes. There was also a reduction in recurrence in BCG-treated patients that was mostly genotype independent. Analysis of combined genotypes identified a subgroup of 30% of the BCG-treated patients that did not benefit from BCG-treatment.

Conclusions

Our results suggest that the investigated polymorphisms influence patient response to BCG-treatment and thus may serve as possible markers for identification of BCG-failures.

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30% of BCG treated bladder cancer (NMIBC)-patients do not respond to BCG-treatment.

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We need to identify BCG failures before the BCG-treatment is given.

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Altered NOS2 and NOS3 gene activity may be associated with BCG treatment outcome.

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NOS-polymorphisms are possible BCG-failure biomarkers in bladder cancer patients.

H2O2 generation by bacillus Calmette-Guérin induces the cellular oxidative stress response required for bacillus Calmette-Guérin direct effects on urothelial carcinoma biology

PURPOSE

Exposure of urothelial carcinoma cells to bacillus Calmette-Guérin affects cellular redox status and tumor cell biology but the mechanism(s) remain unclear. We examined free radical production by bacillus Calmette-Guérin in tumor cells in response to the bacillus using global profiling of reactive oxygen species/reactive nitrogen species. The relationship between free radical generation and downstream cellular events was evaluated.

MATERIALS AND METHODS

Using fluorescent probes we performed global profiling of reactive oxygen species/reactive nitrogen species in heat killed and viable bacillus Calmette-Guérin, and in the 253J and T24 urothelial carcinoma cell lines after exposure to the bacillus. Inhibition of bacillus Calmette-Guérin internalization and H2O2 pharmacological scavenging were studied for their effect on cellular reactive oxygen species/reactive nitrogen species generation and various physiological end points.

RESULTS

Viable bacillus Calmette-Guérin produced H2O2 and O2(-) but nitric oxide was not generated. Loss of viability decreased H2O2 production by 50% compared to viable bacillus. Bacillus Calmette-Guérin internalization was necessary for the bacillus to induce reactive oxygen species/reactive nitrogen species generation in urothelial carcinoma cells. Pharmacological H2O2 scavenging reversed reactive oxygen species/reactive nitrogen species mediated signaling in urothelial carcinoma cells. Bacillus Calmette-Guérin dependent alterations in tumor biology, including intracellular signaling, gene expression and cytotoxicity, depended on free radical generation.

CONCLUSIONS

This study demonstrates the importance of free radical generation by bacillus Calmette-Guérin and intracellular generation of cellular oxidative stress on the urothelial carcinoma cell response to the bacillus. Manipulating the cellular oxidative stress induced by bacillus Calmette-Guérin represents a potential target to increase the efficacy of the bacillus.

Secondary stimulation from Bacillus Calmette-Guérin induced macrophages induce nitric oxide independent cell-death in bladder cancer cells

The anti-tumour mechanisms following Bacillus Calmette-Guérin (BCG) treatment of bladder-cancer remain largely unknown. Previous studies have shown involvement of nitric-oxide (NO) formation in the BCG-mediated effect. We analyzed the effects of macrophage secreted factors (MSFs) from BCG-stimulated RAW264.7 cells on the bladder-cancer cell line MBT2. Direct treatment with BCG did not induce NO in MBT2-cells whereas supernatant from BCG-stimulated macrophages increased NOS2 mRNA and protein expression, NO concentrations and cell-death. Blocking NO-synthesis with the NOS-inhibitor L-NAME did not affect levels of cell-death suggesting cytotoxic pathways involving other signalling molecules than NO. Several such candidate genes were identified in a microarray.

iNOS expression and NO production contribute to the direct effects of BCG on urothelial carcinoma cell biology

OBJECTIVES

Evidence suggests that oxidative stress occurring as a consequence of inducible nitric oxide synthase/nitric oxide (iNOS/NO) contributes to the biologic effects of bacille Calmette-Guérin (BCG). Objective of this study is to examine iNOS expression, NO production, and the biologic effect of NO on established intermediate end points for the human urothelial carcinoma cell response to BCG.

MATERIALS AND METHODS

Quantitative reverse transcriptase-polymerase chain reaction and real-time measurement of NO was used to assess iNOS and NO production, respectively, in 2 human urothelial carcinoma (UC) cell lines, in response to BCG. The effect of blocking NO production using the specific iNOS inhibitor 1400W was determined for multiple intermediate end points characterizing BCG's direct effects on tumor cell biology. Activation of nuclear factor kappa B and nuclear factor (erythroid-derived 2)-like 2 signaling pathways, transactivation of genes, including p21, CD54, IL6, IL8, CXCL1, CXCL3, CCL20, and cytotoxicity, as measured by vital dye exclusion, lactate dehydrogenase release, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay were measured in response to BCG with and without iNOS inhibition.

RESULTS

Exposure of UC cells to BCG significantly increased both iNOS expression and NO production. Inhibition of iNOS activity with 1400W significantly inhibited BCG's direct biologic effect on UC cells for all of the end points evaluated.

CONCLUSIONS

iNOS expression, NO production, and the associated oxidative stress play a central role in the response of UC cells to BCG exposure. Manipulation of oxidative stress may afford an opportunity to enhance the antitumor effects of BCG.

Bacillus Calmette Guerin induces fibroblast activation both directly and through macrophages in a mouse bladder cancer model

BACKGROUND

Bacillus Calmette-Guerin (BCG) is the most effective treatment for non-muscle invasive bladder cancer. However, a failure in the initial response or relapse within the first five years of treatment has been observed in 20% of patients. We have previously observed that in vivo administration of an inhibitor of nitric oxide improved the response to BCG of bladder tumor bearing mice. It was described that this effect was due to a replacement of tumor tissue by collagen depots. The aim of the present work was to clarify the mechanism involved in this process.

METHODOLOGY/PRINCIPAL FINDINGS

We demonstrated that BCG induces NIH-3T3 fibroblast proliferation by activating the MAPK and PI3K signaling pathways and also differentiation determined by alpha-smooth muscle actin (alpha-SMA) expression. In vivo, intratumoral inoculation of BCG also increased alpha-SMA and collagen expression. Oral administration of L-NAME enhanced the pro-fibrotic effect of BCG. Peritoneal macrophages obtained from MB49 tumor-bearing mice treated in vivo with combined treatment of BCG with L-NAME also enhanced fibroblast proliferation. We observed that FGF-2 is one of the factors released by BCG-activated macrophages that is able to induce fibroblast proliferation. The involvement of FGF-2 was evidenced using an anti-FGF2 antibody. At the same time, this macrophage population improved wound healing rate in normal mice and FGF-2 expression was also increased in these wounds.

CONCLUSIONS/SIGNIFICANCE

Our findings suggest that fibroblasts are targeted by BCG both directly and through activated macrophages in an immunotherapy context of a bladder murine model. We also described, for the first time, that FGF-2 is involved in a dialog between fibroblasts and macrophages induced after BCG treatment. The fact that L-NAME administration improves the BCG effect on fibroblasts, NO inhibition, might represent a new approach to add to the conventional BCG therapy.

Can the levels of nitric oxide in the urine, serum and tumor tissue be putative markers for bladder cancer?

AIM

To determine nitric oxide (NO) levels in serum, urine, tumor tissue and non-malignant adjacent tissue in bladder cancer patients compared with those in patients with a non-neoplastic genitourinary disease and to evaluate postoperative serum and urine NO change.

METHODS

Samples was collected in 20 cancer and 41 control patients. Griess reagent was used for NO measurements.

RESULTS

Mean age in the cancer and control groups was 64.2 +/- 9.9 and 63.7 +/- 8.9 years, respectively. Preoperatively, urinary infection incidence was not statistically different between groups. There were no significant differences in serum, urine and tissue NO levels in patients with and without infection in both groups. Hematuria was found to not affect urine NO level in the cancer group. Urine NO level was significantly higher than in controls preoperatively, decreased significantly following operation and remained stable after the third month. High serum NO values decreased at the early postoperative period; however, they re-increased in the long-term. No significant differences were observed in the third month in serum and urine NO levels between the patients with (no. 6) and without (no. 14) residual or relapsing tumor. No statistical difference was observed between NO levels in non-malignant adjacent and control tissues. However, tumor tissue NO level was significantly higher than those in the other two. There were no statistical differences in the first and third month serum and urine NO levels between patients who underwent bacillus Calmette-Guérin instillation therapy postoperatively and the patients who took chemotherapy or no further treatment.

CONCLUSIONS

Both local and generalized host defense mechanisms seem to function in bladder cancer patients. Although further evaluation with a longer observation period and larger numbers of patients is necessary, results suggest that serum and urine NO levels are not putative and useful markers for bladder cancer.

Enhanced formation of nitric oxide in bladder carcinoma in situ and in BCG treated bladder cancer

The purpose of the study was to analyze endogenous nitric oxide (NO) formation and NO-synthase (NOS) gene expression in the urinary bladder from patients with urinary bladder cancer and to investigate the relationship between local NO formation, treatment with Bacillus Calmette Guerin (BCG) and clinical stage in bladder cancer patients. One hundred and three patients with bladder cancer were studied. Endogenous formation of NO was measured in 72 patients, including 6 patients with BCG treated bladder cancer and 6 tumor free control subjects. iNOS expression was analyzed at transcriptional and protein level in biopsies from 31 patients with bladder cancer by real time polymerase chain reaction (PCR) and Western blot (WB), respectively. Three patients in this group had received BCG treatment. Eight biopsies from normal bladder served as control for PCR and WB analysis. Patients with carcinoma in situ (CIS) had higher iNOS expression (p<0.01) and NO formation (p<0.01) than control subjects and patients with papillary tumors without concomitant CIS. Markedly increased iNOS expression (p<0.05) and NO formation (p<0.001) were also found in patients treated with BCG as compared to the other groups. In conclusion, the presence of elevated NO concentration and iNOS expression in the urinary bladder from BCG treated patients and patients with CIS further supports the notion that NO may be an important factor in bladder cancer biology and that the BCG effect on superficial bladder cancer may partly be due to stimulation of local NO formation.