Tumor and microenvironment modification during progression of murine orthotopic bladder cancer.

The aim of this study was to monitor changes in the expression of immune-related genes in the bladder after tumor implantation. Mice were orthotopically implanted with MB49-PSA cells (C57BL/6 mice) on day 1 and terminated on days 7, 14, 21, and 28. Another mouse model (MBT-2/C3H mice) was examined at day 7. Gene expression analysis was performed using a TaqMan Low Density Mouse Immune Panel (Applied Biosystems, USA) on RNA extracted from the bladders. Selected genes were reconfirmed by real-time PCR analysis and RT-PCR on the mRNA from other animals. Immune suppressive (IL13, IL1ß, PTGS2, NOS2, IL10, CTLA4, and CCL22) and immune stimulatory genes (CSF2, GZMB, IFNγ, CXCL10, TNFα, CD80, IL12a, and IL6) and AGTR2 were increased by day 7. By day 28, IL10, CCL2, CCL5, CXCL11, CTLA4, GZMB, IFNγ, CSF2, and IL6 were significantly increased. Therapeutic strategies involving TH1 induction and TH2 dampening may improve responses to immunotherapy.

Internalization of Mycobacterium bovis, Bacillus Calmette Guerin, by bladder cancer cells is cytotoxic.

Instillation of Bacillus Calmette Guerin (BCG) into the bladder is the standard treatment for superficial bladder cancer. It leads to a local inflammatory response due to the release of cytokines and influx of immune cells to the tumor site. Although the presence of an intact immune system is an essential criterion for successful therapy, attachment of the bacteria to the bladder urothelial is just as important. The purpose of our study is to determine the role of bacterial internalization by epithelial cells. Transfection of the alpha5 integrin gene into the BCG unresponsive bladder cancer cell line, RT4, caused an increase in bacterial uptake and also increased cell death. Treatment of cells with cycloheximide did not prevent bacterial internalization but blocked its cytotoxic effect suggesting that unlike cell death, the process of bacterial internalization does not require new protein synthesis. Our data also show that the bacteria secretory products can prevent its own internalization. The extract prepared from lyophilized BCG altered the phosphorylation status of the focal adhesion kinase which is responsible for cellular endocytosis. Therefore, bacterial phosphatases may be present in the bacterial extract. Their activity may inhibit BCG internalization. Thus washing the reconstituted bacteria to remove the enzymes before instillation into the bladder might improve the therapeutic outcome of intravesical BCG therapy.

Combination of thiol antioxidant Silibinin with Brostallicin is associated with increase in the anti-apoptotic protein Bcl-2 and decrease in caspase 3 activity.

The cytotoxic activity of Brostallicin was previously shown to be enhanced in the presence of high glutathione and glutathione transferase levels. We hypothesized that thiol antioxidants, N-acetylcysteine and Silibinin, could potentiate Brostallicin's cytotoxicity in a similar way. HepG2 and CNE-2 cells were treated with N-acetylcysteine, Silibinin and Brostallicin, either alone or in combination. Surprisingly, we found that NAC and Silibinin had adverse effects on Brostallicin's cytotoxicity. The mechanism underlying the interaction involved the apoptotic pathway as we demonstrated an increase in Bcl-2 protein levels and decrease in caspase 3 activity with the Silibinin-Brostallicin combination.

N-acetylcysteine augments the cellular redox changes and cytotoxic activity of internalized mycobacterium bovis in human bladder cancer cells.

PURPOSE: We determined whether changes in cellular reactive oxygen species correlated with mycobacteria internalization and bladder cancer cell death. MATERIALS AND METHODS: Reactive oxygen species and thiols in RT112 and MGH bladder cancer cells were determined using the fluorescence probes 5-(and 6)-carboxy-2', 7' dichlorodihydrofluorescein diacetate and monobromobimane. Superoxide and nitrite production were measured using bis-N-methylarcridinium nitrate and Griess reagents. Cytotoxicity was determined by the release of 14C-thymidine from cells with 14C labeled DNA. RESULTS: MGH cells that internalize bacillus Calmette-Guerin (BCG) had decreased cellular reactive oxygen species and thiols, although superoxide and nitric oxide production increased. RT112 cells, which do not internalize BCG, did not show a decrease in reactive oxygen species after incubation with BCG. Blocking BCG uptake in MGH cells abrogated reactive oxygen species reduction, confirming that the changes in reactive oxygen species were internalization dependent events. Treating cells with BCG and the antioxidant N-acetylcysteine caused a greater reduction in reactive oxygen species, and induced earlier and greater cytotoxicity in MGH but not in RT112 cells. CONCLUSIONS: The induction of bladder cancer cell killing by BCG parallels the ability of cells to internalize BCG, which in turn indicates that the susceptibility of tumor cells to the cytotoxic effects of BCG may be related to changes in cellular levels of reactive oxygen species and thiols. Supplementation with an antioxidant could enhance the antitumor effect of BCG.