Is interferon gamma one key of metastatic potential increase in human bladder carcinoma?

PURPOSE: IFN-gamma is detected in the urine of bladder cancer patients after intravesical bacillus Calmette Guerin instillation. Because it acts in the anticancer process, we studied its cellular and molecular mechanisms of action on human bladder cancer cell lines. RESULTS: IFN-gamma (>5 ng.ml(-1))(>400 IU.ml(-1)) inhibited the growth of bladder cancer cell lines and modified the expression of the tumor-associated markers tissue-type plasminogen activators, Plasminogen activator inhibitor-2, urokinase plasminogen activator receptor, colony-stimulating factor 1, intercellular adhesion molecule 1, and class II MHC. Interestingly, IFN-gamma-induced apoptosis of the low-grade bladder cancer cell lines (RT4/G1 and RT112/G2) related to a cleavage of caspases 1, 8, and 9. This process was inhibited by the phosphatidylinositol 3'-kinase inhibitor (LY294002) and the protein synthesis inhibitor (cycloheximide). Moreover, low doses of IFN-gamma (<5 ng.ml(-1))(<400 IU.ml(-1)) increased the resistance to the cytotoxic effect of tumor necrosis factor alpha in the RT112 cells but not in the RT4 cells. This acquired resistance was associated with morphological changes and with an increase of the cell migration and scattering. CONCLUSIONS: We demonstrated that in the low-grade bladder cancer cell lines, the effect of IFN-gamma was dose dependent: high doses (>5 ng.ml(-1)) induced apoptosis of RT4 and RT112 cells, whereas low doses (<5 ng.ml(-1)) induced a resistance to the cytotoxic effect of tumor necrosis factor alpha and increase the metastatic potential of the RT112 cells. Therefore, we propose that a similar phenomenon could participate to the immunotherapy failure observed during tumor progression of bladder cancer.

Plasminogen- and colony-stimulating factor-1-associated markers in bladder carcinoma: diagnostic value of urokinase plasminogen activator receptor and plasminogen activator inhibitor type-2 using immunocytochemical analysis.

The expression of plasminogen- and colony-stimulating factor-1-associated markers was first investigated in seven bladder carcinoma cell lines and in 15 primary bladder tumors using RT-PCR (mRNAs), zymography (protein activity), ELISA and immunocytochemistry analysis (ICC) (protein levels). The mRNAs expression, the activity and the levels of the secreted proteins were not informative. Only urokinase plasminogen activator receptor (uPA-R/CD87) and possibly plasminogen activator inhibitor type-2 (PAI2) antigen expression at the cellular levels seem to be useful markers. uPA-R antigen expression correlated with the secretion of hepatocyte growth factor (HGF) ( P=0.016) and the motility of the bladder tumor cells ( P=0.014), two markers associated with a poor prognosis in bladder carcinoma. To validate our technique and confirm these preliminary results, uPA-R and PAI2 antigen expression was determined in the imprints from 129 resected bladder carcinoma fragments. uPA-R correlated with the grade ( P=0.002), tumor invasion ( P=0.003) and the ploidy ( P=0.05) of the bladder carcinomas and with the low overall survival ( P=0.045) of the patients. PAI2 correlated only with the stage ( P=0.02) and low overall survival ( P=0.038). We conclude that in bladder carcinomas, studying the transcripts of PAs, PAIs, CSF-1 and its receptor, as well as measuring their concentration or activity in culture supernatants was of no clinical interest in terms of diagnostic or prognostic value. Only the ICC of uPA-R, which correlated with the major histopathological parameters of tumors and the low overall survival, proved to be a diagnostic and prognostic marker.