[Immunostimulatory CpG oligodeoxynucleotides (CpG-ODN) in an orthotopic murine transitional cell carcinoma (TCC) model. Effect on local cytokine expression].

CpG-oligodeoxynucleotides (CpG-ODN) are potent stimulators of the innate immune system. They promote a Th1-biased immune response with antineoplastic potential. We recently demonstrated antitumoral effects of CpG-ODN in murine transitional cell carcinoma (TCC) models. The purpose of the present work was to more precisely define the immunological nature of this immunotherapeutic approach to TCC.MB-49 TCC was established in female C57/Bl6 mice by intravesical tumor cell instillation after poly-L-lysine conditioning of the bladder (day 0) as described previously. Three groups of six mice were treated: intravesical instillation of 50 microl PBS on days 1, 3, 5, and 7 (group 1, untreated control); 10 nmol CpG 1668 on days 1, 3, 5, and 7 (group 2); and 10 nmol GpC 1668 on days 1, 3, 5, and 7 (group 3). Six native bladders served as no-treatment/no-tumor controls (group 4). Mice were sacrificed on day 11; bladders and draining lymph nodes were removed, and mRNA was prepared for quantitative real-time polymerase chain reaction. Samples were analyzed on a Bio-Rad iCycler for IL 10, TGF-beta, IL 12, and IFNgamma expression; threshold values were compared to beta-actin as housekeeping gene.Tumor take was 100%. Three animals in group 1 had to be sacrificed in advance due to rapid tumor progression. Relative cytokine expression was comparable in groups 1 and 4. IL-10, IL-12, TGF-beta, and IFNgamma were overexpressed in groups 2 and 3. CpG-ODN treatment of murine TCC results in overexpression of both classic Th1 cytokines (IL 12 and IFNgamma) and the Th2 marker IL 10. TGF-beta expression is increased as well. These phenomena are not induced by the growing TCC but by CpG-ODN therapy. They are accompanied by an objective clinical response, as we were able to show recently. Immunostimulatory DNA holds promise to be a novel therapeutic agent in TCC.