ANTISENSE OLIGONUCLEOTIDE SPECIFIC FOR TRANSFORMING GROWTH-FACTOR-BETA-1 INHIBIT BOTH IN-VITRO AND IN-VIVO GROWTH OF MBT-2 MURINE BLADDER-CANCER

Introduction and Objectives: TGF-beta is a potent immunosuppressive cy tokine produced by many tumor cells. Secretion of TGF-beta by malignan t cells may be a mechanism by which tumor cells escape destruction by tumor-specific T lymphocytes. In this study, we used a TGF-beta produc ing C3H/He-MBT-2 murine bladder tumor model to investigate the feasibi lity of antisense oligonucleotide (ODN) gene therapy strategy to block the production of TGF-beta from tumor cells and evaluate its influenc e on both in vitro tumor growth and in vivo tumor formation. Materials and Methods: Using a plasmid, pRUFCD, we constructed a recombinant pl asmid pRUFCD/TGF-beta 1(-) containing-antisense TGF-beta ODN and then transfected it into MBT-2 cells by electroporation. Three transfectant clones were successfully obtained by their resistance to 5-fluorourac il and cytosine. Results: The secretion of TGF-beta from the three obt ained TGF-beta antisense-blocked MBT-2 cell clones, as assessed by ELI SA, were all decreased. Moreover, they all exhibited smaller colony si ze in the in vitro anchorage-independent soft agar colony forming assa y. Tumor growths in mice injected with these three clones were all inh ibited compared with those injected with pm ental tumor cells. Conclus ion: This study demonstrates that after reducing the secretion of TGF- beta 1 on tumor cells by TGF-beta 1 antisense, ODN can inhibit their i n vitro growth and in vivo tumor formation suggesting that this approa ch can be a potentially useful strategy to abolish the adverse immunos uppression effect of TGF-beta 1 producing autologous tumor vaccine and therefore to enhance host antitumor immune response.