Gemcitabine-induced Gli-dependent activation of hedgehog pathway resists to the treatment of urothelial carcinoma cells

Patients with urothelial carcinoma (UC) experience gemcitabine resistance is a critical issue. The role of hedgehog pathway in the problem was explored. The expressions of phospho-AKT.sup.ser473, phospho-GSK3[beta].sup.ser9 and Gli2 were up-regulated in gemcitabine-resistant NTUB1 (NGR) cells. Without hedgehog ligands, Gli proteins can be phosphorylated by GSK3[beta] kinase to inhibit their downstream regulations. Furthermore, the GSK3[beta] kinase can be phosphorylated by AKT at its Ser9 residue to become an inactive kinase. Therefore, overexpression of AKT1, Flag-GSK.sup.S9D (constitutively inactive form) or active Gli2 (GLI2[DELTA]N) in NTUB1 cells could activate Gli2 pathway to enhance migration/invasion ability and increase gemcitabine resistance, respectively. Conversely, overexpression of Flag-GSK.sup.S9A (constitutively active form) or knockdown of Gli2 could suppress Gli2 pathway, and then reduce gemcitabine resistance in NGR cells. Therefore, we suggest gemcitabine-activated AKT/GSK3[beta] pathway can elicit Gli2 activity, which leads to enhanced migration/invasion ability and resistance to gemcitabine therapy in UC patients. The non-canonical hedgehog pathway should be evaluated in the therapy to benefit UC patients.