CONTEXT: The epidermal growth factor receptor (EGFR) family is reportedly overexpressed in bladder cancer, and tyrosine kinaseinhibitors (TKIs) have been suggested as treatment. Gefitinib is a selective inhibitor of the EGFR and lapatinib is a dual inhibitor of both the EGFR and HER2 (human EGFR type 2 receptor). Both compounds compete with the binding of adenosine triphosphate (ATP) to the tyrosine kinase domain of the respective receptors to inhibit receptor autophosphorylation causing suppression of signal transduction. Unfortunately, resistance to these inhibitors is a major clinical problem. AIMS: To compare the apoptosis signaling pathway(s) induced by gefitinib and lapatinib, in UM-UC-5 (drug-sensitive) and UM-UC-14 (drug-resistant) bladder cancer cells and to identify molecular differences that might be useful predictors of their efficacy. MATERIALS AND METHODS: Cell proliferation, cell cycle and apoptosis assay were used to detect the effect of TKIs on UM-UC-5 and UM-UC-14 cells. Molecular differences for response to TKIs were examined by protein array. RESULTS: TKIs strongly inhibited cell proliferation and induced cell cycle G1 arrest and apoptosis in UM-UC-5 cells. Most notable apoptosis molecular differences included decreased claspin, trail, and survivin by TKIs in the sensitive cells. In contrast, TKIs had no effect on resistant cells. CONCLUSIONS: Claspin, trail, and survivin might be used to determine the sensitivity of bladder cancers to TKIs.
CONTEXT: The epidermal growth factor receptor (EGFR) family is reportedly overexpressed in bladder cancer, and tyrosine kinaseinhibitors (TKIs) have been suggested as treatment. Gefitinib is a selective inhibitor of the EGFR and lapatinib is a dual inhibitor of both the EGFR and HER2 (humanEGFR type 2 receptor). Both compounds compete with the binding of adenosine triphosphate (ATP) to the tyrosine kinase domain of the respective receptors to inhibit receptor autophosphorylation causing suppression of signal transduction. Unfortunately, resistance to these inhibitors is a major clinical problem. AIMS: To compare the apoptosis signaling pathway(s) induced by gefitinib and lapatinib, in UM-UC-5 (drug-sensitive) and UM-UC-14 (drug-resistant) bladder cancer cells and to identify molecular differences that might be useful predictors of their efficacy. MATERIALS AND METHODS: Cell proliferation, cell cycle and apoptosis assay were used to detect the effect of TKIs on UM-UC-5 and UM-UC-14 cells. Molecular differences for response to TKIs were examined by protein array. RESULTS: TKIs strongly inhibited cell proliferation and induced cell cycle G1 arrest and apoptosis in UM-UC-5 cells. Most notable apoptosis molecular differences included decreased claspin, trail, and survivin by TKIs in the sensitive cells. In contrast, TKIs had no effect on resistant cells. CONCLUSIONS:Claspin, trail, and survivin might be used to determine the sensitivity of bladder cancers to TKIs.