MP61-20 PRIMARY APPLICATION STUDY IN EARLY DIAGNOSIS OF BLADDER CANCER BY CELL-PERMEABLE PEPTIDES R11

INTRODUCTION AND OBJECTIVES: Despite the potential therapeutic efficacy of EGFR inhibitors in advanced stage bladder cancer, there are no currently clear evidences yet. Here, we investigate whether combined treatment of EGFR inhibitors and inhibition of autophagy activities exerts the synergistic anti-cancer effects in human bladder cancer cells. METHODS: We used T24 and J82 bladder cancer cells with treatment of Gefitinib as EGFR inhibitor in this study. To inhibit autophagy activity, we used bafilomycin A1 (BFA1), chloroquinine (CQ), and 3-Methyladenine (3-MA). To measure the alteration of cell proliferation following specific treatments, we performed the Cell Counting Kit-8 assay and the clonogenic assay. To examine apoptotic cell death, we conducted flow cytometry using annexin-V/propidium iodide (PI) and western blot analysis. To assess the autophagy activities, we analyzed the expression levels of LC3 and p62/sequestosome-1 (SQSTM1) by immunoblotting and immunocytochemistry. To validate the synergistic effects of autophagy inhibition with EGFR inhibitor, we specifically blocked key autophagy regulatory gene ATG12 by RNA interference, and examined the phenotypic changes. RESULTS: We observed that treatment of Gefitinib triggered the autophagy activities in T24 and J82 human bladder cancer cells, as indicated by upregulation of LC3II and downregulation of P62/SQSTM1 (Fig. 1A-B). Notably, pharmacologic inhibition of autophagy significantly enhanced the anti-cancer effect of EGFR inhibitor as shown by the results of CCK-8 and clonogenic assay (Fig. 1C-D). Moreover, we obtained the similar results of enhanced anti-cancer effects of EGFR inhibitor by suppressing the expression of ATG12 (Fig. 2A-B). CONCLUSIONS: In summary, concomitant inhibition of autophagy activities potentiates the anti-cancer effects of EGFR inhibitor in human bladder cancer cells, indicating a potential therapeutic strategy to treat advanced bladder cancer. Source of Funding: This study was supported by a grant from the Seoul National University Hospital Research Fund (042015-0310).