Crizotinib Inhibits Viability, Migration, and Invasion by Suppressing the c-Met/PI3K/Akt Pathway in the Three-Dimensional Bladder Cancer Spheroid Model

We aimed to evaluate the therapeutic potential of crizotinib, a broad-spectrum tyrosine kinase inhibitor against bladder cancer (BC) cells, based on a three-dimensional (3D) cell culture system. After proliferating cell masses (spheroids) using T24 cisplatin-naïve and T24R2 cisplatin-resistant human BC cell lines, the spheroids were exposed to various crizotinib concentrations in order to derive an ideal crizotinib concentration to suppress cell survival, migration, and invasion. Crizotinib suppressed cell proliferation, migration, and invasion in both T24 and T24R2 BC cell lines under a 3D spheroid model, which was more appropriate than the conventional two-dimensional cell culture model. Real-time quantitative polymerase chain reaction analysis revealed a reduced expression of <i>E-cadherin</i> and an enhanced expression of <i>vimentin</i>, suggesting EMT suppression and the subsequent suppression of tumor aggressiveness following crizotinib administration. Meanwhile, the expressions of apoptosis-related genes increased. Western blot analysis revealed that the expression levels of <i>phosphorylated mesenchymal-epithelial transition factor (c-Met)</i> and <i>phosphorylated Akt</i> decreased following crizotinib administration, suggesting that the antitumor effect of crizotinib can be associated with the inhibition of the phosphorylated activation of the <i>c-Met</i>/<i>PI3K</i>/<i>Akt</i> pathway. Crizotinib showed a potential antitumor effect on both cisplatin-naïve and cisplatin-resistant human BC cells, likely through <i>c-Met</i>-induced <i>PI3K</i>/<i>Akt</i> pathway inhibition.