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Purpose c-Met is an attractive potential target for novel therapeutic inhibition of human cancer, and c-Met tyrosine kinase inhibitors (TKIs) are effective growth inhibitors of various malignancies. However, their mechanisms in anticancer effects are not clear. In the present study,we investigated the possibility that blocking c-Met signaling induces p53-mediated growth inhibition in lung cancer. Materials and Methods The growth inhibitory effects of c-Met TKI (SU11274) on lung cancer cells and a xenograft model were assessed using the MTT assay, flow cytometry, and terminal deoxyribonucleotide transferase-mediated nick-end labeling staining. The role of p53 protein in the sensitivity of c-Met TKI (SU11274) was examined by Western blot analysis and immunohistochemistry. Results SU11274 significantly induced apoptosis in A549 cells with wild-type p53, compared with that in Calu-1 cells with null-type p53. SU11274 increased p53 protein by enhancing the stability of p53 protein. Increased p53 protein by SU11274 induced up-regulation of Bax and PUMA expression and down-regulation of Bcl-2 expression, subsequently activating caspase 3. In p53 knock-out and knock-in systems, we confirmed that SU11274 caused apoptosis through the p53-mediated apoptotic pathway. Likewise, in the A549 xenograft model, SU11274 effectively shrank tumor volume and induced apoptosis via increased p53protein expression. Blocking c-Met signaling increased the level of p53 protein. Conclusion Our finding suggested that p53 plays an important role in SU11274-induced apoptosis, and p53 status seems to be related to the sensitivity to SU11274 in lung cancer.
