Abstract:
Lung cancer is a common cancer disease that contributes as a major cause of cancer related death. The oncoprotein, c-Myc plays a major role in oncogenic malignancies. It has been shown that the up—regulated c-Myc relates with aggressiveness of cancers and treatment failure. In this study, we purposed N, N-bis (5-ethyl-2-hydroxybenzyl) methylamine (EMD), a benzoxazine dimer to be a novel c-Myc targeting compound and displayed evidence presenting the potential effect of EMD on c-Myc degradation in human lung cancer cells. EMD exhibited cytotoxicity to lung cancer cells through apoptosis induction. EMD dramatically eliminated c-Myc in the cells and initiated caspase-dependent apoptosis cascade. Cycloheximide chase assay showed that half-life of c-Myc protein was shortened by EMD. MG132, a potent selective proteasome inhibitor, could restore the c-Myc level conveying the involvement of ubiquitin-mediated proteasomal degradation in the process. In addition, immunoprecipitation analysis demonstrated that EMD significantly increased c-Myc-ubiquitin complex formation. We further verified that EMD strongly decreased c-Myc protein levels in primary lung cancer cells. In addition, we also purposed that EMD has an anti-metastatic effect. Metastasis is the process that cancer cells detach from the original site to form a new tumor at distant site through blood or lymphatic vessels. Cell migration is a part of the metastasis cascade which regulated by several signals. Integrin signaling involves in cell survival and activation of cell migration. EMD at non-toxic concentrations reduced filopodia formation and cell migration. In addition, EMD significantly inhibited growth and survival of detached lung cancer cells. Moreover, EMD strongly decreased integrin b3 while other evaluated integrins, b1 and a5 were not altered. Other downstream of integrin signaling such as active focal adhesion kinase (FAK) and active protein kinase B (Akt) were significantly decreased after EMD treatment. Altogether, we identified EMD as a novel potential compound for lung cancer treatment.
