Primary WWOX phosphorylation and JNK activation during etoposide induces cytotoxicity in HEK293 cells

BACKGROUND AND THE PURPOSE OF THE STUDY Etoposide is an antineoplastic agent used in multiple cancers. It is known that etoposide induce cell death via interaction with topoisomerase II; however, the etopoisde cellular response is poorly understood. Upon etoposide induced DNA damage, many stress signaling pathways including JNK are activated. In response to DNA damage, it has been shown that WWOX, a recently introduced tumor suppressor, can be activated. In this study the activation of WWOX and JNK and their interaction following etoposide treatment were evaluated. MATERIALS AND METHODS HEK293 cells treated with etoposide were lysed in a time course manner. The whole cell lysates were used to evaluate JNK and WWOX activation pattern using Phospho specific antibodies on western blots. The viability of cells treated with etoposide, JNK specific inhibitor and their combination was examined using MTT assay. RESULTS Findings of this study indicate that WWOX and JNK are activated in a simultaneous way in response to DNA damage. Moreover, JNK inhibition enhances etoposide induced cytotoxicity in HEK293. CONCLUSION Taken together, our results indicate that etoposide induces cytotoxicity and WWOX phosphorylation and the cytotoxicty is augmented by blocking JNK pathway.