Treatment with DHMEQ, however, did not change the expression levels of ERK, JNK, and p.To additionally assess the relevance of the observed MAPK pathway activation to the effects of DHMEQ, we investigated whether the inhibition of MAPK pathways modulates cell survival after treatment.To analyze individual MAPK signaling cascades, we used specific inhibitors of MEK. We found that neither the inhibition of MEK nor that of p had any detectable effect on thyroid carcinoma cell viability after treatment with DHMEQ. In contrast, however, incubation with SP suppressed DHMEQ cytotoxity in each of the cell lines tested.One of the possible explanations of these observations is that DHMEQ causes a transient NFB inhibition, and p DNA binding was restored in to hours after a singledose treatment.Thus, our data suggest that downregulation of IAP proteins by DHMEQ can affect the balance between pro and antiapoptotic signals in thyroid cancer cells and trigger apoptosis.Effects of MAPK family inhibitors on DHMEQ cytotoxity in FRO cells.Plates were incubated for hours, and the cell number was assessed by the watersoluble tetrazolium saltbased assay; bars, mean SD.As a result of DHMEQ treatment, we observed the activation of caspases and Revefenacin apoptosis in cancer cells in vitro and in vivo.The mechanism of apoptosis after the NFB inhibition has been largely investigated.It has been shown that NFB activated the group of genes, the products of which suppressed the apoptotic process at the level of caspase activation. The cIAP, cIAP, and XIAP can bind and inhibit caspase and caspase, thus contributing to tumor cell resistance to cytotoxic agents. However, whereas NFB inhibition by SN substantially retarded cancer cell growth, it did not trigger massive cell death, and only combined treatment with ionizing radiation enhanced cell killing both in culture and in vivo.Similar data on adjuvant treatment have been obtained in other solid tumors. These findings suggested that NFB inhibition per se did not trigger apoptosis but Thujone played an apoptosispermissive role in cells treated with cytokines, chemotherapeutic drugs, or by ionizing radiation.In the present study, however, DHMEQ inhibited NFB signaling at the level of nuclear translocation similarly to SN and in parallel induced strong apoptotic cell death in tumor cells.This prompted us to investigate whether DHMEQ could activate additional proapoptotic signaling mechanisms and, hence, initiate apoptotic processes.JNK activation has been shown to be one of the key proapoptotic factors in mitochondriadependent death pathways, and the duration of this activation is critical for this role of JNK.Thus, our data suggest that JNK activation is necessary to promote apoptosis in thyroid cancer cells in the absence of NFB signaling and that the dose range of DHMEQ, within which JNK inhibition prevents cell death, denotes an apoptotic range of DHMEQ and correlates with our findings via FACS and procaspase cleavage analysis.In conclusion, our results show that thyroid carcinoma cells can be effectively killed by a novel NFB inhibitor, DHMEQ, both in culture and in vivo.The high efficiency of DHMEQ is most likely because of the simultaneous upregulation of cellular proapoptotic signaling, such as sustained JNK activation and potent inhibition of one of the principal antiapoptotic switches, NFB.