Everolimus enhances cellular cytotoxicity of lapatinib via the eukaryotic elongation factor-2 kinase pathway in nasopharyngeal carcinoma cells.

BACKGROUND: Nasopharyngeal carcinoma (NPC) has a high relapse and metastatic rates; hence, development of new therapeutics is an immediate requirement. Lapatinib and everolimus have been demonstrated to be effective in the treatment of several carcinomas. This preclinical study aimed to investigate the effect and mechanism of lapatinib combined with everolimus on NPC cells. METHODS: The Cell Counting Kit 8 and colony formation assay were used to detect the effect of lapatinib alone or lapatinib combined with everolimus on the growth and proliferation of cells. Apoptosis was tested by flow cytometry and was further confirmed by western blot. The targets of lapatinib and the effects of lapatinib or everolimus on the eukaryotic elongation factor-2 (eEF-2) kinase pathway were analyzed by western blot, which also evaluated autophagy activity. RESULTS: Lapatinib inhibited the cellular viability and colony formation in NPC cells. At 24-72 h, the average half maximal inhibitory concentration (IC50) values of lapatinib were ranging from 3 to 5 µM. This study further found that lapatinib induced both apoptosis and autophagy in NPC cells, and this autophagic activity was described as type II programmed cell death via an eEF-2 kinase-dependent pathway. In addition, augmentation of lapatinib-induced autophagy by mammalian target of rapamycin (mTOR) inhibitor everolimus enhanced the cytocidal effect of lapatinib in NPC cells via the mTOR/S6 kinase/eEF-2 kinase pathway. CONCLUSION: This study reveals that everolimus can sensitize NPC cells to lapatinib by the activation of eEF-2 kinase and provides a potential model of combination therapy.

Inhibition of eEF-2 kinase sensitizes human nasopharyngeal carcinoma cells to lapatinib-induced apoptosis through the Src and Erk pathways.

BACKGROUND: Previous studies have reported that eEF-2 kinase is associated with tumour cell sensitivity to certain therapies. In the present study, we investigated the relationship between eEF-2 kinase and lapatinib, a dual inhibitor of EGFR and HER-2, in nasopharyngeal carcinoma (NPC) cells. METHODS: The effect of treatment on the growth and proliferation of NPC cells was measured by three methods: cell counting, crystal violet staining and colony counting. Apoptosis was evaluated by flow cytometry to determine Annexin V-APC/7-AAD and cleaved PARP levels, and the results were further confirmed by Western blot analysis. The expression of eEF-2 kinase and the impacts of different treatments on different signalling pathways were analysed by Western blot analysis. RESULTS: The expression of eEF-2 kinase was significantly associated with NPC cell sensitivity to lapatinib. Therefore, suppression of this kinase could increase the cytocidal effect of lapatinib, as well as reduce cell viability and colony formation. Furthermore, inhibition of eEF-2 kinase, by either RNA interference (eEF-2 kinase siRNA or shRNA) or pharmacological inhibition (NH125), enhanced lapatinib-induced apoptosis of NPC cells. The results also showed that lapatinib combined with NH125 had a synergistic effect in NPC cells. In addition, mechanistic analyses revealed that downregulation of the ERK1/2 and Src pathways, but not the AKT pathway, was involved in this sensitizing effect. CONCLUSIONS: The results of this study suggest that targeting eEF-2 kinase may improve the efficacy of therapeutic interventions such as lapatinib in NPC cells.

Phase II trial of docetaxel combined with nedaplatin for patients with recurrent and metastatic nasopharyngeal carcinoma.

PURPOSE: This Phase II trial was designed to evaluate the efficacy and safety of docetaxel combined with nedaplatin as first-line treatment for patients with recurrent or metastatic nasopharyngeal carcinoma. METHODS: In this multicenter Phase II trial, the patients were treated with intravenous docetaxel (75 mg/m(2), day 1) and nedaplatin (80 mg/m(2), day 1), each cycle repeated every 3 weeks for two cycles at least. RESULTS: From January 2010 to November 2013, a total of 78 patients were recruited in this trial. Among them, 73 patients were assessable for response. The treatment was well tolerated. The main hematological adverse event was neutropenia. A total of 12 patients (15.4%) had grade 3 or grade 4 neutropenia. Grade 3 anemia was observed in six patients (7.7%) and no grade 3/4 thrombocytopenia was observed. No Grade 3/4 non-hematological toxicity was observed. There were five complete response (6.8%), 43 partial responses (58.9%), and the overall response rate was 65.8% (95% confidence interval [CI], 48.7%-81.2%). With a median follow-up period of 18.6 months, the median time to progression was 7.9 months (95% CI, 4.2-10.8 months), median overall survival was 15.7 months (95% CI, 11.6-18.5 months). CONCLUSION: Docetaxel combined with nedaplatin offers a satisfactory clinical activity and an acceptable safety profile as first-line chemotherapy for patients with recurrent and metastatic nasopharyngeal carcinoma.