Lipophilic statins antagonistically alter the major epithelial-to-mesenchymal transition signaling pathways in breast cancer stem-like cells via inhibition of the mevalonate pathway.

Resistance to therapies, recurrence, and metastasis remain challenging issues for breast cancer patients, particularly for triple-negative and breast cancer stem cells. The activation of the epithelial-to-mesenchymal transition (EMT) plays an indispensable role in the poor prognosis of those types. The accumulating proofs indicated that the mevalonate pathway crucially mediates a poor prognosis. Here, the effects of lipophilic 3-hydroxy-3-methyl-glutaryl-coenzyme A inhibitors, atorvastatin, lovastatin, and simvastatin, were investigated on expression and function of a selected profile of EMT-related genes in breast cancer stem-like cells. A nontoxic dose of statins (5 µM for 4 days) significantly (P < 0.05 and >2-fold change) altered expression of 50 of 71 studied genes with a shared cluster of 37 genes that are coding chief operator of signaling pathways in Hippo, Notch, Wnt, proliferation, invasion, angiogenesis, and cell death. They also significantly decreased the levels of Yap/Taz proteins and shifted the expression of vimentin/E-cadherin in favor of induction of differentiation. Statins significantly chemosensitized the treated cells to doxorubicin and also reduced in vitro migration of the cells. Whereas lovastatin and simvastatin significantly decreased the expression of CD44, atorvastatin drastically increased CD24 and caused more wide-ranging impacts. In summary, the statins hold back the process of EMT by the antagonizing of EMT-promoting pathways. High degree of overlapping findings is supportive of the central role of the mevalonate pathway in cancer stem-like cells, but further studies are required to find the optimized chemical structure for the maximum abrogation of orchestrated EMT pathways.

Hybrid Benzoxazole-Coumarin Compounds Induce Death Receptor-Mediated Switchable Apoptotic and Necroptotic Cell Death on HN-5 Head and Neck Cancer Cell Line.

BACKGROUND: Efficacy of multimodality approaches for the treatment of squamous cell cancer of the head and neck has remained unsatisfactory and further advances are critically required. Targeted cell death induction is a novel therapeutic approach that may help to improve clinical management of Head and Neck cancer patients. OBJECTIVE: The potency of novel hybrid benzoxazole-coumarins on the induction of apoptotic and/or necroptotic cell death were evaluated in a Head and Neck carcinoma cell line, HN-5, and a human skin cell line, AGO1522. METHODS: Quantitative toxicity of the synthesized compounds were elucidated by MTT assay, the specific activity of caspase-3 and -9 were measured by the colorimetric method and zVAD was used to block apoptosis. Expression of cell death related genes were studied using quantitative PCR. RESULTS: All three compounds were revealed IC50 value around 51.96±7.15 microM in HN-5 cells which were significantly lower than observed IC50 for AGO1522, 121.93±3.66 microM (p=0.001). Significant increase expression of FAS, FASL and TRIAL were observed in the treated cells with or without pretreatment with zVAD. In the absence of pretreatment, treatment lead to the induction of apoptosis with a significant increase in caspase-3 gene expression and caspase-3 activity without a significant increase in expression or activity of caspase-9 and other components of the intrinsic apoptotic pathway. However, in the zVAD pretreated cells, necroptotic cell death with a significant increase in expression of RIP1, RIP3, and MLKL genes was observed Conclusion: The novel hybrid benzoxazole-coumarins effectively induce Caspase-3 dependent apoptosis in HN-5 cancer cells, but also could circumvent the blockage of apoptotic cell death by induction of necroptosis.