María de Guadalupe Chávez-López, Violeta Zúñiga-García, Elisabeth Hernández-Gallegos, Eunice Vera, Carmen Alexandra Chasiquiza-Anchatuña, Marco Viteri-Yánez, Janet Sanchez-Ramos, Efraín Garrido, Javier Camacho

Lung cancer is a major cause of cancer mortality. Thus, novel therapies are urgently needed. Repositioning of old drugs is gaining great interest in cancer treatment. Astemizole is an antihistamine proposed to be repositioned for cancer therapy. This drug targets several molecules involved in cancer including histamine receptors, ABC transporters and the potassium channels Eag1 and HERG. Astemizole inhibits the proliferation of different cancer cells including those from cervix, breast, leukemia and liver. Gefitinib is widely used to treat lung cancer; however, no response or drug resistance occurs in many cases. Here, we studied the combined effect of astemizole and gefitinib on the proliferation, survival, apoptosis and gene and protein expression of Eag1 channels in the human lung cancer cell lines A549 and NCI-H1975. Cell proliferation and survival were studied by the MTT method and the colony formation assay, respectively; apoptosis was investigated by flow cytometry. Gene expression was assessed by real-time polymerase chain reaction (RT-PCR), and protein expression was studied by Western blot analysis and immunocytochemistry. We obtained the inhibitory concentrations 20 and 50 (IC20 and IC50, respectively) values for each drug from the cell proliferation experiments. Drug combination at their IC20 had a superior effect by reducing cell proliferation and survival in up to 80% and 100%, respectively. The drugs alone did not affect apoptosis of H1975 cells, but the drug combination at their IC20 increased apoptosis roughly four times in comparison to the effect of the drugs alone. Eag1 mRNA levels and protein expression were decreased by the drug combination in A549 cells, and astemizole induced subcellular localization changes of the channel protein in these cells. Our in vitro studies strongly suggest that the combination astemizole-gefitinib may be a novel and promising therapy for lung cancer patients.