Afatinib triggers a Ni²⁺‐resistant Ca²⁺ influx pathway in A549 non‐small cell lung cancer cells

Abstract

Afatinib is used to treat non‐small cell lung cancer cells (NSCLC), and its mechanism involves irreversible inhibition of epidermal growth factor receptor (EGFR) tyrosine kinase. In this study, we examined if afatinib had cytotoxic action against NSCLC other than inhibition of tyrosine kinase. Afatinib (1–30 μM) caused apoptotic death in A549 NSCLC in a concentration‐dependent manner. Afatinib triggered Ca2+ influx without causing Ca2+ release, and the Ca2+ influx was unaffected by sodium orthovanadate (SOV, an inhibitor of tyrosine phosphatase), suggesting that afatinib‐triggered Ca2+ response was unrelated to its inhibition of tyrosine kinase. Addition of afatinib also promoted Mn2+ influx. Ca2+ influx triggered by afatinib was resistant to SKF96365 and ruthenium red (two general blockers of TRP channels) and, unexpectedly, Ni2+ (a non‐specific Ca2+ channel blocker). Afatinib caused an increase in mitochondrial Ca2+ level, an initial mitochondrial hyperpolarization (4 h) and followed by mitochondrial potential collapse (24–48 h). Afatinib‐induced cell death was slightly but significantly alleviated in low extracellular Ca2+ condition or under pharmacological block of mitochondrial permeability transition pore (MPTP) opening by cyclosporin A. Therefore, in addition to tyrosine kinase inhibition as a major anti‐cancer mechanism of afatinib, stimulation of an atypical Ca2+ influx pathway, mitochondrial Ca2+ overload, and potential collapse in part contribute to afatinib‐induced cell death.

Weekly Afatinib in the Treatment of Advanced Non-small Cell Lung Cancer with EGFR-G719C Mutation Followed by Lobectomy: A Case Report

“…A finding by Tsai and Tien indicated that Afatinib can lead to mitochondrial dysfunction in NSCLC cells, particularly affecting the Ca 2+ influx pathway and leading to mitochondrial Ca 2+ overload (14). Recent evidence supporting the role of mitochondrial metabolism in cancer survival could potentially justify the favorable response to Afatinib in our patient (15).…”