EphA2 inhibition suppresses proliferation of small-cell lung cancer cells through inducing cell cycle arrest.

Small-cell lung cancer (SCLC) is characterized by one of neuroendocrine tumors, and is a clinically aggressive cancer due to its rapid growth, early dissemination, and rapid acquisition of multidrug resistance to chemotherapy. Moreover, the standard chemotherapeutic regimen in SCLC has not changed for three decades despite of the dramatic therapeutic improvement in non-SCLC. The development of a novel therapeutic strategy for SCLC has become a pressing issue. We found that expression of Eph receptor A2 (EphA2) is upregulated in three of 13 SCLC cell lines and five of 76 SCLC tumor samples. Genetic inhibition using siRNA of EphA2 significantly suppressed the cellular proliferation via induction of cell cycle arrest in SBC-5 cells. Furthermore, small molecule inhibitors of EphA2 (ALW-II-41-27 and dasatinib) also exclusively inhibited proliferation of EphA2-positive SCLC cells by the same mechanism. Collectively, EphA2 could be a promising candidate as a therapeutic target for SCLC.