Abstract: Objective To investigate the role of homeobox gene A5 (HOXA5) in multidrug resistance of human small cell lung
cancer (SCLC) cells and the possibility of using HOXA5 as the therapeutic targets for SCLC treatment. Methods We examined
HOXA5 mRNA and protein expressions in chemosensitive human SCLC cells (H69) and the multidrug-resistant SCLC cells
(H69AR) using quantitative real-time PCR and immunoblotting. HOXA5 expression was then enhanced or suppressed by
transfection of the cells with HOXA5 expression plasmids or small interference RNA (siRNA), and the chemosensitivity of
transfected cells to cisplatin (DDP) and etoposide (VP-16) was evaluated using cell counting kit-8 (CCK8) assay. Results H69
cells showed a 8.99-fold higher expression of HOXA5 than H69AR cells. HOXA5 knockdown caused obvious reductions in the
chemosensitivity of H69 cells to DDP and VP-16 with increased cells in G0/G1 phase; conversely, HOXA5 enhancement
resulted in an increased sensitivity of H69AR cells to DDP and VP-16. Conclusion HOXA5 may play an important role in
multidrug resistance of SCLC and can be a potential therapeutic target in clinical treatment of SCLC.