Abstract
Neuron-specific enolase (NSE) is generally considered as a marker for diagnosis and evaluation of the response to therapy in small cell lung cancer (SCLC). However, the role of NSE in the progression of SCLC remains to be elucidated. In the present study, the functions of NSE in SCLC, in addition to the potential mechanisms, were investigated using a loss-of-function approach with NSE-targeting small interfering (si)RNA. The knockdown of NSE markedly decreased the proliferation of NCI-H209 cells, as indicated by MTT assay (P<0.05). Furthermore, the silencing of NSE resulted in the formation of smaller and fewer colonies compared with that in the control group (P<0.001). Flow cytometric analysis indicated that the silencing of NSE resulted in a decreased S-phase population among NCI-H209 cells (P<0.05). Transwell assay demonstrated that the silencing of NSE suppressed the migration of NCI-H209 cells (P<0.001). NCI-H209 cells transfected with NSE siRNA-1 or negative control were collected and the protein levels of metastasis-associated genes were detected using western blot analysis. The results indicated that the knockdown of NSE led to downregulation of the pro-metastatic gene vascular endothelial growth factor (VEGF; P<0.05) and the upregulation of metastasis suppressor genes NM23 and E-cadherin (P<0.05). Taken together, the results of the present study demonstrated that the silencing of NSE suppressed the migration, proliferation and colony formation ability of SCLC cells and decreased the S-phase population. In addition, the knockdown of NSE resulted in the upregulation of E-cadherin and NM23 and the downregulation of VEGF. Collectively, these results indicated that intracellular NSE may have an important role in the progression of SCLC.