Background  The treatment of patients with small cell lung cancer (SCLC) is based on chemotherapy. However, the treatment is limited by the development of drug resistance. Emodin has been shown to exhibit an anti-cancer effect. But the molecular mechanism remains unclear. This study was conducted to investigate the effect of emodin on the gene expression profile changes in SCLC NCI-H446 cells.
Methods  NCI-H446 cells were treated with emodin and cell viability was determined by MTT assay. Cell apoptosis was determined by both flow cytometry and caspase-3 activity assay. The effect of emodin on the gene expression profile of NCI-H446 cells was analyzed using cDNA microarray. Semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was used to validate the microarray results.
Results  Emodin suppressed viability, induced apoptosis and changed cell cycle of NCI-H446 cells. Among the 1262 genes, 10 genes were up-regulated and 8 genes were down-regulated more than 2 folds in NCI-H446 cells when compared with the control cells after treatment with emodin for 12 hours, while 12 genes were up-regulated and 24 genes were down-regulated after treatment with emodin for 24 hours. These genes were involved in metabolism, signal transduction, transcription regulation, cytoskeleton organization, immune response, transport, protein synthesis, cell cycle control, cell adhesion and RNA processing. The RT-PCR results were consistent with those obtained by the microarray.
Conclusions  Emodin affects the expression of genes involved in various cellular functions and plays important roles in cell apoptosis, tumor metastasis and chemotherapy-resistance, which suggests emodin might become an effective chemopreventive or chemotherapeutic agent for SCLC.