Strong expression of neuron restrictive silencer factor (NRSF) has been observed in many aggressive types of cancer cells and mature neurons. However, the function of the neuron restrictive silencer element (NRSE)/NRSF system in KB human oral cancer cells is unknown. Findings from previous studies in our lab have demonstrated the importance of NRSF as a factor in regulationof cell proliferation of KB human oral cancer cells. Treatment of KB cells with NRSF siRNA resulted in signifi cant inhibitionof cell growth through repression of NRSF expression. In this study, in order to understand the NRSE/NRSF regulatory network in KB cells, we performed microarray analysis in KB cells treated with NRSF specifi c targeted siRNA. The expression profi les of several genes were further validated in KB cells treated with NRSF siRNA. Results of microarray analysis showed upregulation of 117 genes and down-regulation of 215 genes in KB cells treated with NRSF siRNA. Most of the up-regulated genes were involved in signal transduction, cell communication, cell cycle, and apoptosis;down-regulated genes were involved in RNA processing, neurogenesis, transcription factor activity, and synaptogenesis. NRSF is known as a transcriptional repressor for silencingof neuronal genes; however, according to our data, treatment of KB cells with NRSF siRNAresulted in down-regulation of more than 200 genes. As a result, genes identifi ed in this screen represent a novel control pathway via NRSF expression in KB oral cancer cells. Further investigation will be needed in order to defi ne the mechanism of gene regulation by expression of NRSF in KB human oral cancer cells.

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