Expression profiling by array in ATLL

Previously, we have shown that an AP-1 family member Fra-2, which is hardly expressed in normal mature T cells, is consistently over-expressed in adult T-cell leukemia/lymphoma (ATLL), and together with JunD, upregulates CCR4 and many other genes including proto-oncogenes c-Myb, MDM2, Bcl-6, and SOX4. SOX4 is frequently overexpressed in many solid tumors and considered to be a potential oncogene. To identify downstream target genes of SOX4 and analyze SOX4 oncogenic pathway in ATLL , we compared gene expression profiles of ST1 cells transfected with SOX4 siRNA or control siRNA using the Affymetrix high density oligonucleotide microarray. The ATL-derived cell line ST1 was transfected with control siRNA or SOX4 siRNA using Nucleofector® (Lonza, Basel, Switzerland). To determine the high-viability of the cells transfected with siRNAs, the cells were counted after 6 h on FACSCalibur (Becton Dickinson, Mountain View, CA) by gating out cells stained with propidium iodide. The transfection efficiency of RNAs was close to 95%, as determined by using fluorescent siRNA (Qiagen). After 48 h, total RNA samples were prepared and confirmed to be of good quality with the Agilent 2100 Bioanalyzer (Agilent Technologies, Waldbronn, Germany). In addition, quantitative PCR confirmed that SOX4 siRNA effectively reduced SOX4 mRNA in ST1 cells.