Transcription profiling of human adult T-cell leukemia/lymphoma (ATL) patients

Abstract: Adult T-cell leukemia/lymphoma (ATL) is an aggressive and fatal disease. We have examined 18 ATL patient samples using Affymetrix HG-U133A2.0 arrays. Using the BRB array program, we identified genes differentially expressed in leukemia cells compared to normal lymphocytes. Several unique genes were identified that were overexpressed in leukemia cells including TNFSF11, RGS13, MAFb, CSPG2, C/EBPalpha and TCF4. 200 of the most highly overexpressed ATL genes were analyzed by the PathwayStudio 4.0 program. ATL leukemia cells were characterized by an increase in genes linked to "central" genes CDC2/cyclin B1, SYK/LYN, PCNA and BIRC5. Because of its potential therapeutic importance, we focused our studies on the regulation and function of BIRC5, whose expression was increased in 13 of 14 leukemia samples. TCF4 reporter assays and transfection of DN-TCF4 demonstrated that TCF4 regulates BIRC5 gene expression. Functionally, transfection of ATL cells wi BIRC5 shRNA decreased BIRC5 exprression and cell viability 80%. Clinical treatment of ATL patients with Zenapax or bortezomib decreased BIRC5 expression and cell viability. These experiments represent the first direct experimental evidence that BIRC5 plays an important role in ATL cell viability and provides important insight into ATL genesis and potential targeted therapies. Experiment Overall Design: Gene expression profiles of 7 control and 18 ATL patient samples were analyzed using Affymetrix HG-U133A2.0 arrays.