Studies on abnormalities of membrane receptor signaling in malignant lymphoma cells as a basis of diagnosis and treatment

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(1)Analysis of CD30 promoter activation :We demonstrated that the constitutive overexpression CD30 activate ERK1/2 MAPK pathway, and induces JunB expression, which is a common characteristic of neoplastic. Activation of NF-kB results from "ligand-independent activation" of overexpressed CD30 on the Hodgkin/Reed- Sternberg (H-RS) cells, and that inhibition of CD30 signaling by transduction of a dominant negative decoy CD30 that lacks the cytoplasmic region induced apoptotic cell death of H-RS cells (Horie et al., Oncogene 21, 2493, 2002). We showed that cytoplasmic aggregation of TRAF2 and TRAF5 proteins represents constant signaling of CD30 ( Horie et al., Am J Pathol 160, 1647, 2002). We demonstrated that the AP-1 binding sequence located near the microsatellite counteracts the suppressive effects of the microsatellite on the CD30 promoter activity (Watanabe et al., Am J Pathol 163, 633, 2003). We showed that p80NPM-ALK inhibits ligand-independent signal transduction by overexpressed … More CD30 in ALCL cells though sequestration of TRAF proteins in the complex of NPM-ALK and wild type NPM (Horie et al., Cancer Cell 5, 353, 2004).(2)Expression profile analysis of primary ATL cells :We characterized the expression profile of primary ATL cells using the synthetic DNA array system and samples of 16 ATL cases and 11 healthy volunteers. The results revealed 108 overexpressed genes and 250 downregulated genes. Based on the results, we are now preparing a detection system of ATL cells in the PBMC using multiple real-time PCR analysis of samples. A pilot study clearly detected ATL cells in a sample derived from a carrier considered to be an asymptomatic carrier, which was confirmed by monoclonal pattern in subsequent Southern blot analysis.(3)Studies on the target genes of NF-kB :Expression profile analyses were done by CodeLink system using cell lines with constitutive activation of NF-kB and treatment by DHMEQ. The results revealed more than 1,000 genes that are up- or down-regulated more than two-fold by DHMEQ treatment. Up-regulated genes included these involved in proapoptotic function, and down-regulated genes included those involved in anti-apoptotic function. Furthermore, many genes were revealed to be target genes of NF-kB signaling (a part of these data were used in the manuscript of BLOOD 106, 2642, 2005).(4)Basic studies on the molecular targeted therapy by NF-kB inhibition using DHMEQ :Anti-tumor activity of DHMEQ against ATL, CLL and Hodgkin's lymphoma was tested by in vitro experiments and in vivo xenograft model using a SCID mice system. As to ATL, DHMEQ was shown to be able to purge carrier's PBMC of HTLV-1-infected but not transformed cells (BLOOD 106, 2642, 2005). DHMEQ was also effective against CLL cells, and showed synergistic effect with fludarabine when used in combination (Leukemia 20, 800, 2006). DHMEQ showed anti-tumor activity against H-RS cells in vitro and in vivo (Cancer Res, submitted). Less