GENES, CHROMOSOMES & CANCER 50:996–1009 (2011) t(4;8)(q27;q24) in Hodgkin Lymphoma Cells Targets Phosphodiesterase PDE5A and Homeobox Gene ZHX2 Stefan Nagel, 1 * Bjo ¨rn Schneider, 1 Andreas Rosenwald, 2 Corinna Meyer, 1 Maren Kaufmann, 1 Hans G. Drexler, 1 and Roderick A. F. MacLeod 1 1 Department of Human and Animal Cell Lines, DSMZçGerman Collection of Microorganisms and Cell Cultures, Inhoffenstr. 7B, 38124 Braunschweig,Germany 2 Institute of Pathology,University of Wˇrzburg,Wˇrzburg,Germany Hodgkin/Reed–Sternberg (HRS) cells represent the malignant fraction of infiltrated lymph nodes in Hodgkin lymphoma (HL). Although HRS cells display multiple chromosomal aberrations, few are recurrent and the targeted genes unknown. However, understanding the pathology of HL and developing rational therapies may well require identifying putative deregulated genes. Here, we analyzed the karyotype of the well-defined HL cell line L-1236 by spectral karyotyping and identified multiple abnor- malities, therein, notably t(4;8)(q27;q24) which includes two breakpoint regions previously highlighted in HL. Target genes at 4q27 and 8q24 were shortlisted by high density genomic arrays and fluorescence in situ hybridization. Expression analysis of candidate target genes revealed conspicuous activation of phosphodiesterase PDE5A at 4q27 and inhibition of homeobox gene ZHX2 at 8q24. Treatment of L-1236 with PDE5A-inhibitor sildenafil or with siRNA directed against PDE5A and concomi- tant stimulation with cyclic guanosine monophosphate (cGMP) resulted in enhanced apoptosis, indicating PDE5A as an onco- gene. Expression profiling of L-1236 cells following siRNA-mediated knockdown of ZHX2 showed inhibition of genes regulating differentiation and apoptosis, suggesting tumor suppressor activity of ZHX2. Downstream genes included STAT1 and several STAT1-target genes, indicating activation of STAT1-signaling by ZHX2 as analyzed by RQ-PCR and western blot. Taken together, we haveidentified a novel aberration with recurrent breakpoints in HL, t(4;8)(q27;q24), which activate PDE5A and repress ZHX2, deregulating apoptosis, differentiation, and STAT1-signaling in HL cells. V V C 2011 Wiley Periodicals, Inc. INTRODUCTION Infiltrated lymph nodes (LNs) in Hodgkin lym- phoma (HL) contain a small number of malignant Hodgkin/Reed–Sternberg (HRS) cells and many bystander cells, including activated lymphocytes, plasma cells, and granulocytes (Aldinucci et al., 2011). This situation reflects deregulated activity of interleukins and other signaling molecules in HL. Moreover, expression of the corresponding receptors in HRS cells indicates the presence of autocrine loops, mediating this particular aspect of HL pathology. Accordingly, the escape of immune defense mechanisms represents an important sur- vival strategy of HRS cells which contact diverse types of immune cells (Aldinucci et al., 2011). Additionally, aberrant activity of NFkB transcrip- tion factors is involved in the survival of the malig- nant cells and multiple mechanisms have been described which activate NFkB factors in HL cells, including amplification of REL, and mutation of IkB and of A20 (Ku ¨ ppers, 2009). A hallmark of HRS cells is constitutive activity of signaling-pathways which transmit receptor- activities via MAPK, including ERK1/2 and ERK5, and via PI3K (Kube et al., 2001; Zheng et al., 2003; Nagel et al., 2005, 2007). Signal trans- ducer and activator of transcription (STAT) pro- teins are intracellular signaling molecules which shuttle between the cytoplasm and the nucleus on phosphorylation/activation by certain Janus ki- nases (JAKs) (Imada and Leonard, 2000). Several aberrantly activated STAT proteins are present in HRS cells, including STAT3, STAT5, and STAT6 (Kube et al., 2001; Hinz et al., 2002; Skin- nider et al., 2002; Scheeren et al., 2008). Chromo- somal amplification of JAK2 may represent just one mechanism enforcing activation of STAT3- signaling (Joos et al., 2000). In contrast, STAT1- signaling promotes apoptosis and is inhibited by STAT6-signaling (Baus et al., 2009). HRS cells originate from B-cells, displaying deregulated differentiation programs. Main tran- scription factors important for the B-cell develop- ment are absent or inactivated, resulting in B-cells *Correspondence to: Stefan Nagel, Department of Human and Animal Cell Lines, DSMZ, Inhoffenstr. 7B, 38124 Braunschweig, Germany. E-mail: sna@dsmz.de yPresent address: Institute of Pathology, University of Rostock, Rostock, Germany. Received 1 June 2011; Accepted 20 July 2011 DOI 10.1002/gcc.20920 Published online 30 August 2011 in Wiley Online Library (wileyonlinelibrary.com). V V C 2011 Wiley Periodicals, Inc.