Integrative genomic and gene-expression analyses have identified amplified onco-genes in B-cell non-Hodgkin lymphoma (B-NHL), but the capability of such technologies to localize tumor suppressor genes within homozygous deletions remains unexplored. Array-based comparative genomic hybridization (CGH) and gene-expression microarray analysis of 48 cell lines derived from patients with different B-NHLs delineated 20 homozy-gous deletions at 7 chromosome areas, all of which contained tumor suppressor gene targets. Further investigation revealed that only a fraction of primary biopsies presented inactivation of these genes by point mutation or intragenic deletion, but instead some of them were frequently silenced by epigenetic mechanisms. Notably, the pattern of genetic and epigenetic inactivation differed among B-NHL subtypes. Thus, the P53-inducible PIG7/LITAF was silenced by homozygous deletion in primary mediastinal B-cell lym-phoma and by promoter hypermethyl-ation in germinal center lymphoma, the proapoptotic BIM gene presented ho-mozygous deletion in mantle cell lym-phoma and promoter hypermethylation in Burkitt lymphoma, the proapoptotic BH3-only NOXA was mutated and preferentially silenced in diffuse large B-cell lym-phoma, and INK4c/P18 was silenced by biallelic mutation in mantle-cell lym-phoma. Our microarray strategy has identified novel candidate tumor suppressor genes inactivated by genetic and epige-netic mechanisms that substantially vary among the B-NHL subtypes. (Blood. 2007; 109:271-280)

CCAAT enhancer-binding protein (CEBP)transcription