Characterization of 8p21.3 chromosomal deletions in B-cell lymphoma: TRAIL-R1 and TRAIL-R2 as candidate dosage-dependent tumor suppressor genes

Deletions of chromosome 8p are a recurrent event in B-cell non-Hodgkin lymphoma (B-NHL), suggesting the presence of a tumor suppressor gene. We have characterized these deletions using comparative genomic hybridization to microarrays, fluorescence in situ hybridization (FISH) mapping, DNA sequencing, and functional studies. A minimal deleted region (MDR) of 600 kb was defined in chromosome 8p21.3, with one mantle cell lymphoma cell line (Z138) exhibiting monoallelic deletion of 650 kb. The MDR extended from bacterial artificial chromosome (BAC) clones RP11-382J24 and RP11-109B10 and included the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene loci. Sequence analysis of the individual expressed genes within the MDR and DNA sequencing of the entire MDR in Z138 did not reveal any mutation. Gene expression analysis and quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) showed down-regulation of TRAIL-R1 and TRAIL-R2 receptor genes as a consistent event in B-NHL with 8p21.3 loss. Epigenetic inactivation was excluded via promoter methylation analysis. In vitro studies showed that TRAIL-induced apoptosis was dependent on TRAIL-R1 and/or -R2 dosage in most tumors. Resistance to apoptosis of cell lines with 8p21.3 deletion was reversed by restoration of TRAIL-R1 or TRAIL-R2 expression by gene transfection. Our data suggest that TRAIL-R1 and TRAIL-R2 act as dosage-dependent tumor suppressor genes whose monoallelic deletion can impair TRAIL-induced apoptosis in B-cell lymphoma

A framework for the development of effective anti-metastatic agents

Most cancer-related deaths are a result of metastasis, and thus the importance of this process as a target of therapy cannot be understated. By asking ‘how can we effectively treat cancer?’, we do not capture the complexity of a disease encompassing >200 different cancer types — many consisting of multiple subtypes — with considerable intratumoural heterogeneity, which can result in variable responses to a specific therapy. Moreover, we have much less information on the pathophysiological characteristics of metastases than is available for the primary tumour. Most disseminated tumour cells that arrive in distant tissues, surrounded by unfamiliar cells and a foreign microenvironment, are likely to die; however, those that survive can generate metastatic tumours with a markedly different biology from that of the primary tumour. To treat metastasis effectively, we must inhibit fundamental metastatic processes and develop specific preclinical and clinical strategies that do not rely on primary tumour responses. To address this crucial issue, Cancer Research UK and Cancer Therapeutics CRC Australia formed a Metastasis Working Group with representatives from not-for-profit, academic, government, industry and regulatory bodies in order to develop recommendations on how to tackle the challenges associated with treating (micro)metastatic disease. Herein, we describe the challenges identified as well as the proposed approaches for discovering and developing anticancer agents designed specifically to prevent or delay the metastatic outgrowth of cancer

A framework for the development of effective anti-metastatic agents

Most cancer-related deaths are a result of metastasis, and thus the importance of this process as a target of therapy cannot be understated. By asking ‘how can we effectively treat cancer?’, we do not capture the complexity of a disease encompassing >200 different cancer types — many consisting of multiple subtypes — with considerable intratumoural heterogeneity, which can result in variable responses to a specific therapy. Moreover, we have much less information on the pathophysiological characteristics of metastases than is available for the primary tumour. Most disseminated tumour cells that arrive in distant tissues, surrounded by unfamiliar cells and a foreign microenvironment, are likely to die; however, those that survive can generate metastatic tumours with a markedly different biology from that of the primary tumour. To treat metastasis effectively, we must inhibit fundamental metastatic processes and develop specific preclinical and clinical strategies that do not rely on primary tumour responses. To address this crucial issue, Cancer Research UK and Cancer Therapeutics CRC Australia formed a Metastasis Working Group with representatives from not-for-profit, academic, government, industry and regulatory bodies in order to develop recommendations on how to tackle the challenges associated with treating (micro)metastatic disease. Herein, we describe the challenges identified as well as the proposed approaches for discovering and developing anticancer agents designed specifically to prevent or delay the metastatic outgrowth of cancer

Five CCAAT-enhancer-binding-protein gene family members are deregulated by the immunoglobulin heavy chain locus in B-cell precursor acute lymphoblastic leukaemia

Chromosomal translocations lead to oncogene activation in a significant number of haematological malignancies. Those involving the immunoglobulin heavy chain locus, IGH, at chromosome band 14q32 are frequently observed in B-cell malignant proliferation. A small number have been described in B-cell precursor acute lymphoblastic leukaemia (BCP-ALL). However, their biological and clinical significance is currently unknown. Detailed fluorescence in situ hybridisation (FISH) and molecular studies were carried out on a series of BCP-ALL patients with chromosomal abnormalities involving 14q32. Novel and recurrent translocations affecting different chromosomes were highlighted. Refined FISH mapping identified putative IGH partner genes at, or flanking, the translocation breakpoints. Four translocations: two previously reported, t(14;19)(q32;q13), t(8;14)(q11;q32), and two novel, t(14;14)(q11;q32)/ inv(14)(q11q32) and t(14;20)(q32;q13), were identified. Molecular analyses showed that four different members of the CAATT enhancer binding protein (CEBP) gene family were involved: CEBPA (19q13, n59), CEBPD (8q11, n58), CEBPE (14q11, n53) and CEBPB (20q13, n52). One patient with a t(14;19)(q32;q13) was observed to involve the fifth family member CEBPG (19q13, n51). Breakpoints were located within the 30 untranslated region (UTR) of CEBPA and either 30 UTR or 50 of CEBPE, whereas breakpoints in 8q11 were B30 kb centromeric of CEBPD. Where material was available, over-expression of target genes was shown by quantitative real-time PCR. Overall, this study has demonstrated for the first time the involvement of five members of the same gene family in a single subtype of haematological disease. It has indicated that transcriptional upregulation of CEBP gene family members, by juxtaposition to IGH, is important in BCP-ALL: a mechanism in complete contrast to that involving CEPBA in acute myeloid leukaemia

Characterization of 8p21.3 chromosomal deletions in B-cell lymphoma: TRAIL-R1 and TRAIL-R2 as candidate dosage-dependent tumor suppressor genes

Deletions of chromosome 8p are a recurrent event in B-cell non-Hodgkin lymphoma (B-NHL), suggesting the presence of a tumor suppressor gene. We have characterized these deletions using comparative genomic hybridization to microarrays, fluorescence in situ hybridization (FISH) mapping, DNA sequencing, and functional studies. A minimal deleted region (MDR) of 600 kb was defined in chromosome 8p21.3, with one mantle cell lymphoma cell line (Z138) exhibiting monoallelic deletion of 650 kb. The MDR extended from bacterial artificial chromosome (BAC) clones RP11-382J24 and RP11-109B10 and included the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene loci. Sequence analysis of the individual expressed genes within the MDR and DNA sequencing of the entire MDR in Z138 did not reveal any mutation. Gene expression analysis and quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) showed down-regulation of TRAIL-R1 and TRAIL-R2 receptor genes as a consistent event in B-NHL with 8p21.3 loss. Epigenetic inactivation was excluded via promoter methylation analysis. In vitro studies showed that TRAIL-induced apoptosis was dependent on TRAIL-R1 and/or -R2 dosage in most tumors. Resistance to apoptosis of cell lines with 8p21.3 deletion was reversed by restoration of TRAIL-R1 or TRAIL-R2 expression by gene transfection. Our data suggest that TRAIL-R1 and TRAIL-R2 act as dosage-dependent tumor suppressor genes whose monoallelic deletion can impair TRAIL-induced apoptosis in B-cell lymphoma