RADIOBIOLOGY DIVISION

8.RADIOBIOLOGY DIVISION

　Current research in Radiobiology Division focuses on the positional cloning of disease genes, especially of leukemia- related genes, and tumor suppressor genes. Functional analyses of several tumor- associated gene products including AML1 and the chimeric transcription factors AML1- MTG8 and FUS- ERG are also ongoing.
Functional Analysis of Leukemia-associated Gene Products

　The FUS(TLS)- ERG chimeric protein associated with t(16;21)acute myeloid leukemia is structurally similar to the Ewing's sarcoma chimeric transcription factor EWS- ERG. Both FUS- ERG and EWS- ERG could induce anchorage- independent proliferation of NIH 3T3 cells. However, only FUS- ERG was able to inhibit the differentiation into neutrophhils of a mouse myeloid precursor cell line L- G and induce its granulocyte colony- stimulating factor- dependent growth. Analysis of several deletion mutants of FUS- ERG indicated that the N- terminal region of FUS contains two independent functional domains named TR1 and TR2 required for the NIH 3T3 and L- G transformation. Three cellular genes whose expression was altered by ectopic expression of FUS- ERG were identified, and they were found to be regulated in either a TR1- dependent or TR2- dependent manner. These results suggest that FUS- ERG may activate two independent oncogenic pathways during the leukemogenic process by simultaneously modulating the expression of two different groups of genes.⁽¹⁴⁴⁾
Genome Analysis and Genetic Alterations in Human Cancers

　Human chromosome 11q23.2 has been suspected to contain a tumor suppressor gene(s)whose deletion is associated with cancer of the lung and breast, and with neuroblastoma. To analyze the genomic structure and to isolate a candidate tumor suppressor gene from this region, we constructed a 2- Mb sequence- ready contig map ⁽¹⁴⁵⁾ using detailed physical maps.⁽¹⁴⁶⁾ The map comprises a contig of 24 overlapping P1, BAC, and PAC clones. To isolate gene fragments from the region, we performed direct cDNA library screening, exon trapping, EST mapping, and genomic sequencing using the P1, BAC, and PAC clones. Sequence analysis of 5 clones, which spans 23%of the region, and extensive gene scanning along the entire region revealed that the region is extraordinarily rare in genes, but we identified one ubiquitously expressed novel gene and one testis- specific gene fragment. The novel gene, which we call IGFS4 (immunoglobulin superfamily), is transcribed as a 1.6- or 4.4- kb RNA encoding a 442- amino- acid protein. It shares strong homology with mouse IGSF- B12 and the cell adhesion molecules NCAM1 and MCAM2 within their Ig- like C2- type domains. The IGSF4 gene, a novel gene that is located in the common loss of heterozygosity region, possesses a number of interesting features and may be a good candidate tumor suppressor gene.⁽¹⁴⁵⁾
　In a survey of childhood therapy- related acute leukemia/myelodysplastic syndrome (t- AML/MDS)in Japan, 11p15 translocations were found in 5 (6%)of 81 children with t- AML/MDS. Also, t(11;17)(p15;q21), t(11;12)(p15;q13), t(7;11)(p15;p15), inv(11)(p15q22), and add (11)(p15)were found in one patient. Southern blotting and/or RT- PCR analyses revealed rearrangements of the NUP98 gene in tumor samples of all five patients.⁽¹⁴⁷⁾ This survey suggests that t- AML/MDS with a fusion of NUP98 and HOX or DDX10 genes may be more frequent in children than in patients of other age groups. The t(10;11)(p13- 14:q14- 21)is a rare but recurring translocation associated with acute lymphoblastic leukemia (ALL)and acute myeloid leukemia (AML). Recently, the CALM gene was cloned from the t(10;11)breakpoint of U937 and fused to AF10, a putative transcription factor, which had been identified as one of the fusion partners of the MLL gene. To define the involvement of these genes in primary leukemias and cell lines with t(10;11), we analysed the expression of fusion transcripts by reverse transcriptase- polymerase chain reaction (RT- PCR)in five patient samples, and three monocytic cell lines. The CALM- AF10 fusion transcript was detected in all samples. Our results suggest that the CALM- AF10 fusion gene is a constant feature and is involved in the pathogenesis of haematological malignancies with t(10;11)(p13- 14;q14- 21), showing various and often multilineage phenotypes.⁽¹⁴⁸⁾
　By a method combining SKY with DAPI banding, chromosome abnormalities in myelodysplastic syndromes were extensively analyzed in 20 specimens. This analysis revealed many chromosome translocations which were not detected by conventional karyotype analysis.⁽¹⁴⁹⁾ FISH analysis was applied and tested to establish diagnostic technique to detect t(8;21)using probes covering the AML1 gene and interphase cells.⁽¹⁵⁰⁾




8.RADIOBIOLOGY DIVISION



	Current research in Radiobiology Division focuses on the positional cloning of disease genes, especially of leukemia- related genes, and tumor suppressor genes. Functional analyses of several tumor- associated gene products including AML1 and the chimeric transcription factors AML1- MTG8 and FUS- ERG are also ongoing. Functional Analysis of Leukemia-associated Gene Products 　The FUS(TLS)- ERG chimeric protein associated with t(16;21)acute myeloid leukemia is structurally similar to the Ewing's sarcoma chimeric transcription factor EWS- ERG. Both FUS- ERG and EWS- ERG could induce anchorage- independent proliferation of NIH 3T3 cells. However, only FUS- ERG was able to inhibit the differentiation into neutrophhils of a mouse myeloid precursor cell line L- G and induce its granulocyte colony- stimulating factor- dependent growth. Analysis of several deletion mutants of FUS- ERG indicated that the N- terminal region of FUS contains two independent functional domains named TR1 and TR2 required for the NIH 3T3 and L- G transformation. Three cellular genes whose expression was altered by ectopic expression of FUS- ERG were identified, and they were found to be regulated in either a TR1- dependent or TR2- dependent manner. These results suggest that FUS- ERG may activate two independent oncogenic pathways during the leukemogenic process by simultaneously modulating the expression of two different groups of genes.⁽¹⁴⁴⁾ Genome Analysis and Genetic Alterations in Human Cancers 　Human chromosome 11q23.2 has been suspected to contain a tumor suppressor gene(s)whose deletion is associated with cancer of the lung and breast, and with neuroblastoma. To analyze the genomic structure and to isolate a candidate tumor suppressor gene from this region, we constructed a 2- Mb sequence- ready contig map ⁽¹⁴⁵⁾ using detailed physical maps.⁽¹⁴⁶⁾ The map comprises a contig of 24 overlapping P1, BAC, and PAC clones. To isolate gene fragments from the region, we performed direct cDNA library screening, exon trapping, EST mapping, and genomic sequencing using the P1, BAC, and PAC clones. Sequence analysis of 5 clones, which spans 23%of the region, and extensive gene scanning along the entire region revealed that the region is extraordinarily rare in genes, but we identified one ubiquitously expressed novel gene and one testis- specific gene fragment. The novel gene, which we call IGFS4 (immunoglobulin superfamily), is transcribed as a 1.6- or 4.4- kb RNA encoding a 442- amino- acid protein. It shares strong homology with mouse IGSF- B12 and the cell adhesion molecules NCAM1 and MCAM2 within their Ig- like C2- type domains. The IGSF4 gene, a novel gene that is located in the common loss of heterozygosity region, possesses a number of interesting features and may be a good candidate tumor suppressor gene.⁽¹⁴⁵⁾ 　In a survey of childhood therapy- related acute leukemia/myelodysplastic syndrome (t- AML/MDS)in Japan, 11p15 translocations were found in 5 (6%)of 81 children with t- AML/MDS. Also, t(11;17)(p15;q21), t(11;12)(p15;q13), t(7;11)(p15;p15), inv(11)(p15q22), and add (11)(p15)were found in one patient. Southern blotting and/or RT- PCR analyses revealed rearrangements of the NUP98 gene in tumor samples of all five patients.⁽¹⁴⁷⁾ This survey suggests that t- AML/MDS with a fusion of NUP98 and HOX or DDX10 genes may be more frequent in children than in patients of other age groups. The t(10;11)(p13- 14:q14- 21)is a rare but recurring translocation associated with acute lymphoblastic leukemia (ALL)and acute myeloid leukemia (AML). Recently, the CALM gene was cloned from the t(10;11)breakpoint of U937 and fused to AF10, a putative transcription factor, which had been identified as one of the fusion partners of the MLL gene. To define the involvement of these genes in primary leukemias and cell lines with t(10;11), we analysed the expression of fusion transcripts by reverse transcriptase- polymerase chain reaction (RT- PCR)in five patient samples, and three monocytic cell lines. The CALM- AF10 fusion transcript was detected in all samples. Our results suggest that the CALM- AF10 fusion gene is a constant feature and is involved in the pathogenesis of haematological malignancies with t(10;11)(p13- 14;q14- 21), showing various and often multilineage phenotypes.⁽¹⁴⁸⁾ 　By a method combining SKY with DAPI banding, chromosome abnormalities in myelodysplastic syndromes were extensively analyzed in 20 specimens. This analysis revealed many chromosome translocations which were not detected by conventional karyotype analysis.⁽¹⁴⁹⁾ FISH analysis was applied and tested to establish diagnostic technique to detect t(8;21)using probes covering the AML1 gene and interphase cells.⁽¹⁵⁰⁾