[Clinical evaluation of cefozopran for infections associated with hematological malignancies]

Cefozopran (CZOP) was used as an initial antibacterial therapy for infections in patients with hematological malignancies. CZOP was given at a daily dose of 4 g by drip intravenously to patients who were febrile over 38 degrees C and were suspected as having bacterial infections. As underlying diseases, 8 patients had acute lymphoblastic leukemia (ALL), 9 acute myeloblastic leukemia (AML), 2 aplastic anemia (AA), 2 adult T cell leukemia/lymphoma (ATLL), 28 non Hodgkin lymphoma (NHL), and 2 multiple myeloma (MM). Bacterial infections diagnosed were sepsis in 7 patients, suspected sepsis in 32, bronchitis in 6, pneumonia in 5 and acute peritonitis in 1. Clinical responses among 51 evaluable cases were excellent in 14, good in 15, fair in 3, poor in 19 and the overall response rate was 57%. The overall response rates for AML, ALL, AA, ATLL, NHL and MM were 56%, 63%, 100%, 50%, 50%, and 100%, respectively. Those for sepsis, suspected sepsis, bronchitis, pneumonia and acute peritonitis were 14%, 63%, 100%, 40%, and 0%, respectively. This therapy was effective in 53% (9/17) of patients whose granulocyte count remained below 500/microliter throughout the course of CZOP therapy. Six bacterial and one fungal strains were isolated from blood and sputum of six patients including five sepsis cases; two bacteria were eradicated and bacterial change was observed in one case. As side adverse effects, 10 patients had liver dysfunction, 1 anemia, 2 proteinemia, 1 indirect bilirubinemia, 2 thrombocytopenia, and 1 eosinophilia. We tried to establish a scoring system for the severities of patients with their infections, underlying diseases, treatments for the underlying disease, and granulocyte counts in order to evaluate the efficacy of CZOP more precisely. This scoring system was consisted of three grades; severe, moderate, and mild. CZOP was effective on mild and moderate grades. These results indicate that the initial antibacterial therapy by CZOP is useful for the treatment of mild and moderate grade infections complicated with hematological malignancies.

A variant Burkitt-type translocation (8;22)(q24;q11) in multiple myeloma. Report of a new case and review of the literature

We report here a new case of multiple myeloma (IgG, kappa, stage IIIA) with a variant Burkitt-type translocation (8;22)(q24;q11). Bone marrow plasma cells were morphologically immature with fine nuclear chromatin and nucleoli. Chromosome analysis showed complex aberrations; that is, 53,XX, der(1)add(1)(p11)dup(1)(q12q32),+3,+5,t(8;22)(q24;q11),+9,add(10)( p13), +11,+15,add(19)(q13),+21. Fluorescence in situ hybridization analysis with the yeast artificial chromosome (YAC) clone I2 containing the C-MYC gene at 8q24 and the chromosome-22-specific DNA library pBS22 revealed that 12 was located on the der(8)t(8;22). A fusion signal derived from I2 and the YAC clone B99E1 containing the BCR gene at 22q11 was also observed on the der(8)t(8;22). Our results indicate that the breakpoint at 8q24 in this patient was located far downstream of the C-MYC gene. This breakpoint site is similar to Burkitt lymphoma with t(8;22)(q24;q11). A review of eight cases in the literature and the present case of multiple myeloma with t(8;22)(q24;q11) showed that most of them were of advanced stage and had an immature phenotype. It is suggested that the C-MYC gene may be activated by t(8;22)(q24;q11) and implicated in disease progression in multiple myeloma.

Significance of chromosomal alterations and mutations of the N-RAS and TP53 genes in relation to leukemogenesis of acute myeloid leukemia

We examined chromosomes and mutations of the N-RAS and TP53 genes in 73 patients with acute myeloid leukemia (AML). Twenty-six patients showed a reciprocal chromosomal translocation or an inversion, and 34 patients showed only unbalanced aberrations. Balanced aberrations were predominantly detected in the AML patients who did not have myelodysplasia, preceding myelodysplastic syndrome, and a history of chemotherapy or radiation therapy. In contrast, unbalanced aberrations were more frequently seen in the patients with AML with trilineage myelodysplasia, AML transformed from MDS, and therapy-related AML. Twenty-two mutations of the N-RAS and TP53 genes were detected, and these mutations were frequently associated with unbalanced chromosomal aberrations. Furthermore, the spectrum of mutations was suggestive of an exposure to alkylating chemicals.

A novel mature B-cell line (DOBIL-6) producing both parathyroid hormone-related protein and interleukin-6 from a myeloma patient presenting with hypercalcaemia

A novel human EBV-negative B-cell line, designated DOBIL-6, was established from a patient with non-secretary myeloma. The DOBIL-6 cell has cytoplasmic gamma protein and expresses CD19, 20, 38, 45RO, VLA-4 and PCA-1 antigens, but lacks CD10, 45RA and VLA5 antigens. Chromosome analysis showed that DOBIL-6 cells had many complex structural abnormalities, including t(11;4) (q13;q32), which were consistent with that of the fresh tumour cells. Interestingly, abundant interleukin-6 (IL-6) and parathyroid hormone-related protein (PTHrP) accumulated in the culture supernatant of DOBIL-6 cells. Hypercalcaemia and splenomegaly associated with plasma cell proliferations which resulted in the expansion of the light zones in the follicles were observed in DOBIL-6 transplanted nude mice. RT-PCR analysis detected mRNA for PTHrP, and IL-6 as well as its receptor (GP80) in DOBIL-6 cells. Treatment of the DOBIL-6 cells with neutralizing anti-IL-6 antibody inhibited their growth in a dose-dependent manner, whereas the addition of exogenous IL-6 stimulated it in serum-depleted conditions. These findings suggest that both IL-6 and PTHrP are produced in DOBIL-6 cells, and that IL-6 promotes its growth by an autocrine mechanism. Since IL-6 is known to stimulate not only the growth of B-cell neoplasms but also osteoclastic bone resorption by cooperating with PTHrP, this simultaneous production of IL-6 and PTHrP might be synergistically linked and play a role in the development of hypercalcaemia of the patient. The DOBIL-6 cell is a useful tool to clarify the mechanism of hypercalcaemia associated with mature B-cell neoplasms.

The gene for human protein Z is localized to chromosome 13 at band q34 and is coded by eight regular exons and one alternative exon

Human protein Z is a vitamin K-dependent plasma glycoprotein, deficiency of which leads to a mild bleeding tendency. Protein Z appears to assist hemostasis by binding thrombin and promoting its association with phospholipid vesicles. In this study, to characterize the gene for protein Z, its organization and structure were determined by a combination of PCR amplification of leukocyte DNA and isolation of phage clones from a human genomic library. The gene spanned about 14 kb and consisted of 9 exons including one alternative exon. It was of note that the gene organization was essentially identical to that of other vitamin K-dependent proteins, such as factors VII, IX, and X and protein C. The nucleotides in introns at exon/intron boundaries for eight regular exons were the consensus GT-AG sequences. In contrast, the sequence at an optional exon/intron junction was found to be GC rather than GT. The extra exon inserts a unique peptide consisting of 22 amino acids in the prepro-leader sequence. A similar situation was previously observed in factor VII, but not in other vitamin K-dependent plasma proteins. We also assigned the gene for protein Z to chromosome 13 by PCR amplification of genomic DNAs from human/hamster cell hybrids. Fluorescence in situ hybridization, employing a genomic clone coding for human protein Z, further localized the gene to band q34, where the genes of three other vitamin K-dependent proteins are clustered. These genes may have evolved via duplication of an ancestral gene at this locus.

Cytochrome b in human complex II (succinate-ubiquinone oxidoreductase): cDNA cloning of the components in liver mitochondria and chromosome assignment of the genes for the large (SDHC) and small (SDHD) subunits to 1q21 and 11q23

Complex II (succinate-ubiquinone oxidoreductase) is an important enzyme complex in both the tricarboxylic acid cycle and the aerobic respiratory chains of mitochondria in eukaryotic cells and prokaryotic organisms. In this study, the amino acid sequences of the large (cybL) and small (cybS) subunits of cytochrome b in human liver complex II were deduced from cDNAs isolated by homology probing with mixed primers for the polymerase chain reaction. The mature cybL and cybS contain 140 and 103 amino acids, respectively, and show little similarity to the amino acid sequences of the subunits from other species in contrast to the highly conserved features of the flavoprotein (Fp) subunit and iron-sulfur protein (Ip) subunit. From hydrophobicity analysis, both cybL and cybS appear to have three transmembrane segments, indicating their role as membrane-anchors for the enzyme complex. Histidine residues, which are possible heme axial ligands in cytochrome b of complex II, were found in the second transmembrane segment of each subunit. The genes for cybL (SDHC) and cybS (SDHD) were mapped to chromosome 1q21 and 11q23, respectively by fluorescent in situ hybridization (FISH).

[Clinical study on the inhibitory effect of a 5-HT3 antagonist, granisetron, for nausea and vomiting induced by chemotherapy (CHOP, VEPA, high-dose ETP) for non-Hodgkin's lymphoma]

The antiemetic effect of granisetron on nausea and vomiting induced by cancer chemotherapy (CHOP, VEPA, VEPA-B, massive dose of ETP) was studied in fifty patients with non-Hodgkin's lymphoma. There was almost no difference in the inhibitory effect by regimen, with the rates of perfect inhibition of nausea and vomiting standing at 55.6% to 60%. Nausea and vomiting was perfectly controlled in 60% of 35 patients receiving CHOP therapy. As a part of this study, a comparison was made of perfect inhibitory effect on nausea and vomiting by potency of chemotherapy under the potency scale of 750 mg/m2 of CPA as 1, revealing no significant difference in the rates of complete inhibition as 71.4% for a drug potency of less than 0.8 vs 52.4% for 0.8 or above (p = 0.26). However, it was clear that the higher the dose of chemotherapy, the lower the rate of complete inhibition. The results confirmed the high efficacy and safety of granisetron in the treatment of nausea and vomiting induced by cancer chemotherapy.

A new complex translocation (15;20;17)(q22;p13;q21) in acute promyelocytic leukemia

We describe here a 39-year-old male with acute promyelocytic leukemia (APL) carrying a new complex translocation (15;20;17). A chromosomal analysis of the bone marrow cells showed 46, XY, t(15;20;17)(q22;p13;q21). Fluorescence in situ hybridization (FISH) analysis using plasmid DNA libraries of chromosomes 15, 17, and 20 revealed three derivative chromosomes, der(15)t(15;17), der(17)t(17;20), and der(20)t(15;20). Fluorescence in situ hybridization with cosmid DNA probes flanking the breakpoints of t(15;17) did not show the retinoic acid receptor alpha (RAR alpha)/PML fusion signal usually generated on the der(17)t(15;17). However, rearrangement of the RAR alpha gene and expression of the PML/RAR alpha chimeric transcript were identified by Southern blot and reverse-transcriptase polymerase chain reaction (RT-PCR) analyses, respectively. Our results confirmed that the PML/RAR alpha gene on the der(15)t(15;17), not the RAR alpha/PML gene, must be essential to leukemogenesis in APL. Furthermore, considering another reported case with a 20p13 aberration, it is possible that 20p13 is a nonrandom breakpoint in APL with a complex translocation.

Establishment of a new human myeloma cell line, KMS-18, having t(4;14)(p16.3;q32.3) derived from a case phenotypically transformed from Ig A-lambda to BJP-lambda, and associated with hyperammonemia

A new human myeloma cell line, KMS-18, was established from a 58-year-old male with multiple myeloma associated with hyperammonemia. The original leukemic cells and established KMS-18 cells possessed several of the same chromosomal abnormalities, including add(1)(q32), add(10) (q24) and add(17)(p11). In addition, the KMS-18 cells showed novel t(4;14)(p16.3;q32.3) masked translocation which was determined by the FISH method. Moreover, we compared the ammonia production in culture medium of the KMS-18 cell line with that of non-myeloma hematological malignant cell lines and a hepatocellular carcinoma cell line. KMS-18 produced higher levels of ammonia in medium than the other cell lines examined. This new cell line may prove helpful in analyzing the role and biological mechanisms of the t(4;14)(p16.3;q32.3) translocation in myeloma and also in investigating hyperammonemia in cases with myeloma.

Multiple polypoid lesions of primary mucosa-associated lymphoid-tissue lymphoma of colon

AIMS

This study was focused on unusual cases of mucosa-associated lymphoid tissue (MALT) lymphoma presenting with multiple polypoid lesions of the colon and rectum with a special reference to the differential diagnosis of mantle cell lymphoma.

METHODS AND RESULTS

The lesions of these five cases grossly showed a segmental distribution of nodular protrusions in three patients and of innumerable small polyps in two. These patterns of involvement simulated those of multiple lymphomatous polyposis, known as the gastrointestinal presentation of mantle cell lymphoma (MCL), and caused a differential diagnostic problem between MALT lymphoma and MCL, which have different prognostic and therapeutic implications. Their histological features are almost indistinguishable from each other, especially in the small biopsy specimens via endoscope. The most important procedure for their differentiation is cyclin D1 immunohistochemistry and its negative reaction provides strong indication of MALT lymphoma. Of interest, one case showed a rare karyotypic abnormality of t(11;18)(q21;q21), which has been reported specifically in MALT lymphoma.

CONCLUSIONS

This study has indicated that the multiple polypoid lesions of the colon occur not only in MCL, but also in MALT lymphoma, making differential diagnosis between the two entities necessary, and cyclin D1 immunohistochemistry is indispensable for distinguishing between them.

Trisomy 12 and t(14;18) in B-cell chronic lymphocytic leukemia

We report a case of B-cell chronic lymphocytic leukemia (B-CLL) in which trisomy 12 and t(14;18)(q32;q21) were simultaneously detected in the same leukemic clone. Southern blot analysis showed that the BCL2/IgJH rearrangement occurred at the major breakpoint region in the hot spot of the BCL2 gene. Double color fluorescence in situ hybridization analysis using multiple probes indicated that clonal B-cell with t(14;18) represented a subpopulation of the total leukemic cells and that trisomy 12 followed t(14;18) as the cytogenetic aberration in the development of B-CLL. Our findings suggests that both the t(14;18) and the trisomy are secondary chromosomal changes in the leukemogenesis of B-CLL.

Adenoviral E1A-associated protein p300 is involved in acute myeloid leukemia with t(11;22)(q23;q13)

p300, which was originally cloned as a nuclear binding target of the adenovirus E1A oncoprotein, forms a family with cyclic-AMP response element binding protein (CREB)-binding protein (CBP). p300/CBP are considered to be transcriptional coactivators that connect the basal transcriptional machinery to various DNA-binding transcriptional factors. p300/CBP are implicated in both cell differentiation and regulation of cell-cycle. We identify here that the p300 gene is fused to the MLL gene and that in-frame MLL-p300 fusion protein is generated in acute myeloid leukemia (AML) with t(11; 22)(q23; q13). These findings suggest that the basis for the leukemogenesis of t(11; 22)-AML is the inability of p300 to regulate cell-cycle and cell differentiation after fusion with MLL.

Interphase detection of BCL6/IgH fusion gene in non-Hodgkin lymphoma by fluorescence in situ hybridization

We characterized a t(3;14)(q27;q32) translocation in nine patients with B-cell, non-Hodgkin lymphoma (B-NHL) by fluorescence in situ hybridization (FISH). Fluorescence in situ hybridization with immunoglobulin heavy chain (IgH) and BCL6 gene probes detected t(3;14) rapidly and accurately, including complex t(3;14) in three patients; one with t(3;12;8;14)(q27;p13;q24.1;q32) and two with t(3;?;14)(q27;?;q32). Among these nine patients, seven escaped from cytogenetic detection by our G-banding analysis. Double-color FISH with IgH (Y6) and BCL6 (cosB5-1) showed fusion of BCL6 and IgH genes on der(3)t(3;14) in all nine patients, suggesting that der(3) may play a critical role in the development of lymphoma carrying complex as well as standard t(3;14) translocations. BCL6/IgH fusion gene was also demonstrated in interphase nuclei at a frequency of 23% to 91.5% over the cut-off value in control studies (9.0 +/- 2.76%). The breakpoints assessed by FISH with two cosmid clones containing BCL6 probes, cosB5-1 and cosB5-2, were within the cluster region in seven patients including one with complex type, but were not evaluated in two patients with t(3;?;14), because of the loss of partner chromosome. Using double-color FISH with these two BCL6-specific probes, none of an additional 32 patients in whom mitotic spreads were available showed 3q27 translocations. Fluorescence in situ hybridization with IgH and BCL6 gene probes is a rapid and sensitive method to detect t(3;14) in routine cytogenetic studies.

Chimerism analysis on mononuclear cells in the CSF after allogeneic bone marrow transplantation

To evaluate the chimeric status of mononuclear cells in the CSF after allogeneic BMT, cells were analyzed by FISH using satellite DNA probes for human X and Y chromosomes. CSF cells were obtained from five pediatric ALL patients who received BMT from sex-mismatched donors. All patients received TBI-containing conditioning regimens. We found that CSF cells showed complete donor type in 19-97 days after BMT, when complete donor type hematopoiesis was observed. The rapid entry of the donor leukocytes into the brain may exert beneficial effects to eradicate the residual CNS leukemic cells and prevent a CNS relapse in ALL patients after BMT.

Tandem duplications of the FLT3 receptor gene are associated with leukemic transformation of myelodysplasia

We recently reported an internal tandem duplication of the human flt3 receptor gene (FLT3) as a somatic mutation in 17% of acute myelogenous leukemia (AML). The present study revealed the duplication at the juxtamembrane and the first tyrosine kinase domains of FLT3 in seven of 92 (8%) patients with myelodysplastic syndrome (MDS) and AML with trilineage myelodysplasia (AML/TMDS), the diseases which may represent neoplastic changes of pluripotent stem cells. A tandem duplication of exon 11 of FLT3 was harbored by two of 58 (3%) patients with MDS and five of 34 (15%) with overt leukemia, including MDS-derived leukemia, AML/TMDS and therapy-related leukemia. Although the duplicated regions varied within exon 11 in each case, they occurred in-frame, and altered mRNA expressions were demonstrated by reverse-transcription polymerase chain reaction. Two cases of MDS with a FLT3 duplication transformed to overt leukemia within a few months. Longitudinal analyses in two other patients with leukemia revealed that the duplication was a late genetic event during the disease course; one of whom showed two independent duplications of FLT3 at the terminal therapy-resistant phase. Of seven patients with the FLT3 duplication, six had abnormal karyotypes, and four harbored a point mutation of the N-RAS and/or TP53 genes. Patients with FLT3 mutations have poor prognoses. This study uncovered the fact that the accumulation of genetic events, including FLT3 duplication, correlates with leukemic transformation from antecedent myelodysplasia and with subsequent disease progression.

Alterations of p53 and Rb genes in a novel human GM-CSF-dependent myeloid cell line (OHN-GM) established from therapy-related leukaemia

A novel GM-CSF-dependent myeloid cell line, OHN-GM, was established from a patient who developed acute myelogenous leukaemia (AML) as a consequence of myelodysplastic syndrome (MDS). As the patient had previously received cytotoxic chemotherapy for Hodgkin's disease, the MDS and AML were probably related to such therapy. Sequential karyotypic analysis established a del(5q) as the initial cytogenetic abnormality. Additional alterations, including t(10;13)(q24;q14), had developed subsequently during disease progression. Southern blot analysis of OHN-GM cells suggested deletion of one allele of the IRF-1 gene, although no aberrant transcripts were detected. Fluorescence in situ hybridization analysis revealed the deletion of the Rb gene due to the t(10;13)(q24;q14) translocation, and Western blot analysis demonstrated the absence of Rb protein in OHN-GM cells. Finally, the OHN-GM cells exhibited two missense point mutations in highly conserved regions of the p53 gene. These observations suggest that a multistep process, involving alterations of Rb and p53 genes, may have contributed to the patient's disease development and progression. To our knowledge, OHN-GM is the first cell line derived from a therapy-related AML. These cells may aid the investigation of leukaemogenesis as well as the biology of secondary leukaemia.

Establishment of a novel human B-cell line (OZ) with t(14;18)(q32;q21) and aberrant p53 expression was associated with the homozygous deletions of p15INK4B and p16INK4A genes

The novel human pre-B cell line OZ was established from a patient with an aggressive form of non-Hodgkin's lymphoma. Karyotypic analysis of both the primary tumour and OZ cells revealed several marker chromosomes, including the t(14;18)(q32;q21) translocation, which involves the Bcl-2 gene, and alterations on chromosome 17p. Southern blot analysis found identical rearrangements in the 5' region of Bcl-2 gene in the primary tumour and OZ cells. Homozygous deletions of the p15INK4B and p16INK4A genes, however, were present only in OZ cells. Western blot analysis detected aberrant small molecular-weight p53 proteins in both cell types. In addition, OZ cells no longer expressed the CD20 antigen. These findings suggest that Bcl-2 gene rearrangement and aberrant p53 expression resulted in the original B-cell tumour. A subsequent transforming event involving the p15INK4B and p16INK4A genes may have generated more immature cells with a growth advantage during in vitro culture. The genetic alterations involving p53, p15INK4B, and p16INK4A may be implicated in the aggressive form of t(14;18)(q32;q21)-bearing tumours and their poor prognosis.

Detection of 14q32.33 translocation and t(11;14) in interphase nuclei of chronic B-cell leukemia/lymphomas by in situ hybridization

Abnormalities of chromosome 14 involving band q32.33 are among the most commonly observed cytogenetic alterations in B-cell malignancies. To assess the incidence and pathogenetic implications of 14q32.33 translocation in chronic B-cell leukemia/lymphomas, we performed fluorescence in situ hybridization (FISH) analysis with variable region (V(H)) and gamma constant region (Cgamma) gene probes in 37 patients with these disorders. Chromosome 14q32.33 translocation was detected in 2 of 18 patients with chronic lymphocytic leukemia (CLL), 1 of 2 with CLL of mixed cell types (CLL/PL), 1 of 2 with pro-lymphocytic leukemia (PLL), 5 of 6 with leukemic mantle-cell lymphoma (MCL), 2 of 7 with splenic B-cell leukemia/lymphoma of possible marginal zone origin (SBLL) and 2 with leukemic follicular lymphoma (FL). To further characterize 14q32.33 translocations in these patients, we developed a new procedure using double-color FISH with PRAD1, BCL2, V(H) and Cgamma gene probes. Chromosome t(11;14) was detected in 1 patient with CLL/PL, 1 with PLL and 5 with MCL. Chromosome t(14;18) was detected in 2 patients with FL. In a PLL patient with t(11;14), the cosmid CPP29 containing the PRAD1 gene and its 5'-flanking region split and co-localized with both Cgamma and V(H) gene probes, thus spanning the breakpoint. In CLL and SBLL patients, donor chromosomes were other than chromosomes 2, 11, 18 and 19, suggesting the involvement of a novel oncogene(s) in the pathogenesis of these diseases. Interphase FISH rapidly detected 14q32.33 translocation, t(11;14) and t(14;18) in B-cell malignancies with low mitotic activity at the single-cell level, facilitating the correlation of the molecular features of these translocations with clinical characteristics.

The Ig heavy chain gene is frequently involved in chromosomal translocations in multiple myeloma and plasma cell leukemia as detected by in situ hybridization

Chromosome rearrangement of 14q32.33 has recurrently occurred with variable partner sites, including 11q13.3, 8q24.1, 18q21.3, and 6p21.1 in multiple myeloma (MM). To assess the actual incidence of 14q32.33 translocation and to elucidate its implication in the pathogenesis of MM, we studied 42 patients with MM, plasma cell leukemia, or plasmacytoma and 5 with monoclonal gammopathy with undetermined significance (MGUS) by G-banding and molecular cytogenetic methods. Using double-color fluorescence in situ hybridization (DCFISH) with 2 Ig heavy chain (IgH) gene probes, a yeast artificial chromosome (YAC) clone containing variable region, and a phage clone containing gamma constant region, 14q32.33 translocation was detected as split signals of the IgH gene in 31 patients with plasma cell malignancies and 3 with MGUS. In contrast, of 40 patients who were assessed by G-banding, 3 (7.5%) showed the 14q+ chromosome. DCFISH detected a split of the IgH gene on interphase nuclei in 34 (73.9%) of 46 patients analyzed, whereas on metaphase spreads, it was in 22 (51.2%) of 43 patients analyzed. Interphase DCFISH was particularly useful to detect 14q32.33 translocation in 17 (65.4%) of 26 patients with normal karyotypes. Donor sites were identified in 11 of 22 patients demonstrated as carrying 14q32.33 translocation by metaphase FISH. Chromosome t(11;14)(q13.3; q32.33) was detected in 5 patients, t(8;14)(q24.1;q32.33) in 2, t(14;18)(q32.33;q21.3) in 2, and t(7;14)(q32.1;q32.33) in 1. A complex 14q32.33 translocation involving 3q and 16q24 was detected in 1 patient. Myeloma cells with t(7;14) showed myelomonocytoid surface antigen. Because rearrangements of 14q32.33 were closely associated with translocation of proto-oncogenes into the IgH gene, our findings indicate that 14q32.33 translocation with various partner chromosomes is a critical event in the pathogenesis of MM and MGUS.

Detection of 14q32.33 translocation and t(11;14) in interphase nuclei of chronic B-cell leukemia/lymphomas by in situ hybridization

Abnormalities of chromosome 14 involving band q32.33 are among the most commonly observed cytogenetic alterations in B-cell malignancies. To assess the incidence and pathogenetic implications of 14q32.33 translocation in chronic B-cell leukemia/lymphomas, we performed fluorescence in situ hybridization (FISH) analysis with variable region (V(H)) and gamma constant region (Cgamma) gene probes in 37 patients with these disorders. Chromosome 14q32.33 translocation was detected in 2 of 18 patients with chronic lymphocytic leukemia (CLL), 1 of 2 with CLL of mixed cell types (CLL/PL), 1 of 2 with pro-lymphocytic leukemia (PLL), 5 of 6 with leukemic mantle-cell lymphoma (MCL), 2 of 7 with splenic B-cell leukemia/lymphoma of possible marginal zone origin (SBLL) and 2 with leukemic follicular lymphoma (FL). To further characterize 14q32.33 translocations in these patients, we developed a new procedure using double-color FISH with PRAD1, BCL2, V(H) and Cgamma gene probes. Chromosome t(11;14) was detected in 1 patient with CLL/PL, 1 with PLL and 5 with MCL. Chromosome t(14;18) was detected in 2 patients with FL. In a PLL patient with t(11;14), the cosmid CPP29 containing the PRAD1 gene and its 5'-flanking region split and co-localized with both Cgamma and V(H) gene probes, thus spanning the breakpoint. In CLL and SBLL patients, donor chromosomes were other than chromosomes 2, 11, 18 and 19, suggesting the involvement of a novel oncogene(s) in the pathogenesis of these diseases. Interphase FISH rapidly detected 14q32.33 translocation, t(11;14) and t(14;18) in B-cell malignancies with low mitotic activity at the single-cell level, facilitating the correlation of the molecular features of these translocations with clinical characteristics.

Cloning of a human homolog of the yeast OGG1 gene that is involved in the repair of oxidative DNA damage

We report the cloning of a human homolog of the yeast OGGC1 gene, which encodes a DNA glycosylase that excises an oxidatively damaged form of guanine, 8-hydroxyguanine (also known as 7,8-dihydro-8-oxoguanine). Since the deduced amino acid sequence (68 amino acids) of a human expressed sequence tag, N55394, matched a short stretch of yeast OGG1 protein with greater than 40% amino acid identity, a full length cDNA clone was isolated from a HeLa cell cDNA library with the N55394 clone as a probe. The cDNA clone encodes a predicted protein of 345 amino acids which is homologous to yeast OGG1 protein throughout the entire polypeptide sequence and shares 38% amino acid identity with yeast OGG1 protein. Moreover, we found that both a human homolog and yeast OGG1 protein possess two distinct DNA binding motifs, a helix-hairpin-helix (HhH) motif and a C2H2 zinc finger like motif, and a domain homologous to human and E. coli MutY proteins. Expression of a human homolog suppressed spontaneous mutagenesis of an E. coli (mutM mutY) mutant as in the case of yeast OGG1 protein. The gene was ubiquitously expressed in a variety of human organs and mapped to chromosome 3p26.2. These results strongly suggest that the gene isolated here is a human counterpart of the yeast OGGI gene and is involved in the repair of oxidative DNA damage in human cells.