Cytogenetic and molecular changes in chronic B-cell leukemia

CDK1 is up-regulated by temozolomide in an NF-κB dependent manner in glioblastoma

The alkylating agent, temozolomide (TMZ), is the most commonly used chemotherapeutic for the treatment of glioblastoma (GBM). The anti-glioma effect of TMZ involves a complex response that includes G2-M cell cycle arrest and cyclin-dependent kinase 1 (CDK1) activation. While CDK1 phosphorylation is a well-described consequence of TMZ treatment, we find that TMZ also robustly induces CDK1 expression. Analysis of this pathway demonstrates that CDK1 is regulated by NF-κB via a putative κB-site in its proximal promoter. CDK1 was induced in a manner dependent on mature p50 and the atypical inhibitor κB protein, BCL-3. Treatment with TMZ induced binding of NF-κB to the κB-site as assessed by gel shift analysis and chromatin immunoprecipitation. Examination of a CDK1 promoter-reporter demonstrated the functional relevance of the κB-site and underlined the requirement of p50 and BCL-3 for activation. Targeted knockdown of CDK1 or chemical inhibition with the selective CDK1 inhibitor, RO-3306, potentiated the cytotoxic effect of TMZ. These results identify CDK1 as an NF-κB target gene regulated by p50 and BCL-3 and suggest that targeting CDK1 may be a strategy to improve the efficacy of TMZ against GBM.

Decoy Receptor DcR1 Is Induced in a p50/Bcl3-Dependent Manner and Attenuates the Efficacy of Temozolomide

Temozolomide is used widely to treat malignant glioma, but the overall response to this agent is generally poor. Resistance to DNA-damaging drugs such as temozolomide has been related to the induction of antiapoptotic proteins. Specifically, the transcription factor NF-κB has been suggested to participate in promoting the survival of cells exposed to chemotherapy. To identify factors that modulate cytotoxicity in the setting of DNA damage, we used an unbiased strategy to examine the NF-κB-dependent expression profile induced by temozolomide. By this route, we defined the decoy receptor DcR1 as a temozolomide response gene induced by a mechanism relying upon p50/NF-κB1. A conserved NF-κB-binding sequence (κB-site) was identified in the proximal promoter and was demonstrated to be required for DcR1 induction by temozolomide. Loss-of-function and gain-of-function studies reveal that the atypical IκB protein, Bcl3, is also required for induction of DcR1 by temozolomide. Mechanistically, DcR1 attenuates temozolomide efficacy by blunting activation of the Fas receptor pathway in p53(+/+) glioma cells. Intracranial xenograft studies show that DcR1 depletion in glioma cells enhances the efficacy of temozolomide. Taken together, our results show how DcR1 upregulation mediates temozolomide resistance and provide a rationale for DcR1 targeting as a strategy to sensitize gliomas to this widely used chemotherapy.

Activation of oxidative stress-regulated Bcl-3 suppresses CTCF in corneal epithelial cells

Epigenetic factor CTCF (CCCTC binding factor) plays important roles in genetic controls of the cell fate. Previous studies found in corneal epithelial cells that CTCF is regulated by epidermal growth factor (EGF) through activation of NF-κB p65/p50. It also found that CTCF is suppressed in ultraviolet (UV) stress-induced corneal epithelial cells. However, it is still unknown how UV stress down-regulates CTCF affecting the cell fate. In the present study, we report that regulation of CTCF by extracellular stress signals is dependent upon activations of an oxidative stress-regulated protein Bcl-3. We found that activated Bcl-3 was able to bind to the κB sites identified in the CTCF promoter region. Bcl-3 was activated by UV irradiation to interact with NF-κB p50 by forming a Bcl-3/p50 heterodimer complex. The Bcl-3/p50 complex suppressed CTCF promoter activity to down-regulate CTCF transcription. Unlike the effect of EGF, UV stress-induced Bcl-3 activation suppressed CTCF activity without involving the IκBα and p65 pathway. Thus, results of the study reveal a novel mechanism for regulatory control of CTCF in UV stress-induced human corneal epithelial cells, which requires activation and formation of Bcl-3/p50 complex through a noncanonical NF-κB pathway.

Depletion of the oncoprotein Bcl-3 induces centrosome amplification and aneuploidy in cancer cells

Bcl-3 is an atypical member of the inhibitor of NF-kappa B family of proteins since it can function as a coactivator of transcription. Although this oncogene was described in leukemia, it is overexpressed in a number of solid tumors as well. The oncogenic potential of Bcl-3 has been associated with its capacity to increase proliferation by means of activating the cyclin D1 promoter and to its antiapoptotic role mediated by the inhibiton of p53 activity. In the course of dissecting these properties, we found that depleting Bcl-3 protein using shRNAs induce a decrease of proliferation and clonogenic survival associated with the induction of multinucleation and increased ploidy. These effects were associated with a DNA damage response, a delay in G2/M checkpoint and the induction of centrosome amplification

Bcl-3, a multifaceted modulator of NF-kappaB-mediated gene transcription

The transcription factor, NF-kappaB (nuclear factor-kappaB) and associated regulatory factors make up a multi-component signaling pathway that regulates a wide range of biological processes, including cell survival, proliferation, differentiation, stress response, and death, as well as immunity and inflammation. Aberrant NF-kappaB pathway activity is known to be associated with a host of diseases, including immune deficiencies, inflammatory disorders, and cancer. Recent advances in our understanding of the inner workings of the NF-kappaB pathway have led to the development of new therapeutic strategies for the treatment of these diseases. In this review, we focus on the regulation of the NF-kappaB pathway by Bcl-3 (B cell leukemia-3), a nuclear member of the IkappaB (inhibitor of NF-kappaB) family. Both the regulation and the function of Bcl-3 will be discussed.

Transgenic Bcl-3 slows T cell proliferation

Immunological adjuvants, such as bacterial LPS, increase the mRNA levels of the IkB-related NF-κB transcriptional transactivator, Bcl-3, in activated T cells. Adjuvants also increase the life expectancy of activated T cells, as does over-expression of Bcl-3, suggesting that Bcl-3 is part of the pathway whereby adjuvants affect T cell lifespans. However, previous reports, confirmed here, show that adjuvants also increase the life expectancies of Bcl-3-deficient T cells, making Bcl-3’s role and effects in adjuvant-induced survival uncertain. To investigate the functions of Bcl-3 further, here we confirm the adjuvant-induced expression of Bcl-3 mRNA and show Bcl-3 induction at the protein level. Bcl-3 was expressed in mice via a transgene driven by the human CD2 promoter. Like other protective events, over-expression of Bcl-3 slows T cell activation very early in T cell responses to antigen, both in vitro and in vivo. This property was intrinsic to the T cells over-expressing the Bcl-3 and did not require Bcl-3 expression by other cells such as antigen-presenting cells.

Expression of nuclear factor-kappaB family proteins in hepatocellular carcinomas

PURPOSE

Nuclear factor-kappaB (NF-kappaB) has been shown to be abnormally activated in some human hepatocellular carcinomas (HCCs), but most studies of NF-kappaB in patient samples have focused on the p65 subunit. Recent information has implicated IkappaB family members (e.g. Bcl-3) as possible mediators of NF-kappaB activation. Therefore, we examined the expression of all NF-kappaB family members and downstream targets in HCC.

STUDY DESIGN

Archived HCCs from 30 patients were evaluated by immunohistochemistry for NF-kappaB family proteins, Bcl-3 and targets of NF-kappaB/IkappaB function. Results were validated by Western blotting in frozen paired HCC and adjacent normal tissue in a subset of cases.

RESULTS

NF-kappaB p50 and p52 subunits were frequently localized to tumor cell nuclei (40 and 48%), whereas p65 positivity was infrequent. Bcl-3 was overexpressed in 90% of tumor cell nuclei compared with 26% of adjacent non-neoplastic liver (p < 0.001).

CONCLUSIONS

Aberrant Bcl-3 nuclear expression occurs in the vast majority of HCCs compared with adjacent normal or cirrhotic liver tissue. Bcl-3 is known to interact with NF-kappaB p50 and p52 homodimers, and our study demonstrates very frequent nuclear colocalization of Bcl-3 and p50/p52, suggesting that the Bcl-3/p50 or Bcl-3/p52 interactions are important in HCC pathogenesis.

Use of chromosome painting for detecting stable chromosome aberrations induced by melphalan in mice

Chromosomal aberrations are a measure of genomic instability, which is known to play a key role in the initiation and promotion of carcinogenesis. Stable reciprocal translocations are of particular importance since they are often involved in neoplastic transformation and tumor cell clonal evolution. In this study, chromosome painting analysis was used to test for stable aberrations induced in the bone marrow of C57BL/6J and FVB mice exposed for 4 weeks to 2 or 4 mg/kg of melphalan (MLP), a chemotherapeutic agent with carcinogenic potential. To compare the chemical-induced damage in different tissues, chromosome aberrations were also analyzed by chromosome painting in the spleen of C57BL/6J mice. At the 2 mg/kg dose, MLP induced comparable levels of chromosome-type aberrations in bone marrow cells of both mouse strains and in splenocytes of C57BL/6J mice. At 4 mg/kg, no further increase in aberrations was detected in bone marrow, while a dose-effect relationship was found in spleen cells. This different response may result from a negative selection against highly damaged bone marrow cells during mitotic proliferation. The results indicate that chromosome painting is a useful tool for detecting stable chromosome aberrations in somatic cells exposed to MLP and possibly to other genotoxic chemical carcinogens.

A translocation breakpoint at chromosome band 12q13 associated with B-cell chronic lymphocytic leukemia

Low-grade B-cell lymphoproliferative disorders are frequently associated with an extra copy of chromosome 12. This well-documented acquired anomaly is one of the most specific numerical chromosome alterations to occur in human hematological malignancies. We have cytogenetically characterized bone marrow and peripheral blood cells from a patient with B-cell chronic lymphocytic leukemia (CLL) having a unique acquired translocation involving chromosomes 6 and 12, t(6;12) (p21.3;q13), which implicates band 12q13 as the site of the gene(s) important in this lymphoproliferative B-cell disorder. Aneuploidy, in the form of trisomy of chromosome 12, is not a requirement for neoplastic transformation in B-cell CLL, but gene rearrangement (present case) or nondisjunctional acquisition of additional copies of defective genes on chromosome 12 at band q13 may be involved in the genesis or progression of this disorder.

Specific numerical chromosomal aberrations induced by adriamycin

Fluorescence in situ hybridization with 7, 17, X, and Y chromosome-specific DNA probe was used to investigate the ability of Adriamycin (AM) to induce aneuploidy in interphase human lymphocytes. The reliability of the probes was tested by hybridization to metaphases and interphase nuclei of untreated normal lymphocytes. Two signals were scored in over 87% of the analyzed nuclei with chromosome 7 and 17 probes, whereas one signal was recorded in over 86% of the nuclei with chromosomes X and Y. The same conditions and probe concentrations were used for hybridizing the four probes to interphase nuclei of AM-treated and untreated lymphocytes, cultured from healthy individuals and cancer patients. AM was found to induce significant increases of trisomy 7 and 17 in lymphocytes cultured from healthy individuals and cancer patients, where the interphase nuclei showed three spots in over 70% and 72% of the cells, respectively. Only 6% of interphase nuclei of untreated cells cultured from healthy individuals and cancer patients showed three spots. No significant increase in X or Y aneuploidy was induced by exposure to AM.

Spontaneous breakage and fragile site expression in chronic lymphocytic leukemia

It has been suggested that genetic predisposition to cancer might be related to spontaneous chromosome instability or to fragile site expression. Therefore, spontaneous breakage and fragile sites were analyzed in nine untreated chronic lymphocytic leukemia (CLL) patients to determine their relation to cancer rearrangements. Five cases presented spontaneous gaps and breaks with a random distribution of breakpoints. In cultures treated with fluorodeoxyuridine or aphidicolin, 29 specific bands could be defined as fragile sites. A significant clustering of these sites was found with known common fragile sites (c-fra) and cancer breakpoints described in the literature. Most of these cancer breakpoints were involved in structural abnormalities associated with CLL (p < 0.00001). These data suggest that the expression of specific fragile sites might be related to structural chromosomal aberrations in CLL.

Monoallelic p53 deletion in chronic lymphocytic leukemia detected by interphase cytogenetics

Chromosomal aberrations can be detected in 50% of patients with chronic lymphocytic leukemia (CLL). A role for tumor suppressor genes in the genesis of lymphoid tumors has been reported. In B-CLL, p53 gene mutations were found in 10-15% of the patients. We used fluorescence in situ hybridization (FISH) to detect p53 deletion in B-CLL. We also correlated the cytogenetic findings with the clinical course. In situ hybridization to interphase nuclei showed monallelic p53 deletion in 6 of 23 patients (26%). The percentage of cells with one p53 signal ranged from 12 to 100. A statistically significant correlation between p53 deletion and progression of CLL was demonstrated. We conclude that FISH is a sensitive and reliable method to detect deletion of specific genes (i.e., p53) in CLL. The finding of p53 deletion is associated with disease progression.

Cytogenetic studies in seventy-six cases of B-chronic lymphoproliferative disorders

The results of cytogenetic studies are reported in 76 patients with B-chronic lymphoproliferative disorders (B-CLPD): 60 patients with chronic lymphocytic leukemia (CLL), six with follicular lymphoma in leukemic phase (FLLP), five with splenic B-cell lymphoma with villous lymphocytes (SLVL), two with chronic prolymphocytic leukemia (CPL), two with hairy cell leukemia (HCL), and one with plasma cell leukemia (PCL). PHA (phytohemagglutinin), PWM (pokeweed mitogen), LPS (lipopolysaccharide from Escherichia Coli), TPA (phorbol 12-myristate acetate), IL6 (interleukin 6), and DxS (dextran sulfate) were used as mitogens. Mitoses were obtained in 75 cases. Clonal aberrations could be demonstrated in 34 cases (44%). In CLL, classical type, chromosomes 6, 11, and 13 were more frequently involved, whereas trisomy 12 was frequently found in CLL mixed-cell type, in FLLP, and CPL. In SLVL the deletion del(7)(q32) is noteworthy and miscellaneous chromosome abnormalities in the remaining patients were observed. Regarding the efficiency of mitogens, PHA turned to be the most effective in obtaining metaphases and in detecting clonal chromosomal aberrations.

The detection and evaluation of aneugenic chemicals

Although aneuploidy makes a significant contribution to both somatic and inherited disease the mechanisms by which environmental chemicals may induce numerical chromosome aberrations are only poorly defined. The European Union Project was aimed to further our understanding of those chemical interactions with the components of the mitotic and meiotic cell division cycle which may lead to aneuploidy and to characterise the parameters such as cellular metabolism which may influence the activity of aneugenic chemicals. C-mitosis can be induced by the highly lipophilic polychlorinated biphenyl and the completion of mitosis and cleavage can be modified by agents which deplete cellular levels of reduced glutathione. Modifications of the fidelity of chromosome segregation were produced by inhibiting the functioning of topoisomerase II during chromatid separation. In contrast, the modification of centromere integrity resulted in chromosome breakage as opposed to disturbance of segregation. Modifiers of tubulin assembly and centriolar functioning in somatic cells such as acrylamide, vinblastine and diazepam reproduced their activity in rodent bone marrow and male germ cells. The analysis of chromosome malsegregation in Aspergillus nidulans by a structurally related series of halogenated hydrocarbons was used to develop a QSAR model which had high predictive value for the results of fungal tests for previously untested related chemicals. Metabolic studies of potential aneugens in genetically engineered human lymphoblastoid cells demonstrated the detoxification of the aneugenic activity of chloral hydrate and the activation of 2,3-dichlorobutane, 1,1,2-trichloroethane and trichloroethylene by Phase I biotransforming enzymes. Cell transformation studies in Syrian hamster dermal cultures using a panel of 22 reference and or potential aneugens indicated that 15 of the 22 produced positive results following single exposures. Five of the aneugens which were negative following single exposures produced positive results where cultures were continuously exposed for up to 6 weeks to low concentrations following a single non-transforming exposure to the mutagen dimethyl sulphate. The transformation studies indicate that a significant proportion of chemical aneugens are potential complete carcinogens and/or co-carcinogens. To optimise the enumeration of chromosomes following exposure to potential chemical aneugens whole chromosome paints and centromere specific probes suitable for use in fluorescence in situ hybridisation (FISH) were developed for the rat, mouse and Chinese hamster and selected human probes evaluated for their suitability for routine use. Molecular chromosome probes were used to develop protocols for enumerating chromosomes in metaphase cells and centromeres and micronuclei in interphase cells. The analysis of segregation of specific centromeres in binucleate cells following cytochalasin B treatment was shown to be a potentially valuable system for characterising non-disjunction following chemical exposure. Whole chromosome paints and centromere specific probes were used to demonstrate the presence of dose-response thresholds following treatment with a reference panel of spindle inhibiting chemicals. These data indicate that the FISH technology is suitable for evaluating the relative hazards of low-dose exposures to aneugenic chemicals.

BCL3 rearrangement and t(14;19)(q32;q13) in lymphoproliferative disorders

Translocation t(14;19)(q32;q13) is a rare but recurrent abnormality in chronic lymphocytic leukemia and small cell lymphoma. It has been associated with rearrangements of the BCL3 gene, which is located at the breakpoint on chromosome 19 and is juxtaposed to the immunoglobulin heavy chain locus on chromosome 14 as a result of the translocation. This results in transcriptional up-regulation of the BCL3 gene, which encodes a transcription coactivator, an I-kappa B protein, probably contributing to disease progression. We found, among 4,487 cytogenetic analyses of lymphoproliferative disorders, six cases with a t(14;19)(q32;q13), five of which showed the classical t(14;19)(q32;q13) and one of which showed a three-way translocation t(7;19;14)(q21;q13;q32). The 14;19 translocation never occurred as a single abnormality; additional aberrations included trisomy 12 and several structural abnormalities. The cytogenetic examination was supplemented by molecular analysis using available probes for the BCL3 locus (p alpha 1.4P and p alpha 5B) in 1,150 of the 4,487 patients. Rearrangements of BCL3 could be detected in five cases, all of which had the classical t(14;19). In the case with t(7;19;14), the suspected BCL3 involvement could only be confirmed using long-range restriction mapping, indicating that, with the usually available BCL3 probes, rearrangements of this locus may be missed.

The BCL-1, BCL-2, and BCL-3 oncogenes are involved in chronic lymphocytic leukemia. Detection by fluorescence in situ hybridization

The putative oncogenes BCL-1, BCL-2, and BCL-3 are commonly rearranged by translocations to the immunoglobulin genes in B-cell malignancies. However, Southern blotting rarely detected their involvement in chronic lymphocytic leukemia (CLL). This discrepancy could stem from some unique features of the oncogenesis of CLL or be due to shortcomings of Southern blotting. We have therefore evaluated the role of fluorescence in situ hybridization (FISH) in the detection of these oncogenes in CLL. Twenty consecutive CLL patients were studied by FISH for the detection of BCL-1, BCL-2, or BCL-3 rearrangement and for the presence of trisomy 12. Selected patients were also evaluated by classical cytogenetic techniques and by Southern blot analysis. Juxtaposition of JH and BCL-1 was demonstrated in 10 (50%), BCL-2 in three (15%), and BCL-3 in four (20%) of the patients. Trisomy 12 was detected by FISH in 11 (55%) patients. The coexistence of trisomy 12 and translocation of the BCL-1 oncogene was common. Three of the patients had chromosomal aberrations compatible with those detected by FISH. In contrast, in none of the five patients selected by their positive FISH findings was a rearrangement demonstrated by Southern blotting. We conclude that FISH is a sensitive method for the detection of oncogene involvement in CLL. Mainly BCL-1, but also BCL-2 and BCL-3, are commonly translocated to the immunoglobulin heavy chain locus on chromosome 14. These translocations are often associated with trisomy 12. These findings indicate that the BCL oncogenes are commonly involved in CLL and lend support to the multi-hit theory of cancer development.

Hodgkin's disease developing after spontaneous remission of chronic lymphocytic leukemia

We present a 71-year-old patient with chronic lymphocytic leukemia diagnosed 27 years ago. Initially, the disease was staged as Rai II and the patient suffered from secondary immunoglobulin deficiency. Nevertheless, no treatment was necessary at that time. Because of disease progression a single course of chemotherapy was given in 1984. During the following year there was a constant decline of the WBC, accompanied by normalization of the immunoglobulins; both have remained stable ever since that time. However, there was still residual bone marrow infiltration, indicating persisting CLL. In 1993 cervical lymphadenopathy occurred with acute onset. A diagnostic lymphadenectomy revealed Hodgkin's disease of the nodular-sclerosing subtype. The patient was staged as II-III according to the Ann Arbor Classification and underwent radiation therapy. Cytogenetic examination of the bone marrow revealed a normal karyotype with an inversion of chromosome 9. This case demonstrates the rate coincidence of two lymphoproliferative disorders in the same patient. The clinical course and the immunologic findings of this patient are presented, together with a review of the literature.

The spectrum of chronic lymphoproliferative disorders in Chinese people. An analysis of 64 cases

BACKGROUND

Chronic lymphoproliferative disorders are considered rare in Oriental patients and are thought to constitute only 2% of all leukemias in these patients, compared to 20-30% in Western patients. We conducted a retrospective analysis of Chinese patients with chronic lymphoproliferative disorders to define the frequency and spectrum of these disorders.

METHODS

A consecutive series of Chinese patients with leukemia and lymphoproliferative disorders seen at two regional hospitals in Hong Kong were analyzed retrospectively. The diagnosis of chronic lymphoproliferative disorders was based on morphologic and immunologic criteria proposed by the French-American-British Cooperative Study Group.

RESULTS

Sixty-four Chinese patients with chronic lymphoproliferative disorders were identified, and these patients constituted 19% of a total of 342 cases of leukemia diagnosed in 3 years. Chronic lymphocytic leukemia was the most common form, occurring at a frequency of 12.5% of all leukemias. The clinicopathologic features of these patients were similar to those of Western patients, except that Chinese patients tended to present with more advanced (Rai's Stages III and IV; Binet's Stage C) and bulky (splenomegaly > 9 cm) disease, and expressed lambda light chain about six times more frequently. Other chronic lymphoproliferative disorders identified in this study included prolymphocytic leukemia, mantle zone lymphoma, hairy cell leukemia, splenic lymphoma with villous lymphocytes, large granular lymphocyte leukemia, and Sezary syndrome. The authors did not identify any case of human T-cell lymphotropic virus-I-related lymphoproliferative disorders within the study period.

CONCLUSION

In addition to providing the frequencies of various chronic lymphoproliferative disorders in southern Chinese people, this study also showed that these disorders no longer should be considered rare in this population. Inherent biologic differences between lymphoproliferative disorders in Chinese and Western patients also may exist.

Detection of bcl rearrangements in B-CLL by fluorescence in situ hybridization

Data concerning oncogene activation in CLL are very limited. When studied by Southern blot, rearrangements of bcl-1, bcl-2, and bcl-3 have been only infrequently reported. We evaluated the role of fluorescence in situ hybridization (FISH) in the detection of gene rearrangements in two CLL patients. We used multiple DNA probes, including those of chromosome 12, immunoglobulin heavy and light chains, and the oncogenes bcl-1, bcl-2, and bcl-3. Additionally, routine cytogenetic study was performed. In one patient, trisomy 12 and bcl-2 translocation were demonstrated by both methods, while trisomy 12 and bcl-1 translocation were seen in the second patient, who had a normal karyotype. Larger studies should evaluate the role of FISH in the detection of oncogene involvement in CLL and compare it with other molecular methods.

Trisomy 12 in chronic lymphocytic leukemia. An interphase cytogenetic study by fluorescence in situ hybridization

B-cell chronic lymphocytic leukemia (CLL) is a rare disorder in the Chinese population. We evaluated the use of fluorescence in situ hybridization (FISH) with a chromosome 12-specific probe in the detection of trisomy 12 in interphase cell of 19 Chinese CLL patients. FISH successfully detected trisomy 12 in two cases, one of which had normal conventional cytogenetic findings, giving an incidence of 10%. The low incidence of trisomy 12 in our CLL patients may also reflect a biologic difference of this rare disorder in our population, compared to that of the West.

In situ hybridization: a simple and sensitive method for detection of trisomy 12 in chronic lymphocytic leukemia

Chromosome aberrations are detected in only 50% of patients with chronic lymphocytic leukemia (CLL), owing usually to the low mitotic rate exhibited by the neoplastic lymphocytes. Fluorescence in situ hybridization (FISH) is a simple method for identifying numerical abnormalities of the target chromosome in interphase nuclei. Therefore, we used the FISH procedure with chromosome 12-specific a-satellite probe to evaluate 19 patients with CLL. Trisomy 12 was detected in interphase cells of 12 patients (63%). Cytogenetic analysis, performed in nine patients, yielded trisomy 12 in four (44%). FISH detected three patients with trisomy 12 in whom conventional cytogenetic method yielded a normal karyotype. FISH is a simple, reliable, and sensitive method for detection of trisomy 12 in patients with CLL.

A new chromosomal anomaly associated with mature B-cell chronic lymphoproliferative disorders: del(7)(q32)

Among 63 patients with chronic lymphoproliferative disorders (CLPD) studied cytogenetically in our laboratory, four showed a del(7)(q32); in two it was the sole cytogenetic anomaly and in two it was part of a complex karyotype. We suggest that despite the rarity of this anomaly, it could be related to CLPD.

Frequent clonal abnormalities of chromosome band 13q14 in B-cell chronic lymphocytic leukemia: multiple clones, subclones, and nonclonal alterations in 82 midwestern patients

We performed cytogenetic analyses of peripheral blood lymphocytes from 82 Midwestern B-cell chronic lymphocytic leukemia (B-CLL) patients. The cells were cultured with mitogens for 3-4 days. At least 15 metaphase cells were analyzed in 79 (96%) cases. Fifty (63%) of the 79 patients had clonal chromosomal alterations. Structural modifications of the long arm of chromosome 13 at or near band 13q14 were the most frequent abnormalities, identified in 23 (46%) of the patients with clonal abnormalities. In several patients, the abnormality involving band 13q14 was the sole chromosomal alteration. There was a high incidence of complex karyotypes. Nine patients had multiple subclones that appeared to result from clonal evolution; seven patients had cytogenetically unrelated clones; three patients had both subclones and cytogenetically unrelated clones. Nonclonal abnormalities were also prominent. Our study confirms the high incidence of clonal abnormalities involving chromosome arm 13q and documents the clustering of abnormalities at band 13q14 in B-CLL. The evidence for clonal evolution and the presence of multiple unrelated clones in these patients suggest that B-CLL may not be a karyotypically stable disease.

New chromosomal abnormality. t(1;19;?) in a case of B-chronic lymphocytic leukemia

Cytogenetic analysis was performed on peripheral blood cells stimulated with interleukin 6 (IL-6), lipopolysaccharide from Escherichia coli (LPS), phytohemagglutinin (PHA), pokeweed mitogen (PWM) and tetradecanoyl-phorbol-acetate (TPA), in a patient with B-chronic lymphocytic leukemia, showing a t(1;19;?) translocation as the sole abnormality. To our knowledge, this translocation has not been described before in any human neoplasia. In this case, the poor response to therapy (survival time 4 months) suggested that t(1;19;?) could be related to an aggressive course of the disease.

Chromosome analyses in chronic lymphocytic leukemia and related B-cell neoplasms

Chromosome analyses were performed by routine G-banding in 29 patients with B-cell chronic lymphocytic leukemia (B-CLL), six with immunocytoma (IC), three with centroblastic-centrocytic (cb-cc) lymphoma, and one with hairy cell leukemia (HCL). Ages of the patients were between 46 and 81 years (mean, 63 years). 12-O-tetradecanoyl-phorbol-13-acetate (TPA) was used as a mitogen to stimulate leukemic B-cells in 72-hour cultures. Twenty-one patients had one or more chromosomal abnormalities; and in 13 patients, they were clonal; 18 patients had a normal karyotype. Seven patients had trisomy 12 (three B-CLL, two IC, two cb-cc lymphoma); two (B-CLL) had it as the sole abnormality. One patient with B-CLL had trisomy 18 as the sole abnormality, and one with IC had trisomy 18 in combination with trisomy 19. One patient with B-CLL had t(1;6)(p36;p21) as a clonal structural abnormality. A t(11;14)(q13;q32) was consistently observed in one patient with cb-cc lymphoma together with inv(1) (p22p36), der(4)t(4;?)(p16;?), del(6)(q13) and other variable changes. One patient with morphologically atypical B-CLL had t(1;11)(p36;q13) together with der(X)t(X;?)(q26;?), der(3)t(3;?)(q29;?), der(8)t(4;8)(q12;q24.1) and additional variable changes. Both patients with these complex karyotypes were in an advanced stage of disease (Binet stage C) and died within 3-6 months after chromosome analysis.

Translocation (14;19) in acute biphenotypic leukemia

Translocation (14;19)(q32;q13.1) is an acquired chromosomal rearrangement that has been associated with chronic lymphocytic leukemia of B-cell phenotype frequently progressing to lymphoma. Molecular analysis suggests that the translocation involves the immunoglobulin heavy chain gene on chromosome 14 and the BCL3 oncogene on chromosome 19. We present the first case of t(14;19) in a patient with acute leukemia. Correlation of detailed cytogenetic and molecular genetic studies, cell surface marker analysis, cytochemistry, and electron microscopy indicated that the leukemic cells were biophenotypic, with characteristics consistent with both myeloid and B-lineage lymphoid differentiation.

c-myc and K-ras-2 oncogenes in B-cell chronic lymphocytic leukemia with del(12)(p13)

Molecular and cytogenetic analyses were performed on chronic B-lymphocytic cell leukemia (CLL) from a 57-year-old male patient with del(12)(p13) anomaly. The deletion did not remove the K-ras-2 gene. However, c-myc gene amplification correlated with high-level expression, suggesting the involvement of this gene in the induction of neoplasia in this patient.