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

Regulation of Apoptosis and Autophagy During Anoxia in the Freshwater Crayfish, Faxonius virilis

The ability of an animal to survive prolonged periods of oxygen deprivation is a critical area of study, both in terms of its importance to better understanding the physiology of these incredible animals and to its potential applicability to medical fields. The freshwater crayfish, Faxonius virilis, is one such animal capable of resisting anoxia, but it remains understudied and much of the metabolic mechanisms underlying this anoxia tolerance remain largely unprofiled. This study examines the activity and regulation of apoptosis and autophagy in F. virilis in response to 20-h anoxia. Apoptosis signaling was assessed through pro- and anti-apoptosis targets, whereas autophagy was assessed via expression response of multiple autophagy proteins. An anoxia-triggered, tissue-specific result arose, potentially based on the importance of individual organ integrity through hypometabolism. Tail muscle, which showed increased expression profiles of all three target groups, contrasted with hepatopancreas, which appeared to not be susceptible to either apoptotic or autophagic signaling during anoxia. This is likely due to the importance of the hepatopancreas, given that apoptosis or autophagy of this organ at any significant level could be fatal to the organism. The data provides a comprehensive overview of the responses and integration of multiple stress-responsive signaling pathways in F. virilis that provide a novel contribution to our understanding of pro-survival mechanisms supporting invertebrate anoxia resistance.

Caffeic Acid Phenethyl Ester Effects: In Silico Study of its Osteoimmunological Mechanisms

Background:

Biological system complexity impedes the drug target identification by biological experiments. Thus drugs, rather than acting on target site only, can interact with the entire biological system. Study of this phenomenon, known as network pharmacology, provides grounds for biological target identification of new drugs or acts as a foundation for the discovery of new targets of present drugs. No publication is available on the interaction network of CAPE.

Aim:

This study was aimed at the investigation of the candidate targets and possible interactions of caffeic acid phenethyl ester (CAPE) involved in its osteoimmunological effects.

Methods:

This study encompasses the investigation of candidate targets and possible interactions of CAPE by analyzing through PASS Prediction and constructing a biological network of CAPE.

Results:

In response to input (CAPE), PASS Prediction generated a network of 1723 targets. While selecting the probability to be active (Pa) value greater than 0.7 brought forth only 27 targets for CAPE. Most of these targets predicted the therapeutic role of CAPE as an osteoimmunological agent. Apart from this, this network pharmacology also identified 10 potential anti-cancer targets for CAPE, out of which 7 targets have been used efficiently in developing potent osteoimmunological drugs.

Conclusion:

This study provides scientific prediction of the mechanisms involved in osteoimmunological effects of CAPE, presenting its promising use in the development of a natural therapeutic agent for the pharmaceutical industry. CAPE targets identified by web-based online databases and network pharmacology need additional in silico assessment such as docking and MD simulation studies and experimental verification to authenticate these results.

Risk of second cancer after chronic lymphocytic leukemia

Smoking is not considered a risk factor for chronic lymphocytic leukemia (CLL) yet increased lung cancer risk has been reported for these patients. Little data exist on the temporal variation in lung cancer risk after CLL, or its histological composition. We investigated the occurrence of second cancers in a large cohort of CLL patients with particular emphasis on lung cancer and its major subtypes. We followed all patients diagnosed with CLL in Denmark in the period 1943-2003 (n = 12,373) for the occurrence of second cancers. The relative risk was expressed as the standardized incidence ratio (SIR), i.e. the ratio of observed to expected number of cancers, based on incidence rates for the Danish population. During follow-up 1,105 cancers occurred among the CLL patients (SIR = 1.59 (95% CI 1.50-1.69)). SIR for all cancers combined remained elevated more than 10 years after CLL (SIR = 1.80 (1.56-2.08)). Lung cancer occurred in 141 patients (SIR = 1.61 (1.37-1.90)). The relative risk of lung cancer did not vary by gender, or time of follow-up, but was higher in younger (SIR(<60 years) = 2.22 (1.62-3.06)) than in older (SIR(70-79 years) = 1.21 (0.88-1.68)) age-groups. Elevated risks were observed for adenocarcinoma (SIR = 2.20 (1.57-3.08)) and squamous cell carcinoma (SIR = 1.52 (1.06-2.17)) of the lung. We speculate that shared genetic risk factors may explain the accumulation of lung and other cancers in CLL patients.

Splenic small B-cell lymphoma with IGH/BCL3 translocation

Isolated chromosomal translocations are important defining features of many non-Hodgkin lymphomas, especially of B-cell type. In contrast to some other translocations, the significance of IGH/BCL3 translocations is not well defined. Although often considered a feature of the ill-defined entity atypical chronic lymphocytic leukemia, very few cases are reported in which involvement of BCL3 and the precise B-cell neoplasm are both well documented. For this reason, we report a splenic-based CD5(-), CD10(-), CD43(-), CD23(-), CD103(-), FMC7(+), CD25(+) small B-cell lymphoma associated with epithelioid histiocyte clusters and a t(14;19)(q32;q13) representing an IGH/BCL3 translocation based on classical cytogenetic studies, chromosomal painting, and fluorescence in situ hybridization studies. The previously reported neoplasms with t(14;19)(q32;q13) or IGH/BCL3 translocations are also reviewed. The present case did not fall into any of the classic B-cell lymphoma categories and clearly did not represent chronic lymphocytic leukemia/small lymphocytic lymphoma. This case suggests that the IGH/BCL3 translocation may help to define a new clinicopathologic entity.

Interphase fluorescence in situ hybridization with an IGH probe is important in the evaluation of patients with a clinical diagnosis of chronic lymphocytic leukaemia

Translocations involving IGH are common in some lymphoid malignancies but are believed to be rare in chronic lymphocytic leukaemia (CLL). To study the clinical utility of fluorescence in situ hybridization (FISH) for IGH translocations, we reviewed 1032 patients with a presumptive diagnosis of CLL. Seventy-six (7%) patients had IGH translocations. Pathology and clinical data were available for the 24 patients evaluated at the Mayo Clinic. Ten (42%) patients had IGH/cyclin D1 fusion and were diagnosed with mantle cell lymphoma (MCL). The immunophenotype was typical of MCL in three of these patients and atypical for MCL in seven patients. One patient had biclonal disease with typical MCL and CLL with IGH/BCL-2. Eleven (46%) patients had IGH/BCL-2 fusion including the patient with biclonal disease. Two of these patients had leukaemic phase follicular lymphoma and nine patients had CLL. The median progression-free survival of patients with CLL and IGH/BCL-2 translocation was 20.6 months. The two patients with IGH/BCL-3 fusion (one of these also had IGH/BCL-11a) had rapid disease progression. The IGH partner gene was not identified in two patients. We conclude that use of an IGH probe in FISH analysis of monoclonal B-cell lymphocytosis improves diagnostic precision and could have prognostic value in patients with CLL.

BCL-1 rearrangement in acute lymphocytic leukemia and its clinical significance

BCL-1 rearrangement (BCL-1/IgH gene rearrangement) in acute lymphocytic leukemia and its clinical significance was investigated. In 38 patients with acute lymphocytic leukemia (ALL), the genomic DNA of mononuclear cells isolated from peripheral blood and bone marrow was amplified by using hemi-nested polymerase chain reaction (PCR) technique and the expression of cyclin D1 protein of mononuclear cells was detected by using immunohistochemical method. Ten patients with acute granulocytic leukemia, 2 with chronic granulocytic leukemia and 10 with normal bone marrow served as control group. The results showed that BCL-1 rearrangement was detectable in 3 of 38 ALL patients (7.9%) and cyclin D1 protein positive expression was detected in 4 ALL patients (10.5%). Three ALL patients with BCL-1 rearrangement were all B-cell leukemia (B-ALL) and accompanied by cyclin D1 protein expression. No BCL-1/IgH rearrangement or cyclin D1 protein expression was detected in 12 patients with granulocytic leukemia and 10 cases of normal bone marrow. Leukocyte counts in peripheral blood of B-ALL patients with BCL-1 rearrangement and (or) cyclin D1 protein expression were significantly increased and the patients had bad reaction to chemotherapy. It was concluded that: 1) BCL-1/IgH gene rearrangement were detected in acute B lymphocytic leukemia; 2) B-ALL patients with BCL-1 rearrangement and (or) cyclin D1 protein expression had poor prognosis.

The antiapoptotic effects of blood constituents in patients with chronic lymphocytic leukemia

OBJECTIVE

Clonal B-lymphocytes of chronic lymphocytic leukemia (B-CLL) are characterized by decreased sensitivity to programmed cell death and, therefore, they accumulate in vivo. However, these malignant cells die rapidly in vitro. In the current study we concentrated on the contribution of autologous serum (AS) and lymphocyte subsets to the survival of the malignant cells in vitro.

METHODS

Mononuclear cells from the peripheral blood of 26 CLL patients and 24 controls were incubated overnight in the presence or absence of AS and heat-inactivated AS (HI-AS) or fetal calf serum (FCS). Also, isolated B cells were incubated at different concentrations in the presence of AS and/or isolated T cells. The level of apoptosis of CD19+ cells was measured by flow cytometry.

RESULTS

Spontaneous apoptosis of unfractionated B-CLL cells incubated with AS, FCS or without serum was significantly lower than the rate of B-cell death in the control group, in similar culture conditions. AS had an antiapoptotic effect on unfractionated B-CLL cells when compared with FCS. The rate of apoptosis of B-CLL cells was directly associated with stage. HI of AS had a variable effect, which was related to the stage of the disease. High concentrations of B cells and the addition of autologous T cells reduced the rate of apoptosis when incubated without serum. The antiapoptotic effect of T cells was most prominent in progressive stages.

CONCLUSIONS

B-CLL cells exhibit decreased spontaneous apoptosis, which is partially prevented by humoral (AS) and cellular (T cells and B-CLL cells) factors. The equilibrium between apoptotic and antiapoptotic factors changes with disease progression.

Early gene activation in chronic leukemic B lymphocytes induced toward a plasma cell phenotype

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of lymphocytes that are arrested at an intermediate stage of B lymphocyte development. CLL B lymphocytes transform (mature) to a plasmacytic phenotype with loss of CD19 and CD20 and the appearance of cytoplasmic immunoglobulin when treated in vitro with phorbol esters. We have used array hybridization technology to describe gene expression patterns for untreated and tetradecanoyl phorbol acetate (TPA)-treated CLL B cells at 5, 10, and 20 min following initial TPA exposure. Three genes, early growth response factor 1 (EGR-1), dual specificity phosphatase 2, and CD69 (early T-cell activation antigen), showed a 2.0-fold or greater increase in mRNA transcription at four or more of six time points in two studies. Upregulation of expression of these genes was confirmed by real-time polymerase chain reaction in the TPA-treated cells of four CLL patients. A progressive increase in gene expression was observed during the 20-min time course for all three genes. In addition, protein expression of EGR-1 and CD69 was increased as measured by immunofluorescence cell analysis. Several genes (PKC, n-myc, jun D, and BCL-2) previously reported as overexpressed in CLL lymphocytes were overexpressed in these studies also, but were not altered by TPA treatment. Genes for proteins whose upregulation requires hours of TPA exposure (the 4F2hc component of the L-system amino acid transporter, prohibition, and hsp60) were assessed, and their later expression contrasted with the early expression of EGR-1, dual specificity phosphatase 2, and CD69. EGR-1 encodes a zinc-finger transcription factor that is induced by pokeweed mitogen and TPA and promotes B lymphocyte maturation. The dual specificity phosphatase 2 encodes an enzyme that reverses mitogen activated protein kinase cell activation by dephosphorylation. The CD69 protein is induced by TPA in thymocytes and is a type II transmembrane signaling molecule in hematopoietic cells. These findings suggest that the products of these three genes may be central to early steps in the TPA-induced evolution of CLL B cells to a plasmacytic phenotype.

Monosomy 21 in hematologic diseases

Monosomy 21 mosaicism as a sole cytogenetic abnormality is very uncommon, with 47 cases described in the literature. We identified five cases of low-level monosomy 21 mosaicism since 1998, none of which were confirmed by fluorescence in situ hybridization (FISH) analysis or follow-up cytogenetic studies. These five cases, and many of the previously reported cases, probably represent the random appearance of several monosomy 21 cells as artifacts of cell culture or microscope slide preparation. The most convincing reported cases of monosomy 21 mosaicism suggest a rare association of monosomy 21 with acute myelocytic leukemia and chronic lymphocytic leukemia. Future cases suggestive of monosomy 21 mosaicism should be confirmed by analysis of additional metaphase cells and by FISH analysis of interphase cells.

Bcl-2 rearrangement in patients with chronic hepatitis C associated with essential mixed cryoglobulinemia type II

Hepatitis C virus (HCV) infection is found in 80% to 90% of patients with essential mixed cryoglobulinemia (EMC) type II, which is associated with monoclonal IgMk produced by monoclonal B cells. It was investigated whether bcl-2 rearrangement is associated with the clonal B-cell proliferation of EMC induced by hepatitis C. The study groups were composed of 15 patients with HCV and EMC, 12 patients with HCV without EMC, and 7 patients with chronic liver disease (CLD) unrelated to HCV. Fluorescence in situ hybridization with probes was applied to JH and to bcl-2 to study whether JH/bcl-2 translocation was present in these patients. Thirteen of 15 (86%) of patients with HCV-related EMC had the JH/bcl-2 translocation, a significantly higher rate than in HCV patients without EMC (16%; P &lt; .001). Bcl-2 rearrangement was not detected in the patients with CLD not related to HCV. The JH/bcl2 translocation may constitute a pathogenetic link for the development of NHL in patients with HCV infection.

Bcl-2 rearrangement in patients with chronic hepatitis C associated with essential mixed cryoglobulinemia type II

Hepatitis C virus (HCV) infection is found in 80% to 90% of patients with essential mixed cryoglobulinemia (EMC) type II, which is associated with monoclonal IgMk produced by monoclonal B cells. It was investigated whether bcl-2 rearrangement is associated with the clonal B-cell proliferation of EMC induced by hepatitis C. The study groups were composed of 15 patients with HCV and EMC, 12 patients with HCV without EMC, and 7 patients with chronic liver disease (CLD) unrelated to HCV. Fluorescence in situ hybridization with probes was applied to JH and to bcl-2 to study whether JH/bcl-2 translocation was present in these patients. Thirteen of 15 (86%) of patients with HCV-related EMC had the JH/bcl-2 translocation, a significantly higher rate than in HCV patients without EMC (16%; P < .001). Bcl-2 rearrangement was not detected in the patients with CLD not related to HCV. The JH/bcl2 translocation may constitute a pathogenetic link for the development of NHL in patients with HCV infection.

Normal structure of NFKB2, C-REL and BCL-3 gene loci in lymphoproliferative and myeloproliferative disorders

NF-kappaB/rel transcription factors are crucial regulators of development, differentiation and apoptosis of both lymphoid and myeloid lineages. There is increasing evidence for an involvement of NF-kappaB/rel proteins in lymphomagenesis and resistance of lymphoid tumors to the induction of apoptosis. Structural alterations of the NF-kappaB/rel genes NFkappaB2, c-rel and bcl-3 have been shown to result in increased NF-kappaB/rel activity. Because we observed strong constitutive NF-kappaB/rel binding activity in chronic lymphocytic leukemia of the B-cell type (B-CLL) which may contribute to resistance against cytotoxic drugs we studied the genomic organisation of NFkappaB2, c-rel and bcl-3 gene loci in a panel of lymphoproliferative disorders (n=81) with an emphasis on B-CLL (n=47). The method of genomic Southern blotting using cDNAs of the respective genes was used. In spite of the role of NF-kappaB/rel in myeloid maturation there is no data available as to the occurrence of NF-kappaB/rel rearrangements in chronic myeloproliferative syndromes (cMPS). For this reason we included a small panel of cMPS patients (n=16). Southern Blotting revealed a germline configuration of NFkappaB2, c-rel and bcl-3 loci in all NHL and cMPS patients examined. Our results demonstrate that structural alterations of NFkappaB2, c-rel and bcl-3 genes at the Southern Blotting level are rare events that do not contribute to lymphoid or myeloid transformation in the majority of NHL or cMPS patients.

B-cell lymphoma-associated hemophagocytic syndrome

B-cell lymphoma-associated hemophagocytic syndrome (B-LAHS) is extremely rare in Western countries but has recently been increasingly reported in Asian countries, especially Japan. Here, we reviewed 25 previously reported Japanese cases of B-LAHS and summarized its clinicopathologic features and therapeutic outcome. The median age of onset was 63 years old with initial presentation of fever, hepatomegaly, and splenomegaly without associated lymphadenopathy. Laboratory findings showed increased levels of lactate dehydrogenase, C-reactive protein, ferritin and soluble interleukin-2 receptor. Histopathologically, hemophagocytosis was often seen in the bone marrow and spleen. Various percentages of lymphoma cells were seen in the bone marrow, positive for CD19, CD20 and surface immunoglobulin. and some were also positive for CD5. Cytogenetic analysis showed a complex structural abnormality including chromosome 14q32, 19q13 and deletion of the terminal part of 8p21. Some patients had histological features of intravascular lymphomatosis (IVL). The prognosis was poor with a median survival period of 9 months. We treated five patients using autologous peripheral blood stem cell transplantation (PBSCT), and four are still in complete remission nine to 24 months after PBSCT, suggesting that high-dose chemotherapy followed by PBSCT might improve the survival rate.

Morphological and immunophenotypic features of chronic lymphocytic leukemia

In this review, we summarize the morphological features and immunophenotypic profile of chronic lymphocytic leukemia (CLL) cells, discuss the value of these investigations as front line diagnostic tests, and emphasize their correlation with the clinical features, disease progression, molecular genetics and pathogenesis of CLL. In CLL, the morphology of the circulating cells is characteristic and typical in the majority of cases. However, 15% of patients, either at diagnosis or during the course of the disease, show atypical morphology reflected by either (1) an increased (> 10%) number of circulating prolymphocytes, designated CLL/PL, or (2) an increased (> 15%) number of circulating lymphoplasmacytic and cleaved cells, designated 'atypical' CLL. There is strong evidence of a close association between atypical morphology (CLL/PL) and atypical (CLL) and clinical features, e.g. disease progression, advanced stage and survival, molecular genetics, particularly trisomy 12, but also the rare cases with t(11;14) or t(14;19), p53 abnormalities, unmutated immunoglobulin (Ig) VH genes and origin of the cell (naive, pregerminal center cell). CLL cells have a distinct immunological repertoire different from that of other lymphoproliferative disorders. The typical CLL phenotype is CD5+, CD23+, FMC7-, weak expression of surface Ig (sIg) and weak or absent expression of membrane CD22 and CD79b. The latter marker identifies an extracellular epitope of the B-cell receptor (BCR) beta chain and its weak or absent expression in CLL may derive from the expression of a truncated form. This, together with the low expression of CD22, might explain the abnormal signal transduction of CLL cells similar to that of anergic B lymphocytes. Because no single marker is specific for CLL, a composite phenotype considering this set of 5 or 6 markers compounded into a scoring system helps to distinguish CLL from the other B-cell malignancies. Immunophenotypic analysis has also been shown to be useful for minimal residual disease detection and adds valuable prognostic information because the expression of certain markers, such as FMC7 or CD38, seems to be associated with a poor outcome. In addition, CLL cells express a variety of Bcl-2 family proteins with a profile that favors inhibition of apoptosis which, together with the interaction with microenvironmental (e.g. stromal) cells and the release of cytokines, explains the long life span and subsequent accumulation of CLL cells in various organs. Despite controversies relating to the expression of adhesion molecules (selectins and integrins) in CLL cells, it appears that some of these molecules do play a role in the pathogenesis, biology and clinical patterns of the disease. In conclusion, morphology and immunophenotype are the two essential investigations, which must be carried out in all cases of CLL. Both provide relevant information in terms of diagnosis, course of the disease, prognosis and pathogenesis.

B-cell lymphoma associated with haemophagocytic syndrome: a clinical, immunological and cytogenetic study

B-cell lymphoma associated with haemophagocytic syndrome (HPS) is extremely rare in Western countries but has recently been increasingly reported in Asian countries. We describe seven patients with B-cell lymphoma associated with HPS, six males and one female, age range 41-82 years (median 63 years). All patients had fever and splenomegaly, and six of the seven patients had hepatomegaly with no associated lymphadenopathy. The bone marrow showed haemophagocytosis and an infiltration of lymphoma cells. All patients showed increased levels of lactate dehydrogenase, C-reactive protein, ferritin and soluble interleukin-2 receptor. Lymphoma cells were positive for CD19. CD20 and surface immunoglobulin in all patients examined, and positive for CD5 in four of seven patients. Cytogenetic analyses of bone marrow cells showed a complex structural abnormality including chromosome 14q32 in two patients, 19q13 in three patients and deletion of the terminal part of 8p21 in six patients. The prognosis was poor; only two of the seven patients have survived in complete remission with a median survival of 11 months. These data suggested that B-cell lymphoma associated with HPS might constitute a distinct biological and clinical disease entity. Abnormality of chromosome 19q13 and loss of 8p21 might be involved in the pathogenesis of this disease.

The concept of typical and atypical chronic lymphocytic leukaemia

Subdivision of CLL into typical and atypical subtypes, as proposed by the FAB group in 1989, is not yet widely accepted and its clinical significance is still debated. In recent years, however, a strong correlation was found between atypical morphology trisomy 12 and an aberrant immunophenotype. In the first part of this review we discuss current concepts and generally accepted data on morphology, immunophenotype, genetic abnormalities, clinical features and prognostic factors in CLL. Subsequently, based on our own series and other recently published data, we analyse the validity and clinical impact of classifying CLL into typical and atypical entities and demonstrate that they may represent two closely related but different entities.

Translocation (11;14)(q13;q32) and overexpression of cyclin D1 protein in a CD23-positive low-grade B-cell neoplasm

We describe a case of low-grade B-cell neoplasm with features overlapping between B-chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). The patient presented with a 10-year history of stable CLL without any treatment. The peripheral-blood picture was consistent with atypical mixed CLL (French-American-British criteria), whereas the lymph-node histology was more consistent with MCL. Neoplastic cells were strongly positive for surface immunoglobulin M, kappa, CD5, CD20, CD23, and cyclin D1. Expression of CD11c was weak. Translocation (11;14) and der(10)t(10;?)(p11;?) were the primary cytogenetic changes observed in both peripheral blood (47%) and lymph node (7%). Trisomy 12 was absent. Deletion 6q21 and rearrangements involving 1p/q, consistently associated with progression in lymphomas, also were noted in the peripheral blood but were nonclonal. The present case and similar cases with features overlapping between CLL and MCL most likely represent hybrids. In cases with features of typical CLL, t(11;14) is probably associated with gradual progression and may precede clinical and histologic transformation.

Gene transfer of CD40-ligand induces autologous immune recognition of chronic lymphocytic leukemia B cells

CD40-CD40-ligand (CD154) interactions play a critical role in immune activation. Using replication defective adenovirus encoding mouse CD154 (Ad-CD154), we modified human chronic lymphocytic leukemia B cells to express a functional ligand for CD40. This not only induces expression of immune accessory molecules on the infected cell, but also allows it to trans-activate noninfected bystander leukemia B cells. Also, factors that impair the antigen-presenting capacity of leukemia B cells are downmodulated. Ad-CD154- infected leukemia cells are highly effective stimulators in mixed lymphocyte reactions and can induce generation of cytotoxic T lymphocytes specific for autologous nonmodified leukemia cells. As such, Ad-CD154 can induce a host antileukemia response that may have therapeutic potential.

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.

Genetic alterations in leukemias and lymphomas: impressive progress and continuing complexity

Cytogenetic clues and molecular techniques have led to the identification of a very large number of genes involved in the pathogenesis of human leukemias and lymphomas, most of them previously unknown and many of them "activated" by chromosomal translocations. The oncogenic effects of most of these genes are narrowly restricted to a particular cell lineage or stage of differentiation. Research is continuing on the mechanisms by which various types of cancer genes participate in the development of hemic neoplasms, and on how this information can be effectively utilized to develop new clinical approaches to the control of these disorders.

Genes and chromosomes in chronic B-cell leukemia

Cytogenetic analysis of patients with chronic B-cell leukemia (B-CLL) indicates that 50% have chromosome abnormalities, while fluorescence in situ hybridization (FISH) and molecular techniques reveal an even higher incidence. Trisomy 12 and deletions or translocation of chromosome 13q14 are the most common abnormalities, but in neither case has the gene or genes involved in the abnormalities been identified. Combined FISH and immunophenotyping studies suggest that both abnormalities are secondary events in B-CLL. Other recurring chromosome abnormalities include 6q-, 11q- and 12p-, but the genes involved in these abnormalities have not been identified. Involvement of the BCL1, BCL2, and BCL3 genes has been reported, but the numbers are low and the cases tend to be atypical. Trisomy 12 in association with complex karyotypic abnormalities is associated with a poor prognosis, and FISH studies show a strong correlation between trisomy 12, atypical morphology, and advanced disease. Ten to 15% of patients have mutations of p53 which is associated with advanced disease, resistance to treatment, and poor survival.