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At least 703 records · Page 39Linked to original sources
PubMed2004

Isolated bone marrow involvement in diffuse large B cell lymphoma: a report of three cases with review of morphological, immunophenotypic and cytogenetic findings.

Diffuse large B cell lymphoma (DLBL) comprises a heterogenous entity characterized by the presence of large cells, exhibiting a mature B cell phenotype. The high proliferation rate and aggressive disease remain a therapeutic challenge, but the apparent biological diversity permits a risk-stratification model for prognostic grouping through the International Prognostic Index (IPI). Empirical to this approach is the consideration of cytogenetic data, offering an insight into the pathogenetic events which may underlie neoplastic clonal evolution and disease progression. We describe three cases of DLBL presenting with isolated marrow disease, a rare primary finding in this lymphoma. All three cases showed involvement of blood and bone marrow without evidence of splenic or lymph node involvement on imaging studies. Histological and immunophenotypic findings were similar in all three cases, outlining the phenotypic maturity of this disease. Cytogenetic analysis revealed complex karyotypes in the two cases examined. M-FISH (multicolour fluorescent in situ hybridization) performed on bone marrow from case 1 showed several cryptic translocations not evident on G-banding, including a novel translocation between 2p and 9p, and an unbalanced translocation between 14q and 11q. Cytogenetic analysis in case 2 showed abnormalities involving 7q, 9p at the site of the INK4a gene, and the bcl-2 locus, findings confirmed by M-FISH. These cases serve to highlight the biological and cytogenetic heterogenity of DLBL and emphasize the need for complementary investigations in the characterization of this entity.

Adult↗
PubMed2005

Blast count and cytogenetics correlate and are useful parameters for the evaluation of different phases in chronic myeloid leukemia.

Staging of chronic myeloid leukemia (CML) phases is based on cytomorphological criteria that vary considerably between different staging systems. Thus, staging of CML is heterogeneous and causes problems with respect to the comparison of therapeutical strategies and clinical outcome. We evaluated 59 patients with CML in different stages of the disease. In order to define which cytomorphological parameters correlate with cytogenetics we investigated cytomorphology and cytogenetics in parallel in all cases. As a result, bone marrow blast count demonstrated a highly significant correlation with the respective cytogenetic results of the patients and was clearly linked to the frequency and complexity of clonal evolution. We therefore propose to focus staging systems of CML on the correlation of the percentage of bone marrow blasts and the cytogenetic results.

Blast Crisis↗
PubMed2005

Clinical implications of blast immunophenotypes in myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are malignant disorders of hematopoietic cells. For many neoplasms, immunophenotype data of the neoplastic cells provide valuable information in clinical practice. However, the clinical values of immunophenotype data have not yet been firmly established for MDS. Since MDS blasts are not predominant in the bone marrow and peripheral blood, which makes reliable immunophenotyping of blasts difficult, we used a newly developed density-centrifugation reagent to generate blast-enriched MDS samples for phenotyping. The key findings of our study, which phenotyped blasts from 116 patients with MDS or acute leukemia transformed from MDS, were the following. (1) MDS blasts were usually CD34( + )CD38( + )HLA-DR( + )CD13( + )CD33( + )CD2(-)CD3(-)CD5(-)CD8(-)CD19(-)CD20(-) in flow cytometric analysis and often lacked myeloperoxidase in cytochemistry, regardless of the MDS subtype. (2) MDS blasts showed asynchronous expression of antigens (expression of both stem cell antigens and antigens of mature myeloid cells). (3) During disease progression of MDS, phenotypic clonal evolution (transition from blasts with a relatively mature phenotype to blasts with a more immature phenotype) occurred in at least some cases. (4) CD7-positivity was an independent variable associated with a short survival in MDS. Further studies of blast immunophenotypes will deepen our understanding of MDS and hopefully improve the clinical approach to these intractable disorders.

Antigens, CD↗
PubMed2000

Molecular and environmental causes of cancer.

The multistep, clonal evolution model of cancer predicts fundamental mechanisms by which chemicals may influence the cancer process. These are illustrated by studies of the mechanisms of induction of carcinogenesis by estrogens and the inhibition of carcinogenesis by caloric restriction.

Carcinogens, Environmental↗
PubMed1995

B-cell chronic lymphocytic leukemia followed by high grade T-cell lymphoma. An unusual variant of Richter's syndrome.

A 70-year-old woman with a 2-year history of B-cell chronic lymphocytic leukemia (CLL) developed headache, fever, chills, and weakness. Bone marrow examination revealed both CLL and large cell immunoblastic lymphoma (Richter's syndrome). As expected, the CLL was of B-cell lineage. The neoplasm expressed low-density monotypic IgM lambda, the pan-B-cell antigens CD19, CD20, and CDw75, and the CD5 and CD43 antigens. The large cell immunoblastic lymphoma was of T-cell lineage, positive for the CD45RB, CD3, CD45RO, and CD43 antigens, and negative for the CD20 and CDw75 antigens. Both neoplastic components were negative for Epstein-Barr virus RNA and latent membrane protein. Although 3% to 5% of patients with B-cell CLL may develop higher-grade lymphoma, usually the lymphoma is of B-cell lineage and often represents a histologic manifestation of clonal evolution. Less commonly, B-CLL patients may develop transformation to a higher grade tumor that resembles Hodgkin's disease. Both the usual form of Richter's syndrome and particularly the Hodgkin's variant of Richter's syndrome may be associated with Epstein-Barr virus. Patients with B-cell CLL rarely develop a higher grade lymphoma of T-cell lineage. To our knowledge, only one other example has been reported in the literature. Epstein-Barr virus was not associated with either neoplasm in this case.

Aged↗
PubMed1997

Isolated 13q14 abnormalities and normal karyotypes are associated with typical lymphocyte morphology in B-cell chronic lymphocytic leukemia.

Peripheral blood lymphocyte morphology and karyotype were correlated across the spectrum of cytogenetic abnormalities in 78 previously karyotyped cases of B-cell chronic lymphocytic leukemia (CLL). Cases were classified according to French-American-British morphologic criteria as typical CLL or CLL, mixed-cell type; the latter category was divided into CLL with a mixture of small and large cells and CLL with increased prolymphocytes (CLL/PL). Other leukemic lymphoproliferative disorders were excluded from this analysis. CLL cases with normal karyotypes were more likely to demonstrate typical morphology than those with clonal abnormalities (P = .042). In addition, all six cases containing isolated 13q14 abnormalities had typical morphology, compared with six of 16 other isolated abnormalities (P = .009), including one of seven cases of isolated trisomy 12. In contrast with the cases of isolated 13q14 changes, only seven of 17 cases with 13q14 as part of complex abnormalities had typical morphology (P = .012). Trisomy 12 was associated with mixed-cell morphology, particularly CLL/PL, consistent with previous reports. We conclude that isolated 13q14 abnormalities and normal karyotype are associated with typical CLL morphology, while other clonal abnormalities, including trisomy 12, are associated with mixed-cell morphology. These results further support the concept of distinct CLL subgroups based on karyotype. Furthermore, the association of trisomy 12 and complex abnormalities with mixed-cell morphology may have implications for clonal evolution in CLL.

Aged↗
PubMed1985

Small lymphocytic lymphoma. Morphologic and immunologic progression.

The large cell lymphoma (LCL) that occurs in patients with chronic lymphocytic leukemia (Richter's syndrome) has generally been shown to be of the same light chain type as the original chronic lymphocytic leukemia (CLL). The authors now report on a patient with diffuse well-differentiated lymphocytic lymphoma (WDL) of the kappa light chain type who in the course of his illness first had the blood picture of CLL and then developed malignant lymphoma of large cell ("histiocytic") type, which expressed lambda light chains. Despite an extensive multiparameter investigation, we could not determine with certainty whether the presence of two morphologically and immunologically different lymphomas represented proliferation of two distinctly separate clones or whether it represented clonal evolution of the disease with an alteration in immunoglobulin light chain associated genes. The results of the study, however, suggest that the development of lymphoma with expression of a different immunoglobulin light chain may not necessarily indicate the occurrence of a second primary. This study also illustrates the necessity for sequential lymph node biopsies to document progression of disease in patients with low-grade lymphoproliferative disorders and indicates that the immunologic phenotype of a B-cell neoplasm in a given patient should not be assumed to remain constant.

Antigens, Surface↗
PubMed1989

Dual parameter analysis of myeloma cells by flow cytometry. DNA content of cells containing monotypic cytoplasmic immunoglobulin.

Dual-parameter flow cytometric analysis of monotypic cytoplasmic immunoglobulin (CIg) and DNA content on 15 myeloma marrows allowed S-phase determination of the CIg(+) tumor separately from the CIg(-) hematopoietic cell pool. The median percentage of the CIg(+) cells in S-phase was 2% compared with 5% for the CIg(-) cells. The median survival of patients with more than 2%, and those with 2% or less CIg(+) S-phase cells was 2 months and more than 13 months, respectively, from the time of study. Ploidy analysis identified four patterns of plasma cell DNA content: entirely hyperdiploid, entirely diploid, combined diploid and tetraploid stemlines, and tumors containing diploid and aneuploid CIg(+) cells. A monotypic CIg(+) double stemline myeloma was distinguished from two aneuploid tumors containing admixed normal, diploid polyclonal plasma cells. This technique provides an improved and expedient means for determining the proliferating fractions of myeloma cells and enhances recognition of double stemline tumors and clonal evolution in myeloma.

Cytoplasm↗
PubMed1995

Mechanisms involved in the immortalization of mammalian cells by ionizing radiation and chemical carcinogens.

Immortalization is a prerequisite for the clonal evolution and malignant transformation of normal mammalian cells in culture. In order to gain a mechanistic insight into the genetics of carcinogen-induced cellular immortality, a cell culture assay has been developed based on the use of freshly explanted Syrian hamster dermal (SHD) fibroblasts. The relative efficacies of a variety of chemical and physical carcinogens at immortalizing SHD cells (against a zero background of spontaneous immortalization) were compared. Ionizing radiation and nickel chloride appeared to be more effective as immortalizing agents than powerful point mutagens, suggesting (but not proving) that clastogenic damage may be more significant in the immortalization process than point mutation. Frequencies of induced immortality (10(-6)-10(-7)/treated cell) were arguably consistent with a direct mutational mechanism involving a single genetic target. However, detailed cytogenetic characterization of a panel of newly immortalized cell lines revealed no non-random chromosomal alterations in the cells at the level of G-banding. Furthermore, additional experiments with the SHD system have provided confirmatory evidence that immortalization can occur as an indirect consequence of carcinogen exposure following an induced high frequency change in the treated population, rather than through direct targeted mutagenesis. Previous somatic cell genetic studies have suggested the possibility that a target gene for immortalization exists on the human and Chinese hamster X chromosomes. Here we provide strong evidence that the normal SHD X chromosome displays powerful senescence-inducing properties when introduced, by microcell transfer, into newly immortalized SHD recipients. These results suggest that induction of the immortal phenotype in SHD cells by carcinogens results primarily from functional inactivation of a senescence gene which may be X-linked. One possible mechanism for senescence gene inactivation consistent with our observations is through a sub-microscopic interstitial genetic deletion. However, the considerable efficacy of nickel (a human carcinogen) as an immortalizing agent at nonmutagenic doses raises the alternative possibility that immortalization may occur through an epigenetic mechanism.

Animals↗
PubMed2000

The role of senescence and immortalization in carcinogenesis.

Normal somatic cells are able to divide only a limited number of times before they become senescent. The occurrence of intratumoral cell death and the need for clonal evolution mean that many more cell divisions are required for tumorigenesis than is possible unless cells breach the senescence proliferation barrier and become immortalized. Senescence may therefore be a major tumor suppressor mechanism. During the past decade the study of senescence and immortalization has entered the mainstream of cancer research. A major reason for the current interest in this subject is the observation that most cancers have an activated telomere maintenance mechanism, a marker of immortalization. It has also been found that some of the most common genetic changes known to occur in cancer have a key role in the immortalization process.

Animals↗
PubMed2005

Tumor suppressor genetics.

The observation that mutations in tumor suppressor genes can have haploinsufficient, as well as gain of function and dominant negative, phenotypes has caused a reevaluation of the 'two-hit' model of tumor suppressor inactivation. Here we examine the history of haploinsufficiency and tumor suppressors in order to understand the origin of the 'two-hit' dogma. The two-hit model of tumor suppressor gene inactivation was derived from mathematical modeling of cancer incidence. Subsequent interpretations implied that tumor suppressors were recessive, requiring mutations in both alleles. This model has provided a useful conceptual framework for three decades of research on the genetics and biology of tumor suppressor genes. Recently it has become clear that mutations in tumor suppressor genes are not always completely recessive. Haploinsufficiency occurs when one allele is insufficient to confer the full functionality produced from two wild-type alleles. Haploinsufficiency, however, is not an absolute property. It can be partial or complete and can vary depending on tissue type, other epistatic interactions, and environmental factors. In addition to simple quantitative differences (one allele versus two alleles), gene mutations can have qualitative differences, creating gain of function or dominant negative effects that can be difficult to distinguish from dosage-dependence. Like mutations in many other genes, tumor suppressor gene mutations can be haploinsufficient, dominant negative or gain of function in addition to recessive. Thus, under certain circumstances, one hit may be sufficient for inactivation. In addition, the phenotypic penetrance of these mutations can vary depending on the nature of the mutation itself, the genetic background, the tissue type, environmental factors and other variables. Incorporating these new findings into existing models of the clonal evolution will be a challenge for the future.

Animals↗
PubMed1998

Structural and numerical chromosomal aberrations in a metabolically competent human lymphoblast cell line (MCL-5).

MCL-5 cells are Epstein Barr virus-transformed human lymphoblasts which have been genetically engineered for use in mutagenicity testing. We have examined the modal chromosome number, karyotype and spontaneous micronucleus (MN) and sister chromatid exchange (SCE) frequencies of the cell line. Replicate experiments were conducted on two different shipments purchased from Gentest Corp. Although the modal chromosome number was 48 (range 40-54, n = 400 metaphases) for both cell shipments, the second stock showed greater variation in chromosome number than the first. A total of 60 G-banded metaphase cells was analyzed and seven karyotypes were prepared. Consistent structural abnormalities (translocations, deletions and isochromosomes) were found involving the X chromosome and seven autosomes (1-3, 5, 6, 9 and 11). The karyotype typical of this cell line was: 48,der(X)t(X;?)(p22.3;?)Y,t(1;2)(q23;p23),del(3)(q12q21), + i(3q),t(5;6) (q31;p23),+i(9p),der(11)t(11;13)(q23;q12). The mean MN frequency was 41.8 MN/1000 binucleate cells (n = 5000). When compared with our historical controls for primary lymphocyte cultures this number (41.8) is significantly (8.4-fold) higher. The mean SCE frequency was 7.3 per metaphase (n = 100). We observed a hyperdiploid chromosome number of 48 in the majority of metaphase spreads, indicating a significant deviation from the normal diploid number characteristic of the parent cells (RPMI 1788) established in 1969. The variation in chromosome number distribution observed between shipments suggests the potential for further changes. The elevated MN frequency suggests that evaluating mutagenicity using this cytogenetic end-point may require excessive dosing to produce a significant response over background. We conclude that careful interpretation of cytogenetic end-points is necessary when using MCL-5 cells in the light of the possibility of clonal evolution presented here.

Adult↗
PubMed2002

The significance of telomerase activation and cellular immortalization in human cancer.

Repression of telomerase in the somatic tissues of humans, and probably other long-lived mammals, appears to have evolved as a powerful protective barrier against cancer. Immortalization in vitro of normal human cells that lack telomerase involves the reactivation of telomerase or, rarely, an alternative (ALT) mechanism for maintaining telomeres. Inactivation of the effectors of replicative senescence, i.e. genes encoding one or more elements of the p16/pRB and/or ARF/p53/p21 anti-proliferative pathways, is required for telomerase depression leading to immortalization. Regulation of telomerase in normal human cells is mediated primarily by transcriptional repression of hTERT, the gene encoding the catalytic subunit of telomerase. Rodent cells do not possess stringent controls on telomerase activity in the soma and this explains why they are so readily immortalized and transformed in culture compared with their human counterparts. Because active telomerase has been found to exist in the proliferative compartments of self-renewing tissues, it is not yet clear whether the telomerase present in 90% of human cancers exists as a consequence of selection of pre-existing telomerase-positive cells during carcinogenesis or through induction of hTERT expression in cells in which it is normally tightly repressed. In support of the latter, chromosome transfer techniques have revealed the presence of genes on normal human chromosomes that are able to extinguish hTERT transcription in cancer cells and induce them to undergo senescence. It is clear that telomerase is obligatory for continuous tumour cell proliferation, clonal evolution and malignant progression. Telomerase therefore represents an attractive target at which to aim new anti-cancer drugs. Results with a variety of telomerase inhibitory strategies in human cancer cells have confirmed that its functional inactivation results in progressive telomere shortening, leading to growth arrest and/or cell death through apoptosis. Promising candidate small molecule inhibitors are beginning to emerge that will form the basis for anti-telomerase drug development.

Animals↗
PubMed1986

Estrogen receptors and breast cancer.

The literature indicates that relationships between epidemiologic variables and estrogen receptor activity are not clearly defined. Conflicting and unconfirmed results have been published. Most studies have been based on clinical case series rather than on carefully conducted population-based epidemiologic investigations. In addition, previous reports have not generally considered the potential role of confounding and interaction in the interpretation of the associations reported between estrogen receptor status and risk factors for breast cancer. Given these considerations, the need for further research in this area is obvious. Application of an estrogen receptor scheme (positive vs. negative) for defining breast cancer may allow delineation of cases that may appear quite similar but that represent two different types of disease. Estrogen receptor-positive and estrogen receptor-negative breast cancer behave differently biologically, have different treatment and prognostic implications, and thus may also possibly have different risk factor patterns. Moreover, the extent to which receptor status reflects effects associated with exposure, the disease process, or host influences is not clearly understood. There is some evidence that estrophilin is a biochemical marker of tumor differentiation. Moolgavkar et al. suggested that all breast cancers are initially estrogen receptor-positive, but that as the tumor undergoes clonal evolution and becomes more undifferentiated, the ability to express estrophilin is lost in some cases. If this is true, estrogen receptor results may reflect temporal changes in the biologic characteristics of the tumor as it progresses from a well differentiated to a poorly differentiated state. Receptor status could also reflect changes in host resistance and tumor aggressiveness. This concept is consistent with previous observations that anaplastic, rapidly growing cancers are less likely to be receptor-positive. It has not been established whether estrogen receptor-negative tumors represent an advanced stage of the disease or arise de novo. Clinical studies have failed to demonstrate a relationship between extent of disease at diagnosis and receptor results. Estrophilin concentrations also are apparently not related to stage of disease, lending no support for the notion that receptor level declines with progression of the disease. It is possible that certain etiologic factors lead to the natural selection and growth of receptor-negative cells and that receptor negativity is an early, inherent characteristic of some breast cancers.(ABSTRACT TRUNCATED AT 400 WORDS)

Breast Neoplasms↗
PubMed2001

Pulmonary Langerhans' cell histiocytosis: molecular analysis of clonality.

Pulmonary Langerhans' cell histiocytosis (LCH) is a form of Langerhans' cell disease that primarily affects smokers in the third to fifth decade. Extrapulmonary manifestations are rare. Its clinical course is typically characterized by stabilization or regression of bilateral micronodular infiltrates seen on chest radiographs; progression to honeycomb fibrosis is rare. Because the clinical course of pulmonary LCH is distinct from systemic multiorgan LCH, currently thought to be a clonal proliferative disorder, we examined the X-linked polymorphic human androgen receptor assay (HUMARA) locus to assess clonality in female patients with one or more discrete LCH cell nodules in open lung biopsies. Langerhans' cells (LCH cells) were excised from formalin-fixed, paraffin-embedded tissue by microdissection to assure a relatively pure cellular population, and studies for differential methylation patterns at the HUMARA locus were performed. Twenty-four nodules in 13 patients were evaluated. Seven (29%) were clonal and 17 (71%) were nonclonal. Of six cases with multiple discrete nodules, three (50%) showed a nonclonal LCH cell population. In one biopsy with five nodules, two nodules were clonal with one allele inactivated, one nodule was clonal with the other allele inactivated, and two nodules were nonclonal. In contrast to systemic LCH, pulmonary LCH appears to be primarily a reactive process in which nonlethal, nonmalignant clonal evolution of LCH cells may arise in the setting of nonclonal LCH cell hyperplasia. Cigarette smoking may be the stimulus for pulmonary LCH in contrast to other forms of LCH.

Adult↗
PubMed1996

Testicular cancer.

The rising rate of germ cell cancer of the testis over the past decade has been demonstrated to be occurring predominantly in the younger age group (15 to 19 years) in association with earlier onset of puberty and earlier onset of regular sexual activity. Chemicals and viruses, with their atrophogenic effect, remain the main candidates for inducing the final common pathway of tumor development and clonal evolution, ie, gonadotropin-driven mitosis in spermatogonia. The possibility of different genetic mechanisms regulating susceptibility and resistance to these two extreme causes of gonadal atrophy in families is raised by the failure of a genome screen in a series of sibling pairs with testicular cancer to identify a single significant linkage group. Studies demonstrating high levels of non-mutated p53 protein and rapid induction of apoptosis by chemotherapy provide a new insight into the cause of the exquisite chemosensitivity of these tumors. Durable responses to paclitaxel and in vitro activity in response to temezolamide provide further evidence of the plethora of agents that work against these tumors, although no new first-line therapeutic approaches have been reported recently. The most important clinical trial studied good-risk patients and demonstrated that to gain the benefit of reducing treatment time from 12 to 9 weeks it is essential to retain bleomycin in the BEP (bleomycin, etoposide, and cisplatin) regimen. The final new idea to emerge recently comes from a series of papers on management of primary tumors in patients with a solitary testis and the possible use of organ-conserving surgery plus postoperative radiation. Another study did suggest it might be possible to use preoperative chemotherapy in those wishing to retain spermatogenesis.

Adolescent↗
PubMed1996

Detection of cellular heterogeneity by DNA ploidy, 17 chromosome, and p53 gene in primary carcinoma and metastasis in a case of ovarian cancer.

An unusual case of a patient with ovarian carcinoma carrying the p53 point mutation in both metastases (omentum and lymph node), but not in the primary tumor, is described. The presence of a p53 single mutation (G:A) at the second base of codon 248 was examined by polymerase chain reaction-amplification refractory mutation system (PCR-ARMS) analysis. This case was examined also by fluorescent in situ hybrization (FISH) analysis and flow cytometry (FCM) to obtain further information at the single cell level and to detect heterogeneity within a population of cells. FCM analysis evidenced the same multiple aneuploid cell subpopulations in primary and in metastatic samples showing the presence of a cellular heterogeneity. FISH analysis showed a disomic condition for the 17 chromosome in the primary and in one metastasis, while in the other metastasis a monosomic together with a disomic subpopulation was revealed. Our results confirm the independent clonal evolution of the metastasis. The late mutation event observed only in metastatic specimens suggests the hypothesis that in the primary tumor the wild-type gene either does not perform its control role for unknown genetic structural events or the p53 gene in this case does not play a critical role in carcinogenesis.

Base Sequence↗
PubMed1997

Comparative analysis of detection systems for evaluation of PCR amplified immunoglobulin heavy-chain gene rearrangements.

Four different detection systems were compared for evaluation of polymerase chain reaction (PCR) amplified immunoglobulin heavy-chain gene rearrangements in acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL) of B-cell lineage. In 63.0% of the fragments detected by ethidium bromide stained agarose gel electrophoresis (Agarose-EtBr) the sensitivity was insufficient to separate the specific clonal population from the background of normal B cells. Using polyacrylamide gel electrophoresis (PAGE), PAGE combined with single-strand conformation polymorphism (PAGE-SSCP) and PhastGel-SSCP (Phast-SSCP) analysis with silver staining, the resolution was improved and the majority of the inconclusive amplicons were elucidated. However, Phast-SSCP displayed a slightly higher detection level compared to PAGE and PAGE-SSCP. According to our findings PAGE-SSCP and Phast-SSCP were superior to agarose-EtBr and PAGE in detecting new emerging clones and clonal evolution.

DNA, Neoplasm↗