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Biomedical subjects

M Raffeld

Publications and source records attributed to M Raffeld.

At least 91 records · Page 5Linked to original sources
PubMed1996

The MDM2 oncoprotein is overexpressed in rhabdomyosarcoma cell lines and stabilizes wild-type p53 protein.

MDM2 gene overexpression has been implicated in the pathogenesis of human neoplasia via inhibition of the p53 tumor-suppressor function. To investigate the potential involvement of the MDM2 oncogene in the pathogenesis of childhood rhabdomyosarcoma (RMS) we studied MDM2 abnormalities in six RMS cell lines in correlation with the p53 status. Three showed overexpression of MDM2 mRNA and protein, one with concomitant MDM2 gene amplification. All three lacked p53 mutation and expressed low levels of p53 mRNA but exhibited elevated p53 proteins. Double immunostaining revealed that the overexpressed MDM2 and p53 proteins were co-localized to the same cell nuclei. Furthermore, the two proteins were physically associated, as shown by co-immunoprecipitation and Western blot analysis. The half-life of the p53 protein was prolonged in the MDM2-expressing RMS cells. The extended half-life wildtype p53 protein and its complex formation with the elevated MDM2 suggest that the underlying mechanism for p53 protein accumulation in these cell lines is p53 stabilization by an overabundant MDM2 protein. The overexpressed MDM2 protein had a short half-life. The three remaining RMS cell lines exhibited low MDM2 mRNA and protein levels and carried p53 mutations. This study suggest that MDM2 overexpression represents an alternative mechanism for p53 inactivation in a subset of childhood RMS without p53 mutations. The results further indicate that the elevated MDM2 protein is responsible for wildtype p53 protein accumulation via stabilization.

Blotting, Northern↗
PubMed1996

Detection of HHV-8/KSHV DNA sequences in AIDS-associated extranodal lymphoid malignancies.

Herpesvirus-like DNA sequences have been identified in a high proportion of both AIDS-associated and classical Kaposi's sarcoma, and in a small percentage of AIDS-associated malignant lymphomas. To determine the extent of involvement of this new agent designated HHV-8 (human herpesvirus type 8) or KSHV (Kaposi's sarcoma-associated herpesvirus) in human malignant lymphomas, we analyzed 24 AIDS-associated lymphoid malignancies and 100 non-AIDS-associated lymphomas by PCR and Southern blot analysis. Three of 24 lymphoid malignancies from patients with AIDS demonstrated HHV-8 sequences by Southern blot and PCR analyses. The fourth was positive by PCR only. None of the non-AIDS-associated lymphomas contained HHV-8 sequences. All three Southern blot positive samples were derived from extranodal regions, two from pleural effusions, and one from a soft tissue mass in the thigh. This latter patient initially presented with a pleural effusion. The fourth PCR positive but Southern blot negative tumor was from a gingival lymphoma in a patient with a history of Kaposi's sarcoma. All tumors positive for HHV-8 were also positive for EBV. These results confirm a recent report that this novel herpesvirus may play a role in AIDS-associated lymphomas especially in those with body cavity presentation.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Use of CD23 (BU38) on paraffin sections in the diagnosis of small lymphocytic lymphoma and mantle cell lymphoma.

The CD23 antigen is a low-affinity immunoglubulin E receptor that is expressed during B-cell activation. Recently, it has been shown to be of diagnostic utility in distinguishing between small lymphocytic lymphoma (SLL) and mantle cell lymphoma (MCL), two entities that can have similar morphologic and immunophenotypic features. Such studies, however, generally required viable cells in cell suspension or cryostat sections for detection of CD23. We evaluated staining for the CD23 antigen in paraffin sections, using BU38, an antibody that detects a fixation-resistant epitope of the antigen. We analyzed 44 SLLs, 3 lymphoplasmacytoid lymphomas, and 39 MCLs. Staining was performed on formalin- or B5-fixed paraffin-embedded tissue sections using L26 (CD20), CD3, Leu22 (CD43), and BU38 (CD23) antibodies. All of the cases were of B-cell phenotype (CD20+), and 42/44 SLLs, 3/3 lymphoplasmacytoid lymphomas, and 33/39 MCLs coexpressed the CD43 antigen. CD23 was positive in 41 (93%) of 44 SLLs. The majority of neoplastic cells (75% or more) stained positively, with a membranous pattern of staining. The staining was moderate in intensity and easily interpreted. Only 1/39 MCLs and 1/3 lymphoplasmacytoid lymphomas were CD23 positive. CD23-positive follicular dendritic cells were, however, present in all of the MCLs, either in residual follicles or in large, disordered meshworks. These results demonstrate that the BU38 antibody can detect CD23 on the cells of SLLs in paraffin sections and that this antibody can have diagnostic utility in routine diagnosis.

Biomarkers, Tumor↗
PubMed1995

Human immunodeficiency virus 1 envelope-initiated G2-phase programmed cell death.

Despite intensive investigation, no clearly defined mechanism explaining human immunodeficiency virus (HIV)-induced cell killing has emerged. HIV-1 infection is initiated through a high-affinity interaction between the HIV-1 external envelope glycoprotein (gp120) and the CD4 receptor on T cells. Cell killing is a later event intimately linked by in vitro genetic analyses with the fusogenic properties of the HIV envelope glycoprotein gp120 and transmembrane glycoprotein gp41. In this report, we describe aberrancies in cell cycle regulatory proteins initiated by cell-cell contact between T cells expressing HIV-1 envelope glycoproteins and other T cells expressing CD4 receptors. Cells rapidly accumulate cyclin B protein and tyrosine-hyperphosphorylated p34cdc2 (cdk1) kinase, indicative of cell cycle arrest at G2 phase. Moreover, these cells continue to synthesize cyclin B protein, enlarge and display an abnormal ballooned morphology, and disappear from the cultures in a pattern previously described for cytotoxicity induced by DNA synthesis (S phase) inhibitors. Similar changes are observed in peripheral blood mononuclear cells infected in vitro with pathogenic primary isolates of HIV-1.

Apoptosis↗
PubMed1995

The investigation of Epstein-Barr viral sequences in 41 cases of Burkitt's lymphoma from Egypt: epidemiologic correlations.

BACKGROUND: Epstein-Barr virus (EBV) is associated with many human neoplasms, including Burkitt's lymphoma (BL). Endemic BL in central Africa is more often EBV-associated than BL in the United States, where seroconversion for EBV occurs somewhat later than in Africa. Therefore, the EBV association rate in BL may correlate more with the socioeconomic status of the population studied, which influences the age of EBV seroconversion, than with such factors as malaria, which may relate to the overall higher incidence rate in endemic regions. METHODS: Forty-one patients with BL in Egypt, which differs both climatically and racially from central African countries (i.e., Kenya, Uganda) where BL is endemic, were analyzed. All biopsies were evaluated for EBV-encoded RNAs (EBER1) by RNA in situ hybridization, analyzed for p53 protein expression using the monoclonal antibody D07, and immunophenotyped using a panel of monoclonal antibodies that included L26 (CD20), Leu 22 (CD43), and A6 (CD45RO). Twelve cases were evaluable for EBV subtype by polymerase chain reaction with EBV-specific primers. RESULTS: The median age at diagnosis was 9 years (range, 2-22 years). The biopsy site was extranodal in 29 patients and nodal in 12 patients. All 41 cases were documented as B-cell neoplasms. A hybridization signal for EBER1 RNA was identified in greater than 95% of the neoplastic cells in 30 of 41 cases (73%), whereas no signal was observed in 11 cases (27%). Epstein-Barr virus subtype 1 was found in 10 patients, subtype 2 in two patients. Immunostaining for p53 was observed in greater than 5% of the neoplastic cells in 9 of 37 cases (24%). No significant correlation was observed between EBV positivity and sex, biopsy site, or p53 immunostaining. CONCLUSIONS: The prevalence of EBV in BL from Egypt is slightly lower than in BL in endemic regions, but significantly higher than in sporadic BL. Epstein-Barr virus positivity probably reflects the socioeconomic status of the patient population, and age at seroconversion. The prevalence of EBV subtype 1 suggests that immunodeficiency does not play a role in Egyptian Burkitt's lymphoma, in contrast to endemic Burkitt's lymphoma, in which holoendemic malaria is thought to contribute to immunodeficiency, a higher incidence rate, and the observed prevalence of subtype 2.

Adolescent↗
PubMed1995

Analysis of the t(2;5)(p23;q35) translocation by reverse transcription-polymerase chain reaction in CD30+ anaplastic large-cell lymphomas, in other non-Hodgkin's lymphomas of T-cell phenotype, and in Hodgkin's disease.

The t(2;5)(p23;q35) translocation is associated with a high percentage of anaplastic large-cell lymphomas (ALCL) of T- or null-cell phenotype. This translocation was recently cloned and results in the fusion of the nucleophosmin gene (NPM) on chromosome 5q35 to a novel tyrosine kinase-encoding gene designated anaplastic lymphoma kinase (ALK) on chromosome 2p23. Using a sensitive and specific reverse transcription-polymerase chain reaction (RT-PCR) assay to detect the NPM/ALK fusion transcript, we assessed the involvement of NPM/ALK in a series of histologically and immunohistochemically confirmed ALCL, in non-ALCL aggressive non-Hodgkin's lymphomas of T-cell phenotype, and in Hodgkin's disease (HD) to better define the morphologic spectrum of disease associated with this translocation. Twenty-four cases of ALCL were selected on the basis of CD30 positivity and histologic features. Seventeen cases presented as classical nodal and extranodal disease, four cases presented as primary cutaneous disease, and three were associated with human immunodeficiency virus (HIV) infection. As ALCL may show overlapping histology with both HD and other aggressive non-Hodgkin's lymphomas, particularly of T-cell phenotype (T-NHL), we also studied 34 cases of HD and 19 of T-NHL. NPM/ALK chimeric transcripts of identical size were detected in 11 of the 24 (46%) cases of ALCL. NPM/ALK fusion transcripts were found in 11 of 17 (65%) classical ALCL cases but were not detected in the four primary cutaneous cases of ALCL or in the three HIV-related ALCL cases. In addition, NPM/ALK transcripts were not detected in any of the 34 cases of HD or in the 19 cases of T-NHL. These data indicate that NPM/ALK fusion transcripts occur in a high percentage of classical nodal ALCL (65%). In addition, these data strongly suggest that ALCL, as defined in this study, is not pathogenetically related to either HD disease or the majority of other types of aggressive T-NHL. This is a US government work. There are no restrictions on its use.

Adolescent↗
PubMed1995

Analysis of LAZ3 (BCL-6) status in B-cell non-Hodgkin's lymphomas: results of rearrangement and gene expression studies and a mutational analysis of coding region sequences.

The LAZ3 gene encodes a novel zinc-finger protein that shares homology with several Drosophila transcription factors. This gene was identified by its disruption in translocations involving chromosome 3q27 in diffuse large-cell lymphomas. To assess the frequency and role of this gene's involvement in lymphomagenesis and tumor progression, we examined a series of 170 cases of non-Hodgkin's lymphomas of B-cell lineage for LAZ3 gene rearrangement, expression, and mutation. The cases included 35 de novo diffuse aggressive lymphomas (DAL; 19 large-cell, 4 mixed-cell, and 12 large-cell immunoblastic), 52 transformed aggressive lymphomas derived from follicular lymphomas (TFL), 42 indolent follicular lymphomas (FL), 14 mantle cell lymphomas (MCL), and 27 small noncleaved cell lymphomas (SNCL). LAZ3 rearrangements were found in 10 DAL (28.6%), 9 TFL (17.3%), and 6 FL (14.3%), but not in any of the SNCL or MCL. LAZ3 rearrangement was not exclusive of bcl-2 rearrangement. Most rearrangement breakpoints mapped to a 10-kb BamHI-Xba I fragment located 5' to the LAZ3 coding sequence, consistent with previously reported breakpoint locations. Northern analysis of both rearranged and nonrearranged B-cell lymphoma cases showed similar levels of a transcript of approximately 3.8 kb, indicating that LAZ3 is broadly expressed in B-cell tumors and is not confined to rearranged cases. To investigate whether mutation of the LAZ3 gene might contribute to a potential role for this gene in lymphomagenesis, we screened the coding sequences of 13 rearranged cases, 6 nonrearranged cases, and 13 hematopoietic tumor cell lines. Although three probable polymorphisms were identified, mutations were detected in only 2 rearranged cases. Only 1 of these resulted in an amino acid substitution. Two cell lines (SU-DHL4 and Molt-4) also contained mutations; only one resulted in an amino acid substitution. We conclude (1) that LAZ3 rearrangements occur in a significant fraction of de novo DAL as well as in a smaller subset of indolent and transformed follicular lymphomas; (2) that LAZ3 message is expressed in both rearranged and nonrearranged B-cell lymphomas; and (3) that mutation of the LAZ3 gene does not contribute to its putative oncogenic role in most 3q27 translocated B-cell lymphomas.

Base Sequence↗
PubMed1995

Involvement of CDKN2 (p16INK4A/MTS1) and p15INK4B/MTS2 in human leukemias and lymphomas.

CDKN2 (p16INK4A/MTS1) and p15INK4B/MTS2 have been shown recently to be potent inhibitors of the cyclin D/cyclin-dependent kinase 4 complex. Both genes are candidates for the putative tumor suppressor gene located at chromosome 9p21. We examined a series of 14 hematopoietic cell lines and 117 primary lymphoid tumors for deletion and mutation of these genes. The primary tumors included 65 T-cell malignancies and 52 B-cell malignancies. The cell line study revealed 4 of 4 T-ALL lines to have homozygous deletions of CDKN2. Two of the 4 lines also showed homozygous deletions of MTS2, while the remaining 2 lines retained both MTS2 alleles. In the primary tumors, homozygous deletions of both CDKN2 and MTS2 were found in 35% of the T-ALL/lymphoblastic lymphoma (8 of 23). Homozygous deletions of both genes also occurred in 1 of 3 precursor B-ALLs. PCR-single strand conformational polymorphism analysis of CDKN2 exons 2 and 3 and MTS2 exon 2 failed to demonstrate mutations in either CDKN2 or MTS2 in any of the T- or B-cell malignancies, with two possible exceptions. These results are consistent with a role for CDKN2 and/or MTS2 in the pathogenesis of some lymphoid leukemia/lymphomas, particularly in T-ALL/lymphoblastic lymphoma.

Base Sequence↗
PubMed1995

Sequential analysis of 43 patients with non-Hodgkin's lymphoma: clinical correlations with cytogenetic, histologic, immunophenotyping, and molecular studies.

Few reports correlating specific cytogenetic abnormalities with distinct subtypes of lymphoma have performed serial studies at diagnosis and at tumor recurrence or progression. In our file of 325 cytogenetically analyzed non-Hodgkin's lymphoma (NHL) patients studied over the past decade, 43 had serial biopsies, 39 of whom had at least two successful preparations; of the 43, nine had one and 32 had two or more cytogenetically abnormal specimens. In this study, we correlated cytogenetic, histopathologic, molecular, and clinical parameters. Patients with low-grade lymphomas were as likely as patients with intermediate- or high-grade lymphomas to acquire new chromosomal abnormalities with time (16 of 23 patients as compared with 7 of 16; P2 = .11, chi 2 test). In four patients, originally diagnosed indolent disease progressed to aggressive disease; all had t(14;18), all gained additional chromosomal abnormalities with disease progression, and three of the four expressed abnormalities associated with disease progression and/or short survival: der(18), +7, and/or +12. Cytogenetic results from early disease were compared with those obtained later in disease: in the t(14;18) group, the most common abnormalities were +7 (eight patients) and der(18) (five patients), both seen later in disease. The most common abnormalities in patients without t(14;18) were 6q deletions; they were seen in both early and late disease and were associated with significantly shorter survivals (P2 = .0014) compared with all patients without 6q deletions. Secondary chromosomal abnormalities, observed after at least one previous abnormal study, were seen in 19 of 22 t(14;18) patients and in 11 of 21 patients without t(14;18) and were associated with a poor survival (P2 = .13) compared with patients without any secondary chromosomal abnormalities. Chromosome 1 abnormalities were seen in almost half of the patients and were observed in initial specimens and early in disease as well as late in disease and as secondary abnormalities; 1q involvement was more frequent than 1p (15 versus eight patients) and was significantly associated with poor survival only in patients with intermediate-/high-grade disease; the most common breakpoints were 1q21-q22 (nine patients) and 1p36 (six patients). Breakpoints at 2q21 and 3q27-q29 were limited to patients with t(14;18) and were almost exclusively secondary in nature. Molecular studies in 24 of our patients showed discrepancies with the cytogenetic results in only three patients: two had t(14;18) but no molecular rearrangements while two patients had no visible t(14;18) but were positive for major breakpoint region (MBR) rearrangement. The presence of MBR or minor breakpoint cluster (MCR) rearrangement had no apparent effect on survival.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1995

Pulmonary malignant lymphoma of mucosa-associated lymphoid tissue (MALT) arising in a pediatric HIV-positive patient.

A malignant lymphoma arising in the lung of a pediatric HIV-positive patient exhibited histologic and clinical features of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT). Clinically, the neoplasm consisted of a 4-cm mass in the left-upper lobe of the lung of a 7-year-old girl. The lung mass was surgically resected. Monoclonal immunoglobulin heavy and light chain gene rearrangements were shown by Southern blot. Monoclonality of light chain expression was demonstrated by immunohistochemistry. Coexpression of Leu-22 (CD43) by the tumor cells supported the diagnosis of lymphoma. The remainder of the pulmonary parenchyma distal to the mass was associated with pulmonary lymphoid hyperplasia/lymphocytic interstitial pneumonitis, which may have been a predisposing factor. Gastric MALT lymphomas have recently been described in adult HIV-antibody-positive patients. Ours represents the first reported case of a pulmonary MALT lymphoma in a pediatric HIV-positive patient. In addition, at age 7, this is the youngest patient reported with a MALT lymphoma.

Child↗
PubMed1995

A link between increased transforming activity of lymphoma-derived MYC mutant alleles, their defective regulation by p107, and altered phosphorylation of the c-Myc transactivation domain.

The c-Myc protein is a transcription factor with an N-terminal transcriptional regulatory domain and C-terminal oligomerization and DNA-binding motifs. Previous studies have demonstrated that p107, a protein related to the retinoblastoma protein, binds to the c-Myc transcriptional activation domain and suppresses its activity. We sought to characterize the transforming activity and transcriptional properties of lymphoma-derived mutant MYC alleles. Alleles encoding c-Myc proteins with missense mutations in the transcriptional regulatory domain were more potent than wild-type c-Myc in transforming rodent fibroblasts. Although the mutant c-Myc proteins retained their binding to p107 in in vitro and in vivo assays, p107 failed to suppress their transcriptional activation activities. Many of the lymphoma-derived MYC alleles contain missense mutations that result in substitution for the threonine at codon 58 or affect sequences flanking this amino acid. We observed that in vivo phosphorylation of Thr-58 was absent in a lymphoma cell line with a mutant MYC allele containing a missense mutation flanking codon 58. Our in vitro studies suggest that phosphorylation of Thr-58 in wild-type c-Myc was dependent on cyclin A and required prior phosphorylation of Ser-62 by a p107-cyclin A-CDK complex. In contrast, Thr-58 remained unphosphorylated in two representative mutant c-Myc transactivation domains in vitro. Our studies suggest that missense mutations in MYC may be selected for during lymphomagenesis, because the mutant MYC proteins have altered functional interactions with p107 protein complexes and fail to be phosphorylated at Thr-58.

Alleles↗
PubMed1995

Analysis of T cell receptor-gamma gene rearrangements by denaturing gradient gel electrophoresis of GC-clamped polymerase chain reaction products. Correlation with tumor-specific sequences.

We describe a modified denaturing gradient gel electrophoresis (DGGE) procedure with a 40-nucleotide GC clamp in the polymerase chain reaction to improve resolution in amplifying T cell receptor-gamma (TCR-gamma) rearrangements. DNA from 46 cases of lymphoblastic leukemia/lymphoma, 5T cell lines, 2 B cell lines, 7 normal lymphocytes, and 3 cases of Hodgkin's disease was amplified by polymerase chain reaction. In addition, 20 cases of paraffin-embedded T cell lymphomas and 5 cases of reactive hyperplasia were also studied. Clonal TCR-gamma rearrangements were identified on DGGE by the presence of a predominant band. Results obtained from 5 T cell lines and 12 lymphoblastic leukemia/lymphomas containing known TCR-gamma gene rearrangements revealed 100% concordance in detecting clonal rearrangements between DGGE and traditional Southern blot analysis. Of the remaining 34 lymphoblastic leukemia/lymphoma cases studied by DGGE alone, 30 were positive. DGGE analysis of 10 lymphoblastic leukemia/lymphoma cases with known group IV gamma to J gamma 1 or J gamma 2 rearrangement sequences confirmed that the electrophoretic migration was dependent on the tumor-specific rearranged TCR-gamma sequence. In addition, 17 of 20 cases of paraffin-embedded T cell lymphomas were positive by DGGE, 6 of which had the clonal population also identified in fresh tissue DNA. DGGE analysis of GC-clamped polymerase chain reaction products can provide a way to more accurately detect TCR-gamma clonality of lymphoid tumors and can be applied to archival tissues.

Base Sequence↗
PubMed1994

Synergy between basic fibroblast growth factor and HIV-1 Tat protein in induction of Kaposi's sarcoma.

Basic fibroblast growth factor (bFGF) and human immunodeficiency virus type 1 (HIV-1) Tat protein synergize in inducing angiogenic Kaposi's sarcoma-like lesions in mice. Synergy is due to Tat, which enhances endothelial cell growth and type-IV collagenase expression in response to bFGF mimicking extracellular matrix proteins. The bFGF, extracellular Tat and Tat receptors are present in HIV-1-associated KS, which may explain the higher frequency and aggressiveness of this form compared to classical Kaposi's sarcoma where only bFGF is present.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Mutations in the coding region of c-MYC in AIDS-associated and other aggressive lymphomas.

Our previous studies of the translocated MYC gene in Burkitt's lymphoma showed the existence of clustered somatic mutations located in the transcriptional activation domain. We now report that aggressive lymphomas arising in the acquired immunodeficiency syndrome (AIDS) contain similar mutations and that the presence of mutations is correlated with the rearrangement of the oncogene. Mutations were also found in other de novo non-AIDS, non-Burkitt's aggressive lymphomas with MYC rearrangements. An unusual asparagine to serine mutation at codon 11 was identified in several transformed follicular lymphomas without MYC rearrangement but not in normal tissues from patients with this mutation. These findings indicate that AIDS-associated and other de novo aggressive lymphomas with the MYC gene rearrangement are subject to the same mutation and selection process that affects Burkitt's lymphomas.

Amino Acid Sequence↗
PubMed1994

Cytogenetic study of two cases with lymphoma of mucosa-associated lymphoid tissue.

Cytogenetic studies have been reported in fewer than 20 patients with lymphoma of mucosa associated lymphoid tissue (MALT). Two patients with this disease at the Clinical Center, National Institutes of health had numerical and structural chromosome abnormalities, including +12 in both cases. The clonal karyotypes observed were 48-49,XX,t(2;8)(q33;p23), +3, -10,del(10)(q23), +12, +18 [cp] and 47,X,-X,i(6p), +7, +inv(12)(p13q13). Review of cytogenetic studies from published data showed that all cases of MALT lymphoma reported to date also have both numerical and structural chromosome abnormalities, the most frequent being numerical involvement of chromosomes 3, 7, and 12. Identification of a clonal abnormality can help establish the diagnosis when differential diagnosis includes atypical hyperplasia. Although trisomy 12 has been associated with a poor prognosis in B-cell chronic lymphocytic lymphoma (B-CLL), both these patients with MALT lymphoma have had long survival: 8 and 11 years, respectively.

Chromosome Aberrations↗