Biomedical subjects

Wing C Chan

Publications and source records attributed to Wing C Chan.

At least 37 records · Page 2Linked to original sources

PubMed2005

Recent advances in the molecular diagnosis of diffuse large B-cell lymphoma.

The field of molecular diagnostics is changing and adapting to new information obtained from genetic, genomic and proteomic profiling of diseases. One of the novel technologies that has made significant impact on the molecular diagnosis of lymphoid malignancies is DNA microarray technology. It has allowed the profiling of the most common types of lymphomas, identifying distinct molecular signatures of these diseases as well as novel subtypes that cannot otherwise be identified by conventional methods. In addition, it has also allowed the construction of molecularly defined prognostic models for various types of lymphomas and to better understand the molecular mechanisms that determine the behavior of the tumor. In this review, recent advances in the molecular diagnosis of diffuse large B-cell lymphoma are highlighted, using examples of how gene expression profiling has been used in disease classification and outcome predictions. The future development of this field and its applications in the clinical arena will also be discussed.

Animals↗

PubMed2005

Composite B-cell and T-cell non-Hodgkin lymphoma of the tibia.

We report a unique case of de novo composite lymphoma in the tibia of a 35-year-old man who presented with increasingly frequent and intense pain in the right upper leg. He was otherwise healthy without significant medical history. A plain radiograph of the right leg showed a permeative lesion with alternating areas of radiolucency and radiodensity in the upper third of the tibia. Magnetic resonance imaging showed a large, heterogeneous enhancing lesion involving the medullary and cortical bone of the proximal tibia with cortical disruption and extension into the adjacent soft tissue. A biopsy showed sheets and clusters of large cells, punctuated by clusters of small, irregular lymphocytes. Flow cytometry and immunohistochemical analysis showed composite lymphoma: diffuse large B-cell lymphoma (DLBCL) and peripheral T-cell non-Hodgkin lymphoma with predominantly small cell morphologic features. The DLBCL expressed CD19, CD20, CD79a, CD5, CD10, CD23, CD38, CD117, bcl-2, and bcl-6, with monotypic expression of immunoglobulin kappa light chain. The T cells expressed CD2, CD3, CD5, CD7, and CD8, with partial loss of CD4. Clonal rearrangement of T-cell receptor gamma chain gene was found. Neither the large B cells nor the small T cells expressed Epstein-Barr virus-encoded RNA. Physical examination and radiologic studies showed no evidence of lymphadenopathy, organomegaly, or other mass lesions in the body. No peripheral lymphocytosis or bone marrow involvement was present.

Adult↗

PubMed2005

Gene expression profiling in lymphoma diagnosis and research.

Gene expression profiling in the past 5 years has generated a large amount of data on a variety of malignancies. Unique gene expression signatures have been identified for the more common types of non-Hodgkin lymphoma (NHL), including clinically and biologically important subsets that have not been defined before. In addition, molecularly defined prognosticators have also been constructed for the major types of NHL and these prognosticators provide added value to the widely used International Prognostic Index. The new information should be included in our evaluation of NHL patients, especially when conducting clinical trials. Studies are ongoing to validate and refine these diagnostic and prognostic signatures and to develop platforms that are suitable for routine clinical applications. Similar studies will be performed on the less common types of NHL to complete the molecular classification of NHLs. It is also anticipated that gene expression profiling studies will lead to the identification of novel targets for the development of new therapeutic agents for NHL.

Gene Expression Profiling↗

PubMed2005

Full clinical recovery after topical acyclovir treatment of Epstein-Barr virus associated cutaneous B-cell lymphoma in patient with mycosis fungoides.

Primary cutaneous T- and B-cell lymphomas are a heterogeneous group of diseases with varied clinical presentations and prognosis. The use of new molecular, histological, and clinical criteria has improved their recognition. Cutaneous B-cell and T-cell lymphomas are seldom found together in the same patient. Here we report a rare case of mycosis fungoides variant of a cutaneous T-cell lymphoma (CTCL) which later developed Epstein-Barr virus (EBV) associated cutaneous B-cell lymphoproliferative disorder. The patient initially presented with generalized erythroderma, extensive plaques, and axillary lymphadenopathy. Histopathology and immunophenotyping of her tumor from the right breast nodule revealed a T-cell lymphoma consistent with mycosis fungoides. She was initially treated with pentostatin, followed by topical mechlorethamine and topical steroids. After progression of her mycosis fungoides with worsening diffuse skin lesions on this regimen, her treatments were changed to oral bexarotene with an initial partial response followed by stable disease. Three years from her initial presentation, she developed ulcerated cauliflower-like nodules on her forehead. Biopsy of these lesions revealed EBV-positive large- and medium-sized pleomorphic B-cells consistent with EBV-driven B-cell lymphoproliferative disorder. She was treated with topical acyclovir cream on the involved skin areas while continuing with oral bexarotene for mycosis fungoides. Skin lesions gradually diminished and totally disappeared after four weeks of topical acyclovir treatment. Bexarotene treatment was continued for another year until the mycosis fungoides progressed and became wide spread causing her death four and a half years after the initial diagnosis. The coexistence of two cutaneous non-Hodgkin lymphomas of different lineage in the same patient and the complete clinical response of EBV-related B-cell cutaneous component to topical acyclovir makes this rare case particularly interesting.

Acyclovir↗

PubMed2004

Prediction of survival in follicular lymphoma based on molecular features of tumor-infiltrating immune cells.

BACKGROUND: Patients with follicular lymphoma may survive for periods of less than 1 year to more than 20 years after diagnosis. We used gene-expression profiles of tumor-biopsy specimens obtained at diagnosis to develop a molecular predictor of the length of survival. METHODS: Gene-expression profiling was performed on 191 biopsy specimens obtained from patients with untreated follicular lymphoma. Supervised methods were used to discover expression patterns associated with the length of survival in a training set of 95 specimens. A molecular predictor of survival was constructed from these genes and validated in an independent test set of 96 specimens. RESULTS: Individual genes that predicted the length of survival were grouped into gene-expression signatures on the basis of their expression in the training set, and two such signatures were used to construct a survival predictor. The two signatures allowed patients with specimens in the test set to be divided into four quartiles with widely disparate median lengths of survival (13.6, 11.1, 10.8, and 3.9 years), independently of clinical prognostic variables. Flow cytometry showed that these signatures reflected gene expression by nonmalignant tumor-infiltrating immune cells. CONCLUSIONS: The length of survival among patients with follicular lymphoma correlates with the molecular features of nonmalignant immune cells present in the tumor at diagnosis.

Adult↗

PubMed2004

Distinct gene expression profiles in different B-cell compartments in human peripheral lymphoid organs.

BACKGROUND: There are three major B-cell compartments in peripheral lymphoid organs: the germinal center (GC), the mantle zone (MNZ) and the marginal zone (MGZ). Unique sets of B-cells reside in these compartments, and they have specific functional roles in humoral immune response. MNZ B cells are naive cells in a quiescent state and may participate in GC reactions upon proper stimulation. The adult splenic MGZ contains mostly memory B cells and is also known to provide a rapid response to particulate antigens. The GC B-cells proliferate rapidly and undergo selection and affinity maturation. The B-cell maturational process is accompanied by changes in the expression of cell-surface and intracellular proteins and requires signals from the specialized microenvironments. RESULTS: We performed laser microdissection of the three compartments for gene expression profiling by cDNA microarray. The transcriptional program of the GC was dominated by upregulation of genes associated with proliferation and DNA repair or recombination. The MNZ and MGZ showed increased expression of genes promoting cellular quiescence. The three compartments also revealed distinct repertoires of apoptosis-associated genes, chemokines and chemokine receptors. The MNZ and GC showed upregulation of CCL20 and CCL18 respectively. The MGZ was characterized by high expression of many chemokines genes e.g. CXCL12, CCL3, CCL14 and IFN-associated genes, consistent with its role in rapid response to infections. A stromal signature was identified including genes associated with macrophages or with synthesis of extracellular matrix and genes that influenced lymphocyte migration and survival. Differentially expressed genes that did not belong to the above categories include the well characterized BCL6 and CD10 and many others whose function is not known. CONCLUSIONS: Transcriptional profiling of B-cell compartments has identified groups of genes involved in critical molecular and cellular events that affect proliferation, survival migration, and differentiation of the cells. The gene expression study of normal B-cell compartments may additionally contribute to our understanding of the molecular abnormalities of the corresponding lymphoid tumors.

Apoptosis↗

PubMed2004

BCL2 protein expression parallels its mRNA level in normal and malignant B cells.

The regulation of B-cell lymphoma 2 (BCL2) protein expression in germinal center (GC) B cells has been controversial. Previous reports have indicated posttranscriptional regulation plays a dominant role. However, a number of recent studies contradicted these reports. Using real-time polymerase chain reaction (PCR) and Standardized Reverse Transcriptase-PCR (StaRT-PCR), we measured the level of mRNA expression in GC, mantle zone (MNZ), and marginal zone (MGZ) cells from laser capture microdissection. Both quantitative RT-PCR measurements of microdissected GC cells from tonsils showed that GC cells had low expression of BCL2 transcripts commensurate with the low protein expression level. These results are in agreement with microarray studies on fluorescence-activated cell sorter (FACS)-sorted cells and microdissected GC cells. We also examined BCL2 mRNA and protein expression on a series of 30 cases of diffuse large B-cell lymphoma (DLBCL) and found, in general, a good correlation. The results suggested that BCL2 protein expression is regulated at the transcriptional level in normal B cells and in the neoplastic cells in most B-cell lymphoproliferative disorders.

B-Lymphocytes↗

PubMed2004

Loss of MHC class II gene and protein expression in diffuse large B-cell lymphoma is related to decreased tumor immunosurveillance and poor patient survival regardless of other prognostic factors: a follow-up study from the Leukemia and Lymphoma Molecular Profiling Project.

The Leukemia and Lymphoma Molecular Profiling Project recently published results from DNA microarray analyses of 240 diffuse large B-cell lymphomas (DLBCLs). Four gene expression "signatures" were identified as correlated with patient outcome, including the major histocompatibility complex (MHC) class II genes (eg, HLA-DRA) which correlated with better survival. We further analyzed the effects of HLA-DRA on survival and correlated gene expression with protein status and tumor-infiltrating lymphocytes. The 5-year overall survival was 24% in the lowest 10% of HLA-DRA expression, 37% in the 10% to 25% group, 50% in the 25% to 50% group, and 55% for patients in the highest 50%. Further analysis demonstrated that the hazard ratio of death was a nonlinear function of HLA-DRA expression. Adjustment for the International Prognostic Index did not alter the impact of HLA-DRA on survival. Other MHC class II genes were found to predict survival similarly. Microarray HLA-DRA expression correlated with the presence or absence of human leukocyte antigen-DR (HLA-DR) protein in 20 of 22 cases assessed. Fewer tumor-infiltrating CD8(+) T cells were detected in MHC class II-negative cases compared with positive cases (2.8% versus 11.0%; P =.001), supporting the hypothesis that loss of tumor immunosurveillance has a devastating effect on patient outcome in DLBCL.

Follow-Up Studies↗

PubMed2004

Morphometric analysis of angiograms of exudative lesions in age-related macular degeneration.

OBJECTIVES: To analyze the morphometric composition of lesion components in exudative age-related macular degeneration and to study the relationships between individual lesion components and choroidal neovascularization (CNV) subtype, at 2 time points. METHODS: Morphometric analysis of 98 sets of angiograms separated by an interval of at least 3 weeks, with no treatment delivered in the intervening period between angiograms. Area measurements of individual lesion components were made from digitally captured angiograms. Choroidal neovascularizations were classified into subtypes based on the proportions of classic CNV. Fully corrected distance visual acuity measured on logMAR Early Treatment of Diabetic Retinopathy Study charts was available at baseline and at a subsequent visit in 78 subjects. Data were analyzed using parametric and nonparametric tests, linear regression, and McNemar test of equal proportions. RESULTS: Wholly and predominantly classic CNVs were significantly smaller at initial presentation than minimally classic or occult with no classic CNVs. Lesions containing blood and lipid were also significantly larger than lesions not exhibiting these features. Lesions containing any classic CNV expanded at a significantly greater rate than lesions without classic CNV. Approximately 40% of lesions categorized as wholly classic CNV converted to predominantly classic CNV between baseline and the next follow-up visit. CONCLUSION: The presence of classic leakage in exudative age-related macular degeneration is the most important risk factor for rapid expansion of CNV.

Capillary Permeability↗

PubMed2004

Cytogenetics and fluorescence in situ hybridization studies of diffuse large B-cell lymphoma in children and young adults.

Diffuse large B-cell lymphoma (DLBCL), the most common subtype of adult non-Hodgkin lymphoma (NHL), is infrequently seen in adolescents and is rare in children. Due to the infrequency of the disease, single institution-based cytogenetic and fluorescence in situ hybridization (FISH) studies of pediatric DLBCL have not been reported so far and, hence, the possible differences in pediatric and adult DLBCL have not been evaluated. We performed cytogenetic and FISH analyses of 7 pediatric and 5 young adult DLBCL cases referred to the University of Nebraska Medical Center. Karyotypic studies revealed numeric and structural chromosome abnormalities in all cases. Loss of chromosomes 2, 3, 4, 6, 12, 15, 16, and 17, and gain of 12, 18, and X were observed in more than 20% of the cases (#10878;3 cases). Sex chromosome abnormalities and cytogenetically unidentifiable chromosomes and/or segments were observed in 80% (10/12) of the cases. Recurrent breakpoints (observed in 3 or more cases) included 14q32 (IGH) and 17p13 (TP53), which clustered in the young adult group. The breakpoints 7q36, 9p24, 13q34, and 16q24 were noted in two cases each. We performed interphase FISH studies to verify the possible rearrangements of the breakpoints that are frequently implicated in adult DLBCL. Our results confirmed that the pediatric cases did not show rearrangements of 3q27 (BCL6), 14q32 (IGH), 18q21 (BCL2), 8q24 (CMYC), and 17p13 (TP53), except for one case with IGH;BCL2 dual fusion [t(14;18)(q32;q21)] and one with a 17p13 (TP53) deletion. Although 3q27 was noted to be rearranged by conventional cytogenetics in two young adult DLBCL cases, FISH investigations verified that BCL6 was not disrupted. The t(8;14)(q24;q32) with rearranged CMYC ascertained by FISH, was observed in a single young adult DLBCL case. These results highlight a distinctly different representation of cytogenetic abnormalities in pediatric versus adult DLBCL.

Adolescent↗

PubMed2004

BCL2 translocation defines a unique tumor subset within the germinal center B-cell-like diffuse large B-cell lymphoma.

Gene expression profiling of diffuse large B-cell lymphoma (DLBCL) has revealed prognostically important subgroups: germinal center B-cell-like (GCB) DLBCL, activated B cell-like (ABC) DLBCL, and primary mediastinal large B-cell lymphoma. The t(14;18)(q32;q21) has been reported previously to define a unique subset within the GCB-DLBCL. We evaluated for the translocation in 141 cases of DLBCL that were successfully gene expression profiled. Using a dual-probe fluorescence in situ hybridization assay, we detected the t(14;18) in 17% of DLBCLs and in 34% of the GCB subgroup which contained the vast majority of positive cases. In addition, 12 t(14;18)-positive cases detected by polymerase chain reaction assays on additional samples were added to the fluorescence in situ hybridization-positive cases for subsequent analysis. Immunohistochemical data indicated that BCL2, BCL6, and CD10 protein were preferentially expressed in the t(14;18)-positive cases as compared to t(14;18)-negative cases. Within the GCB subgroup, the expression of BCL2 and CD10, but not BCL6, differed significantly between cases with or without the t(14;18): 88% versus 24% for BCL2 and 72% versus 32% for CD10, respectively. In the GCB-DLBCL subgroup, a heterogeneous group of genes is overexpressed in the t(14;18)-positive subset, among which BCL2 is a significant discriminator. Interestingly, the t(14;18)-negative subset is dominated by overexpression of cell cycle-associated genes, indicating that these tumors are significantly more proliferative, suggesting distinctive pathogenetic mechanisms. However, despite this higher proliferative activity, there was no significant difference in overall or failure-free survival between the t(14;18)-positive and -negative subsets within the GCB subgroup.

Apoptosis Regulatory Proteins↗

PubMed2004

Diffuse large B-cell lymphoma arising in nodular lymphocyte predominant Hodgkin lymphoma: a report of 21 cases from the Nebraska Lymphoma Study Group.

We sought to investigate the clinical characteristics and pathologic features and survival outcome of patients with diffuse large B-cell lymphoma (DLBCL) arising in nodular lymphocyte predominant Hodgkin lymphoma (NLPHL), since controversy regarding their prognosis exists in the literature. Twenty-one patients with DLBCL arising either concurrently with (n = 7) or subsequent to (n = 14) a diagnosis of NLPHL were identified in the Nebraska Lymphoma Study Group Registry. The clinical and pathologic features of the cases were evaluated, and survival analysis was performed from the time of diagnosis of DLBCL. The median time to the development of DLBCL in those with prior NLPHL was only one year (range, 0.5-24 years). The median age of the patients at the time of diagnosis of DLBCL was 46 years (range, 18-72 years) and the male to female ratio was 17:4. Ten patients presented with nodal DLBCL only, 6 patients presented with both nodal and extranodal involvement, and 5 patients presented with only extranodal DLBCL. Eleven patients had limited stage (I/II) disease and 10 had advanced stage (III/IV) disease. The median overall survival (OS) and failure-free survival (FFS) of the entire group was 35 months and 11 months, respectively, and the predicted 5-year OS and FFS was 31% and 18%, respectively. There were no significant differences in the survival outcomes between patients with DLBCL arising in NLPHL and age- and sex- matched patients with de novo DLBCL. Our findings suggest that patients with DLBCL arising in NLPHL have a prognosis similar to those with de novo DLBCL and should be treated aggressively.

Adolescent↗

PubMed2004

An unusual case of composite lymphoma involving chronic lymphocytic leukemia follicular lymphoma and Hodgkin disease.

Composite lymphomas constitute the presence of two different types of non-Hodgkin lymphoma or Hodgkin and non-Hodgkin lymphoma at the same anatomic site. We report an unusual case of a 73-year-old woman who initially presented with a composite lymphoma of chronic lymphocytic leukemia (CLL) and follicular lymphoma. After 5 years of follow-up and intermittent treatment, she developed Hodgkin disease with diffuse liver involvement. Biopsy of the liver showed Reed-Sternberg cells with typical morphology and immunophenotype. While fluorescent in situ hybridization (FISH) analyses for t(14;18) were positive in the lymph node tissue with follicular lymphoma, we were unable to show the same in the liver biopsy specimen. Here, we describe the clinical, morphologic, immunophenotypic, and cytogenetic features of this unusual composite lymphoma case involving CLL and follicular lymphoma, with the subsequent development of a Hodgkin lymphoma.

Aged↗

PubMed2004

Algorithmic fusion of gene expression profiling for diffuse large B-cell lymphoma outcome prediction.

Many different methods and techniques have been investigated for the processing and analysis of microarray gene expression profiling datasets. It is noted that the accuracy and reliability of the results are often dependent on the measurement approaches applied, and no single measurement so far is guaranteed to generate a satisfactory result. In this paper, an algorithmic fusion approach is presented for extracting genes that are predictive to clinical outcomes (survival-fatal) of diffuse large B-cell lymphoma on a set of microarray data for gene expression profiling. The approach integrates a set of measurements from different aspects in terms of the discrepancy indications and merit expectations of the gene expression patterns with respect to the clinical outcomes. A combination of statistical and non-statistical criteria, continuous and discrete parameterizations, as well as model-based and modeless evaluations is applied in the approach. By integrating these measurements, a set of genes that are indicative to the clinical outcomes are better captured from the gene expression profiling dataset.

Algorithms↗

PubMed2004

Suitability of stratagene reference RNA for analysis of lymphoid tissues.

We evaluated a lymphoid RNA standard prepared in our laboratory for spotted microarrays against the Universal Human Reference standard from Stratagene. Our goal was to determine if the Stratagene standard, which contains only two lymphoid cell lines out of a pool of 10 human cancer cell lines, had acceptable gene coverage to serve as a comprehensive standard for gene expression profiling of lymphoid tissues. Our lymphoid standard was prepared from thymus, spleen, tonsil, and cell lines representing immature B cells, plasma cells, and natural killer (NK) cells, thus covering the entire spectrum of lymphoid cells and most stromal elements present in specialized lymphoid tissues. The two standards were co-hybridized on oligonucleotide microarrays containing 17,260 genes, and both had fluorescence intensities above background for approximately 85% of the genes. Despite the limited representation of lymphoid cells in the Stratagene standard, only 4.2% genes exhibited expression differences greater than 2-fold including only 0.35% with differences greater than 4-fold. Although the lymphoid standard reflected a more comprehensive representation of immune system-associated genes, the Stratagene standard has the advantage of being commercially available, enabling easier comparison across laboratories and allowing comparative studies across a long period of time.

Carbocyanines↗

PubMed2004

Molecular diagnosis and outcome prediction in diffuse large B-cell lymphoma and other subtypes of lymphoma.

Lymphoid malignancies are grouped and characterized by their morphology, immunophenotype, and genetic aberrations to help establish a diagnosis. Use of microarray technology enables the simultaneous determination of expression levels for thousands of genes, providing an additional powerful tool for improving disease classification. In this review, recent studies of diffuse large B-cell lymphoma (DLBCL), primary mediastinal large B-cell lymphoma, mantle cell lymphoma (MCL), and follicular lymphoma are highlighted, and the impact of gene expression profiling on the molecular diagnosis of these diseases is discussed. Based on microarray-generated gene expression profiles, outcome predictors were constructed for DLBCL and MCL. Specific expression patterns of a limited number of genes at the time of diagnosis were linked to overall survival in DLBCL and MCL. Such predictors of prognosis may eventually lead to risk-adjusted treatment of lymphomas. Specific therapeutic targets may also emerge with increased insight into the molecular features of the different lymphomas, thus illustrating the usefulness of gene expression profiling not only to improve diagnosis and classification but also to generate prognostic indicators and targets for therapy.

Humans↗

PubMed2004

Molecular diagnostics on lymphoid malignancies.

CONTEXT: Molecular diagnostics for lymphoid malignancies traditionally has focused on helping to provide a diagnosis on a tissue sample. The field has undergone substantial technical and conceptual evolution during the past 2 decades, and its role has expanded to new arenas, such as monitoring disease activities and detecting alterations in genes that are known to have a significant impact on disease outcome. OBJECTIVE: To review the advances in molecular diagnostics on lymphoid malignancies, including recent developments that may facilitate the development of mechanism-based diagnosis for individualized therapy. DESIGN: The development of molecular diagnostics in lymphoid malignancies is briefly reviewed with emphasis on the recent use of gene expression profiling for identifying important diagnostic and prognostic signatures. RESULTS: Genome-scale investigations are becoming technically feasible and have provided promising results in the identification of new disease entities and new, molecularly defined prognosticators. This development can potentially revolutionize diagnostic medicine in the near future. As new genes or genetic pathways that affect the clinical and biologic behavior of tumors are defined and can be readily assayed, molecular diagnostics will be expected to provide this relevant information. Ideally, therapy will be based on this information, delivering the most appropriate treatment with the least toxicity. CONCLUSIONS: Molecular diagnostics in the future will be moving toward a mechanism-based diagnosis for individualized therapy.

Humans↗

PubMed2003

Confirmation of the molecular classification of diffuse large B-cell lymphoma by immunohistochemistry using a tissue microarray.

Diffuse large B-cell lymphoma (DLBCL) can be divided into prognostically important subgroups with germinal center B-cell-like (GCB), activated B-cell-like (ABC), and type 3 gene expression profiles using a cDNA microarray. Tissue microarray (TMA) blocks were created from 152 cases of DLBCL, 142 of which had been successfully evaluated by cDNA microarray (75 GCB, 41 ABC, and 26 type 3). Sections were stained with antibodies to CD10, bcl-6, MUM1, FOXP1, cyclin D2, and bcl-2. Expression of bcl-6 (P <.001) or CD10 (P =.019) was associated with better overall survival (OS), whereas expression of MUM1 (P =.009) or cyclin D2 (P <.001) was associated with worse OS. Cases were subclassified using CD10, bcl-6, and MUM1 expression, and 64 cases (42%) were considered GCB and 88 cases (58%) non-GCB. The 5-year OS for the GCB group was 76% compared with only 34% for the non-GCB group (P <.001), which is similar to that reported using the cDNA microarray. Bcl-2 and cyclin D2 were adverse predictors in the non-GCB group. In multivariate analysis, a high International Prognostic Index score (3-5) and the non-GCB phenotype were independent adverse predictors (P <.0001). In summary, immunostains can be used to determine the GCB and non-GCB subtypes of DLBCL and predict survival similar to the cDNA microarray.

Adolescent↗