Biomedical subjects

Fenghuang Zhan

Publications and source records attributed to Fenghuang Zhan.

31 records · Page 2Linked to original sources

PubMed2004

Expression of PAX5 in CD20-positive multiple myeloma assessed by immunohistochemistry and oligonucleotide microarray.

Silencing of PAX5 gene by upregulation of B-lymphocyte-induced maturation protein-1 (PRDM1) is essential for terminal differentiation of B cells to plasma cells. To investigate PAX5 gene expression and its protein product, B-cell-specific activator protein (BSAP), in a subgroup of multiple myeloma characterized by CD20 expression, we studied PAX5/BSAP by immunohistochemistry in 25 cases of myeloma, all expressing moderate to strong CD20 by flow cytometric analysis, and correlated the results with PAX5 and PRDM1 mRNA levels analyzed by the Affymetrix HuGeneFL GeneChip microarray in 17 cases. Using paraffin-embedded bone marrow biopsy sections, we found PAX5/BSAP was expressed in 72% (18/25) of cases overall with an intensity ranging from weak (10, 56%) to strong (8, 44%). PAX5/BSAP was negative in 10 randomly selected CD20-negative myelomas included as negative controls. PAX5 mRNA levels correlated inversely with that of PRDM1 in both CD20-positive and CD20-negative myelomas and failed to predict the expression levels of PAX5/BSAP, suggesting that detected PAX5/BSAP likely represents remnant of earlier stage of development. We conclude that CD20-positive myelomas expressing PAX5/BSAP can present as a diagnostic pitfall mimicking B-cell neoplasms with plasmacytoid differentiation.

Adult↗

PubMed2003

The role of the Wnt-signaling antagonist DKK1 in the development of osteolytic lesions in multiple myeloma.

BACKGROUND: Myeloma cells may secrete factors that affect the function of osteoblasts, osteoclasts, or both. METHODS: We subjected purified plasma cells from the bone marrow of patients with newly diagnosed multiple myeloma and control subjects to oligonucleotide microarray profiling and biochemical and immunohistochemical analyses to identify molecular determinants of osteolytic lesions. RESULTS: We studied 45 control subjects, 36 patients with multiple myeloma in whom focal lesions of bone could not be detected by magnetic resonance imaging (MRI), and 137 patients in whom MRI detected such lesions. Different patterns of expression of 57 of approximately 10,000 genes from purified myeloma cells could be used to distinguish the two groups of patients (P<0.001). Permutation analysis, which adjusts the significance level to account for multiple comparisons in the data sets, showed that 4 of these 57 genes were significantly overexpressed by plasma cells from patients with focal lesions. One of these genes, dickkopf 1 (DKK1), and its corresponding protein (DKK1) were studied in detail because DKK1 is a secreted factor that has been linked to the function of osteoblasts. Immunohistochemical analysis of bone marrow-biopsy specimens showed that only myeloma cells contained detectable DKK1. Elevated DKK1 levels in bone marrow plasma and peripheral blood from patients with multiple myeloma correlated with the gene-expression patterns of DKK1 and were associated with the presence of focal bone lesions. Recombinant human DKK1 or bone marrow serum containing an elevated level of DKK1 inhibited the differentiation of osteoblast precursor cells in vitro. CONCLUSIONS: The production of DKK1, an inhibitor of osteoblast differentiation, by myeloma cells is associated with the presence of lytic bone lesions in patients with multiple myeloma.

Bone Marrow↗

PubMed2003

High heparanase activity in multiple myeloma is associated with elevated microvessel density.

Heparanase is an enzyme that cleaves heparan sulfate chains of proteoglycans, and its expression has been associated with increased growth, metastasis, and angiogenesis of some tumors. Because myeloma tumor cells express high levels of the syndecan-1 heparan sulfate proteoglycan and because these tumors grow as highly vascularized aggregates within the bone marrow, we analyzed the activity, expression, and function of heparanase in myeloma patients. Analysis of heparanase activity in the plasma isolated from bone marrow biopsies of 100 patients reveals 86 positive for heparanase activity and 14 negative. The bone marrow samples can be further divided into three categories of heparanase activity, high activity (42 patients), low activity (44 patients), and negative (14 patients). In contrast to the bone marrow plasma, levels of heparanase activity in peripheral blood plasma of 29 myeloma patients were either negative or low, suggesting that in multiple myeloma, heparanase functions in the local microenvironment of the bone marrow and its activity is not significantly elevated systemically. Immunohistochemistry reveals that patients with high levels of heparanase activity often have tumor cells with intense staining for the enzyme. Interestingly, a marked heterogeneity among tumor cells was noted, with clusters of heavily stained cells surrounded by cells with weak or negative staining for heparanase. Analysis of microvessel density reveals a strikingly higher concentration of vessels in patients with high heparanase activity (78.96 vessels/mm(2)) as compared with patients negative for heparanase activity (25.03 vessels/mm(2)). When human myeloma cells transfected with the cDNA for heparanase are implanted in severe combined immunodeficient (SCID) mice, the resulting tumors exhibited a significantly higher microvessel density than did tumors established with control cells. Thus, expression of heparanase appears to play a direct role in enhancing microvessel density in these myeloma tumors. Because heparanase is known to stimulate angiogenesis, and because high microvessel density is associated with poor prognosis in myeloma, we conclude that heparanase expression likely plays an important role in regulating the growth and progression of myeloma, and that therapies designed to block heparanase activity may aid in controlling this cancer.

Animals↗

PubMed2003

Gene expression profiling of plasma cells and plasmablasts: toward a better understanding of the late stages of B-cell differentiation.

Plasma cells (PCs), the end point of B-cell differentiation, are a heterogeneous cell compartment comprising several cell subsets from short-lived highly proliferative plasmablasts to long-lived nondividing fully mature PCs. Whereas the major transcription factors driving the differentiation of B cells to PCs were recently identified, the subtle genetic changes that underlie the transition from plasmablasts to mature PCs are poorly understood. We recently described an in vitro model making it possible to obtain a large number of cells with the morphologic, phenotypic, and functional characteristics of normal polyclonal plasmablastic cells (PPCs). Using Affymetrix microarrays we compared the gene expression profiles of these PPCs with those of mature PCs isolated from tonsils (TPCs) and bone marrow (BMPCs), and with those of B cells purified from peripheral blood (PBB cells) and tonsils (TBCs). Unsupervised principal component analysis clearly distinguished the 5 cell populations on the basis of their differentiation and proliferation status. Detailed statistical analysis allowed the identification of 85 PC genes and 40 B-cell genes, overexpressed, respectively, in the 3 PC subsets or in the 2 B-cell subsets. In addition, several signaling molecules and antiapoptotic proteins were found to be induced in BMPCs compared with PPCs and could be involved in the accumulation and prolonged survival of BMPCs in close contact with specialized stromal microenvironment. These data should help to better understand the molecular events that regulate commitment to a PC fate, mediate PC maintenance in survival niches, and could facilitate PC immortalization in plasma cell dyscrasias.

Autocrine Communication↗

PubMed2003

Continuous absence of metaphase-defined cytogenetic abnormalities, especially of chromosome 13 and hypodiploidy, ensures long-term survival in multiple myeloma treated with Total Therapy I: interpretation in the context of global gene expression.

Metaphase cytogenetic abnormalities (CAs), especially of chromosome 13 (CA 13), confer a grave prognosis in multiple myeloma even with tandem autotransplantations as applied in Total Therapy I, which enrolled 231 patients between 1989 and 1994. With a median follow-up of almost 9 years, the prognostic implications of all individual CAs, detected prior to treatment and at relapse, were investigated. Among all CAs and standard prognostic factors examined prior to therapy, only hypodiploidy and CA 13 (hypo-13 CA), alone or in combination, were associated with shortest event-free survival and overall survival (OS). The shortest postrelapse OS was observed with hypo-13 CA, which was newly detected in 18 of all 28 patients presenting with this abnormality at relapse. Superior prognosis was associated with the absence of any CA at both diagnosis and relapse (10-year OS, 40%). The lack of independent prognostic implications of other CAs points to a uniquely aggressive behavior of hypo-13 CA (present in 16% of patients at diagnosis). With the use of microarray data in 146 patients enrolled in Total Therapy II, overexpression of cell cycle genes distinguished CA from no CA, especially in cases of del(13) detected by interphase fluorescence in situ hybridization (FISH). FISH 13, resulting in a haploinsufficiency of RB1 and other genes mapping to chromosome 13, as well as activation of IGF1R, appears to have an amplifying effect on cell cycle gene expression, thus providing a molecular explanation for the dire outcome of patients with CA 13 compared with those with other CAs.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2003

Toward the identification of distinct molecular and clinical entities of multiple myeloma using global gene expression profiling.

Multiple myeloma (MM) is a poorly understood and uniformly fatal malignancy of antibody-secreting plasma cells (PC). Although several key molecular events in disease initiation or progression have been confirmed (such as 14q32 translocations) or implicated (chromosome 13 deletion), a unifying mechanism of myelomagenesis has proved elusive. Furthermore, while MM is generally indistinguishable morphologically, the disease exhibits tremendous variability in its clinical course, with some patients surviving only months and others many years, suggesting that MM is composed of distinct clinical entities. As abnormal gene expression is central to most, if not all cancers, high-throughput global gene expression profiling has become a powerful tool to investigate the molecular biology and clinical behavior of malignancy. Here we discuss recent progress made in the development of molecular-based diagnostics and prognostics for MM through the dissection of the transcriptome of PCs from healthy individuals and patients with MM and other PC dyscrasias.

Cell Differentiation↗

PubMed2003

The distinct gene expression profiles of chronic lymphocytic leukemia and multiple myeloma suggest different anti-apoptotic mechanisms but predict only some differences in phenotype.

We compared gene expression in purified tumor cells from untreated patients with chronic lymphocytic (CLL) (n=24) and newly diagnosed multiple myeloma (MM) (n=29) using the Affymetrix HuGeneFL microarray with probes for approximately 6800 genes. Hierarchical clustering analysis showed that CLL and MM have distinct expression profiles (class prediction). Gene and protein expression (measured by flow cytometry) correlated well for CD19, CD20, CD23, and CD138 in CLL and MM, but not for immunoglobulin light chain, CD38 and CD79b in CLL, or CD45 and CD52 in MM. CLL and MM differentially expressed 18% of 130 apoptosis related genes, suggesting differences in mechanisms of cell survival.

Antigens, CD↗

PubMed2003

CD27 is heterogeneously expressed in multiple myeloma: low CD27 expression in patients with high-risk disease.

Expression of CD27 on malignant plasma cells (PC) (CD138+CD38++) was analysed in a cross-sectional study of bone marrow (BM) samples from multiple myeloma (MM) patients (n = 28), monoclonal gammopathy of undetermined significance (MGUS) patients (n = 6) and BM PC from healthy donors (n = 4). MM PC expressed CD27 with a variable, lower intensity pattern compared with the consistent high expression in MGUS and healthy donors. MM patients in complete clinical remission displayed a higher percentage of CD27+ PC compared with patients at diagnosis, relapse or in partial remission. In MM, loss of CD27 correlated with loss of CD19 (R2 = 0.4, P < 0.0001). Human MM cell lines (n = 9) did not express CD27 whereas de novo plasma cell leukaemia (PCL) (n = 3) had a high expression. Re-analysis of a cDNA microarray data set, generated from newly diagnosed MM patients (n = 74), demonstrated that the MM subgroup with the highest prevalence of poor prognostic factors had the lowest CD27 mRNA expression. Fluorescence-activated cell sorting and allele-specific oligonucleotide polymerase chain reaction showed that both CD27+ and CD27- PC subpopulations in MM can belong to the clonal disorder. In conclusion, CD27 is heterogeneously expressed on MM PC and loss of CD27 expression might have prognostic value in MM.

ADP-ribosyl Cyclase↗

PubMed2002

A subset of multiple myeloma harboring the t(4;14)(p16;q32) translocation lacks FGFR3 expression but maintains an IGH/MMSET fusion transcript.

Previous studies have revealed that that approximately 10% to 15% of multiple myelomas (MMs) are characterized by a reciprocal t(4;14)(p16;q32) translocation that activates expression of FGFR3 and creates an IGH/MMSET fusion transcript. Current data suggest that activation of FGFR3 is the oncogenic consequence of this rearrangement. Using a combination of microarray profiling, reverse transcriptase-polymerase chain reaction (RT-PCR), and interphase fluorescence in situ hybridization (FISH), we show that 32 (18%) of 178 newly diagnosed cases of MM harbor the t(4;14)(p16;q32). Importantly, 32% of these cases lack expression of FGFR3, yet express MMSET and have an IGH/MMSET fusion transcript. Interphase FISH showed that whereas the IGH/MMSET fusion was present in more than 80% of the clonotypic plasma cells in these novel cases, there was typically a complete loss of one copy of FGFR3. These data indicate that the t(4;14)(p16;q32) and loss of FGFR3 occurred at a very early stage and suggest that activation of MMSET, not FGFR3, may be the critical transforming event of this recurrent translocation.

Bone Marrow↗

PubMed2002

Gene expression profiling of human plasma cell differentiation and classification of multiple myeloma based on similarities to distinct stages of late-stage B-cell development.

To identify genes linked to normal plasma cell (PC) differentiation and to classify multiple myeloma (MM) with respect to the expression patterns of these genes, we analyzed global mRNA expression in CD19-enriched B cells (BCs) from 7 tonsils, CD138-enriched PCs from 11 tonsils, 31 normal bone marrow samples, and 74 MM bone marrow samples using microarrays interrogating 6800 genes. Hierarchical clustering analyses with 3288 genes clearly segregated the 4 cell types, and chi-square and Wilcoxin rank sum tests (P <.0005) identified 359 and 500 previously defined and novel genes that distinguish tonsil BCs from tonsil PCs (early differentiation genes [EDGs]), and tonsil PCs from bone marrow PCs (late differentiation genes [LDGs]), respectively. MM as a whole was found to have dramatically variable expression of EDGs and LDGs, and one-way analysis of variance (ANOVA) was used to identify the most variable EDGs (vEDGs) and LDGs (v1LDG and v2LDG). Hierarchical cluster analysis with these genes revealed that previously defined MM gene expression subgroups (MM1-MM4) could be linked to one of the 3 normal cell types. Clustering with 30 vEDGs revealed that 13 of 18 MM4 cases clustered with tonsil BCs (P =.000 05), whereas 14 of 15 MM3 cases clustered with tonsil PCs when using 50 v1LDG (P =.000 008), and 14 of 20 MM2 cases clustered with bone marrow PCs when using 50 v2LDG (P =.000 09). MM1 showed no significant linkage with normal cell types studied. Thus, genes whose expression is linked to distinct transitions in late-stage B-cell differentiation can be used to classify MM.

Antigens, CD19↗

PubMed2002

Generation of polyclonal plasmablasts from peripheral blood B cells: a normal counterpart of malignant plasmablasts.

A new way to identify tumor-specific genes is to compare gene expression profiles between malignant cells and their autologous normal counterparts. In patients with multiple myeloma, a major plasma cell disorder, normal plasma cells are not easily attainable in vivo. We report here that in vitro differentiation of peripheral blood B lymphocytes, purified from healthy donors and from patients with multiple myeloma, makes it possible to obtain a homogeneous population of normal plasmablastic cells. These cells were identified by their morphology, phenotype, production of polyclonal immunoglobulins, and expression of major transcription factors involved in B-cell differentiation. Oligonucleotide microarray analysis shows that these polyclonal plasmablastic cells have a gene expression pattern close to that of normal bone marrow-derived plasma cells. Detailed analysis of genes statistically differentially expressed between normal and tumor plasma cells allows the identification of myeloma-specific genes, including oncogenes and genes coding for tumor antigens. These data should help to disclose the molecular mechanisms of myeloma pathogenesis and to define new therapeutic targets in this still fatal malignancy. In addition, the comparison of gene expression between plasmablastic cells and B cells provides a new and powerful tool to identify genes specifically involved in normal plasma cell differentiation.

ADP-ribosyl Cyclase↗

PubMed2002

Global gene expression profiling of multiple myeloma, monoclonal gammopathy of undetermined significance, and normal bone marrow plasma cells.

Bone marrow plasma cells (PCs) from 74 patients with newly diagnosed multiple myeloma (MM), 5 with monoclonal gammopathy of undetermined significance (MGUS), and 31 healthy volunteers (normal PCs) were purified by CD138(+) selection. Gene expression of purified PCs and 7 MM cell lines were profiled using high-density oligonucleotide microarrays interrogating about 6800 genes. On hierarchical clustering analysis, normal and MM PCs were differentiated and 4 distinct subgroups of MM (MM1, MM2, MM3, and MM4) were identified. The expression pattern of MM1 was similar to normal PCs and MGUS, whereas MM4 was similar to MM cell lines. Clinical parameters linked to poor prognosis, abnormal karyotype (P =.002) and high serum beta(2)-microglobulin levels (P =.0005), were most prevalent in MM4. Also, genes involved in DNA metabolism and cell cycle control were overexpressed in a comparison of MM1 and MM4. In addition, using chi(2) and Wilcoxon rank sum tests, 120 novel candidate disease genes were identified that discriminate normal and malignant PCs (P <.0001); many are involved in adhesion, apoptosis, cell cycle, drug resistance, growth arrest, oncogenesis, signaling, and transcription. A total of 156 genes, including FGFR3 and CCND1, exhibited highly elevated ("spiked") expression in at least 4 of the 74 MM cases (range, 4-25 spikes). Elevated expression of these 2 genes was caused by the translocation t(4;14)(p16;q32) or t(11;14)(q13;q32). Thus, novel candidate MM disease genes have been identified using gene expression profiling and this profiling has led to the development of a gene-based classification system for MM.

Bone Marrow Cells↗

PubMed2002

CGO: utilizing and integrating gene expression microarray data in clinical research and data management.

Clinical GeneOrganizer (CGO) is a novel windows-based archiving, organization and data mining software for the integration of gene expression profiling in clinical medicine. The program implements various user-friendly tools and extracts data for further statistical analysis. This software was written for Affymetrix GeneChip *.txt files, but can also be used for any other microarray-derived data. The MS-SQL server version acts as a data mart and links microarray data with clinical parameters of any other existing database and therefore represents a valuable tool for combining gene expression analysis and clinical disease characteristics.

Computational Biology↗