Search tips
Search criteria

Results 1-25 (1634471)

Clipboard (0)

Related Articles

1.  Many Multiple Myelomas: Making More of the Molecular Mayhem 
Multiple myeloma (MM) is malignancy of isotype-switched, BM-localized plasma cells that frequently results in bone destruction, BM failure, and death. Important molecular subgroups are identified by three classes of recurrent immunoglobulin gene translocations and hyperdiploidy, both of which affect disease course. From a clinical standpoint, it is critical to identify MM patients carrying the t(4;14) translocation, which is present in 15% of myelomas and is associated with dysregulation of WHSC1/MMSET and often FGFR3. These patients should all receive bortezomib as part of their initial induction treatment because this has been shown to significantly prolong survival. In contrast, patients with translocations affecting the MAF family of transcription factors, del17p, or gene-expression profiling (GEP)–defined high-risk disease appear to have a worse prognosis that is not dramatically improved by any intervention. These patients should be enrolled in innovative clinical trials. The remaining patients with cyclin D translocations or hyperdiploidy do well with most therapies, and the goal should be to control disease while minimizing toxicity.
PMCID: PMC3903307  PMID: 22160056
2.  Frequent translocation t(4;14)(p16.3;q32.3) in multiple myeloma is associated with increased expression and activating mutations of fibroblast growth factor receptor 3 
Nature genetics  1997;16(3):260-264.
Dysregulation of oncogenes by translocation to the IgH locus (14q32) is a seminal event in the pathogenesis of B-cell tumours1. In multiple myeloma (MM), translocations to the IgH locus have been reported at an incidence of 20–60%. For most translocations, the partner chromosome is unknown (14q+); for the others, a diverse array of chromosomal partners have been identified, with 11q13 (cyclin D1) the only chromosome that is frequently involved2–6. Recently, we developed a Southern-blot assay that detects translocation breakpoint fragments in most MM tumours, including those with no translocation detected by conventional karyotyping6. In a continuing analysis of translocations in 21 myeloma cell lines and primary tumours, we show that the novel, karyotypically silent translocation t(4;14)(p16.3;q32.3) is present in five lines and at least three of ten primary tumours. The chromosome-4 breakpoints are clustered in a 70-kb region centromeric to the fibroblast growth factor receptor 3 gene (FGFR3), the apparent dysregulated oncogene. Two lines and one primary tumour with this translocation selectively express an FGFR3 allele containing activating mutations identified previously in thanatophoric dwarfism. We propose that after the t(4;14) translocation, somatic mutation during tumour progression frequently generates an FGFR3 protein that is active in the absence of ligand.
PMCID: PMC3901950  PMID: 9207791
3.  Ectopic expression of wild-type FGFR3 cooperates with MYC to accelerate development of B-cell lineage neoplasms 
Leukemia  2010;24(6):1171-1178.
The t(4;14) translocation in multiple myeloma (MM) simultaneously dysregulates two apparent oncogenes: fibroblast growth factor receptor 3 (FGFR3) controlled by the 3′ immunoglobulin heavy chain enhancer on der(14) and MMSET controlled by the intronic Eμ enhancer on der(4). Although all MM tumors and cell lines with a t(4;14) translocation have dysregulated MMSET, about 25% do not express FGFR3. Therefore, the function of dysregulated wild-type (WT) FGFR3 in the pathogenesis of MM remains unclear. We developed a murine transgenic (TG) model in which WT FGFR3 is over-expressed in B lymphoid cells. Although high levels of FGFR3 resulted in lymphoid hyperplasia in about one-third of older mice, no increase in tumorigenesis was observed. However, double TG FGFR3/Myc mice develop mature B lymphoma tumors that occur with a higher penetrance and shorter latency than in single TG Myc mice (P = 0.006). We conclude that expression of high levels of WT FGFR3 can be oncogenic and cooperate with MYC to generate B lymphoid tumors. This suggests that dysregulated FGFR3 expression is likely to be essential at least for the early stages of pathogenesis of MM tumors that have a t(4;14) translocation.
PMCID: PMC3118571  PMID: 20393505
FGFR3; Myc; lymphoma; multiple myeloma; oncogene
4.  Integrated Genomic Characterization Reveals Novel, Therapeutically Relevant Drug Targets in FGFR and EGFR Pathways in Sporadic Intrahepatic Cholangiocarcinoma 
PLoS Genetics  2014;10(2):e1004135.
Advanced cholangiocarcinoma continues to harbor a difficult prognosis and therapeutic options have been limited. During the course of a clinical trial of whole genomic sequencing seeking druggable targets, we examined six patients with advanced cholangiocarcinoma. Integrated genome-wide and whole transcriptome sequence analyses were performed on tumors from six patients with advanced, sporadic intrahepatic cholangiocarcinoma (SIC) to identify potential therapeutically actionable events. Among the somatic events captured in our analysis, we uncovered two novel therapeutically relevant genomic contexts that when acted upon, resulted in preliminary evidence of anti-tumor activity. Genome-wide structural analysis of sequence data revealed recurrent translocation events involving the FGFR2 locus in three of six assessed patients. These observations and supporting evidence triggered the use of FGFR inhibitors in these patients. In one example, preliminary anti-tumor activity of pazopanib (in vitro FGFR2 IC50≈350 nM) was noted in a patient with an FGFR2-TACC3 fusion. After progression on pazopanib, the same patient also had stable disease on ponatinib, a pan-FGFR inhibitor (in vitro, FGFR2 IC50≈8 nM). In an independent non-FGFR2 translocation patient, exome and transcriptome analysis revealed an allele specific somatic nonsense mutation (E384X) in ERRFI1, a direct negative regulator of EGFR activation. Rapid and robust disease regression was noted in this ERRFI1 inactivated tumor when treated with erlotinib, an EGFR kinase inhibitor. FGFR2 fusions and ERRFI mutations may represent novel targets in sporadic intrahepatic cholangiocarcinoma and trials should be characterized in larger cohorts of patients with these aberrations.
Author Summary
Cholangiocarcinoma is a cancer that affects the bile ducts. Unfortunately, many patients diagnosed with cholangiocarcinoma have disease that cannot be treated with surgery or has spread to other parts of the body, thus severely limiting treatment options. New advances in drug treatment have enabled treatment of these cancers with “targeted therapy” that exploits an error in the normal functioning of a tumor cell, compared to other cells in the body, thus allowing only tumor cells to be killed by the drug. We sought to identify changes in the genetic material of cholangiocarcinoma patient tumors in order to identify potential errors in cellular functioning by utilizing cutting edge genetic sequencing technology. We identified three patient tumors possessing an FGFR2 gene that was aberrantly fused to another gene. Two of these patients were able to receive targeted therapy for FGFR2 with resulting tumor shrinkage. A fourth tumor contained an error in a gene that controls a very important cellular mechanism in cancer, termed epidermal growth factor pathway (EGFR). This patient received therapy targeting this mechanism and also demonstrated response to treatment. Thus, we have been able to utilize cutting edge technology with targeted drug treatment to personalize medical treatment for cancer in cholangiocarcinoma patients.
PMCID: PMC3923676  PMID: 24550739
5.  Rationale for targeting fibroblast growth factor receptor signaling in breast cancer 
Fibroblast growth factor receptor (FGFR) signaling is involved in multiple biological processes, including cell proliferation, survival, differentiation, migration, and apoptosis during embryonic development and adult tissue homeostasis. Given its role in the activation of critical signaling pathways, aberrant FGFR signaling has been implicated in multiple cancer types. A comprehensive search of PubMed and congress abstracts was conducted to identify reports on FGFR pathway components in breast cancer. In breast cancers, FGFR1 and FGFR4 gene amplification and single nucleotide polymorphisms in FGFR2 and FGFR4 have been detected. Commonly, these FGFR aberrations and gene amplifications lead to increased FGFR signaling and have been linked with poor prognosis and resistance to breast cancer treatments. Here, we review the role of FGFR signaling and the impact of FGFR genetic amplifications/aberrations on breast tumors. In addition, we summarize the most recent preclinical and clinical data on FGFR-targeted therapies in breast cancer. Finally, we highlight the ongoing clinical trials of the FGFR-targeted agents dovitinib, AZD4547, lucitanib, BGJ398, and JNJ-42756493, which are selected for patients with FGFR pathway-amplified breast cancer. Aberrant FGFR pathway amplification may drive some breast cancers. Inhibition of FGFR signaling is being explored in the clinic, and data from these trials may refine our ability to select patients who would best respond to these treatments.
PMCID: PMC4344551  PMID: 25677745
Breast cancer; Fibroblast growth factor receptor; FGFR; FGFR pathway amplification; FGFR genetic aberrations
Neuro-Oncology  2014;16(Suppl 2):ii26-ii27.
Glioblastoma growth is driven by receptor tyrosine kinase (RTK)-mediated signals. One of the RTK systems recently coming into focus are the fibroblast growth factor (FGF) high-affinity receptors (FGFR1-FGFR4) due to mutation, overexpression or translocation in several cancer types. FGF/FGFR represents a complex signal network with essential functions in embryonic development, tissue homeostasis and wound healing but also for malignant transformation and growth as well as tumor neoangiogenesis and therapy failure. Several studies have suggested a role of FGFRs in human glioblastoma whereby the information on FGFR4 is sparse. Here we investigated whether FGFR4 as compared to FGFR1 blockade impacts on glioblastoma growth in vitro and in vivo. Both in human glioblastoma cell lines (N = 8) and primary cell cultures from clinical samples (N = 26) we found a widespread expression of several FGFs (e.g. FGF1, FGF2, and FGF5) but also a significant overexpression of FGFR1 and FGFR4 in distinct subgroups as compared to non-malignant brain primo cell cultures. Regarding FGFR1 mRNA, all glioma cell models investigated expressed in addition to the FGFR1-IIIb also the mesenchymal and more oncogenic FGFR1-IIIc splice variant. Application of the FGFR inhibitors (nintedanib, ponatinib) as well as expression of dominant-negative (dn) versions of FGFR1 and FGFR4 significantly reduced in vitro cell growth and clonogenicity in the tested glioma cell models whereby dnFGFR1 tended to be more efficient than dnFGFR4. Accordingly, both dominant-negative FGFRs induced significant apoptosis whereby the effects of dnFGFR1 were again significantly stronger. Surprisingly, the inhibitory effects on anchorage-independent growth in soft agar were opposite with significant mitigation by dnFGFR1 but almost complete blockade by dnFGFR4 in the majority of the glioblastoma models analysed. Additionally, neurosphere formation, indicative for the presence of glioma stem cells, was profoundly reduced by both dnFGFRs. Interestingly, FGFR4 belonged to those genes significantly overexpressed in the cancer stem cell compartment (N = 16; mRNA expression arrays of neurosphere versus adherent cell culture). Accordingly, growth of two out of three human glioblastoma xenografts analysed in SCID mice was completely inhibited by dnFGFR4 while only retarded by dnFGFR1. Summarizing our data substantiates a significant contribution of FGF/FGFR-mediated signals to different aspects of glioblastoma aggressiveness and suggests a particular role of FGFR4 in stemness and three-dimensional in vivo growth.
PMCID: PMC4185867
7.  Genomic aberrations in the FGFR pathway: opportunities for targeted therapies in solid tumors 
Annals of Oncology  2013;25(3):552-563.
The fibroblast growth factor receptor (FGFR) cascade plays crucial roles in tumor cell proliferation, angiogenesis, migration and survival. Accumulating evidence suggests that in some tumor types, FGFRs are bona fide oncogenes to which cancer cells are addicted. Because FGFR inhibition can reduce proliferation and induce cell death in a variety of in vitro and in vivo tumor models harboring FGFR aberrations, a growing number of research groups have selected FGFRs as targets for anticancer drug development. Multikinase FGFR/vascular endothelial growth factor receptor (VEGFR) inhibitors have shown promising activity in breast cancer patients with FGFR1 and/or FGF3 amplification. Early clinical trials with selective FGFR inhibitors, which may overcome the toxicity constraints raised by multitarget kinase inhibition, are recruiting patients with known FGFR(1–4) status based on genomic screens. Preliminary signs of antitumor activity have been demonstrated in some tumor types, including squamous cell lung carcinomas. Rational combination of targeted therapies is expected to further increase the efficacy of selective FGFR inhibitors. Herein, we discuss unsolved questions in the clinical development of these agents and suggest guidelines for management of hyperphosphatemia, a class-specific mechanism-based toxicity. In addition, we propose standardized definitions for FGFR1 and FGFR2 gene amplification based on in situ hybridization methods. Extended access to next-generation sequencing platforms will facilitate the identification of diseases in which somatic FGFR(1–4) mutations, amplifications and fusions are potentially driving cancer cell viability, further strengthening the role of FGFR signaling in cancer biology and providing more possibilities for the therapeutic application of FGFR inhibitors.
PMCID: PMC4433501  PMID: 24265351
fibroblast growth factor receptor FGFR; amplification; cancer; hyperphosphatemia; oncogene; targeted therapy
8.  Detection, characterization and inhibition of FGFR-TACC fusions in IDH wild type glioma 
Oncogenic fusions consisting of FGFR and TACC are present in a subgroup of glioblastoma (GBM) and other human cancers and have been proposed as new therapeutic targets. We analyzed frequency, molecular features of FGFR-TACC fusions, and explored the therapeutic efficacy of inhibiting FGFR kinase in GBM and grade-II–III glioma.
Experimental Design
Overall, 795 gliomas (584 GBM, 85 grade-II–III with wild-type and 126 with IDH1/2 mutation) were screened for FGFR-TACC breakpoints and associated molecular profile. We also analyzed expression of the FGFR3 and TACC3 components of the fusions. The effects of the specific FGFR inhibitor JNJ-42756493 for FGFR3-TACC3-positive glioma were determined in preclinical experiments. Two patients with advanced FGFR3-TACC3-positive GBM received JNJ-42756493 and were assessed for therapeutic response.
Three of 85 IDH1/2 wild type (3.5%) but none of 126 IDH1/2 mutant grade-II–III glioma harbored FGFR3-TACC3 fusions. FGFR-TACC rearrangements were present in 17 of 584 GBM (2.9%). FGFR3-TACC3 fusions were associated with strong and homogeneous FGFR3 immunostaining. They are mutually exclusive with IDH1/2 mutations and EGFR amplification whereas co-occur with CDK4 amplification. JNJ-42756493 inhibited growth of glioma cells harboring FGFR3-TACC3 in vitro and in vivo. The two patients with FGFR3-TACC3 rearrangements who received JNJ-42756493 manifested clinical improvement with stable disease and minor response, respectively.
RT-PCR-sequencing is a sensitive and specific method to identify FGFR-TACC-positive patients. FGFR3-TACC3 fusions are associated with uniform intra-tumor expression of the fusion protein. The clinical response observed in the FGFR3-TACC3-positive patients treated with a FGFR inhibitor supports clinical studies of FGFR inhibition in FGFR-TACC-positive patients.
PMCID: PMC4506218  PMID: 25609060
glioma; FGFR3-TACC3 fusion; IDH wild type; target therapy
9.  Molecular pathogenesis of multiple myeloma: basic and clinical updates 
Multiple myeloma is divided into two distinct genetic subtypes based on chromosome content. Hyperdiploid myeloma is characterized by multiple trisomies of chromosomes 3, 5, 7, 9 11, 15, 19 and 21, and lacks recurrent immunoglobulin gene translocations. Non-hyperdiploid myeloma in contrast is characterized by chromosome translocations t(4;14), t(14;16), t(14;20), t(6;14) and t(11;14). A unifying event in the pathogenesis of multiple myeloma is the dysregulated expression of a cyclin D gene, either directly by juxtaposition to an immunoglobulin enhancer, as a result of ectopic expression of a MAF family transcription factor, or indirectly by as yet unidentified mechanisms. Secondary genetic events include rearrangements of MYC, activating mutations of NRAS, KRAS or BRAF, a promiscuous array of mutations that activate NFkB and deletions of 17p. Among the poor-risk genetic features are t(4;14), t(14;16), t(14;20), del 17p and gains of 1q. Available evidence supports the use of a risk-stratified approach to the treatment of patients with multiple myeloma, with the early and prolonged use of bortezomib particularly in patients with t(4;14) and del 17p.
PMCID: PMC3962846  PMID: 23456262
Pathogenesis; Multiple myeloma; Genetics; Prognosis; Treatment
10.  Antibody-based targeting of FGFR3 in bladder carcinoma and t(4;14)-positive multiple myeloma in mice 
The Journal of Clinical Investigation  2009;119(5):1216-1229.
Overexpression of FGF receptor 3 (FGFR3) is implicated in the development of t(4;14)-positive multiple myeloma. While FGFR3 is frequently overexpressed and/or activated through mutations in bladder cancer, the functional importance of FGFR3 and its potential as a specific therapeutic target in this disease have not been elucidated in vivo. Here we report that inducible knockdown of FGFR3 in human bladder carcinoma cells arrested cell-cycle progression in culture and markedly attenuated tumor progression in xenografted mice. Further, we developed a unique antibody (R3Mab) that inhibited not only WT FGFR3, but also various mutants of the receptor, including disulfide-linked cysteine mutants. Biochemical analysis and 2.1-Å resolution crystallography revealed that R3Mab bound to a specific FGFR3 epitope that simultaneously blocked ligand binding, prevented receptor dimerization, and induced substantial conformational changes in the receptor. R3Mab exerted potent antitumor activity against bladder carcinoma and t(4;14)-positive multiple myeloma xenografts in mice by antagonizing FGFR3 signaling and eliciting antibody-dependent cell-mediated cytotoxicity (ADCC). These studies provide in vivo evidence demonstrating an oncogenic role of FGFR3 in bladder cancer and support antibody-based targeting of FGFR3 in hematologic and epithelial cancers driven by WT or mutant FGFR3.
PMCID: PMC2673861  PMID: 19381019
11.  Multiple myeloma: 2012 update on diagnosis, risk-stratification, and management 
American journal of hematology  2012;87(1):78-88.
Disease overview
Multiple myeloma accounts for ~10% of all hematologic malignancies.
The diagnosis requires 10% or more clonal plasma cells on bone marrow examination or a biopsy proven plasmacytoma plus evidence of end-organ damage felt to be related to the underlying plasma-cell disorder.
Risk stratification
Patients with 17p deletion, t(14;16), t(14;20), or high-risk gene expression profiling signature have high-risk myeloma. Patients with t(4;14) translocation, karyotypic deletion 13, or hypodiploidy are considered to have intermediate-risk disease. All others are considered to have standard-risk myeloma.
Risk-adapted therapy
Standard-risk patients are treated with nonalkylator-based therapy such as lenalidomide plus low-dose dexamethasone (Rd) followed by autologous stem-cell transplantation (ASCT). An alternative strategy is to continue initial therapy after stem-cell collection, reserving ASCT for first relapse. Intermediate-risk and high-risk patients are treated with a bortezomib-based induction followed by ASCT and then bortezomib-based maintenance. Patients not eligible for ASCT can be treated with Rd for standard risk disease, or with a bortezomib-based regimen if intermediate-risk or high-risk features are present. To reduce toxicity, when using bortezomib, the once-weekly subcutaneous dose is preferred; similarly, when using dexamethasone, the low-dose approach (40 mg once a week) is preferred, unless there is a need for rapid disease control.
Management of refractory disease
Patients with indolent relapse can be treated first with two-drug or three-drug combinations. Patients with more aggressive relapse often require therapy with a combination of multiple active agents. The most promising new agents in development are pomalidomide and carfilizomib.
PMCID: PMC3629949  PMID: 22180161
12.  Insulin like growth factor binding protein 7 (IGFBP7) expression is linked to poor prognosis but may protect from bone disease in multiple myeloma 
Insulin like growth factor binding protein 7 (IGFBP7) is a secreted protein binding insulin like growth factor 1 (IGF-1), insulin, vascular endothelial growth factor A (VEGFA), and activin A. It antagonizes bone morphogenetic proteins and is involved in the tumour propagation of solid as well as haematological malignancies. Its role in multiple myeloma (MM) is not defined so far. We therefore aim here to investigate its prognostic and pathophysiological role in MM.
The clinical significance of IGFBP7 gene expression was investigated by gene expression profiling in two independent cohorts (n = 948) of newly-diagnosed MM patients. Methylation of the IGFBP7 promoter was analysed by pyrosequencing and treatment of MM cell lines with 5-aza-2-deoxycytidine. The impact of IGFBP7 on MM cells was studied by CCK-8 assay, BrdU assay and flow cytometry, respectively. IGFBP7 expression in bone marrow stromal cells (BMSCs) was studied by quantitative RT-PCR. For osteoblast development, immortalized and primary human BMSCs were cultured in osteogenic differentiation medium for 7–14 days in the presence of recombinant human IGFBP7 and/or activin A.
Median IGFBP7 expression is significantly lower in CD138-purified plasma cells from individuals with MGUS and MM, compared to normal bone marrow plasma cells. IGFBP7 gene expression in MM cells is regulated by methylation, shown by pyrosequencing and exposure to demethylating agents (5-aza-2-deoxycytidine). High expression of IGFBP7 in MM cells is associated with adverse survival in two independent cohorts of 247 and 701 newly-diagnosed MM patients treated with high-dose therapy and autologous stem cell transplantation. IGFBP7 is associated with prognostically adverse chromosomal aberrations (t(4;14) and gain of 1q21), MMSET expression, and higher myeloma cell proliferation. In vitro, IGFBP7 overcomes activin A induced osteoblast suppression and promotes osteogenesis. MM cells downregulate IGFBP7 in stromal cells, possibly contributing to the osteoblast suppression found in MM. Conversely, higher IGFBP7 expression is associated with a lower probability of myeloma bone disease.
Our data indicate that IGFBP7 expression is a marker for a specific methylation pattern in myeloma, linked to translocation t(4;14) associated MMSET expression, showing clinical features of adverse prognosis with absence of myeloma bone disease.
Electronic supplementary material
The online version of this article (doi:10.1186/s13045-014-0105-1) contains supplementary material, which is available to authorized users.
PMCID: PMC4333268  PMID: 25887188
Multiple myeloma; IGFBP7; Microenvironment; Myeloma bone disease; Survival
13.  In Multiple Myeloma, 14q32 Translocations Are Non-Random Chromosomal Fusions Driving High Expression Levels of the Respective Partner Genes 
Genes, chromosomes & cancer  2014;53(7):549-557.
In studies of patients with multiple myeloma (MM), gene expression profiling (GEP) of myeloma cells demonstrates substantially higher expression of MMSET, FGFR3, CCND3, CCND1, MAF, and MAFB—the partner genes of 14q32 translocations—than GEP of plasma cells from healthy individuals. Interphase fluorescent in situ hybridization (FISH) was used to discriminate between chromosomal translocations involving different regions of the immunoglobulin heavy chain (IGH) genes at 14q32. With special probes designed for the constant region (IGHC) and the variable region (IGHV), IGH translocations were shown to be definite, non-random chromosomal fusions of IGHC with the loci of FGFR3, CCND1, CCND3, MAF, and MAFB genes; and IGHV with the locus of MMSET gene. When correlated with GEP results, the IGH translocations were found to drive expression levels of the partner genes to significantly higher levels (spikes) than copy-number variations. Hence, 42% of IGH translocations were identified among newly diagnosed MM patients (448/1,060). As GEP has become essential for assessing cancer risk, this novel approach is highly consistent with the cytogenetic features of the chromosomal translocations to effectively stratify molecular subgroups of MM on the basis of gene expression profiles of the IGH translocation partner genes in myeloma cells.
PMCID: PMC4016160  PMID: 24638926
Multiple myeloma; Chromosomal translocations; Gene expression profile
14.  Treatment of newly diagnosed myeloma 
Leukemia  2008;23(3):449-456.
The introduction of thalidomide, bortezomib and lenalidomide has dramatically changed the treatment paradigm of multiple myeloma (MM). In patients eligible for autologous stem cell transplant (ASCT), combinations including thalidomide/dexamethasone (Thal/Dex) or bortezomib/dexamethasone (Bort/Dex) or lenalidomide/dexamethasone (Rev/Dex) have been introduced as induction regimens in patients eligible for ASCT. New induction regimens have significantly increased complete response rate before and after ASCT with a positive impact on progression-free survival. Maintenance therapy with thalidomide, under investigation with lenalidomide, may further prolong remission duration. In patients not eligible for ASCT, randomized studies have shown that melphalan, prednisone, thalidomide (MPT) and melphalan, prednisone and bortezomib (MPV) are both superior to melphalan and prednisone (MP), and are now considered standard of care. Ongoing trials will soon assess if MP plus lenalidomide may be considered an attractive option. More complex regimens combining thalidomide or bortezomib or lenalidomide with cyclophosphamide or doxorubicin have been also tested. In small cohorts of patients bortezomib or lenalidomide may overcome the poor prognosis induced by deletion 13 or translocation t(4;14) or deletion 17p13. If these data will be confirmed, a cytogenetically riskadapted strategy might become the most appropriate strategy.
PMCID: PMC3923468  PMID: 19005483
new drugs; therapy; diagnosis; myeloma
15.  Pomalidomide: a novel drug to treat relapsed and refractory multiple myeloma 
OncoTargets and therapy  2013;6:531-538.
Multiple myeloma remains an incurable disease despite the introduction of the immunomodulatory drugs (IMiDs) thalidomide and lenalidomide and the proteasome inhibitor bortezomib that have improved the outcome of patients with both newly diagnosed and relapsed/refractory disease. However, patients who relapse after treatment with these agents or are refractory to them represent an unmet need and highlight the necessity for the development of novel anti-myeloma agents. Pomalidomide is an IMiD, structurally related to thalidomide, with enhanced antiangiogenic, antineoplastic, and anti-inflammatory properties and exhibiting potent anti-myeloma activity in vitro and in vivo. Pomalidomide has shown remarkable activity in patients who were refractory to both bortezomib and lenalidomide in Phase II and III studies. This paper reviews the chemistry and mechanisms of action of pomalidomide as well as all the available data from clinical trials on pomalidomide use in patients with refractory/relapsed multiple myeloma.
PMCID: PMC3656921  PMID: 23690693
immunomodulatory drugs; cereblon; angiogenesis; lenalidomide; refractory
16.  Fibroblast growth factor signaling and inhibition in non-small cell lung cancer and their role in squamous cell tumors 
Cancer Medicine  2014;3(3):681-692.
With the introduction of targeted agents primarily applicable to non-small cell lung cancer (NSCLC) of adenocarcinoma histology, there is a heightened unmet need in the squamous cell carcinoma population. Targeting the angiogenic fibroblast growth factor (FGF)/FGF receptor (FGFR) signaling pathway is among the strategies being explored in squamous NSCLC; these efforts are supported by growth-promoting effects of FGF signaling in preclinical studies (including interactions with other pathways) and observations suggesting that FGF/FGFR-related aberrations may be more common in squamous versus adenocarcinoma and other histologies. A number of different anti-FGF/FGFR approaches have shown promise in preclinical studies. Clinical trials of two multitargeted tyrosine kinase inhibitors are restricting enrollment to patients with squamous NSCLC: a phase I/II trial of nintedanib added to first-line gemcitabine/cisplatin and a phase II trial of ponatinib for previously treated advanced disease, with the latter requiring not only squamous disease but also a confirmed FGFR kinase amplification or mutation. There are several ongoing clinical trials of multitargeted agents in general NSCLC populations, including but not limited to patients with squamous disease. Other FGF/FGFR-targeted agents are in earlier clinical development. While results are awaited from these clinical investigations in squamous NSCLC and other disease settings, additional research is needed to elucidate the role of FGF/FGFR signaling in the biology of NSCLC of different histologies.
PMCID: PMC4101760  PMID: 24711160
Angiogenesis inhibitors; fibroblast growth factors; non-small cell lung cancer; squamous cell carcinoma
17.  Fibroblast Growth Factor Receptor 3 Associates with and Tyrosine Phosphorylates p90 RSK2, Leading to RSK2 Activation That Mediates Hematopoietic Transformation▿  
Molecular and Cellular Biology  2009;29(8):2105-2117.
Dysregulation of the receptor tyrosine kinase fibroblast growth factor receptor 3 (FGFR3) plays a pathogenic role in a number of human hematopoietic malignancies and solid tumors. These include t(4;14) multiple myeloma associated with ectopic expression of FGFR3 and t(4;12)(p16;p13) acute myeloid leukemia associated with expression of a constitutively activated fusion tyrosine kinase, TEL-FGFR3. We recently reported that FGFR3 directly tyrosine phosphorylates RSK2 at Y529, which consequently regulates RSK2 activation. Here we identified Y707 as an additional tyrosine in RSK2 that is phosphorylated by FGFR3. Phosphorylation at Y707 contributes to RSK2 activation, through a putative disruption of the autoinhibitory αL-helix on the C terminus of RSK2, unlike Y529 phosphorylation, which facilitates ERK binding. Moreover, we found that FGFR3 interacts with RSK2 through residue W332 in the linker region of RSK2 and that this association is required for FGFR3-dependent phosphorylation of RSK2 at Y529 and Y707, as well as the subsequent RSK2 activation. Furthermore, in a murine bone marrow transplant assay, genetic deficiency in RSK2 resulted in a significantly delayed and attenuated myeloproliferative syndrome induced by TEL-FGFR3 as compared with wild-type cells, suggesting a critical role of RSK2 in FGFR3-induced hematopoietic transformation. Our current and previous findings represent a paradigm for tyrosine phosphorylation-dependent regulation of serine-threonine kinases.
PMCID: PMC2663316  PMID: 19223461
18.  Inhibition of cell cycle progression by dual phosphatidylinositol-3-kinase and mTOR blockade in cyclin D2 positive multiple myeloma bearing IgH translocations 
Blood Cancer Journal  2012;2(1):e50-.
Multiple myeloma (MM) is a clinically and genetically heterogenous cancer where tumour cells have dysregulated expression of a D-type cyclin, often in association with a recurrent IgH translocation. Patients whose tumour cells express cyclin D2, with the translocation t(4;14) or t(14;16), generally have more proliferative disease and inferior outcomes. The phosphatidylinositol-3-kinase (PI3K) pathway is a major regulator of D-type cyclin expression and cell cycle entry. We evaluated the effect of PI3K pathway blockade on cell cycle behaviour in MM cells, investigating differences between cyclin D2- and cyclin D1-expressing tumours. MM cell lines and primary bone marrow CD138+ MM cells were exposed to the pan-PI3K/mTOR inhibitor, PI-103, and assessed for cell cycle profiles, [3H]-thymidine uptake and cell cycle proteins. We report, in both cell lines and primary MM cells, that PI-103 induced cell cycle arrest with downregulation of cyclin D2 and CDK4/6 in MM cells expressing cyclin D2 via t(4;14) or t(14;16) translocations. Cells expressing cyclin D1 via t(11;14) were insensitive to PI-103, despite exhibiting inhibition of downstream signalling targets. In primary MM cells, PI-103 enhanced the anti-proliferative effects of anti-MM agents. Treatment paradigms including blockade of the PI3K/mTOR pathway should be targeted at patients with IgH translocations associated with cyclin D2 overexpression.
PMCID: PMC3270251  PMID: 22829234
multiple myeloma; cyclin D; cell cycle; PI3K/mTOR; PI-103
19.  Differential regulation of FGFR3 by PTPN1 and PTPN2 
Proteomics  2014;15(2-3):419-433.
Aberrant expression and activation of FGFR3 is associated with disease states including bone dysplasia and malignancies of bladder, cervix, and bone marrow. MS analysis of protein-phosphotyrosine in multiple myeloma cells revealed a prevalent phosphorylated motif, D/EYYR/K, derived from the kinase domain activation loops of tyrosine kinases including FGFR3 corresponding to a recognition sequence of phosphotyrosine phosphatases PTPN1. Knockdown of PTPN1 or the related enzyme PTPN2 by RNAi resulted in ligand-independent activation of FGFR3. Modulation of FGFR3 activation loop phosphorylation by both PTPN1 and PTPN2 was a function of receptor trafficking and PTP compartmentalization. The FGFR3 activation loop motif DYYKK650 is altered to DYYKE650 in the oncogenic variant FGFR3K650E, and consequently it is constitutively fully activated and unaffected by activation loop phosphorylation. FGFR3K650E was nevertheless remarkably sensitive to negative regulation by PTPN1 and PTPN2. This suggests that in addition to modulating FGFR3 phosphorylation, PTPN1 and PTPN2 constrain the kinase domain by fostering an inactive-state. Loss of this constraint in response to ligand or impaired PTPN1/N2 may initiate FGFR3 activation. These results suggest a model wherein PTP expression levels may define conditions that select for ectopic FGFR3 expression and activation during tumorigenesis.
PMCID: PMC5032629  PMID: 25311528
activation loop; endocytosis; glycosylation; multiple myeloma; phosphorylation; trafficking; tyrosine kinase
20.  NSD2 links dimethylation of histone H3 at lysine 36 to oncogenic programming 
Molecular cell  2011;44(4):609-620.
The histone lysine methyltransferase NSD2 (MMSET/WHSC1) is implicated in diverse diseases and commonly overexpressed in multiple myeloma due to a recurrent t(4;14) chromosomal translocation. However, the precise catalytic activity of NSD2 is obscure, preventing progress in understanding how this enzyme influences chromatin biology and myeloma pathogenesis. Here we show that dimethylation of histone H3 at lysine 36 (H3K36me2) is the principal chromatin-regulatory activity of NSD2. Catalysis of H3K36me2 by NSD2 is sufficient for gene activation. In t(4;14)-positive myeloma cells, the normal genome-wide and gene-specific distribution of H3K36me2 is obliterated, creating a chromatin landscape that selects for a transcription profile favorable for myelomagenesis. Catalytically active NSD2 confers xenograft tumor formation upon t(4;14)-negative cells, and promotes oncogenic transformation of primary cells in an H3K36me2-dependent manner. Together our findings establish H3K36me2 as the primary product generated by NSD2, and demonstrate that genomic disorganization of this canonical chromatin mark by NSD2 initiates oncogenic programming.
PMCID: PMC3222870  PMID: 22099308
21.  Transforming Fusions of FGFR and TACC Genes in Human Glioblastoma 
Science (New York, N.Y.)  2012;337(6099):1231-1235.
The brain tumor glioblastoma multiforme (GBM) is among the most lethal forms of human cancer. Here, we report that a small subset of GBMs (3.1%; 3 of 97 tumors examined) harbors oncogenic chromosomal translocations that fuse in-frame the tyrosine kinase coding domains of fibroblast growth factor receptor (FGFR) genes (FGFR1 or FGFR3) to the transforming acidic coiled-coil (TACC) coding domains of TACC1 or TACC3, respectively. The FGFR-TACC fusion protein displays oncogenic activity when introduced into astrocytes or stereotactically transduced in the mouse brain. The fusion protein, which localizes to mitotic spindle poles, has constitutive kinase activity and induces mitotic and chromosomal segregation defects and triggers aneuploidy. Inhibition of FGFR kinase corrects the aneuploidy, and oral administration of an FGFR inhibitor prolongs survival of mice harboring intracranial FGFR3-TACC3–initiated glioma. FGFR-TACC fusions could potentially identify a subset of GBM patients who would benefit from targeted FGFR kinase inhibition.
PMCID: PMC3677224  PMID: 22837387
22.  International Myeloma Working Group molecular classification of multiple myeloma: spotlight review 
Myeloma is a malignant proliferation of monoclonal plasma cells. Although morphologically similar, several subtypes of the disease have been identified at the genetic and molecular level. These genetic subtypes are associated with unique clinico-pathological features and dissimilar outcome. At the top hierarchical level, myeloma can be divided into hyperdiploid and non-hyperdiploid subtypes. The latter is mainly composed of cases harboring IgH translocations, generally associated with more aggressive clinical features and shorter survival. The three main IgH translocations in myeloma are the t(11;14)(q13;q32), t(4;14)(p16;q32) and t(14;16)(q32;q23). Trisomies and a more indolent form of the disease characterize hyperdiploid myeloma. A number of genetic progression factors have been identified including deletions of chromosomes 13 and 17 and abnormalities of chromosome 1 (1p deletion and 1q amplification). Other key drivers of cell survival and proliferation have also been identified such as nuclear factor- B-activating mutations and other deregulation factors for the cyclin-dependent pathways regulators. Further understanding of the biological subtypes of the disease has come from the application of novel techniques such as gene expression profiling and array-based comparative genomic hybridization. The combination of data arising from these studies and that previously elucidated through other mechanisms allows for most myeloma cases to be classified under one of several genetic subtypes. This paper proposes a framework for the classification of myeloma subtypes and provides recommendations for genetic testing. This group proposes that genetic testing needs to be incorporated into daily clinical practice and also as an essential component of all ongoing and future clinical trials.
PMCID: PMC2964268  PMID: 19798094
multiple myeloma; genetics; cytogenetics; molecular; prognosis; gene expression profiling
23.  Characterization of fibroblast growth factor receptor 2 overexpression in the human breast cancer cell line SUM-52PE 
Breast Cancer Research : BCR  2000;2(4):311-320.
The fibroblast growth factor receptor (FGFR)2 gene has been shown to be amplified in 5-10% of breast cancer patients. A breast cancer cell line developed in our laboratory, SUM-52PE, was shown to have a 12-fold amplification of the FGFR2 gene, and FGFR2 message was found to be overexpressed 40-fold in SUM-52PE cells as compared with normal human mammary epithelial (HME) cells. Both human breast cancer (HBC) cell lines and HME cells expressed two FGFR2 isoforms, whereas SUM-52PE cells overexpressed those two isoforms, as well as several unique FGFR2 polypeptides. SUM-52PE cells expressed exclusively FGFR2-IIIb isoforms, which are high-affinity receptors for fibroblast growth factor (FGF)-1 and FGF-7. Differences were identified in the expression of the extracellular Ig-like domains, acid box and carboxyl termini, and several variants not previously reported were isolated from these cells.
The FGFR family of receptor tyrosine kinases includes four members, all of which are highly alternatively spliced and glycosylated. For FGFR2, alternative splicing of the second half of the third Ig-like domain, involving exons IIIb and IIIc, is a mutually exclusive choice that affects ligand binding specificity and affinity [1,2,3]. It appears that the second half of the third Ig-like domain can dictate high affinity for FGF-2 or keratinocyte growth factor (KGF), whereas affinity for FGF-1 appears to remain the same [3]. Alternative splicing of the carboxyl terminus has been shown to involve at least two different exons that can produce at least three different variants. The C1-type and C2-type carboxyl termini are encoded by the same exon, and have two different splice acceptor sites, whereas the C3-type carboxyl terminus is encoded by a separate exon [4]. The biologic significance of the C1 carboxyl terminus, as compared with the shorter C3 variant found primarily in tumorigenic samples, has been studied in NIH3T3 transfection assays, in which C3 variants were able to produce three times more transformed foci in soft agar than C1 variants (both IIIb), whereas full length FGFR2 and FGFR1 (both IIIc variants) showed no transforming activity [4].
Previous studies [5,6] have found amplification and overexpression of FGFR2 in 5-10% of primary breast cancer specimens. A recent study [7] done using a tissue array consisting of 372 primary breast cancer specimens found a 5% incidence of FGFR2 amplification. To our knowledge, none of the HBC cell lines studied thus far have an FGFR2 gene amplification, although overexpression of FGFR2 message and protein has been documented for some breast cancer cell lines [6,8,9].
SUM-52PE is a breast cancer cell line previously isolated in our laboratory that grows under serum-free and epidermal growth factor-free conditions, has high levels of tyrosine-phosphorylated membrane proteins, and has the capacity to invade and grow under anchorage-independent conditions [10,11,12]. This cell line exhibits all of the important hallmarks of transformed, highly malignant cells. Therefore, SUM-52PE was used as a model to study the diversity of FGFR2 expression in a breast cancer cell line that has true amplification and overexpression of FGFR2.
This study was conducted to examine the degree of FGFR2 amplification and overexpression in the breast cancer cell line SUM-52PE. Subsequent sequencing and characterization of individual FGFR2 variants cloned from the SUM-52PE cell line was completed to determine the complexity of FGFR2 alternative splicing in the context of a highly metastatic breast cancer cell line.
Southern, Northern and Western blot analyses were done in order to determine the degree of FGFR2 amplification and overexpression in the breast cancer cell line SUM-52PE. Individual FGFR2 variants were cloned out of SUM-52PE using FGFR2-specific primers in a reverse transcription (RT) polymerase chain reaction (PCR). FGFR2 cDNAs were characterized by restriction fragment analysis, sequencing and transient transfection into 293 cells to examine the protein expression of each FGFR2 clone.
The results of the Southern blot showed that there was a 12-fold amplification of FGFR2 in the SUM-52PE cell line. Northern blot analysis of SUM-52PE showed FGFR2 transcripts to be highly overexpressed compared with other breast cancer cell lines and normal HME cells. Several overexpressed bands of approximately 6.3, 5.0, 4.0, and 2.8kb were observed in SUM-52PE cells. The most prominent band, at 2.8kb, was so abundant that it was difficult to discern other individual bands clearly. Western blot analysis showed that both normal HME and HBC cells expressed two FGFR2 variants of 95 and 135kDa. The SUM-52PE cell line greatly overexpressed not only these two polypeptides, as compared with HME and HBC cells, but also overexpressed two unique variants of FGFR2 - 85 and 109kDa polypeptides - as well as several smaller polypeptides in the 46-53kDa range. The antibody used in Western blot analysis only recognizes FGFR2 isoforms that express the C1 carboxyl termini, therefore greatly underestimating the actual number of different FGFR2 variants that are overexpressed in this cell line.
PCR was performed to determine the proportion of C1/C2 variants as compared with C3 variants in the SUM-52PE cell line. Results of this analysis indicated the presence of all three types of variants in this cell line, although the C1/C2 variants were predominant as compared with the C3 variants in SUM-52PE.
Four different FGFR2-C1 clones were isolated and sequenced from SUM-52PE cells, which differed in their signal sequence, first Ig-like loop, and acid box. Two FGFR2-C2 clones were isolated from the SUM-52PE cell line, which were identical to each other except for the variable expression of the number of Ig-like domains (two or three). Three C3 clones were isolated and sequenced, two of which have not previously been described in the literature. Clone C3-#3 contained two Ig-like domains, but no acid box. C3-#5 was missing the first two Ig-like domains and the acid box, but did contain the third Ig-like domain.
There is an extensive amount of evidence implicating erbB-2, a gene that is overexpressed in approximately 30% of breast cancer cases, as a breast cancer gene [13]. The identification of other breast oncogenes that function in the remaining 70% of cases is an ongoing challenge, as is establishing a causal role for such oncogenes in HME cell transformation.
FGFR1 and FGFR2, previously established oncogenes, were found to be amplified within large amplicons on 8p11 and 10q26, respectively, in the breast cancer cell line SUM-52PE [14]. Previous studies have shown that the FGFR2 gene is amplified in about 5-10% of breast cancer cases.
Our results showed that SUM-52PE cells overexpressed many alternatively spliced isoforms of FGFR2 at both the transcript and protein level as compared with normal HME cells. The variability in FGFR2 isoform expression is complex and involves exon IIIb/c, which encodes the second half of the third Ig-like loop; variations in the carboxyl terminal end of the receptor, involving the C1/C2 or C3 domains; and variable expression of the Ig-like loops and acid box in the extracellular portion of the receptor. The characterization of three unique FGFR2 isoforms that were cloned from SUM-52PE may build on the findings of others concerning the transforming potential of FGFR2 variants [4]. In particular, because it has been demonstrated that expression of C3-IIIb variants may have more transforming activity than C1-IIIb variants, differences between the three C3 clones we have isolated may provide information regarding the influence of particular structural domains on transforming potential.
Ongoing studies are aimed at characterizing the transforming ability of FGFR2 isoforms obtained from SUM-52PE cells by transducing these genes into normal HME cells. By overexpressing FGFR2 isoforms in a physiologically relevant system, we hope to determine the isoform(s) that acts in a dominant way in the process of cell transformation, and to determine whether different regions present in individual clones drive specific phenotypes associated with transformation.
PMCID: PMC13919  PMID: 11056689
alternative splicing; breast cancer; fibroblast growth factor receptor; receptor tyrosine kinase; SUM-52PE
24.  Extramedullary progression of multiple myeloma despite concomitant medullary response to multiple combination therapies and autologous transplant: a case report 
Extramedullary myeloma that occurs during the clinical course of multiple myeloma is rare but is an independent poor prognostic factor with mortality of 73% and median survival of 12 months despite aggressive therapies including novel agents. The clinicopathological aspects, biology and management of extramedullary myelomas are poorly understood. Our case highlights the pathobiological aspects of this important but rare entity, and the repercussions of modern therapies.
Case presentation
A 60-year-old Caucasian man initially presented with an anterior rib fracture. Subsequent workup revealed stage IIIB immunoglobulin G lambda multiple myeloma. A bone marrow biopsy showed sheets of plasma cells, harboring unfavorable cytogenetics including deletion of 17p and t(4;14). He achieved near complete remission and resolution of karyotypic abnormalities with three cycles of induction doxorubicin, thalidomide, and dexamethasone (clinical trial). This was followed by high-dose melphalan and autologous stem cell transplant. He relapsed 1 year later. His bone marrow at that time showed only a few scattered polyclonal plasma cells. He received three cycles of bortezomib and tanespimycin (clinical trial) and achieved very good partial response. He again relapsed 1 year later with multiple large peripheral soft tissue masses and lymph nodes. Biopsies of the peripheral lesions were consistent with extramedullary myeloma, but repeat bone marrow biopsy continued to show no evidence of intramedullary disease.
This is one of the few cases reported that illustrates the differential response of extramedullary compared to intramedullary myeloma to multiple standard combination therapies including novel therapeutics and transplant, resulting in a very short survival. Several mechanisms for intra-to-extra medullary migration and hence the differential treatment response have been hypothesized. Physicians should be aware of this problem during treatment with immunomodulatory drugs and proteasome inhibitors not only in relapsed but also in front-line setting. In such cases, there is a potential role for evolving targeted therapeutics as we continue to better understand the tumor biology.
PMCID: PMC4168996  PMID: 25200389
Extramedullary; Multiple myeloma; Plasmacytoma
25.  In Vitro and In Vivo Activity of a Novel Locked Nucleic Acid (LNA)-Inhibitor-miR-221 against Multiple Myeloma Cells 
PLoS ONE  2014;9(2):e89659.
Background & Aim
The miR-221/222 cluster is upregulated in malignant plasma cells from multiple myeloma (MM) patients harboring the t(4;14) translocation. We previously reported that silencing of miR-221/222 by an antisense oligonucleotide induces anti-MM activity and upregulates canonical miR-221/222 targets. The in vivo anti-tumor activity occurred when miR-221/222 inhibitors were delivered directly into MM xenografts. The aim of the present study was to evaluate the anti-MM activity of a novel phosphorothioate modified backbone 13-mer locked nucleic acid (LNA)-Inhibitor-miR-221 (LNA-i-miR-221) specifically designed for systemic delivery.
In vitro anti-MM activity of LNA-i-miR-221 was evaluated by cell proliferation and BrdU uptake assays. In vivo studies were performed with non-obese diabetic/severe combined immunodeficient (NOD.SCID) mice bearing t(4;14) MM xenografts, which were intraperitoneally or intravenously treated with naked LNA-i-miR-221. RNA extracts from retrieved tumors were analyzed for miR-221 levels and modulation of canonical targets expression. H&E staining and immunohistochemistry were performed on retrieved tumors and mouse vital organs.
In vitro, LNA-i-miR-221 exerted strong antagonistic activity against miR-221 and induced upregulation of the endogenous target p27Kip1. It had a marked anti-proliferative effect on t(4;14)-translocated MM cells but not on MM cells not carrying the translocation and not overexpressing miR-221. In vivo, systemic treatment with LNA-i-miR-221 triggered significant anti-tumor activity against t(4;14) MM xenografts; it also induced miR-221 downregulation, upregulated p27Kip1 and reduced Ki-67. No behavioral changes or organ-related toxicity were observed in mice as a consequence of treatments.
LNA-i-miR-221 is a highly stable, effective agent against t(4;14) MM cells, and is suitable for systemic use. These data provide the rationale for the clinical development of LNA-i-miR-221 for the treatment of MM.
PMCID: PMC3931823  PMID: 24586944

Results 1-25 (1634471)