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1.  Lenalidomide inhibits lymphangiogenesis in preclinical models of mantle cell lymphoma 
Cancer research  2013;73(24):7254-7264.
Lymphomas originate in and spread primarily along the lymphatic system. However, whether lymphatic vessels contribute to the growth and spreading of lymphomas is largely unclear. Mantle cell lymphoma (MCL) represents an aggressive non-Hodgkin's lymphoma. We found that MCL exhibited abundant intratumor lymphatic vessels. Our results demonstrated that the immunomodulatory drug lenalidomide potently inhibited the growth and dissemination of MCL in a xenograft MCL mouse model, at least in part, by inhibiting functional tumor lymphangiogenesis. Significant numbers of tumor-associated macrophages expressing vascular endothelial growth factor-C were found in both human MCL and mouse MCL xenograft samples. Lenalidomide treatment resulted in a significant reduction in the number of MCL-associated macrophages. In addition, in vivo depletion of monocytes/macrophages impaired functional tumor lymphangiogenesis and inhibited MCL growth and dissemination. Taken together, our results indicate that tumor lymphangiogenesis contributes to the progression of MCL and that lenalidomide is effective in decreasing MCL growth and metastasis most likely by inhibiting recruitment of MCL-associated macrophages.
PMCID: PMC3947537  PMID: 24158094
lymphangiogenesis; mantle cell lymphoma; lenalidomide; macrophage; metastasis
2.  An Improved Cryosection Method for Polyethylene Glycol Hydrogels Used in Tissue Engineering 
Tissue Engineering. Part C, Methods  2013;19(10):794-801.
The high water content of hydrogels allows these materials to closely mimic the native biological extracellular conditions, but it also makes difficult the histological preparation of hydrogel-based bioengineered tissue. Paraffin-embedding techniques require dehydration of hydrogels, resulting in substantial collapse and deformation, whereas cryosectioning is hampered by the formation of ice crystals within the hydrogel material. Here, we sought to develop a method to obtain good-quality cryosections for the microscopic evaluation of hydrogel-based tissue-engineered constructs, using polyethylene glycol (PEG) as a test hydrogel. Conventional sucrose solutions, which dehydrate cells while leaving extracellular water in place, produce a hydrogel block that is brittle and difficult to section. We therefore replaced sucrose with multiple protein-based and nonprotein-based solutions as cryoprotectants. Our analysis demonstrated that overnight incubation in bovine serum albumin (BSA), fetal bovine serum (FBS), polyvinyl alcohol (PVA), optimum cutting temperature (OCT®) compound, and Fisher HistoPrep frozen tissue-embedding media work well to improve the cryosectioning of hydrogels. The protein-based solutions give background staining with routine hematoxylin and eosin, but the use of nonprotein-based solutions PVA and OCT reduces this background by 50%. These methods preserve the tissue architecture and cellular details with both in vitro PEG constructs and in constructs that have been implanted in vivo. This simple hydrogel cryosectioning technique improves the methodology for creation of good-quality histological sections from hydrogels in multiple applications.
PMCID: PMC3751207  PMID: 23448137
3.  EZH2 Mutations Are Related to Low Blast Percentage in Bone Marrow and -7/del(7q) in De Novo Acute Myeloid Leukemia 
PLoS ONE  2013;8(4):e61341.
The purpose of the present work was to determine the incidence and clinical implications of somatic EZH2 mutations in 714 patients with de novo acute myelogenous leukemia by sequencing the entire coding region. EZH2 mutations were identified in 13/714 (1.8%) of AML patients were found to be more common in males (P = 0.033). The presence of EZH2 mutations was significantly associated with lower blast percentage (21–30%) in bone marrow (P<0.0001) and -7/del(7q) (P = 0.025). There were no differences in the incidence of mutation in 13 genes, ASXL1, CBL, c-KIT, DNMT3A, FLT3, IDH1, IDH2, MLL, NPM1, NRAS, RUNX1, TET2, and WT1, between patients with and without EZH2 mutations. No difference in complete remission, event-free survival, or overall survival was observed between patients with and without EZH2 mutation (P>0.05). Overall, these results showed EZH2 mutation in de novo acute myeloid leukemia as a recurrent genetic abnormality to be associated with lower blast percentage in BM and -7/del(7q).
PMCID: PMC3629223  PMID: 23613835
4.  Durable Responses with the Metronomic Regimen RT-PEPC in Elderly Patients with Recurrent Mantle Cell Lymphoma 
Cancer  2010;116(11):2655-2664.
Targeting the tumor microenvironment and angiogenesis is a novel lymphoma therapeutic strategy. We report safety, activity and angiogenic profiling with the RT-PEPC regimen (rituximab with thalidomide, and prednisone, etoposide, procarbazine and cyclophosphamide) in recurrent mantle cell lymphoma (MCL).
RT-PEPC includes induction (months 1–3) of weekly rituximab × 4, daily thalidomide (50 mg) and PEPC, then maintenance thalidomide (100 mg), oral PEPC titrated to neutrophil count, and rituximab every 4 months. Endpoints included safety, efficacy, quality of life (QoL), and translational studies including tumor angiogenic phenotyping, plasma VEGF and circulating endothelial cells.
Twenty-five pts were enrolled (22 evaluable) with median age 68 yrs (range 52–81), 24 (96%) stage III/IV, 18 (72%) IPI 3–5, 20 (80%) high risk MIPI, median 2 prior therapies (range 1–7), and 15 (60%) bortezomib progressors. At a median follow-up of 38 months, ORR was 73% (32% CR/CRu, 41% PR, n=22) and median PFS 10 months. Four CRs are ongoing (6+, 31+, 48+ and 50+ months). Toxicities included grade 1–2 fatigue, rash, neuropathy and cytopenias including grade 1–2 thrombocytopenia (64%) and grade 3–4 neutropenia (64%). Two thromboses and 5 grade 3–4 infections occurred. QoL was maintained or improved. Correlative studies demonstrated tumor autocrine angiogenic loop (expression of VEGFA and VEGFR1) and heightened angiogenesis and lymphangiogenesis in stroma. Plasma VEGF and circulating endothelial cells trended down with treatment.
RT-PEPC has significant and durable activity in MCL, with manageable toxicity and maintained QoL. Novel low-intensity approaches warrant further evaluation, potentially as initial therapy in elderly patients.
PMCID: PMC3004744  PMID: 20235190
5.  Targeting angiogenesis: A novel, rational therapeutic approach for Non-Hodgkin’s Lymphoma 
Leukemia & lymphoma  2009;50(5):679.
PMCID: PMC2819380  PMID: 19452312
6.  Evidence for a capping enzyme with specificity for the trypanosome spliced leader RNA 
Capping of the pre-mRNA 5′ end by addition a monomethylated guanosine cap (m7G) is an essential and the earliest modification in the biogenesis of mRNA. The reaction is catalyzed by three enzymes: triphosphatase, guanylyltransferase, and (guanine N-7) methyltransferase. Whereas this modification occurs co-transcriptionally in most eukaryotic organisms, trypanosomatid protozoa mRNAs acquire the m7G cap by trans-splicing, which entails the transfer of the capped spliced leader (SL) from the SL RNA to the mRNA. Intriguingly, the genomes of all trypanosomatid protozoa sequenced to date possess two distinct proteins with the signature motifs of guanylyltransferases: TbCGM1 and the previously characterized TbCE1. Here we provide biochemical evidence that TbCgm1 is a capping enzyme. Whereas RNAi-induced downregulation of TbCe1 had no phenotypic consequences, we found that TbCGM1 is essential for trypanosome viability and is required for SL RNA capping. Furthermore, consistent with co-transcriptional addition of the m7G cap, chromatin immunoprecipitation revealed recruitment of TbCgm1 to the SL RNA genes.
PMCID: PMC2706020  PMID: 17949828
mRNA capping; guanylyltransferase; cap 4 modification; trans-splicing; SL RNA; RNAi
7.  Genomic rearrangements and transcriptional analysis of the spliced leader-associated retrotransposon in RNA interference-deficient Trypanosoma brucei 
Molecular microbiology  2007;67(2):435-447.
The Trypanosoma brucei genome is colonized by the site-specific non-LTR retrotransposon SLACS, or spliced leader-associated conserved sequence, which integrates exclusively into the spliced leader (SL) RNA genes. Although there is evidence that the RNA interference (RNAi) machinery regulates SLACS transcript levels, we do not know whether RNAi deficiency affects the genomic stability of SLACS, nor do we understand the mechanism of SLACS transcription. Here, we report that prolonged culturing of RNAi-deficient T. brucei cells, but not wild-type cells, results in genomic rearrangements of SLACS. Furthermore, two populations of SLACS transcripts persist in RNAi-deficient cells: a full-length transcript of approximately 7 kb and a heterogeneous population of small SLACS transcripts ranging in size from 450 to 550 nt. We provide evidence that SLACS transcription initiates at the +1 of the interrupted SL RNA gene and proceeds into the 5′ UTR and open reading frame 1 (ORF1). This transcription is carried out by an RNA polymerase with α-amanitin sensitivity reminiscent of SL RNA synthesis and is dependent on the SL RNA promoter. Additionally, we show that both sense and antisense small SLACS transcripts originate from ORF1 and that they are associated with proteins in vivo. We speculate that the small SLACS transcripts serve as substrates for the production of siRNAs to regulate SLACS expression.
PMCID: PMC2610267  PMID: 18067542
8.  Characterization of the Trypanosoma brucei cap hypermethylase Tgs1 
PMCID: PMC2075351  PMID: 17610965
TMG cap; U2 snRNA; U3 snoRNA; RNAi; Nop10
9.  Functional Characterization of a Trypanosoma brucei TATA-Binding Protein-Related Factor Points to a Universal Regulator of Transcription in Trypanosomes 
Molecular and Cellular Biology  2004;24(21):9610-9618.
Transcriptional mechanisms remain poorly understood in trypanosomatid protozoa. In particular, there is no knowledge about the function of basal transcription factors, and there is an apparent rarity of promoters for protein-coding genes transcribed by RNA polymerase (Pol) II. Here we describe a Trypanosoma brucei factor related to the TATA-binding protein (TBP). Although this TBP-related factor (TBP-related factor 4 [TRF4]) has about 31% identity to the TBP core domain, several key residues involved in TATA box binding are not conserved. Depletion of the T. brucei TRF4 (TbTRF4) by RNA interference revealed an essential role in RNA Pol I, II, and III transcription. Using chromatin immunoprecipitation, we further showed that TRF4 is recruited to the Pol I-transcribed procyclic acidic repetitive genes, Pol II-transcribed spliced leader RNA genes, and Pol III-transcribed U-snRNA and 7SL RNA genes, thus supporting a role for TbTRF4 in transcription performed by all three nuclear RNA polymerases. Finally, a search for TRF4 binding sites in the T. brucei genome led to the identification of such sites in the 3′ portion of certain protein-coding genes, indicating a unique aspect of Pol II transcription in these organisms.
PMCID: PMC522245  PMID: 15485927
10.  noxR3, a Novel Gene from Mycobacterium tuberculosis, Protects Salmonella typhimurium from Nitrosative and Oxidative Stress 
Infection and Immunity  1999;67(7):3276-3283.
Reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) produced by activated macrophages participate in host defense against the facultative intracellular pathogens Mycobacterium tuberculosis and Salmonella typhimurium. To survive within macrophages, such pathogens may have evolved ROI and RNI resistance mechanisms. ROI resistance pathways have been intensively studied. Much less is known about the mechanisms of resistance to RNI. To identify possible RNI resistance genes in M. tuberculosis, a mycobacterial library was expressed in S. typhimurium and subjected to selection by exposure to the NO donor S-nitrosoglutathione (GSNO) in concentrations sufficient to kill the vast majority of nontransformed salmonellae. Among the rare surviving recombinants was a clone expressing noxR3, a novel and previously anonymous M. tuberculosis gene predicted to encode a small, basic protein. Expression of noxR3 protected S. typhimurium not only from GSNO and acidified nitrite but also from H2O2. noxR3 is the third gene cloned from M. tuberculosis that has been shown to protect heterologous cells from both RNI and ROI. This suggests diversity in the repertoire of mechanisms that help pathogens resist the oxidative and nitrosative defenses of the host.
PMCID: PMC116506  PMID: 10377101
11.  A Novel Antioxidant Gene from Mycobacterium tuberculosis  
The Journal of Experimental Medicine  1997;186(11):1885-1896.
Among the major antimicrobial products of macrophages are reactive intermediates of the oxidation of nitrogen (RNI) and the reduction of oxygen (ROI). Selection of recombinants in acidified nitrite led to the cloning of a novel gene, noxR1, from a pathogenic clinical isolate of Mycobacterium tuberculosis. Expression of noxR1 conferred upon Escherichia coli and Mycobacterium smegmatis enhanced ability to resist RNI and ROI, whether the bacteria were exposed to exogenous compounds in medium or to endogenous products in macrophages. These studies provide the first identification of an RNI resistance mechanism in mycobacteria, point to a new mechanism for resistance to ROI, and raise the possibility that inhibition of the noxR1 pathway might enhance the ability of macrophages to control tuberculosis.
PMCID: PMC2199150  PMID: 9382887

Results 1-11 (11)