Secondary hemophagocytic syndrome after autologous hematopoietic cell transplant and immune therapy for neuroblastoma.

Secondary hemophagocytic syndrome (HPS) has been described after autologous hematopoietic cell transplant (AutoHCT). We report two cases of secondary HPS after novel consolidation therapy for high-risk neuroblastoma as part of an institutional phase 2 trial incorporating immunotherapy into a "standard" AutoHCT regimen. Both patients developed liver dysfunction beyond expected course of hepatic veno-occlusive disease, coagulopathy, hyperferritinemia, and when evaluated, elevated soluble interleukin-2 receptor and hemophagocytosis. These cases highlight the need for clinicians to have a high index of suspicion for immune-related complications in patients receiving immune therapies.

Lenalidomide targets clonogenic side population in multiple myeloma: pathophysiologic and clinical implications.

Recurrence of multiple myeloma (MM) after therapy suggests the presence of tumor-initiating subpopulations. In our study, we performed flow cytometry-based Hoechst 33342 staining to evaluate the existence of a MM population with stem-like features known as side population (SP) cells. SP cells exhibit substantial heterogeneity in MM cell lines and primary MM cells; express CD138 antigen in MM cell lines; display higher mRNA expression and functional activity of ABCG2 transporter; and have a higher proliferation index compared with non-SP cells. We observed evidence for clonogenic potential of SP cells, as well as the ability of SP cells to regenerate original population. Moreover, SP cells revealed higher tumorigenicity compared with non-SP cells. Importantly, lenalidomide decreased the percentage and clonogenicity of SP cells, and also induced phosphorylation changes in Akt, GSK-3α/ß, MEK1, c-Jun, p53, and p70S6K in SP cells. Adherence to bone marrow stromal cells (BMSCs) increased the percentage, viability, and proliferation potential of SP cells. Lenalidomide and thalidomide abrogated this stimulatory effect of BMSCs and significantly decreased the percentage of SP cells. Our studies demonstrate a novel mechanism of action for lenalidomide, namely targeting SP fraction, providing the framework for new therapeutic strategies targeting subpopulations of MM cells including presumptive stem cells.

Platelets actively sequester angiogenesis regulators.

Clinical trials with antiangiogenic agents have not been able to validate plasma or serum levels of angiogenesis regulators as reliable markers of cancer presence or therapeutic response. We recently reported that platelets contain numerous proteins that regulate angiogenesis. We now show that accumulation of angiogenesis regulators in platelets of animals bearing malignant tumors exceeds significantly their concentration in plasma or serum, as well as their levels in platelets from non-tumor-bearing animals. This process is selective, as platelets do not take up a proportional amount of other plasma proteins (eg, albumin), even though these may be present at higher concentrations. We also find that VEGF-enriched Matrigel pellets implanted subcutaneously into mice or the minute quantities of VEGF secreted by microscopic subcutaneous tumors (0.5-1 mm(3)) result in an elevation of VEGF levels in platelets, without any changes in its plasma levels. The profile of other angiogenesis regulatory proteins (eg, platelet-derived growth factor, basic fibroblast growth factor) sequestered by platelets also reflects the presence of tumors in vivo before they can be macroscopically evident. The ability of platelets to selectively take up angiogenesis regulators in cancer-bearing hosts may have implications for the diagnosis and management of many angiogenesis-related diseases and provide a guide for antiangiogenic therapies.

Identification of novel antigens with induced immune response in monoclonal gammopathy of undetermined significance.

The transformation from monoclonal gammopathy of undetermined significance (MGUS) to multiple myeloma (MM) is thought to be associated with changes in immune processes. We have therefore used serologic analysis of recombinant cDNA expression library to screen the sera of MGUS patients to identify tumor-associated antigens. A total of 10 antigens were identified, with specific antibody responses in MGUS. Responses appeared to be directed against intracellular proteins involved in cellular functions, such as apoptosis (SON, IFT57/HIPPI), DNA and RNA binding (ZNF292, GPATCH4), signal transduction regulators (AKAP11), transcriptional corepressor (IRF2BP2), developmental proteins (OFD1), and proteins of the ubiquitin-proteasome pathway (PSMC1). Importantly, the gene responsible for the oral-facial-digital type I syndrome (OFD1) had response in 6 of 29 (20.6%) MGUS patients but 0 of 11 newly diagnosed MM patients. Interestingly, 3 of 11 (27.2%) MM patients after autologous stem cell transplantations showed responses to OFD1. We have confirmed T-cell responses against OFD1 in MGUS and observed down-regulation of GLI1/PTCH1 and p-beta-catenin after OFD1 knock-down with specific siRNA, suggesting its functional role in the regulation of Hh and Wnt pathways. These findings demonstrate OFD1 as an important immune target and highlight its possible role in signal transduction and tumorigenesis in MGUS and MM.

Anti-tumor activity and signaling events triggered by the isothiocyanates, sulforaphane and phenethyl isothiocyanate, in multiple myeloma.

BACKGROUND: Isothiocyanates, a family of phytochemicals found in cruciferous vegetables, have cytotoxic effects against several types of tumor cells. Multiple myeloma is a fatal disease characterized by clonal proliferation of plasma cells in the bone marrow. The growing body of preclinical information on the anti-cancer activity of isothiocyanates led us to investigate their anti-myeloma properties. DESIGN AND METHODS: We evaluated the anti-myeloma activity of the isothiocyanates, sulforaphane and phenethyl isothiocyanate, on a panel of human myeloma cell lines as well as primary myeloma tumor cells. Cell viability, apoptosis, cell cycle alterations and cell proliferation were then analyzed in vitro and in a xenograft mouse model in vivo. The molecular sequelae of isothiocyanate treatment in multiple myeloma cells were evaluated by multiplex analyses using bead arrays and western blotting. RESULTS: We observed that sulforaphane and phenylethyl isothiocyanate have activity against myeloma cell lines and patients' myeloma cells both in vitro and in vivo using a myeloma xenograft mouse model. Isothiocyanates induced apoptotic death of myeloma cells; depletion of mitochondrial membrane potential; cleavage of PARP and caspases-3 and -9; as well as down-regulation of anti-apoptotic proteins including Mcl-1, X-IAP, c-IAP and survivin. Isothiocyanates induced G(2)/M cell cycle arrest accompanied by mitotic phosphorylation of histone H3. Multiplex analysis of phosphorylation of diverse components of signaling cascades revealed changes in MAPK activation; increased phosphorylation of c-jun and HSP27; as well as changes in the phosphorylation of Akt, and GSK3α/ß and p53. Isothiocyanates suppressed proliferation of myeloma cells alone and when co-cultured with HS-5 stromal cells. Sulforaphane and phenylethyl isothiocyanate enhanced the in vitro anti-myeloma activity of several conventional and novel therapies used in multiple myeloma. CONCLUSIONS: Our study shows that isothiocyanates have potent anti-myeloma activities and may enhance the activity of other anti-multiple myeloma agents. These results indicate that isothiocyanates may have therapeutic potential in multiple myeloma and provide the preclinical framework for future clinical studies of isothiocyanates in multiple myeloma.

Micronutrients attenuate progression of prostate cancer by elevating the endogenous inhibitor of angiogenesis, platelet factor-4.

BACKGROUND: Longstanding evidence implicates an inadequate diet as a key factor in the onset and progression of prostate cancer. The purpose herein was to discover, validate and characterize functional biomarkers of dietary supplementation capable of suppressing the course of prostate cancer in vivo. METHODS: The Lady transgenic mouse model that spontaneously develops prostate cancer received a diet supplemented with a micronutrient cocktail of vitamin E, selenium and lycopene ad libitum. A proteomic analysis was conducted to screen for serum biomarkers of this dietary supplementation. Candidate peptides were validated and identified by sequencing and analyzed for their presence within the prostates of all mice by immunohistochemistry. RESULTS: Dietary supplementation with the combined micronutrients significantly induced the expression of the megakaryocyte-specific inhibitor of angiogenesis, platelet factor-4 (P = 0.0025). This observation was made predominantly in mice lacking tumors and any manifestations associated with progressive disease beyond 37 weeks of life, at which time no survivors remained in the control group (P < 0.0001). While prostates of mice receiving standard chow were enlarged and burdened with poorly differentiated carcinoma, those of mice on the supplemented diet appeared normal. Immunohistochemical analysis revealed marked amplifications of both platelet binding and platelet factor-4 within the blood vessels of prostates from mice receiving micronutrients only. CONCLUSION: We present unprecedented data whereby these combined micronutrients effectively promotes tumor dormancy in early prostate cancer, following initiation mutations that may drive the angiogenesis-dependent response of the tumor, by inducing platelet factor-4 expression and concentrating it at the tumor endothelium through enhanced platelet binding.

Tumors stimulate platelet delivery of angiogenic factors in vivo: an unexpected benefit.

The interaction between platelets and the tumor microenvironment results in the modulation of angiogenesis, although the mechanisms governing this regulation remain unclear. This study explores the differences in the communication between wounded tissues and healthy, tumor-conditioned, and frozen platelets. Platelet-rich plasma obtained from healthy (PRP) or tumor-bearing (TPRP) mice was applied to dorsal, full-thickness wounds on diabetic mice. Wound healing was evaluated using macroscopic criteria and a staging system based on angiogenesis and stromal cell proliferation. Proteomic analysis was used to compare the levels of angiogenic proteins contained in the platelet preparations. TPRP-treated wounds reached 90% wound closure 5.6 to 9.5 days earlier than PRP-treated and nontreated wounds, respectively. TPRP induced a fourfold increase in stromal cell proliferation compared with nontreated wounds, and a 2.5-fold increase compared with PRP-treated wounds. TPRP induced the highest stimulation of angiogenesis with a fourfold increase compared with nontreated controls. On day 21, wounds treated with TPRP showed a typical architecture with thick collagen bundles. Although the levels of angiogenesis regulators detected via SELDI-ToF were similar between the PRP and TPRP treatment regimens, the enhanced healing capacity of TPRP suggests improved platelet delivery as indicated by frozen TPRP preparations that had lost most of their pro-angiogenic drive. In conclusion, these results show that intact tumor-conditioned platelets display an improved ability to deliver angiogenesis regulators to wounded tissues.

Direct transcriptional regulation of MDM2 by Fli-1.

The Ets transcription factor, Fli-1, has been shown to play a pivotal role in the induction and progression of Friend Murine Leukemia Virus (F-MuLV)-induced erythroleukemia, with its overexpression leading to erythroblast survival, proliferation, and inhibition of terminal differentiation. P53 inactivation is an additional genetic alteration that occurs in late-stage leukemic progression associated with in vivo and in vitro immortalization. Since p53 protein expression levels are low, to undetectable, in primary erythroleukemic cells that express elevated levels of Fli-1, we investigated the potential regulation of p53 by Fli-1. We assessed whether the overexpression of Fli-1 could partially regulate p53 via modulation of its well-established regulator, MDM2. In this paper, we demonstrate that the promoter of MDM2 contains a consensus binding site for Fli-1 that is bound by this transcription factor in vitro and in vivo, resulting in MDM2 transcriptional regulation. We further substantiate these observations in vivo by demonstrating a positive correlation in the expression of Fli-1 and MDM2, and a negative correlation with p53 in leukemic tissues obtained from mice with Friend Disease. These observations depict a significant function of Fli-1 overexpression in the indirect control of p53, evidently capable of leading to an increasingly aggressive erythroleukemic clone in vivo.

Phosphorylation status of c-Kit and Epo receptors, and the presence of wild-type p53 confer in vitro resistance of murine erythroleukemic cells to Celecoxib.

It is well established that selective COX-2 inhibitors exhibit potent effects against progression of select solid tumours. However, their effects on liquid tumours have not been fully established. By taking advantage of murine Friend Disease we have shown a strong antileukemic effect of celecoxib by determining novel in vitro targets. Western blot analyses revealed the expression of COX-2 in a panel of Friend Virus-transformed, splenic-derived primary erythroleukemic blasts and established cell lines generated in our laboratory. We have shown that celecoxib at concentrations as low as 20 microM significantly suppresses proliferation of the selected murine erythroleukemia cell line HB60-5. The greatest proliferative inhibition was seen at 40 microM of celecoxib, resulting in apoptosis. Our results also demonstrate that treatment of the established murine erythroleukemia cell line HB60-5 with celecoxib results in suppression of c-Kit and erythropoietin receptor (Epo-R) phosphorylation resulting in apoptosis, likely through decreased levels of survival factors. However, upon overexpression of c-Kit alone in these cells a significant increase in survival and twofold increase in proliferation in the presence of celecoxib were observed (P < 0.05). Finally, since responsiveness of our murine erythroleukemia cell lines to celecoxib is above the reported physiologically achievable levels in vivo, we have provided in vitro evidence to suggest that reduced sensitivity of erythroleukemic cells to lower doses of celecoxib may be a consequence of the loss of wild-type p53. These findings are pivotal in addressing potential discrepancies associated with sensitivity of murine erythroleukemic cells to celecoxib in vitro versus in vivo.

Vascular endothelial growth factor--a positive and negative regulator of tumor growth.

Over the past decade, the well-documented role of vascular endothelial growth factor (VEGF) in tumor angiogenesis has led it to become one of the leading therapeutic targets for the treatment of cancer. Emerging evidence from genetically modified animal models, however, suggests that elevated levels of VEGF, or a proangiogenic phenotype, may impede, rather than promote, early tumor development and progression. For example, hypermorph VEGF transgenic mice display delayed progression of a retroviral-induced murine leukemia, and knockdown of VEGF expression within the myeloid compartment accelerates tumor progression. Several mechanisms have been proposed to explain this paradox, whereby VEGF induces changes within the hematopoietic compartment and tumor microenvironment through recruitment of tumor inhibitory monocytic cells and the negative regulation of tumor angiogenesis. Thus, it is apparent that the levels of VEGF expression in both tumor and nontumor tissues, as well as the context and timing of its modulation relative to cancer induction, play an important role in determining the effects of VEGF expression on tumorigenicity. In light of these recent findings, the various mechanisms underlying the negative role of VEGF during early tumor development, progression, and metastasis will be discussed.

Platelet-associated PF-4 as a biomarker of early tumor growth.

Early tumor detection and intervention are important determinants of survival in patients with cancer. We have recently reported that the "platelet angiogenesis proteome" may be used to detect microscopic tumors in mice. We now present evidence that changes in platelet-associated platelet factor-4 (PF-4) detect malignant growth across a spectrum of human cancers in mice. A deregulated expression of an 8206-Da protein was observed by surfaceenhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-ToF MS) proteomic comparison of platelets from normal and tumor-bearing mice. The differentially expressed protein was identified as PF-4 by tandem mass spectrometry and ProteinChip immunoassay using anti-PF-4 antibody. The platelet-associated PF-4 appeared to be up-regulated in early growth of human liposarcoma, mammary adenocarcinoma, and osteosarcoma. A 120-day follow-up study of liposarcoma revealed a sustained 2-fold or higher increase of platelet-associated PF-4 at 19, 30, and 120 days. In contrast, only an insignificant change of PF-4 was observed in the plasma of mice bearing the different human tumor xenografts, and throughout the 120 days of the liposarcoma study. We conclude that platelet-associated PF-4, but not its plasma counterpart, may represent a potential biomarker of early tumor presence.

Enhanced natural-killer cell and erythropoietic activities in VEGF-A-overexpressing mice delay F-MuLV-induced erythroleukemia.

We have previously reported that VEGF-A, in combination with MCP-5, contributes to leukemia progression within the splenic microenvironment of mice infected with F-MuLV. To study the influence of constitutively elevated VEGF-A levels on the progression of erythroleukemia, mice heterozygous for a VEGF-A "hypermorphic" allele (Vegfhi/+) were inoculated with F-MuLV. Unexpectedly, a significant delay in erythroleukemia was observed in Vegfhi/+ mice when compared with wild-type controls. These results suggested an altered physiologic response arising from elevated VEGF-A levels that decelerated erythroleukemic progression. Characterization of hematopoiesis in Vegfhi/+ spleens showed a higher natural killer cell activity, elevated B cells, and a decrease in T-cell number. Furthermore, higher erythroid progenitors (ie, CD34+, CD36+, and Ter119+ cells) were evident in the bone marrow, spleen, and peripheral blood of Vegfhi/+ mice. The CFU-E levels were significantly elevated in Vegfhi/+ bone marrow cultures, and this elevation was blocked by a neutralizing antibody to VEGF-A receptor (VEGFR-2). Moreover, erythroleukemic mice were treated with recombinant erythropoietin and, similar to diseased Vegfhi/+ mice, showed a delay in disease progression. We propose that a compensatory erythropoietic response combined with increased natural killer (NK) cell activity account for the extended survival of erythroleukemic, Vegfhi/+ mice.

Effect of serum and antioxidants on the immunogenicity of protein kinase C-activated chronic lymphocytic leukemia cells.

Since the intrinsically poor immunogenicity of chronic lymphocytic leukemia (CLL) cells might be a key factor in allowing them to avoid immune control mechanisms, the development of methods to enhance CLL cell immunogenicity might lead to improved disease control. The ability of CLL cells to stimulate T cells was increased significantly by the protein kinase C (PKC) agonist phorbol myristic acetate (PMA). However, under serum-free conditions, PMA-activated CLL cells died within 48 hours. Antioxidants, such as 2-mercaptoethanol (2-ME), or fetal calf serum could prevent the death of these cells but caused them to enter distinct states of differentiation. In the presence of 2-ME, PMA-activated CLL cells extended dendritic-like protrusions and exhibited increased T-cell stimulatory capacity. In the presence of serum, PMA-activated CLL cells developed fewer dendrites, made less IL-10 and more IL-12 p40 mRNA transcripts, and showed an increased capacity to induce IFN-gamma production by T cells. The effects of serum on the promotion of type 1 immune responses by phorbol ester-activated CLL cells were dominant and correlated with activation of the NF-kappaB signaling pathway. Other PKC agonists, such as Bryostatin-1 and a synthetic Bryostatin analog (Picolog), had similar effects on CLL cells. The observation that CLL cells can acquire features of dendritic cells that promote type 1 immunity may find clinical application in immunotherapeutic strategies for this disease.