Annalisa Pezzolo

Targeting Liposomal Chemotherapy via Both Tumor Cell–Specific and Tumor Vasculature–Specific Ligands Potentiates Therapeutic Efficacy

Neuroblastoma, the most common solid tumor of infancy derived from the sympathetic nervous system, continues to present a formidable clinical challenge. Sterically stabilized immunoliposomes (SIL) have been shown to enhance the selective localization of entrapped drugs to solid tumors, with improvements in therapeutic indices. We showed that SIL loaded with doxorubicin (DXR) and targeted to the disialoganglioside receptor GD(2) [aGD(2)-SIL(DXR)] led to a selective inhibition of the metastatic growth of experimental models of human neuroblastoma. By coupling NGR peptides that target the angiogenic endothelial cell marker aminopeptidase N to the surface of DXR-loaded liposomes [NGR-SL(DXR)], we obtained tumor regression, pronounced destruction of the tumor vasculature, and prolonged survival of orthotopic neuroblastoma xenografts. Here, we showed good liposome stability, long circulation times, and enhanced time-dependent tumor accumulation of both the carrier and the drug. Antivascular effects against animal models of lung and ovarian cancer were shown for formulations of NGR-SL(DXR). In the chick embryo chorioallantoic assay, NGR-SL(DXR) substantially reduced the angiogenic potential of various neuroblastoma xenografts, with synergistic inhibition observed for the combination of NGR-SL(DXR) with aGD(2)-SIL(DXR). A significant improvement in antitumor effects was seen in neuroblastoma-bearing animal models when treated with the combined formulations compared with control mice or mice treated with either tumor- or vascular-targeted liposomal formulations, administered separately. The combined treatment resulted in a dramatic inhibition of tumor endothelial cell density. Long-term survivors were obtained only in animals treated with the combined tumor- and vascular-targeted formulations, confirming the pivotal role of combination therapies in treating aggressive metastatic neuroblastoma.

Tumor Origin of Endothelial Cells in Human Neuroblastoma

PURPOSE Malignant cells are genetically unstable and prone to develop chemotherapy resistance, whereas tumor vasculature is usually of host origin and genetically stable. Tumor endothelial microvessels attract interest as therapeutic targets, but their genetic instability would curtail such approach. Here, we have investigated the tumor origin of endothelial microvessels in human neuroblastoma (NB). MATERIALS AND METHODS Paraffin-embedded tissue sections from 10 MYCN-amplified tumors (six stage 4, three stage 3, and one stage 1) were studied. Endothelial cells (ECs) were detected by immunofluorescent staining for CD31 or CD105, and MYCN amplification was detected using fluorescence in situ hybridization (FISH). In xenografts of the HTLA-230 human NB cell line, human ECs were detected by CD31 staining, mouse ECs were detected by CD34 staining, and MYCN amplification and murine DNA were detected using FISH. RESULTS MYCN-amplified ECs formed approximately 70% of tumor endothelial microvessels in two stage 4 tumors and 20% in one stage 3 tumor. Similar results were obtained after EC labeling with CD31 or CD105. Staining for alpha-smooth muscle actin in combination with MYCN FISH demonstrated that tumor-derived ECs were coated with pericytes. These vessels were functional because they contained RBCs. Approximately 70% of endothelial vessels from HTLA-230 xenografts stained for human CD31, but not murine CD34, and displayed MYCN amplification, thus proving their tumor origin. CONCLUSION NB-associated endothelial microvessels can originate from tumor cells, and this finding challenges the tenet that tumor vasculature is genetically stable. The possibility that NB-derived ECs are chemotherapy resistant warrants further investigation.

Presence of telomeric and subtelomeric sequences at the fusion points of ring chromosomes indicates that the ring syndrome is caused by ring instability

In situ hybridization of a telomeric (TTA-GGG)n sequence to metaphases from three cases of ring chromosome, involving respectively chromosomes 4, 16, and 20, showed the presence of the cognate sequences in all three rings. To investigate whether these ring chromosomes originated by telomere-telomere fusion, we determined, by in situ hybridization, whether telomere-associated sequences and/or specific distal sequences were still present in the ring chromosomes. The finding that these sequences were preserved in all the ring chromosomes strongly indicates that they originated by telomere-telomere fusion. All three subjects carrying the ring chromosomes are affected by the so-called ring syndrome, with failure to thrive, minor dysmorphic signs and no major anomalies. The r(4) patient has the ring in mosaic form with a normal cell line and has normal intelligence. The r(16) and the r(20) patients have moderate mental retardation and suffer from seizures. We conclude that the ring syndrome, even in its more severe manifestation, is caused by ring chromosome instability.

Proteome Profiling of Neuroblastoma-Derived Exosomes Reveal the Expression of Proteins Potentially Involved in Tumor Progression

Neuroblastoma (NB) is the most common extracranial solid tumor in childhood, with grim prognosis in a half of patients. Exosomes are nanometer-sized membrane vesicles derived from the multivesicular bodies (MVBs) of the endocytic pathway and released by normal and neoplastic cells. Tumor-derived exosomes have been shown in different model systems to carry molecules that promote cancer growth and dissemination. In this respect, we have here performed the first characterization and proteomic analysis of exosomes isolated from human NB cell lines by filtration and ultracentrifugation. Electron microscopy demonstrated that NB-derived exosomes exhibited the characteristic cup-shaped morphology. Dynamic light scattering studies showed a bell-shaped curve and a polydispersity factor consistent with those of exosomes. Zeta potential values suggested a good nanoparticle stability. We performed proteomic analysis of NB-derived exosomes by two dimension liquid chromatography separation and mass spectrometry analyses using the multidimensional protein identification technology strategy. We found that the large majority of the proteins identified in NB derived exosomes are present in Exocarta database including tetraspanins, fibronectin, heat shock proteins, MVB proteins, cytoskeleton-related proteins, prominin-1 (CD133), basigin (CD147) and B7-H3 (CD276). Expression of the CD9, CD63 and CD81 tetraspanins, fibronectin, CD133, CD147 and CD276 was validated by flow cytometry. Noteworthy, flow cytometric analysis showed that NB-derived exosomes expressed the GD2 disialoganglioside, the most specific marker of NB. In conclusion, this study shows that NB-derived exosomes express a discrete set of molecules involved in defense response, cell differentiation, cell proliferation and regulation of other important biological process. Thus, NB-derived exosomes may play an important role in the modulation of tumor microenvironment and represent potential tumor biomarkers.

Bronchial Airway Epithelial Cell Damage Following Exposure to Cigarette Smoke Includes Disassembly of Tight Junction Components Mediated by the Extracellular Signal-Regulated Kinase 1/2 Pathway

BACKGROUND Through a variety of biochemical mechanisms, cigarette smoke (CS) may damage airway epithelium, altering its normal structure and function. Injury to epithelium may include changes in tight junction (TJ) integrity with impairment of epithelial barrier function. METHODS AND RESULTS To study the effect of the exposure to CS condensate (CSC) on TJ integrity, two human bronchial epithelial cell lines (HBECs), BEAS-2B and 16HBE14o-, were used. Exposure of the two HBECs to CSC resulted in a time-dependent and concentration-dependent disassembly of TJs, which were already detectable at 24 h at all the CSC concentrations tested (5%, 10%, and 20%), associated with changes in cell shape, suggesting cell damage. However, a significant inhibition of cell growth and an increase in DNA fragmentation were detected only at the highest CSC concentration tested (20%) at 48 and 72 h, respectively. The involvement of epidermal growth factor receptor (EGFR)-extracellular signal-regulated kinase (ERK) 1/2 cascade in CSC-induced damage was shown by the observation that exposure to CSC (5%) induced a marked phosphorylation of ERK1/2, already detectable after 5-min incubation and confirmed by the demonstration that not only ERK1/2 phosphorylation but also CSC-induced TJ disassembly and DNA fragmentation were partially inhibited by a mitogen-activated protein kinase kinase inhibitor (U0126) and completely blocked by a EGFR inhibitor (AG1478). CONCLUSION CSC-induced damage to airway epithelium includes disassembly of TJs, modulated through the EGFR-ERK1/2 signaling pathway.

Combined Therapeutic Effects of Vinblastine and Rapamycin on Human Neuroblastoma Growth, Apoptosis, and Angiogenesis

Purpose: Vinblastine and rapamycin displayed synergistic inhibition of human neuroblastoma-related angiogenesis. Here, we studied the antitumor activity of vinblastine and rapamycin against human neuroblastoma. Experimental Design: Cell proliferation, cell cycle progression, and apoptosis were evaluated by measuring 3H-thymidine incorporation, bromodeoxyuridine uptake, and phosphatidylserine exposure, respectively. The in vivo sensitivity of neuroblastoma cells to vinblastine and rapamycin was determined in orthotopic neuroblastoma-engrafted mice. Angiogenesis was assessed by the chick embryo chorioallantoic membrane assay. Results: Each compound alone was able to induce a dose-dependent significant inhibition of cell proliferation, with a dramatically enhanced antiproliferative effect for the drugs used in combination. A marked G2-M cell cycle arrest with a nearly complete depletion of S phase was associated. The combined treatment triggered an increased apoptosis compared with either drug tested alone. A significant inhibition of tumor growth and microvessel area was obtained in neuroblastoma-bearing mice when treated with vinblastine or rapamycin alone, and a more dramatic effect with the combined treatment, compared with control mice. The therapeutic effectiveness, expressed as increased life span, was statistically improved by the combined therapy, compared with mice treated with either drug tested separately. Histologic evaluation of primary tumors showed that the combined treatment inhibited proliferation and angiogenesis and induced apoptosis. Combined treatment of neuroblastoma cells and neuroblastoma-bearing mice with vinblastine and rapamycin induced the down-modulation of both vascular endothelial growth factor production and vascular endothelial growth factor receptor 2 expression. In the chorioallantoic membrane assay, angiogenesis induced by human neuroblastoma biopsy specimens was significantly inhibited by vinblastine and rapamycin. Conclusions: These results may be relevant to design new therapeutic strategies against neuroblastoma.

The IL-12Rβ2 gene functions as a tumor suppressor in human B cell malignancies

The IL-12Rβ2 gene is expressed in human mature B cell subsets but not in transformed B cell lines. Silencing of this gene may be advantageous to neoplastic B cells. Our objective was to investigate the mechanism(s) and the functional consequence(s) of IL-12Rβ2 gene silencing in primary B cell tumors and transformed B cell lines. Purified tumor cells from 41 patients with different chronic B cell lymphoproliferative disorders, representing the counterparts of the major mature human B cell subsets, tested negative for IL-12Rβ2 gene expression. Hypermethylation of a CpG island in the noncoding exon 1 was associated with silencing of this gene in malignant B cells. Treatment with the DNA methyltransferase inhibitor 5-Aza-2′-deoxycytidine restored IL-12Rβ2 mRNA expression in primary neoplastic B cells that underwent apoptosis following exposure to human recombinant IL-12 (hrIL-12). hrIL-12 inhibited proliferation and increased the apoptotic rate of IL-12Rβ2–transfected B cell lines in vitro. Finally, hrIL-12 strongly reduced the tumorigenicity of IL-12Rβ2–transfected Burkitt lymphoma RAJI cells in SCID-NOD mice through antiproliferative and proapoptotic effects, coupled with neoangiogenesis inhibition related to human IFN-γ–independent induction of hMig/CXCL9. The IL-12Rβ2 gene acts as tumor suppressor in chronic B cell malignancies, and IL-12 exerts direct antitumor effects on IL-12Rβ2–expressing neoplastic B cells.

Endothelial and smooth muscle cells from abdominal aortic aneurysm have increased oxidative stress and telomere attrition.

Background Abdominal aortic aneurysm (AAA) is a complex multi-factorial disease with life-threatening complications. AAA is typically asymptomatic and its rupture is associated with high mortality rate. Both environmental and genetic risk factors are involved in AAA pathogenesis. Aim of this study was to investigate telomere length (TL) and oxidative DNA damage in paired blood lymphocytes, aortic endothelial cells (EC), vascular smooth muscle cells (VSMC), and epidermal cells from patients with AAA in comparison with matched controls. Methods TL was assessed using a modification of quantitative (Q)-FISH in combination with immunofluorescence for CD31 or α-smooth muscle actin to detect EC and VSMC, respectively. Oxidative DNA damage was investigated by immunofluorescence staining for 7, 8-dihydro-8-oxo-2′-deoxyguanosine (8-oxo-dG). Results and Conclusions Telomeres were found to be significantly shortened in EC, VSMC, keratinocytes and blood lymphocytes from AAA patients compared to matched controls. 8-oxo-dG immunoreactivity, indicative of oxidative DNA damage, was detected at higher levels in all of the above cell types from AAA patients compared to matched controls. Increased DNA double strand breaks were detected in AAA patients vs controls by nuclear staining for γ-H2AX histone. There was statistically significant inverse correlation between TL and accumulation of oxidative DNA damage in blood lymphocytes from AAA patients. This study shows for the first time that EC and VSMC from AAA have shortened telomeres and oxidative DNA damage. Similar findings were obtained with circulating lymphocytes and keratinocytes, indicating the systemic nature of the disease. Potential translational implications of these findings are discussed.

The Combined Therapeutic Effects of Bortezomib and Fenretinide on Neuroblastoma Cells Involve Endoplasmic Reticulum Stress Response

Purpose: The proteasome inhibitor bortezomib inhibited cell growth and angiogenesis in neuroblastoma. Bortezomib has been shown to induce synergistic activity when combined with other antineoplastic agents. Here we have investigated the antitumor activity of bortezomib in combination with fenretinide, a synthetic retinoid, against neuroblastoma cells. Experimental Design: Different neuroblastoma cell lines were tested for sensitivity to bortezomib and fenretinide, given alone or in different dose-dependent and time-dependent combination schedules. Cell proliferation, cell viability, and apoptosis were evaluated by measuring 3H-thymidine incorporation, trypan blue staining, DNA fragmentation, and western blot analysis. Angiogenesis was assessed by the chick embryo chorioallantoic membrane assay. An orthotopic neuroblastoma mouse model was used to examine in vivo sensitivity. Results: Each compound alone was able to induce a dose-dependent inhibition of cell proliferation, with a significant enhanced antiproliferative effect for the drugs used in combination. This inhibition was characterized by marked G2-M and G1 cell cycle arrest with nearly complete depletion of S phase. Bortezomib and fenretinide in association triggered an increased apoptosis through activation of specific genes of the endoplasmic reticulum stress compared with either drug tested alone. Tumor-bearing mice treated with bortezomib plus fenretinide lived statistically significantly longer than mice treated with each drug alone. Histologic evaluation and chorioallantoic membrane analysis of primary tumors showed that the combined therapeutic activity of bortezomib and fenretinide rested upon antitumor and antiangiogenic mechanisms. Conclusions: These findings provide the rationale for the development of a new therapeutic strategy for neuroblastoma based on this pharmacologic combination.

Human NK cell infusions prolong survival of metastatic human neuroblastoma-bearing NOD/scid mice

AimSeveral lines of evidence suggest that NK cell immunotherapy may represent a successful approach in neuroblastoma (NB) patients refractory to conventional therapy. However, homing properties, safety and therapeutic efficacy of NK cell infusions need to be evaluated in a suitable preclinical murine NB model.Materials and methodsHere, the therapeutic efficacy of NK cell infusions in the presence or absence of NK-activating cytokines have been evaluated in a NB metastatic model set up in NOD/scid mice, that display reduced functional activity of endogenous NK cells.ResultsIn NOD/scid mice the injected NB cells rapidly reached all the typical sites of metastatization, including bone marrow. Infusion of polyclonal IL2-activated NK cells was followed by dissemination of these cells into various tissues including those colonized by metastatic NB cells. The early repeated injection of IL2-activated NK cells in NB-bearing NOD/scid mice significantly increased the mean survival time, which was associated with a reduced bone marrow infiltration. The therapeutic effect was further enhanced by low doses of human recombinant IL2 or IL15.ConclusionOur results indicate that NK-based adoptive immunotherapy can represent a valuable adjuvant in the treatment of properly selected NB patients presenting with metastatic disease, if performed in a minimal residual disease setting.