IL-27 attenuates IL-23 mediated inflammatory arthritis

Interleukin 27 has both pro-inflammatory and anti-inflammatory properties in autoimmunity. The anti-inflammatory effects of IL-27 are linked with inhibition of Th17 differentiation but the IL-27 effect on myeloid cells is less studied. Herein we demonstrate that IL-27 inhibits IL-23-induced inflammation associated not only with Th17 cells but also with myeloid cell infiltration in the joints and splenic myeloid populations of CD11b⁺ GR1⁺ and CD3^-CD11b⁺CD11c^-GR1^- cells. The IL-27 anti-inflammatory response was associated with reduced levels of myeloid cells in the spleen and bone marrow. Overall, our data demonstrate that IL-27 has an immunosuppressive role that affects IL-23-dependent myelopoiesis in the bone marrow and its progression to inflammatory arthritis and plays a crucial role in controlling IL-23 driven joint inflammation by negatively regulating the expansion of myeloid cell subsets.

Combined immunodeficiency due to a mutation in the γ1 subunit of the coat protein I complex

The coat protein I (COPI) complex mediates retrograde trafficking from the Golgi to the endoplasmic reticulum (ER). Five siblings with persistent bacterial and viral infections and defective humoral and cellular immunity had a homozygous p.K652E mutation in the γ1 subunit of COPI (γ1-COP). The mutation disrupts COPI binding to the KDEL receptor and impairs the retrieval of KDEL-bearing chaperones from the Golgi to the ER. Homozygous Copg1K652E mice had increased ER stress in activated T and B cells, poor antibody responses, and normal numbers of T cells that proliferated normally, but underwent increased apoptosis upon activation. Exposure of the mutants to pet store mice caused weight loss, lymphopenia, and defective T cell proliferation that recapitulated the findings in the patients. The ER stress-relieving agent tauroursodeoxycholic acid corrected the immune defects of the mutants and reversed the phenotype they acquired following exposure to pet store mice. This study establishes the role of γ1-COP in the ER retrieval of KDEL-bearing chaperones and thereby the importance of ER homeostasis in adaptive immunity.

Aneurysm of the ascending aorta in systemic lupus erythematosus: Case report and review of the literature

Cardiovascular manifestations in patients with systemic lupus erythematosus (SLE) are common, but aortic aneurysm formation is rare. We present a 63-year-old male SLE patient with a two-year history of skin lesions, leucopenia, pericarditis, mitral valve vegetations consistent with Liebman-Sacks endocarditis, and an aneurysm of the ascending aorta, which was successfully repaired surgically. Histologic examination of the aneurysm showed medial cystic degeneration, smooth muscle necrosis, and mild adventitial perivascular lymphocytic aggregates. This histology is typical of thoracic aneurysms that carry a high risk for aortic dissection and patient death. The case highlights the importance of early detection and treatment of thoracic aortic aneurysms in patients with SLE.

Insight into the incidence of acute aortic dissection in the German region of Berlin and Brandenburg

BACKGROUND

Stanford acute type A aortic dissection (ATAAD) is a potentially lethal condition. Epidemiology studies show a statistical incidence in Europe of approximately 2-16 cases/100,000 inhabitants/year. In Germany, the estimated incidence (here subsumed under "thoracic aortic dissection" with 4.63 cases/100,000 inhabitants/year) is mainly extracted from medical death certificates by the German Federal Statistical Office. The prehospital incidence of ATAAD deaths is largely unknown. Since patients often die in the pre-hospital setting, the incidence of ATAAD is therefore likely to be higher than current estimates.

MATERIAL AND METHODS

For the period from 2010 to 2014, we retrospectively analyzed all in-hospital ATAAD data from two of the largest cardiac surgical centers that treat ATAAD in the Berlin-Brandenburg region. In addition, autopsy reports of all forensic medicine institutes and of one large pathological provider in the region were analyzed to identify additional non-hospitalized ATAAD patients. Based on these findings, the regional incidence of ATAAD was calculated.

RESULTS

In addition to in-hospital ATAAD patients (n=405), we identified additional 145 lethal ATAAD cases among 14,201 autopsy reports. The total of 550 ATAAD cases led to an estimated incidence of 11.9 cases/100,000 inhabitants/year for the whole Berlin-Brandenburg region. Arterial hypertension, pre-existing aortic dilatation, and hereditary connective tissue disorder were found in, respectively, 62.7%, 10%, and 1.8% of patients.

CONCLUSION

ATAAD is more frequent than previously reported. Our results show that when patients who die outside of cardiac surgery centers are included, the incidence of ATAAD significantly exceeds the rate reported by the Federal Statistical Office.

[Mortui vivos docent : The dead teach the living]

There are considerable similarities and intersections between forensic medicine and emergency medicine. This applies especially to frustraneously resuscitated patients or other lethal clinical courses of traumatized patients who are subject to latter forensic autopsy. Cooperation between departments of emergency and forensic medicine not only has emergency medical training potential, but also the possibility of retrospective evaluation of medical emergency measures - both in individual cases and with regard to epidemiological aspects. In particular, the widespread registration of autopsied pre-hospital trauma deaths that occurred despite on-scene resuscitation attempts is useful. The pre-hospital situation represents a hotspot, but also a blind spot in the overall trauma mortality. In recent clinical registers, preclinical deaths go mostly unrecorded, despite the undisputed benefits of clinical registers.

Carney triad, SDH-deficient tumors, and Sdhb+/- mice share abnormal mitochondria

Carney triad (CTr) describes the association of paragangliomas (PGL), pulmonary chondromas, and gastrointestinal (GI) stromal tumors (GISTs) with a variety of other lesions, including pheochromocytomas and adrenocortical tumors. The gene(s) that cause CTr remain(s) unknown. PGL and GISTs may be caused by loss-of-function mutations in succinate dehydrogenase (SDH) (a condition known as Carney-Stratakis syndrome (CSS)). Mitochondrial structure and function are abnormal in tissues that carry SDH defects, but they have not been studied in CTr. For the present study, we examined mitochondrial structure in human tumors and GI tissue (GIT) of mice with SDH deficiency. Tissues from 16 CTr tumors (n=12), those with isolated GIST (n=1), and those with CSS caused by SDHC (n=1) and SDHD (n=2) mutations were studied by electron microscopy (EM). Samples of GIT from mice with a heterozygous deletion in Sdhb (Sdhb(+) (/-), n=4) were also studied by EM. CTr patients presented with mostly epithelioid GISTs that were characterized by plump cells containing a centrally located, round nucleus and prominent nucleoli; these changes were almost identical to those seen in the GISTs of patients with SDH. In tumor cells from patients, regardless of diagnosis or tumor type, cytoplasm contained an increased number of mitochondria with a 'hypoxic' phenotype: mitochondria were devoid of cristae, exhibited structural abnormalities, and were of variable size. Occasionally, mitochondria were small and round; rarely, they were thin and elongated with tubular cristae. Many mitochondria exhibited amorphous fluffy material with membranous whorls or cystic structures. A similar mitochondrial hypoxic phenotype was seen in Sdhb(+) (/-) mice. We concluded that tissues from SDH-deficient tumors, those from mouse GIT, and those from CTr tumors shared identical abnormalities in mitochondrial structure and other features. Thus, the still-elusive CTr defect(s) is(are) likely to affect mitochondrial function, just like germline SDH-deficiency does.

Intracellular activation of complement 3 mediates intestinal tissue damage during mesenteric ischemia (INC1P.356)

Ischemia of the intestine followed by reperfusion leads to significant local and remote organ injury (IRI) attributed to inflammatory elements acting during the reperfusion phase. Whether ischemia contributes to IRI has not been addressed. Careful evaluation of intestinal tissue following ischemia we noticed significant local injury, which was associated by increased production of complement 3 (C3) by intestinal epithelial cells. C3-deficient mice failed to exhibit similar injury and while cobra venom factor pre-treatment, which depleted all complement in the circulation, eliminated all IRI, but it failed to mitigate injury during the ischemia phase. C3 was activated within the epithelial cells during ischemia as indicated by immunocytochemistry and Caco2 (colon epithelial cancer cells) produced C3a after LPS stimulation. Production of C3a was decreased in the presence of cathepsin inhibitors. In conclusion, intestinal epithelial cells when subjected to ischemia can produce and activate C3 and initiate intestinal damage, which is amplified during the reperfusion phase.

Radiation therapy in management of sporadic and neurofibromatosis type 1-associated malignant peripheral nerve sheath tumors

INTRODUCTION

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive soft tissue sarcomas in which complete surgical resection is the mainstay of therapy. However, the recurrence rate is high and few options remain for refractory or metastatic MPNST. This study examines the outcomes of adjuvant radiation therapy in MPNST in patients with and without neurofibromatosis type 1 (NF1) and reviews the literature on use of radiation for MPNST.

METHODS

A retrospective review of 33 MPNST patients between 1990 and 2012 evaluated at the NIH. All diagnoses were pathologically confirmed at the NCI. Clinical presentation, treatment, and survival were analyzed.

RESULTS

Thirty-three patients were included 18 NF1-associated, 15 sporadic tumors. Tumor location included extremity (58%), trunk (36%), and head/neck (6%). Histologic grade showed 25 high-grade tumors compared to 7 low-grade tumors. Twenty patients were treated with radiation therapy (median total dose of 58.5 Gy with 1.8 Gy/fraction). A median survival of all patients was 46.5 months and 43.7% overall 5-year survival. Prognostic factors include extent of resection, tumor location, and histology grade. Radiation was not found to be a prognostic factor for overall survival.

CONCLUSION

This study is consistent with previous studies regarding the role of radiation in the management of MPNST. Prospective evaluation of adjuvant radiation will allow to more fully define the role of radiation in MPNST.

Role of IL-17 in intestinal ischemia-reperfusion injury. (MUC2P.829)

Background: Ischemia-reperfusion injury (IRI) to the small intestine following clamping of the superior mesenteric artery (SMA) results in an intense local inflammatory response characterized by neutrophil infiltration and villous damage. IL-17A is a cytokine expressed by a variety of cells in response to inflammatory cytokines that are released following tissue injury and/or inflammation. IL-17A induces epithelial cells to secrete neutrophil chemoattractants, such as CXCL2. The cytokine IL-23, which can be produced by epithelial cells, plays an important role in IL-17A production. Objective: To test the hypothesis that IL-17A is critical for intestinal damage following IRI. Materials and Methods: IRI was induced in mice by SMA clamping. IL-17A deficient (Il17a-/-) and IL-23R deficient (Il23r-/-) mice. Intestinal injury was evaluated by Chiu scores of jejunal histological sections. Results: IRI was significantly less in both Il17a-/- mice and Il23r/- mice than in WT controls. We also found that pretreatment of WT mice with neutralizing antibody to IL-17A or IL-23 resulted in significant decrease in IRI compared to mice treated with isotype control antibody. Conclusions: These results indicate that IL-17A plays a critical role in IRI. They also suggest that IL-23 contributes to IRI, possibly by promoting IL-17A production.

Lymphangitic retroperitoneal carcinomatosis occurring from metastatic sarcomatoid chromophobe renal cell carcinoma

A 45-year-old man with left renal mass underwent nephrectomy to reveal a 20-cm tumor diagnosed as sarcomatoid chromophobe renal cell carcinoma. Lymph node metastasis of chromophobe and sarcomatoid components, disseminated tumor in retroperitoneal fat, lymphatic vessels, and perirenal adipose tissue in lymphangitic carcinomatosis pattern were identified. Chromophobe epithelial cells were positive for epithelial membrane antigen, c-Kit, and cytokeratin 7; sarcomatoid cells were positive for CD10 and smooth muscle antigen with high proliferation index. Chromophobe epithelial cells had loss of heterozygosity in chromosomes 1p and 1q, whereas sarcomatoid cells had loss of heterozygosity in 3p, 1p, and 1q. In conclusion, sarcomatoid chromophobe renal cell carcinoma has aggressive biologic behavior and potential to metastasize in unusual patterns.

LPS-induced effects on angiotensin I-converting enzyme expression and shedding in human pulmonary microvascular endothelial cells

Angiotensin I-converting enzyme (kininase II, ACE, and CD143) availability is a determinant of local angiotensin and kinin concentrations and their physiological actions. Until now, it is unclear whether the decrease of pulmonary ACE activity in sepsis-described in clinical studies-is due to an enzyme compensatory downregulation (reduced ACE-mRNA expression) to shedding of ACE or endothelial damage. To address these questions, ACE distribution under septic conditions was studied in vitro by treating pulmonary microvascular endothelial cells (HPMEC) and human umbilical vein endothelial cells (HUVEC) with lipopolysaccharide from Escherichia coli (LPS). Primary isolated HUVEC and HPMEC were compared by detecting ACE activity, membrane-bound ACE, as well as shedding and mRNA production of ACE with and without LPS (1 ng/ml-1 μg/ml). ACE mRNA expression was detected by real-time PCR, and shedded ACE was measured in cell culture supernatant by ELISA. Additionally, membrane-bound protein expression was investigated by immunohistochemistry in situ. In septic ARDS, the distribution of ACE protein was significantly reduced in all lung endothelial cells (p<0.001). After stimulation with LPS, cultivated HPMEC showed more markedly than HUVEC, a concentration-dependent reduction of ACE protein expression compared to the respective untreated controls. Real-time PCR demonstrated a reduced ACE mRNA expression after LPS stimulation, predominantly in HPMEC. Specifically, in HPMEC, a concentration-dependent increase of shedded ACE was shown 24 h after LPS treatment. HPMEC cultures are an apt model for the investigation of pulmonary ACE expression in sepsis. This study suggests that reduced pulmonary microvascular endothelial ACE expression in septic ARDS is caused by two processes: (initial) increased shedding of ACE accompanied by a compensatory downregulation of ACE-mRNA and membrane-bound protein expression.

The influence of DNA repair on neurological degeneration, cachexia, skin cancer and internal neoplasms: autopsy report of four xeroderma pigmentosum patients (XP-A, XP-C and XP-D)

Background

To investigate the association of DNA nucleotide excision repair (NER) defects with neurological degeneration, cachexia and cancer, we performed autopsies on 4 adult xeroderma pigmentosum (XP) patients with different clinical features and defects in NER complementation groups XP-A, XP-C or XP-D.

Results

The XP-A (XP12BE) and XP-D (XP18BE) patients exhibited progressive neurological deterioration with sensorineural hearing loss. The clinical spectrum encompassed severe cachexia in the XP-A (XP12BE) patient, numerous skin cancers in the XP-A and two XP-C (XP24BE and XP1BE) patients and only few skin cancers in the XP-D patient. Two XP-C patients developed internal neoplasms including glioblastoma in XP24BE and uterine adenocarcinoma in XP1BE. At autopsy, the brains of the 44 yr XP-A and the 45 yr XP-D patients were profoundly atrophic and characterized microscopically by diffuse neuronal loss, myelin pallor and gliosis. Unlike the XP-A patient, the XP-D patient had a thickened calvarium, and the brain showed vacuolization of the neuropil in the cerebrum, cerebellum and brainstem, and patchy Purkinje cell loss. Axonal neuropathy and chronic denervation atrophy of the skeletal muscles were observed in the XP-A patient, but not in the XP-D patient.

Conclusions

These clinical manifestations and autopsy findings indicate advanced involvement of the central and peripheral nervous system. Despite similar defects in DNA repair, different clinicopathological phenotypes are seen in the four cases, and therefore distinct patterns of neurodegeneration characterize XP-D, XP-A and XP-C patients.

Abstract 2736: Genetic deletion of the prkar1a in the endocrine pancreas promotes neuroendocrine carcinogenesis

Background: Carney complex (CNC) is a rare disease inherited as an autosomal dominant trait, associated with various tumors, and caused most frequently by inactivation of the PRKAR1A gene. Recently a possible association of pancreatic neoplasms with CNC was reported in 9 out of 354 patients (2.5%), suggesting the potential role of PRKAR1A as a tumor suppressor gene in the pancreas.

Methods: Prkar1afl/fl and pdx-1-CRE mice were previously reported (Kirschner et al, 2005; Lammert et al, 2001) and were kept in a mixed genetic background (C57Bl/6 x FVB). Pdx1 is a transcription factor expressed in beta-insulin producing cells and in some a-glucagon producing cells of the mouse adult pancreatic islet. Both prkar1a alleles were conditionally deleted during development by generating pdx1-Cre; prkar1af/f mice (Δ–prkar1a). Mice were phenotyped at the age of 2, 4 and 6 months and tissues were collected for histological and molecular analysis.

Results: Mice developed endocrine or mixed endocrine/acinar cell carcinomas with 100% penetration by the age of 4-5 months. Malignant behavior of the tumors was defined by stromal invasion and regional lymph node metastasis. Histologically most tumors exhibited an organoid pattern as seen in the islet-cell tumors. Some tumors exhibited in addition foci suggestive of acinar cell differentiation. The primary neuroendocrine nature of the tumor cells was confirmed by immunohistochemical (IHC) staining for chromogranin and by electron microscopy, which revealed the characteristic neuroendocrine granules. Focal acinar differentiation was further supported by the finding of scattered chymotrypsin-positive cells by immunofluorescence (IF). Although the Δ-prkar1a mice developed hypoglycemia after overnight fasting, insulin and glucagon levels in the plasma didn't differ. The negative IHC staining for the most common produced peptides (insulin, c-peptide, glucagon, gastrin, somatostatin) suggested that these tumors are non-functional. The recombination that was confirmed by the detection of the mutated allele for the prkar1a in the tumor DNA, but neither in the germline of the KO animals nor in the islets DNA of the WT mice, resulted in increased PKA activity and lack of protein expression in the tumor compared to the normal pancreatic tissue. The latter finding is suggestive of the oncogenic effect of PRKAR1A inactivation. IF staining showed that the tumor cells were composed of a pdx1+/insulin- cell-population. We hypothesized that the recently identified multipotent pdx1+/insulin- cell in the adult pancreas, gives rise to endocrine, or mixed endocrine/acinar pancreatic malignancies upon PKA manipulation.

Conclusions: Loss of prkar1a function predisposes the endocrine pancreas to invasive cancers. This supports the role of prkar1a as a tumor suppressor gene in the pancreas and provides valuable tools to evaluate novel therapeutics in endocrine pancreas malignancies.

Citation Format: Emmanouil Saloustros, Maria Tsokos, Paraskevi Salpea, Matthew Starost, Sisi Liu, Li Guang, Maria Nesterova, Eva Szarek, Mehboob A. Hussain, Constantine A. Stratakis. Genetic deletion of the prkar1a in the endocrine pancreas promotes neuroendocrine carcinogenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2736. doi:10.1158/1538-7445.AM2013-2736

Abstract 3551: CD44 expression in Ewing sarcoma is associated with reduced chemosensitivity in vitro

CD44 is the primary hyaluronate (HA) receptor in a variety of cell types and has been implicated in several processes, such as cell-to-cell and cell-to-extracellular matrix interactions, cell migration and invasion, as well as metastasis and drug resistance. Even though CD44 expression has been studied in various types of cancer, such as prostate and lung cancer, little is known about its role in Ewing sarcoma, the second most common malignancy of bone and soft tissue in children and adolescents. We assessed the expression of CD44 in 25 cases of Ewing sarcoma by immunohistochemistry and found that CD44 is expressed in 40% of them. Furthermore, we noticed that in 4 out of 10 patients CD44 expression increased in one or more subsequent recurrent or metastatic biopsy samples. Therefore, we hypothesized that CD44+ cells in Ewing sarcoma represent cell clones, which are resistant to treatment and lead to tumor relapses. In order to study the role of CD44 in Ewing sarcoma, we cultured tumor cells for 24 to 72 hours in anchorage-independent sphere forming culture conditions, (low attachment plates), which are known to induce CD44 expression and compared them to adherent cells. CD44 mRNA and protein expression was induced in the anchorage-independent group as early as 24h in all 7 Ewing sarcoma cell lines. We then measured mRNA levels of ABCB5 and ABCC1, members of the superfamily of ATP-binding cassette (ABC) transporters related to drug resistance by real time PCR and found them increased. These data were corroborated by our finding of significantly increased efflux of the fluorescent DNA binding dye, Hoechst 33342, in the anchorage-independent group, indicating that the cells that overexpress CD44 are more effective in effluxing the chemotherapeutic drugs, thus becoming more resistant to chemotherapy. Finally, changes in the expression of efflux proteins were associated with increased resistance to doxorubicin-induced apoptotic cell death documented by increased expression of annexin V. In summary, our data indicate that CD44 is involved in drug resistance in Ewing sarcoma and may be clinically useful in making therapeutic decisions.

Citation Format: Nikolina Dioufa, Guang Li, Maria Tsokos. CD44 expression in Ewing sarcoma is associated with reduced chemosensitivity in vitro. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3551. doi:10.1158/1538-7445.AM2013-3551

Abstract 2963: Succinate dehydrogenase mutation underlies global epigenomic divergence in gastrointestinal stromal tumor

Although driver mutations in signal transduction kinases such as KIT are found in the majority of gastrointestinal stromal tumors (GIST), a subset of GISTs lack these mutations and instead exhibit loss-of-function defects in the mitochondrial succinate dehydrogenase (SDH) complex, a component of the Krebs cycle. To examine the effects of this metabolic defect on the epigenome, we used Illumina GoldenGate and 450K Infinium microarray technology to profile DNA methylation in GIST samples and uncovered markedly divergent global DNA methylation between SDH-null GIST (N=24) versus KIT or related tyrosine kinase pathway mutated GIST (N=39). When compared to reference normal tissues including intestinal smooth muscle (N=10) and neuronal tissue (N=13), SDH-deficient GIST was found to have an order of magnitude greater global hypermethylation than the kinase-pathway mutant group (84.9K vs. 8.4K targets, respectively). In a histologically distinct SDH-deficient tumor system, methylation divergence was further found among SDH-mutant paraganglioma/pheochromocytoma (N=29) using an adrenal tissue (N=15) reference baseline. These data expose an essential role for succinate metabolism in the maintenance of DNA methylation programming and tumor suppression. Because defects in other Krebs cycle enzymes are also oncogenic, we further sought to determine whether this phenomenon was confined to SDH-deficient tumors. Analysis of SDH-mutant GIST and isocitrate dehydrogenase (IDH)-mutant gliomas revealed comparable quantities of global hypo- and hypermethylated targets. We propose that this phenomenon may result from a failure of maintenance demethylation, secondary to inactivation of the TET2 5-methylcytosine dioxgenase system by the inhibitory metabolites succinate (in SDH deficient tumors) or 2-hydroxyglutarate (in IDH mutant tumors). While the biological ramifications of this distortion of the epigenome remain to be elucidated, this study clearly implicates the Krebs cycle as mitochondrial custodian of the methylome in diverse cancers.

Citation Format: Paul S. Meltzer, J. Keith Killian, Su Young Kim, Markku Miettinen, Carly Smith, Maria Tsokos, Martha Quezado, William I. Smith, Mona S. Jahromi, Robert L. Walker, Jerzy Lasota, Brandy Klotzle, Zengfeng Wang, Laura Jones, Yuelin Zhu, Yonghong Wang, Joshua J. Waterfall, Marina Bibikova, Maureen J. O'Sullivan, Constantine A. Stratakis, Joshua D. Schiffman, Jian-Bing Fan, Lee Helman. Succinate dehydrogenase mutation underlies global epigenomic divergence in gastrointestinal stromal tumor. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2963. doi:10.1158/1538-7445.AM2013-2963

Succinate dehydrogenase mutation underlies global epigenomic divergence in gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GIST) harbor driver mutations of signal transduction kinases such as KIT, or, alternatively, manifest loss-of-function defects in the mitochondrial succinate dehydrogenase (SDH) complex, a component of the Krebs cycle and electron transport chain. We have uncovered a striking divergence between the DNA methylation profiles of SDH-deficient GIST (n = 24) versus KIT tyrosine kinase pathway-mutated GIST (n = 39). Infinium 450K methylation array analysis of formalin-fixed paraffin-embedded tissues disclosed an order of magnitude greater genomic hypermethylation relative to SDH-deficient GIST versus the KIT-mutant group (84.9 K vs. 8.4 K targets). Epigenomic divergence was further found among SDH-mutant paraganglioma/pheochromocytoma (n = 29), a developmentally distinct SDH-deficient tumor system. Comparison of SDH-mutant GIST with isocitrate dehydrogenase-mutant glioma, another Krebs cycle-defective tumor type, revealed comparable measures of global hypo- and hypermethylation. These data expose a vital connection between succinate metabolism and genomic DNA methylation during tumorigenesis, and generally implicate the mitochondrial Krebs cycle in nuclear epigenomic maintenance.

Chronic myopathy due to immunoglobulin light chain amyloidosis

Amyloid myopathy associated with a plasma cell dyscrasia is a rare cause of muscle hypertrophy. It can be a challenging diagnosis, since pathological findings are often elusive. In addition, the mechanism by which immunoglobulin light-chain deposition stimulates muscle overgrowth remains poorly understood. We present a 53-year old female with a 10-year history of progressive generalized muscle overgrowth. Congo-red staining and immunohistochemistry revealed perivascular lambda light chain amyloid deposits, apparent only in a second muscle biopsy. The numbers of central nuclei and satellite cells were increased, suggesting enhanced muscle progenitor cell formation. Despite the chronicity of the light chain disease, the patient showed complete resolution of hematologic findings and significant improvement of her muscle symptoms following autologous bone marrow transplantation. This case highlights the importance of early diagnosis and therapy for this treatable cause of a chronic myopathy with muscle hypertrophy.

Pegylated siRNA-loaded calcium phosphate nanoparticle-driven amplification of cancer cell internalization in vivo

The cell membrane is a critical barrier to effective delivery for many therapeutics, including those which are nanoparticle-based. Improving nanoparticle transport across the cell membrane remains a fundamental challenge. Cancer cells preferentially internalized pegylated calcium phosphate nanoparticles over normal epithelial cells. Furthermore, non-cytotoxic levels of doxorubicin markedly amplified this difference by increasing free unbound caveolin-1 and resulted in enhanced caveolin-mediated nanoparticle endocytosis in cancer cells. Engineered pegylated siRNA-loaded triple-shell calcium phosphate nanoconstructs incorporating ultra-low levels of doxorubicin recapitulated these effects and delivered increased numbers of siRNA into cancer cells with target-specific results. Systemic administration of nanoparticles in vivo demonstrated highly preferential entry into tumors, little bystander organ biodistribution, and significant tumor growth arrest. In conclusion, siRNA-loaded calcium phosphate nanoparticles incorporating non-cytotoxic amounts of doxorubicin markedly enhances nanoparticle internalization and results in increased payload delivery with concomitant on-target effects.

18-fluorodeoxyglucose-positron emission tomography (FDG-PET) evaluation of nodular lesions in patients with Neurofibromatosis type 1 and plexiform neurofibromas (PN) or malignant peripheral nerve sheath tumors (MPNST)

BACKGROUND

Individuals with Neurofibromatosis type 1 (NF1) are at risk for developing malignant peripheral nerve sheath tumors (MPNST), which frequently arise in preexisting plexiform neurofibromas (PN). Magnetic resonance imaging (MRI) with volumetric analysis and 18-fluorodeoxyglucose-positron emission tomography (FDG-PET) were utilized to monitor symptomatic nodular lesions.

PROCEDURE

Patients with NF1 and PN on a NCI natural history trial were monitored for total body tumor volume (TTV) using volumetric MRI. FDG-PET was performed in individuals with a nodular well-demarcated lesion ≥3 cm if they were growing, painful, or there was a prior history of MPNST (target lesions). Asymptomatic nodular lesions were evaluated as non-target lesions.

RESULTS

Fifteen patients (8m, 7f) median age of 18.3 years (range, 10-45 years) had a single target and non-target (n = 46) nodular lesions identified on MRI. Target lesions arose within (n = 8) or outside (n = 3) a PN, and all but 1 had increased FDG uptake. FDG uptake was increased in non-target lesions but to a lesser degree. FDG uptake in the surrounding PN was low, similar to background activity. Pathologic evaluation performed in 11 patients demonstrated neurofibroma (n = 6), atypical neurofibroma (n = 2) and malignancy (n = 3).

CONCLUSIONS

Nodular target lesions identified on MRI in individuals with NF1 and PN demonstrate increased FDG uptake similar to MPNST, but may be benign on biopsy. Nodular target lesions may be at greater risk for malignant transformation, but their biologic and clinical behavior has not been well studied. Careful longitudinal evaluation will be required to better understand the malignant potential of these lesions.

Changes to the cell, tissue and architecture levels in cranial suture synostosis reveal a problem of timing in bone development

Premature fusion of cranial sutures is a common problem with an incidence of 3-5 per 10,000 live births. Despite progress in understanding molecular/genetic factors affecting suture function, the complex process of premature fusion is still poorly understood. In the present study, corresponding excised segments of nine patent and nine prematurely fused sagittal sutures from infants (age range 3-7 months) with a special emphasis on their hierarchical structural configuration were compared. Cell, tissue and architecture characteristics were analysed by transmitted and polarised light microscopy, 2D-histomorphometry, backscattered electron microscopy and energy-dispersive-x-ray analyses. Apart from wider sutural gaps, patent sutures showed histologically increased new bone formation compared to reduced new bone formation and osseous edges with a more mature structure in the fused portions of the sutures. This pattern was accompanied by a lower osteocyte lacunar density and a higher number of evenly mineralised osteons, reflecting pronounced lamellar bone characteristics along the prematurely fused sutures. In contrast, increases in osteocyte lacunar number and size accompanied by mineralisation heterogeneity and randomly oriented collagen fibres predominantly signified woven bone characteristics in patent, still growing suture segments. The already established woven-to-lamellar bone transition provides evidence of advanced bone development in synostotic sutures. Since structural and compositional features of prematurely fused sutures did not show signs of pathological/defective ossification processes, this supports the theory of a normal ossification process in suture synostosis - just locally commencing too early. These histomorphological findings may provide the basis for a better understanding of the pathomechanism of craniosynostosis, and for future strategies to predict suture fusion and to determine surgical intervention.

Endogenous thrombospondin-1 regulates leukocyte recruitment and activation and accelerates death from systemic candidiasis

Disseminated Candida albicans infection results in high morbidity and mortality despite treatment with existing antifungal drugs. Recent studies suggest that modulating the host immune response can improve survival, but specific host targets for accomplishing this goal remain to be identified. The extracellular matrix protein thrombospondin-1 is released at sites of tissue injury and modulates several immune functions, but its role in C. albicans pathogenesis has not been investigated. Here, we show that mice lacking thrombospondin-1 have an advantage in surviving disseminated candidiasis and more efficiently clear the initial colonization from kidneys despite exhibiting fewer infiltrating leukocytes. By examining local and systemic cytokine responses to C. albicans and other standard inflammatory stimuli, we identify a crucial function of phagocytes in this enhanced resistance. Subcutaneous air pouch and systemic candidiasis models demonstrated that endogenous thrombospondin-1 enhances the early innate immune response against C. albicans and promotes activation of inflammatory macrophages (inducible nitric oxide synthase⁺, IL-6^high, TNF-α^high, IL-10^low), release of the chemokines MIP-2, JE, MIP-1α, and RANTES, and CXCR2-driven polymorphonuclear leukocytes recruitment. However, thrombospondin-1 inhibited the phagocytic capacity of inflammatory leukocytes in vivo and in vitro, resulting in increased fungal burden in the kidney and increased mortality in wild type mice. Thus, thrombospondin-1 enhances the pathogenesis of disseminated candidiasis by creating an imbalance in the host immune response that ultimately leads to reduced phagocytic function, impaired fungal clearance, and increased mortality. Conversely, inhibitors of thrombospondin-1 may be useful drugs to improve patient recovery from disseminated candidiasis.

CD47 deficiency confers cell and tissue radioprotection by activation of autophagy

Accidental or therapeutic exposure to ionizing radiation has severe physiological consequences and can result in cell death. We previously demonstrated that deficiency or blockade of the ubiquitously expressed receptor CD47 results in remarkable cell and tissue protection against ischemic and radiation stress. Antagonists of CD47 or its ligand THBS1/thrombospondin 1 enhance cell survival and preserve their proliferative capacity. However the signaling pathways that mediate this cell-autonomous radioprotection are unclear. We now report a marked increase in autophagy in irradiated T-cells and endothelial cells lacking CD47. Irradiated T cells lacking CD47 exhibit significant increases in formation of autophagosomes comprising double-membrane vesicles visualized by electron microscopy and numbers of MAP1LC3A/B(+) puncta. Moreover, we observed significant increases in BECN1, ATG5, ATG7 and a reduction in SQSTM1/p62 expression relative to irradiated wild-type T cells. We observed similar increases in autophagy gene expression in mice resulting from blockade of CD47 in combination with total body radiation. Pharmacological or siRNA-mediated inhibition of autophagy selectively sensitized CD47-deficient cells to radiation, indicating that enhanced autophagy is necessary for the prosurvival response to CD47 blockade. Moreover, re-expression of CD47 in CD47-deficient T cells sensitized these cells to death by ionizing radiation and reversed the increase in autophagic flux associated with survival. This study indicates that CD47 deficiency confers cell survival through the activation of autophagic flux and identifies CD47 blockade as a pharmacological route to modulate autophagy for protecting tissue from radiation injury.

Disseminated microsporidiosis in an immunosuppressed patient

We report a case of disseminated microsporidiosis in a patient with multiple myeloma who had received an allogeneic stem cell transplant requiring substantial immunosuppression. The causative organism was identified as Tubulinosema acridophagus, confirming this genus of microsporidia as a novel human pathogen.

Phase I trial and pharmacokinetic study of lexatumumab in pediatric patients with solid tumors

PURPOSE

Lexatumumab is an agonistic, fully human monoclonal antibody against tumor necrosis factor-related apoptosis-inducing ligand receptor 2 with preclinical evidence of activity in pediatric solid tumors.

PATIENTS AND METHODS

This phase I dose-escalation study examined the safety, tolerability, pharmacokinetics, and immunogenicity of lexatumumab at doses up to, but not exceeding, the adult maximum-tolerated dose (3, 5, 8, and 10 mg/kg), administered once every 2 weeks to patients age≤21 years with recurrent or progressive solid tumors.

RESULTS

Twenty-four patients received a total of 56 cycles of lexatumumab over all four planned dose levels. One patient had grade 2 pericarditis consistent with radiation recall, and one patient developed grade 3 pneumonia with hypoxia during the second cycle. Five patients experienced stable disease for three to 24 cycles. No patients experienced complete or partial response, but several showed evidence of antitumor activity, including one patient with recurrent progressive osteosarcoma who experienced resolution of clinical symptoms and positron emission tomography activity, ongoing more than 1 year off therapy. One patient with hepatoblastoma showed a dramatic biomarker response.

CONCLUSION

Pediatric patients tolerate 10 mg/kg of lexatumumab administered once every 14 days, the maximum-tolerated dose identified in adults. The drug seems to mediate some clinical activity in pediatric solid tumors and may work with radiation to enhance antitumor effects.

Copy number aberrations of BCL2 and CDKN2A/B identified by array-CGH in thymic epithelial tumors

The molecular pathology of thymic epithelial tumors (TETs) is largely unknown. Using array comparative genomic hybridization (CGH), we evaluated 59 TETs and identified recurrent patterns of copy number (CN) aberrations in different histotypes. GISTIC algorithm revealed the presence of 126 significant peaks of CN aberration, which included 13 cancer-related genes. Among these peaks, CN gain of BCL2 and CN loss of CDKN2A/B were the only genes in the respective regions of CN aberration and were associated with poor outcome. TET cell lines were sensitive to siRNA knockdown of the anti-apoptotic molecules BCL2 and MCL1. Gx15-070, a pan-BCL2 inhibitor, induced autophagy-dependent necroptosis in TET cells via a mechanism involving mTOR pathways, and inhibited TET xenograft growth. ABT263, an inhibitor of BCL2/BCL-XL/BCL-W, reduced proliferation in TET cells when administered in combination with sorafenib, a tyrosine kinase inhibitor able to downregulate MCL1. Immunohistochemistry on 132 TETs demonstrated that CN loss of CDKN2A correlated with lack of expression of its related protein p16^INK4 and identified tumors with poor prognosis. The molecular markers BCL2 and CDKN2A may be of potential value in diagnosis and prognosis of TETs. Our study provides the first preclinical evidence that deregulated anti-apoptotic BCL2 family proteins may represent suitable targets for TET treatment.

Ceramide mediates nanovesicle shedding and cell death in response to phosphatidylinositol ether lipid analogs and perifosine

Anticancer phospholipids that inhibit Akt such as the alkylphospholipid perifosine (Per) and phosphatidylinositol ether lipid analogs (PIAs) promote cellular detachment and apoptosis and have a similar cytotoxicity profile against cancer cell lines in the NCI60 panel. While investigating the mechanism of Akt inhibition, we found that short-term incubation with these compounds induced rapid shedding of cellular nanovesicles containing EGFR, IGFR and p-Akt that occurred in vitro and in vivo, while prolonged incubation led to cell detachment and death that depended on sphingomyelinase-mediated generation of ceramide. Pretreatment with sphingomyelinase inhibitors blocked ceramide generation, decreases in phospho-Akt, nanovesicle release and cell detachment in response to alkylphospholipids and PIAs in non-small cell lung cancer cell lines. Similarly, exogenous ceramide also decreased active Akt and induced nanovesicle release. Knockdown of neutral sphingomyelinase decreased, whereas overexpression of neutral or acid sphingomyelinase increased cell detachment and death in response to the compounds. When transferred in vitro, PIA or Per-induced nanovesicles increased ceramide levels and death in recipient cells. These results indicate ceramide generation underlies the Akt inhibition and cytotoxicity of this group of agents, and suggests nanovesicle shedding and uptake might potentially propagate their cytotoxicity in vivo.

High-throughput molecular and histopathologic profiling of tumor tissue in a novel transplantable model of murine neuroblastoma: new tools for pediatric drug discovery

Using two MYCN transgenic mouse strains, we established 10 transplantable neuroblastoma cell lines via serial orthotopic passage in the adrenal gland. Tissue arrays demonstrate that by histochemistry, vascularity, immunohistochemical staining for neuroblastoma markers, catecholamine analysis, and concurrent cDNA microarray analysis, there is a close correspondence between the transplantable lines and the spontaneous tumors. Several genes closely associated with the pathobiology and immune evasion of neuroblastoma, novel targets that warrant evaluation, and decreased expression of tumor suppressor genes are demonstrated. These studies describe a unique and generalizable approach to expand the utility of transgenic models of spontaneous tumor, providing new tools for preclinical investigation.

Interstitial lung disease and pulmonary fibrosis in Hermansky-Pudlak syndrome type 2, an adaptor protein-3 complex disease

Pulmonary fibrosis develops in Hermansky-Pudlak syndrome (HPS) types 1 and 4. Limited information is available about lung disease in HPS type 2 (HPS-2), which is characterized by abnormal function of the adaptor protein-3 (AP-3) complex. To define lung disease in HPS-2, one child and two adults with HPS-2 were evaluated at the National Institutes of Health on at least two visits, and another child was evaluated at the University of Texas Health Science Center San Antonio. All four subjects with HPS-2 had findings of interstitial lung disease (ILD) on a high-resolution computed tomography scan of the chest. The predominant feature was ground glass opacification. Subject 1, a 14-year-old male, and subject 4, a 4-year-old male, had severe ILD, pulmonary fibrosis, secondary pulmonary hypertension and recurrent lung infections. Lung biopsy performed at 20 months of age in subject 1 revealed interstitial fibrosis and prominent type II pneumocyte hyperplasia without lamellar body enlargement. Subject 2, a 27-year-old male smoker, had mild ILD. Subject 3, a 22-year-old male nonsmoker and brother of subject 2, had minimal ILD. Severe impairment of gas exchange was found in subjects 1 and 4 and not in subjects 2 or 3. Plasma concentrations of transforming growth factor-β1 and interleukin-17A correlated with severity of HPS-2 ILD. These data show that children and young adults with HPS-2 and functional defects of the AP-3 complex are at risk for ILD and pulmonary fibrosis.

Ewing sarcoma/peripheral primitive neuroectodermal tumor and related tumors

Ewing sarcoma/peripheral primitive neuroectodermal tumor (EWS/pPNET) and other tumors with EWS gene rearrangements encompass a malignant and intermediate neoplasm with a broad anatomic distribution and a wide age range but a predilection for soft tissue in children, adolescents, and young adults. The overlapping histologic, immunohistochemical and cytogenetic and molecular genetic features create diagnostic challenges despite significant clinical and prognostic differences. Ewing sarcoma is the 3rd most common sarcoma in children and adolescents, and desmoplastic small round cell tumor is a rare neoplasm that occurs more often in older children, adolescents, and young adults. Pathologic examination is complemented by immunohistochemistry, cytogenetics, and molecular genetics. This article reviews the clinicopathologic features of EWS/pPNET and desmoplastic small round cell tumor in the spectrum of tumors with EWS gene rearrangements. Other tumors with different histopathologic features and an EWS gene rearrangement are discussed elsewhere in this volume.

Murine rhabdomyosarcoma is immunogenic and responsive to T-cell-based immunotherapy

BACKGROUND

Immunotherapies targeting cellular immunity are currently approved for treatment of melanoma, renal cell carcinoma, and prostate cancer. Studies on the immunogenicity and immune responsiveness of pediatric tumors are limited, therefore, it remains unclear to what extent T-cell-based immunotherapy holds promise for pediatric solid tumors.

PROCEDURE

A new rhabdomyosarcoma cell line (M3-9-M) was derived from an embryonal rhabdomyosarcoma (ERMS) occurring in a C57BL/6 mouse transgenic for hepatocyte growth factor and heterozygous for mutated p53. Primary tumors and metastases derived from M3-9-M were studied for similarities to human ERMS, and for immunogenicity and immune responsiveness.

RESULTS

Primary and metastatic tumors develop after orthotopic injection of M3-9-M into immunocompetent C57BL/6 mice, which mirror human ERMS with regard to histology, gene expression, and metastatic behavior. Whole cell vaccination using irradiated M3-9-M cells or M3-9-M-pulsed dendritic cells (DC)-induced tumor-specific T-cell responses that prevent tumor growth following low-dose tumor injection, and slow tumor growth following higher doses. Administration of anti-CD25 moAbs to deplete CD4(+)CD25(+)FOXP3(+) regulatory T cells prior to tumor vaccination enhanced the potency of the ERMS tumor vaccine. Adoptive immunotherapy with M3-9-M primed T cells plus DC-based vaccination resulted in complete eradication of day 10 M3-9-M derived tumors.

CONCLUSIONS

M3-9-M derived murine ERMS is immunogenic and immunoresponsive; regulatory T cells contribute to immune evasion by murine rhabdomyosarcoma. Adoptive immunotherapy with DC vaccination can eradicate low tumor burdens. Future work will seek to identify the tumor-associated antigens that mediate protective and therapeutic immunity in this model.

Abstract 960: Ceramide-dependent release of nanovesicles is a class effect oflipid-based Akt inhibitors

Akt regulates many cellular processes and Akt inhibitors are being developed as cancer therapeutics. The mechanism of action of lipid-based Akt inhibitors (LBAIs) such as perifosine and phosphatidylinositol ether lipid analogues (PIAs) is incompletely understood. Here, we show that LBAIs quickly deplete cells of proteins such as EGFR, IGFR and p-Akt that can be recovered in tetraspanin-enriched 100,000 xg pellets from conditioned media. Electron micrographs of these pellets exhibited heterogenous vesicular structures whose diameter was less than 1 µM. In vitro, LBAI treatment increased vesicle shedding as revealed by live cell microscopy. In vivo, LBAIs increased plasma levels of nanovesicles derived from tumor xenografts. Several lines of evidence show that release of nanovesicles by LBAI depends upon ceramide generation. LBAIs increased levels of cellular ceramide, and addition of exogenous ceramide stimulated nanovesicle release. GW4869, an inhibitor of sphingomyelinase, an enzyme that generates ceramide by cleavage of sphingomyelin, blocked release of nanovesicles induced by LBAI. When transferred in vitro, purified nanovesicles increased ceramide levels and inhibited proliferation of naïve recipient cells, suggesting these contain residual LBAIs. Pre-treatment with GW4869 blocked ceramide induction in recipient cells and yielded greater retention of the donor nanovesicles. These studies identify ceramide-dependent release of cellular nanovesicles as a class effect of LBAI and a novel means to shed EGFR, IGF-IR and p-Akt from tumors that could perpetuate the cytotoxicity of LBAIs. We believe this is the first report of secondary pharmacologic effects via cell-mediated drug transfer in nanovesicles.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 960. doi:10.1158/1538-7445.AM2011-960