Single-cell transcriptomics and epigenomics unravel the role of monocytes in neuroblastoma bone marrow metastasis.

Metastasis is the major cause of cancer-related deaths. Neuroblastoma (NB), a childhood tumor has been molecularly defined at the primary cancer site, however, the bone marrow (BM) as the metastatic niche of NB is poorly characterized. Here we perform single-cell transcriptomic and epigenomic profiling of BM aspirates from 11 subjects spanning three major NB subtypes and compare these to five age-matched and metastasis-free BM, followed by in-depth single cell analyses of tissue diversity and cell-cell interactions, as well as functional validation. We show that cellular plasticity of NB tumor cells is conserved upon metastasis and tumor cell type composition is NB subtype-dependent. NB cells signal to the BM microenvironment, rewiring via macrophage mgration inhibitory factor and midkine signaling specifically monocytes, which exhibit M1 and M2 features, are marked by activation of pro- and anti-inflammatory programs, and express tumor-promoting factors, reminiscent of tumor-associated macrophages. The interactions and pathways characterized in our study provide the basis for therapeutic approaches that target tumor-to-microenvironment interactions.

Nestin expression in osteocytes following myeloablation and during bone marrow metastasis.

Nestin is an intermediate filament protein, which was originally detected in neuroepithelial stem cells. Besides its use as a phenotypic marker of mesenchymal stem cells in the hematopoeitic stem cell niche, the functional interpretation of nestin+ cells remains elusive. We investigated the cellular expression of nestin in bone marrow trephine biopsies of MPN patients, following myeloablation at a stage of hypocellularity during early regeneration. Here, nestin is highly expressed in mature osteocytes, arteriolar endothelial and perivascular cells and small capillaries within the bone marrow space, but not in sinusoid lining cells. This is in stark contrast to nestin expression pattern in myeloproliferative neoplasms that show hypercellularity due to oncogenic driver mutations. Here, nestin is expressed exclusively in endothelial cells of arterioles, but not in osteocytes or small capillaries. Thus, the pattern of nestin expression following myeloablation inversely correlates with cellularity in the bone marrow. This nestin expression pattern is mimicking early postnatal transcriptional programming during bone marrow development. We show that nestin expression in osteocytes occurs across different species following transplant and also in bone marrow metastasis.

Toll-like receptor gene polymorphisms in patients with myeloproliferative neoplasms.

Toll-like receptors (TLRs) are a family of transmembrane receptors whose signaling control cellular processes of cell proliferation, survival, apoptosis, angiogenesis, remodeling, and repair of tissues. Polymorphisms in TLR genes can change the balance between pro and anti-inflammatory cytokines, modulating the risk of infection, chronic inflammation, and cancer. Although many studies have demonstrated the direct involvement of TLR signaling in the benefit of tumor cells in certain cancers, little is known about the influence of these gene polymorphisms on myeloproliferative neoplasms (MPNs). In this context, the objective of the study was to investigate a possible association between the TLR polymorphisms and the development of MPNs. 167 patients diagnosed with MPN and 222 healthy controls from the same region were evaluated. Genomic DNA was extracted and the TLR2 (rs5743708), TLR4 (rs4986790, rs4986791), TLR9 (rs5743836, rs187084) and JAK2V617F polymorphisms were genotyped by PCR-RFLP. The statistical analysis was performed by OpenEpi and SNPstat software. The JAK2V617F mutation was found in 68.32% of patients. TLR9-1486C/T CT genotype was less frequent in patients with polycythemia vera (PV) (OR 0.39, 95% CI 0.20-0.78, P = 0.025). When haplotype frequencies were analyzed, -1237T/-1486C (TLR9) was also less frequent in men (OR 0.58, 95% CI 0.36-0.94) and JAK negative men patients (OR 0.43, 95% CI 0.21-0.88). We can infer that the TLR9-1486 CT genotype could be associated with protection for PV and the TLR9-1237T/-1486C haplotype, protection for men, as well as for JAK negative men patients with MPN. There were no associations between TLR2 and TLR4 gene polymorphisms and MPN.

GAS7 Deficiency Promotes Metastasis in MYCN-Driven Neuroblastoma.

One of the greatest barriers to curative treatment of neuroblastoma is its frequent metastatic outgrowth prior to diagnosis, especially in cases driven by amplification of the MYCN oncogene. However, only a limited number of regulatory proteins that contribute to this complex MYCN-mediated process have been elucidated. Here we show that the growth arrest-specific 7 (GAS7) gene, located at chromosome band 17p13.1, is preferentially deleted in high-risk MYCN-driven neuroblastoma. GAS7 expression was also suppressed in MYCN-amplified neuroblastoma lacking 17p deletion. GAS7 deficiency led to accelerated metastasis in both zebrafish and mammalian models of neuroblastoma with overexpression or amplification of MYCN. Analysis of expression profiles and the ultrastructure of zebrafish neuroblastoma tumors with MYCN overexpression identified that GAS7 deficiency led to (i) downregulation of genes involved in cell-cell interaction, (ii) loss of contact among tumor cells as critical determinants of accelerated metastasis, and (iii) increased levels of MYCN protein. These results provide the first genetic evidence that GAS7 depletion is a critical early step in the cascade of events culminating in neuroblastoma metastasis in the context of MYCN overexpression. SIGNIFICANCE: Heterozygous deletion or MYCN-mediated repression of GAS7 in neuroblastoma releases an important brake on tumor cell dispersion and migration to distant sites, providing a novel mechanism underlying tumor metastasis in MYCN-driven neuroblastoma.See related commentary by Menard, p. 2815.

A nomogram of clinical and biologic factors to predict survival in children newly diagnosed with high-risk neuroblastoma: An International Neuroblastoma Risk Group project.

BACKGROUND: Long-term outcome remains poor for children with high-risk neuroblastoma (five-year overall survival [OS] ∼50%). Our objectives were to (a) identify prognostic biomarkers and apply them in a nomogram to identify the subgroup of ultra-high-risk patients at highest risk of disease progression/death, for whom novel frontline therapy is urgently needed; and (b) validate the nomogram in an independent cohort. METHODS: A total of 1820 high-risk patients (≥18 months old with metastatic neuroblastoma), diagnosed 1998-2015, from the International Neuroblastoma Risk Groups (INRG) Data Commons were analyzed in a retrospective cohort study. Using multivariable Cox regression of OS from diagnosis, a nomogram was created from prognostic biomarkers to predict three-year OS. External validation was performed using the SIOPEN HR-NBL1 trial cohort (n = 521), evidenced by receiver operating characteristic curves. RESULTS: The nomogram, including MYCN status (P < 0.0001), lactate dehydrogenase (LDH) (P = 0.0007), and presence of bone marrow metastases (P = 0.004), had robust performance and was validated. Applying the nomogram at diagnosis (a) gives prognosis of an individual patient and (b) identifies patients predicted to have poor outcome (three-year OS was 30% ± 5% for patients with a nomogram score of > 82 points; 58% ± 1% for those ≤82 points). Median follow-up time was 5.5 years (range, 0-14.1). CONCLUSIONS: In high-risk neuroblastoma, a novel, publicly available nomogram using prognostic biomarkers (MYCN status, LDH, presence of bone marrow metastases; https://neuroblastoma.shinyapps.io/High-Risk-Neuroblastoma-Nomogram/) has the flexibility to apply a clinically suitable and context-specific cutoff to identify patients at highest risk of death. This will facilitate testing urgently needed new frontline treatment options to improve outcome for these children.

SNHG12 inhibits oxygen­glucose deprivation­induced neuronal apoptosis via the miR­181a­5p/NEGR1 axis.

Emerging evidence has indicated that long non­coding RNAs (lncRNAs) are closely associated with the pathogenesis of ischemic stroke. It has been reported that small nucleolar RNA host gene 12 (SNHG12) serves a critical role in ischemic stroke by acting as a competitive endogenous RNA (ceRNA). SNHG12 competes with various microRNAs (miRs) to regulate RNA transcription of specific targets. However, the effect of SNHG12 on oxygen­glucose deprivation (OGD)­induced neuronal apoptosis has rarely been reported. The present study demonstrated that SNHG12 expression was downregulated in OGD­injured SH­SY5Y cells. Furthermore, miR­181a­5p was reported as a target of SNHG12 and was negatively regulated by SNHG12. Moreover, NEGR1 was a target of miR­181a­5p, which functions as a negative regulator of NEGR1 in OGD­induced neuronal apoptosis. In summary, the results strongly confirmed the hypothesis that SNHG12 functions as a ceRNA for miR­181a­5p and regulates the expression of NEGR1 thus inhibiting OGD­induced apoptosis of SH­SY5Y cells. Neuronal apoptosis aggravates brain damage during ischemic stroke, indicating that the activation of SNHG12 and NEGR1 expression and inhibition of miR­181a­5p may be a novel strategy for the clinical treatment of ischemic stroke.

Combined use of multiparametric flow cytometry and cytomorphology to enhance detection of neuroblastoma metastatic cells in bone marrow.

INTRODUCTION: In the context of neuroblastoma (NB), the screening for bone marrow (BM) metastasis is a recurrent issue for hematology laboratory routine practice. Detection of low tumor burden using light microscopy is often difficult. In this regard, our objective was to evaluate the performance of multiparametric flow cytometry (FC) for detecting NB metastatic cells in BM. METHODS: We applied a new FC multiparametric panel allowing the analysis of the co-expression of 5 surface markers: GD2 (disialoganglioside 2), CD9, CD56, CD81, and CD90, on CD45-negative BM cell populations, and compared results with BM biopsy immunohistochemistry, which is the reference method. RESULTS: In spike-in tests, the multiparametric FC successfully detected NB cells mixed in peripheral blood mononuclear cells to a level of 0.01%. FC analysis was performed on 45 sets of BM aspirates sampled from 21 children, either at diagnosis or during follow-up. Combining multiparametric FC with light microscopy improved NB metastasis detection, with a higher sensitivity (76.9% vs 61.5%) and a higher specificity (94.4% vs 77.8%) as compared to light microscopy alone. At the time of diagnosis, multiparametric FC detected NB metastatic cells in all cases. CONCLUSION: These results illustrate the performance of multiparametric FC analysis to detect metastatic BM infiltration of NB. This is of particular interest in an emergency context, since when combined with light microscopy, it enhances the detection of metastatic invasion within a short timeframe, allowing an adapted and rapid clinical management.

The notch target gene HEYL modulates metastasis forming capacity of colorectal cancer patient-derived spheroid cells in vivo.

BACKGROUND: While colorectal cancer (CRC) patients with localized disease have a favorable prognosis, the five-year-survival rate in patients with distant spread is still below 15%. Hence, a detailed understanding of the mechanisms regulating metastasis formation is essential to develop therapeutic strategies targeting metastasized CRC. The notch pathway has been shown to be involved in the metastatic spread of various tumor entities; however, the impact of its target gene HEYL remains unclear so far. METHODS: In this study, we functionally assessed the association between high HEYL expression and metastasis formation in human CRC. Therefore, we lentivirally overexpressed HEYL in two human patient-derived CRC cultures differing in their spontaneous metastasizing capacity and analyzed metastasis formation as well as tumor cell dissemination into the bone marrow after xenotransplantation into NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. RESULTS: HEYL overexpression decreased tumor cell dissemination and the absolute numbers of formed metastases in a sub-renal capsular spontaneous metastasis formation model, addressing all steps of the metastatic cascade. In contrast, metastatic capacity was not decreased following intrasplenic xenotransplantation where the cells are placed directly into the blood circulation. CONCLUSION: These results suggest that HEYL negatively regulates metastasis formation in vivo presumably by inhibiting intravasation of metastasis-initiating cells.

Metabolic Effects of JAK1/2 Inhibition in Patients with Myeloproliferative Neoplasms.

Ruxolitinib is an FDA approved janus kinase (JAK)1/2 inhibitor used to treat myeloproliferative neoplasms (MPNs), including myelofibrosis and polycythemia vera. We aimed to determine the metabolic consequences of ruxolitinib treatment in patients with MPNs. We performed a retrospective single-center cohort study utilizing an electronic medical record based database of patients who began treatment with ruxolitinib for MPNs from January 2010 to March 2017. We also examined the effects of ruxolitinib on adipose tissue JAK/STAT signaling in a mouse model. 127 patients were identified, of which 69 had data available for weight, and at least one other parameter of interest before, and 72 weeks after starting ruxolitinib. Mean baseline weight was 73.9 ± 17.0 kg, and 78.54 ± 19.1 kg at 72 weeks (p < 0.001). 50% of patients gained >5% body weight. Baseline body mass index (BMI) was 25.8 ± 4.8 kg/m2, and 27.5 ± 5.5 kg/m2 at 72 weeks (p < 0.001). Patients treated with ruxolitinib had a higher systolic blood pressure, serum AST, and ALT at 72 weeks, compared with baseline (p = 0.03, p = 0.01, p = 0.04, respectively). In mice, ruxolitinib decreased basal and GH-stimulated STAT5 phosphorylation in adipose tissue. As pharmacological JAK1/2 inhibitors are being developed and used in clinical practice, it is important to understand their long-term metabolic consequences.

Auer rod-like inclusions in the cytoplasm of B-cell lymphoma cells with bone marrow infiltration.

Auer rod-like inclusions are rarely seen in B-cell neoplasms patients. Here, we present a case of B-cell lymphoma with Auer rod-like inclusions in lymphoma cells. By light and transmission electron microscopy, these structures closely resembled Auer rods which were found in acute myeloid leukemia. The Auer rod-like inclusions were negative for cytochemical staining of MPO, α-naphthyl acetate esterase, and periodic acid-Schiff. Immunostaining and flow cytometric analysis confirmed monoclonal Kappa-positive malignant lymphocytes. Interestingly, the Auer rod-like inclusions exhibited diverse ultrastructural features, which ranged from fusiform, to needle-shape, to round, to crystalline cuboid, to long rod, to short rod and others; some were membrane structures, some membrane-free dense structures, and some lamellar structures. The patient was diagnosed with B-cell lymphoma with bone marrow infiltration.

Bone marrow findings in metastatic melanoma, including role of BRAF immunohistochemistry.

INTRODUCTION: We describe peripheral blood smear, bone marrow morphology, histopathology, immunohistochemistry, including BRAF V600E, and molecular testing results of patients with metastatic melanoma to the bone marrow. METHODS: We performed a retrospective review for patients with metastatic melanoma to the bone marrow at our institution. Bone marrow morphology, histology, immunophenotyping, and cytogenetic/molecular genetic testing were reviewed, and BRAF V600E immunohistochemistry was performed. Results were compared to the literature. RESULTS: We identified four patients with metastatic melanoma to the bone marrow presenting with at least one cytopenia. Two of the four patients had leukoerythroblastosis, with three patients having atypical cells on bone marrow aspirate/touch preparation, and all patients had aggregates of atypical cells on biopsy. Immunohistochemistry for S100, Melan A, and HMB45 confirmed the diagnosis in all patients, and BRAF V600E immunohistochemistry was detected in two of four patients, which correlated with molecular testing findings. Review of the literature found 27 total patients, with normocytic anemia and leukoerythroblastosis as common peripheral blood smear findings. CONCLUSIONS: Features including cytopenias (typically anemia), leukoerythroblastosis, and morphology of cohesive, large atypical cells in aspirate and biopsy, and immunohistochemical expression for S100, Melan A, and HMB45 were present in patients with metastatic melanoma. BRAF V600E immunohistochemistry is useful as a surrogate marker of molecular results. Regardless of clinical history, at the time of the bone marrow biopsies, hematologic malignancies are in the main differential diagnosis and very rarely included metastatic melanoma, likely due to the under-recognized metastatic potential of melanoma to the bone marrow.

The Value of 18F-FDG PET/CT in Detecting Bone Marrow Involvement in Childhood Cancers.

BACKGROUND: The aim of this study was to assess the utility of F-fluoro-2-deoxy-D-glucose (F-FDG) positron emission tomography/computed tomography (PET/CT) in assessing bone marrow involvement (BMI) compared with bone marrow biopsy (BMB) in the initial staging of pediatric patients with non-Hodgkin lymphoma (NHL), Hodgkin lymphoma (HL), Ewing sarcoma (ES), and neuroblastoma (NB). PROCEDURE: A total of 94 patients (57 boys, 37 girls, median age 7 y, range 1 to 18 y) with newly diagnosed NHL, HL, ES, and NB between July 2014 and December 2017, who underwent BMB and F-FDG PET/CT before chemotherapy were included in this study. There were 36 patients with NHL, 27 HL, 16 ES, and 15 NB. F-FDG PET/CT and BMB results were reviewed and compared retrospectively. FINDINGS: Retrospective analysis of data from 94 pediatric patients (57 boys, 37 girls, median age 7 y, range 1 to 18 y) was performed. Of the 94 patients, 29 had BMI on F-FDG PET/CT. BMB was positive in 14, negative in 13, and insufficient in 2 of these 29 patients. In 65 patients negative on F-FDG PET/CT, BMB was also negative in 54 and insufficient in 7. For the whole group, sensitivity, specificity, and positive and negative predictive values of F-FDG PET/CT in detecting bone marrow metastasis at the time of diagnosis were 90.6%, 100%, 100%, and 95.4% and those of BMB were 53.1%, 87.1%, 94.4%, and 80.6%, respectively. CONCLUSION: Our study demonstrates that F-FDG PET/CT predicts BMI better than BMB. F-FDG PET/CT may be used at initial staging of pediatric patients with NHL, HL, ES, and NB.

High cortactin expression in B-cell acute lymphoblastic leukemia is associated with increased transendothelial migration and bone marrow relapse.

Cancer is a major cause of death in children worldwide, with B-lineage cell acute lymphoblastic leukemia (B-ALL) being the most frequent childhood malignancy. Relapse, treatment failure and organ infiltration worsen the prognosis, warranting a better understanding of the implicated mechanisms. Cortactin is an actin-binding protein involved in cell adhesion and migration that is overexpressed in many solid tumors and in adult B-cell chronic lymphocytic leukemia. Here, we investigated cortactin expression and potential impact on infiltration and disease prognosis in childhood B-ALL. B-ALL cell lines and precursor cells from bone marrow (BM) and cerebrospinal fluid (CSF) of B-ALL patients indeed overexpressed cortactin. In CXCL12-induced transendothelial migration assays, transmigrated B-ALL cells had highest cortactin expression. In xenotransplantation models, only cortactinhigh-leukemic cells infiltrated lungs, brain, and testis; and they colonized more easily hypoxic BM organoids. Importantly, cortactin-depleted B-ALL cells were significantly less efficient in transendothelial migration, organ infiltration and BM colonization. Clinical data highlighted a significant correlation between high cortactin levels and BM relapse in drug-resistant high-risk B-ALL patients. Our results emphasize the importance of cortactin in B-ALL organ infiltration and BM relapse and its potential as diagnostic tool to identify high-risk patients and optimize their treatments.

Histiocytic cell neoplasms involving the bone marrow: summary of the workshop cases submitted to the 18th Meeting of the European Association for Haematopathology (EAHP) organized by the European Bone Marrow Working Group, Basel 2016.

The bone marrow is a preferential site for both reactive and neoplastic histiocytic proliferations. The differential diagnosis ranges from reactive histiocyte hyperplasia in systemic infections, vaccinations, storage diseases, post myeloablative therapy, due to increased cell turnover, and in hemophagocytic lymphohistiocytosis, through extranodal Rosai-Dorfman disease to neoplasms derived from histiocytes, including histiocytic sarcomas (HS), Langerhans cell histiocytoses (LCH), Erdheim-Chester disease (ECD), and disseminated juvenile xanthogranuloma (JXG). One of the most important recent developments in understanding the biology of histiocytic neoplasms and in contributing to diagnosis was the detection of recurrent mutations of genes of the Ras/Raf/MEK/ERK signaling pathway, in particular the BRAFV600E mutation, in LCH and ECD. Here, we summarize clinical and pathological findings of 17 histiocytic neoplasms that were presented during the bone marrow symposium and workshop of the 18th European Association for Haematopathology (EAHP) meeting held in Basel, Switzerland, in 2016. A substantial proportion of these histiocytic neoplasms was combined with clonally related lymphoid (n = 2) or myeloid diseases (n = 5, all ECD). Based on the latter observation, we suggest excluding co-existent myeloid neoplasms at initial staging of elderly ECD patients. The recurrent nature of Ras/Raf/MEK/ERK signaling pathway mutations in histiocytic neoplasms was confirmed in 6 of the 17 workshop cases, illustrating their diagnostic significance and suggesting apotential target for tailored treatments.