The endocrine disruptor cadmium modulates the androgen-estrogen receptors ratio and induces inflammatory cytokines in luminal (A) cell models of breast cancer

PURPOSE

Breast cancer (BC) is the most common malignancy that affects women, and it is, to date, their leading cause of death. Luminal A molecular subtype accounts for 40% of BC and is characterized by hormone receptors positive/human epidermal growth factor 2 expression and current treatment consists of surgery plus aromatase inhibitor therapy. Interestingly, several studies demonstrated that the heavy metal cadmium (Cd), classified as a group 1 human carcinogen and widely spread in the environment, exerts estrogen-like activities in several tissues and suggested an intriguing relationship between increased Cd exposure and BC incidence. Thus, aim of this study was to evaluate effects of Cd on Luminal A BC estrogen receptor (ER) positive/progesterone receptor positive cell models in vitro to characterize the mechanism(s) involved in breast cell homeostasis disruption.

METHODS

T47D and MCF7 were exposed to Cd (0.5-1 µM) for 6-24 h to evaluate potential alterations in: cells viability, steroid receptors and intracellular signaling by western blot. Moreover, we evaluated the expression of inflammatory cytokines interleukin by RT-PCR.

RESULTS

Our results showed a significant induction of androgen receptor (AR) and an increased AR/ER ratio. Further, Cd exposure increased pro-inflammatory cytokines interleukin (IL)6, IL8 and tumor necrosis factor α levels. Finally, as previously demonstrated by our group, Cd alters pathways such as mitogen-activated protein kinase family and protein kinase B.

CONCLUSION

In conclusion, our study demonstrates that Cd modifies the expression and pattern of ERs and AR in BC cell lines, suggesting an alteration of BC cells homeostasis, likely predisposing to a carcinogenetic microenvironment.

The inhibition of IRE1alpha/XBP1 axis prevents EBV-driven lymphomagenesis in NSG mice

IMPORTANCE

The novelty of this study lies in the fact that it shows that IRE1 alpha endoribonuclease inhibition by 4μ8C was able to counteract Epstein-Barr virus-driven lymphomagenesis in NOD SCID gamma mice and prevent B-cell immortalization in vitro, unveiling that this drug may be a promising therapeutic approach to reduce the risk of post-transplant lymphoproliferative disorders (PTLD) onset in immune-deficient patients. This hypothesis is further supported by the fact that 4μ8C impaired the survival of PTLD-like cells derived from mice, meaning that it could be helpful also in the case in which there is the possibility that these malignancies have begun to arise.

Circulating miR-26b-5p and miR-451a as diagnostic biomarkers in medullary thyroid carcinoma patients

PURPOSE/METHODS

The determination of tumour biomarkers is paramount to advancing personalized medicine, more so in rare tumours like medullary thyroid carcinoma (MTC), whose diagnosis is still challenging. The aim of this study was to identify non-invasive circulating biomarkers in MTC. To achieve this goal, paired MTC tissue and plasma extracellular vesicle samples were collected from multiple centres and microRNA (miRNA) expression levels were evaluated.

RESULTS

The samples from a discovery cohort of 23 MTC patients were analysed using miRNA arrays. Lasso logistic regression analysis resulted in the identification of a set of circulating miRNAs as diagnostic biomarkers. Among them, miR-26b-5p and miR-451a, were highly expressed and their expression decreased during follow-up in disease-free patients in the discovery cohort. Circulating miR-26b-5p and miR-451a were validated using droplet digital PCR in a second independent cohort of 12 MTC patients.

CONCLUSION

This study allowed the identification and validation of a signature of two circulating miRNAs, miR-26b-5p and miR-451a, in two independent cohorts reporting a significant diagnostic performance for MTC. The results of this study offer advancements in molecular diagnosis of MTC proposing a novel non-invasive tool to use in precision medicine.

Network analysis identifies circulating miR-155 as predictive biomarker of type 2 diabetes mellitus development in obese patients: a pilot study

Obesity is the main risk factor for many non-communicable diseases. In clinical practice, unspecific markers are used for the determination of metabolic alterations and inflammation, without allowing the characterization of subjects at higher risk of complications. Circulating microRNAs represent an attractive approach for early screening to identify subjects affected by obesity more at risk of developing connected pathologies. The aim of this study was the identification of circulating free and extracellular vesicles (EVs)-embedded microRNAs able to identify obese patients at higher risk of type 2 diabetes (DM2). The expression data of circulating microRNAs derived from obese patients (OB), with DM2 (OBDM) and healthy donors were combined with clinical data, through network-based methodology implemented by weighted gene co-expression network analysis. The six circulating microRNAs overexpressed in OBDM patients were evaluated in a second group of patients, confirming the overexpression of miR-155-5p in OBDM patients. Interestingly, the combination of miR-155-5p with serum levels of IL-8, Leptin and RAGE was useful to identify OB patients most at risk of developing DM2. These results suggest that miR-155-5p is a potential circulating biomarker for DM2 and that the combination of this microRNA with other inflammatory markers in OB patients can predict the risk of developing DM2.

HHV-6A Infection of Papillary Thyroid Cancer Cells Induces Several Effects Related to Cancer Progression

Recent studies have shown that thyrocytes are permissive to HHV-6A infection and that the virus may contribute to the pathogenesis of autoimmune thyroiditis. Thyroid autoimmune diseases increase the risk of papillary cancer, which is not surprising considering that chronic inflammation activates pathways that are also pro-oncogenic. Moreover, in this condition, cell proliferation is stimulated as an attempt to repair tissue damage caused by the inflammatory process. Interestingly, it has been reported that the well-differentiated papillary thyroid carcinoma (PTC), the less aggressive form of thyroid tumor, may progress to the more aggressive follicular thyroid carcinoma (FTC) and eventually to the anaplastic thyroid carcinoma (ATC), and that to such progression contributes the presence of an inflammatory/immune suppressive tumor microenvironment. In this study, we investigated whether papillary tumor cells (BCPAP) could be infected by human herpes virus-6A (HHV-6A), and if viral infection could induce effects related to cancer progression. We found that the virus dysregulated the expression of several microRNAs, such as miR-155, miR-9, and the miR-221/222 cluster, which are involved in different steps of carcinogenesis, and increased the secretion of pro-inflammatory cytokines, particularly IL-6, which may also sustain thyroid tumor cell growth and promote cancer progression. Genomic instability and the expression of PTEN, reported to act as an oncogene in mutp53-carrying cells such as BCPAP, also increased following HHV-6A-infection. These findings suggest that a ubiquitous herpesvirus such as HHV-6A, which displays a marked tropism for thyrocytes, could be involved in the progression of PTC towards more aggressive forms of thyroid tumor.

Circulating cell-free DNA (cfDNA) in patients with medullary thyroid carcinoma is characterized by specific fragmentation and methylation changes with diagnostic value

Medullary Thyroid Carcinoma (MTC) is a rare neuroendocrine tumour whose diagnosis includes evaluating calcitonin serum levels, which can present fluctuations unrelated to MTC. Here, we investigated circulating DNA fragmentation and methylation changes as potential biomarkers using ddPCR on cell-free DNA (cfDNA) isolated from the plasma of MTC patients. For cfDNA fragmentation analysis, we investigated the fragment size distribution of a gene family and calculated short fragment fraction (SFF). Methylation analyses evaluated the methylation levels of CG_16698623, a CG dinucleotide in the MGMT gene that we found hypermethylated in MTC tissues by analyzing public databases. The SFF ratio and methylation of CG_16698623 were significantly increased in plasma from MTC patients at diagnosis, and patients with clinical remission or stable disease at follow-up showed no significant SFF difference compared with healthy subjects. Our data support the diagnostic value of cfDNA traits that could enable better management of MTC patients.

Targeting FGFRs by pemigatinib induces G1 phase cell cycle arrest, cellular stress and upregulation of tumor suppressor microRNAs

BACKGROUND

Fibroblast growth factor receptor (FGFR) gene family alterations are found in several cancers, indicating their importance as potential therapeutic targets. The FGFR-tyrosine kinase inhibitor (TKI) pemigatinib has been introduced in the treatment of advanced cholangiocarcinoma and more recently for relapsed or refractory myeloid/lymphoid neoplasms with FGFR2 and FGFR1 rearrangements, respectively. Several clinical trials are currently investigating the possible combination of pemigatinib with immunotherapy. In this study, we analyzed the biological and molecular effects of pemigatinib on different cancer cell models (lung, bladder, and gastric), which are currently objective of clinical trial investigations.

METHODS

NCI-H1581 lung, KATO III gastric and RT-112 bladder cancer cell lines were evaluated for FGFR expression by qRT-PCR and Western blot. Cell lines were treated with Pem and then characterized for cell proliferation, apoptosis, production of intracellular reactive oxygen species (ROS), and induction of senescence. The expression of microRNAs with tumor suppressor functions was analyzed by qRT-PCR, while modulation of the proteins coded by their target genes was evaluated by Western blot and mRNA. Descriptive statistics was used to analyze the various data and student's t test to compare the analysis of two groups.

RESULTS

Pemigatinib exposure triggered distinct signaling pathways and reduced the proliferative ability of all cancer cells, inducing G1 phase cell cycle arrest and strong intracellular stress resulting in ROS production, senescence and apoptosis. Pemigatinib treatment also caused the upregulation of microRNAs (miR-133b, miR-139, miR-186, miR-195) with tumor suppressor functions, along with the downregulation of validated protein targets with oncogenic roles (c-Myc, c-MET, CDK6, EGFR).

CONCLUSIONS

These results contribute to clarifying the biological effects and molecular mechanisms mediated by the anti-FGFR TKI pemigatinib in distinct tumor settings and support its exploitation for combined therapies.

Molecular mechanisms of the tyrosine kinase inhibitor pralsetinib activity in in-vitro models of medullary thyroid carcinoma: Aberrant activation of the HH-Gli signaling pathway in acquired resistance

Medullary thyroid carcinoma (MTC) is a malignant tumor with challenging management. Multi-targeted kinase inhibitors (MKI) and tyrosine-kinase inhibitors (TKI) with high specificity for RET protein are approved for advanced MTC treatment. However, their efficacy is hindered by evasion mechanisms of tumor cells. Thus, the aim of this study was the identification of an escape mechanism in MTC cells exposed to a highly selective RET TKI. TT cells were treated with TKI, MKI, and/or the HH-Gli inhibitors, GANT61 and Arsenic Trioxide (ATO), in the presence or absence of hypoxia. RET modifications, oncogenic signaling activation, proliferation and apoptosis were assessed. Additionally, cell modifications and HH-Gli activation were also evaluated in pralsetinib-resistant TT cells. Pralsetinib inhibited RET autophosphorylation and RET downstream pathways activation in normoxic and hypoxic conditions. Additionally, pralsetinib impaired proliferation, induced the activation of apoptosis and, in hypoxic cells, downregulated HIF-1α. Focusing on escape molecular mechanisms associated with therapy, we observed increased Gli1 levels in a subset of cells. Indeed, pralsetinib stimulated the re-localization of Gli1 into the cell nuclei. Treatment of TT cells with both pralsetinib and ATO resulted in Gli1 down-regulation and impaired cell viability. Moreover, pralsetinib-resistant cells confirmed Gli1 activation and up-regulation of its transcriptionally regulated target genes. Altogether, we showed that pralsetinib impairs MTC cell growth and induces cell death, also in hypoxic conditions. The HH-Gli pathway is a new molecular mechanism of escape to pralsetinib therapy that can be overcome through combined therapy.

A diagnostic circulating miRNA signature as orchestrator of cell invasion via TKS4/TKS5/EFHD2 modulation in human gliomas

BACKGROUND

Altered microRNA profiles have been observed not only in tumour tissues but also in biofluids, where they circulate in a stable form thus representing interesting biomarker candidates. This study aimed to identify a microRNA signature as a non-invasive biomarker and to investigate its impact on glioma biology.

METHODS

MicroRNAs were selected using a global expression profile in preoperative serum samples from 37 glioma patients. Comparison between serum samples from age and gender-matched controls was performed by using the droplet digital PCR. The ROC curve and Kaplan-Meier survival analyses were used to evaluate the diagnostic/prognostic values. The functional role of the identified signature was assessed by gain/loss of function strategies in glioma cells.

RESULTS

A three-microRNA signature (miR-1-3p/-26a-1-3p/-487b-3p) was differentially expressed in the serum of patients according to the isocitrate dehydrogenase (IDH) genes mutation status and correlated with both patient Overall and Progression Free Survival. The identified signature was also downregulated in the serum of patients compared to controls. Consistent with these results, the signature expression and release in the conditioned medium of glioma cells was lower in IDH-wild type cells compared to the mutated counterpart. Furthermore, in silico analysis of glioma datasets showed a consistent deregulation of the signature according to the IDH mutation status in glioma tumour tissues. Ectopic expression of the signature negatively affects several glioma functions. Notably, it impacts the glioma invasive phenotype by directly targeting the invadopodia-related proteins TKS4, TKS5 and EFHD2.

CONCLUSIONS

We identified a three microRNA signature as a promising complementary or even an independent non-invasive diagnostic/prognostic biomarker. The signature displays oncosuppressive functions in glioma cells and impacts on proteins crucial for migration and invasion, providing potential targets for therapeutic intervention.

β-arrestin1-E2F1-ac axis regulates physiological apoptosis and cell cycle exit in cellular models of early postnatal cerebellum

Development of the cerebellum is characterized by rapid proliferation of cerebellar granule cell precursors (GCPs) induced by paracrine stimulation of Sonic hedgehog (Shh) signaling from Purkinje cells, in the external granular layer (EGL). Then, granule cell precursors differentiate and migrate into the inner granular layer (IGL) of the cerebellum to form a terminally differentiated cell compartment. Aberrant activation of Sonic hedgehog signaling leads to granule cell precursors hyperproliferation and the onset of Sonic hedgehog medulloblastoma (MB), the most common embryonal brain tumor. β-arrestin1 (ARRB1) protein plays an important role downstream of Smoothened, a component of the Sonic hedgehog pathway. In the medulloblastoma context, β-arrestin1 is involved in a regulatory axis in association with the acetyltransferase P300, leading to the acetylated form of the transcription factor E2F1 (E2F1-ac) and redirecting its activity toward pro-apoptotic gene targets. This axis in the granule cell precursors physiological context has not been investigated yet. In this study, we demonstrate that β-arrestin1 has antiproliferative and pro-apoptotic functions in cerebellar development. β-arrestin1 silencing increases proliferation of Sonic hedgehog treated-cerebellar precursor cells while decreases the transcription of E2F1-ac pro-apoptotic targets genes, thus impairing apoptosis. Indeed, chromatin immunoprecipitation experiments show a direct interaction between β-arrestin1 and the promoter regions of the pro-apoptotic E2F1 target gene and P27, indicating the double role of β-arrestin1 in controlling apoptosis and cell cycle exit in a physiological context. Our data elucidate the role of β-arrestin1 in the early postnatal stages of cerebellar development, in those cell compartments that give rise to medulloblastoma. This series of experiments suggests that the physiological function of β-arrestin1 in neuronal progenitors is to directly control, cooperating with E2F1 acetylated form, transcription of pro-apoptotic genes.

A novel microRNA signature for the detection of melanoma by liquid biopsy

BACKGROUND

Melanoma is the deadliest form of skin cancer and metastatic disease is associated with a significant survival rate drop. There is an urgent need for consistent tumor biomarkers to scale precision medicine and reduce cancer mortality. Here, we aimed to identify a melanoma-specific circulating microRNA signature and assess its value as a diagnostic tool.

METHODS

The study consisted of a discovery phase and two validation phases. Circulating plasma extracellular vesicles (pEV) associated microRNA profiles were obtained from a discovery cohort of metastatic melanoma patients and normal subjects as controls. A pEV-microRNA signature was obtained using a LASSO penalized logistic regression model. The pEV-microRNA signature was subsequently validated both in a publicly available dataset and in an independent internal cohort.

RESULTS

We identified and validated in three independent cohorts a panel of melanoma-specific circulating microRNAs that showed high accuracy in differentiating melanoma patients from healthy subjects with an area under the curve (AUC) of 1.00, 0.94 and 0.75 respectively. Investigation of the function of the pEV-microRNA signature evidenced their possible immune suppressive role in melanoma patients.

CONCLUSIONS

We demonstrate that a blood test based on circulating microRNAs can non-invasively detect melanoma, offering a novel diagnostic tool for improving standard care. Moreover, we revealed an immune suppressive role for melanoma pEV-microRNAs.

Circulating microRNAs as clinically useful biomarkers for Type 2 Diabetes Mellitus: miRNomics from bench to bedside

Type 2 diabetes (T2D), a chronic metabolic disease, has attained the status of a global epidemic with steadily increasing incidence worldwide. Improved diagnosis, stratification and prognosis of T2D patients and the development of more effective treatments are needed. In this era of personalized medicine, the discovery and evaluation of innovative circulating biomarkers can be an effective tool for better stratification, prognosis and therapeutic selection/management of T2D patients. MicroRNAs (miRNAs), a class of small non-coding RNAs that modulate gene expression, have been investigated as potential circulating biomarkers in T2D. Several studies have investigated the expression of circulating miRNAs in T2D patients from various biological fluids, including plasma and serum, and have demonstrated their potential as diagnostic and prognostic biomarkers, as well as biomarkers of response to therapy. In this review, we provide an overview of the current state of knowledge, focusing on circulating miRNAs that have been consistently expressed in at least two independent studies, in order to identify a set of consistent biomarker candidates in T2D. The expression levels of miRNAs, correlation with clinical parameters, functional roles of miRNAs and their potential as biomarkers are reported. A systematic literature search and assessment of studies led to the selection and review of 10 miRNAs (miR-126-3p, miR-223-3p, miR-21-5p, miR-15a-5p, miR-24-3p, miR-34a-5p, miR-146a-5p, miR-148a-3p, miR-30d-5p and miR-30c-5p). We also present technical challenges and our thoughts on the potential validation of circulating miRNAs and their application as biomarkers in the context of T2D.

Reduced miR-184-3p expression protects pancreatic β-cells from lipotoxic and proinflammatory apoptosis in type 2 diabetes via CRTC1 upregulation

The loss of functional β-cell mass in type 2 diabetes (T2D) is associated with molecular events that include β-cell apoptosis, dysfunction and/or dedifferentiation. MicroRNA miR-184-3p has been shown to be involved in several β-cell functions, including insulin secretion, proliferation and survival. However, the downstream targets and upstream regulators of miR-184-3p have not been fully elucidated. Here, we show reduced miR-184-3p levels in human T2D pancreatic islets, whereas its direct target CREB regulated transcription coactivator 1 (CRTC1) was increased and protects β-cells from lipotoxicity- and inflammation-induced apoptosis. Downregulation of miR-184-3p in β-cells leads to upregulation of CRTC1 at both the mRNA and protein levels. Remarkably, the protective effect of miR-184-3p is dependent on CRTC1, as its silencing in human β-cells abrogates the protective mechanism mediated by inhibition of miR-184-3p. Furthermore, in accordance with miR-184-3p downregulation, we also found that the β-cell-specific transcription factor NKX6.1, DNA-binding sites of which are predicted in the promoter sequence of human and mouse MIR184 gene, is reduced in human pancreatic T2D islets. Using chromatin immunoprecipitation analysis and mRNA silencing experiments, we demonstrated that NKX6.1 directly controls both human and murine miR-184 expression. In summary, we provide evidence that the decrease in NKX6.1 expression is accompanied by a significant reduction in miR-184-3p expression and that reduction of miR-184-3p protects β-cells from apoptosis through a CRTC1-dependent mechanism.

MiR-1248: a new prognostic biomarker able to identify supratentorial hemispheric pediatric low-grade gliomas patients associated with progression

Background

Pediatric low-grade gliomas (pLGGs), particularly incompletely resected supratentorial tumours, can undergo progression after surgery. However to date, there are no predictive biomarkers for progression. Here, we aimed to identify pLGG-specific microRNA signatures and evaluate their value as a prognostic tool.

Methods

We identified and validated supratentorial incompletey resected pLGG-specific microRNAs in independent cohorts from four European Pediatric Neuro-Oncology Centres.

Results

These microRNAs demonstrated high accuracy in differentiating patients with or without progression. Specifically, incompletely resected supratentorial pLGGs with disease progression showed significantly higher miR-1248 combined with lower miR-376a-3p and miR-888-5p levels than tumours without progression. A significant (p < 0.001) prognostic performance for miR-1248 was reported with an area under the curve (AUC) of 1.00. We also highlighted a critical oncogenic role for miR-1248 in gliomas tumours. Indeed, high miR-1248 levels maintain low its validated target genes (CDKN1A (p21)/FRK/SPOP/VHL/MTAP) and consequently sustain the activation of oncogenic pathways.

Conclusions

Altogether, we provide a novel molecular biomarker able to successfully identify pLGG patients associated with disease progression that could support the clinicians in the decision-making strategy, advancing personalized medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-022-00389-x.

TMOD-05. GENOME-WIDE DNA METHYLATION PROFILE: A POWERFUL STRATEGY TO RECAPITULATE HETEROGENEITY OF PEDIATRIC BRAIN TUMORS IN PRIMARY CELL LINES

Background

Development of in vitro models of pediatric brain tumors (pBT) is instrumental for both understanding the contributing oncogenic molecular mechanisms and identifying and testing new therapeutic strategies. Primary cell lines should be established and managed to prevent epigenetic and genetic alterations and thus recapitulating the original tumor. DNA methylation (DM) is a stable epigenetic modification, altered in cancer and recently used to classify tumors. We aim to apply DM and Copy Number Variation (CNV) profiling to characterize pBT primary cell lines and tumors.

Methods

We investigated 34 pBT tissues from different histology paired to 52 their derived primary cultures in both 2D and 3D conditions, as stem-cells or in serum-supplemented medium, and both short and long-terms in culture. We studied 18 additional pBT-derived cell-lines, 9 organoids, 5 commercial cell-lines, and 122 pBT tissues from the same histological categories, as controls, for a total of 240 genome-wide DM profiles. We analyzed DM and CNV profiles by using Illumina EPIC-arrays. By means of a bump hunting strategy, we identified differentially methylated regions in faithful vs unfaithful cell lines, and performed a functional characterization using over-representation analysis. Results The 69% (25/36) of cells at early passages retained genetic alteration and the same DM patterns of the original tumors, with no differences related to 2D/3D methods or the presence of serum in media. The 70% (24/34) of primary cell lines analyzed at later passages (>5 or >14 days in culture) diverged from the primary tumor, the totality of those cultured with serum. All divergent cells clustered together acquiring common deregulated epigenetic signature induced by serum culture media, 2D methods and longer time in culture.

Conclusions

We have shown that global DM profiles, along with CNV analysis are useful tools to detect the recapitulation of pBT-derived primary cell-lines from the original tumor. Whatever subgroups tested, our results suggest that in vitro models should be passaged as little as possible to retain the epigenetic and genetic alterations of the tumors and thus to be considered relevant for basic and translational biology.

Upfront treatment with mTOR inhibitor everolimus in pediatric low-grade gliomas: A single-center experience

Pediatric low-grade gliomas (pLGGs) are the most frequent brain tumor in children. Adjuvant treatment, consisting in chemotherapy and radiotherapy, is often necessary if a complete surgical resection cannot be obtained. Traditional treatment approaches result in a significant long-term morbidity, with a detrimental impact on quality of life. Dysregulation of the mitogen-activated protein kinase (MAPK) pathway is the molecular hallmark of pLGGs and hyperactivation of the downstream mammalian target of rapamycin (mTOR) pathway is frequently observed. We report clinical and radiological results of front-line treatment with everolimus in 10 consecutive patients diagnosed with m-TOR positive pLGGs at the Bambino Gesù Children's Hospital in Rome, Italy. Median duration of treatment was 19 months (range from 13-60). Brain magnetic resonance imaging showed stable disease in 7 patients, partial response in 1 and disease progression in 2. Therapy-related adverse events were always reversible after dose reduction or temporary treatment interruption. To the best of our knowledge, this is the first report of everolimus treatment for chemo- and radiotherapy-naïve children with pLGG. Our results provide preliminary support, despite low sample size, for the use of everolimus as target therapy in pLGG showing lack of progression with a manageable toxicity profile.

Downregulation of miR-326 and its host gene β-arrestin1 induces pro-survival activity of E2F1 and promotes medulloblastoma growth

Persistent mortality rates of medulloblastoma (MB) and severe side effects of the current therapies require the definition of the molecular mechanisms that contribute to tumor progression. Using cultured MB cancer stem cells and xenograft tumors generated in mice, we show that low expression of miR-326 and its host gene β-arrestin1 (ARRB1) promotes tumor growth enhancing the E2F1 pro-survival function. Our models revealed that miR-326 and ARRB1 are controlled by a bivalent domain, since the H3K27me3 repressive mark is found at their regulatory region together with the activation-associated H3K4me3 mark. High levels of EZH2, a feature of MB, are responsible for the presence of H3K27me3. Ectopic expression of miR-326 and ARRB1 provides hints into how their low levels regulate E2F1 activity. MiR-326 targets E2F1 mRNA, thereby reducing its protein levels; ARRB1, triggering E2F1 acetylation, reverses its function into pro-apoptotic activity. Similar to miR-326 and ARRB1 overexpression, we also show that EZH2 inhibition restores miR-326/ARRB1 expression, limiting E2F1 pro-proliferative activity. Our results reveal a new regulatory molecular axis critical for MB progression.

Cancer Predisposition Syndromes and Medulloblastoma in the Molecular Era

Medulloblastoma is the most common malignant brain tumor in children. In addition to sporadic cases, medulloblastoma may occur in association with cancer predisposition syndromes. This review aims to provide a complete description of inherited cancer syndromes associated with medulloblastoma. We examine their epidemiological, clinical, genetic, and diagnostic features and therapeutic approaches, including their correlation with medulloblastoma. Furthermore, according to the most recent molecular advances, we describe the association between the various molecular subgroups of medulloblastoma and each cancer predisposition syndrome. Knowledge of the aforementioned conditions can guide pediatric oncologists in performing adequate cancer surveillance. This will allow clinicians to promptly diagnose and treat medulloblastoma in syndromic children, forming a team with all specialists necessary for the correct management of the other various manifestations/symptoms related to the inherited cancer syndromes.

Role of tissue and circulating microRNAs and DNA as biomarkers in medullary thyroid cancer

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor comprising hereditary or sporadic form with frequent mutations in the rearranged during transfection (RET) or RAS genes. Diagnosis is based on the presence of thyroid tumor mass with altered levels of calcitonin (Ctn) and carcinoembryonal antigen (CEA) in the serum and/or in the cytological smears from fine needle aspiration biopsies. Treatment consists of total thyroidectomy, followed by tyrosine kinase inhibitors (TKi) in case of disease persistence. During TKi treatment, Ctn and CEA levels can fluctuate regardless of tumor volume, metastasis or response to therapy. Research for more reliable non-invasive biomarkers in MTC is still underway. In this context, circulating nucleic acids, namely circulating microRNAs (miRNAs) and cell free DNA (cfDNA), have been evaluated by different research groups. Aiming to shed light on whether miRNAs and cfDNA are suitable as MTC biomarkers we searched three different databases, PubMed, Scopus, WOS and reviewed the literature. We classified 83 publications fulfilling our search criteria and summarized the results. We report data on miRNAs and cfDNA that can be evaluated for validation in independent studies and clinical application.

Chlamydia trachomatis elicits TLR3 expression but disrupts the inflammatory signaling down-modulating NFκB and IRF3 transcription factors in human Sertoli cells

Chlamydia trachomatis, the leading cause of bacterial sexually transmitted diseases worldwide, can disseminate and localize to the upper genital tract impairing reproductive function. Specifically, ascending C. trachomatis genital infection has been demonstrated to cause epididymitis or epididymo-orchitis, well-known risk factors for male infertility. C. trachomatis possesses the ability to infect primary human Sertoli cells, key elements for the spermatogenetic process and the immune protection of germ cells. Therefore, herein, we investigated the innate immune response in Sertoli cells following C. trachomatis infection, as well as its indirect effects on human spermatozoa. Specifically, we evaluated C. trachomatis mediated induction of Toll-like Receptors (TLR) 2, 3 and 4 as well as of downstream intracellular signaling molecules (NFκB and IRF3) and the levels of the related inflammatory mediators (IL-1α, IL-6, IFN-α, IFN-β and IFN-γ), in an in vitro infection model of primary human Sertoli cells. The main result of our study shows that C. trachomatis induced TLR3-mediated recognition in human Sertoli cells, accompanied by the down-modulation of NFκB and IRF3-dependent signaling pathways followed by no production of pro-inflammatory cytokines. In conclusion, our findings suggest that C. trachomatis can disrupt the innate immune response in Sertoli cells and evade intracellular killing, potentially giving rise to a long-term infection that may exert negative effects on the male reproductive system.

Hedgehog-GLI signalling promotes chemoresistance through the regulation of ABC transporters in colorectal cancer cells

Colorectal cancer (CRC) is a leading cause of cancer death. Chemoresistance is a pivotal feature of cancer cells leading to treatment failure and ATP-binding cassette (ABC) transporters are responsible for the efflux of several molecules, including anticancer drugs. The Hedgehog-GLI (HH-GLI) pathway is a major signalling in CRC, however its role in chemoresistance has not been fully elucidated. Here we show that the HH-GLI pathway favours resistance to 5-fluorouracil and Oxaliplatin in CRC cells. We identified potential GLI1 binding sites in the promoter region of six ABC transporters, namely ABCA2, ABCB1, ABCB4, ABCB7, ABCC2 and ABCG1. Next, we investigated the binding of GLI1 using chromatin immunoprecipitation experiments and we demonstrate that GLI1 transcriptionally regulates the identified ABC transporters. We show that chemoresistant cells express high levels of GLI1 and of the ABC transporters and that GLI1 inhibition disrupts the transporters up-regulation. Moreover, we report that human CRC tumours express high levels of the ABCG1 transporter and that its expression correlates with worse patients' prognosis. This study identifies a new mechanism where HH-GLI signalling regulates CRC chemoresistance features. Our results indicate that the inhibition of Gli1 regulates the ABC transporters expression and therefore should be considered as a therapeutic option in chemoresistant patients.

BRAF mutant colorectal cancer: ErbB2 expression levels as predictive factor for the response to combined BRAF/ErbB inhibitors

BACKGROUND

Colorectal cancer (CRC) is a heterogeneous disease with a complex biology and a wide number of altered genes such as BRAF, KRAS and PIK3CA. Advances with new-targeted therapies have been achieved and available treating options have prolonged patient's survival. However, BRAF-mutated CRC patients remain unresponsive to available therapies with RAF inhibitors (RAFi) alone or combined with ErbB inhibitors (ErbBi). These unmet needs require further exploitation of oncogenic signaling in order to set up individualized treatments.

METHODS

To this end, we tested the efficacy of single agent or combined treatments using the BRAFi, vemurafenib and two different ErbBi: panitumumab and afatinib in CRC cells characterized by different molecular phenotypes.

RESULTS

Combination strategies with BRAFi and ErbBi achieved a better response in BRAFV600E mutated cells expressing high levels of ErbB2.

CONCLUSIONS

Our findings support the importance of ErbB2 evaluation in BRAF-mutated CRC patients and its role as a positive predictor factor of response to BRAFi/ErbBi combination.

Phenotypic transitions enacted by simulated microgravity do not alter coherence in gene transcription profile

Cells in simulated microgravity undergo a reversible morphology switch, causing the appearance of two distinct phenotypes. Despite the dramatic splitting into an adherent-fusiform and a floating-spherical population, when looking at the gene-expression phase space, cell transition ends up in a largely invariant gene transcription profile characterized by only mild modifications in the respective Pearson's correlation coefficients. Functional changes among the different phenotypes emerging in simulated microgravity using random positioning machine are adaptive modifications-as cells promptly recover their native phenotype when placed again into normal gravity-and do not alter the internal gene coherence. However, biophysical constraints are required to drive phenotypic commitment in an appropriate way, compatible with physiological requirements, given that absence of gravity foster cells to oscillate between different attractor states, thus preventing them to acquire a exclusive phenotype. This is a proof-of-concept of the adaptive properties of gene-expression networks supporting very different phenotypes by coordinated 'profile preserving' modifications.

KCTD15 inhibits the Hedgehog pathway in Medulloblastoma cells by increasing protein levels of the oncosuppressor KCASH2

Medulloblastoma (MB) is the most common malignant childhood brain tumor. About 30% of all MBs belong to the I molecular subgroup, characterized by constitutive activation of the Sonic Hedgehog (Hh) pathway. The Hh pathway is involved in several fundamental processes during embryogenesis and in adult life and its deregulation may lead to cerebellar tumorigenesis. Indeed, Hh activity must be maintained via a complex network of activating and repressor signals. One of these repressor signals is KCASH2, belonging to the KCASH family of protein, which acts as negative regulators of the Hedgehog signaling pathway during cerebellar development and differentiation. KCASH2 leads HDAC1 to degradation, allowing hyperacetylation and inhibition of transcriptional activity of Gli1, the main effector of the Hh pathway. In turn, the KCASH2 loss leads to persistent Hh activity and eventually tumorigenesis. In order to better characterize the physiologic role and modulation mechanisms of KCASH2, we have searched through a proteomic approach for new KCASH2 interactors, identifying Potassium Channel Tetramerization Domain Containing 15 (KCTD15). KCTD15 is able to directly interact with KCASH2, through its BTB/POZ domain. This interaction leads to increase KCASH2 stability which implies a reduction of the Hh pathway activity and a reduction of Hh-dependent MB cells proliferation. Here we report the identification of KCTD15 as a novel player in the complex network of regulatory proteins, which modulate Hh pathway, this could be a promising new target for therapeutic approach against MB.

Low Expression of miR-466f-3p Sustains Epithelial to Mesenchymal Transition in Sonic Hedgehog Medulloblastoma Stem Cells Through Vegfa-Nrp2 Signaling Pathway

High-throughput analysis has improved the knowledge of medulloblastoma (MB), the leading cause of cancer related death in children, allowing a better comprehension of the key molecular pathways in MB pathogenesis. However, despite these advances, 30% of patients still die from the disease and survivors face severe long-term side effects. Cancer stem cells (CSCs) represent a subset of cells that not only drive tumorigenesis, but are also one of the main determinants of chemoresistance. Epithelial mesenchymal transition (EMT) is a hallmark of cancer and up to now few data is available in MB. To give insight into the role of the EMT process in maintaining the mesenchymal phenotype of CSCs, we analyzed the expression of EMT related transcripts and microRNAs in these cells. We firstly isolated CSCs from Sonic Hedgehog (SHH) MB derived from Ptch1 heterozygous mice and compared their expression level of EMT-related transcripts and microRNAs with cerebellar NSCs. We identified two molecules linked to SHH and EMT, Vegfa and its receptor Nrp2, over-expressed in SHH MB CSCs. Inhibition of Vegfa showed impairment of cell proliferation and self-renewal ability of CSCs concurrent with an increase of the expression of the EMT gene, E-cadherin, and a decrease of the EMT marker, Vimentin. Moreover, among deregulated microRNAs, we identified miR-466f-3p, a validated inhibitor of both Vegfa and Nrp2. These results allowed us to describe a new EMT molecular network, involving the down-regulation of miR-466f-3p together with the concordant up-regulation of Vegfa and Nrp2, that sustains the mesenchymal phenotype of SHH MB CSCs.

The long noncoding RNA linc-NeD125 controls the expression of medulloblastoma driver genes by microRNA sponge activity

Long noncoding RNAs (lncRNAs) are major regulators of physiological and disease-related gene expression, particularly in the central nervous system. Dysregulated lncRNA expression has been documented in several human cancers, and their tissue-specificity makes them attractive candidates as diagnostic/prognostic biomarkers and/or therapeutic agents. Here we show that linc-NeD125, which we previously characterized as a neuronal-induced lncRNA, is significantly overexpressed in Group 4 medulloblastomas (G4 MBs), the largest and least well characterized molecular MB subgroup. Mechanistically, linc-NeD125 is able to recruit the miRNA-induced silencing complex (miRISC) and to directly bind the microRNAs miR-19a-3p, miR-19b-3p and miR-106a-5p. Functionally, linc-NeD125 acts as a competing endogenous RNA (ceRNA) that, sequestering the three miRNAs, leads to de-repression of their targets CDK6, MYCN, SNCAIP, and KDM6A, which are major driver genes of G4 MB. Accordingly, linc-NeD125 downregulation reduces G4 cell proliferation. Moreover, we also provide evidence that linc-NeD125 ectopic expression in the aggressive Group 3 MB cells attenuates their proliferation, migration and invasion.This study unveils the first lncRNA-based ceRNA network in central nervous system tumours and provides a novel molecular circuit underlying the enigmatic Group 4 medulloblastoma.

The miR-139-5p regulates proliferation of supratentorial paediatric low-grade gliomas by targeting the PI3K/AKT/mTORC1 signalling

AIMS

Paediatric low-grade gliomas (pLGGs) are a heterogeneous group of brain tumours associated with a high overall survival: however, they are prone to recur and supratentorial lesions are difficult to resect, being associated with high percentage of disease recurrence. Our aim was to shed light on the biology of pLGGs.

METHODS

We performed microRNA profiling on 45 fresh-frozen grade I tumour samples of various histological classes, resected from patients aged ≤16 years. We identified 93 microRNAs specifically dysregulated in tumours as compared to non-neoplastic brain tissue. Pathway analysis of the microRNAs signature revealed PI3K/AKT signalling as one of the centrally enriched oncogenic signalling. To date, activation of the PI3K/AKT pathway in pLGGs has been reported, although activation mechanisms have not been fully investigated yet.

RESULTS

One of the most markedly down-regulated microRNAs in our supratentorial pLGGs cohort was miR-139-5p, whose targets include the gene encoding the PI3K's (phosphatidylinositol 3-kinase) catalytic unit, PIK3CA. We investigated the role of miR-139-5p in regulating PI3K/AKT signalling by the use of human cell cultures derived from supratentorial pLGGs. MiR-139-5p overexpression inhibited pLGG cell proliferation and decreased the phosphorylation of PI3K target AKT and phosphorylated-p70 S6 kinase (p-p70 S6K), a hallmark of PI3K/AKT/mTORC1 signalling activation. The effect of miR-139-5p was mediated by PI3K inhibition, as suggested by the decrease in proliferation and phosphorylation of AKT and p70 S6K after treatment with the direct PI3K inhibitor LY294002.

CONCLUSIONS

These findings provide the first evidence that down-regulation of miR-139-5p in supratentorial pLGG drives cell proliferation by derepressing PI3K/AKT signalling.

Circulating MicroRNAs in Elderly Type 2 Diabetic Patients

The circulating microRNAs (miRNAs) associated with type 2 diabetes (T2D) in elderly patients are still being defined. To identify novel miRNA biomarker candidates for monitoring responses to sitagliptin in such patients, we prospectively studied 40 T2D patients (age > 65) with HbA1c levels of 7.5-9.0% on metformin. After collection of baseline blood samples (t₀), the dipeptidyl peptidase-IV (DPP-IV) inhibitor (DPP-IVi) sitagliptin was added to the metformin regimen, and patients were followed for 15 months. Patients with HbA1c < 7.5% or HbA1c reduction > 0.5% after 3 and 15 months of therapy were classified as "responders" (group R, n = 34); all others were classified as "nonresponders" (group NR, n = 6). Circulating miRNA profiling was performed on plasma collected in each group before and after 15 months of therapy (t₀ and t₁₅). Intra- and intergroup comparison of miRNA profiles pinpointed three miRNAs that correlated with responses to sitagliptin: miR-378, which is a candidate biomarker of resistance to this DPP-IVi, and miR-126-3p and miR-223, which are associated with positive responses to the drug. The translational implications are as immediate as evident, with the possibility to develop noninvasive diagnostic tools to predict drug response and development of chronic complications.

Numb Isoforms Deregulation in Medulloblastoma and Role of p66 Isoform in Cancer and Neural Stem Cells

Numb is an intracellular protein with multiple functions. The two prevalent isoforms, Numb p66 and Numb p72, are regulators of differentiation and proliferation in neuronal development. Additionally, Numb functions as cell fate determinant of stem cells and cancer stem cells and its abnormal expression has been described in several types of cancer. Involvement of deregulated Numb expression has been described in the malignant childhood brain tumor medulloblastoma, while Numb isoforms in these tumors and in cancer stem-like cells derived from them, have not been studied to date. Here we show that medulloblastoma stem-like cells and cerebellar neuronal stem cells (NSCs) express Numb p66 where its expression tampers stemness features. Furthermore, medulloblastoma samples evaluated in this study express decreased levels of Numb p66 while overexpressed Numb p72 compared with normal tissues. Our results uncover different roles for the two major Numb isoforms examined in medulloblastoma and a critical role for Numb p66 in regulating stem-like cells and NSCs maintenance.

The histone methyltransferase EZH2 as a druggable target in SHH medulloblastoma cancer stem cells

The histone methyltransferase EZH2 plays a role in maintenance of the stem component of cancer, and its overexpression and/or mutation typically drives tumor aggressiveness, drug resistance and patients’ poor prognosis. In this study, we use mouse and human medulloblastoma stem-like cells belonging to the Sonic Hedgehog subgroup (SHH MB-SLCs) and demonstrate that genetic suppression of EZH2 reduces the level of its histone mark H3K27me3 and lowers proliferation and self-renewal. We designed an EZH2 inhibitor (EZH2i) as a simplified analog of EPZ005687 and GSK2816126, MC3629, and we tested its biological activity in SHH MB-SLCs. Pharmacological inhibition of EZH2 impairs SHH MB cells proliferation and self-renewal, and induces apoptosis in vitro. Finally, we generated xenograft MB-SLCs orthotopic tumors in nude mice to test MC3629 in vivo. In treated mice, we observed impairment of tumor growth, together with induction of apoptosis and reduction of proliferation and stemness.

Overall, these findings describe EZH2 as a druggable target in MB and provide insight into the biological activity of MC3629 as an EZH2i.

β-arrestin1-mediated acetylation of Gli1 regulates Hedgehog/Gli signaling and modulates self-renewal of SHH medulloblastoma cancer stem cells

Background

Aberrant Sonic Hedgehog/Gli (Hh/Gli) signaling pathway is a critical regulator of Sonic hedgehog medulloblastoma (SHH-MB). Cancer stem cells (CSCs), thought to be largely responsible for tumor initiation, maintenance, dissemination and relapse, have been identified in SHH-MB. Since we previously demonstrated that Hh/Gli signaling controls CSCs features in SHH-MB and that in these tumors miR-326 is down regulated, here we investigated whether there is a functional link between Hh/Gli signaling and miR-326.

Methods

We evaluated β-arrestin1 (Arrb1) and its intragenic miR-326 levels in CSCs derived from SHH-MB. Subsequently, we modulated the expression of Arrb1 and miR-326 in CSCs in order to gain insight into their biological role. We also analyzed the mechanism by which Arrb1 and miR-326 control Hh/Gli signaling and self-renewal, using luciferase and protein immunoprecipitation assays.

Results

Low levels of Arrb1 and miR-326 represent a feature of CSCs derived from SHH-MB. We observed that re-expression of Arrb1 and miR-326 inhibits Hh/Gli signaling pathway at multiple levels, which cause impaired proliferation and self-renewal, accompanied by down regulation of Nanog levels. In detail, miR-326 negatively regulates two components of the Hh/Gli pathway the receptor Smoothened (Smo) and the transcription factor Gli2, whereas Arrb1 suppresses the transcriptional activity of Gli1, by potentiating its p300-mediated acetylation.

Conclusions

Our results identify a new molecular mechanism involving miR-326 and Arrb1 as regulators of SHH-MB CSCs. Specifically, low levels of Arrb1 and miR-326 trigger and maintain Hh/Gli signaling and self-renewal.

Role of Natural Killer Cells in Sonic Hedgehog driven Medulloblastoma

Medulloblastoma (MB) is the most common paediatric neoplasm of the CNS. Standard therapy is mainly curative; however, the severe side effects make immunotherapy an attractive therapeutic option. Natural Killer (NK) cells are innate lymphoid cells that can be used for adoptive cell therapy. Herein, we studied the role of NK cells in MB growth control, focusing on Sonic Hedgehog (SHH) subgroup, using the MB cell line DAOY.

The contribution of SHH pathway on NK cell recruitment to MB was analysed performing an orthotopic xenograft of DAOY in nude mice treated with a pharmacological inhibitor of the SHH pathway. FACS analysis revealed higher percentage of NK cells in cerebella of treated mice compared to control group.

Based on this in vivo evidence, we characterized the mechanism underlying NK cell recruitment. Pharmacological inhibition of the SHH pathway in DAOY raised the expression and secretion of chemokines involved in NK cell migration. Chemotaxis assay confirmed that these secreted molecules were functional.

Successively, we assessed the ability of NK cells to recognize SHH-MB. By FACS analysis we determined the tumor line expression of ligands for the NKG2D and DNAM1 activating receptor. In particular, ULBP3 and ULBP2 were expressed at high levels.

Moreover, we found that NK cells co-culture with DAOY induced degranulation that was reduced in the presence of anti-NKG2D and anti-DNAM1 blocking antibodies, suggesting an involvement of these receptors in triggering degranulation.

Besides, DAOY increased the production of IFNγ in NK cells pre-activated of with suboptimal doses of IL12 and IL15.

Our data provide evidence for a role of NK cells in the control of SHH-MB growth.

Abstract 2484: Non-canonical Hedgehog/Gli1 signaling drives lung adenocarcinoma stem cells survival and its targeting inhibits CSC-derived tumors

Introduction: Lung Adenocarcinoma (AC) is the most frequent lung cancer histological subtype and is a leading cause of cancer-related death worldwide. Hedgehog/Gli (Hh/Gli) signaling pathway regulates lung development and its aberrant activation contributes to tumor pathogenesis and play a role in cancer stem cells (CSC) control.

We investigated oncogenic Hh/Gli signaling in AC-CSC.

Methods: human AC-CSC were derived from primary tumors. For in vitro studies AC-CSC were maintained in serum-free medium supplemented with EGF/bFGF. For in vivo experiments, immunocompromised mice were injected with AC-CSC. Gli1 inhibitor GANT61 was used both in vitro and in vivo (IP 40 mg/kg twice/we) treatments.

Results: Using mRNA datasets and tissue microarray of Non-small Cell Lung Cancer (NCSLC) samples we found that in AC Gli1 is expressed independently of its canonical activator Smoothened (Smo) expression level. Similarly, CSC were Gli1 positive regardless of Smo expression levels. Indeed, we found that SMO regulatory region is highly methylated in AC cells where Smo mRNA and protein are low.

Looking for Smo-independent regulation of GLI activity we found that NRP2/Erk and IGF1R/Erk axes regulate Gli1 in AC-CSC. Suppression of Gli1 with GANT61 in CSC resulted in impairment of cell growth and stemness features. We performed in-vivo experiments: CSC-derived xenograft from GANT61 treated mice showed impaired tumor growth, reduced proliferation and increased apoptosis. We next highlighted a tumor-stroma crosstalk. A positive autocrine oncogenic feedback loop sustains Gli1 in AC-CSC since we found that the CSC expressed NRP2 and its ligands VEGF-A and VEGF-C. A paracrine positive loop also sustain Hh/Gli signaling in AC where Cancer-Associated Fibroblasts (CAFs) harbor Hh/Gli1 canonical pathway that regulates the expression of VEGF-A, VEGF-C and IGF2 ligands of NRP2 and IGF1R respectively.

Conclusion: Our findings suggest a non-canonical activation of Hh/Gli pathway in AC. In this context, GLI1 transcription factor is effectors of NRP2/Erk and/or IGF1R/Erk signaling inputs.

Our results have implications for the understanding of AC development and sustain the inclusion of target therapy acting downstream of Smo level in the design of AC treatment.

Citation Format: Agnese Po, Marianna Silvano, Evelina Miele, Adriana Eramo, Matilde Todaro, Carlo Capalbo, Valentina Salvati, Giovanni Sette, Danilo Cucchi, Zein M. Besharat, Gianluca Canettieri, Lucia Di Marcotullio, Isabella Screpanti, Giorgio Stassi, Ruggero De Maria, Ann Zeuner, Enrico De Smaele, Elisabetta Ferretti. Non-canonical Hedgehog/Gli1 signaling drives lung adenocarcinoma stem cells survival and its targeting inhibits CSC-derived tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2484.

Anomalous vascularization in a Wnt medulloblastoma: a case report

BACKGROUND

Medulloblastoma is the most common malignant brain tumor in children. To date only few cases of medulloblastoma with hemorrhages have been reported in the literature. Although some studies speculate on the pathogenesis of this anomalous increased vascularization in medulloblastoma, the specific mechanism is still far from clearly understood. A correlation between molecular medulloblastoma subgroups and hemorrhagic features has not been reported, although recent preliminary studies described that WNT-subtype tumors display increased vascularization and hemorrhaging.

CASE PRESENTATION

Herein, we describe a child with a Wnt-medulloblastoma presenting as cerebellar-vermian hemorrhagic lesion. Brain magnetic resonance imaging (MRI) showed the presence of a midline posterior fossa mass with a cystic hemorrhagic component. The differential diagnosis based on imaging included cavernous hemangioma, arteriovenous malformation and traumatic lesion. At surgery, the tumor appeared richly vascularized as documented by the preoperative angiography.

CONCLUSIONS

The case we present showed that Wnt medulloblastoma may be associated with anomalous vascularization. Further studies are needed to elucidate if there is a link between the hypervascularization and the Wnt/β-catenin signaling activation and if this abnormal vasculature might influence drug penetration contributing to good prognosis of this medulloblastoma subgroup.

Abstract 970: Circulating microRNA signature in group 4 medulloblastoma patients

Medulloblastoma is the most common malignant brain tumor in childhood. Four main clinically and molecularly distinct MB subtypes have been identified: WNT, SHH, Group 3, and Group 4. Among them, Group 4 MB (G4MB) appears to have the most skewed age ratio, is predominant in males and shows an intermediate prognosis. In spite of being the most frequent (35%), it is also the least understood of all the subgroups. Diagnosis is based on patients’ clinical symptoms and neuro-imaging techniques with high risk of false positive and/or late tumor discovery. The early detection of the disease is essential to reduce both cancer mortality and long time therapy related toxicity. To date, there is no reliable marker for G4MB that could facilitate the early diagnosis and allow the evaluation of the response to radio and chemotherapy treatment. Therefore, the discovery of new biomarkers as a specific signature of G4MB patients, potentially useful as diagnostic factor, would be extraordinarily worthwhile.

MicroRNAs are single-stranded non coding RNA molecules of 19-24 nucleotides in length involved in the post-transcriptional regulation of gene expression, whose expression is strongly deregulated in several types of tumors. Recent studies have shown that microRNAs are released into the bloodstream and are stably detectable thanks to their association with extracellular vescicle, or complex with RNA-binding protein that protect them from RNAse degradation. The minimally invasive liquid biopsy flanked to the reliability and specificity of microRNAs in cancer detection indicates circulating microRNAs not only as promising biomarkers to get early diagnosis, but also to follow treatment response and detect recurrence.

Here we report a high-throughput screening of microRNAs in G4MB plasma samples before surgery and during follow-up. Two different approaches (DeepSeq and Low Denstity Array) were used to detect the differentially expressed circulating microRNAs in 4 patients and in 4 age- and sex- matched healthy donors. Baseline microRNA expression profiling allowed us to disclose a signature of 34 miRNAs able to identify patients versus healthy children. Moreover, selected microRNAs were validated by RT-qPCR technology on a wider cohort of G4MB patients (n = 8) and healthy donors (n = 8). Specifically, we identified two important oncogenic microRNA clusters (miR-17/92 and miR-106b/25) significantly upregulated in G4MB plasma patients. Therapy reduced the expression of these microRNAs up to levels of healthy donors.

In conclusion we identified circulating microRNA signature in G4MB.

Citation Format: Evelina Miele, Vincenzo Alfano, Zein Mersini Besharat, Giuseppina Catanzaro, Angela Mastronuzzi, Andrea Carai, Agnese Po, Luana Abballe, Antonella Cacchione, Franco Locatelli, Elisabetta Ferretti. Circulating microRNA signature in group 4 medulloblastoma patients. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 970.

Metastatic Group 3 Medulloblastoma in a Patient With Tuberous Sclerosis Complex: Case Description and Molecular Characterization of the Tumor

Medulloblastoma is the most common pediatric brain tumor. We describe a child with tuberous sclerosis complex that developed a Group 3, myc overexpressed, metastatic medulloblastoma (MB). Considering the high risk of treatment-induced malignancies, a tailored therapy, omitting radiation, was given. Based on the evidence of mammalian target of rapamycin mTORC, mTOR Complex; RAS, Rat sarcoma; RAF, rapidly accelerated fibrosarcoma (mTOR) pathway activation in the tumor, targeted therapy was applied resulting in complete remission of disease. Although the PI3K/AKT/mTOR signaling pathway plays a role in MB, we did not find TSC1/TSC2 (TSC, tuberous sclerosis complex) mutation in our patient. We speculate that a different pathway resulting in mTOR activation is the basis of both TSC and MB in this child; H&E, haematoxilin and eosin; Gd, gadolinium.

MicroRNA-124a is hyperexpressed in type 2 diabetic human pancreatic islets and negatively regulates insulin secretion

AIMS

MicroRNAs are a class of negative regulators of gene expression, which have been shown to be involved in the development of endocrine pancreas and in the regulation of insulin secretion. Since type 2 diabetes (T2D) is characterized by beta cell dysfunction, we aimed at evaluating expression levels of miR-124a and miR-375, both involved in the control of beta cell function, in human pancreatic islets obtained from T2D and from age-matched non-diabetic organ donors.

METHODS

We analyzed miR-124a and miR-375 expression by real-time qRT-PCR in human pancreatic islets and evaluated the potential role of miR-124a by overexpressing or silencing such miRNA in MIN6 pseudoislets.

RESULTS

We identified a major miR-124a hyperexpression in T2D human pancreatic islets with no differential expression of miR-375. Of note, miR-124a overexpression in MIN6 pseudoislets resulted in an impaired glucose-induced insulin secretion. In addition, miR-124a silencing in MIN6 pseudoislets resulted in increased expression of predicted target genes (Mtpn, Foxa2, Flot2, Akt3, Sirt1 and NeuroD1) involved in beta cell function. For Mtpn and Foxa2, we further demonstrated the actual binding of miR-124a to their 3UTR sequences by luciferase assay.

CONCLUSIONS

We uncovered a major hyperexpression of miR-124a in T2D islets, whose silencing resulted in increased expression of target genes of major importance for beta cell function and whose overexpression impaired glucose-stimulated insulin secretion, leading to the hypothesis that an altered miR-124a expression may contribute to beta cell dysfunction in type 2 diabetes.

Proteomic analysis of human sonic hedgehog (SHH) medulloblastoma stem-like cells

First proteomic characterization of sonic hedgehog human medulloblastoma stem-like cells.

Gli1/DNA interaction is a druggable target for Hedgehog-dependent tumors

Hedgehog signaling is essential for tissue development and stemness, and its deregulation has been observed in many tumors. Aberrant activation of Hedgehog signaling is the result of genetic mutations of pathway components or other Smo-dependent or independent mechanisms, all triggering the downstream effector Gli1. For this reason, understanding the poorly elucidated mechanism of Gli1-mediated transcription allows to identify novel molecules blocking the pathway at a downstream level, representing a critical goal in tumor biology. Here, we clarify the structural requirements of the pathway effector Gli1 for binding to DNA and identify Glabrescione B as the first small molecule binding to Gli1 zinc finger and impairing Gli1 activity by interfering with its interaction with DNA. Remarkably, as a consequence of its robust inhibitory effect on Gli1 activity, Glabrescione B inhibited the growth of Hedgehog-dependent tumor cells in vitro and in vivo as well as the self-renewal ability and clonogenicity of tumor-derived stem cells. The identification of the structural requirements of Gli1/DNA interaction highlights their relevance for pharmacologic interference of Gli signaling.

Large cell anaplastic medulloblastoma metastatic to the scalp: tumor and derived stem-like cells features

Background

Extraneural metastases (ENM) rarely occur in medulloblastoma (MBL) patients and only few cases of subcutaneous localizations have been described. ENM indicate an aggressive disease associated with a worse prognosis. The characterization of metastatic tumours might be useful to understand their pathogenesis and to identify the most appropriate therapeutic strategies.

Case presentation

We present the case of a child with Large Cell Anaplastic (LC/A) MBL, who developed multiple subcutaneous metastases in the scalp area after a ventriculo-peritoneal shunting procedure. The disease rapidly progressed and the child died despite chemotherapy and primary tumour surgical debulking.

We molecularly classified the tumour as a group 3 MBL; in addition, we derived stem-like cells (SLC) from a metastatic lesion. Primary tumour, metastases and SLC were further analysed, particularly focusing on features linked to the cutaneous dissemination. Indeed, molecules involved in angiogenesis, cell invasion and epidermal growth factor signalling resulted highly expressed.

Conclusions

The present report describes a very rare case of subcutaneous metastatic MBL. The tumour, metastases and SLC have been clinically, pathologically and molecularly characterized. Our case is an example of multidisciplinary approach aiming to characterize MBL aggressive behaviour.

High-throughput microRNA profiling of pediatric high-grade gliomas

BACKGROUND

High-grade gliomas (HGGs) account for 15% of all pediatric brain tumors and are a leading cause of cancer-related mortality and morbidity. Pediatric HGGs (pHGGs) are histologically indistinguishable from their counterpart in adulthood. However, recent investigations indicate that differences occur at the molecular level, thus suggesting that the molecular path to gliomagenesis in childhood is distinct from that of adults. MicroRNAs (miRNAs) have been identified as key molecules in gene expression regulation, both in development and in cancer. miRNAs have been investigated in adult high-grade gliomas (aHGGs), but scant information is available for pHGGs.

METHODS

We explored the differences in microRNAs between pHGG and aHGG, in both fresh-frozen and paraffin-embedded tissue, by high-throughput miRNA profiling. We also evaluated the biological effects of miR-17-92 cluster silencing on a pHGG cell line.

RESULTS

Comparison of miRNA expression patterns in formalin versus frozen specimens resulted in high correlation between both types of samples. The analysis of miRNA profiling revealed a specific microRNA pattern in pHGG with an overexpression and a proliferative role of the miR-17-92 cluster. Moreover, we highlighted a possible quenching function of miR-17-92 cluster on its target gene PTEN, together with an activation of tumorigenic signaling such as sonic hedgehog in pHGG.

CONCLUSIONS

Our results suggest that microRNA profiling represents a tool to distinguishing pediatric from adult HGG and that miR-17-92 cluster sustains pHGG.

microRNA-17-92 cluster is a direct Nanog target and controls neural stem cell through Trp53inp1

The transcription factor Nanog plays a critical role in the self-renewal of embryonic stem cells as well as in neural stem cells (NSCs). microRNAs (miRNAs) are also involved in stemness regulation. However, the miRNA network downstream of Nanog is still poorly understood. High-throughput screening of miRNA expression profiles in response to modulated levels of Nanog in postnatal NSCs identifies miR-17-92 cluster as a direct target of Nanog. Nanog controls miR-17-92 cluster by binding to the upstream regulatory region and maintaining high levels of transcription in NSCs, whereas Nanog/promoter association and cluster miRNAs expression are lost alongside differentiation. The two miR-17 family members of miR-17-92 cluster, namely miR-17 and miR-20a, target Trp53inp1, a downstream component of p53 pathway. To support a functional role, the presence of miR-17/20a or the loss of Trp53inp1 is required for the Nanog-induced enhancement of self-renewal of NSCs. We unveil an arm of the Nanog/p53 pathway, which regulates stemness in postnatal NSCs, wherein Nanog counteracts p53 signals through miR-17/20a-mediated repression of Trp53inp1.

Direct control of the miRNA-17/92 cluster enables Nanog to restrain p53 activity and thus to maintain pluripotency in neural stem cells.