Glioblastoma is thought to originate from neural stem cells (NSCs) of the subventricular zone that acquire genetic alterations. In the adult brain, NSCs are largely quiescent, suggesting that deregulation of quiescence maintenance may be a prerequisite for tumor initiation. Although inactivation of the tumor suppressor p53 is a frequent event in gliomagenesis, whether or how it affects quiescent NSCs (qNSCs) remains unclear. Here, we show that p53 maintains quiescence by inducing fatty-acid oxidation (FAO) and that acute p53 deletion in qNSCs results in their premature activation to a proliferative state. Mechanistically, this occurs through direct transcriptional induction of PPARGC1a, which in turn activates PPARα to upregulate FAO genes. Dietary supplementation with fish oil containing omega-3 fatty acids, natural PPARα ligands, fully restores quiescence of p53-deficient NSCs and delays tumor initiation in a glioblastoma mouse model. Thus, diet can silence glioblastoma driver mutations, with important implications for cancer prevention.

In the central nervous system (CNS), regulation of nuclear function has been implicated in the control of cell cycle and migratory processes during neurogenesis. Alterations of these processes can lead to neoplastic transformation of neural stem cells (NSCs) and glioblastoma multiforme (GBM). The ability of GBM cells to migrate through the brain parenchyma represents a key factor underlying GBM aggressiveness and resistance to treatment. Notably, brain cancer cells use the same routes utilized by neuroblasts/immature neurons and NSCs, suggesting a neurobiological root of brain cancer migration. However, our understanding of potentially common mechanisms regulating cell migration/invasion during neurogenesis and brain tumourigenesis remains limited. Our previous work has implicated the Promyelocytic Leukaemia protein (PML), the essential component of the PML nuclear body (PML-NB), in regulation of embryonic neurogenesis via its ability to control proliferation in NSCs. We set out to investigate the role of PML in adult neurogenesis and GBM. Loss of PML leads to impaired NSC and neuroblast migration and to a smaller olfactory bulb in the adult mouse brain. A similar migration defect is observed in primary GBM cells where PML expression has been knocked down. Mechanistically, PML controls cell migration in both mouse NSCs and primary GBM cells via down-regulation of Slit genes, which are key regulators of axon guidance during development. Changes in Slits transcription upon PML kd are caused by global reduction of the repressive H3K27me3 epigenetic mark. This is associated with its redistribution to nuclear lamina-associated domains (LADs). Finally, PML controls tumor invasion and survival in an orthotopic animal model and inversely correlates with patient prognosis in GBM. Taken together, these findings support a model whereby PML-mediated modifications of chromatin structure and function regulate cell migration during normal neurogenesis and brain tumorigenesis, suggesting a neurobiological root of brain cancer invasion.

The angiopoietin-like 4 (ANGPTL4) protein belongs to a superfamily of secreted proteins structurally related to factors modulating angiogenesis known as angiopoietins. At first, ANGPTL4 has been identified as an adipokine exclusively involved in lipid metabolism, because of its prevalent expression in liver and adipose tissue. This protein regulates lipid metabolism by inhibiting lipoprotein lipase (LPL) activity and stimulating lipolysis of white adipose tissue (WAT), resulting in increased levels of plasma triglycerides (TG) and fatty acids. Subsequently, ANGPTL4 has been shown to be involved in several nonmetabolic and metabolic conditions, both physiological and pathological, including angiogenesis and vascular permeability, cell differentiation, tumorigenesis, glucose homoeostasis, lipid metabolism, energy homeostasis, wound healing, inflammation, and redox regulation. The transcriptional regulation of ANGPTL4 can be modulated by several transcription factors, including PPAR α , PPAR β / δ , PPAR γ , and HIF-1 α , and nutritional and hormonal conditions. Several studies showed that high levels of ANGPTL4 are associated with poor prognosis in patients with various solid tumors, suggesting an important role in cancer onset and progression, metastasis, and anoikis resistance. Here, we have discussed the potential role of ANGPTL4 in mediating the cross talk between metabolic syndromes, such as diabetes and obesity, and cancer through regulation of its expression by PPARs.

INTRODUCTION: The control of SVZ neural progenitor/stem cells (NPCs) migration through the rostral migratory stream (RMS) is essential for normal neurogenesis and serve as the fundamental basis of production/replacement of neurons in the adult brain. Alterations of these processes can lead to neoplastic transformation and glioblastoma multiforme (GBM). The ability of GBM cells to migrate through the brain parenchyma represents a key factor underlying GBM aggressiveness. GBM cells use the same routes used by neuroblasts/immature neurons and neural stem cells upon injury, such as vessels and myelin tracts, suggesting that GBM migration may lay its roots in essential cellular processes controlling migration of immature neurons/neuroblasts and neural stem cells (1). However, our understanding of mechanisms regulating cell migration/invasion during brain tumourigenesis remains limited. METHODS: We combined in vivo and in vitro approaches, including the use of genetically modified mice, primary HGG tissues/NPCs (in collaboration with S Brandner, UCL, C Jones, ICR, S Pollard, Edinburgh, and others). RESULTS: Here we report that the stem cell factor and RAS effector Promyelocytic Leukaemia protein (PML) (2,3) regulates cell migration through the epigenetic control of Slit axon guidance genes in normal and neoplastic cells in the central nervous system. Loss of PML leads to impaired NSC and neuroblast migration and a smaller olfactory bulb in the adult mouse brain. PML controls cell migration via Polycomb Repressive 2-dependent regulation of the Slit axon guidance genes. A similar epigenetically controlled PML/Slit axis is functional also upon RAS-driven neoplastic transformation of NSCs and in primary GBM cells. PML expression inversely correlates with Slit1 expression and patient prognosis in GBM and is enriched in the mesenchymal subtype, which is characterized by activation of the RAS/MAPK pathway. Finally, PML loss impairs tumor growth in an orthotopic animal model. CONCLUSIONS: Taken together, these findings disclose a novel molecular axis at the root of cell migration during normal neurogenesis and brain tumourigenesis. Cuddapah VA et al. Nat Rev Neurosci 15: 455–465. Regad T. et al. Nature neuroscience 12: 132–140. Salomoni P. et al. Cell Res 18: 622–640.

Cell migration through the brain parenchyma underpins neurogenesis and glioblastoma (GBM) development. Since GBM cells and neuroblasts use the same migratory routes, mechanisms underlying migration during neurogenesis and brain cancer pathogenesis may be similar. Here, we identify a common pathway controlling cell migration in normal and neoplastic cells in the CNS. The nuclear scaffold protein promyelocytic leukemia (PML), a regulator of forebrain development, promotes neural progenitor/stem cell (NPC) and neuroblast migration in the adult mouse brain. The PML pro-migratory role is active also in transformed mouse NPCs and in human primary GBM cells. In both normal and neoplastic settings, PML controls cell migration via Polycomb repressive complex 2 (PRC2)-mediated repression of Slits, key regulators of axon guidance. Finally, a PML/SLIT1 axis regulates sensitivity to the PML-targeting drug arsenic trioxide in primary GBM cells. Taken together, these findings uncover a drug-targetable molecular axis controlling cell migration in both normal and neoplastic cells.

Zoledronic acid (ZOL), belonging to third generation bisphosphonate family, is a potent inhibitor of osteoclast-mediated bone resorption, widely used to effectively prevent osteolysis in breast cancer patients who develop bone metastases. Low doses of ZOL have been shown to exhibit a direct anticancer role, by inhibiting cell adhesion, invasion, cytoskeleton remodelling and proliferation in MCF-7 breast cancer cells. In order to identify the molecular mechanisms and signaling pathways underlying the anticancer activity exerted by ZOL, we analyzed for the first time the microRNA expression profile in breast cancer cells. A large-scale microarray analysis of 377 miRNAs was performed on MCF7 cells treated with 10 μM ZOL for 24 h compared to untreated cells. Furthermore, the expression of specific ZOL-induced miRNAs was analyzed in MCF-7 and SkBr3 cells through Real-time PCR. Low-dose treatment with ZOL significantly altered expression of 54 miRNAs. Nine upregulated and twelve downregulated miRNAs have been identified after 24 h of treatment. Also, ZOL induced expression of 11 specific miRNAs and silenced expression of 22 miRNAs. MiRNA data analysis revealed the involvement of differentially expressed miRNAs in PI3K/Akt, MAPK, Wnt, TGF-β, Jak-STAT and mTOR signaling pathways, and regulation of actin cytoskeleton. Our results have been shown to be perfectly coherent with the recent findings reported in literature concerning changes in expression of some miRNAs involved in bone metastasis formation, progression, therapy resistance in breast cancer. In conclusion, this data supports the hypothesis that ZOL-induced modification of the miRNA expression profile contributes to the anticancer efficacy of this agent.

Zoledronic acid (ZOL), a third generation bisphosphonate able to significantly inhibit bone resorption, is currently used for the treatment of breast cancer patients with osteolytic bone metastases. Our previous work showed an effective anticancer role of low-dose ZOL in the inhibition of several processes, such as cell adhesion, invasion, cytoskeleton remodelling and proliferation, in MCF-7 breast cancer cell line. The main aim of our study was to investigate the molecular mechanisms and signaling pathways by which ZOL exerts its anti-tumor effects in breast cancer cells focusing our attention on miRNA expression profile. Using a TaqMan Low Density Array A human microRNA microarray analysis, the expression profile of 377 miRNAs was analyzed in MCF7 cells treated for 24 h with 10 µM ZOL with respect to untreated cells. In addition, the expression of miRNAs specifically induced by ZOL was analyzed in MCF-7, MDA-MB-231 and SkBr3 cells using Real-time PCR analyses. A subset of miRNAs was shown to be differentially expressed following the low-dose ZOL treatment, and several cancer-related pathways, including PI3/Akt, MAPK, Wnt, Jak-STAT, TGF-&bgr;, and mTOR signaling, were predicted as potential targets of these deregulated miRNAs, using the DIANA tool mirPath software. In particular, a set of 54 miRNAs resulted significantly altered after ZOL exposure, with a group of them being up- or down-regulated, and others induced or silenced by treatment. Most of these miRNAs are unexamined in breast cancer cells. These data are perfectly in agreement with the recent results reported in literature regarding some miRNAs involved in proliferation, bone metastasis development, invasion and therapy resistance in breast cancer. This work establishes, for the first time, a link between anticancer effects of ZOL and miRNA expression changes, suggesting the involvement of some miRNAs in molecular pathways mediating ZOL activity in breast cancer.

Pemetrexed has been widely used in patients with advanced non-small cell lung cancer (NSCLC). The clinical relevance of polymorphisms of folate pathway genes for pemetrexed metabolism have not been fully elucidated yet. The aim of this study was to evaluate the expression levels of circulating miR-22, miR-24, and miR-34a, possibly involved in folate pathway, in NSCLC patients treated with pemetrexed compared with healthy controls and to investigate their impact on patient clinical outcomes. A total of 22 consecutive patients with advanced NSCLC, treated with pemetrexed-based chemotherapy and 27 age and sex matched healthy controls were included in this preliminary analysis. miR-22, miR-24, and miR-34a targets were identified by TargetScan 6.2 algorithm, validating the involvement of these microRNAs in folate pathway. MicroRNAs were isolated from whole blood and extracted with miRNAeasy Mini Kit (Qiagen). miRNA profiling was performed using Real-Time PCR. SPSS 17 was used to data analysis. miR-22, miR-24, and miR-34a were found upregulated (P<0.05) in NSCLC patients versus healthy controls. Higher expression levels were recorded for miR-34a. Nevertheless, significantly higher miR-22 expression was observed in patients developing progressive disease (P=0.03). No significant associations with clinical outcome were recorded for miR-24 and miR-34a. Albeit preliminary, these data support the involvement of miR-22, miR-24, and miR-34a in advanced NSCLC. The correlation between high expression of miR-22 in whole blood and the lack of response in pemetrexed treated NSCLC patients indicates that miR-22 could represent a novel predictive biomarker for pemetrexed-based treatment.

Background: Recent findings indicate that exosomes released from cancer cells contain microRNAs (miRNAs) that may be delivered to cells of tumor microenvironment.Results: To elucidate whether miRNAs secreted from chronic myelogenous leukemia cells (CML) are shuttled into endothelial cells thus affecting their phenotype, we first analysed miRNAs content in LAMA84 exosomes. Among the 124 miRNAs identified in LAMA84 exosomes, we focused our attention on miR-126 which was found to be over-overexpressed in exosomes compared with producing parental cells. Transfection of LAMA84 with Cy3-labelled miR-126 and co-culture of leukemia cells with endothelial cells (EC) confirmed that miR-126 is shuttled into HUVECs. The treatment of HUVECs with LAMA84 exosomes for 24 hours reduced CXCL12 and VCAM1 expression, both at the mRNA and protein level, and negatively modulated LAMA84 motility and cells adhesion. Transfection in HUVECs of miR-126 inhibitor reversed the decrease of CXCL12 and restored the motility and adhesion of LAMA84 cells while the over-expression of miR-126, showed opposite effects.Conclusion: Our results show that the miR-126 shuttled by exosomes is biologically active in the target cells, and support the hypothesis that exosomal miRNAs have an important role in tumor-endothelial crosstalk occurring in the bone marrow microenvironment, potentially affecting disease progression.

The obesity hormone leptin has been implicated in breast cancer development. Breast cancer cells express the leptin receptor and are able to synthesize leptin in response to obesity‐related stimuli. Furthermore, leptin is a positive regulator of vascular endothelial growth factor (VEGF) and high levels of both proteins are associated with worse prognosis in breast cancer patients. Peroxisome proliferator‐activated receptor γ (PPARγ) ligands are therapeutic agents used in patient with Type 2 diabetes and obesity which have recently been studied for their potential anti‐tumor effect. Here, we studied if these compounds, ciglitazone and GW1929, can affect the expression of leptin and VEGF in breast cancer cells. In MDA‐MB‐231 and MCF‐7 breast cancer cells, treatment with submolar concentrations of ciglitazone and GW1929 elevated the expression of leptin and VEGF mRNA and protein, and increased cell viability and migration. These effects coincided with increased recruitment of PPARγ to the proximal leptin promoter and decreased association of a transcriptional factor Sp1 with this DNA region. J. Cell. Physiol. 228: 1368–1374, 2013. © 2012 Wiley Periodicals, Inc.

OBJECTIVE:miRNAs are attractive molecules for cancer treatment, including colon rectal cancer (CRC). We investigate on the molecular mechanism by which miR-182 could regulate thrombospondin-1 (TSP-1) expression, a protein downregulated in CRC and inversely correlated with tumor vascularity and metastasis.BACKGROUND:MicroRNAs are small non-coding RNAs that regulate the expression of different genes, involved in cancer progression, angiogenesis and metastasis. miR-182, over-expressed in colorectal cancer (CRC), has like predictive target thrombospondin-1 (TSP-1), a protein inversely correlated with tumor vascularity and metastasis that results downregulated in different types of cancer including CRC.RESULTS:We found that TSP-1 increased after transfection with anti-miR-182 and we showed that miR-182 targets TSP-1 3'UTR-mRNA in both cells. Moreover, we observed that anti-miR-182 did not induce significant variation of Egr-1 expression, but affected the nuclear translocation and its binding on tsp-1 promoter in HCT-116. Equally, Sp-1 was slightly increased as total protein, rather we found a nuclear accumulation and its loading on the TSP-1 promoter in HT-29 transfected with anti-miR-182.CONCLUSION:Our data suggest that miR-182 targets the anti-angiogenic factor TSP-1 and that anti-miR-182 determines an upregulation of TSP-1 expression in colon cancer cells. Moreover, anti-miR-182 exerts a transcriptional regulatory mechanism of tsp-1 modulating Egr-1 and Sp-1 function. Anti-miR-182 could be used to restore TSP-1 expression in order to contrast angiogenic and invasive events in CRC.

Finding new treatments targeting cancer stem cells (CSCs) within a tumor seems to be critical to halt cancer and improve patient survival. Osteosarcoma is an aggressive tumor affecting adolescents, for which there is no second‐line chemotherapy. Uncovering new molecular mechanisms underlying the development of osteosarcoma and origin of CSCs is crucial to identify new possible therapeutic strategies. Here, we aimed to characterize genetically and molecularly the human osteosarcoma 3AB‐OS CSC line, previously selected from MG63 cells and which proved to have both in vitro and in vivo features of CSCs. Classic cytogenetic studies demonstrated that 3AB‐OS cells have hypertriploid karyotype with 71–82 chromosomes. By comparing 3AB‐OS CSCs to the parental cells, array CGH, Affymetrix microarray, and TaqMan® Human MicroRNA array analyses identified 49 copy number variations (CNV), 3,512 dysregulated genes and 189 differentially expressed miRNAs. Some of the chromosomal abnormalities and mRNA/miRNA expression profiles appeared to be congruent with those reported in human osteosarcomas. Bioinformatic analyses selected 196 genes and 46 anticorrelated miRNAs involved in carcinogenesis and stemness. For the first time, a predictive network is also described for two miRNA family (let‐7/98 and miR‐29a,b,c) and their anticorrelated mRNAs (MSTN, CCND2, Lin28B, MEST, HMGA2, and GHR), which may represent new biomarkers for osteosarcoma and may pave the way for the identification of new potential therapeutic targets. J. Cell. Physiol. 228: 1189–1201, 2013. © 2012 Wiley Periodicals, Inc.

Introduction: miRNAs are noncoding RNAs that target specific mRNA with subsequent regulation of particular genes, implicated in various biological processes. In cancer, miRNAs could show a different expression from normal tissues. miRNAs have a role as oncogenes when they target tumor suppressor genes and similarly they are tumor suppressors when they target oncogenes. Areas covered: In this review, areas covered include the role of miRNAs in cancer diagnosis, prognosis and research for achievement of therapeutic strategies implicating miRNAs in oncology. As biogenesis of miRNAs is fundamental to understand their usefulness, this has also been discussed. Both miRNA expression profiles in cancer tissues and miRNA levels in peripheral blood were studied for improvement in the management of cancer patients. Expert opinion: miRNAs have the potential for better understanding of tumor biology, but could also provide clinical advancement in management and therapy of various malignancies. The possibility of miRNA detection in peripheral blood would allow an eager expansion of their application in various clinical settings for cancer. The applicability of miRNA expression profiles still needs to be defined.

Breast cancer (BC) is a heterogeneous disease that exhibits familial aggregation. Family linkage studies have identified high-penetrance genes, BRCA1 , BRCA2 , PTEN and TP53 , that are responsible for inherited BC syndromes. Moreover, a combination of family-based and population-based approaches indicated that genes involved in DNA repair, such as CHEK2 , ATM , BRIP and PALB2 , are associated with moderate risk. Therefore, all of these known genes account for only 25% of the familial aggregation cases. Recently, genome wide association studies (GWAS) in BC revealed single nucleotide polymorphisms (SNPs) in five novel genes associated to susceptibility: TNRC9 , FGFR2 , MAP3K1 , H19 and lymphocyte-specific protein 1 ( LSP1 ). The most strongly associated SNP was in intron 2 of the FGFR2 gene that is amplified and overexpressed in 5–10% of BC. rs3803662 of TNRC9 gene has been shown to be the SNP with the strongest association with BC, in particular, this polymorphism seems to be correlated with bone metastases and estrogen receptor positivity. Relevant data indicate that SNP rs889312 in MAP3K1 is correlated with BC susceptibility only in BRCA2 mutation carriers, but is not associated with an increased risk in BRCA1 carriers. Finally, different SNPs in LSP1 and H19 and in minor genes probably were associated with BC risk. New susceptibility allelic variants associated with BC risk were recently discovered including potential causative genes involved in regulation of cell cycle, apoptosis, metabolism and mitochondrial functions. In conclusion, the identification of disease susceptibility loci may lead to a better understanding of the biological mechanism for BC to improve prevention, early detection and treatment.