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Neuroblastoma (NB) is the most common and aggressive pediatric cancer, characterized by a remarkable phenotypic diversity and high malignancy. The heterogeneous clinical behavior, ranging from spontaneous remission to fatal metastatic disease, is attributable to NB biology and genetics. Despite major advances in therapies, NB is still associated with a high morbidity and mortality. Thus, novel diagnostic, prognostic, and therapeutic approaches are required, mainly to improve treatment outcomes of high-risk NB patients. Among neuroepithelial cancers, NB is the most studied tumor as far as PPAR ligands are concerned. PPAR ligands are endowed with antitumoral effects, mainly acting on cancer stem cells, and constitute a possible add-on therapy to antiblastic drugs, in particular for NB with unfavourable prognosis. While discussing clinical background, this review will provide a synopsis of the major studies about PPAR expression in NB, focusing on the potential beneficial effects of hypoglycemic drugs, thiazolidinediones and metformin, to reduce the occurrence of relapses as well as tumor regrowth in NB patients.

Background Rhabdomyosarcoma (RMS) is a pediatric soft tissue sarcoma arising from myogenic precursors that have lost their capability to differentiate into skeletal muscle. The polycomb-group protein EZH2 is a Lys27 histone H3 methyltransferase that regulates the balance between cell proliferation and differentiation by epigenetically silencing muscle-specific genes. EZH2 is often over-expressed in several human cancers acting as an oncogene. We previously reported that EZH2 inhibition induces cell cycle arrest followed by myogenic differentiation of RMS cells of the embryonal subtype (eRMS). MiR-101 is a microRNA involved in a negative feedback circuit with EZH2 in different normal and tumor tissues. To that, miR-101 can behave as a tumor suppressor in several cancers by repressing EZH2 expression. We, therefore, evaluated whether miR-101 is de-regulated in eRMS and investigated its interplaying with EZH2 as well as its role in the in vitro tumorigenic potential of these tumor cells. Results Herein, we report that miR-101 is down-regulated in eRMS patients and in tumor cell lines compared to their controls showing an inverse pattern of expression with EZH2. We also show that miR-101 is up-regulated in eRMS cells following both genetic and pharmacological inhibition of EZH2. In turn, miR-101 forced expression reduces EZH2 levels as well as restrains the migratory potential of eRMS cells and impairs their clonogenic and anchorage-independent growth capabilities. Finally, EZH2 recruitment to regulatory region of miR-101-2 gene decreases in EZH2-silenced eRMS cells. This phenomenon is associated to reduced H3K27me3 levels at the same regulatory locus, indicating that EZH2 directly targets miR-101 for repression in eRMS cells. Conclusions Altogether, our data show that, in human eRMS, miR-101 is involved in a negative feedback loop with EZH2, whose targeting has been previously shown to halt eRMS tumorigenicity. They also demonstrate that the re-induction of miR-101 hampers the tumor features of eRMS cells. In this scenario, epigenetic dysregulations confirm their crucial role in the pathogenesis of this soft tissue sarcoma. Electronic supplementary material The online version of this article (doi:10.1186/s13148-015-0107-z) contains supplementary material, which is available to authorized users.

Signal-specific recruitment of EZH2 onto the miR-101-2 promoter in JR1 cells after EZH2 down-regulation. (A) ChIP assays on JR1 cells 72Â h after EZH2 or CTR siRNA transfection showing the recruitment of EZH2 and the levels of histone H3 trimethylation on Lys27 (H3K27me3) on miR-101-2, MCK, and SMAD6 (as negative control) regulatory regions. Normal rabbit IgG were used as negative control. Graphs represent the percent of immunoprecipitated material relative to input DNA. (B) mRNA levels (RT-qPCR) of pri-miR-101-2 in JR1 cells 48Â h after EZH2 siRNA treatment were normalized to GAPDH levels and expressed as fold increase over CTR siRNA.

miR-101 over-expression reduces EZH2 levels, cell proliferation, anchorage-independent growth, and cell proliferation in RD18 cells. qRT-PCR analysis of mature miR-101 (A) and EZH2 (B) 72 h post infection with pS-pre-miR-101 or control pS- retrovirus. Data were normalized using snoU6 and GAPDH levels respectively and expressed as fold increase over control (pS-, 1 arbitrary unit). Columns, means; bars, SD. Results from three independent experiments are shown. *P

Infection efficiency in eRMS cells. Representative cytofluorometric plots show the level of GFP fluorescence in RD, JR1, and RD18 cells infected with pS-pre-miR-101 or control pS- retrovirus for 72Â h, and the percentage of GFP positivity is reported inside the plots within the right upper quadrant Q2 and in the tables on the right.

EZH2 levels in eRMS cells after EZH2 down-regulation. Western blot showing the reduction of EZH2 levels in RD cells after 48 h of transfection with EZH2 pool siRNA(*) or a non-targeting control (CTR) siRNA (A), RD, JR1, and RD18 after 48 h of transfection with EZH2 5′UTR EZH2 siRNA or a non-targeting control (CTR) siRNA (B), or DZNep treatment (5 μM) or vehicle (i.e., water, referred as untreated condition: UN) (C). Total α-tubulin or GAPDH were used as loading controls. Representative of three independent experiments.

Clinical and histopathologic data of rhabdomyosarcoma tumor.

RT-qPCR analysis of N-Myc in RD cells after miR-101 over-expression or EZH2 inhibition. (A) RT-qPCR analysis of N-Myc in RD cells infected with pS-pre-miR-101 and control pS- retrovirus. Data were normalized to GAPDH levels and expressed as fold increase over control (pS-, 1 arbitrary unit). (B) RD cells were treated with DZNep (5 μM) or vehicle (i.e., water, referred as untreated condition: UN). Data were normalized to GAPDH levels and expressed as fold increase over UN (1 arbitrary unit). Columns, means; bars, SD. Results from three independent experiments are shown. *P

Scopo: L’obiettivo del presente programma di studio è stato quello di identificare e validare nuovi possibili bersagli terapeutici per l’osteosarcoma (OS) partendo dall’analisi del chinoma umano. Risultati: L’analisi del profilo di espressione genica ottenuta su 21 campioni clinici di OS ad alto grado di malignità ha permesso di selezionare le seguenti chinasi di possibile rilevanza biologica per l’OS: AURK-A, AURK-B, CDK2, PIK3CA, PLK-1. Le chinasi selezionate sono state validate tramite RNA interference. Successivamente è stata valutata l’efficacia dei relativi inibitori specifici: VX-680 e ZM-447439 inibitori delle Aurora-chinasi, Roscovitina di CDK2 e NMS1 di PLK-1, già inclusi in studi clinici. In termini d’inibizione della crescita cellulare le linee sono risultate maggiomente sensibili ai farmaci VX-680 e NMS1. E’ stata osservata una minor sensibilità ai farmaci VX-680, ZM447439 e NMS1 nelle linee doxorubicina(DX)-resistenti (caratterizzate da elevati livelli di espressione di ABCB1), indicando questi farmaci come potenziali substrati di ABCB1. La Roscovitina, nonostante i valori di IC50 elevati, non sembrerebbe substrato di ABCB1. La validazione preclinica di VX-680 e ZM447439 è stata completata. La forte inibizione della crescita è causata da endoreduplicazione per mancata citodieresi con conseguente formazione di una popolazione iperploide e apoptosi. Inoltre, VX-680 inibisce la motilità e la capacità di formare colonie. Esperimenti di associazione farmacologica mostrano che VX-680 interagisce positivamente con tutti i chemioterapici convenzionali impiegati nel trattamento dell’OS. NMS-1 produce interazioni positive con la DX in linee cellulari DX-resistenti, probabilmente grazie all’effetto revertante esercitato su ABCB1. La Roscovitina produce interazioni positive con CDDP e DX nelle varianti resistenti, effetto probbilmente dovuto al ruolo di CDK2 nei meccanismi di riparo del DNA. Conclusioni: L’analisi in vitro dell’attività degli inibitori ha permesso di identificare VX-680 come nuovo farmaco di potenziale interesse clinico, soprattutto in virtù delle sue interazioni sinergiche con i chemioterapici di uso convenzionale nel trattamento dell’osteosarcoma., Background: Objective of this study was the preclinical validation of protein kinases and kinase inhibitors of possible clinical usefulness in osteosarcoma. Results: By mining genome-wide expression profiling data obtained from 21 osteosarcoma (OS) clinical samples, five protein kinases emerged as the most relevant for the osteosarcoma biology: AURK-A, AURK-B, CDK2, PIK3CA, PLK1. Theyr validation was perfomed by RNAinterference. We therefore investigated the efficacy of the following drugs: VX-680 and ZM447439 (AURKs inhibitors), the CDK2 inhibitor Roscovitine and the PLK1 inhibitor NMS-1, which have been included in clinical trials for other tumors. In terms of cell growth inhibition, VX-680 and NMS-1 proved to be the most effective among the tested drugs. A decrease of drug sensitivity was observed in doxorubicin-resistant cell lines (characterized by a high ABCB1 expression), suggesting VX-680, ZM447439 and NMS-1 as ABCB1 substrates. Roscovitine was less effective than other drugs but it did not appear to be affected by the ABC-mediated efflux mechanisms. Preclinical validation of VX-680 and ZM447439 has been completed. Cell growth inhibition was caused by occurring endoreduplication with cytokinesis failure and consequent generation of hyperploid populations. Generally, this alteration is followed by apotosis induction. VX-680 also decreased motility and soft-agar colony formation ability of human OS cells. Drug association experiments showed that VX-680 positively interacts with all drugs conventionally used in OS. NMS-1 proved a positive interaction with DX in DX-resistant cell lines, probabily due to the revertant effect of this drug on ABCB1 activity. Roscovitine produced positive interactions with CDDP and DX in resistant variants, probabily due to CDK2 role in DNA-damage repair pathway. Conclusions: These results indicate that kinases might represent new candidate therapeutic targets for OS and in vitro analysis of two inhibitors of AURK-A and AURK-B indicated in VX-680 a new promising drug of potential clinical usefulness to target these molecules.

Scopo: L’obiettivo del presente programma di studio è stato quello di identificare e validare nuovi possibili bersagli terapeutici per l’osteosarcoma (OS) partendo dall’analisi del chinoma umano. Risultati: L’analisi del profilo di espressione genica ottenuta su 21 campioni clinici di OS ad alto grado di malignità ha permesso di selezionare le seguenti chinasi di possibile rilevanza biologica per l’OS: AURK-A, AURK-B, CDK2, PIK3CA, PLK-1. Le chinasi selezionate sono state validate tramite RNA interference. Successivamente è stata valutata l’efficacia dei relativi inibitori specifici: VX-680 e ZM-447439 inibitori delle Aurora-chinasi, Roscovitina di CDK2 e NMS1 di PLK-1, già inclusi in studi clinici. In termini d’inibizione della crescita cellulare le linee sono risultate maggiomente sensibili ai farmaci VX-680 e NMS1. E’ stata osservata una minor sensibilità ai farmaci VX-680, ZM447439 e NMS1 nelle linee doxorubicina(DX)-resistenti (caratterizzate da elevati livelli di espressione di ABCB1), indicando questi farmaci come potenziali substrati di ABCB1. La Roscovitina, nonostante i valori di IC50 elevati, non sembrerebbe substrato di ABCB1. La validazione preclinica di VX-680 e ZM447439 è stata completata. La forte inibizione della crescita è causata da endoreduplicazione per mancata citodieresi con conseguente formazione di una popolazione iperploide e apoptosi. Inoltre, VX-680 inibisce la motilità e la capacità di formare colonie. Esperimenti di associazione farmacologica mostrano che VX-680 interagisce positivamente con tutti i chemioterapici convenzionali impiegati nel trattamento dell’OS. NMS-1 produce interazioni positive con la DX in linee cellulari DX-resistenti, probabilmente grazie all’effetto revertante esercitato su ABCB1. La Roscovitina produce interazioni positive con CDDP e DX nelle varianti resistenti, effetto probbilmente dovuto al ruolo di CDK2 nei meccanismi di riparo del DNA. Conclusioni: L’analisi in vitro dell’attività degli inibitori ha permesso di identificare VX-680 come nuovo farmaco di potenziale interesse clinico, soprattutto in virtù delle sue interazioni sinergiche con i chemioterapici di uso convenzionale nel trattamento dell’osteosarcoma., Background: Objective of this study was the preclinical validation of protein kinases and kinase inhibitors of possible clinical usefulness in osteosarcoma. Results: By mining genome-wide expression profiling data obtained from 21 osteosarcoma (OS) clinical samples, five protein kinases emerged as the most relevant for the osteosarcoma biology: AURK-A, AURK-B, CDK2, PIK3CA, PLK1. Theyr validation was perfomed by RNAinterference. We therefore investigated the efficacy of the following drugs: VX-680 and ZM447439 (AURKs inhibitors), the CDK2 inhibitor Roscovitine and the PLK1 inhibitor NMS-1, which have been included in clinical trials for other tumors. In terms of cell growth inhibition, VX-680 and NMS-1 proved to be the most effective among the tested drugs. A decrease of drug sensitivity was observed in doxorubicin-resistant cell lines (characterized by a high ABCB1 expression), suggesting VX-680, ZM447439 and NMS-1 as ABCB1 substrates. Roscovitine was less effective than other drugs but it did not appear to be affected by the ABC-mediated efflux mechanisms. Preclinical validation of VX-680 and ZM447439 has been completed. Cell growth inhibition was caused by occurring endoreduplication with cytokinesis failure and consequent generation of hyperploid populations. Generally, this alteration is followed by apotosis induction. VX-680 also decreased motility and soft-agar colony formation ability of human OS cells. Drug association experiments showed that VX-680 positively interacts with all drugs conventionally used in OS. NMS-1 proved a positive interaction with DX in DX-resistant cell lines, probabily due to the revertant effect of this drug on ABCB1 activity. Roscovitine produced positive interactions with CDDP and DX in resistant variants, probabily due to CDK2 role in DNA-damage repair pathway. Conclusions: These results indicate that kinases might represent new candidate therapeutic targets for OS and in vitro analysis of two inhibitors of AURK-A and AURK-B indicated in VX-680 a new promising drug of potential clinical usefulness to target these molecules.

Single-cell force spectroscopy is an emerging technique in the field of biomedicine because it has proved to be a unique tool to obtain mechanical and functional information on living cells, with force resolution up to single molecular bonds. This technique was applied to the study of the cytoskeleton organisation of neuroblastoma cells, a life-threatening cancer typically developing during childhood, and the results were interpreted on the basis of reference experiments on human embryonic kidney cell line. An intimate connection emerges among cellular state, cytoskeleton organisation and experimental outcome that can be potentially exploited towards a new method for cancer stadiation of neuroblastoma cells.