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Collective cell migration is important for normal development and tissue homeostasis, but can also promote cancer metastasis. To migrate collectively, cells need to coordinate their protrusion formation, rear retraction, adhesion sites dynamics, as well as forces generation and transmission. Nevertheless, the regulatory mechanisms coordinating these processes remain elusive. Using the A431 carcinoma cell line, we identify the kinase MAP4K4 as a central regulator of collective migration. We show that MAP4K4 inactivation blocks the migration of clusters while its overexpression decreases cluster cohesion. MAP4K4 regulates protrusion and retraction dynamics, remodels the actomyosin cytoskeleton, and controls the stability of both cell-cell and cell substrate adhesion. MAP4K4 promotes focal adhesion disassembly through the phosphorylation of Moesin, an actin and plasma membrane cross-linker, but disassembles adherens junctions through a Moesin-independent mechanism. By analyzing traction and intercellular forces, we found that the stabilization of adhesion sites in MAP4K4 loss of function leads to a tensional disequilibrium throughout the cell cluster, increasing the traction forces exerted onto the substrate and the tension loading at the cell-cell adhesions. Together, our results indicates that MAP4K4 activity is a key regulator of biomechanical forces at adhesion sites, promoting collective migration.

We evaluated the potential effects of ATO in different pediatric SHH-MB cell lines (ONS-76: TP53-wild type; DAOY and UW402: TP53-mutated). MB cell lines molecular subgroup was confirmed and TP53 mutations were validated. Cell viability, clonogenicity and apoptosis were evaluated after ATO treatment at different concentrations (1–16 µM) alone or combined with irradiation doses (0.5, 1, 2 and 4 Gy). Rad51 and Ku86 proteins were evaluated by WB. ATO treatment reduced cell viability for all SHH-MB cell lines. Significant decrease of clonogenic capacity and higher apoptosis rates were also observed after ATO exposure, being cell death more pronounced (>70%) for the SHH-MB TP53-mutated. Combined treatment of ATO with irradiation also reduced colonies formation in UW402 tumor cells, which was independent of DNA damage repair proteins Rad51 and Ku86. In silico analyses suggested that a set of genes from cell cycle and p53 pathways are differentially expressed in SHH tumor subtypes, suggesting that cell lines may respond to therapies according to the gene expression profiles. Herein, we showed ATO cytotoxicity in pediatric SHH cell lines, with marked radiosensitizing effect for the MB-SHH TP53-mutated cells. These results highlight the potential of ATO, alone or in combination with radiotherapy, supporting further clinical investigations.

Collective cell migration is involved in development, wound healing and metastasis. In the Drosophila ovary, border cells (BC) form a small cluster that migrates collectively through the egg chamber. To achieve directed motility, the BC cluster coordinates the formation of protrusions in its leader cell and contractility at the rear. Restricting protrusions to leader cells requires the actin and plasma membrane linker Moesin. Herein, we show that the Ste20-like kinase Misshapen phosphorylates Moesin in vitro and in BC. Depletion of Misshapen disrupts protrusion restriction, thereby allowing other cells within the cluster to protrude. In addition, we show that Misshapen is critical to generate contractile forces both at the rear of the cluster and at the base of protrusions. Together, our results indicate that Misshapen is a key regulator of BC migration as it coordinates two independent pathways that restrict protrusion formation to the leader cells and induces contractile forces., Directed motility of cell clusters requires coordination of protrusion formation at the front of leader cells and contractility at the rear. Here the authors show that the kinase Misshapen restricts protrusions to the leader cell and promotes contractile forces at the rear of the cluster.

Progresses in multimodal treatments have significantly improved the outcomes for childhood cancer. Nonetheless, for about one-third of patients with Ewing sarcoma, rhabdomyosarcoma, or osteosarcoma steady remission has remained intangible. Thus, new biomarkers to improve early diagnosis and the development of precision-targeted medicine remain imperative. Over the last decade, remarkable progress has been made in the basic understanding of miRNAs function and in interpreting the contribution of their dysregulation to cancer development and progression. On this basis, this review focuses on what has been learned about the pivotal roles of miRNAs in the regulation of key genes implicated in childhood sarcomas.

Background Overall survival of Ewing sarcoma (EWS) remains poor and less than 30% of patients with metastatic or recurrent disease survive despite current treatments. Thus, there is a constant search for new biomarkers for diagnosis, prognosis and prediction of therapy. Numerous studies have reported the abnormal expression of miR-708-5p in tumors of different origins. However, its role in EWS remains unclear. Procedure qRT-PCR was performed in nineteen consecutive EWS samples and twelve non-tumor bone samples from age-matched controls. Functional assays were performed in SK-ES-1 cells transfected with miR-708 lentiviral-based vectors and results analyzed in terms of clonogenicity, migration, invasion and western blot. Results We show that miR-708-5p is downregulated in EWS tissues though no associations with any prognostic features such as HUVOS grade, event or survival were found in our cohort. Nonetheless, expression levels of this micro-RNA were inversely associated with the presence of the EWS/FLI1 translocation. When miR-708-5p was transfected into the SK-ES-1 cell line, it did not affect migration or clonogenicity, but promoted a significant increase on the invasive potential of cells endorsed with high expression of MMP2. Conclusions Taken together, our results suggest that despite downregulated in EWS samples, this miRNA might represent a secondary genetic alteration derived from the pleiotropic cellular effects of the abnormal EWS/FLI1 transcription factor that does not affect tumor growth but instead, is related with the promotion of tumor invasion, not being suitable for future therapeutic intervention.

Over the last decade, the rho-associated kinases and several metastasis-associated microRNAs have emerged as important contributors of tumor invasion. However, despite prominence, our understanding of their involvement in the metastatic potential of Ewing Sarcoma (EWS) is incomplete. The expression profiles of ROCK1 or ROCK2 and miR-124-3p, miR-138-5p, miR-139-5p, miR-335-5p and miR-584-5p (all of which were previously predicted or validated to regulate these kinases) were evaluated through qRT-PCR and associated with clinical parameters. In vitro assays to evaluate colony formation and invasion/migration capacieties were performed on SK-ES-1 cells transfected with pre-miR mimics. ROCK1 expression was significantly reduced in EWS tissues, though there was no association with pathological parameters. miR-124-3p, miR-139-5p and miR-335-3p were also found significantly downregulated and positively correlated with ROCK1. Stratification indicated an association between lower levels of miR-139-5p and miR-584-5p with disease progression (p

Epithelial to Mesenchymal Transition (EMT) is a normal cellular process that is also triggered during cancer progression and metastasis. EMT induces cellular and microenviromental changes, resulting in loss of epithelial features and acquisition of mesenchymal phenotypes. The growth factor TGFβ and the transcription factor SNAIL1 (SNAIL) have been described as inducers of EMT. Here, we carried out an EMT model with non-tumorigenic cell line MCF-10A induced with the TGFβ2 specific isoform of TGF protein family. The model was validated by molecular, morphological and functional experiments and showed correlation with the up-regulation of SNAIL. In order to identify additional regulators of EMT in this non-tumorigenic model, we explored quantitative proteomics, which revealed the Ubiquitin carboxyl-terminal hydrolase 47 (USP47) as one of the top up-regulated proteins. USP47 has a known role in cell growth and genome integrity, but not previously correlated to EMT. After validating USP47 alterations using MRM and antibody-based assays, we demonstrated that the chemical inhibition of USP47 with the inhibitor P5091 reduced expression of EMT markers and reverted morphological changes in MCF-10A cells undergoing EMT. These results support the involvement of USP47 in our EMT model as well as potential applications of deubiquitinases as therapeutic targets for cancer progression management. Biological significance Metastasis is responsible for most cancer-associated mortality. Additionally, metastasis requires special attention, as the cellular transformations make treatment at this stage very difficult or occasionally impossible. Early steps in cancer metastasis involve the ability to detach from the solid tumor mass and invade the surrounding stromal tissues through cohesive migration, or a mesenchymal or amoeboid invasion. One of the first steps for metastatic cascade is denominated epithelial to mesenchymal transition (EMT), which can be triggered by different factors. Here, our efforts were directed to better understand this process and identify new pathways that contributes for acquisition of EMT, mainly focused on post translational modifications related to ubiquitin proteasome system. Our model of EMT induction by TGFβ2 mimics early stage of metastatic cancer in epithelial breast cells and a proteomic study carried out for such model demonstrates that the deubiquitinase enzyme USP47 acts in SNAIL stabilization, one of the most important transcription factors for EMT phenotype acquisition and consequent metastasis. In addition, the inhibiton of USP47 with P5091, reverted the EMT phenotype. Together the knowledge of such processes of cancer progression and regulation can help in designing new strategies for combined therapies for control of cancer in early stages.

The Protein Inhibitor of Activated STAT 1 (PIAS1) is an E3 SUMO ligase that plays important roles in various cellular pathways, including STAT signaling, p53 pathway, and the steroid hormone signaling pathway. PIAS1 can SUMOylate PML (at Lys-65 and Lys-160) and PML-RARα promoting their ubiquitin-mediated degradation. Increasing evidence shows that PIAS1 is overexpressed in various human malignancies, including prostate and lung cancers. To understand the mechanism of action of PIAS1, we developed a quantitative SUMO proteomic approach to identify potential substrates of PIAS1 in a system-wide manner. Our analyses enabled the profiling of 983 SUMO sites on 544 proteins, of which 204 SUMO sites on 123 proteins were identified as putative PIAS1 substrates. These substrates are involved in different cellular processes, such as transcriptional regulation, DNA binding and cytoskeleton dynamics. Further functional studies on Vimentin (VIM), a type III intermediate filament protein involved in cytoskeleton organization and cell motility, revealed that PIAS1 exerts its effects on cell migration and cell invasion through the SUMOylation of VIM at Lys-439 and Lys-445 residues. VIM SUMOylation was necessary for its dynamic disassembly, and cells expressing a non-SUMOylatable VIM mutant showed reduced levels of proliferation and migration. Our approach not only provides a novel strategy for the identification of E3 SUMO ligase substrates, but also yields valuable biological insights into the unsuspected role of PIAS1 and VIM SUMOylation on cell motility.

Osteossarcoma (OS) é uma neoplasia que acomete principalmente as metáfises de ossos longos, sendo o tumor ósseo pediátrico mais comum. O tratamento consiste em ressecção cirúrgica, tratamento quimioterápico multimodal neo-adjuvante e adjuvante. No entanto, apesar dos tratamentos, cerca de 80% dos pacientes que apresentam metástase tem uma sobrevida curta. Deste modo, torna-se necessário um melhor entendimento do processo metastático, assim como da busca por novos alvos terapêuticos. Uma das principais vias relacionada à invasão e migração das células neoplásicas é a das GTPases Rho, cujas principais moléculas efetoras são as quinases ROCK1 e 2, responsáveis por mediar a migração através do controle do citoesqueleto. Tais quinases têm sido relatadas hiperexpressas em diversas neoplasias e associadas ao pior prognóstico. Recentemente, pesquisas também têm apontado a desregulação de miRNAs na tumorigênese, sendo que a hipoexpressão de alguns microRNAs estão relacionados à hiperexpressão das ROCKs e, portanto, envolvidos no processo metastático. No presente trabalho, estudou-se a expressão tanto das ROCKs quanto de miRNAs associados a elas em amostras tumorais de OS por meio de PCR em tempo real. Encontramos uma hipoexpressão de ROCK1 nas amostras OS quando comparadas ao osso não neoplásico controle, enquanto que ROCK2 não apresentou diferença. O miR-138 foi encontrado hiperexpresso e obteve correlação com ROCK2, além de associação com a sobrevida. Os miR-139 e miR-708 demonstraram-se hipoexpressos nas amostras tumorais. Já os miR-196b e miR-584 não apresentaram diferenças. Após as análises de expressão, optou-se pelo estudo do miR-708 em linhagens de OS, desta forma, sua expressão foi induzida em três linhagens celulares, através de um vetor lentiviral, e foram realizados ensaios funcionais com o objetivo de estabelecer o papel deste miRNA. Não foi observada diferença nas taxas de proliferação ou capacidade clonogênica quando a expressão do miR-708 foi indizida. No ensaio de migração wound healing o miR-708 reduziu a migração da linhagem SAOS-2, enquanto que no ensaio de invasão induziu a invasão da linhagem MG-63 em matrigel, mas reduziu esse potencial nas linhagens HOS e SAOS-2 na matriz de gelatina. Uma análise in silico dos alvos deste miRNA apontou sua associação às vias WNT, MAPK e de Junções Aderentes. Desta forma, sugere-se que o miR-708 pode estar envolvido no controle processos que levam ao desenvolvimento de metástase, principalmente na interação com a matriz extracelular. Osteosarcoma (OS) is a neoplasia that mainly occurs at the metaphyses of long bones, being the most common pediatric bone tumor. The treatment is based on surgical resection and the multimodal chemoterapy adjuvant and neoadjuvant. However, despite the treatment, around 80% of patients who evolve to metastais present a poor survival. Therefore, understanding the metastatic process is essencial, as well as the search for new therapy targets. The mainly pathway related to invasion and migration in neoplasic cells is regulated by the Rho GTPases, and their main effectors are the kinases ROCK1 and ROCK2, which are responsible for cytoskeleton control. The hyperexpression of these kinases has been described in different cancers and it has been associated to poor prognostic. In parallel, several studies have extensively demonstrated miRNA deregulation in tumorigenesis, and the hipoexpression of some miRNA are related to ROCK upregulation, consequently, involved with metastasis. Herein, we studied the expression profiles of ROCK1 and 2 and associated miRNAs in OS tumor samples by means of qRT-PCR. We found downregulation of ROCK1 in OS samples when compared to normal bone (control), while ROCK2 did not show differences. MiR-138 showed hiperexpression and was correlated with ROCK2, and an association with survival rates. MiR-139 and miR-708 were found downregulated in tumor samples, though miR- 196b and miR-584 did not show differences in expression. Afterwards, miR-708 expression was induced in three OS cell lines, aiming establish miR-708 role. Proliferation and clonogenic essays did not present any effects when miR-708 was induced. In the wound healing essay, miR-708 reduced the migration of SAOS-2 cells, and in invasion essay, miR-708 induced invasion of MG-63 cells in a matrigel matrix, while reduced the invasive potential of HOS and SAOS-2 cell lines in a gelatin matrix. An in silico analysis of miR-708 targets highlighted its association with WNT, MAPK and Adherent Junction pathways. Therefore, we suggest that miR-708 can be involved in process that leads to metastasis, mainly related to extracellular matrix interation.

Osteosarcoma (OS) is the most common primary malignant bone tumor with two peaks of incidence, in early adolescence and the elderly. Patients affected with this malignancy often present metastatic disease at diagnosis, and despite multimodality therapy, survival has not improved substantially over the past 3 decades. Recently, miR-138-5p, proposed as a crucial intracellular mediator of invasion, has been recognized to target the Rho-associated coiled-coil containing protein kinase 2 (ROCK2). Dysregulation of ROCK1 and ROCK2 was also described in OS, being associated to higher metastasis incidence and worse prognosis. Nonetheless, the specific roles of miR-138-5p in pediatric and young adult OS and its ability to modulate these kinases remain to be established. Thus, in the present study, the expression levels miR-138-5p were evaluated in a consecutive cohort of exclusively pediatric and young adult primary OS samples. In contrast to previous reports that included adult tissues, our results showed upregulation of miR-138-5p associated with reduced event-free survival and relapsed cases. In parallel, ROCK1 mRNA levels were significantly reduced in tumor samples and negatively correlated with miR-138-5p. Similar correlations were observed after studying the profiles of ROCK1 and ROCK2 by immunohistochemistry. Our data present miR-138-5p as a consistent prognostic factor in pediatric and young adult OS, reinforcing its participation in the post-transcriptional regulation of ROCK kinases.

miRNAs have been identified as key regulators of almost all cellular processes, therefore, their dysregulation is involved with several diseases, including cancer. miRNAs specifically related to the metastastic cascade are called metastamiRs and can be involved with different steps of this process, including loss of adhesion. Osteosarcoma (OS) is the most common primary malignant pediatric bone tumor that often presents metastatic disease at diagnosis; therefore, a deeper study of adhesion-associated miRNAs could shed light on its pathophysiology. Online databases were used to select four miRNAs (miR-139; miR-181b; miR-584; miR-708) predicted or validated to target proteins related to adherent junctions and focal adhesion pathways, and their expression levels and possible associations with clinical features evaluated in primary OS samples. Our results showed downregulation of miR-139-5p and miR-708-5p in OS samples compared to non-neoplastic controls. Moreover, lower expression of miR-708-5p was associated with poor overall survival and higher expression of miR-181b-5p related to worst chemotherapy response (low HUVOS level). Based on these results, we selected miR-139-5p and miR-708-5p for further functional testing. Inducing the expression of miR-139-5p diminished the clonogenic capacity of the HOS cell line, while upregulation of miR-708-5p was related to a lower cellular adhesion. In summary, this work identified new signatures of microRNA dysregulation that may serve as useful prognostic markers in this aggressive pediatric bone tumor.

Medulloblastoma (MB) treatment is continuously evolving. Better treatment approaches, focused on particular molecular pathways involved in MB development and progression support new treatment strategies. This article explores the antiproliferative, proapoptotic and radiosensitizing effects of Methoxyamine (MX), a base excision repair (BER) inhibitor that has shown anticancer potential by sensitizing tumor cells to ionizing radiation and chemotherapy. The DAOY (a desmoplastic cerebellar-derived MB) and ONS-76 (classical MB) cell lines were treated with MX at different concentrations, either alone or combined with various chemotherapeutic compounds: cisplatin (CDDP), temozolomide (TMZ) and thiotepa (THIO). Additionally, cell lines were exposed to MX and treated at different ionizing radiation fractions. Measurement of cell growth by XTT assay, clonogenic assay and detection of apoptotic cell death through caspase activity was obtained. Exposure to MX significantly decreased cell proliferation (p

Despite advances in neurosurgery and aggressive treatment with temozolomide (TMZ) and radiation, the overall survival of patients with glioblastoma (GBM) remains poor. Vast evidence has indicated that the nuclear factor NF-κB is constitutively activated in cancer cells, playing key roles in growth and survival. Recently, Dehydroxymethylepoxyquinomicin (DHMEQ) has shown to be a selective NF-κB inhibitor with antiproliferative properties in GBM. In the present study, the ability of DHMEQ to surmount tumor's invasive nature and therapy resistance were further explored. Corroborating results showed that DHMEQ impaired cell growth in dose- and time-dependent manners with G2/M arrest when compared with control. Clonogenicity was also significantly diminished with increased apoptosis, though necrotic cell death was also observed at comparable levels. Notably, migration and invasion were inhibited accordingly with lowered expression of invasion-related genes. Moreover, concurrent combination with TMZ synergistically inhibited cell growth in all cell lines, as determined by proliferation and caspase-3 activation assays, though in those that express O6-methylguanine-DNA methyltransferase, the synergistic effects were schedule dependent. Pretreatment with DHMEQ equally sensitized cells to ionizing radiation. Taken together, our results strengthen the potential usefulness of DHMEQ in future therapeutic strategies for tumors that do not respond to conventional approaches.