FTO diversely influences sensitivity of neuroblastoma cells to various chemotherapeutic drugs.

Chemotherapy resistance is a significant factor in treatment failure in patients with neuroblastoma (NB), and it directly affects patient prognosis. Therefore, identifying novel therapeutic targets to enhance chemosensitivity is essential to improve the cure rate and prognosis of patients with NB. In this study, we investigated the role of FTO in chemosensitivity of NB cells to various chemotherapeutic drugs. Our results showed that high FTO expression was positively correlated with increased survival probability and favorable prognostic factors in patients with NB. FTO overexpression inhibited cell proliferation, whereas FTO knockdown promoted cell proliferation in NB cells. FTO expression alteration had contrasting effects on NB cells' sensitivity to etoposide but had no significant impact on sensitivity to cisplatin. Downregulation of FTO reduced the sensitivity of NB cells to paclitaxel, whereas upregulation of FTO enhanced its sensitivity. Additionally, the sensitivities between patients with lower and higher FTO expression to various chemotherapeutic drugs or small-molecule inhibitors were different. Thus, FTO affects the sensitivities of NB cells differently depending on the different chemotherapeutic drugs and small-molecule inhibitors. This finding may guide physicians and patients choose the appropriate chemotherapeutic drugs or small-molecule inhibitors for treatment.

Novel small molecule DMAMCL induces differentiation in rhabdomyosarcoma by downregulating of DLL1.

Rhabdomyosarcoma (RMS), a mesenchymal tumor occurring in the soft tissue of children, is associated with a defect in differentiation. This study unveils a novel anti-tumor mechanism of dimethylaminomicheliolide (DMAMCL), which is a water-soluble derivative of Micheliolide. First, we demonstrate that DMAMCL inhibits RMS cell growth without obvious cell death, leading to morphological alterations, enhanced expression of muscle differentiation markers, and a shift from a malignant to a more benign metabolic phenotype. Second, we detected decreased expression of DLL1 in RMS cells after DMAMCL treatment, known as a pivotal ligand in the Notch signaling pathway. Downregulation of DLL1 inhibits RMS cell growth and induces morphological changes similar to the effects of DMAMCL. Furthermore, DMAMCL treatment or loss of DLL1 expression also inhibits RMS xenograft tumor growth and augmented the expression of differentiation markers. Surprisingly, in C2C12 cells DMAMCL treatment or DLL1 downregulation also induces cell growth inhibition and an elevation in muscle differentiation marker expression. These data indicated that DMAMCL induced RMS differentiation and DLL1 is an important factor for RMS differentiation, opening a new window for the clinical use of DMAMCL as an agent for differentiation-inducing therapy for RMS treatment.

SESN1 functions as a new tumor suppressor gene via Toll-like receptor signaling pathway in neuroblastoma.

AIMS: Neuroblastoma (NB) is the most common extracranial solid tumor in children, with a 5-year survival rate of <50% in high-risk patients. MYCN amplification is an important factor that influences the survival rate of high-risk patients. Our results indicated MYCN regulates the expression of SESN1. Therefore, this study aimed to investigate the role and mechanisms of SESN1 in NB. METHODS: siRNAs or overexpression plasmids were used to change MYCN, SESN1, or MyD88's expression. The role of SESN1 in NB cell proliferation, migration, and invasion was elucidated. Xenograft mice models were built to evaluate SESN1's effect in vivo. The correlation between SESN1 expression and clinicopathological data of patients with NB was analyzed. RNA-Seq was done to explore SESN1's downstream targets. RESULTS: SESN1 was regulated by MYCN in NB cells. Knockdown SESN1 promoted NB cell proliferation, cell migration, and cell invasion, and overexpressing SESN1 had opposite functions. Knockdown SESN1 promoted tumor growth and shortened tumor-bearing mice survival time. Low expression of SESN1 had a positive correlation with poor prognosis in patients with NB. RNA-Seq showed that Toll-like receptor (TLR) signaling pathway, and PD-L1 expression and PD-1 checkpoint pathway in cancer were potential downstream targets of SESN1. Knockdown MyD88 or TLRs inhibitor HCQ reversed the effect of knockdown SESN1 in NB cells. High expression of SESN1 was significantly associated with a higher immune score and indicated an active immune microenvironment for patients with NB. CONCLUSIONS: SESN1 functions as a new tumor suppressor gene via TLR signaling pathway in NB.

The role of glutamate and glutamine metabolism and related transporters in nerve cells.

BACKGROUND: Glutamate and glutamine are the most abundant amino acids in the blood and play a crucial role in cell survival in the nervous system. Various transporters found in cell and mitochondrial membranes, such as the solute carriers (SLCs) superfamily, are responsible for maintaining the balance of glutamate and glutamine in the synaptic cleft and within cells. This balance affects the metabolism of glutamate and glutamine as non-essential amino acids. AIMS: This review aims to provide an overview of the transporters and enzymes associated with glutamate and glutamine in neuronal cells. DISCUSSION: We delve into the function of glutamate and glutamine in the nervous system by discussing the transporters involved in the glutamate-glutamine cycle and the key enzymes responsible for their mutual conversion. Additionally, we highlight the role of glutamate and glutamine as carbon and nitrogen donors, as well as their significance as precursors for the synthesis of reduced glutathione (GSH). CONCLUSION: Glutamate and glutamine play a crucial role in the brain due to their special effects. It is essential to focus on understanding glutamate and glutamine metabolism to comprehend the physiological behavior of nerve cells and to treat nervous system disorders and cancer.

SOX4 Mediates ATRA-Induced Differentiation in Neuroblastoma Cells.

Neuroblastoma (NB), which is considered to be caused by the differentiation failure of neural crest cells, is the most common extracranial malignant solid tumor in children. The degree of tumor differentiation in patients with NB is closely correlated with the survival rate. To explore the potential targets that mediate NB cell differentiation, we analyzed four microarray datasets from GEO, and the overlapping down- or upregulated DEGs were displayed using Venn diagrams. SOX4 was one of the overlapping upregulated DEGs and was confirmed by RT-qPCR and Western blot in ATRA-treated NGP, SY5Y, and BE2 cells. To clarify whether SOX4 was the target gene regulating NB cell differentiation, the correlation between the expression of SOX4 and the survival of clinical patients was analyzed via the R2 database, SOX4 overexpression plasmids and siRNAs were generated to change the expression of SOX4, RT-qPCR and Western blot were performed to detect SOX4 expression, cell confluence or cell survival was detected by IncuCyte Zoom or CCK8 assay, immunocytochemistry staining was performed to detect cells' neurites, and a cell cycle analysis was implemented using Flow cytometry after PI staining. The results showed that the survival probabilities were positively correlated with SOX4 expression, in which overexpressing SOX4 inhibited NB cell proliferation, elongated the cells' neurite, and blocked the cell cycle in G1 phase, and that knockdown of the expression of SOX4 partially reversed the ATRA-induced inhibition of NB cell proliferation, the elongation of the cells' neurites, and the blocking of the cell cycle in the G1 phase. These indicate that SOX4 may be a target to induce NB cell differentiation.

PRMT1 is an important factor for medulloblastoma cell proliferation and survival.

Aberrant expression of protein arginine methyltransferases (PRMTs) has been implicated in a number of brain tumors, but the role of PRMT1 in medulloblastoma, the most common malignant pediatric brain tumor, remains unexplored. By examining the publicly available databases of pediatric brain tumor collection, we found that PRMT1 was predominantly expressed in medulloblastomas across all the pediatric brain tumors and that the high-level expression of PRMT1 correlated with poor survival of medulloblastoma patients. To determine the role of PRMT1 in medulloblastoma cells, we established an inducible knockdown system and demonstrated that PRMT1 depletion decreased medulloblastoma cell proliferation and induced cell apoptosis. Furthermore, the diamidine compounds, previously shown to exhibit selective PRMT1 inhibition, suppressed medulloblastoma cell viability in a dose-dependent manner. Finally, we observed induction of medulloblastoma cell apoptosis by the potent diamidine compounds at low micromolar concentrations. Together, our results suggest that PRMT1 could be an actionable therapeutic target in medulloblastoma.

Corrigendum: Downregulation of ATXN3 enhances the sensitivity to AKT inhibitors (Perifosine or MK-2206), but decreases the sensitivity to chemotherapeutic drugs (etoposide or cisplatin) in neuroblastoma cells.

[This corrects the article DOI: 10.3389/fonc.2021.686898.].

Antitumor effects of the small molecule DMAMCL in neuroblastoma via suppressing aerobic glycolysis and targeting PFKL.

BACKGROUND: Neuroblastoma (NB) is a common solid malignancy in children that is associated with a poor prognosis. Although the novel small molecular compound Dimethylaminomicheliolide (DMAMCL) has been shown to induce cell death in some tumors, little is known about its role in NB. METHODS: We examined the effect of DMAMCL on four NB cell lines (NPG, AS, KCNR, BE2). Cellular confluence, survival, apoptosis, and glycolysis were detected using Incucyte ZOOM, CCK-8 assays, Annexin V-PE/7-AAD flow cytometry, and Seahorse XFe96, respectively. Synergistic effects between agents were evaluated using CompuSyn and the effect of DMAMCL in vivo was evaluated using a xenograft mouse model. Phosphofructokinase-1, liver type (PFKL) expression was up- and down-regulated using overexpression plasmids or siRNA. RESULTS: When administered as a single agent, DMAMCL decreased cell proliferation in a time- and dose-dependent manner, increased the percentage of cells in SubG1 phase, and induced apoptosis in vitro, as well as inhibiting tumor growth and prolonging survival in tumor-bearing mice (NGP, BE2) in vivo. In addition, DMAMCL exerted synergistic effects when combined with etoposide or cisplatin in vitro and displayed increased antitumor effects when combined with etoposide in vivo compared to either agent alone. Mechanistically, DMAMCL suppressed aerobic glycolysis by decreasing glucose consumption, lactate excretion, and ATP production, as well as reducing the expression of PFKL, a key glycolysis enzyme, in vitro and in vivo. Furthermore, PFKL overexpression attenuated DMAMCL-induced cell death, whereas PFKL silencing promoted NB cell death. CONCLUSIONS: The results of this study suggest that DMAMCL exerts antitumor effects on NB both in vitro and in vivo by suppressing aerobic glycolysis and that PFKL could be a potential target of DMAMCL in NB.

Downregulation of ATXN3 Enhances the Sensitivity to AKT Inhibitors (Perifosine or MK-2206), but Decreases the Sensitivity to Chemotherapeutic Drugs (Etoposide or Cisplatin) in Neuroblastoma Cells.

BACKGROUND: Chemotherapy resistance is the major cause of failure in neuroblastoma (NB) treatment. ATXN3 has been linked to various types of cancer and neurodegenerative diseases; however, its roles in NB have not been established. The aim of our study was to explore the role of ATXN3 in the cell death induced by AKT inhibitor (perifosine or MK-2206) or chemotherapy drugs (etoposide or cisplatin) in NB cells. METHODS: The expressions of ATXN3 and BCL-2 family members were detected by Western blot. Cell survival was evaluated by CCK8, cell confluence was measured by IncuCyte, and apoptosis was detected by flow cytometry. AS and BE2 were treated with AKT inhibitors or chemotherapeutics, respectively. RESULTS: Downregulation of ATXN3 did not block, but significantly increased the perifosine/MK-2206-induced cell death. Among the BCL-2 family members, the expression of pro-apoptotic protein BIM and anti-proapoptotic protein Bcl-xl expression increased significantly when ATXN3 was down-regulated. Downregulation of BIM protected NB cells from the combination of perifosine/MK-2206 and ATXN3 downregulation. Downregulation of ATXN3 did not increase, but decrease the sensitivity of NB cells to etoposide/cisplatin, and knockdown of Bcl-xl attenuated this decrease in sensitivity. CONCLUSION: Downregulation of ATXN3 enhanced AKT inhibitors (perifosine or MK-2206) induced cell death by BIM, but decreased the cell death induced by chemotherapeutic drugs (etoposide or cisplatin) via Bcl-xl. The expression of ATXN3 may be an indicator in selecting different treatment regimen.

Downregulation of fibronectin 1 attenuates ATRA-induced inhibition of cell migration and invasion in neuroblastoma cells.

Neuroblastoma (NB) is the most common malignant extra cranial solid tumors in children. It has been well established that retinoic acid (RA) inhibits proliferation of neuroblastoma (NB) by blocking cells at G1 phase of the cell cycle. Clinically, RA has been successfully used to treat NB patients. However, the precise mechanism underlying the potent action of RA-treated NB is not fully explored. In this work, we carried out a gene expression profiling by RNA sequencing on all-trans retinoic acid (ATRA)-treated NB cells. Cancer-related pathway enrichment and subsequent protein-protein interaction (PPI) network analysis identified fibronectin 1 (FN1) as one of the central molecules in the network, which was significantly upregulated during ATRA treatment. In addition, we found that although downregulation of FN1 had no significant effects on either cell proliferation or cell cycle distributions in the presence or absence of ATRA, it increased cell migration and invasion in NB cells and partially blocked ATRA-induced inhibition of cell migration and invasion in SY5Y NB cells. Consistent with this finding, FN1 expression levels in NB patients positively correlate with their overall survivals. Taken together, our data suggest that FN1 is a potential target for effective ATRA treatment on NB patients, likely by facilitating ATRA-induced inhibition of cell migration and invasion.

Prognostic Value of Pretreated Blood Inflammatory Markers in Patients with Bone Sarcoma: A Meta-Analysis.

METHOD: We conducted a detailed literature search in Medline and Embase databases and collected relevant publications written in English before April 2020. Overall survival (OS) and disease-free survival (DFS) were the primary and secondary outcomes, respectively. Basic features of patients, hazard ratios (HRs), and 95% confidence intervals (CI) were retrieved to assess the correlation between pretreated blood inflammatory markers and patients with bone sarcoma. This meta-analysis used Stata 12.0. RESULTS: A total of 10 studies containing 1845 cases were included for analysis. Nine of them evaluated the neutrophil lymphocyte ratio (NLR), 7 the platelet lymphocyte ratio (PLR), and 4 the lymphocyte monocyte ratio (LMR). Pooled results revealed that higher pretreatment NLR was associated with poorer OS (HR = 1.76, 95% CI: 1.29-2.41, and P < 0.001) and DFS (HR = 1.77, 95% CI: 1.09-2.88, and P = 0.021). In contrast, a lower LMR was related to worse OS (HR = 0.73, 95% CI: 0.57-0.92, and P = 0.009), but not DFS (HR = 0.68, 95% CI: 0.41-1.11, and P > 0.05). Combined results did not show a significant predictive effect of PLR on the clinical outcomes of patients with bone sarcoma (OS : HR = 1.32, 95% CI: 0.99-1.75, and P > 0.05; DFS: HR = 1.12, 95% CI: 0.87-1.44, P > 0.05). CONCLUSION: NLR and LMR might be promising predictive biomarkers for patients with bone sarcoma and could be used to stratify patients and provide personalized therapeutic strategies.

Integrated Microarray to Identify the Hub miRNAs and Constructed miRNA-mRNA Network in Neuroblastoma Via Bioinformatics Analysis.

Neuroblastomas (NB) are childhood malignant tumors originating in the sympathetic nervous system. MicroRNAs (miRNAs) play an essential regulatory role in tumorigenesis and development. In this study, NB miRNA and mRNA expression profile data in the Gene Expression Omnibus database were used to screen for differentially expressed miRNAs (DEMs) and genes (DEGs). We used the miRTarBase and miRSystem databases to predict the target genes of the DEMs, and we selected target genes that overlapped with the DEGs as candidate genes for further study. Annotations, visualization, and the DAVID database were used to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis on the candidate genes. Additionally, the protein-protein interaction (PPI) network and miRNA-mRNA regulatory network were constructed and visualized using the STRING database and Cytoscape, and the hub modules were analyzed for function and pathway enrichment using the DAVID database and BiNGO plug-in. 107 DEMs and 1139 DEGs were identified from the miRNA and mRNA chips, respectively. 4390 overlapping target genes were identified using the two databases, and 405 candidate genes which intersected with the DEGs were selected. These candidate genes were enriched in 363 GO terms and 24 KEGG pathways. By constructing a PPI network and a miRNA-mRNA regulatory network, three hub miRNAs (hsa-miR-30e-5p, hsa-miR-15a, and hsa-miR-16) were identified. The target genes of the hub miRNAs were significantly enriched in the following pathways: microRNAs in cancer, the PI3K-Akt signaling pathway, pathways in cancer, the p53 signaling pathway, and the cell cycle. In summary, our results have identified candidate genes and pathways related to the underlying molecular mechanism of NB. These findings provide a new perspective for NB research and treatment.

Analysis and identification of novel biomarkers involved in neuroblastoma via integrated bioinformatics.

Neuroblastoma (NB) is the most common extracranial solid tumor in children. Under various treatments, some patients still have a poor prognosis. Hence, it is necessary to find new valid targets for NB therapy. In this study, a comprehensive bioinformatic analysis was used to identify differentially expressed genes (DEGs) between NB and control cells, and to select hub genes associated with NB. GSE66586 and GSE78061 datasets were downloaded from the Gene Expression Omnibus (GEO) database and DEGs were selected. Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were applied to the selected DEGs. The STRING database and Cytoscape software were used to construct protein-protein interaction (PPI) networks and perform modular analysis of the DEGs. The R2 database was used for prognostic analysis. We identified a total of 238 DEGs from two microarray databases. GO enrichment analysis shows that these DEGs are mainly concentrated in the regulation of cell growth, cell migration, cell fate determination, and cell maturation. KEGG pathway analysis showed that these DEGs are mainly involved in focal adhesion, the TNF signaling pathway, cancer-related pathways, and signaling pathways regulating stem cell pluripotency. We identified the 15 most closely related DEGs from the PPI network, and performed R2 database prognostic analysis to select five hub genes - CTGF, EDN1, GATA2, LOX, and SERPINE1. This study distinguished hub genes and related signaling pathways that can potentially serve as diagnostic indicators and therapeutic biomarkers for NB, thereby improving understanding of the molecular mechanisms involved in NB.

Downregulation of PIF1, a potential new target of MYCN, induces apoptosis and inhibits cell migration in neuroblastoma cells.

Neuroblastoma (NB) is one of the most common malignant tumors in children. Chemotherapy resistance is one of the significant challenges in the treatment of high-risk NB patients, and it is necessary to search for new valid targets for NB treatment. This study aims to explore the possible role of PIF1 in NB by using bioinformatic analysis and downregulation of PIF1 with specific siRNA. Kyoto genome encyclopedia and R language based gene ontology was used to analyze the differentially expressed genes (DEGs) (including PIF1) when MYCN expression was silenced in NB cells. Analysis based on the R2 database showed a lower expression of PIF1 correlated with good prognosis in NB patients. Downregulation of MYCN expression by transfecting MYCN siRNA (#1, #2) into NB cells decreased the PIF1 expression at both mRNA and protein levels, while upregulation of MYCN expression by transfecting MYCN overexpressed plasmid increased the PIF1 expression. We further found that downregulation of PIF1 expression by transfecting PIF1 siRNA (#1, #2) into NB cells, increased the number of apoptotic cells, inhibited the cell survival, decreased the ability of cell migration and induced a cell cycle arrest at G1 phase. These data indicated that PIF1, as a potential new target of MYCN, maybe a novel target for NB treatment.

Novel agent DMAMCL suppresses osteosarcoma growth and decreases the stemness of osteosarcoma stem cell.

Osteosarcoma (OS) is the most common primary malignancy of bone that mostly affects children, adolescents, and young people. Despite advances have been made in multimodal therapy of OS, the long-term survival rate has reached a plateau, and the main obstacles are bad response to chemotherapy and gained chemoresistance. In this study, we tested the therapeutic effect of a newly reported drug, DMAMCL, on OS. Five human OS cell lines (143B, MNNG, MG63, Saos-2, U-2OS), and the mouse fibroblast cell line (NIH3T3) and human retinal epithelial cell (ARPE19) were used. The anti-tumor effect of DMAMCL was studied by MTS assay or IncuCyte-Zoom (in vitro), and Xenograft-mice-model (in vivo). Changes of cell cycle, apoptotic cells, caspase3/7 activities, and stemness after DMAMCL treatment were investigated. BAX siRNAs were used to knockdown the expression of BAX. Expressions of CyclinB1, CDC2, BCL-2 family, PARP, CD133, and Nanog were measured by Western Blotting. DMAMCL-induced dose-dependent OS cell death in vitro, and suppressed tumor growth and extended the survival of xenograft-bearing mice. DMAMCL-induced G2/M phase arrest in vitro, and apoptosis both in vitro and in vivo. Down-regulation of BAX expression attenuated the DMAMCL-induced OS cell death in vitro. We also found that DMAMCL inhibited the stemness in OS cells. These results indicated that DMAMCL possess therapeutic value in OS and may be a promising candidate for the new drug discovery for OS therapy.

PRMT1 promotes neuroblastoma cell survival through ATF5.

Aberrant expression of protein arginine methyltransferases (PRMTs) has been implicated in a number of cancers, making PRMTs potential therapeutic targets. But it remains not well understood how PRMTs impact specific oncogenic pathways. We previously identified PRMTs as important regulators of cell growth in neuroblastoma, a deadly childhood tumor of the sympathetic nervous system. Here, we demonstrate a critical role for PRMT1 in neuroblastoma cell survival. PRMT1 depletion decreased the ability of murine neuroblastoma sphere cells to grow and form spheres, and suppressed proliferation and induced apoptosis of human neuroblastoma cells. Mechanistic studies reveal the prosurvival factor, activating transcription factor 5 (ATF5) as a downstream effector of PRMT1-mediated survival signaling. Furthermore, a diamidine class of PRMT1 inhibitors exhibited anti-neuroblastoma efficacy both in vitro and in vivo. Importantly, overexpression of ATF5 rescued cell apoptosis triggered by PRMT1 inhibition genetically or pharmacologically. Taken together, our findings shed new insights into PRMT1 signaling pathway, and provide evidence for PRMT1 as an actionable therapeutic target in neuroblastoma.

Combination of Rapamycin and MK-2206 Induced Cell Death via Autophagy and Necroptosis in MYCN-Amplified Neuroblastoma Cell Lines.

Neuroblastoma (NB) is the most common pediatric malignant extracranial solid tumor. Despite multi-modality therapies, the emergence of drug resistance is an obstacle in the treatment of high-risk NB patients (with MYCN amplification). In our previous study, we found that rapamycin and MK-2206 synergistically induced cell death in MYCN-amplified cell lines but the mechanisms remained unclear. In our present study, either 3-MA or necroatatin-1 blocked the cell death induced by rapamycin and MK-2206, but z-VAD-fmk did not block this cell death. The expressions of autophagy markers (ATG5, ATG7, Beclin-1, LC3 B) and the necroptosis marker RIPK3 increased and another necroptosis marker RIPK1 decreased after the combination treatment of rapamycin and MK-2206, and were accompanied by the morphological characteristics of autophagy and necroptosis. In NB xenograft tumor tissues, the expressions of autophagy and necroptosis markers were consistent with observations in vitro. These data suggested that autophagy and necroptosis contributed to the cell death induced by rapamycin and MK-2206 in NB cells. To understand the role of MYCN in this process, MYCN expression was downregulated in MYCN-amplified cell lines (NGP, BE2) using siRNAs and was upregulated in MYCN non-amplified cell lines (AS, SY5Y) using plasmid. We found the cell death induced by rapamycin and MK-2206 was MYCN-dependent. We also found that the metabolic activity in NB cells was correlated with the expression level of MYCN. This study delineates the role of MYCN in the cell death induced by combination treatment of rapamycin and MK-2206 in MYCN-amplified NB cells.

The anti-tumor growth effect of a novel agent DMAMCL in rhabdomyosarcoma in vitro and in vivo.

BACKGROUND: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children with poor survival. New treatment approaches are urgently needed to improve treatment efficacy in RMS patients. DMAMCL is a novel agent from Asteraceae family that has been tested in phase I clinical trials in adult glioma in Australia. METHODS: Five RMS cell lines (RD, RH18, RH28, RH30 and RH41) were used. The in vitro anti-tumor effect of DMAMCL, alone or in combination with VCR or Epirubicin, was studied using MTS assay or IncuCyte-Zoom cell confluency assay, and further validated by xenograft-mouse model in vivo. Changes in caspase-3/7 activity, cell-cycle progression and generation of ROS after DMAMCL treatment were investigated. Bim mRNA expression was measured by RT-qPCR, and protein expressions of Bim and phosphorylated-NF-κB(p65) by Western blotting. Small interfering RNAs (siRNA) of Bim were used to study the role of Bim in DMAMCL-induced cell death. RESULTS: In vitro, DMAMCL treatment induced a dose-dependent increase in cell death that could be blocked by pan-caspase-inhibitor-Z-VAD-fmk in five RMS cell lines. The percent of cells in SubG1 phase and activities of caspase-3/7 increased after DMAMCL treatment; The combination of DMAMCL with VCR or Epirubicin significantly increased cell death compared to each reagent alone. In vivo, DMAMCL(75 mg/kg or 100 mg/kg) inhibited tumor growth and prolonged survival of mice bearing xenograft RMS tumors (RD, RH18, RH30, RH41). Compared to treatment with DMAMCL or VCR, a combination of two reagents caused significant inhibition of tumor growth (RD, RH41), even after treatment termination. The expression of Bim increased at protein level after DMAMCL treatment both in vitro and in vivo. The expression of p-NF-κB(p65) had a transient increase and the generation of ROS increased after DMAMCL treatment in vitro. Transfection of Bim siRNA into RMS cells blocked the DMAMCL-induced increase of Bim and partially attenuated the DMAMCL-induced cell death. CONCLUSION: DMAMCL had an anti-tumor growth effect in vitro and in vivo that potentially mediated by Bim, NF-κB pathway and ROS. A combination of DMAMCL with chemotherapeutic drugs significantly increased the treatment efficacy. Our study supports further clinical evaluation of DMAMCL in combination with conventional chemotherapy.

P53/PUMA are potential targets that mediate the protection of brain-derived neurotrophic factor (BDNF)/TrkB from etoposide-induced cell death in neuroblastoma (NB).

The over-expressions of brain-derived neurotrophic factor (BDNF) and its tyrosine kinase receptor TrkB have been reported to induce chemo-resistance in neuroblastoma (NB) cells. In this study, we investigated the roles of P53 and BCL2 family members in the protection of BDNF/TrkB from etoposide-induced NB cell death. TB3 and TB8, two tetracycline (TET)-regulated TrkB-expressing NB cell lines, were utilized. The expressions of P53 and BCL2 family members were detected by Western blot or RT-PCR. Transfection of siRNAs was used to knockdown P53 or PUMA. Activated lentiviral was used to over-express PUMA. Cell survival was performed by MTS assay, and the percentage of cell confluence was measured by IncuCyte ZOOM. Our results showed that etoposide treatment induced significant and time-dependent increase of P53, which could be blocked by pre-treatment with BDNF, and knockdown P53 by transfecting siRNA attenuated etoposide-induced TrkB-expressing NB cell death. PUMA was the most significantly changed BCL2 family member after treatment with etoposide, and pre-treatment with BDNF blocked the increased expression of PUMA. Transfection with siRNA inhibited etoposide-induced increased expression of PUMA, and attenuated etoposide-induced NB cell death. We also found that over-expression of PUMA by infection of activated lentiviral induced TrkB-expressing NB cell death in the absence of etoposide, and treatment of BDNF protected NB cells from PUMA-induced cell death. Our results suggested that P53 and PUMA may be potential targets that mediated the protection of BDNF/TrkB from etoposide-induced NB cell death.