Effective inhibition of MYC-amplified group 3 medulloblastoma by FACT-targeted curaxin drug CBL0137

RNF126-mediated ubiquitination of FSP1 affects its subcellular localization and ferroptosis

Medulloblastoma (MB) is a prevalent malignant brain tumor among children, which can be classified into four primary molecular subgroups. Group 3 MB (G3-MB) is known to be highly aggressive and associated with a poor prognosis, necessitating the development of novel and effective therapeutic interventions. Ferroptosis, a regulated form of cell death induced by lipid peroxidation, has been identified as a natural tumor suppression mechanism in various cancers. Nevertheless, the potential role of ferroptosis in the treatment of G3-MB remains unexplored. In this study, we demonstrate that RNF126 acts as an anti-ferroptotic gene by interacting with ferroptosis suppressor protein 1 (FSP1, also known as AIFM2) and ubiquitinating FSP1 at the 4KR-2 sites. Additionally, the deletion of RNF126 reduces the subcellular localization of FSP1 in the plasma membrane, resulting in an increase in the CoQ/CoQH2 ratio in G3-MB. The RNF126-FSP1-CoQ10 pathway plays a pivotal role in suppressing phospholipid peroxidation and ferroptosis both in vivo and in vitro. Clinically, RNF126 exhibited elevated expression in G3-MB and its overexpression was significantly associated with reduced patient survival. Our findings indicate that RNF126 regulates G3-MB sensitivity to ferroptosis by ubiquitinating FSP1, which provides new evidence for the potential G3-MB therapy.

Medulloblastoma targeted therapy: From signaling pathways heterogeneity and current treatment dilemma to the recent advances in development of therapeutic strategies

Medulloblastoma (MB) is a major pediatric malignant brain tumor that arises in the cerebellum. MB tumors exhibit highly heterogeneous driven by diverse genetic alterations and could be divided into four major subgroups based on their different biological drivers and molecular features (Wnt, Sonic hedgehog (Shh), group 3, and group 4 MB). Even though the therapeutic strategies for each MB subtype integrate their pathogenesis and were developed to focus on their specific target sites, the unexpected drug non-selective cytotoxicity, low drug accumulation in the brain, and complexed MB tumor microenvironment still be huge obstacles to achieving satisfied MB therapeutic efficiency. This review discussed the current advances in modern MB therapeutic strategy development. Through the recent advances in knowledge of the origin, molecular pathogenesis of MB subtypes and their current therapeutic barriers, we particularly reviewed the current development in advanced MB therapeutic strategy committed to overcome MB treatment obstacles, focusing on novel signaling pathway targeted therapeutic agents and their combination discovery, advanced drug delivery systems design, and MB immunotherapy strategy development.

Histone chaperone SSRP1 is required for apoptosis inhibition and mitochondrial function in HCC via transcriptional promotion of TRAP1

Epigenetic regulation contributes to human health and disease, especially cancer, but the mechanisms of many epigenetic regulators remain obscure. Most research is focused on gene regulatory processes, such as mRNA translation and DNA damage repair, rather than the effects on biological functions like mitochondrial activity and oxidative phosphorylation. Here, we identified an essential role for the histone chaperone structure-specific recognition protein 1 (SSRP1) in mitochondrial oxidative respiration in hepatocellular carcinoma, and found that SSRP1 suppression led to mitochondrial damage and decreased oxidative respiration. Further, we focused on TNF receptor-associated protein 1 (TRAP1), the only member of the heat shock protein 90 (HSP90) family, which directly interacts with selected respiratory complexes and affects their stability and activity. We confirmed that SSRP1 downregulation caused a decrease in TRAP1 expression at both the mRNA and protein levels. A chromatin immunoprecipitation assay also showed that SSRP1 could deposit in the TRAP1 promoter region, indicating that SSRP1 maintains mitochondrial function and reactive oxygen species levels through TRAP1. Additionally, rescue experiments and animal experiments confirmed the mechanism of SSRP1 and TRAP1 interaction. In summary, we identified a new mechanism that connects mitochondrial respiration and apoptosis, via SSRP1.

The Neurodevelopmental and Molecular Landscape of Medulloblastoma Subgroups: Current Targets and the Potential for Combined Therapies

Medulloblastoma is the most common malignant pediatric brain tumor and is associated with significant morbidity and mortality in the pediatric population. Despite the use of multiple therapeutic approaches consisting of surgical resection, craniospinal irradiation, and multiagent chemotherapy, the prognosis of many patients with medulloblastoma remains dismal. Additionally, the high doses of radiation and the chemotherapeutic agents used are associated with significant short- and long-term complications and adverse effects, most notably neurocognitive delay. Hence, there is an urgent need for the development and clinical integration of targeted treatment regimens with greater efficacy and superior safety profiles. Since the adoption of the molecular-based classification of medulloblastoma into wingless (WNT) activated, sonic hedgehog (SHH) activated, group 3, and group 4, research efforts have been directed towards unraveling the genetic, epigenetic, transcriptomic, and proteomic profiles of each subtype. This review aims to delineate the progress that has been made in characterizing the neurodevelopmental and molecular features of each medulloblastoma subtype. It further delves into the implications that these characteristics have on the development of subgroup-specific targeted therapeutic agents. Furthermore, it highlights potential future avenues for combining multiple agents or strategies in order to obtain augmented effects and evade the development of treatment resistance in tumors.

Identification of curaxin as a potential new therapeutic for JAK2 V617F mutant patients

Myelofibrosis is a myeloproliferative neoplasm (MPN) which typically results in reduced length and quality of life due to systemic symptoms and blood count changes arising from fibrotic changes in the bone marrow. While the JAK2 inhibitor ruxolitinib provides some clinical benefit, there remains a substantial unmet need for novel targeted therapies to better modify the disease process or eradicate the cells at the heart of myelofibrosis pathology. Repurposing drugs bypasses many of the hurdles present in drug development, such as toxicity and pharmacodynamic profiling. To this end we undertook a re-analysis of our pre-existing proteomic data sets to identify perturbed biochemical pathways and their associated drugs/inhibitors to potentially target the cells driving myelofibrosis. This approach identified CBL0137 as a candidate for targeting Jak2 mutation-driven malignancies. CBL0137 is a drug derived from curaxin targeting the Facilitates Chromatin Transcription (FACT) complex. It is reported to trap the FACT complex on chromatin thereby activating p53 and inhibiting NF-kB activity. We therefore assessed the activity of CBL0137 in primary patient samples and murine models of Jak2-mutated MPN and found it preferentially targets CD34+ stem and progenitor cells from myelofibrosis patients by comparison with healthy control cells. Further we investigate its mechanism of action in primary haemopoietic progenitor cells and demonstrate its ability to reduce splenomegaly and reticulocyte number in a transgenic murine model of myeloproliferative neoplasms.

Recent progress and novel approaches to treating atypical teratoid rhabdoid tumor

Atypical teratoid rhabdoid tumors (AT/RT) are malignant central nervous system (CNS) tumors that occur mostly in young children and have historically carried a very poor prognosis. While recent clinical trial results show that this tumor is curable, outcomes are still poor compared to other central nervous system embryonal tumors. We here review prior AT/RT clinical trials and highlight promising pre-clinical results that may inform novel clinical approaches to this aggressive cancer.

The FACT-targeted drug CBL0137 enhances the effects of rituximab to inhibit B-cell non-Hodgkin's lymphoma tumor growth by promoting apoptosis and autophagy

BACKGROUND

Aggressive B-cell non-Hodgkin's lymphoma (B-NHL) patients often develop drug resistance and tumor recurrence after conventional immunochemotherapy, for which new treatments are needed.

METHODS

We investigated the antitumor effects of CBL0137. In vitro, cell proliferation was assessed by CCK-8 and colony formation assay. Flow cytometry was performed to analyze cell cycle progression, apoptosis, mitochondrial depolarization, and reactive oxygen species (ROS) production. Autophagy was detected by transmission electron microscopy and mGFP-RFP-LC3 assay, while western blotting was employed to detect proteins involved in apoptosis and autophagy. RNA-sequencing was conducted to analyze the transcription perturbation after CBL0137 treatment in B-NHL cell lines. Finally, the efficacy and safety of CBL0137, rituximab, and their combination were tested in vivo.

RESULTS

CBL0137, a small molecule anticancer agent that has significant antitumor effects in B-NHL. CBL0137 sequesters the FACT (facilitates chromatin transcription) complex from chromatin to produce cytotoxic effects in B-NHL cells. In addition, we discovered novel anticancer mechanisms of CBL0137. CBL0137 inhibited human B-NHL cell proliferation by inducing cell cycle arrest in S phase via the c-MYC/p53/p21 pathway. Furthermore, CBL0137 triggers ROS generation and induces apoptosis and autophagy in B-NHL cells through the ROS-mediated PI3K/Akt/mTOR and MAPK signaling pathways. Notably, a combination of CBL0137 and rituximab significantly suppressed B-NHL tumor growth in subcutaneous models, consistent with results at the cellular level in vitro.

CONCLUSIONS

CBL0137 has potential as a novel approach for aggressive B-NHL, and its combination with rituximab can provide new therapeutic options for patients with aggressive B-NHL. Video Abstract.

Targeting Features of Curaxin CBL0137 on Hematological Malignancies In Vitro and In Vivo

The anticancer activity of Curaxin CBL0137, a DNA-binding small molecule with chromatin remodulating effect, has been demonstrated in different cancers. Herein, a comparative evaluation of CBL0137 activity was performed in respect to acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia and multiple myeloma (MM) cultured in vitro. MTT assay showed AML and MM higher sensitivity to CBL0137's cytostatic effect comparatively to other hematological malignancy cells. Flow cytometry cell cycle analysis revealed an increase in subG1 and G2/M populations after CBL0137 cell treatment, but the prevalent type of arrest varied. Apoptosis activation by CBL0137 measured by Annexin-V/PI dual staining was more active in AML and MM cells. RT2 PCR array showed that changes caused by CBL0137 in signaling pathways involved in cancer pathogenesis were more intensive in AML and MM cells. On the murine model of AML WEHI-3, CBL0137 showed significant anticancer effects in vivo, which were evaluated by corresponding changes in spleen and liver. Thus, more pronounced anticancer effects of CBL0137 in vitro were observed in respect to AML and MM. Experiments in vivo also indicated the perspective of CBL0137 use for AML treatment. This in accordance with the frontline treatment approach in AML using epigenetic drugs.

CBL0137 impairs homologous recombination repair and sensitizes high-grade serous ovarian carcinoma to PARP inhibitors

BACKGROUND

High-grade serous ovarian carcinomas (HGSCs) are a heterogeneous subtype of epithelial ovarian cancers and include serous cancers arising in the fallopian tube and peritoneum. These cancers are now subdivided into homologous recombination repair (HR)-deficient and proficient subgroups as this classification impacts on management and prognosis. PARP inhibitors (PARPi) have shown significant clinical efficacy, particularly as maintenance therapy following response to platinum-based chemotherapy in BRCA-mutant or homologous recombination (HR)-deficient HGSCs in both the 1st and 2nd line settings. However, PARPi have limited clinical benefit in HR-proficient HGSCs which make up almost 50% of HGSC and improving outcomes in these patients is now a high priority due to the poor prognosis with ineffectiveness of the current standard of care. There are a number of potential lines of investigation including efforts in sensitizing HR-proficient tumors to PARPi. Herein, we aimed to develop a novel combination therapy by targeting SSRP1 using a small molecule inhibitor CBL0137 with PARPi in HR-proficient HGSCs.

EXPERIMENTAL DESIGN

We tested anti-cancer activity of CBL0137 monotherapy using a panel of HGSC cell lines and patient-derived tumor cells in vitro. RNA sequencing was used to map global transcriptomic changes in CBL0137-treated patient-derived HR-proficient HGSC cells. We tested efficacy of CBL0137 in combination with PARPi using HGSC cell lines and patient-derived tumor cells in vitro and in vivo.

RESULTS

We show that SSRP1 inhibition using a small molecule, CBL0137, that traps SSRP1 onto chromatin, exerts a significant anti-growth activity in vitro against HGSC cell lines and patient-derived tumor cells, and also reduces tumor burden in vivo. CBL0137 induced DNA repair deficiency via inhibition of the HR repair pathway and sensitized SSRP1-high HR-proficient HGSC cell lines and patient-derived tumor cells/xenografts to the PARPi, Olaparib in vitro and in vivo. CBL0137 also enhanced the efficacy of DNA damaging platinum-based chemotherapy in HGSC patient-derived xenografts.

CONCLUSION

Our findings strongly suggest that combination of CBL0137 and PARP inhibition represents a novel therapeutic strategy for HR-proficient HGSCs that express high levels of SSRP1 and should be investigated in the clinic.

Metabolic determinants of stemness in medulloblastoma

Medulloblastomas (MBs) are the most prevalent brain tumours in children. They are classified as grade IV, the highest in malignancy, with about 30% metastatic tumours at the time of diagnosis. Cancer stem cells (CSCs) are a small subset of tumour cells that can initiate and support tumour growth. In MB, CSCs contribute to tumour initiation, metastasis, and therapy resistance. Metabolic differences among the different MB groups have started to emerge. Sonic hedgehog tumours show enriched lipid and nucleic acid metabolism pathways, whereas Group 3 MBs upregulate glycolysis, gluconeogenesis, glutamine anabolism, and glutathione-mediated anti-oxidant pathways. Such differences impact the clinical behaviour of MB tumours and can be exploited therapeutically. In this review, we summarise the existing knowledge about metabolic rewiring in MB, with a particular focus on MB-CSCs. Finally, we highlight some of the emerging metabolism-based therapeutic strategies for MB.

The histone chaperone FACT: a guardian of chromatin structure integrity

The identification of FACT as a histone chaperone enabling transcription through chromatin in vitro has strongly shaped how its roles are envisioned. However, FACT has been implicated in essentially all aspects of chromatin biology, from transcription to DNA replication, DNA repair, and chromosome segregation. In this review, we focus on recent literature describing the role and mechanisms of FACT during transcription. We highlight the prime importance of FACT in preserving chromatin integrity during transcription and challenge its role as an elongation factor. We also review evidence for FACT's role as a cell-type/gene-specificregulator of gene expression and briefly summarize current efforts at using FACT inhibition as an anti-cancerstrategy.

MYC overexpression leads to increased chromatin interactions at superenhancers and MYC binding sites

The MYC oncogene encodes for the MYC protein and is frequently dysregulated across multiple cancer cell types, making it an attractive target for cancer therapy. MYC overexpression leads to MYC binding at active enhancers, resulting in a global transcriptional amplification of active genes. Because super-enhancers are frequently dysregulated in cancer, we hypothesized that MYC preferentially invades into super-enhancers and alters the cancer genome organization. To that end, we performed ChIP-seq, RNA-seq, circular chromosome conformation capture (4C-seq), and Spike-in Quantitative Hi-C (SIQHiC) on the U2OS osteosarcoma cell line with tetracycline-inducible MYC. MYC overexpression in U2OS cells modulated histone acetylation and increased MYC binding at super-enhancers. SIQHiC analysis revealed increased global chromatin contact frequency, particularly at chromatin interactions connecting MYC binding sites at promoters and enhancers. Immunofluorescence staining showed that MYC molecules formed punctate foci at these transcriptionally active domains after MYC overexpression. These results demonstrate the accumulation of overexpressed MYC at promoter–enhancer hubs and suggest that MYC invades into enhancers through spatial proximity. At the same time, the increased protein–protein interactions may strengthen these chromatin interactions to increase chromatin contact frequency. CTCF siRNA knockdown in MYC-overexpressed U2OS cells demonstrated that removal of architectural proteins can disperse MYC and abrogate the increase in chromatin contacts. By elucidating the chromatin landscape of MYC-driven cancers, we can potentially target MYC-associated chromatin interactions for cancer therapy.

Molecular Targeted Therapies: Time for a Paradigm Shift in Medulloblastoma Treatment?

Medulloblastoma is a rare malignancy of the posterior cranial fossa. Although until now considered a single disease, according to the current WHO classification, it is a heterogeneous tumor that comprises multiple molecularly defined subgroups, with distinct gene expression profiles, pathogenetic driver alterations, clinical behaviors and age at onset. Adult medulloblastoma, in particular, is considered a rarer "orphan" entity in neuro-oncology practice because while treatments have progressively evolved for the pediatric population, no practice-changing prospective, randomized clinical trials have been performed in adults. In this scenario, the toughest challenge is to transfer the advances in cancer genomics into new molecularly targeted therapeutics, to improve the prognosis of this neoplasm and the treatment-related toxicities. Herein, we focus on the recent advances in targeted therapy of medulloblastoma based on the new and deeper knowledge of disease biology.

Relapsed Medulloblastoma in Pre-Irradiated Patients: Current Practice for Diagnostics and Treatment

Relapsed medulloblastoma (rMB) accounts for a considerable, and disproportionate amount of childhood cancer deaths. Recent advances have gone someway to characterising disease biology at relapse including second malignancies that often cannot be distinguished from relapse on imaging alone. Furthermore, there are now multiple international early-phase trials exploring drug-target matches across a range of high-risk/relapsed paediatric tumours. Despite these advances, treatment at relapse in pre-irradiated patients is typically non-curative and focuses on providing life-prolonging and symptom-modifying care that is tailored to the needs and wishes of the individual and their family. Here, we describe the current understanding of prognostic factors at disease relapse such as principal molecular group, adverse molecular biology, and timing of relapse. We provide an overview of the clinical diagnostic process including signs and symptoms, staging investigations, and molecular pathology, followed by a summary of treatment modalities and considerations. Finally, we summarise future directions to progress understanding of treatment resistance and the biological mechanisms underpinning early therapy-refractory and relapsed disease. These initiatives include development of comprehensive and collaborative molecular profiling approaches at relapse, liquid biopsies such as cerebrospinal fluid (CSF) as a biomarker of minimal residual disease (MRD), modelling strategies, and the use of primary tumour material for real-time drug screening approaches.

Subgroup-Specific Diagnostic, Prognostic, and Predictive Markers Influencing Pediatric Medulloblastoma Treatment

Medulloblastoma (MB) is the most common malignant central nervous system tumor in pediatric patients. Mainstay of therapy remains surgical resection followed by craniospinal radiation and chemotherapy, although limitations to this therapy are applied in the youngest patients. Clinically, tumors are divided into average and high-risk status on the basis of age, metastasis at diagnosis, and extent of surgical resection. However, technological advances in high-throughput screening have facilitated the analysis of large transcriptomic datasets that have been used to generate the current classification system, dividing patients into four primary subgroups, i.e., WNT (wingless), SHH (sonic hedgehog), and the non-SHH/WNT subgroups 3 and 4. Each subgroup can further be subdivided on the basis of a combination of cytogenetic and epigenetic events, some in distinct signaling pathways, that activate specific phenotypes impacting patient prognosis. Here, we delve deeper into the genetic basis for each subgroup by reviewing the extent of cytogenetic events in key genes that trigger neoplastic transformation or that exhibit oncogenic properties. Each of these discussions is further centered on how these genetic aberrations can be exploited to generate novel targeted therapeutics for each subgroup along with a discussion on challenges that are currently faced in generating said therapies. Our future hope is that through better understanding of subgroup-specific cytogenetic events, the field may improve diagnosis, prognosis, and treatment to improve overall quality of life for these patients.

MYCN directly targets NeuroD1 to promote cellular proliferation in neuroblastoma

NeuroD1 is a neuronal differentiation factor that contains a basic helix-loop-helix (bHLH) motif. Recently, NeuroD1 was found to be associated with tumorigenesis in neuroblastoma (NB), and is known to promote cell proliferation and migration in these cells. Here, we found that MYCN regulates the expression of NeuroD1 in NB cells, and that the downregulation of MYCN using short hairpin RNAs (shRNA) results in the inhibition of cellular proliferation in NB cells. Moreover, the phenotype induced by MYCN shRNA was rescued by the exogenous expression of NeuroD1. Chromatin immunoprecipitation (ChIP) assay showed that MYCN directly binds to the E-box element in the NeuroD1 promoter region. In addition, our evaluation of two clinical databases showed that there was a positive correlation between the expression of MYCN and NeuroD1 in NB patients, which supports our in vitro data. In conclusion, this study demonstrates that MYCN-regulated NeuroD1 expression is one of the important mechanisms underlying enhanced cellular proliferation induced by the increase of MYCN expression in NB, and our results provide an important therapeutic target for NB in the future.

NeuroD1 promotes tumor cell proliferation and tumorigenesis by directly activating the pentose phosphate pathway in colorectal carcinoma

Tumor metabolic reprogramming ensures that cancerous cells obtain sufficient building blocks, energy, and antioxidants to sustain rapid growth and for coping with oxidative stress. Neurogenic differentiation factor 1 (NeuroD1) is upregulated in various types of tumors; however, its involvement in tumor cell metabolic reprogramming remains unclear. In this study, we report that NeuroD1 is positively correlated with glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the pentose phosphate pathway (PPP), in colorectal cancer cells. In addition, the regulation of G6PD by NeuroD1 alters tumor cell metabolism by stimulating the PPP, leading to enhanced production of nucleotides and NADPH. These, in turn, promote DNA and lipid biosynthesis in tumor cells, while decreasing intracellular levels of reactive oxygen species. Mechanistically, we showed that NeuroD1 binds directly to the G6PD promoter to activate G6PD transcription. Consequently, tumor cell proliferation and colony formation are enhanced, leading to increased tumorigenic potential in vitro and in vivo. These findings reveal a novel function of NeuroD1 as a regulator of G6PD, whereby its oncogenic activity is linked to tumor cell metabolic reprogramming and regulation of the PPP. Furthermore, NeuroD1 represents a potential target for metabolism-based anti-tumor therapeutic strategies.

The FAcilitates Chromatin Transcription (FACT) complex: Its roles in DNA repair and implications for cancer therapy

Genomic DNA in the nucleus is wrapped around nucleosomes, a repeating unit of chromatin. The nucleosome, consisting of octamer of core histones, is a barrier for several cellular processes that require access to the naked DNA. The FAcilitates Chromatin Transcription (FACT), a histone chaperone complex, is involved in nucleosome remodeling via eviction or assembly of histones during transcription, replication, and DNA repair. Increasing evidence suggests that FACT plays an important role in multiple DNA repair pathways including transcription-coupled nucleotide excision repair (TC-NER) of UV-induced damage, DNA single- and double-strand breaks (DSBs) repair, and base excision repair (BER) of oxidized or alkylated damaged bases. Further, studies have shown overexpression of FACT in multiple types of cancer and its association with drug resistance and patients' poor prognosis. In this review, we discuss how FACT is accumulated at the damage site and what functions it performs. We describe the known mechanisms by which FACT facilitates repair of different types of DNA damage. Further, we highlight the recent advances in a class of FACT inhibitors, called curaxins, which show promise as a new adjuvant therapy to sensitize multiple types of cancer to chemotherapy and radiation.

Kidney cancer biomarkers and targets for therapeutics: survivin (BIRC5), XIAP, MCL-1, HIF1α, HIF2α, NRF2, MDM2, MDM4, p53, KRAS and AKT in renal cell carcinoma

The incidence of renal cell carcinoma (RCC) is increasing worldwide with an approximate 20% mortality rate. The challenge in RCC is the therapy-resistance. Cancer resistance to treatment employs multiple mechanisms due to cancer heterogeneity with multiple genetic and epigenetic alterations. These changes include aberrant overexpression of (1) anticancer cell death proteins (e.g., survivin/BIRC5), (2) DNA repair regulators (e.g., ERCC6) and (3) efflux pump proteins (e.g., ABCG2/BCRP); mutations and/or deregulation of key (4) oncogenes (e.g., MDM2, KRAS) and/or (5) tumor suppressor genes (e.g., TP5/p53); and (6) deregulation of redox-sensitive regulators (e.g., HIF, NRF2). Foci of tumor cells that have these genetic alterations and/or deregulation possess survival advantages and are selected for survival during treatment. We will review the significance of survivin (BIRC5), XIAP, MCL-1, HIF1α, HIF2α, NRF2, MDM2, MDM4, TP5/p53, KRAS and AKT in treatment resistance as the potential therapeutic biomarkers and/or targets in RCC in parallel with our analized RCC-relevant TCGA genetic results from each of these gene/protein molecules. We then present our data to show the anticancer drug FL118 modulation of these protein targets and RCC cell/tumor growth. Finally, we include additional data to show a promising FL118 analogue (FL496) for treating the specialized type 2 papillary RCC.

Histone chaperone FACT complex inhibitor CBL0137 interferes with DNA damage repair and enhances sensitivity of medulloblastoma to chemotherapy and radiation

Medulloblastoma (MB) is a malignant pediatric brain tumor with a poor prognosis. Post-surgical radiation and cisplatin-based chemotherapy have been a mainstay of treatment, which often leads to substantial neurocognitive impairments and morbidity, highlighting the need for a novel therapeutic target to enhance the sensitivity of MB tumors to cytotoxic therapies. We performed a comprehensive study using a cohort of 71 MB patients' samples and pediatric MB cell lines and found that MB tumors have elevated levels of nucleosome remodeling FACT (FAcilitates Chromatin Transcription) complex and DNA repair enzyme AP-endonuclease1 (APE1). FACT interacts with APE1 and facilitates recruitment and acetylation of APE1 to promote repair of radiation and cisplatin-induced DNA damage. Further, levels of FACT and acetylated APE1 both are correlate strongly with MB patients' survival. Targeting FACT complex with CBL0137 inhibits DNA repair and alters expression of a subset of genes, and significantly improves the potency of cisplatin and radiation in vitro and in MB xenograft. Notably, combination of CBL0137 and cisplatin significantly suppressed MB tumor growth in an intracranial orthotopic xenograft model. We conclude that FACT complex promotes chemo-radiation resistance in MB, and FACT inhibitor CBL0137 can be used as a chemo-radiation sensitizer to augment treatment efficacy and reduce therapy-related toxicity in high-risk pediatric patients.

Exploring the Interaction of Curaxin CBL0137 with G-Quadruplex DNA Oligomers

Curaxins and especially the second-generation derivative curaxin CBL0137 have important antitumor activities in multiple cancers such as glioblastoma, melanoma and others. Although most of the authors suggest that their mechanism of action comes from the activation of p53 and inactivation of NF-kB by targeting FACT, there is evidence supporting the involvement of DNA binding in their antitumor activity. In this work, the DNA binding properties of curaxin CBL0137 with model quadruplex DNA oligomers were studied by ¹H NMR, CD, fluorescence and molecular modeling. We provided molecular details of the interaction of curaxin with two G-quadruplex structures, the single repeat of human telomere d(TTAGGGT)₄ and the c-myc promoter Pu22 sequence. We also performed ¹H and ³¹P NMR experiments were also performed in order to investigate the interaction with duplex DNA models. Our data support the hypothesis that the interaction of curaxin with G-quadruplex may provide a novel insight into the DNA-binding properties of CBL0137, and it will be helpful for the design of novel selective DNA-targeting curaxin analogues.

Medulloblastoma drugs in development: Current leads, trials and drawbacks

Medulloblastoma (MB) is the most common malignant brain tumor in children. Current treatment for MB includes surgical resection, radiotherapy and chemotherapy. Despite significant progress in its management, a portion of children relapse and tumor recurrence carries a poor prognosis. Based on their molecular and clinical characteristics, MB patients are clinically classified into four groups: Wnt, Hh, Group 3, and Group 4. With our increased understanding of relevant molecular pathways disrupted in MB, the development of targeted therapies for MB has also increased. Targeted drugs have shown unique privileges over traditional cytotoxic therapies in balancing efficacy and toxicity, with many of them approved and widely used clinically. The aim of this review is to present the recent progress on targeted chemotherapies for the treatment of all classes of MB.