FBW7 in hematological tumors

TCEB3 initiates ovarian cancer apoptosis by mediating ubiquitination and degradation of MCL-1

Platinum resistance remains a major contributor to the poor prognosis of ovarian cancer. Anti-apoptotic protein myeloid cell leukemia-1 (MCL-1) has emerged as a promising target for overcoming drug resistance, but different cancer cells utilize distinct protein degradation pathways to alter MCL-1 level. We systematically investigated E3 ligases to identify novel candidates that mediate platinum resistance in ovarian cancer. Transcription Elongation Factor B (TCEB3) has been identified as a novel E3 ligase recognition subunit that targets MCL-1 in the cytoplasm during platinum treatment other than its traditional function of targeting the Pol II in the nuclear compartment. TCEB3 expression is downregulated in platinum-resistant cell lines and this low expression is associated with poor prognosis. The ubiquitination of MCL-1 induced by TCEB3 leads to cell death in ovarian cancer. Moreover, platinum treatment increased the cytoplasm proportion of TCEB3, and the cytoplasm localization of TCEB3 is important for its targeting of MCL-1. This study emphasizes the dual function of TCEB3 in homeostasis maintenance and in cell fate determination under different conditions, and provides a new insight into drug resistance in ovarian cancer.

Deciphering the spectrum of cutaneous lymphomas expressing TFH markers

T-follicular helper (TFH) markers are expressed in the microenvironnement of marginal zone B-cell lymphoma (MZL), and in lymphomas arising from TFH-cells, sometimes making the differential diagnosis difficult. In the skin, the "TFH-spectrum" is poorly defined, going from primary cutaneous lymphoproliferative disorder with small/medium CD4+ T-cells (SMLPD) to cutaneous localizations of systemic angioimmunoblastic T-cell lymphoma (cAITL), and may pass through intermediate forms (primary cutaneous T-follicular helper derived lymphoma, not otherwise specified (PCTFHL,NOS)). We retrospectively analyzed 20 MZL, 13 SMLPD, 5 PCTFHL, and 11 cAITL clinically, histologically, and molecularly, to define tools to differentiate them. Characteristics that might favor the diagnosis of MZL over SMLPD are: multiple skin nodules (p < 0.001), nodular architecture (p < 0.01), residual germinal centers with follicular dendritic cell network (p < 0.001), monotypic plasma cells (p < 0.001), and few staining with PD1 (p = 0.016) or CXCL13 (p = 0.03). PCTFHL and cAITL presented as multiple (p < 0.01) lesions, in older patients (p < 0.01), with systemic symptoms and/or biological alterations (p < 0.01). Immunophenotypic loss of T-cell markers (p < 0.001), BCL6 (p = 0.023) and/or CD10 staining (p = 0.08), and a higher proliferative index (≥ 30%, p = 0.039) favoured these diagnoses over SMLPD. Pathogenic variants were observed by genomic sequencing in 47% of MZL (TNFAIP3 (32%), EP300 (21%), NOTCH2 (16%), KMT2D (16%), CARD11 (10.5%)), 8% of SMLPD (TET2), 40% of PCTFHL (SOCS1 (20%), ARID1A (20%)) and 64% of cAITL (TET2 (63.6%), RHOA (36.4%), NOTCH1 (9%)). This study characterizes the various clinical and histological features between cutaneous lymphomas expressing TFH markers and highlights the value of the interest of screening for genomic mutations in difficult cases.

Acute Myeloid Leukemia-Related Proteins Modified by Ubiquitin and Ubiquitin-like Proteins

Acute myeloid leukemia (AML), the most common form of an acute leukemia, is a malignant disorder of stem cell precursors of the myeloid lineage. Ubiquitination is one of the post-translational modifications (PTMs), and the ubiquitin-like proteins (Ubls; SUMO, NEDD8, and ISG15) play a critical role in various cellular processes, including autophagy, cell-cycle control, DNA repair, signal transduction, and transcription. Also, the importance of Ubls in AML is increasing, with the growing research defining the effect of Ubls in AML. Numerous studies have actively reported that AML-related mutated proteins are linked to Ub and Ubls. The current review discusses the roles of proteins associated with protein ubiquitination, modifications by Ubls in AML, and substrates that can be applied for therapeutic targets in AML.

RANBP10 promotes glioblastoma progression by regulating the FBXW7/c-Myc pathway

RAN binding protein 10 (RANBP10), a ubiquitously expressed and evolutionarily conserved protein, as a RAN-GTP exchange factor (GEF) to regulate several factors involved in cellular progression. Previous studies showed that RANBP10 was overexpressed in prostate cancer cells and was responsible for androgen receptor (AR) activation. However, the biological function of RANBP10 in glioblastoma (GBM) has not been studied. Here, we found that RANBP10 was overexpressed in GBM, and high RANBP10 expression was closely linked to poor survival of patients with GBM. Downregulation of RANBP10 significantly inhibited cell proliferation, migration, invasion, and tumor growth of GBM cells. In addition, we revealed that RANBP10 could suppress the promoter activity of FBXW7, and thereby increase the protein stability of c-Myc in GBM cells. Silencing of FBXW7 in RANBP10-knockdown GBM cells could partly negate the effects induced by RANBP10 downregulation. Taken together, our findings established that RANBP10 significantly promoted GBM progression by control of the FBXW7-c-Myc axis, and suggest that RANBP10 may be a potential target in GBM.

Targeting Notch to Maximize Chemotherapeutic Benefits: Rationale, Advanced Strategies, and Future Perspectives

Simple Summary

The Notch signaling pathway regulates cell proliferation, apoptosis, stem cell self-renewal, and differentiation in a context-dependent fashion both during embryonic development and in adult tissue homeostasis. Consistent with its pleiotropic physiological role, unproper activation of the signaling promotes or counteracts tumor pathogenesis and therapy response in distinct tissues. In the last twenty years, a wide number of studies have highlighted the anti-cancer potential of Notch-modulating agents as single treatment and in combination with the existent therapies. However, most of these strategies have failed in the clinical exploration due to dose-limiting toxicity and low efficacy, encouraging the development of novel agents and the design of more appropriate combinations between Notch signaling inhibitors and chemotherapeutic drugs with improved safety and effectiveness for distinct types of cancer.

Abstract

Notch signaling guides cell fate decisions by affecting proliferation, apoptosis, stem cell self-renewal, and differentiation depending on cell and tissue context. Given its multifaceted function during tissue development, both overactivation and loss of Notch signaling have been linked to tumorigenesis in ways that are either oncogenic or oncosuppressive, but always context-dependent. Notch signaling is critical for several mechanisms of chemoresistance including cancer stem cell maintenance, epithelial-mesenchymal transition, tumor-stroma interaction, and malignant neovascularization that makes its targeting an appealing strategy against tumor growth and recurrence. During the last decades, numerous Notch-interfering agents have been developed, and the abundant preclinical evidence has been transformed in orphan drug approval for few rare diseases. However, the majority of Notch-dependent malignancies remain untargeted, even if the application of Notch inhibitors alone or in combination with common chemotherapeutic drugs is being evaluated in clinical trials. The modest clinical success of current Notch-targeting strategies is mostly due to their limited efficacy and severe on-target toxicity in Notch-controlled healthy tissues. Here, we review the available preclinical and clinical evidence on combinatorial treatment between different Notch signaling inhibitors and existent chemotherapeutic drugs, providing a comprehensive picture of molecular mechanisms explaining the potential or lacking success of these combinations.

Modulation of the Wound Healing through Noncoding RNA Interplay and GSK-3β/NF-κB Signaling Interaction

Diabetic foot ulcers are seriously endangering the physical and mental health of patients. Due to the long duration of inflammation, the treatment of nonhealing wounds in diabetes is one of the most prominent healthcare problems in the world. The nuclear factor kappa B (NF-κB) signaling pathway, a classical pathway that triggers inflammatory response, is regulated by many regulators, such as glycogen synthase kinase 3 beta (GSK-3β). Noncoding RNAs, a large class of molecules that regulate gene expression at the posttranscriptional or posttranslational level, play an important role in various stages of wound healing, especially in the stage of inflammation. Herein, we summarized the roles of noncoding RNAs in the NF-κB/GSK-3β signaling, which might provide new ideas for the treatment of diabetic wound healing.

Regulation of Ribosome Function by RNA Modifications in Hematopoietic Development and Leukemia: It Is Not Only a Matter of m6A

Growth and maturation of hematopoietic stem cells (HSCs) are largely controlled at both transcriptional and post-transcriptional levels. In particular, hematopoietic development requires a tight control of protein synthesis. Furthermore, translational deregulation strongly contributes to hematopoietic malignancies. Researchers have recently identified a new layer of gene expression regulation that consists of chemical modification of RNA species, which led to the birth of the epitranscriptomics field. RNA modifications provide an additional level of control in hematopoietic development by acting as post-transcriptional regulators of lineage-specific genetic programs. Other reviews have already described the important role of the N⁶-methylation of adenosine (m⁶A) within mRNA species in regulating hematopoietic differentiation and diseases. The aim of this review is to summarize the current status of the role of RNA modifications in the regulation of ribosome function, beyond m⁶A. In particular, we discuss the importance of RNA modifications in tRNA and rRNA molecules. By balancing translational rate and fidelity, they play an important role in regulating normal and malignant hematopoietic development.

Circular RNA circRNA_0000094 sponges microRNA-223-3p and up-regulate F-box and WD repeat domain containing 7 to restrain T cell acute lymphoblastic leukemia progression

Circular RNAs (circRNAs) exert crucial regulatory effects in the pathogenesis of multiple tumors. This work aimed to probe into the role of circ_0000094 in T cell acute lymphoblastic leukemia (T-ALL). In this work, quantitative real-time polymerase chain reaction (qRT-PCR) was applied to quantify circ_0000094, miR-223-3p, and F-box and WD repeat domain containing 7 (FBW7) mRNA expressions in lymph node samples from T-ALL patients; Western blot was adopted to examine FBW7 protein expression in T-ALL cells; cell proliferation was detected by cell counting kit-8 (CCK-8) experiment; apoptosis was examined by flow cytometry; Transwell experiments were applied to assess T-ALL cell migration and invasion; the interactions among circ_0000094 and miR-223-3p, and miR-223-3p and FBW7 were validated by bioinformatics prediction, dual-luciferase reporter gene assay, and RNA immunoprecipitation experiment. We reported that, circ_0000094 expression was markedly reduced in T-ALL and circ_0000094 was predominantly located in the cytoplasm; gain-of-function and loss-of-function assays verified that circ_0000094 overexpression remarkably suppressed T-ALL cell proliferation, migration, and invasion, and enhanced apoptosis while knocking down circ_0000094 enhanced the malignant phenotypes of T-ALL cells; "rescue experiments" implied that miR-223-3p mimics partly reversed the inhibitory effects on the malignant phenotype of T-ALL cells due to the circ_0000094 up-regulation; circ_0000094 was proved to be a molecular sponge for miR-223-3p, and it could up-regulate the expression of FBW7 via repressing miR-223-3p expression. Taken together, it was concluded that circ_0000094 impedes T-ALL progression by modulating the miR-223-3p/FBW7 axis.

The Ubiquitin Proteasome System in Hematological Malignancies: New Insight into Its Functional Role and Therapeutic Options

The ubiquitin proteasome system (UPS) is the main cellular degradation machinery designed for controlling turnover of critical proteins involved in cancer pathogenesis, including hematological malignancies. UPS plays a functional role in regulating turnover of key proteins involved in cell cycle arrest, apoptosis and terminal differentiation. When deregulated, it leads to several disorders, including cancer. Several studies indicate that, in some subtypes of human hematological neoplasms such as multiple myeloma and Burkitt’s lymphoma, abnormalities in the UPS made it an attractive therapeutic target due to pro-cancer activity. In this review, we discuss the aberrant role of UPS evaluating its impact in hematological malignancies. Finally, we also review the most promising therapeutic approaches to target UPS as powerful strategies to improve treatment of blood cancers.