Effects of Neddylation and mTOR Inhibition in Acute Myelogenous Leukemia

RAPSYN-mediated neddylation of BCR-ABL alternatively determines the fate of Philadelphia chromosome-positive leukemia

Philadelphia chromosome-positive (Ph+) leukemia is a fatal hematological malignancy. Although standard treatments with tyrosine kinase inhibitors (TKIs) have achieved remarkable success in prolonging patient survival, intolerance, relapse, and TKI resistance remain serious issues for patients with Ph+ leukemia. Here, we report a new leukemogenic process in which RAPSYN and BCR-ABL co-occur in Ph+ leukemia, and RAPSYN mediates the neddylation of BCR-ABL. Consequently, neddylated BCR-ABL enhances the stability by competing its c-CBL-mediated degradation. Furthermore, SRC phosphorylates RAPSYN to activate its NEDD8 E3 ligase activity, promoting BCR-ABL stabilization and disease progression. Moreover, in contrast to in vivo ineffectiveness of PROTAC-based degraders, depletion of RAPSYN expression, or its ligase activity decreased BCR-ABL stability and, in turn, inhibited tumor formation and growth. Collectively, these findings represent an alternative to tyrosine kinase activity for the oncoprotein and leukemogenic cells and generate a rationale of targeting RAPSYN-mediated BCR-ABL neddylation for the treatment of Ph+ leukemia.

Feasibility of pevonedistat combined with azacitidine, fludarabine, cytarabine in pediatric relapsed/refractory AML: Results from COG ADVL1712

BACKGROUND

Outcomes for children with relapsed/refractory (R/R) acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) are poor, and new therapies are needed. Pevonedistat is an inhibitor of the NEDD-8 activating enzyme, a key regulator of the ubiquitin proteasome system that is responsible for protein turnover, with protein degradation regulating cell growth and survival.

PROCEDURE

We evaluated the feasibility, toxicity, and pharmacokinetics (PK) of pevonedistat (20 mg/m2 days 1, 3, 5) in combination with azacitidine, fludarabine, cytarabine (aza-FLA) in children with R/R AML and MDS (NCT03813147). Twelve patients were enrolled, median age was 13 years (range 1-21). Median number of prior chemotherapeutic regimens was two (range one to five), and two (25%) patients had prior hematopoietic cell transplantation. Diagnoses were AML NOS (n = 10, 83%), acute monocytic leukemia (n = 1), and therapy-related AML (n = 1).

RESULTS

Overall, three of 12 (25%) patients experienced DLTs. The day 1 mean ± SD (n = 12) Cmax , VSS , T1/2 , and CL were 223 ± 91 ng/mL, 104 ± 53.8 L/m2 , 4.3 ± 1.2 hours, and 23.2 ± 6.9 L/h/m2 , respectively. T1/2 , VSS , and Cmax , but not CL, were significantly different between age groups. The overall response rate was 25%, with n = 3 patients achieving a complete remission with incomplete hematologic recovery (CRi).

CONCLUSIONS

Pevonedistat 20 mg/m2 combined with Aza-FLA was tolerable in children with R/R AML with similar toxicity profile to other intensive AML regimens. However, within the confines of a phase 1 study, we did not observe that the pevonedistat + Aza-FLA combination demonstrated significant anti-leukemic activity.

NEDD8-Activating Enzyme Inhibitor MLN4924 Inhibits Both the Tumor Stroma and Angiogenesis in Pancreatic Cancer via Gli1 and REDD1

PURPOSE

Pancreatic cancer is characterized by a dense desmoplasia stroma, which hinders efficient drug delivery and plays a critical role in tumor progression and metastasis. MLN4924 is a first-in-class NEDD8-activating enzyme inhibitor that exhibits anti-tumor activities toward pancreatic cancer, and given the comprehensive effects that MLN4924 could have, we ask what impact MLN4924 would have on the stroma of pancreatic cancer and its underlying mechanisms.

METHODS

Primary pancreatic stellate cells (PSCs) and human HMEC-1 cells were treated with MLN4924 in vitro. The proliferation and extracellular matrix protein levels of PSCs were tested, and their relationship with transcription factor Gli1 in PSCs was investigated. The angiogenic phenotypes of HMEC-1 cells were evaluated using capillary-like tube formation assay, and their relationship with REDD1 in HMEC-1 cells was investigated.

RESULTS

In this study, we found that MLN4924 inhibited the proliferation of pancreatic stellate cells and their secretion of collagen and CXCL-1, and the collagen secretion inhibiting effect of MLN4924 was related with transcription factor Gli1. MLN4924 inhibited multiple angiogenic phenotypes of HMEC-1 cells, and mTOR agonist partially relieved the inhibition of MLN4924 on HEMCs. MLN4924 increased the expression of REDD1 and REDD1 knockdown promoted the angiogenic phenotypes of HMEC-1 cells.

CONCLUSIONS

Our study suggests that MLN4924 inhibits both the tumor stroma and angiogenesis in pancreatic cancer, and the inhibition effect is related with Gli1 in pancreatic stellate cells and REDD1 in vascular endothelial cells, respectively.

Inhibition of NEDD8 NEDDylation induced apoptosis in acute myeloid leukemia cells via p53 signaling pathway

MLN4924 is a potent and selective small-molecule inhibitor of NEDD8-activating enzyme, which showed antitumor effect in several types of malignant tumor types. However, the mechanism of action of MLN4924 in acute myeloid leukemia (AML) requires further investigation. Real-time fluorescent quantitative polymerase chain reaction (RT-qPCR) was conducted to detect the mRNA levels of genes. Gene expression was knocked down by short hairpin RNA (shRNA). Moreover, the protein expression was detected by Western blotting (WB) assay. The proliferation and apoptosis of AML cells were measured by Cell Counting Kit-8 (CCK8) assay and flow cytometry (FCM). In the present study, we observed that the mRNA expression levels of NEDD8, UBA3, UBE2M and RBX1 in AML patients were up-regulated compared with healthy controls, which were correlated with worse overall survival (OS) of patients. Besides, knockdown of UBA3, UBE2M and RBX1 inhibited the NEDDylation of CULs and increased the protein expression of p53 and p21 in MOLM-13 cell line. In AML cells, MLN4924 inhibited cell proliferation, promoted cell apoptosis, and induced cell cycle arrest at the G₂/M phase. As revealed by experiments in vivo and in vitro, the NEDDylation of CULs was significantly inhibited and the p53 signaling pathway was activated after MLN4924 treatment. So, we concluded that NEDD8, UBA3, UBE2M and RBX1 may serve as the prognostic biomarkers and novel therapeutic targets for AML. Inhibition of the NEDDylation pathway resulted in an anti-leukemia effect by activating the p53 signaling pathway.

Rapamycin inhibits the progression of human acute myeloid leukemia by regulating circ_0094100/miR-217/ATP1B1 axis

Rapamycin has been reported to inhibit the progression of diverse tumor cells. However, the functions of rapamycin in acute myeloid leukemia (AML) are little known. Cell Counting Kit-8 (CCK-8) assay was conducted to evaluate cell viability. Flow cytometry analysis was employed to analyze cell apoptosis and cell cycle process. Quantitative real-time polymerase chain reaction (qRT-PCR) assay was performed to determine the levels of circRNA_0094100 (circ_0094100) and microRNA-217 (miR-217). Western blot assay was carried out to measure the protein levels of proliferating cell nuclear antigen (PCNA), cyclin D1, B-cell lymphoma-2 (Bcl-2) and ATPase Na+/K+ transporting subunit beta 1 (ATP1B1). Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were conducted to verify the relationship between miR-217 and circ_0094100 or ATP1B1. Rapamycin treatment suppressed AML cell viability and promoted apoptosis in a dose-dependent way. Circ_0094100 was elevated in AML tissues and cells. Moreover, the circ_0094100 level was reduced in AML cells treated with rapamycin. Circ_0094100 knockdown further inhibited rapamycin-mediated AML cell viability, and cell cycle, and promoted cell apoptosis. Circ_0094100 silencing reduced the protein levels of PCNA, cyclin D1, and Bcl-2 in rapamycin-treated AML cells. For mechanism analysis, circ_0094100 acted as the sponge for miR-217 and miR-217 inhibition reversed circ_0094100 knockdown-mediated malignant behaviors of rapamycin-treated AML cells. Furthermore, miR-217 overexpression suppressed cell viability and cell cycle and facilitated apoptosis in rapamycin-exposed AML cells, which were abolished by increasing ATP1B1. Rapamycin inhibited AML cell viability and cell cycle process and induced apoptosis through regulating circ_0094100/miR-217/ATP1B1 axis.

Integrative genomic analysis of a novel small nucleolar RNAs prognostic signature in patients with acute myelocytic leukemia

This study mainly used The Cancer Genome Atlas (TCGA) RNA sequencing dataset to screen prognostic snoRNAs of acute myeloid leukemia (AML), and used for the construction of prognostic snoRNAs signature for AML. A total of 130 AML patients with RNA sequencing dataset were used for prognostic snoRNAs screenning. SnoRNAs co-expressed genes and differentially expressed genes (DEGs) were used for functional annotation, as well as gene set enrichment analysis (GSEA). Connectivity Map (CMap) also used for potential targeted drugs screening. Through genome-wide screening, we identified 30 snoRNAs that were significantly associated with the prognosis of AML. Then we used the step function to screen a prognostic signature composed of 14 snoRNAs (SNORD72, SNORD38, U3, SNORA73B, SNORD79, SNORA73, SNORD12B, SNORA74, SNORD116-12, SNORA65, SNORA14, snoU13, SNORA75, SNORA31), which can significantly divide AML patients into high- and low-risk groups. Through GSEA, snoRNAs co-expressed genes and DEGs functional enrichment analysis, we screened a large number of potential functional mechanisms of this prognostic signature in AML, such as phosphatidylinositol 3-kinase-Akt, Wnt, epithelial to mesenchymal transition, T cell receptors, NF-kappa B, mTOR and other classic cancer-related signaling pathways. In the subsequent targeted drug screening using CMap, we also identified six drugs that can be used for AML targeted therapy, they were alimemazine, MG-262, fluoxetine, quipazine, naltrexone and oxybenzone. In conclusion, our current study was constructed an AML prognostic signature based on the 14 prognostic snoRNAs, which may serve as a novel prognostic biomarker for AML.

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.

Elaborated study of Cu(II) carbosilane metallodendrimers bearing substituted iminopyridine moieties as antitumor agents

Iminopyridine-decorated carbosilane metallodendrimers have recently emerged as a promising strategy in the treatment of cancer diseases. Their unique features such as the nanometric size, the multivalent nature and the structural perfection offer an extraordinary platform to explore structure-to-property relationships. Herein, we showcase the outstanding impact on the antitumor activity of a parameter not explored before: the iminopyridine substituents in meta position. New Cu(II) carbosilane metallodendrimers, bearing methyl or methoxy substituents in the pyridine ring, were synthesized and thoroughly characterized. Electron Paramagnetic Resonance (EPR) was exploited to unveil the properties of the metallodendrimers. This study confirmed the presence of different coordination modes of the Cu(II) ion (Cu-N₂O₂, Cu-N₄ and Cu-O₄), whose ratios were determined by the structural features of the dendritic molecules. These metallodendrimers exhibited IC₅₀ values in the low micromolar range (<6 μM) in tumor cell lines such as HeLa and MCF-7. The subsequent in vitro assays on both healthy (PBMC) and tumor (U937) myeloid cells revealed two key facts which improved the cytotoxicity and selectivity of the metallodrug: First, maximizing the Cu-N₂O₂ coordination mode; second, adequately selecting the pair ring-substituent/metal-counterion. The most promising candidates, G₁(-CH₃)Cl (8) and G₁(-OCH₃)NO₃(17), exhibited a substantial increase in the antitumor activity in U937 tumor cells, compared to the non-substituted counterparts, probably through two different ROS-production pathways.

Drug Repurposing Approach against Novel Coronavirus Disease (COVID-19) through Virtual Screening Targeting SARS-CoV-2 Main Protease

Simple Summary

With the urgent necessity of potential treatment against novel coronavirus disease, we used several computational methods to search for active drugs from an extensive database. The results of our investigation suggested several established drugs that can be subjected to further analysis for the treatment of novel coronavirus disease. Various methods used in this study proved the effectiveness of the retrieved drugs. Therefore, our findings highly recommend the mentioned drugs to be scrutinized to discover drugs against novel coronavirus.

Abstract

Novel coronavirus disease (COVID-19) was identified from China in December 2019 and spread rapidly through human-to-human transmission, affecting so many people worldwide. Until now, there has been no specific treatment against the disease and repurposing of the drug. Our investigation aimed to screen potential inhibitors against coronavirus for the repurposing of drugs. Our study analyzed sequence comparison among SARS-CoV, SARS-CoV-2, and MERS-CoV to determine the identity matrix using discovery studio. SARS-CoV-2 M^pro was targeted to generate an E-pharmacophore hypothesis to screen drugs from the DrugBank database having similar features. Promising drugs were used for docking-based virtual screening at several precisions. Best hits from virtual screening were subjected to MM/GBSA analysis to evaluate binding free energy, followed by the analysis of binding interactions. Furthermore, the molecular dynamics simulation approaches were carried out to assess the docked complex’s conformational stability. A total of 33 drug classes were found from virtual screening based on their docking scores. Among them, seven potential drugs with several anticancer, antibiotic, and immunometabolic categories were screened and showed promising MM/GBSA scores. During interaction analysis, these drugs exhibited different types of hydrogen and hydrophobic interactions with amino acid residue. Besides, 17 experimental drugs selected from virtual screening might be crucial for drug discovery against COVID-19. The RMSD, RMSF, SASA, Rg, and MM/PBSA descriptors from molecular dynamics simulation confirmed the complex’s firm nature. Seven promising drugs for repurposing against SARS-CoV-2 main protease (M^pro), namely sapanisertib, ornidazole, napabucasin, lenalidomide, daniquidone, indoximod, and salicylamide, could be vital for the treatment of COVID-19. However, extensive in vivo and in vitro studies are required to evaluate the mentioned drug’s activity.

Targeting Cullin-RING E3 Ligases for Radiosensitization: From NEDDylation Inhibition to PROTACs

As a dynamic regulator for short-lived protein degradation and turnover, the ubiquitin-proteasome system (UPS) plays important roles in various biological processes, including response to cellular stress, regulation of cell cycle progression, and carcinogenesis. Over the past decade, research on targeting the cullin-RING (really interesting new gene) E3 ligases (CRLs) in the UPS has gained great momentum with the entry of late-phase clinical trials of its novel inhibitors MLN4924 (pevonedistat) and TAS4464. Several preclinical studies have demonstrated the efficacy of MLN4924 as a radiosensitizer, mainly due to its unique cytotoxic properties, including induction of DNA damage response, cell cycle checkpoints dysregulation, and inhibition of NF-κB and mTOR pathways. Recently, the PROteolysis TArgeting Chimeras (PROTACs) technology was developed to recruit the target proteins for CRL-mediated polyubiquitination, overcoming the resistance that develops inevitably with traditional targeted therapies. First-in-class cell-permeable PROTACs against critical radioresistance conferring proteins, including the epidermal growth factor receptor (EGFR), androgen receptor (AR) and estrogen receptor (ER), cyclin-dependent kinases (CDKs), MAP kinase kinase 1 (MEK1), and MEK2, have emerged in the past 5 years. In this review article, we will summarize the most important research findings of targeting CRLs for radiosensitization.

Rapamycin enhanced the antitumor effects of doxorubicin in myelogenous leukemia K562 cells by downregulating the mTOR/p70S6K pathway

Chronic myelogenous leukemia (CML) is a common hematological malignancy. Some patients progressing to the blast phase develop chemotherapeutic drug resistance. In the authors' previous study, it was found that the mammalian target of rapamycin (mTOR) pathway was activated in CML and that rapamycin inhibited the proliferation of K562 cells. Targeting the mTOR pathway may be used in combination with chemotherapeutic drugs to enhance their efficacy and overcome multidrug resistance. The aim of the present study was to investigate the effects of rapamycin and doxorubicin on K562 cell proliferation following the combination treatment, and further focus on confirming whether rapamycin enhanced the antitumor effects of doxorubicin by downregulating the mTOR/ribosomal protein S6 kinase (p70S6K) pathway. It was found that rapamycin and doxorubicin significantly decreased the viability of K562 cells. The apoptotic cells were more frequently detected in rapamycin and doxorubicin treatment groups (25.50±1.25%). Both drugs decreased Bcl-2 and increased Bax expression in K562 cells. Rapamycin and doxorubicin also reduced the phosphorylation levels of mTOR and p70S6K. Meanwhile, p70S6K-targeting small interfering (si)RNA and doxorubicin inhibited cell proliferation and regulated key factors of the cell cycle. In addition, the exposure of cells to p70S6K siRNA and doxorubicin significantly increased cell apoptosis, as compared with single treatment. These results suggested that rapamycin could enhance the antitumor effects of doxorubicin on K562 cells by downregulating mTOR/p70S6K signaling. Targeting the mTOR/p70S6K pathway may be a new therapeutic approach for leukemia.