Maternal embryonic leucine zipper kinase is a novel target for diffuse large B cell lymphoma and mantle cell lymphoma

DDX56 promotes EMT and cancer stemness via MELK-FOXM1 axis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major global cause of death, with epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC)-like properties contributing to its metastasis. DEAD box helicase 56 (DDX56) is involved in carcinogenesis, but its role in EMT induction and stem phenotype maintenance is unclear. This study assessed the impact of DDX56 absence on HCC cell stemness and EMT. DDX56 was found to be overexpressed in HCC tissues, correlating with disease stage and prognosis. In vitro, DDX56 stimulated tumor cell proliferation, migration, invasion, EMT, and stemness. It also enhanced maternal embryonic leucine-zipper kinase (MELK)-mediated forkhead box protein M1 (FOXM1) expression, regulating cancer stemness and malignant traits. In vivo, DDX56 knockdown in tumor-bearing mice reduced tumorigenicity and lung metastasis by modulating the MELK-FOXM1 signaling pathway. Collectively, DDX56 initiates stem cell-like traits in HCC and promotes EMT via MELK-FOXM1 activation, shedding light on HCC pathogenesis and suggesting a potential anti-cancer therapeutic target.

Antileukemic properties of the kinase inhibitor OTSSP167 in T-cell acute lymphoblastic leukemia

Novel drugs are needed to increase treatment response in children with high-risk T-cell acute lymphoblastic leukemia (T-ALL). Following up on our previous report on the activation of the MAP2K7-JNK pathway in pediatric T-ALL, here we demonstrate that OTSSP167, recently shown to inhibit MAP2K7, has antileukemic capacity in T-ALL. OTSSP167 exhibited dose-dependent cytotoxicity against a panel of T-ALL cell lines with IC50 in the nanomolar range (10-50 nM). OTSSP167 induces apoptosis and cell cycle arrest in T-ALL cell lines, associated at least partially with the inhibition of MAP2K7 kinase activity and lower activation of its downstream substrate, JNK. Other leukemic T-cell survival pathways, such as mTOR and NOTCH1 were also inhibited. Daily intraperitoneal administration of 10 mg/kg OTSSP167 was well tolerated, with mice showing no hematological toxicity, and effective at reducing the expansion of human T-ALL cells in a cell-based xenograft model. The same dosage of OTSSP167 efficiently controlled the leukemia burden in the blood, bone marrow, and spleen of 3 patient-derived xenografts, which resulted in prolonged survival. OTSSP167 exhibited synergistic interactions when combined with dexamethasone, L-asparaginase, vincristine, and etoposide. Our findings reveal novel antileukemic properties of OTSSP167 in T-ALL and support the use of OTSSP167 as an adjuvant drug to increase treatment response and reduce relapses in pediatric T-ALL.

Preclinical assessment of synergistic efficacy of MELK and CDK inhibitors in adrenocortical cancer

BACKGROUND

Adrenocortical cancer (ACC) is a rare and aggressive cancer with dismal 5-year survival due to a lack of effective treatments. We aimed to identify a new effective combination of drugs and investigated their synergistic efficacy in ACC preclinical models.

METHODS

A quantitative high-throughput drug screening of 4,991 compounds was performed on two ACC cell lines, SW13 and NCI-H295R, based on antiproliferative effect and caspase-3/7 activity. The top candidate drugs were pairwise combined to identify the most potent combinations. The synergistic efficacy of the selected inhibitors was tested on tumorigenic phenotypes, such as cell proliferation, migration, invasion, spheroid formation, and clonogenicity, with appropriate mechanistic validation by cell cycle and apoptotic assays and protein expression of the involved molecules. We tested the efficacy of the drug combination in mice with luciferase-tagged human ACC xenografts. To study the mRNA expression of target molecules in ACC and their clinical correlations, we analyzed the Gene Expression Omnibus and The Cancer Genome Atlas.

RESULTS

We chose the maternal embryonic leucine zipper kinase (MELK) inhibitor (OTS167) and cyclin-dependent kinase (CDK) inhibitor (RGB-286638) because of their potent synergy from the pairwise drug combination matrices derived from the top 30 single drugs. Multiple publicly available databases demonstrated overexpression of MELK, CDK1/2, and partnering cyclins mRNA in ACC, which were independently associated with mortality and other adverse clinical features. The drug combination demonstrated a synergistic antiproliferative effect on ACC cells. Compared to the single-agent treatment groups, the combination treatment increased G2/M arrest, caspase-dependent apoptosis, reduced cyclins A2, B1, B2, and E2 expression, and decreased cell migration and invasion with reduced vimentin. Moreover, the combination effectively decreased Foxhead Box M1, Axin2, glycogen synthase kinase 3-beta, and β-catenin. A reduction in p-stathmin from the combination treatment destabilized microtubule assembly by tubulin depolymerization. The drug combination treatment in mice with human ACC xenografts resulted in a significantly lower tumor burden than those treated with single-agents and vehicle control groups.

CONCLUSIONS

Our preclinical study revealed a novel synergistic combination of OTS167 and RGB-286638 in ACC that effectively targets multiple molecules associated with ACC aggressiveness. A phase Ib/II clinical trial in patients with advanced ACC is therefore warranted.

Computational Exploration of Maternal Embryonic Leucine Zipper Kinase (MELK) As a Cancer Drug Target

Maternal embryonic leucine zipper kinase (MELK) is of vital importance due to its significant role in cancer development and its association with poor prognosis in different cancers. Here, we employed several computer aided drug design approaches to shortlist potential binding molecules of MELK. For virtual screening, asinex oncology library (containing 6334 drugs) and comprehensive marine natural products database (containing approximately 32,000 drugs) were used. The study identified two drug molecules: Top-2 and Top-3 as high affinity binding MELK molecules compared to the control co-crystalized Top-1 inhibitor. Both the shortlisted compounds and the control showed high stable binding free energy and high GOLD score. The compounds and control also reported stable dynamics with root mean square deviations (RMSD) value ∼ 2 Å in 500 ns. Similarly, the MELK active site residues were observed in good stability with the compounds. Further, it was noticed the compounds/control formed multiple hydrogen bonds with the MELK active pocket residues which is the main reason of high intermolecular stability. Atomic level binding free energies determined van der Waals and electrostatic energies to play vital role in stable complex formation. From drug likeness and pharmacokinetics perspective, the compounds are ideal molecules for further investigation. Overall, the results are promising and might be tested in in vivo and in vitro studies against MELK.

A synthetic lethal screen identifies HDAC4 as a potential target in MELK overexpressing cancers

Maternal embryonic leucine zipper kinase (MELK) is frequently overexpressed in cancer, but the role of MELK in cancer is still poorly understood. MELK was shown to have roles in many cancer-associated processes including tumor growth, chemotherapy resistance, and tumor recurrence. To determine whether the frequent overexpression of MELK can be exploited in therapy, we performed a high-throughput screen using a library of Saccharomyces cerevisiae mutants to identify genes whose functions become essential when MELK is overexpressed. We identified two such genes: LAG2 and HDA3. LAG2 encodes an inhibitor of the Skp, Cullin, F-box containing (SCF) ubiquitin-ligase complex, while HDA3 encodes a subunit of the HDA1 histone deacetylase complex. We find that one of these synthetic lethal interactions is conserved in mammalian cells, as inhibition of a human homolog of HDA3 (Histone Deacetylase 4, HDAC4) is synthetically toxic in MELK overexpression cells. Altogether, our work identified a novel potential drug target for tumors that overexpress MELK.

Integrative analysis of hub genes and key pathway in two subtypes of diffuse large B-cell lymphoma by bioinformatics and basic experiments

Background

The germinal center B‐cell (GCB) and activated B‐cell (ABC) subtypes of diffuse large B‐cell lymphoma (DLBCL) have a significant difference in prognosis. This study aimed to identify potential hub genes, and key pathways involved in them.

Methods

Databases including Gene Expression Omnibus (GEO), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and STRING were accessed to obtain potential crucial genes and key pathways associated with the GCB and ABC. Then qRT‐PCR and Western blot experiments were performed to verify the most clinically significant gene and pathway.

Results

Three cohort datasets from the GEO database were analyzed, including 195 GCB and 169 ABC samples. We identified 1113 differentially expressed genes (DEGs) between the GCB and ABC subtypes. The DEGs were mainly enriched in biological processes (BP). The KEGG analysis showed enrichment in cell cycle and Wnt signaling pathways. We selected the top 10 genes using the STRING database and Cytoscape software. We used 5 calculation methods of the cytoHubba plugin, and found 3 central genes (IL‐10, CD44, CCND2). CCND2 was significantly related to the prognosis of DLBCL patients. Besides, our experimental results demonstrated a significantly higher expression of CCND2 in the ABC‐type cell line than in the GCB‐type; it was proportional to the expression of key proteins in the Wnt signaling pathway.

Conclusion

CCND2 overexpression and Wnt pathway activation might be the main reasons for the poor prognosis of ABC‐DLBCL.

OTS167 blocks FLT3 translation and synergizes with FLT3 inhibitors in FLT3 mutant acute myeloid leukemia

Internal tandem duplication (-ITD) mutations of Fms-like tyrosine kinase 3 (FLT3) provide growth and pro-survival signals in the context of established driver mutations in FLT3 mutant acute myeloid leukemia (AML). Maternal embryonic leucine zipper kinase (MELK) is an aberrantly expressed gene identified as a target in AML. The MELK inhibitor OTS167 induces cell death in AML including cells with FLT3 mutations, yet the role of MELK and mechanisms of OTS167 function are not understood. OTS167 alone or in combination with tyrosine kinase inhibitors (TKIs) were used to investigate the effect of OTS167 on FLT3 signaling and expression in human FLT3 mutant AML cell lines and primary cells. We describe a mechanism whereby OTS167 blocks FLT3 expression by blocking FLT3 translation and inhibiting phosphorylation of eukaryotic initiation factor 4E–binding protein 1 (4E-BP1) and eukaryotic translation initiation factor 4B (eIF4B). OTS167 in combination with TKIs results in synergistic induction of FLT3 mutant cell death in FLT3 mutant cell lines and prolonged survival in a FLT3 mutant AML xenograft mouse model. Our findings suggest signaling through MELK is necessary for the translation and expression of FLT3-ITD, and blocking MELK with OTS167 represents a viable therapeutic strategy for patients with FLT3 mutant AML.