Maternal embryonic leucine zipper kinase inhibitor OTSSP167 has preclinical activity in multiple myeloma bone disease

Periodontal Ligament Reactions to Orthodontic Force: A Transcriptomic Study on Maxillary and Mandibular Human Premolars

AIMS

Orthodontic force (OF) induces a variety of reactions in the periodontal ligament (PDL) that could potentially account for individual variability regarding orthodontic tooth movement (OTM). This study investigates the transcriptomic profile of human PDL tissue subjected to OF in vivo for 7 and 28 days, additionally comparing the differences between maxillary and mandibular PDL.

METHODS

Healthy patients requiring orthodontic premolar extractions were randomly assigned to one of three groups: control (CG) where no OF was applied, 7 days and 28 days, where premolars were extracted either 7 or 28 days after the application of a 50-100 g OF. Total RNA was extracted from the PDL tissue and analyzed via RNA-seq. Differentially expressed genes (DEGs) were identified using a false discovery rate and fold change threshold of < 0.05 and ≥ 1.5 respectively. Functional and Protein-Protein Interaction analysis were performed.

RESULTS

After 7 days of OF, the reaction of PDL to OF is characterized by cell responses to stress, increased bone resorption, inflammation and immune response, and decreased bone formation. In contrast, after 28 days, bone regeneration is more prominent, and processes of bone homeostasis, immune response, and cell migration are present. The response of maxillary and mandibular PDL was different. Bone resorption was observed in the maxilla at 7 and 28 days, while in the mandible expression of cell proliferation and transcriptional activity were predominant after 28 days of OF.

CONCLUSIONS

The early reaction of the PDL to OF corresponds with increased bone resorption and decreased bone formation. After 28 days, bone formation became more prominent. The maxillary and mandibular PDL present asynchronous responses during OTM. These findings enhance our comprehension of the mechanisms underlying the origin-specific responses of PDL to different lengths of OF, which is potentially relevant in the development of personalized therapeutic strategies.

Maternal embryonic leucine zipper kinase in tumor cell and tumor microenvironment: Emerging player and promising therapeutic opportunities

Maternal embryonic leucine zipper kinase (MELK) is a member of the AMPK (AMP-activated protein kinase) protein family, which is widely and highly expressed in multiple cancer types. Through direct and indirect interactions with other proteins, it mediates various cascades of signal transduction processes and plays an important role in regulating tumor cell survival, growth, invasion and migration and other biological functions. Interestingly, MELK also plays an important role in the regulation of the tumor microenvironment, which can not only predict the responsiveness of immunotherapy, but also affect the function of immune cells to regulate tumor progression. In addition, more and more small molecule inhibitors have been developed for the target of MELK, which exert important anti-tumor effects and have achieved excellent results in a number of clinical trials. In this review, we outline the structural features, molecular biological functions, potential regulatory mechanisms and important roles of MELK in tumors and tumor microenvironment, as well as substances targeting MELK. Although many molecular mechanisms of MELK in the process of tumor regulation are still unknown, it is worth affirming that MELK is a potential tumor molecular therapeutic target, and its unique superiority and important role provide clues and confidence for subsequent basic research and scientific transformation.

siRNA-Mediated MELK Knockdown Induces Accelerated Wound Healing with Increased Collagen Deposition

Skin wounds remain a significant problem for the healthcare system, affecting the clinical outcome, patients' quality of life, and financial costs. Reduced wound healing times would improve clinical, economic, and social aspects for both patients and the healthcare system. Skin wound healing has been studied for years, but effective therapy that leads to accelerated wound healing remains to be discovered. This study aimed to evaluate the potential of MELK silencing to accelerate wound healing. A vectorless, transient knockdown of the MELK gene using siRNA was performed in a murine skin wound model. The wound size, total collagen, type 3 collagen, vessel size, vessel number, cell proliferation, cell apoptosis, number of mast cells, and immune infiltration by CD45, CD11b, CD45, and CD8a cells were evaluated. We observed that treatment with MELK siRNA leads to significantly faster wound closing associated with increased collagen deposition.

Targeting Ferroptosis in Colorectal Cancer

Ferroptosis is a unique way of regulating cell death (RCD), which is quite different from other programmed cell deaths such as autophagy. It presents iron overload, accumulation of reactive oxygen species (ROS), and lipid peroxidation. A ferroptotic cell usually has an intact cell structure as well as shrinking mitochondria with decreased or vanishing cristae, concentrated membrane density, and ruptured outer membrane. Recently, increasing investigations have discovered that tumor cells have a much greater iron demand than the normal ones, making them more sensitive to ferroptosis. In other words, ferroptosis may inhibit the progress of the tumor, which can be used in the therapy of tumor patients, especially for those with chemotherapy resistance. Therefore, ferroptosis has become one hot spot in the field of tumor research in recent years. Colorectal cancer (CRC) is one common type of gastrointestinal malignancy. The incidence of CRC appears to have an upward trend year by year since the enhancement of living standards. Although surgery and chemoradiotherapy have largely improved the prognosis of patients with CRC, some patients still appear to have severe adverse reactions and drug resistance. Moreover, much research has verified that ferroptosis has a necessary association with the occurrence and progression of gastrointestinal tumors. In this review, we provide a comprehensive evaluation of the main mechanisms of iron metabolism, lipid metabolism, and amino acid metabolism involved in the occurrence of ferroptosis, as well as the research progress of ferroptosis in CRC.

OTSSP167 leads to follicular dysplasia and negatively affects oocyte quality in mice

OTSSP167 is an anti-tumor drug significantly inhibiting tumor growth in xenotransplantation studies using mouse breast, lung, prostate, and pancreatic cancer cell lines. Its phase I clinical trial has been completed, indicating its great potential for future treatment of solid tumors. However, its drug-related adverse effects on reproductive systems have not yet been reported. In this study, we evaluated the effects of OTSSP167 on reproduction of female mice by determining oocyte quality and follicular development. We selected four-week-old female ICR mice for a 21-day intraperitoneal injection of OTSSP167 at a dose of 5mg/kg/d. We found that OTSSP167 could block the meiotic process of oocytes, leading to a decrease in oocyte maturation and ovulated oocyte numbers, as well as a decrease in the quality of oocytes. The results showed that OTSSP167 treatment caused disordered spindle assembly, decreased mitochondria membrane potential, and increased accumulation of reactive oxygen species in oocytes. Further investigation showed that OTSSP167 induced DNA double-strand breaks, as indicated by increased levels of γH2AX in oocytes of primordial follicles and granulosa cells of growing follicles, which induced follicular atresia and decreased the numbers of follicles at various growing stages. Our study suggests that OTSSP167 treatment may have serious effects on the ovary and consequences for female cancer patients, providing strong evidence for the necessity of protecting female fertility in clinical OTSSP167 trials.

Microtubule affinity regulating kinase 4 promoted activation of the NLRP3 inflammasome-mediated pyroptosis in periodontitis

Background

Microtubule dynamics plays a crucial role in the spatial arrangement of cell organelles and activation of the NLRP3 inflammasome.

Purpose

This study aimed to explore whether microtubule affinity regulating kinase 4 (MARK4) can be a therapeutic target of periodontitis by affecting microtubule dynamics and NLRP3 inflammasome-mediated pyroptosis in macrophages.

Materials and Methods

The NLRP3 inflammasome-related genes and MARK4 were measured in the healthy and inflamed human gingival tissues. Bone marrow-derived macrophages (BMDMs) were infected with Porphyromonas gingivalis, while the MARK4 inhibitors (OTSSP167 and Compound 50) and small interference RNA were utilized to restrain MARK4. Apoptosis-associated speck-like protein (ASC) speck was detected by confocal, and levels of interleukin-1β (IL-1β), as well as IL-18, were assessed by ELISA.

Results

Increased staining and transcription of MARK4, NLRP3, ASC, and Caspase-1 were observed in the inflamed gingiva. P. gingivalis infection promoted MARK4 expression and the NLRP3 inflammasome in BMDMs. Inhibition of MARK4 decreased LDH release, IL-1β and IL-18 production, ASC speck formation, and the pyroptosis-related genes transcription. Furthermore, MARK4 inhibition reduced microtubule polymerization and acetylation in P. gingivalis-infected BMDMs.

Conclusions

MARK4 promoted NLRP3 inflammasome activation and pyroptosis in P. gingivalis-infected BMDMs by affecting microtubule dynamics. MARK4 inhibition might be a potential target in regulating the NLRP3 inflammasome during periodontitis progress.

Pharmacological inhibition of MELK restricts ferroptosis and the inflammatory response in colitis and colitis-propelled carcinogenesis

INTRODUCTION

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a group of chronic recurrent and incurable gastrointestinal diseases with an unknown etiology that leads to a high risk of developing colitis-associated colorectal cancer (CRC).

OBJECTIVES

In this study, we measured the expression characteristics of MELK in IBD and CRC tissues and explored the regulatory effect of OTSSP167 (a MELK-selective inhibitor) on the mice models of colitis and colitis-associated carcinogenesis and analyzed the specific molecular mechanisms.

METHODS

DSS-induced colitis and colitis-associated carcinogenesis (CAC) model were treated with MELK inhibitor OTSSP167 then the fight against effect of OTSSP167 in the clinical symptoms of colitis and CAC was measured. In addition, underlying mechanism of OTSSP167 treatment in vitro and vivo including anti-ferroptosis and anti-inflammatory response effect was further explored.

RESULTS

We found that pharmacological inhibition of MELK was indicated to significantly alleviate the inflammatory response in mice with colitis, reduce intestinal damage, and effectively inhibit the occurrence and progression of colitis-propelled carcinogenesis, which was closely related to the regulation of gut microbial composition, and OTSSP167-mediated fecal microbiota transplantation effectively alleviated DSS-induced colitis. In addition, OTSSP167 treatment obviously inhibited ferroptosis in the intestinal tissue and suppressed macrophage infiltration and M1 polarization, which reduced the secretion of pro-inflammatory factors. Further exploration of the molecular mechanism revealed that OTSSP167 inhibited AKT/IKK/P65 and ERK/IKK/P65 signaling cascades both in vivo and in vitro, which may help alleviate intestinal inflammation and control the occurrence of cancer.

CONCLUSION

Our findings lay a theoretical foundation for the use of OTSSP167 as a treatment for IBD and its inhibition of the occurrence of colitis-associated carcinogenesis; additionally, MELK may be a potentially effective target molecule, thus providing more options for clinical treatment.

Analysis of crucial genes, pathways and construction of the molecular regulatory networks in vascular smooth muscle cell calcification

Vascular calcification (VC) accompanies the trans-differentiation of vascular smooth muscle cells (VSMCs) into osteo/chondrocyte-like cells and resembles physiological bone mineralization. However, the molecular mechanisms underlying VC initiation and progression have remained largely elusive. The aim of the present study was to identify the genes and pathways common to VSMC and osteoblast calcification and construct a regulatory network of non-coding RNAs and transcription factors (TFs). To this end, the Gene Expression Omnibus dataset GSE37558 including mRNA microarray data of calcifying VSMCs (CVSMCs) and calcifying osteoblasts (COs) was analyzed. The differentially expressed genes (DEGs) were screened and functionally annotated and the microRNA (miRNA/mRNA)-mRNA, TF-miRNA and long non-coding RNA (lncRNA)-TF regulatory networks were constructed. A total of 318 DEGs were identified in the CVSMCs relative to the non-calcified VSMCs, of which 43 were shared with the COs. The CVSMC-related DEGs were mainly enriched in the functional terms cell cycle, extracellular matrix (ECM), inflammation and chemotaxis-mediated signaling pathways, of which ECM was enriched by the DEGs for the COs as well. The protein-protein interaction network of CVSMCs consisted of 281 genes and 3,650 edges. There were 30 hub genes in this network, including maternal embryonic leucine zipper kinase (MELK), which potentially regulates the differentially expressed TF (DETF) forkhead box (FOX)M1 and is a potential target gene of Homo sapiens miR-485-3p and miR-181d. The TF-miRNA network included 251 TFs and 60 miRNAs, including 10 DETFs such as FOXO1 and snail family transcriptional repressor 2 (SNAI2). Furthermore, the lncRNAs H19 imprinted maternally expressed transcript (H19) and differentiation antagonizing non-protein coding RNA (DANCR) were predicted as the upstream regulators of FOXO1 and SNAI2 in the lncRNA-TF regulatory network. DANCR, MELK and FOXM1 were downregulated, and H19, FOXO1 and SNAI2 were upregulated in the CVSMCs. Taken together, the CVSMCs and COs exhibited similar molecular changes in the ECM. In addition, the MELK-FOXM1, H19/DANCR-FOXO1 and SNAI2 regulatory pathways likely mediate VSMC calcification.

The anti-mitotic agents PTC-028 and PTC596 display potent activity in pre-clinical models of multiple myeloma but challenge the role of BMI-1 as an essential tumour gene

Future progress in the treatment of multiple myeloma (MM) requires both the characterisation of key drivers of the disease and novel, innovative approaches to tackle these vulnerabilities. The present study focussed on the pre-clinical evaluation of a novel drug class, BMI-1 modulators, in MM. We demonstrate potent activity of PTC-028 and PTC596 in a comprehensive set of in vitro and in vivo models, including models of drug resistance and stromal support. Treatment of MM cells with PTC-028 and PTC596 downregulated BMI-1 protein levels, which was found to correlate with drug activity. Surprisingly, BMI-1 was dispensable for the activity of BMI-1 modulators and MM cell growth. Our data rather point to mitotic arrest accompanied by myeloid cell leukaemia-1 (MCL-1) loss as key anti-MM mechanisms and reveal impaired MYC and AKT signalling activity due to BMI-1 modulator treatment. Moreover, we observed a complete eradication of MM after PTC596 treatment in the 5TGM.1 in vivo model and define epigenetic compounds and B cell leukaemia/lymphoma 2 homology domain 3 (BH3) mimetics as promising combination partners. These results bring into question the postulated role of BMI-1 as an essential MM gene and confirm BMI-1 modulators as potent anti-mitotic agents with encouraging pre-clinical activity that supports their rapid translation into clinical trials.

Inhibition of MELK Protooncogene as an Innovative Treatment for Intrahepatic Cholangiocarcinoma

Background and Objectives: Intrahepatic cholangiocarcinoma (iCCA) is a pernicious tumor characterized by a dismal outcome and scarce therapeutic options. To substantially improve the prognosis of iCCA patients, a better understanding of the molecular mechanisms responsible for development and progression of this disease is imperative. In the present study, we aimed at elucidating the role of the maternal embryonic leucine zipper kinase (MELK) protooncogene in iCCA. Materials and Methods: We analyzed the expression of MELK and two putative targets, Forkhead Box M1 (FOXM1) and Enhancer of Zeste Homolog 2 (EZH2), in a collection of human iCCA by real-time RT-PCR and immunohistochemistry (IHC). The effects on iCCA growth of both the multi-kinase inhibitor OTSSP167 and specific small-interfering RNA (siRNA) against MELK were investigated in iCCA cell lines. Results: Expression of MELK was significantly higher in tumors than in corresponding non-neoplastic liver counterparts, with highest levels of MELK being associated with patients' shorter survival length. In vitro, OTSSP167 suppressed the growth of iCCA cell lines in a dose-dependent manner by reducing proliferation and inducing apoptosis. These effects were amplified when OTSSP167 administration was coupled to the DNA-damaging agent doxorubicin. Similar results, but less remarkable, were obtained when MELK was silenced by specific siRNA in the same cells. At the molecular level, siRNA against MELK triggered downregulation of MELK and its targets. Finally, we found that MELK is a downstream target of the E2F1 transcription factor. Conclusion: Our results indicate that MELK is ubiquitously overexpressed in iCCA, where it may represent a prognostic indicator and a therapeutic target. In particular, the combination of OTSSP167 (or other, more specific MELK inhibitors) with DNA-damaging agents might be a potentially effective therapy for human iCCA.

Inhibition of MELK produces potential anti-tumour effects in bladder cancer by inducing G1/S cell cycle arrest via the ATM/CHK2/p53 pathway

We aimed to investigate the biological function of MELK and the therapeutic potential of OTSSP167 in human bladder cancer (BCa). First, we observed overexpression of MELK in BCa cell lines and tissues and found that it was associated with higher tumour stage and tumour grade, which was consistent with transcriptome analysis. High expression of MELK was significantly correlated with poor prognosis in BCa patients, and MELK was found to have a role in the cell cycle, the G1/S transition in mitosis, and DNA repair and replication. Furthermore, BCa cells presented significantly decreased proliferation capacity following silencing of MELK or treatment with OTSSP167 in vitro and in vivo. Functionally, reduction in MELK or treatment of cells with OTSSP167 could induce cell cycle arrest and could suppress migration. In addition, these treatments could activate phosphorylation of ATM and CHK2, which would be accompanied by down‐regulated MDMX, cyclin D1, CDK2 and E2F1; however, p53 and p21 would be activated. Opposite results were observed when MELK expression was induced. Overall, MELK was found to be a novel oncogene in BCa that induces cell cycle arrest via the ATM/CHK2/p53 pathway. OTSSP167 displays potent anti‐tumour activities, which may provide a new molecule‐based strategy for BCa treatment.

Targeting PKCι-PAK1 signaling pathways in EGFR and KRAS mutant adenocarcinoma and lung squamous cell carcinoma

Introduction

p21-activated kinase 1 (PAK1) stimulates growth and metastasis in non-small cell lung cancer (NSCLC). Protein kinase C iota (PKCι) is an enzyme highly expressed in NSCLC, regulating PAK1 signaling. In the present study we explored whether the PKCι-PAK1 signaling pathway approach can be an efficient target in different types of NSCLC cell and mouse models.

Methods

The effect of IPA-3 (PAK1 inhibitor) plus auranofin (PKCι inhibitor) combination was evaluated by cell viability assay, colony formation and western blotting assay, using three types of NSCLC cell lines: EGFR or KRAS mutant adenocarcinoma and squamous cell carcinoma with PAK1 amplification. In addition, for clinical availability, screening for new PAK1 inhibitors was carried out and the compound OTSSP167 was evaluated in combination with auranofin in cell and mice models.

Results

The combination of IPA-3 or OTSSP167 plus auranofin showed high synergism for inhibiting cell viability and colony formation in three cell lines. Mechanistic characterization revealed that this drug combination abrogated expression and activation of membrane receptors and downstream signaling proteins crucial in lung cancer: EGFR, MET, PAK1, PKCι, ERK1/2, AKT, YAP1 and mTOR. A nude mouse xenograft assay demonstrated that this drug combination strongly suppressed tumor volume compared with single drug treatment.

Conclusions

Combination of IPA-3 or OTSSP167 and auranofin was highly synergistic in EGFR or KRAS mutant adenocarcinoma and squamous cell carcinoma cell lines and decreased tumor volume in mice models. It is of interest to further test the targeting of PKCι-PAK1 signaling pathways in EGFR mutant, KRAS mutant and squamous NSCLC patients.

Higher maternal embryonic leucine zipper kinase mRNA expression level is a poor prognostic factor in non-small-cell lung carcinoma patients

Aim: To elucidate potential prognostic significance of MELK mRNA expression in non-small-cell lung carcinoma patients. Methods: A loop algorithm based on R software was used to select genes with the best prognostic value. Mantel-Haenszel method and functional enrichment analysis were used to perform this analysis. Results: MELK mRNA expression level in tumor tissue is significantly higher than that in normal/benign tissue (p < 0.001), and gradually increases from stage I to IV (lung adenocarcinoma: p = 0.011; lung squamous cell carcinoma: p = 0.002), and is negatively correlated with prognosis in lung adenocarcinoma patients (HR: 2.025 in univariate analysis; HR: 2.162 in multivariate analysis). However, it does not show a significant correlation in lung squamous cell carcinoma patients. Conclusion: MELK is a poor biomarker for non-small-cell lung carcinoma patients and can potentially be used as a therapeutic target.

Emerging protein kinase inhibitors for the treatment of multiple myeloma

Introduction: Significant advances have been made during the last two decades in terms of new therapeutic options but also of innovative approaches to diagnosis and management of multiple myeloma (MM). While patient survival has been significantly prolonged, most patients relapse. Including the milestone approval of the first kinase inhibitor imatinib mesylate for CML in 2001, 48 small molecule protein kinase (PK) inhibitors have entered clinical practice until now. However, no PK inhibitor has been approved for MM therapy yet. Areas covered: This review article summarizes up-to-date knowledge on the pathophysiologic role of PKs in MM. Derived small molecules targeting receptor tyrosine kinases (RTKs), the Ras/Raf/MEK/MAPK- pathway, the PI3K/Akt/mTOR- pathway as well as Bruton tyrosine kinase (BTK), Aurora kinases (AURK), and cyclin-dependent kinases (CDKs) are most promising. Preclinical as well as early clinical data focusing on these molecules will be presented and critically reviewed. Expert opinion: Current MM therapy is directed against general vulnerabilities. Novel therapeutic strategies, inhibition of PKs in particular, are directed to target tumor-specific driver aberrations such as genetic abnormalities and microenvironment-driven deregulations. Results of ongoing Precision Medicine trials with PK inhibitors alone or in combination with other agents are eagerly awaited and hold the promise of once more improving MM patient outcome.

Exosomes play a role in multiple myeloma bone disease and tumor development by targeting osteoclasts and osteoblasts

Progression of multiple myeloma (MM) is largely dependent on the bone marrow (BM) microenvironment wherein communication through different factors including extracellular vesicles takes place. This cross-talk not only leads to drug resistance but also to the development of osteolysis. Targeting vesicle secretion could therefore simultaneously ameliorate drug response and bone disease. In this paper, we examined the effects of MM exosomes on different aspects of osteolysis using the 5TGM1 murine model. We found that 5TGM1 sEVs, or ‘exosomes’, not only enhanced osteoclast activity, they also blocked osteoblast differentiation and functionality in vitro. Mechanistically, we could demonstrate that transfer of DKK-1 led to a reduction in Runx2, Osterix, and Collagen 1A1 in osteoblasts. In vivo, we uncovered that 5TGM1 exosomes could induce osteolysis in a similar pattern as the MM cells themselves. Blocking exosome secretion using the sphingomyelinase inhibitor GW4869 not only increased cortical bone volume, but also it sensitized the myeloma cells to bortezomib, leading to a strong anti-tumor response when GW4869 and bortezomib were combined. Altogether, our results indicate an important role for exosomes in the BM microenvironment and suggest a novel therapeutic target for anti-myeloma therapy.