Inhibition of elongation factor-2 kinase augments the antitumor activity of Temozolomide against glioma

Systematic Review of Molecular Targeted Therapies for Adult-Type Diffuse Glioma: An Analysis of Clinical and Laboratory Studies

Gliomas are the most common brain tumor in adults, and molecularly targeted therapies to treat gliomas are becoming a frequent topic of investigation. The current state of molecular targeted therapy research for adult-type diffuse gliomas has yet to be characterized, particularly following the 2021 WHO guideline changes for classifying gliomas using molecular subtypes. This systematic review sought to characterize the current state of molecular target therapy research for adult-type diffuse glioma to better inform scientific progress and guide next steps in this field of study. A systematic review was conducted in accordance with PRISMA guidelines. Studies meeting inclusion criteria were queried for study design, subject (patients, human cell lines, mice, etc.), type of tumor studied, molecular target, respective molecular pathway, and details pertaining to the molecular targeted therapy-namely the modality, dose, and duration of treatment. A total of 350 studies met the inclusion criteria. A total of 52 of these were clinical studies, 190 were laboratory studies investigating existing molecular therapies, and 108 were laboratory studies investigating new molecular targets. Further, a total of 119 ongoing clinical trials are also underway, per a detailed query on clinicaltrials.gov. GBM was the predominant tumor studied in both ongoing and published clinical studies as well as in laboratory analyses. A few studies mentioned IDH-mutant astrocytomas or oligodendrogliomas. The most common molecular targets in published clinical studies and clinical trials were protein kinase pathways, followed by microenvironmental targets, immunotherapy, and cell cycle/apoptosis pathways. The most common molecular targets in laboratory studies were also protein kinase pathways; however, cell cycle/apoptosis pathways were the next most frequent target, followed by microenvironmental targets, then immunotherapy pathways, with the wnt/β-catenin pathway arising in the cohort of novel targets. In this systematic review, we examined the current evidence on molecular targeted therapy for adult-type diffuse glioma and discussed its implications for clinical practice and future research. Ultimately, published research falls broadly into three categories-clinical studies, laboratory testing of existing therapies, and laboratory identification of novel targets-and heavily centers on GBM rather than IDH-mutant astrocytoma or oligodendroglioma. Ongoing clinical trials are numerous in this area of research as well and follow a similar pattern in tumor type and targeted pathways as published clinical studies. The most common molecular targets in all study types were protein kinase pathways. Microenvironmental targets were more numerous in clinical studies, whereas cell cycle/apoptosis were more numerous in laboratory studies. Immunotherapy pathways are on the rise in all study types, and the wnt/β-catenin pathway is increasingly identified as a novel target.

Anoikis resistance in diffuse glioma: The potential therapeutic targets in the future

Glioma is the most common malignant intracranial tumor and exhibits diffuse metastasis and a high recurrence rate. The invasive property of glioma results from cell detachment. Anoikis is a special form of apoptosis that is activated upon cell detachment. Resistance to anoikis has proven to be a protumor factor. Therefore, it is suggested that anoikis resistance commonly occurs in glioma and promotes diffuse invasion. Several factors, such as integrin, E-cadherin, EGFR, IGFR, Trk, TGF-β, the Hippo pathway, NF-κB, eEF-2 kinase, MOB2, hypoxia, acidosis, ROS, Hsp and protective autophagy, have been shown to induce anoikis resistance in glioma. In our present review, we aim to summarize the underlying mechanism of resistance and the therapeutic potential of these molecules.

Pro-inflammatory cytokines in cystic glioblastoma: A quantitative study with a comparison with bacterial brain abscesses. With an MRI investigation of displacement and destruction of the brain tissue surrounding a glioblastoma

Cystic glioblastomas are aggressive primary brain tumors that may both destroy and displace the surrounding brain tissue as they grow. The mechanisms underlying these tumors’ destructive effect could include exposure of brain tissue to tumor-derived cytokines, but quantitative cytokine data are lacking. Here, we provide quantitative data on leukocyte markers and cytokines in the cyst fluid from 21 cystic glioblastomas, which we compare to values in 13 brain abscess pus samples. The concentration of macrophage/microglia markers sCD163 and MCP-1 was higher in glioblastoma cyst fluid than in brain abscess pus; lymphocyte marker sCD25 was similar in cyst fluid and pus, whereas neutrophil marker myeloperoxidase was higher in pus. Median cytokine levels in glioblastoma cyst fluid were high (pg/mL): TNF-α: 32, IL-6: 1064, IL-8: 23585, tissue factor: 28, the chemokine CXCL1: 639. These values were not significantly different from values in pus, pointing to a highly pro-inflammatory glioblastoma environment. In contrast, levels of IFN-γ, IL-1β, IL-2, IL-4, IL-10, IL-12, and IL-13 were higher in pus than in glioblastoma cyst fluid. Based on the quantitative data, we show for the first time that the concentrations of cytokines in glioblastoma cyst fluid correlate with blood leukocyte levels, suggesting an important interaction between glioblastomas and the circulation. Preoperative MRI of the cystic glioblastomas confirmed both destruction and displacement of brain tissue, but none of the cytokine levels correlated with degree of brain tissue displacement or peri-tumoral edema, as could be assessed by MRI. We conclude that cystic glioblastomas are highly pro-inflammatory environments that interact with the circulation and that they both displace and destroy brain tissue. These observations point to the need for neuroprotective strategies in glioblastoma therapy, which could include an anti-inflammatory approach.

Eukaryotic Extension Factor 2 Kinase may Affect the Occurrence and Development of Glioblastoma Through Immune Cell Infiltration

Glioblastoma (GBM) is one of the most common malignancies among primary brain tumors in adults, featuring a poor prognosis and a high recurrence rate. Eukaryotic elongation factor 2 kinase (eEF2K) is a calcium/calmodulin-dependent protein kinase that is involved in promoting tumor cell proliferation, migration, invasion, and survival. However, its expression level in GBM, its prognostic impact and correlation with immune infiltration are not yet known. In this study, we used The Cancer Genome Atlas (TCGA) database to explore the potential molecular mechanisms of eEF2K in GBM development and clinical prognosis in terms of gene expression, survival status, immune infiltration, and associated cellular pathways. We found that eEF2K expression levels were elevated in GBM, but eEF2K was not associated with the prognosis of GBM patients; eEF2K expression in GBM was associated with multiple immune cell infiltrations. These results show a statistical correlation between eEF2K expression and the development of GBM and immune cell infiltration, which helps us to understand the roles of eEF2K in GBM from different perspectives.

Targeting Protein Translation in Melanoma by Inhibiting EEF-2 Kinase Regulates Cholesterol Metabolism though SREBP2 to Inhibit Tumour Development

Decreasing the levels of certain proteins has been shown to be important for controlling cancer but it is currently unknown whether proteins could potentially be targeted by the inhibiting of protein synthesis. Under this circumstance, targeting protein translation could preferentially affect certain pathways, which could then be of therapeutic advantage when treating cancer. In this report, eukaryotic elongation factor-2 kinase (EEF2K), which is involved in protein translation, was shown to regulate cholesterol metabolism. Targeting EEF2K inhibited key parts of the cholesterol pathway in cancer cells, which could be rescued by the addition of exogenous cholesterol, suggesting that it is a potentially important pathway modulated by targeting this process. Specifically, targeting EEF2K significantly suppressed tumour cell growth by blocking mRNA translation of the cholesterol biosynthesis transcription factor, sterol regulatory element-binding protein (SREBP) 2, and the proteins it regulates. The process could be rescued by the addition of LDL cholesterol taken into the cells via non-receptor-mediated-uptake, which negated the need for SREBP2 protein. Thus, the levels of SREBP2 needed for cholesterol metabolism in cancer cells are therapeutically vulnerable by targeting protein translation. This is the first report to suggest that targeting EEF2K can be used to modulate cholesterol metabolism to treat cancer.

Fluoxetine regulates eEF2 activity (phosphorylation) via HDAC1 inhibitory mechanism in an LPS-induced mouse model of depression

BACKGROUND

Selective serotonin reuptaker inhibitors, including fluoxetine, are widely studied and prescribed antidepressants, while their exact molecular and cellular mechanism are yet to be defined. We investigated the involvement of HDAC1 and eEF2 in the antidepressant mechanisms of fluoxetine using a lipopolysaccharide (LPS)-induced depression-like behavior model.

METHODS

For in vivo analysis, mice were treated with LPS (2 mg/kg BW), fluoxetine (20 mg/kg BW), HDAC1 activator (Exifone: 54 mg/kg BW) and NH125 (1 mg/kg BW). Depressive-like behaviors were confirmed via behavior tests including OFT, FST, SPT, and TST. Cytokines were measured by ELISA while Iba-1 and GFAP expression were determined by immunofluorescence. Further, the desired gene expression was measured by immunoblotting. For in vitro analysis, BV2 cell lines were cultured; treated with LPS, exifone, and fluoxetine; collected; and analyzed.

RESULTS

Mice treated with LPS displayed depression-like behaviors, pronounced neuroinflammation, increased HDAC1 expression, and reduced eEF2 activity, as accompanied by altered synaptogenic factors including BDNF, SNAP25, and PSD95. Fluoxetine treatment exhibited antidepressant effects and ameliorated the molecular changes induced by LPS. Exifone, a selective HDAC1 activator, reversed the antidepressant and anti-inflammatory effects of fluoxetine both in vivo and in vitro, supporting a causing role of HDAC1 in neuroinflammation allied depression. Further molecular mechanisms underlying HDAC1 were explored with NH125, an eEF2K inhibitor, whose treatment reduced immobility time, altered pro-inflammatory cytokines, and NLRP3 expression. Moreover, NH125 treatment enhanced eEF2 and GSK3β activities, BDNF, SNAP25, and PSD95 expression, but had no effects on HDAC1.

CONCLUSIONS

Our results showed that the antidepressant effects of fluoxetine may involve HDAC1-eEF2 related neuroinflammation and synaptogenesis.

Targeting kinases with thymoquinone: a molecular approach to cancer therapeutics

Kinases are enzymes that are important for cellular functions, but their overexpression has strong connections with carcinogenesis, rendering them important targets for anticancer drugs. Thymoquinone (TQ) is a natural compound with proven anticancer activities, at least in preclinical studies. TQ can target several kinases, including phosphoinositide 3-kinase (PI3K), mitogen-activated protein kinase (MAPK), Janus kinase/signal transducers and activators of transcription (JAK/STAT), polo-like kinase 1 (PLK1), and tyrosine kinase in different cancer cells and animal models. Inhibiting the activity of kinases or suppressing their expression might be among the mechanisms of TQ anticancer activity. In this review, we discuss the role of TQ in kinase regulation in different cancer models.

eEF2 kinase mediated autophagy as a potential therapeutic target for paclitaxel-resistant triple-negative breast cancer

Background

Triple-negative breast cancers (TNBCs) are initially responsive to chemotherapy, but most recurrent TNBCs develop resistance. Autophagy is believed to play dual roles in cancer and might contribute to chemoresistance. In this study, we aimed to investigate the role of autophagy and its regulator, eukaryotic elongation factor 2 kinase (eEF2K), in determining the biological nature of TNBC.

Methods

We used in vitro models of TNBC, namely, paclitaxel-resistant cell lines derived from sensitive cell lines. Various approaches to measuring autophagy flux were applied. We assessed the effects of inhibiting autophagy and silencing eEF2K on cell viability, tumor formation and invasion. We also collected residual tumor samples from 222 breast cancer patients who underwent neoadjuvant chemotherapy and measured eEF2K and LC3 expression levels by immunohistochemistry (IHC). Multivariate survival analysis was used to determine prognostic variables.

Results

Compared to the parental lines, the chemoresistant lines exhibited enhanced starvation-stimulated autophagy and showed significant decreases in cell viability, growth and invasion upon treatment with autophagy inhibitors. eEF2K silencing also resulted in the suppression of autophagic activity and in aggressive biological behavior. In the survival analysis, residual tumor LC3 (P=0.001) and eEF2K (P=0.027) expression levels were independent prognostic factors for patients who underwent neoadjuvant chemotherapy, especially in those with TNBC.

Conclusions

Our study indicated that eEF2K and autophagy play key roles in the maintenance of aggressive tumor behavior and chemoresistance in resistant TNBC. eEF2K silencing may be a novel strategy for the treatment of TNBC.

Autophagic and Apoptotic Pathways as Targets for Chemotherapy in Glioblastoma

Glioblastoma multiforme is the most malignant and aggressive type of brain tumor, with a mean life expectancy of less than 15 months. This is due in part to the high resistance to apoptosis and moderate resistant to autophagic cell death in glioblastoma cells, and to the poor therapeutic response to conventional therapies. Autophagic cell death represents an alternative mechanism to overcome the resistance of glioblastoma to pro-apoptosis-related therapies. Nevertheless, apoptosis induction plays a major conceptual role in several experimental studies to develop novel therapies against brain tumors. In this review, we outline the different components of the apoptotic and autophagic pathways and explore the mechanisms of resistance to these cell death pathways in glioblastoma cells. Finally, we discuss drugs with clinical and preclinical use that interfere with the mechanisms of survival, proliferation, angiogenesis, migration, invasion, and cell death of malignant cells, favoring the induction of apoptosis and autophagy, or the inhibition of the latter leading to cell death, as well as their therapeutic potential in glioma, and examine new perspectives in this promising research field.

Thymoquinone inhibits cell proliferation, migration, and invasion by regulating the elongation factor 2 kinase (eEF-2K) signaling axis in triple-negative breast cancer

BACKGROUND/PURPOSE

Triple-negative breast cancer (TNBC) is the most aggressive and chemoresistant subtype of breast cancer. Therefore, new molecular targets and treatments need to be developed to improve poor patient prognosis and survival. We have previously shown that eukaryotic elongation factor 2 kinase (eEF-2K) is highly expressed in TNBC cells, is associated with poor patient survival and prognosis, and promotes cell proliferation, migration, and invasion. In vivo targeting of eEF-2K significantly reduces the tumor growth of orthotopic TNBC xenograft mouse models, suggesting that eEF-2K may serve as a potential novel therapeutic target.

METHODS/RESULTS

In the current study, we identified thymoquinone (TQ), an active ingredient of Nigella sativa, as a potential safe and effective eEF-2K inhibitor in TNBC. We demonstrated for the first time that TQ inhibits the protein and mRNA expression of eEF-2K, as well as the clinically relevant downstream targets, including Src/FAK and Akt, and induces the tumor suppressor miR-603, in response to NF-kB inhibition. This effect was associated with a significant decrease in the proliferation, colony formation, migration, and invasion of TNBC cells. Furthermore, systemic in vivo injection of TQ (20 and 100 mg/kg) significantly reduced the growth of MDA-MB-231 tumors and inhibited the eEF-2K expression in an orthotopic tumor model in mice.

CONCLUSION

Our study provides first evidence that TQ treatment inhibits cell proliferation, migration/invasion, and tumor growth, in part through the inhibition of eEF-2K signaling in TNBC. Thus, our findings suggest that systemic TQ treatment may be used as a targeted therapeutic strategy for the inhibition of eEF-2K in TNBC tumor growth and progression.

Strategies against methicillin-resistant Staphylococcus aureus persisters

Chronic Staphylococcus aureus infections are complicated by frequent relapses not only from the development of drug resistance to conventional antibiotics, but also through the formation of persister bacterial cells. Bacterial persisters are in a transient, metabolically inactive state, making conventional antibiotics that target essential cellular growth processes ineffective, resulting in high clinical failure rates of antibiotic chemotherapy. The development of new antibiotics against persistent S. aureus is an urgent issue. Over the last decade, new strategies to identify S. aureus persister-active compounds have been proposed. This review summarizes the proposed targets, antipersister compounds and innovative methods that may augment conventional antibiotics against S. aureus persisters. The reviewed antipersister strategies can be summarized as two broad categories; directly targeting growth-independent targets and potentiating existing, ineffective antibiotics by aiding uptake or accessibility.

MicroRNA 603 acts as a tumor suppressor and inhibits triple-negative breast cancer tumorigenesis by targeting elongation factor 2 kinase

Triple negative breast cancer (TNBC) is an aggressive type of breast cancer characterized by the absence of defined molecular targets, including estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and is associated with high rates of relapse and distant metastasis despite surgery and adjuvant chemotherapy. The lack of effective targeted therapies for TNBC represents an unmet therapeutic challenge. Eukaryotic elongation factor 2 kinase (eEF2K) is an atypical calcium/calmodulin-dependent serine/threonine kinase that promotes TNBC tumorigenesis, progression, and drug resistance, representing a potential novel molecular target. However, the mechanisms regulating eEF2K expression are unknown. Here, we report that eEF2K protein expression is highly up-regulated in TNBC cells and patient tumors and it is associated with poor patient survival and clinical outcome. We found that loss/reduced expression of miR-603 leads to eEF2K overexpression in TNBC cell lines. Its expression results in inhibition of eEF2K by directly targeting the 3-UTR and the inhibition of tumor cell growth, migration and invasion in TNBC. In vivo therapeutic gene delivery of miR-603 into TNBC xenograft mouse models by systemic administration of miR-603-nanoparticles led to a significant inhibition of eEF2K expression and tumor growth, which was associated with decreased activity of the downstream targets of eEF2K, including Src, Akt, cyclin D1 and c-myc. Our findings suggest that miR-603 functions as a tumor suppressor and loss of miR-603 expression leads to increase in eEF2K expression and contributes to the growth, invasion, and progression of TNBC. Taken together, our data suggest that miR-603-based gene therapy is a potential strategy against TNBC.

Calyxin Y sensitizes cisplatin-sensitive and resistant hepatocellular carcinoma cells to cisplatin through apoptotic and autophagic cell death via SCF βTrCP-mediated eEF2K degradation

The down-regulation of eukaryotic elongation factor-2 kinase (eEF2K) is associated with an enhancement in the sensitivity of malignant cells to chemotherapeutic agents. In this study, we found that the silencing of eEF2K enhanced cisplatin (CDDP)-induced cytotoxicity in CDDP-sensitive (HepG2) and resistant (HepG2/CDDP) cells. Calyxin Y, a unique chalcone diarylheptanoid adduct, down-regulated eEF2K by promoting Skp1-Cul1-F-box protein (SCF) β-transducin repeat-containing protein (βTrCP)-mediated protein degradation and synergistically enhanced the cytotoxicity of CDDP. Subsequently, we identified a potential mechanism of this cooperative interaction by showing that the combination of calyxin Y and CDDP enhanced apoptotic cell death via mitochondrial dysfunction. In addition, the combination induced autophagy, which contributed to the synergistic cytotoxic effect. Further research revealed that calyxin Y synergistically sensitized HepG2 and HepG2/CDDP cells to CDDP through enhanced apoptotic and autophagic cell death via the SCF βTrCP-eEF2K pathway. Finally, in vivo studies demonstrated that calyxin Y could enhance the response of HepG2/CDDP cells to CDDP in xenograft models with low systemic toxicity. Thus, the combination of calyxin Y and CDDP might represent an attractive therapeutic strategy for the treatment of chemotherapy-sensitive and resistant hepatocellular carcinoma cells.

Rutin increases the cytotoxicity of temozolomide in glioblastoma via autophagy inhibition

The chemotherapeutic agent temozolomide (TMZ) is widely used in the treatment of glioblastoma multiforme (GBM). Rutin, a citrus flavonoid ecglycoside found in edible plants, has neuroprotective and anticancer activities. This study aimed to investigate the efficacy and the underlying mechanisms of rutin used in combination with TMZ in GBM. In vitro cell viability assay demonstrated that rutin alone had generally low cytotoxic effect, but it enhanced the efficacy of TMZ in a dose-dependent manner. Subcutaneous and orthotopic xenograft studies also showed that tumor volumes were significantly lower in mice receiving combined TMZ/Rutin treatment as compared to TMZ or rutin alone treatment. Moreover, immunoblotting analysis showed that TMZ activated JNK activity to induce protective response autophagy, which was blocked by rutin, resulting in decreased autophagy and increased apoptosis, suggesting that rutin enhances TMZ efficacy both in vitro and in vivo via inhibiting JNK-mediated autophagy in GBM. The combination rutin with TMZ may be a potentially useful therapeutic approach for GBM patient.

Inhibition of eEF-2 kinase sensitizes human nasopharyngeal carcinoma cells to lapatinib-induced apoptosis through the Src and Erk pathways

Background

Previous studies have reported that eEF-2 kinase is associated with tumour cell sensitivity to certain therapies. In the present study, we investigated the relationship between eEF-2 kinase and lapatinib, a dual inhibitor of EGFR and HER-2, in nasopharyngeal carcinoma (NPC) cells.

Methods

The effect of treatment on the growth and proliferation of NPC cells was measured by three methods: cell counting, crystal violet staining and colony counting. Apoptosis was evaluated by flow cytometry to determine Annexin V-APC/7-AAD and cleaved PARP levels, and the results were further confirmed by Western blot analysis. The expression of eEF-2 kinase and the impacts of different treatments on different signalling pathways were analysed by Western blot analysis.

Results

The expression of eEF-2 kinase was significantly associated with NPC cell sensitivity to lapatinib. Therefore, suppression of this kinase could increase the cytocidal effect of lapatinib, as well as reduce cell viability and colony formation. Furthermore, inhibition of eEF-2 kinase, by either RNA interference (eEF-2 kinase siRNA or shRNA) or pharmacological inhibition (NH125), enhanced lapatinib-induced apoptosis of NPC cells. The results also showed that lapatinib combined with NH125 had a synergistic effect in NPC cells. In addition, mechanistic analyses revealed that downregulation of the ERK1/2 and Src pathways, but not the AKT pathway, was involved in this sensitizing effect.

Conclusions

The results of this study suggest that targeting eEF-2 kinase may improve the efficacy of therapeutic interventions such as lapatinib in NPC cells.

Structural Basis for the Recognition of Eukaryotic Elongation Factor 2 Kinase by Calmodulin

Binding of Ca(2+)-loaded calmodulin (CaM) activates eukaryotic elongation factor 2 kinase (eEF-2K) that phosphorylates eEF-2, its only known cellular target, leading to a decrease in global protein synthesis. Here, using an eEF-2K-derived peptide (eEF-2KCBD) that encodes the region necessary for its CaM-mediated activation, we provide a structural basis for their interaction. The striking feature of this association is the absence of Ca(2+) from the CaM C-lobe sites, even under high Ca(2+) conditions. eEF-2KCBD engages CaM largely through the C lobe of the latter in an anti-parallel 1-5-8 hydrophobic mode reinforced by a pair of unique electrostatic contacts. Sparse interactions of eEF-2KCBD with the CaM N lobe results in persisting inter-lobe mobility. A conserved eEF-2K residue (W85) anchors it to CaM by inserting into a deep hydrophobic cavity within the CaM C lobe. Mutation of this residue (W85S) substantially weakens interactions between full-length eEF-2K and CaM in vitro and reduces eEF-2 phosphorylation in cells.

Targeting autophagy to sensitive glioma to temozolomide treatment

Temozolomide (TMZ), an alkylating agent, is widely used for treating primary and recurrent high-grade gliomas. However, the efficacy of TMZ is often limited by the development of resistance. Recently, studies have found that TMZ treatment could induce autophagy, which contributes to therapy resistance in glioma. To enhance the benefit of TMZ in the treatment of glioblastomas, effective combination strategies are needed to sensitize glioblastoma cells to TMZ. In this regard, as autophagy could promote cell survival or autophagic cell death, modulating autophagy using a pharmacological inhibitor, such as chloroquine, or an inducer, such as rapamycin, has received considerably more attention. To understand the effectiveness of regulating autophagy in glioblastoma treatment, this review summarizes reports on glioblastoma treatments with TMZ and autophagic modulators from in vitro and in vivo studies, as well as clinical trials. Additionally, we discuss the possibility of using autophagy regulatory compounds that can sensitive TMZ treatment as a chemotherapy for glioma treatment.

Identification of an Antimicrobial Agent Effective against Methicillin-Resistant Staphylococcus aureus Persisters Using a Fluorescence-Based Screening Strategy

Persisters are a subpopulation of normal bacterial cells that show tolerance to conventional antibiotics. Persister cells are responsible for recalcitrant chronic infections and new antibiotics effective against persisters would be a major development in the treatment of these infections. Using the reporter dye SYTOX Green that only stains cells with permeabilized membranes, we developed a fluorescence-based screening assay in a 384-well format for identifying compounds that can kill methicillin-resistant Staphylococcus aureus (MRSA) persisters. The assay proved robust and suitable for high throughput screening (Z`-factor: >0.7). In screening a library of hits from a previous screen, which identified compounds that had the ability to block killing of the nematode Caenorhabditis by MRSA, we discovered that the low molecular weight compound NH125, a bacterial histidine kinase inhibitor, kills MRSA persisters by causing cell membrane permeabilization, and that 5 μg/mL of the compound can kill all cells to the limit of detection in a 10⁸ CFU/mL culture of MRSA persisters within 3h. Furthermore, NH125 disrupts 50% of established MRSA biofilms at 20 μg/mL and completely eradicates biofilms at 160 μg/mL. Our results suggest that the SYTOX Green screening assay is suitable for large-scale projects to identify small molecules effective against MRSA persisters and should be easily adaptable to a broad range of pathogens that form persisters. Since NH125 has strong bactericidal properties against MRSA persisters and high selectivity to bacteria, we believe NH125 is a good anti-MRSA candidate drug that should be further evaluated.

Rac1/Pak1/p38/MMP-2 Axis Regulates Angiogenesis in Ovarian Cancer

PURPOSE

Zoledronic acid is being increasingly recognized for its antitumor properties, but the underlying functions are not well understood. In this study, we hypothesized that zoledronic acid inhibits ovarian cancer angiogenesis preventing Rac1 activation.

EXPERIMENTAL DESIGN

The biologic effects of zoledronic acid were examined using a series of in vitro [cell invasion, cytokine production, Rac1 activation, reverse-phase protein array, and in vivo (orthotopic mouse models)] experiments.

RESULTS

There was significant inhibition of ovarian cancer (HeyA8-MDR and OVCAR-5) cell invasion as well as reduced production of proangiogenic cytokines in response to zoledronic acid treatment. Furthermore, zoledronic acid inactivated Rac1 and decreased the levels of Pak1/p38/matrix metalloproteinase-2 in ovarian cancer cells. In vivo, zoledronic acid reduced tumor growth, angiogenesis, and cell proliferation and inactivated Rac1 in both HeyA8-MDR and OVCAR-5 models. These in vivo antitumor effects were enhanced in both models when zoledronic acid was combined with nab-paclitaxel.

CONCLUSIONS

Zoledronic acid has robust antitumor and antiangiogenic activity and merits further clinical development as ovarian cancer treatment.