Antimalarial drug mefloquine inhibits nuclear factor kappa B signaling and induces apoptosis in colorectal cancer cells

Investigating the therapeutic promise of drug-repurposed-loaded nanocarriers: A pioneering strategy in advancing colorectal cancer treatment

Globally, colorectal cancer is a major health problem that ranks in third place in terms of occurrence and second in terms of mortality worldwide. New cases increase annually, with the absence of effective therapies, especially for metastatic colorectal cancer, emphasizing the need for novel therapeutic approaches. Although conventional treatments are commonly used in oncotherapy, their success rate is low, which leads to the exploration of novel technologies. Recent efforts have focused on developing safe and efficient cancer nanocarriers. With their nanoscale properties, nanocarriers have the potential to utilize internal metabolic modifications amid cancer and healthy cells. Drug repurposing is an emerging strategy in cancer management as it is a faster, cheaper, and safer method than conventional drug development. However, most repurposed drugs are characterized by low-key pharmacokinetic characteristics, such as poor aqueous solubility, permeability, retention, and bioavailability. Nanoparticles formulations and delivery have expanded over the past few decades, creating opportunities for drug repurposing and promises as an advanced cancer modality. This review provides a concise and updated overview of colorectal cancer treatment regimens and their therapeutic limitations. Furthermore, the chemotherapeutic effect of various FDA-approved medications, including statins, non-steroidal anti-inflammatory drugs, antidiabetic and anthelmintic agents, and their significance in colorectal cancer management. Along with the role of various nanocarrier systems in achieving the desired therapeutic outcomes of employing these redefined drugs.

Pharmacology Progresses and Applications of Chloroquine in Cancer Therapy

Chloroquine is a common antimalarial drug and is listed in the World Health Organization Standard List of Essential Medicines because of its safety, low cost and ease of use. Besides its antimalarial property, chloroquine also was used in anti-inflammatory and antivirus, especially in antitumor therapy. A mount of data showed that chloroquine mainly relied on autophagy inhibition to exert its antitumor effects. However, recently, more and more researches have revealed that chloroquine acts through other mechanisms that are autophagy-independent. Nevertheless, the current reviews lacked a comprehensive summary of the antitumor mechanism and combined pharmacotherapy of chloroquine. So here we focused on the antitumor properties of chloroquine, summarized the pharmacological mechanisms of antitumor progression of chloroquine dependent or independent of autophagy inhibition. Moreover, we also discussed the side effects and possible application developments of chloroquine. This review provided a more systematic and cutting-edge knowledge involved in the anti-tumor mechanisms and combined pharmacotherapy of chloroquine in hope of carrying out more in-depth exploration of chloroquine and obtaining more clinical applications.

Combining Mefloquine with an Mcl-1 Inhibitor as a Novel Therapeutic Strategy for the Treatment of Nasopharyngeal Carcinoma

Considering the established pharmacokinetics and toxicity profiles, drug repurposing has emerged as an alternative therapeutic approach for treating cancer. Mefloquine has previously demonstrated inhibitory effects on multiple cancer types. This study aims to explore the impact of mefloquine on nasopharyngeal carcinoma (NPC). We found that mefloquine, at pharmacologically achievable concentrations, displayed anti-NPC activity while sparing normal counterparts. Mefloquine inhibits proliferation and induces death by reducing the levels of Cyclin A2, Bcl-2, and Bcl-xL. Intriguingly, we observed an increase in the levels of the anti-apoptotic protein Mcl-1. Mefloquine exerts its effects on NPC cells by inducing lysosomal-mediated ROS production, and the heightened expression of Mcl-1 is a consequence of ROS generation in mefloquine-treated NPC cells. The combination of an Mcl-1 inhibitor with mefloquine synergistically inhibits NPC growth in mice without causing substantial toxicity. These findings demonstrate the effectiveness and limited toxicity of mefloquine as a monotherapy and in combination with an Mcl-1 inhibitor. Our research underscores the promise of the mefloquine and Mcl-1 inhibitor combination as a potential treatment for NPC. Additionally, the elevation of Mcl-1 is a compensatory response in cells exposed to oxidative stress, offering a potential target to overcome resistance induced by pro-oxidant therapies.

Current trends and future prospects of drug repositioning in gastrointestinal oncology

Gastrointestinal (GI) cancers comprise a significant number of cancer cases worldwide and contribute to a high percentage of cancer-related deaths. To improve survival rates of GI cancer patients, it is important to find and implement more effective therapeutic strategies with better prognoses and fewer side effects. The development of new drugs can be a lengthy and expensive process, often involving clinical trials that may fail in the early stages. One strategy to address these challenges is drug repurposing (DR). Drug repurposing is a developmental strategy that involves using existing drugs approved for other diseases and leveraging their safety and pharmacological data to explore their potential use in treating different diseases. In this paper, we outline the existing therapeutic strategies and challenges associated with GI cancers and explore DR as a promising alternative approach. We have presented an extensive review of different DR methodologies, research efforts and examples of repurposed drugs within various GI cancer types, such as colorectal, pancreatic and liver cancers. Our aim is to provide a comprehensive overview of employing the DR approach in GI cancers to inform future research endeavors and clinical trials in this field.

Small-molecule drugs of colorectal cancer: Current status and future directions

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the world's fourth most deadly cancer. CRC, as a genetic susceptible disease, faces significant challenges in optimizing prognosis through optimal drug treatment modalities. In recent decades, the development of innovative small-molecule drugs is expected to provide targeted interventions that accurately address the different molecular characteristics of CRC. Although the clinical application of single-target drugs is limited by the heterogeneity and high metastasis of CRC, novel small-molecule drug treatment strategies such as dual/multiple-target drugs, drug repurposing, and combination therapies can help overcome these challenges and provide new insights for improving CRC treatment. In this review, we focus on the current status of a range of small molecule drugs that are being considered for CRC therapy, including single-target drugs, dual/multiple-target drugs, drug repurposing and combination strategies, which will pave the way for targeting CRC vulnerabilities with small-molecule drugs in future personalized treatment.

OPTIMIZATION AND CHARACTERIZATION OF ESSENTIAL OILS FORMULATION FOR ENHANCED STABILITY AND DRUG DELIVERY SYSTEM OF MEFLOQUINE

Objective: This work aims to choose suitable essential oil formulations to improve the bioavailability and long-term aqueous stability of mefloquine in drug delivery systems. Methods: Oil phases of pomegranate oil, black cumin seed oil, and garlic oil. To choose the proper oil and surfactant for creating pseudo-ternary phase diagrams, cremophore EL, tween®20 and tween®80 (surfactants), and brij 35 (co-surfactants) were used in a variety of concentrations and combinations (Smix). Mefloquine was estimated to be soluble in a variety of oils, surfactants, and co-surfactants. Drug solubility, drug release research, thermodynamic stability, mean hydrodynamic size and zeta potential. Results: Garlic with smix of cremophore EL and brij 35, Pomegranate with Tween 2.0, and Black cumin seed oil with Tween 80 showed the highest solubilization and emulsification capabilities and were further investigated using ternary phase diagrams. When combined with the co-surfactants under investigation, cremophore EL demonstrated a greater self-emulsification zone than tween® 80 and tween 20. Garlic oil, cremophore EL, and brij 35 nanoemulsion showed smaller size, greater zeta potential, less emulsification time, high transmittance, and better drug solubility than microemulsion formulations on especially those made with tween®20 and tween 80. Mefloquine loaded garlic oil nanoemulsion showed considerably low release in body fluid (32.48%) and a good release in intestinal fluid (82.78%) by 12 h in a drug release study. Conclusion: Garlic oil as the oil phase and a mixture of cremophore EL and brij 35 as the surfactant phase are ideal surfactants and co-surfactant for mefloquine loaded garlic oil nanoemulsion with greater drug release in release kinetics investigation.

Intestinal microbiomics and hepatic metabolomics insights into the potential mechanisms of probiotic Bifidobacterium pseudolongum CCFM1253 preventing acute liver injury in mice

BACKGROUND

Bifidobacterium pseudolongum is widely exists in mammal gut and its abundance is associated with human and animal health. The present study aimed to investigate the potential mechanisms of B. pseudolongum CCFM1253 on protecting against lipopolysaccharide (LPS)-induced acute liver injury (ALI) by metagenomic analysis and liver metabolomic profiles.

RESULTS

Bifidobacterium pseudolongum CCFM1253 preintervention remarkably attenuated the influence of LPS on serum alanine transaminase and aspartate amino transferase activities. B. pseudolongum CCFM1253 preintervention remarkably attenuated the inflammation responses (tumor necrosis factor-α, interleukin-1β, and interleukin-6) and elevated antioxidative enzymes activities [total antioxidant capacity, superoxide dismutase, catalase, and glutathione peroxidase] in ALI mice by intervening in the Nf-kβ and Nrf2 pathways, respectively. Bifidobacterium pseudolongum CCFM1253 treatment elevated the proportion of Alistipes and Bifidobacterium, and decreased the proportion of uncultured Bacteroidales bacterium, Muribaculum, Parasutterella and Ruminococcaceae UCG-010 in ALI mice, which were strongly correlated with the inhibition of inflammation responses and oxidative stress. Untargeted liver metabolomics exhibited that the hepatoprotective efficacy of B. pseudolongum CCFM1253 might be achieved by altering liver metabolites-related riboflavin metabolism, phenylalanine metabolism, alanine, citrate cycle (tricarboxylic acid cycle), and so on. Furthermore, riboflavin exposure could control the contents of malondialdehyde, superoxide dismutase, and catalase in hydrogen peroxide-treated HepG2 cells.

CONCLUSION

Bifidobacterium pseudolongum CCFM1253 can effectively alleviate inflammatory response and oxidative stress, and regulate the intestinal microbiota composition and liver metabolism, and elevate the liver riboflavin content in LPS-treated mice. Therefore, B. pseudolongum CCFM1253 could serves as a potential probiotic to ameliorate the host health. © 2023 Society of Chemical Industry.

Mefloquine loaded niosomes as a promising approach for the treatment of acute and chronic toxoplasmosis

Toxoplasmosis is a disease with a worldwide distribution and significant morbidity and mortality. In search of effective treatment, mefloquine (MQ) was repurposed and loaded with niosomes to treat acute and chronic phases of toxoplasmosis in experimental mice. Mice were orally inoculated with 20 cysts of Toxoplasma gondii (ME 49 strain) for the acute model of infection and 10 cysts for the chronic model of infection. Infected mice were dosed with MQ solution or MQ-niosomes at 50 mg/kg/day, starting from the second day post-infection (PI) (acute model) or the fifth week PI (chronic model), and this was continued for six consecutive days. The effects of MQ solution and MQ-niosomes were compared with a pyrimethamine/sulfadiazine (PYR/SDZ) dosing combination as mortality rates, brain cyst number, inflammatory score, and immunohistochemical studies that included an estimation of apoptotic cells (TUNEL assays). In the acute infection model, MQ solution and MQ-niosomes significantly reduced the mortality rate from 45% to 25 and 10%, respectively, compared with infected untreated controls, and decreased the number of brain cysts by 51.5% and 66.9%, respectively. In the chronic infection model, cyst reduction reached 80.9% and 12.3% for MQ solution and MQ-niosomes treatments, respectively. MQ-niosomes significantly decreased inflammation induced by acute or chronic T. gondii infection. Additionally, immunohistochemical analysis revealed that MQ solution and MQ-niosomes significantly increased the number of TUNEL-positive cells in brain tissue, indicative of induction of apoptosis. Collectively, these results indicate that MQ-niosomes may provide a useful delivery strategy to treat both acute and chronic toxoplasmosis.

Mefloquine induces ER stress and apoptosis in BRAFi-resistant A375-BRAFV600E /NRASQ61K malignant melanoma cells targeting intracranial tumors in a bioluminescent murine model

Molecularly targeted therapeutics have revolutionized the treatment of BRAFV600E -driven malignant melanoma, but the rapid development of resistance to BRAF kinase inhibitors (BRAFi) presents a significant obstacle. The use of clinical antimalarials for the investigational treatment of malignant melanoma has shown only moderate promise, attributed mostly to inhibition of lysosomal-autophagic adaptations of cancer cells, but identification of specific antimalarials displaying single-agent antimelanoma activity has remained elusive. Here, we have screened a focused library of clinically used artemisinin-combination therapeutic (ACT) antimalarials for the apoptotic elimination of cultured malignant melanoma cell lines, also examining feasibility of overcoming BRAFi-resistance comparing isogenic melanoma cells that differ only by NRAS mutational status (BRAFi-sensitive A375-BRAFV600E /NRASQ61 vs. BRAFi-resistant A375-BRAFV600E /NRASQ61K ). Among ACT antimalarials tested, mefloquine (MQ) was the only apoptogenic agent causing melanoma cell death at low micromolar concentrations. Comparative gene expression-array analysis (A375-BRAFV600E /NRASQ61 vs. A375-BRAFV600E /NRASQ61K ) revealed that MQ is a dual inducer of endoplasmic reticulum (ER) and redox stress responses that precede MQ-induced loss of viability. ER-trackerTM DPX fluorescence imaging and electron microscopy indicated ER swelling, accompanied by rapid induction of ER stress signaling (phospho-eIF2α, XBP-1s, ATF4). Fluo-4 AM-fluorescence indicated the occurrence of cytosolic calcium overload observable within seconds of MQ exposure. In a bioluminescent murine model employing intracranial injection of A375-Luc2 (BRAFV600E /NRASQ61K ) cells, an oral MQ regimen efficiently antagonized brain tumor growth. Taken together, these data suggest that the clinical antimalarial MQ may be a valid candidate for drug repurposing aiming at chemotherapeutic elimination of malignant melanoma cells, even if metastasized to the brain and BRAFi-resistant.

Overcoming Therapy Resistance in Colon Cancer by Drug Repurposing

Simple Summary

Despite improvements in standardized screening methods and the development of promising therapies for colorectal cancer (CRC), survival rates are still low. Drug repurposing offers an affordable solution to achieve new indications for previously approved drugs that could play a protagonist or adjuvant role in the treatment of CRC. In this review, we summarize the current data supporting drug repurposing as a feasible option for patients with CRC.

Abstract

Colorectal cancer (CRC) is the third most common cancer in the world. Despite improvement in standardized screening methods and the development of promising therapies, the 5-year survival rates are as low as 10% in the metastatic setting. The increasing life expectancy of the general population, higher rates of obesity, poor diet, and comorbidities contribute to the increasing trends in incidence. Drug repurposing offers an affordable solution to achieve new indications for previously approved drugs that could play a protagonist or adjuvant role in the treatment of CRC with the advantage of treating underlying comorbidities and decreasing chemotherapy toxicity. This review elaborates on the current data that supports drug repurposing as a feasible option for patients with CRC with a focus on the evidence and mechanism of action promising repurposed candidates that are widely used, including but not limited to anti-malarial, anti-helminthic, anti-inflammatory, anti-hypertensive, anti-hyperlipidemic, and anti-diabetic agents.

Hotspot ESR1 Mutations Are Multimodal and Contextual Modulators of Breast Cancer Metastasis

Constitutively active estrogen receptor α (ER/ESR1) mutations have been identified in approximately one-third of ER+ metastatic breast cancers. Although these mutations are known as mediators of endocrine resistance, their potential role in promoting metastatic disease has not yet been mechanistically addressed. In this study, we show the presence of ESR1 mutations exclusively in distant but not local recurrences in five independent breast cancer cohorts. In concordance with transcriptomic profiling of ESR1-mutant tumors, genome-edited ESR1 Y537S and D538G-mutant cell models exhibited a reprogrammed cell adhesive gene network via alterations in desmosome/gap junction genes and the TIMP3/MMP axis, which functionally conferred enhanced cell-cell contacts while decreasing cell-extracellular matrix adhesion. In vivo studies showed ESR1-mutant cells were associated with larger multicellular circulating tumor cell (CTC) clusters with increased compactness compared with ESR1 wild-type CTCs. These preclinical findings translated to clinical observations, where CTC clusters were enriched in patients with ESR1-mutated metastatic breast cancer. Conversely, context-dependent migratory phenotypes revealed cotargeting of Wnt and ER as a vulnerability in a D538G cell model. Mechanistically, mutant ESR1 exhibited noncanonical regulation of several metastatic pathways, including secondary transcriptional regulation and de novo FOXA1-driven chromatin remodeling. Collectively, these data provide evidence for ESR1 mutation-modulated metastasis and suggest future therapeutic strategies for targeting ESR1-mutant breast cancer.

SIGNIFICANCE

Context- and allele-dependent transcriptome and cistrome reprogramming in mutant ESR1 cell models elicit diverse metastatic phenotypes related to cell adhesion and migration, which can be pharmacologically targeted in metastatic breast cancer.

Emerging drug targets for colon cancer: A preclinical assessment

INTRODUCTION

Colorectal cancer (CRC) is the second leading cause of cancer-related death in the United States. There have been improvements in screening, and therefore overall survival, but patients continue to present at late stages when minimal treatment options are available to them. While some targeted therapies have been introduced, their application is limited by patient-specific tumor characteristics. Additional targets for CRC in patients who present at a late stage, or who experience tumor relapse, need to be identified to continue to improve patient outcomes.

AREAS COVERED

This review focuses on emerging pathways and drug targets for the treatment of colorectal cancer. The shift to the cancer stem cell model and potential targets involving Wnt, NF-κB, phosphodiesterases, RAS, and guanylyl cyclase C, are discussed. The current utility of checkpoint inhibitors and evolving immunological options are examined.

EXPERT OPINION

Surgery and current systemic cytotoxic therapies are inadequate to appropriately treat the full spectrum of CRC, especially in those patients who present with metastatic or treatment-refractory disease. In addition to the identification of new, more generalizable targets, additional focus is being placed on novel administrations. Immuno-oncologic options and stem cell-targeting therapies for mCRC will become available to patients and may increase survival.

Alkaloid leonurine exerts anti-inflammatory effects via modulating MST1 expression in trophoblast cells

BACKGROUND

Pre-eclampsia (PE) is mainly attributed to the inflammation of trophoblast cells in pregnant women, which results in damage to the maternal organs and growth retardation of the fetus. Alkaloid leonurine (LNR) is a plant compound and has anti-inflammatory effects. Here we aimed to investigate the effects of LNR on human and mouse trophoblast cells and the underlying mechanisms.

METHODS

The levels of the inflammatory factors in trophoblast cells under lipopolysaccharides (LPS) stimulation were analyzed with ELISA. Western blot was employed to examine the protein expression. Trophoblast cells in Mammalian ste20-like kinase 1 (MST1-/- ) or wild type (WT) mice were isolated to examine the expression of signal molecules in the nuclear factor-κB (NF-κB) pathway. Concentration-dependent activity of NF-κB was examined. The regulation of LNR and MST1 in MST1-/- trophoblast cells was studied as well.

RESULTS

Our data showed that LNR exhibited anti-inflammatory effects and suppressed the NF-κB signaling by inhibiting LPS-induced inflammation in trophoblast cells. LNR upregulated the expression of MST1, and the anti-inflammatory role of LNR was greatly relieved in MST1-knockout trophoblast cells, although it displayed weak roles in NF-κB signaling.

CONCLUSION

LNR exhibits anti-inflammatory effects on human and mouse trophoblast cells by upregulating MST1 in the NF-κB signal pathway.

Dihydroartemisinin Suppresses the Tumorigenesis and Cycle Progression of Colorectal Cancer by Targeting CDK1/CCNB1/PLK1 Signaling

Dihydroartemisinin (DHA), a well-known antimalarial drug, has been widely investigated for its antitumor effects in multiple malignancies. However, its effects and regulatory mechanisms in colorectal cancer (CRC) are still unproved. In this study, in vitro experiments including CCK8, EdU, Transwell, and flow cytometry analyses and an in vivo tumorigenesis model were conducted to assess the effects of DHA on the bio-behaviors of CRC cells. Additionally, RNA-seq combined with gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses was used to obtain the targets of DHA, and these were verified by molecular docking, qRT-PCR, and Western blotting. As a result, we found that DHA significantly suppressed the proliferation, DNA synthesis, and invasive capabilities and induced cell apoptosis and cell cycle arrest in HCT116, DLD1, and RKO cells in vitro and in vivo. Further analyses indicated that the targets of DHA were predominantly enriched in cell cycle-associated pathways, including CDK1, CCNB1, and PLK1; and DHA could bind with the CDK1/CCNB1 complex and inhibit the activation of CDK1/CCNB1/PLK1 signaling. Moreover, cucurbitacin E, a specific inhibitor of the CDK1/CCNB1 axis, enhanced the inhibitory effects of DHA on DNA synthesis and colony formation in HCT116 and DLD1 cells. In short, DHA could suppress the tumorigenesis and cycle progression of CRC cells by targeting CDK1/CCNB1/PLK1 signaling.

Cellular targets of mefloquine

Mefloquine is a quinoline-based compound widely used as an antimalarial drug, particularly in chemoprophylaxis. Although decades of research have identified various aspects of mefloquine's anti-Plasmodium properties, toxic effects offset its robust use in humans. Mefloquine exerts harmful effects in several types of human cells by targeting many of the cellular lipids, proteins, and complexes, thereby blocking a number of downstream signaling cascades. In general, mefloquine modulates several cellular phenomena, such as alteration of membrane potential, induction of oxidative stress, imbalance of ion homeostasis, disruption of metabolism, failure of organelle function, etc., leading to cell cycle arrest and programmed cell death. This review aims to summarize the information on functional and mechanistic findings related to the cytotoxic effects of mefloquine.

Repurposing of Antimicrobial Agents for Cancer Therapy: What Do We Know?

The substantial costs of clinical trials, the lengthy timelines of new drug discovery and development, along the high attrition rates underscore the need for alternative strategies for finding quickly suitable therapeutics agents. Given that most approved drugs possess more than one target tightly linked to other diseases, it encourages promptly testing these drugs in patients. Over the past decades, this has led to considerable attention for drug repurposing, which relies on identifying new uses for approved or investigational drugs outside the scope of the original medical indication. The known safety of approved drugs minimizes the possibility of failure for adverse toxicology, making them attractive de-risked compounds for new applications with potentially lower overall development costs and shorter development timelines. This latter case is an exciting opportunity, specifically in oncology, due to increased resistance towards the current therapies. Indeed, a large body of evidence shows that a wealth of non-cancer drugs has beneficial effects against cancer. Interestingly, 335 drugs are currently being evaluated in different clinical trials for their potential activities against various cancers (Redo database). This review aims to provide an extensive discussion about the anti-cancer activities exerted by antimicrobial agents and presents information about their mechanism(s) of action and stage of development/evaluation.

Nuciferine Inhibits Skin Cutaneous Melanoma Cell Growth by Suppressing TLR4/NF-κB Signaling

BACKGROUND

Melanoma causes more than 80% of deaths from all dermatologic cancers. Hence, screening and identifying effective compounds to inhibit the growth of melanoma have crucial importance in basic and clinical treatment.

METHODS

High throughput screening was performed to screen and identify compounds that have anti-melanoma ability. Melanoma cell and mouse allograft models were used to examine the anti-tumor effects of Nuciferine (NCFR). Western blot, qPCR, and lentivirus overexpression were applied to detect the activation of the TLR4/NF-κB signaling pathway.

RESULTS

NCFR administration significantly suppressed melanoma cell growth and tumor size by inhibiting the phosphorylation of p65. NCFR treatment also could suppress TNF-α-induced activation of NF-κB signaling. The anti-tumor effect of NCFR might be mediated by targeting Toll-like receptors 4.

CONCLUSION

NCFR inhibits melanoma cell growth and suppresses tumor size, which provides potential therapeutic strategies for melanoma treatment.

Differential Stabilities of Mefloquine-Bound Human and Plasmodium falciparum Acyl-CoA-Binding Proteins

Toxic effects of pharmacological drugs restrict their robust application against human diseases. Although used as a drug in the combinatorial therapy to treat malaria, the use of mefloquine is not highly recommended because of its adverse effects in humans. Mefloquine inhibits the binding of acyl-CoAs to acyl-CoA-binding proteins of Plasmodium falciparum (PfACBPs) and human (hACBP). In this study, we have used molecular dynamics simulation and other computational approaches to investigate the differences of stabilities of mefloquine-PfACBP749 and mefloquine-hACBP complexes. The stability of mefloquine in the binding cavity of PfACBP749 is less than its stability in the binding pocket of hACBP. Although the essential tyrosine residues (tyrosine-30 and tyrosine-33 of PfACBP749 and tyrosine-29 and tyrosine-32 of hACBP) mediate the initial binding of mefloquine to the proteins by π-stacking interactions, additional temporally longer interactions between mefloquine and aspartate-22 and methionine-25 of hACBP result in stronger binding of mefloquine to hACBP. The higher fluctuation of mefloquine-binding residues of PfACBP749 contributes to the instability of mefloquine in the binding cavity of the protein. On the contrary, in the mefloquine-bound state, the stability of hACBP protein is less than the stability of PfACBP749. The helix-to-coil transition of the N-terminal hydrophobic region of hACBP has a destabilizing effect upon the protein's structure. This causes the induction of aggregation properties in the hACBP in the mefloquine-bound state. Taken together, we describe the mechanistic features that affect the differential dynamic stabilities of mefloquine-bound PfACBP749 and hACBP proteins.

Long non-coding RNA H19 regulates Bcl-2, Bax and phospholipid hydroperoxide glutathione peroxidase expression in spontaneous abortion

Spontaneous abortion (SA) is the most frequently occurring pregnancy disorder and is a serious threat to women's health. Identifying novel risk factors and the molecular mechanisms underlying SA are important. The present study reported that the RNA expression levels of long non-coding RNA H19 were lower in SA group compared with those in the control group, and the expression of Bax was increased and levels of Bcl-2 and phospholipid hydroperoxide glutathione peroxidase (GPX4) were decreased in SA group at both the mRNA and protein levels. H19 expression was positively correlated with Bcl-2 and GPX4 expression and negatively linked with Bax levels. It was demonstrated that silencing H19 downregulated Bcl-2 and GPX4 expression and upregulated Bax expression at both the mRNA and protein levels in HTR-8/SVneo trophoblast cells. In conclusion, the present findings suggested that H19 has important roles in SA by promoting apoptosis and ferroptosis.

Targeting tumor hypoxia and mitochondrial metabolism with anti-parasitic drugs to improve radiation response in high-grade gliomas

High-grade gliomas (HGGs), including glioblastoma and diffuse intrinsic pontine glioma, are amongst the most fatal brain tumors. These tumors are associated with a dismal prognosis with a median survival of less than 15 months. Radiotherapy has been the mainstay of treatment of HGGs for decades; however, pronounced radioresistance is the major obstacle towards the successful radiotherapy treatment. Herein, tumor hypoxia is identified as a significant contributor to the radioresistance of HGGs as oxygenation is critical for the effectiveness of radiotherapy. Hypoxia plays a fundamental role in the aggressive and resistant phenotype of all solid tumors, including HGGs, by upregulating hypoxia-inducible factors (HIFs) which stimulate vital enzymes responsible for cancer survival under hypoxic stress. Since current attempts to target tumor hypoxia focus on reducing oxygen demand of tumor cells by decreasing oxygen consumption rate (OCR), an attractive strategy to achieve this is by inhibiting mitochondrial oxidative phosphorylation, as it could decrease OCR, and increase oxygenation, and could therefore improve the radiation response in HGGs. This approach would also help in eradicating the radioresistant glioma stem cells (GSCs) as these predominantly rely on mitochondrial metabolism for survival. Here, we highlight the potential for repurposing anti-parasitic drugs to abolish tumor hypoxia and induce apoptosis of GSCs. Current literature provides compelling evidence that these drugs (atovaquone, ivermectin, proguanil, mefloquine, and quinacrine) could be effective against cancers by mechanisms including inhibition of mitochondrial metabolism and tumor hypoxia and inducing DNA damage. Therefore, combining these drugs with radiotherapy could potentially enhance the radiosensitivity of HGGs. The reported efficacy of these agents against glioblastomas and their ability to penetrate the blood-brain barrier provides further support towards promising results and clinical translation of these agents for HGGs treatment.

Gallic Acid Inhibits Bladder Cancer T24 Cell Progression Through Mitochondrial Dysfunction and PI3K/Akt/NF-κB Signaling Suppression

Gallic acid (GA), a hydrolyzable tannin, has a wide range of pharmacological activities. This study revealed that, GA significantly inhibited T24 cells viability in a concentration- and time- dependent manner. The IC₅₀ of GA stimulating T24 cells for 24, 48, and 72 h were 21.73, 18.62, and 11.59 µg/ml respectively, and the inhibition rate was significantly higher than the positive control drug selected for CCK-8 assay. Meanwhile, after GA treatment, the morphology of T24 cells were changed significantly. Moreover, GA significantly inhibited T24 cells proliferation and blocked T24 cells cycle in S phase (p < 0.001). GA induced T24 cells apoptosis (p < 0.001), accompanied by reactive oxygen species (ROS) accumulation and mitochondrial membrane potential (MMP) depolarization. Western blotting analysis showed that GA significantly increased Cleaved caspase-3, Bax, P53, and Cytochrome C (Cyt-c) proteins expression, and decreased Bcl-2, P-PI3K, P-Akt, P-IκBα, P-IKKα, and P-NF-κB p65 proteins expression in T24 cells (p < 0.05). Real-Time PCR results verified that GA significantly promoted Caspase-3, Bax, P53, and Cyt-c genes expression, and inhibited Bcl-2, PI3K, Akt, and NF-κB p65 genes expression (p < 0.001). However, on the basis of GA (IC₅₀) stimulation, NAC (an oxidative stress inhibitor) pretreatment reversed the apoptotic rate of T24 cells and the expression of Bax, Cleaved caspase-3, P53, Bcl-2 proteins, and the MMP level in T24 cells, as well as the expression of Cyt-c protein in T24 cells mitochondria and cytoplasm. In addition, GA significantly suppressed T24 cells migration and invasion ability with VEGF protein inhibition (p < 0.001). Briefly, GA can inhibit T24 cells proliferation, metastasis and promote apoptosis, and the pro-apoptotic activity is closely associated with mitochondrial dysfunction and PI3K/Akt/NF-κB signaling suppression. Our study will help in finding a safe and effective treatment for bladder cancer.

The anti-infection drug furazolidone inhibits NF-κB signaling and induces cell apoptosis in small cell lung cancer

Targeting nuclear factor kappa B (NF-κB) signaling pathway has become a promising strategy for the development of new antitumor drugs. In this paper, we found that anti-infection drug furazolidone (FZD) could significantly inhibit NF-κB-driven luciferase activity, and FZD could markedly inhibit both of the constitutive and tumor necrosis factor-α (TNFα)-triggered phosphorylation of NF-κB p65 in small cell lung cancer (SCLC). Further studies revealed that FZD inhibited the expression of inhibitor of kappa B kinase β (IKKβ) in SCLC cells. In addition, we found that FZD had significant antitumor activities in SCLC cells. FZD could markedly suppress the cell viability of SCLC cells dose-dependently, and FZD could significantly induce the cleavages of poly ADP-ribose polymerase (PARP) and Caspase3, the biomarkers of cell apoptosis, in SCLC cells. The flow cytometry also revealed that FZD induced cell apoptosis in SCLC cells. Finally, we also found that overexpression of constitutively activated IKKβ could significantly abolish FZD-induced cell growth inhibition in SCLC cells, which further confirmed that FZD displayed its anti-SCLC activity through regulating NF-κB signaling pathway.

Mefloquine Inhibits Esophageal Squamous Cell Carcinoma Tumor Growth by Inducing Mitochondrial Autophagy

Esophageal squamous cell carcinoma (ESCC) has a worldwide impact on human health, due to its high incidence and mortality. Therefore, identifying compounds to increase patients' survival rate is urgently needed. Mefloquine (MQ) is an FDA-approved anti-malarial drug, which has been reported to inhibit cellular proliferation in several cancers. However, the anti-tumor activities of the drug have not yet been completely defined. In this study, mass spectrometry was employed to profile proteome changes in ESCC cells after MQ treatment. Sub-cellular localization and gene ontology term enrichment analysis suggested that MQ treatment mainly affect mitochondria. The KEGG pathway enrichment map of down-regulated pathways and Venn diagram indicated that all of the top five down regulated signaling pathways contain four key mitochondrial proteins (succinate dehydrogenase complex subunit C (SDHC), succinate dehydrogenase complex subunit D, mitochondrially encoded cytochrome c oxidase III and NADH: ubiquinone oxidoreductase subunit V3). Meanwhile, mitochondrial autophagy was observed in MQ-treated KYSE150 cells. More importantly, patient-derived xenograft mouse models of ESCC with SDHC high expression were more sensitive to MQ treatment than low SDHC-expressing xenografts. Taken together, mefloquine inhibits ESCC tumor growth by inducing mitochondrial autophagy and SDHC plays a vital role in MQ-induced anti-tumor effect on ESCC.

Drug repurposing applied: Activity of the anti-malarial mefloquine against Echinococcus multilocularis

The current chemotherapeutical treatment against alveolar echinococcosis relies exclusively on benzimidazoles, which are not parasiticidal and can induce severe toxicity. There are no alternative treatment options. To identify novel drugs with activity against Echinococcus multilocularis metacestodes, researchers have studied potentially interesting drug targets (e.g. the parasite's energy metabolism), and/or adopted drug repurposing approaches by undertaking whole organism screenings. We here focus on drug screening approaches, which utilize an in vitro screening cascade that includes assessment of the drug-induced physical damage of metacestodes, the impact on metacestode viability and the viability of isolated parasite stem cells, structure-activity relationship (SAR) analysis of compound derivatives, and the mode of action. Finally, once in vitro data are indicative for a therapeutic window, the efficacy of selected compounds is assessed in experimentally infected mice. Using this screening cascade, we found that the anti-malarial mefloquine was active against E. multilocularis metacestodes in vitro and in vivo. To shed more light into the mode of action of mefloquine, SAR analysis on mefloquine analogues was performed. E. multilocularis ferritin was identified as a mefloquine-binding protein, but its precise role as a drug target remains to be elucidated. In mice that were infected either intraperitoneally with metacestodes or orally with eggs, oral treatment with mefloquine led to a significant reduction of parasite growth compared to the standard treatment with albendazole. However, mefloquine was not acting parasiticidally. Assessment of mefloquine plasma concentrations in treated mice showed that levels were reached which are close to serum concentrations that are achieved in humans during long-term malaria prophylaxis. Mefloquine might be applied in human AE patients as a salvage treatment. Future studies should focus on other repurposed anti-infective compounds (MMV665807, niclosamide, atovaquone), which showed stronger in vitro activity against E. multilocularis than mefloquine.

Overexpression of tripartite motif containing 26 inhibits non-small cell lung cancer cell growth by suppressing PI3K/AKT signaling

It has been reported that tripartite motif containing 26 (TRIM26) is involved in the tumorigenesis of some cancers, but its function in non-small cell lung cancer (NSCLC) is still unclear. In this study, we found that TRIM26 was markedly down-regulated in both of NSCLC tumor tissues and cell lines. Additionally, high expression of TRIM26 in NSCLC patients predicted a positive index for patients' overall survival. What is more, overexpression of TRIM26 significantly suppressed NSCLC cell growth. Our further studies indicated that overexpression of TRIM26 inhibited the phosphorylation of PI3K p85 and AKT. And overexpressed TRIM26 regulated cell cycle-related genes' expression, including downregulating CDK4, Cyclin A, Cyclin D1, Cyclin D3, and Cyclin E, and upregulating p27 expression. Finally, we found that TRIM26 up-regulated PTEN expression by stabilizing PTEN protein in NSCLC cells. Collectively, our present study indicated that TRIM26 was decreased in NSCLC and overexpression of TRIM26 inhibited NSCLC cell growth by suppressing PI3K/AKT pathway, which suggested that TRIM26 could be as a potential target for the treatment of NSCLC in the future.

Mefloquine binding to human acyl-CoA binding protein leads to redox stress-mediated apoptotic death of human neuroblastoma cells

Malaria is an infectious disease that is caused by different species of Plasmodium. Several antimalarial drugs are used to counter the spread and infectivity of Plasmodium species. However, humans are also vulnerable to many of the antimalarial drugs, including the quinoline-based drugs. In particular, the antimalarial mefloquine has been reported to show adverse neuropsychiatric effects in humans. Though mefloquine is known to be neurotoxic, the molecular mechanisms associated with this phenomenon are still obscure. In this study, we show that mefloquine binds to and inactivates the human acyl-CoA binding protein (hACBP), potentially inducing redox stress in human neuroblastoma cells (IMR-32). Mefloquine occupies the acyl-CoA binding pocket of hACBP by interacting with several of the critical acyl-CoA binding amino acids. This leads to the competitive inhibition of acyl-CoA(s) binding to hACBP and to the accumulation of lipid droplets inside the IMR-32 cells. The accumulation of cytosolic lipid globules and oxidative stress finally correlates with the apoptotic death of cells. Taken together, our study deciphers a mechanistic detail of how mefloquine leads to the death of human cells by perturbing the activity of hACBP and lipid homeostasis.

Inhibition of Ubiquitin Specific Protease 1 Sensitizes Colorectal Cancer Cells to DNA-Damaging Chemotherapeutics

Mutations and altered expression of deubiquitinating enzymes (DUBs) have been found associated with many human diseases including cancers. In this study, Ubiquitin specific protease 1 (USP1) expression was found significantly increased in some colorectal cancers (CRC). The elevated USP1 level was associated with short overall survival of patients and with advanced stages of cancers. In cultured CRC cells, knockdown of USP1 induced growth arrest at G₂/M of cell cycle and reduced the expression of anti-apoptotic proteins Bcl-2 and Mcl-1. Its knockdown also led to reduction of DNA-repair related substrates FANCD2 and ID1. Further investigations found that small molecular inhibitor of USP1 ML323 sensitized CRC cells to DNA-targeting chemotherapeutics, including doxorubicin, TOPI/II inhibitors, and PARP inhibitor, but not to 5-Fu. These results indicate that USP1 plays a critical in colorectal cancer cell survival and is a promising target for anti-colorectal cancer chemotherapy. Targeting USP1 may represent an effective strategy to regulate the DNA-repairing system.

Drug Repurposing in the Development of Anticancer Agents

BACKGROUND

Research into repositioning known drugs to treat cancer other than the originally intended disease continues to grow and develop, encouraged in part, by several recent success stories. Many of the studies in this article are geared towards repurposing generic drugs because additional clinical trials are relatively easy to perform and the drug safety profiles have previously been established.

OBJECTIVE

This review provides an overview of anticancer drug development strategies which is one of the important areas of drug restructuring.

METHODS

Repurposed drugs for cancer treatments are classified by their pharmacological effects. The successes and failures of important repurposed drugs as anticancer agents are evaluated in this review.

RESULTS AND CONCLUSION

Drugs could have many off-target effects, and can be intelligently repurposed if the off-target effects can be employed for therapeutic purposes. In cancer, due to the heterogeneity of the disease, often targets are quite diverse, hence a number of already known drugs that interfere with these targets could be deployed or repurposed with appropriate research and development.

Molecular Mechanism of Matrine from Sophora alopecuroides in the Reversing Effect of Multi-Anticancer Drug Resistance in K562/ADR Cells

Multidrug resistance is the main obstacle to current chemotherapies. In this study, we evaluated the reversing effect of matrine, the principal alkaloid derived from Sophora alopecuroides, on chemoresistant leukemia K562/ADR cells. Matrine in a range of the nontoxic concentration was employed in the whole study. IC₅₀s of cancer medicines were tested using WST-8 assay. Drug export and apoptotic rates were examined using flow cytometry. The mRNA and protein expressions were quantified by quantitative real-time PCR and western blotting, respectively. Our data indicated that matrine had potent reversal properties augmenting cytotoxicity of cancer medicines on K562/ADR cells as well as apoptotic rates induced by doxorubicin. Moreover, matrine inhibited drug-exporting activity and expression of ATP-binding cassette subfamily B member 1 (ABCB1) on both mRNA and protein levels. That might result from inhibited NF-kappa B activation, which also led to restored intrinsic apoptosis. These findings suggest that matrine in the nontoxic concentration can suppress ABCB1 drug transport and facilitate the intrinsic apoptosis pathway through the inhibiting effect on NF-kappa B and has the potential to become an efficient sensitizer for anticancer drug resistance.

Drug Repurposing for Retinoblastoma: Recent Advances

Retinoblastoma is the intraocular malignancy that occurs during early childhood. The current standard of care includes chemotherapy followed by focal consolidative therapies, and enucleation. Unfortunately, these are associated with many side and late effects. New drugs and/or drug combinations need to be developed for safe and effective treatment. This compelling need stimulated efforts to explore drug repurposing for retinoblastoma. While conventional drug development is a lengthy and expensive process, drug repurposing is a faster, alternate approach, where an existing drug, not meant for treating cancer, can be repurposed to treat retinoblastoma. The present article reviews various attempts to test drugs approved for different purposes such as calcium channels blockers, non-steroidal antiinflammatory drugs, cardenolides, antidiabetic, antibiotics and antimalarial for treating retinoblastoma. It also discusses other promising candidates that could be explored for repurposing for retinoblastoma.

Ubiquitin-specific protease 44 inhibits cell growth by suppressing AKT signaling in non-small cell lung cancer

Ubiquitin-specific protease 44 (USP44) has been reported as a tumor suppressor or promoter in some tumors, but its function in non-small cell lung cancer (NSCLC) is still unclear. In this study, USP44 was found significantly downregulated in both of NSCLC tissues and cell lines, and low expression of USP44 predicted a poor prognosis for NSCLC patients. Overexpression of USP44 markedly downregulated the expression levels of Cyclin D1 and CDK4, but upregulated p53 expression, as a result of which, suppressing the cell growth of NSCLC cells. Further studies indicated that overexpression of USP44 significantly inhibited the phosphorylation of AKT, and its down-stream signals, including mTOR and P70S6K. Moreover, overexpression of USP44 increased PTEN protein but not its mRNA levels, which suggested that USP44 inhibited AKT signaling by stabilizing PTEN in NSCLC cells. In conclusion, we demonstrated that USP44 showed prior evidence of a tumor suppressive function in NSCLC cells, and inhibited NSCLC cell growth by suppressing AKT signaling, suggesting that USP44 could be as a novel target for NSCLC therapy.

The natural flavonoid glycoside vitexin displays preclinical antitumor activity by suppressing NF-κB signaling in nasopharyngeal carcinoma

Background and objectives: Vitexin is a natural flavonoid glycoside mainly extracted from the leaves of vitex, which has a variety of physiological activities. For example, vitexin has antitumor and anti-inflammation activities, and it can also promote blood circulation in the body. However, the function and mechanism of vitexin in nasopharyngeal carcinoma (NPC) are still unclear.

Materials and methods: Cell Counting Kit-8 assay and cell cycle analysis were performed to examine cell survival in response to vitexin. Immunoblotting was used to analyze relative proteins’ expression. NPC xenograft models were established to assess the effect of vitexin in vivo. The luciferase activity of pNFκB-Luc was analyzed by using Dual-Luciferase Reporter Assay System. Quantitative real-time polymerase chain reaction was performed to detect relative genes’ expression. Kinase activity of IKKβ was analyzed in a cell-free system.

Results: In this study, vitexin was found to display significant antitumor activity in NPC in vitro and in vivo. In NPC cells, vitexin inhibited cell cycle progression in NPC cells and induced the cleavages of PARP and inhibited antiapoptotic proteins’ expression, including Bcl-2 and Mcl1. Further studies indicated that vitexin significantly suppressed the luciferase activity of pNF-κB-Luc and inhibited the activation of NF-κB key regulators, including p65, IκBα and IKKs in NPC cells. Moreover, the kinase activity of IKKβ could be suppressed by vitexin in a cell-free system, and overexpression of CA-IKKβ could attenuate the inhibitory effect of vitexin on p65 phosphorylation.

Conclusion: These results indicated that vitexin displayed antitumor activity by suppressing NF-κB signaling in NPC, which suggested that vitexin could be as a potential drug for the treatment of NPC in the future.

Ubiquitin specific peptidase 5 regulates colorectal cancer cell growth by stabilizing Tu translation elongation factor

Ubiquitin specific peptidase 5 (USP5) is a ubiquitous expressed deubiquitinating enzyme (DUB). It has been shown involved in DNA repair, apoptosis, inflammation, and tumor cell growth. However, the function and molecular mechanism of USP5 in colorectal cancer (CRC) are still unclear. In the present study, we asked how it affected the growth of colorectal cancer cells.

Methods: A shRNA-based high-content screening was performed to identify DUBs affecting the growth of CRC cells. CCK-8 assay and xenografts were used to assess CRC cell growth, survival and tumorigenesis. RT-qPCR, immunoblotting and immunohistochemistry were carried out to quantitate USP5 expression in CRC tissues and cell lines. Immunoprecipitation and mass spectrometry analysis were performed to identify USP5-interacting proteins. Cycloheximide chase was performed to assess Tu translation elongation factor (TUFM) stability. Dual luciferase reporter assay was utilized for USP5 promoter analysis.

Results: We found that USP5 was highly expressed in a group of primary CRC tissues, and the increased USP5 was correlated with clinical stages and shorter overall survival. While USP5 knockdown effectively inhibited CRC cell growth, overexpressed USP5 promoted the growth of CRC cells and made them more resistant to doxorubicin (DOX). TUFM was discovered as a substrate of USP5. USP5 deubiquitinated TUFM and increased its level in CRC cells. Enforced expression of TUFM was able to alleviate the growth inhibition induced by USP5 knockdown. Further analyses showed that EBF transcription factor 1 (EBF1) was a major regulator for USP5 transcription, and DOX inhibited EBF1-USP5-TUFM axis in CRC cells.

Conclusions: USP5 was required for CRC cells and promoted their growth and resistance to chemotherapeutics. TUFM was a USP5 deubiquitinating substrate that mediated the cellular effects of USP5. The transcription of USP5 was regulated by EBF1. Thus, targeting EBF1-USP5-TUFM axis is a potential novel strategy for CRC treatment.

Ubiquitin specific peptidase 49 inhibits non-small cell lung cancer cell growth by suppressing PI3K/AKT signaling

Ubiquitin specific peptidase 49 (USP49) has been reported as a tumor suppressor in several tumors, but its function and molecular mechanism in non-small cell lung cancer (NSCLC) are still unknown. In this study, USP49 was found downregulated in NSCLC primary tissues and cell lines, and high USP49 predicted a positive index for the overall survival of NSCLC patients. Overexpression of USP49 downregulated the expression levels of Cyclin D1, and upregulated p53 expression. Further flow cytometry analysis showed that overexpressed USP49 induced cell cycle arrest at G0/G1 phase. As a result, overexpression of USP49 significantly inhibited cell growth of NSCLC cells. In mechanism, overexpression of USP49 inhibited PI3K/AKT signaling, but knockdown of USP49 enhanced this signaling. Further studies indicated that USP49 deubiquitinated PTEN and stabilized PTEN protein, which suggested that USP49 inhibited PI3K/AKT signaling by stabilizing PTEN in NSCLC cells. In conclusion, we demonstrated that USP49 was functional in NSCLC cells, and inhibited NSCLC cell growth by suppressing PI3K/AKT signaling, suggesting that USP49 could be as a novel target for NSCLC therapy.

Overexpression of CMTM7 inhibits cell growth and migration in liver cancer

Chemokine-like factor (CKLF)-like, MAL and related proteins for vesicle trafficking and membrane link (MARVEL) transmembrane domain-containing family proteins (CMTMs) have significant roles in the immune system, in male reproduction, as well as in tumorigenesis. Previous studies have shown that CMTM family member 7 (CMTM7) was broadly expressed in various normal tissues, but not in lung, gastric, esophageal, pancreas, and cervix cancers. To explore its relationship with liver cancer, we examined the expression of CMTM7 in liver cancers and its correlation with clinical and pathological conditions. We found that CMTM7 expression was markedly reduced in liver cancer tissues, and negatively correlated with TNM staging and tumor metastasis. In vitro studies showed that enforced expression of CMTM7 inhibited the cell growth and migration of liver cancer cells. Further analysis revealed that CMTM7 suppressed AKT signaling and induced cell cycle arrest at the G0/G1 phase in the liver cancer cells, likely as the consequent of decreased levels of cyclin D1, cyclin-dependent kinase 4 (CDK4), and CDK6, and increased p27 expression. Thus, CMTM7 functions as a tumor suppressor in liver cancer through suppressing cell cycle progression.

MicroRNA-26a inhibits multiple myeloma cell growth by suppressing cyclin-dependent kinase 6 expression

MicroRNA-26a (miR-26a) has been reported to be involved in the tumorigenesis of several tumors, but its biological function and molecular mechanism in multiple myeloma (MM) are still unknown. In this study, we found that overexpression of miR-26a obviously inhibited MM cell growth, and delayed tumor growth in xenografts. Further studies showed that overexpression of miR-26a induced cell cycle arrest at G0/G1 phase in MM cells. MiR-26a mimic down-regulated the expression levels of CDK6 and E2F1, but up-regulated p53 and p21 expression. In contrast, overexpression of CDK6 decreased the effect of miR-26a mimic on MM cell survival. Moreover, miR-26a targeted CDK6 mRNA and thus suppressed CDK6 protein expression. Overexpression of miR-26a also enhanced the cytotoxic action of doxorubicin against MM. These results demonstrated that miR-26a was involved in the development of MM through regulating CDK6 signaling pathway, and indicated that miR-26a could be as a novel target for anti-tumor therapy in clinic as a single strategy or in combination with other anti-tumor drugs in MM.

MicroRNA-590-5p antagonizes the inhibitory effect of high glucose on osteoblast differentiation by suppressing Smad7 in MC3T3-E1 cells

Objective

MicroRNA-590-5p (miR-590-5p) has been reported to stimulate osteoblast differentiation; however, its effect in diabetic osteoporosis remains unknown. This study investigated the effect of miR-590-5p on high glucose (HG)-suppressed osteoblast differentiation.

Methods

The effect of HG on MC3T3-E1 cell survival was assessed using the MTT assay. The expression levels and activities of osteoblastic proteins were evaluated by quantitative reverse transcription polymerase chain reaction (qRT-PCR), alkaline phosphatase (ALP) assay, and immunoblotting assay. Tumor growth factor-β (TGF-β) signaling in MC3T3-E1 cells was assessed using luciferase assay, qRT-PCR, and immunoblotting. Mineralized nodule formation in MC3T3-E1 cells was examined by using the mineralization assay.

Results

When MC3T3-E1 cells were exposed to HG conditions, there was significant downregulation of miR-590-5p and osteoblastic proteins (e.g., collagen I, Runx2, and ALP); in contrast, Smad7 was upregulated. Furthermore, miR-590-5p targeted Smad7 and inhibited its expression. Additionally, overexpression of miR-590-5p significantly promoted osteoblast growth and differentiation by upregulating TGF-β signaling in HG-treated MC3T3-E1 cells.

Conclusions

Collectively, the results showed that miR-590-5p was involved in osteogenesis; moreover, miR-590-5p may represent a potential target for the treatment of diabetic osteoporosis.

Ubiquitin-specific peptidase 28 enhances STAT3 signaling and promotes cell growth in non-small-cell lung cancer

BACKGROUND AND OBJECTIVES

Ubiquitin-specific peptidase 28 (USP28) has been reported to play significant roles in several tumors, but its roles in non-small-cell lung cancer (NSCLC) is still unknown. In this study, we aimed to investigate the biological function and molecular mechanisms of USP28 in NSCLC.

MATERIALS AND METHODS

Immunoblotting analysis was used to detect relative proteins' expression. Luciferase assay was performed to explore the activation of signal transducer and activator of transcription 3 (STAT3). Immunoprecipitation was performed to assess whether USP28 interacted with STAT3 or deubiquitinated STAT3. Quantitative real-time PCR was performed to evaluate the relative mRNA levels of STAT3 and USP28. Cycloheximide chase assay was carried out to examine whether USP28 affected the half-life of STAT3 protein. Cell Counting Kit-8 assay and xenograft model were used to assess whether USP28 regulated NSCLC cell growth.

RESULTS

In this study, the deubiquitinating enzyme USP28 was found to mediate STAT3 signaling in NSCLC cells. USP28 interacted with STAT3, and increased the stability of STAT3 by inducing its deubiquitination. Further studies showed that USP28 was upregulated in both the primary tissues and cell lines of NSCLC. The Kaplan-Meier plotter also indicated that USP28 predicted a poor prognosis of NSCLC patients. Moreover, knockdown of USP28 inhibited cell growth of NSCLC cells in vitro and delayed NSCLC tumor growth in vivo.

CONCLUSION

These results demonstrated that USP28 was functional in NSCLC cells, and promoted NSCLC cell growth by inducing STAT3 signaling. This suggests that USP28 could be a novel target for NSCLC therapy.

The anthelmintic agent oxfendazole inhibits cell growth in non‑small cell lung cancer by suppressing c‑Src activation

The c‑Src protein family of tyrosine kinases are important in the tumorigenesis of many types of tumors, and may be a potential target for antitumor drug discovery. In the present study, immunoblotting was performed to analyze protein expression, CCK‑8 assay was carried out to assess cell viability and cell cycle was analyzed using a flow cytometer. The anthelmintic agent oxfendazole was observed to be a novel c‑Src inhibitor that blocked the activation of c‑Src. Oxfendazole also suppressed the cell growth of non‑small cell lung cancer (NSCLC) cells, and overexpression of c‑Src decreased the cytotoxicity of oxfendazole against NSCLC cells. In addition, oxfendazole induced cell cycle arrest at the G0/G1 phase, and downregulated the protein levels of Cyclin‑dependent kinase (CDK)‑4, CDK6, retinoblastoma protein and E2 transcription factor 1, and upregulated the expression levels of p53 and p21 in NSCLC cells. Furthermore, oxfendazole enhanced the cytotoxicity of cisplatin against NSCLC cells. These results demonstrated that oxfendazole exerted its antitumor activity by suppressing c‑Src signaling, and it was also indicated that the anthelmintic agent oxfendazole may be effective for anti‑NSCLC therapy in the clinic as a single agent or in combination with other antitumor drugs.

The anthelmintic drug flubendazole induces cell apoptosis and inhibits NF-κB signaling in esophageal squamous cell carcinoma

BACKGROUND AND OBJECTIVES

The nuclear factor kappa B (NF-κB) signaling is activated in esophageal squamous cell carcinoma (ESCC) and can be used as a potential target for anti-ESCC drug discovery. In this study, we aimed to investigate the function of flubendazole as a novel NF-κB inhibitor in ESCC cells.

MATERIALS AND METHODS

Cell Counting Kit-8 assay was carried out to assess cell viability of ESCC cells. Flow cytometry and immunoblotting were performed to examine cell apoptosis. Immunoblotting assay was used to analyze the protein expression of NF-κB signaling. Luciferase assay was performed to explore the activation of NF-κB. Plasmids were transfected into ESCC cells using Lipofectamine® 2000.

RESULTS

In this study, the anthelmintic drug flubendazole was found to inhibit the activation of IκBα kinases (IKKs), block the activation of IκBα, and decrease the phosphorylation of NF-κB p65, which could be a novel NF-κB inhibitor in ESCC cells. We also found that flubendazole inhibited the cell survival of different ESCC cells and induced cell apoptosis in both EC9706 and TE1 cells. Moreover, overexpression of constitutively activated IKKβ markedly decreased the cytotoxic effect of flubendazole on EC9706 and TE1 cells. In addition, flubendazole also showed a synergistic effect on ESCC cells when combined with doxorubicin.

CONCLUSION

The results above demonstrated that flubendazole showed its anti-tumor action by suppressing the NF-κB signaling pathway and suggested that flubendazole might be re-purposed for anti-ESCC therapy in clinic as a single agent or in combination with other anti-tumor drugs.

The natural polyphenol curcumin induces apoptosis by suppressing STAT3 signaling in esophageal squamous cell carcinoma

Background

We and others have previously shown that the STAT3 signaling pathway is activated in some esophageal squamous cell carcinoma (ESCC) cells and is required for the survival and growth of these primary ESCC-derived xenografts. It has also been shown that the natural polyphenol curcumin is an effective anti-tumor agent.

Methods

Luciferase assay and immunoblotting were performed to examine whether curcumin suppressed STAT3 signaling. CCK-8 assay and xenografts were utilized for analyzing ESCC cell growth in culture and mice. Soft agar assay was carried out to determine the colony formation ability of ESCC cells in the presence or absence of curcumin. Cell death and cell cycle were assessed by In CELL Analyzer 2000. Immunohistochemistry and TUNEL assay were used for detecting apoptosis in ESCC tisuses. Molecular docking was performed to evaluate the interaction of curcumin with JAK2. JAK2 activity was assessed using an in vitro cell-free system. HE staining was used to evaluate the ESCC tissues.

Results

The natural polyphenol curcumin inhibited STAT3 phosphorylation rapidly and blocked STAT3-mediated signaling in ESCC cells. It also induced growth arrest and apoptosis in cultured ESCC cells, which were attenuated by enforced expression of STAT3. Furthermore, curcumin preferentially blocked the growth of primary ESCC-derived xenografts that harbored activated STAT3.

Conclusions

Curcumin is able to exert anti-tumor action through inhibiting the STAT3 signaling pathway. Giving its wide use in traditional medicines with low toxicity and few adverse reactions, it is conceivable that curcumin might be further explored as a unique STAT3 inhibitor for anti-cancer therapies.

Knockdown of RNF6 inhibits gastric cancer cell growth by suppressing STAT3 signaling

Background and objective

RNF6, an E3 ligase, has been reported to play an important role in the tumorigenesis in several tissues, but its role in gastric cancer is still unknown. In this study, we aimed to investigate the biological function and molecular mechanisms of RNF6 in gastric cancer.

Materials and methods

The expression levels of RNF6 were detected by quantitative real-time PCR (qRT-PCR) and immunoblotting in gastric cancer tissues and cell lines. Cell Counting Kit-8 assay was performed to evaluate cell proliferation. Cell apoptosis was analyzed by flow cytometer and immunoblotting. Luciferase assay, immunoblotting and qRT-PCR were performed to explore the activation of STAT3. Immunoprecipitation was performed to evaluate the ubiquitination of SHP-1.

Results

In this study, RNF6 was found to be upregulated in both primary tissues and cell lines of gastric cancer. Knockdown or overexpression of RNF6 inhibited or promoted cell growth of gastric cancer cells. Knockdown of RNF6 also induced the cleavage of PARP and promoted cell apoptosis in gastric cancer cells. In addition, knockdown of RNF6 also increased the cytotoxicity of doxorubicin against gastric cancer. Moreover, knockdown of RNF6 inhibited STAT3-derived luciferase activity and downregulated the phosphorylation of STAT3, but upregulated the protein level of SHP-1. Knockdown of RNF6 downregulated the expression of MCL1 and XIAP, which are target genes of STAT3. Further studies showed that RNF6 regulated the stability of SHP-1 by inducing its polyubiquitination.

Conclusion

These results demonstrated that RNF6 was highly expressed in gastric cancer and regulated the growth of gastric cancer cells by affecting SHP-1/STAT3 signaling, which suggested that RNF6 could be a novel target for gastric cancer therapy.

RING finger protein 38 induces gastric cancer cell growth by decreasing the stability of the protein tyrosine phosphatase SHP-1

The function of the E3 ligase RNF38 is still unknown in gastric cancer. Here, we found that RNF38 is upregulated in gastric cancer, and it is associated with the overall survival of gastric cancer patients. Further studies showed that RNF38 interacts with the nonreceptor tyrosine phosphatase SH2-containing protein tyrosine phosphatase 1 (SHP-1) and induces the polyubiquitination of SHP-1, which leads to destabilization of SHP-1 and promotion of STAT3 signaling in gastric cancer cells. In addition, overexpression or knockdown of RNF38 induces or suppresses gastric cancer cell growth in vitro, respectively, and silencing RNF38 delays tumor growth in vivo. These findings demonstrate that RNF38 is functional in gastric cancer and promotes STAT3 signaling by destabilizing SHP-1; thus, RNF38 could be a novel target for gastric cancer therapy.

Antimalarial drug mefloquine inhibits nuclear factor kappa B signaling and induces apoptosis in colorectal cancer cells

Nuclear factor kappa B (NF‐κB) signaling pathway is activated in many colorectal cancer (CRC) cells and in the tumor microenvironment, which plays a critical role in cancer initiation, development, and response to therapies. In the present study, we found that the widely used antimalarial drug mefloquine was a NF‐κB inhibitor that blocked the activation of IκBα kinase, leading to reduction of IκBα degradation, decrease of p65 phosphorylation, and suppressed expression of NF‐κB target genes in CRC cells. We also found that mefloquine induced growth arrest and apoptosis of CRC cells harboring phosphorylated p65 in culture and in mice. Furthermore, expression of constitutive active IKKβ kinase significantly attenuated the cytotoxic effect of the compound. These results showed that mefloquine could exert antitumor action through inhibiting the NF‐κB signaling pathway, and indicated that the antimalarial drug might be repurposed for anti‐CRC therapy in the clinic as a single agent or in combination with other anticancer drugs.