Wnt/β-catenin pathway regulates MGMT gene expression in cancer and inhibition of Wnt signalling prevents chemoresistance

Natural small molecule thymoquinone increases the chemosensitivity of glioblastoma to temozolomide through inhibiting Wnt/β-catenin signaling pathway to downregulate MGMT expression: In vitro and in vivo validation

Temozolomide (TMZ) is the only one oral first-line chemotherapeutic drug for glioblastoma treatment. However, O6-methylguanine-DNA methyltransferase (MGMT) can repair the lethal O6-methylguaine (O6-MeG) lesion produced by TMZ, thus imparting resistance to TMZ. Currently, the clinical utility of small molecule covalent MGMT inhibitors is limited by the occurrence of severe hematological toxicity. Therefore, developing new strategies for overcoming MGMT-mediated resistance is highly urgent. Here, we explored the feasibility that modulating Wnt/β-catenin signaling pathway in glioblastoma to inhibit MGMT expression to overcome TMZ resistance. From eight natural products or approved drugs with inhibitory effects on Wnt/β-catenin pathway, we found thymoquinone (TQ) completely suppressed MGMT expression in glioblastoma SF763 and SF767 cell lines within 24 h. As expected, TQ exhibited synergistic killing effects with TMZ in SF763 and SF767 cells, while in MGMT-negative SF126 cells only additive effect observed. Moreover, TQ remarkably enhanced the inhibition of TMZ on cell proliferation, clone formation, invasion and migration, and promoted cell apoptosis. In resistant SF763 mice tumor xenograft model, TQ significantly increased the suppression of TMZ on tumor growth, meanwhile maintaining good biosafety. Western blotting analysis indicated that TQ significantly inhibited the nuclear translocation of β-catenin and the expression of downstream proteins Cyclin D1 and MGMT. The addition of Wnt activator LiCl reversed the nuclear translocation of β-catenin and the expression of Cyclin D1 and MGMT induced by TQ. For the first time, our findings indicate that TQ can considerably increase the sensitivity of glioblastoma to TMZ by interfering Wnt/β-catenin pathway to downregulate MGMT expression.

Discovery of a novel Wnt inhibitor DK419: Reversing temozolomide resistance in glioblastoma by switching off Wnt/β-catenin signaling pathway to inhibit MGMT expression

Temozolomide (TMZ) remains the primary oral chemotherapeutic agent for glioblastoma, but its efficacy is hampered by resistance mechanisms involving O6-methylguanine-DNA methyltransferase (MGMT). MGMT repairs the TMZ-induced lethal O6-methylguanine (O6-MeG) lesions, leading to treatment resistance. Current small molecule covalent MGMT inhibitors have limited clinical application due to severe hematological toxicity when used with TMZ. Therefore, alternative strategies to overcome MGMT-mediated resistance are critically needed. Targeting the Wnt/β-catenin signaling pathway to suppress MGMT expression presents a promising approach. We synthesized and discovered that a novel Wnt inhibitor, DK419 (6-chloro-2-(trifluoromethyl)-N-(4-(trifluoromethyl)phenyl)-1H -benzimidazole-4-carboxamide), effectively suppressed MGMT expression within 12 h in TMZ-resistant SF763 and SF767 cell lines. DK419 demonstrated synergistic cytotoxic effects with TMZ in these cell lines, while only an additive effect was observed in MGMT-negative SF126 cells. Furthermore, DK419 significantly enhanced TMZ's inhibitory effects on cell proliferation, colony formation, invasion, and migration, while also promoting apoptosis. In a resistant mouse tumor xenograft model, DK419 significantly boosted TMZ's tumor growth suppression, maintaining good biosafety. Western blot analysis revealed that DK419 markedly inhibited the nuclear translocation of β-catenin and decreased the expression of its downstream targets, Cyclin D1 and MGMT. The addition of the Wnt activator LiCl reversed DK419-induced effects on β-catenin nuclear translocation and Cyclin D1 and MGMT expression. For the first time, our findings demonstrate that DK419 can significantly enhance glioblastoma sensitivity to TMZ by modulating the Wnt/β-catenin pathway to downregulate MGMT expression.

Glioma-astrocyte connexin43 confers temozolomide resistance through activation of the E2F1/ERCC1 axis

BACKGROUND

Glioma is the most prevalent and lethal tumor of the central nervous system. Routine treatment with temozolomide (TMZ) would unfortunately result in inevitable recurrence and therapy resistance, severely limiting therapeutic efficacy. Tumor-associated astrocytes (TAAs) are key components of the tumor microenvironment and increasing evidence has demonstrated that aberrant expression of connexin43 (Cx43) was closely associated with glioma progression and TMZ resistance. However, the specific role of Cx43 in mediating TMZ resistance through glioma and astrocyte interactions has not been fully explored.

METHODS

The expression and prognostic value of Cx43 were evaluated in tumor samples and clinical databases. ShRNA-medicated knockdown and Gfap-Cre Cx43flox/flox gene mouse were used to assess the role and functional significance of Cx43 in vitro and in vivo. Moreover, we performed mass spectrometry analysis, chromatin immunoprecipitation, and other biochemical assays to define the molecular mechanisms by which Cx43 promotes TMZ resistance.

RESULTS

We confirmed that the upregulation of Cx43 expression between TAAs and glioma cells contributed to TMZ resistance and tumor recurrence. Genetic knockdown or pharmacological inhibition of Cx43 enhanced TMZ-induced cytotoxicity. Mechanistically, elevated Cx43 expression induced β-catenin accumulation at the cell surface of glioma cells, suppressing T-cell factor/lymphoid enhancer-binding factor transcription. This led to impaired miR-205-5p expression and subsequent activation of the E2F1/ERCC1 axis, which eventually led to chemoresistance.

CONCLUSIONS

Our study reveals a novel regulatory mechanism in which the Cx43/miR-205-5p/E2F1/ERCC1 axis contributes to TMZ resistance in glioma. These findings further highlight the potential of targeting Cx43 as a therapeutic strategy in glioma.

Nanoparticle-based drug delivery systems to modulate tumor immune response for glioblastoma treatment

Glioblastoma (GBM) is a primary central nervous system neoplasm, characterized by a grim prognosis and low survival rates. This unfavorable therapeutic outcome is partially attributed to the inadequate immune infiltration and an immunosuppressive microenvironment, which compromises the effectiveness of conventional radiotherapy and chemotherapy. To this end, precise modulation of cellular dynamics in the immune system has emerged as a promising approach for therapeutic intervention. The advent of nanoparticle-based therapies has revolutionized cancer treatment and provided highly effective options. Consequently, various strategically designed nano-delivery platforms have been established to promote the efficacy of immune therapy against GBM. This review delves into the recent advancements in nano-based delivery systems that are designed to modulate immune cells in GBM microenvironment, and explores their multifaceted mechanisms, including the blockade of immune checkpoints, the restraint of immunosuppressive cells, the coordination of tumor-associated macrophages, the activation of innate immune cells, and the stimulation of adaptive immunity. Collectively, this summary not only advances the comprehension involved in modulating antitumor immune responses in GBM, but also paves the way for the development of innovative therapeutic strategies to conquer GBM. STATEMENT OF SIGNIFICANCE: Glioblastoma (GBM) is the most lethal brain tumor, with a median survival rate of merely 12-16 months after diagnosis. Despite surgical, radiation and chemotherapy treatments, the two-year survival rate for GBM patients is less than 10 %. The treatment of GBM is challenging mainly because several issues associated with the GBM microenvironment have not yet been resolved. Most recently, novel drug delivery approaches, based on the clear understanding of the intrinsic properties of GBM, have shown promise in overcoming some of the obstacles. In particular, taking account of the highly immunosuppressive tumor microenvironment in GBM, recent advancements in nano-based delivery systems are put forward to stimulate immune cells in GBM and unravel their multifaceted mechanisms. This review summarizes the latest nanoparticle-based drug delivery systems to modulate tumor immune response for glioblastoma treatment. Moreover, the development trends and challenges of nanoparticle-based drug delivery systems in modulating the immunity of GBM are predicted, which may facilitate widespread regimens springing up for successfully treating GBM.

Wnt-Regulated Therapeutics for Blood-Brain Barrier Modulation and Cancer Therapy

The Wnt signaling pathway has a significant regulatory part in tissue development and homeostasis. Dysregulation of the Wnt signaling pathway has been associated with many diseases including cancers and various brain diseases, making this signaling pathway a promising therapeutic target for these diseases. In this review, we describe the roles of the Wnt signaling pathway in the blood-brain barrier (BBB) in intracranial tumors and peripheral tumors, from preclinical and clinical perspectives, introduce Wnt-regulated therapeutics including various types of drugs and nanomedicines as BBB modulators for brain-oriented drug delivery and as therapeutic drugs for cancer treatments, and finally discuss limitations and future perspectives for Wnt-regulated therapeutics.

Overview of Wnt/β-Catenin Pathway and DNA Damage/Repair in Cancer

The Wnt/β-catenin pathway takes part in important cellular processes in tumor cells, such as gene expression, adhesion, and survival. The canonical pathway is activated in several tumors, and β-catenin is its major effector. The union of Wnt to the co-receptor complex causes the inhibition of GSK3β activity, thus preventing the phosphorylation and degradation of β-catenin, which accumulates in the cytoplasm, to subsequently be transported to the nucleus to associate with transcription factors. The relationship between Wnt/β-catenin and DNA damage/repair mechanisms has been a focus for the last few years. Studying the Wnt/β-catenin network interactions with DNA damage/repair proteins has become a successful research field. This review provides an overview of the participation of Wnt/β-catenin in DNA damage/repair mechanisms and their future implications as targets for cancer therapy.

NF-κB pathway and angiogenesis: insights into colorectal cancer development and therapeutic targets

Colorectal cancer (CRC) is currently ranked as the third most common type of cancer, contributing significantly to mortality and morbidity worldwide. Epigenetic and genetic changes occurred during CRC progression resulted in the cell proliferation, cancer progression, angiogenesis, and invasion. Angiogenesis is one of the crucial steps during cancer progression required for the delivery of essential nutrients to cancer cells and removes metabolic waste. During angiogenesis, different molecules are secreted from tumoral cells to trigger vascular formation including epidermal growth factor and the vascular endothelial growth factor (VEGF). The production and regulation of the secretion of these molecules are modulated by different subcellular pathways such as NF-κB. NF-κB is involved in regulation of different homeostatic pathways including apoptosis, cell proliferation, inflammation, differentiation, tumor migration, and angiogenesis. Investigation of different aspects of this pathway and its role in angiogenesis could provide a comprehensive overview about the underlying mechanisms and could be used for development of further therapeutic targets. In this review of literature, we comprehensively reviewed the current understanding and potential of NF-κB-related angiogenesis in CRC. Moreover, we explored the treatments that are based on the NF-κB pathway.

LAT4 drives temozolomide induced radiotherapy resistance in glioblastoma by enhancing mTOR pathway activation

BACKGROUND

Glioblastoma multiforme (GBM) represents the most prevalent form of primary malignant tumor within the central nervous system. The emergence of resistance to radiotherapy and chemotherapy represents a significant impediment to advancements in glioma treatment.

METHODS

We established temozolomide (TMZ)-resistant GBM cell lines by chronically exposing U87MG cell lines to TMZ, and dimethyl sulfoxide (DMSO) was used as placebo control. In vivo and in vitro experiments verified the resistance of resistant cells to chemotherapy and radiotherapy. LAT4 was identified by transcriptomics to be associated with GBM treatment resistance and relapse. The relationship between LAT4 and mTOR pathway activity was also analyzed. Finally, the effect of BCH (LAT inhibitor) combined with radiotherapy on GBM prognosis was verified in vivo.

RESULTS

We have first confirmed that TMZ not only induces resistance to chemotherapy in GBM cells but also enhances their resistance to radiotherapy, which is a significant finding in the process of building TMZ-resistant U87MG GBM cell lines. We then performed comprehensive transcriptomic analysis and identified amino acid metabolism as a potential key factor in radiotherapy resistance. Specifically, we confirmed that the upregulation of LAT4 following chemotherapy enhances leucine metabolism within tumors in vitro and in vivo, thereby modulating the mechanistic target of mTOR pathway and leading to radiotherapy resistance. Of note, the application of inhibitors targeting leucine metabolism was shown to restore the sensitivity of these cells to radiotherapy, highlighting a potential therapeutic strategy for overcoming resistance in GBM.

CONCLUSIONS

Our study links tumor sensitivity to chemotherapy and radiotherapy and highlights the critical role of LAT4 in activating the mTOR pathway and GBM radiotherapy resistance. It suggests ways to improve radiotherapy sensitivity to GBM.

Novel strategies to overcome chemoresistance in human glioblastoma

Temozolomide (TMZ) is currently the first-line chemotherapeutic agent for the treatment of glioblastoma multiforme (GBM). However, the inherent heterogeneity of GBM often results in suboptimal outcomes, particularly due to varying degrees of resistance to TMZ. Over the past several decades, O6-methylguanine-DNA methyltransferase (MGMT)-mediated DNA repair pathway has been extensively investigated as a target to overcome TMZ resistance. Nonetheless, the combination of small molecule covalent MGMT inhibitors with TMZ and other chemotherapeutic agents has frequently led to adverse clinical effects. Recently, additional mechanisms contributing to TMZ resistance have been identified, including epidermal growth factor receptor (EGFR) mutations, overactivation of intracellular signalling pathways, energy metabolism reprogramming or survival autophagy, and changes in tumor microenvironment (TME). These findings suggest that novel therapeutic strategies targeting these mechanisms hold promise for overcoming TMZ resistance in GBM patients. In this review, we summarize the latest advancements in understanding the mechanisms underlying intrinsic and acquired TMZ resistance. Additionally, we compile various small-molecule compounds with potential to mitigate chemoresistance in GBM. These mechanism-based compounds may enhance the sensitivity of GBM to TMZ and related chemotherapeutic agents, thereby improving overall survival rates in clinical practice.

Potential of Natural Products in the Treatment of Glioma: Focus on Molecular Mechanisms

Despite the waning of traditional treatments for glioma due to possible long-term issues, the healing possibilities of substances derived from nature have been reignited in the scientific community. These natural substances, commonly found in fruits and vegetables, are considered potential alternatives to pharmaceuticals, as they have been shown in prior research to impact pathways surrounding cancer progression, metastases, invasion, and resistance. This review will explore the supposed molecular mechanisms of different natural components, such as berberine, curcumin, coffee, resveratrol, epigallocatechin-3-gallate, quercetin, tanshinone, silymarin, coumarin, and lycopene, concerning glioma treatment. While the benefits of a balanced diet containing these compounds are widely recognized, there is considerable scope for investigating the efficacy of these natural products in treating glioma.

WNT and TGF-Beta Pathway Alterations in Early-Onset Colorectal Cancer Among Hispanic/Latino Populations

BACKGROUND/OBJECTIVES

One of the fastest-growing minority groups in the U.S. is the Hispanic/Latino population. Recent studies have shown how this population is being disproportionately affected by early-onset colorectal cancer (CRC). Compared to corresponding non-Hispanic White (NHW) patients, Hispanic/Latino patients have both higher incidence of disease and rates of mortality. Two well-established drivers of early-onset CRC in the general population are alterations in the WNT and TGF-Beta signaling pathways; however, the specific roles of these pathways in Hispanics/Latinos are poorly understood.

METHODS

Here, we assessed CRC mutations in the WNT and TGF-Beta pathways by conducting a bioinformatics analysis using cBioPortal. Cases of CRC were stratified both by age and ethnicity: (1) early-onset was defined as <50 years vs. late-onset as ≥50 years; (2) we compared early-onset in Hispanics/Latinos to early-onset in NHWs.

RESULTS

No significant differences were evident when we compared early-onset and late-onset CRC cases within the Hispanic/Latino cohort. These results are consistent with findings from large cohorts that do not specify ethnicity. However, we found significant differences when we compared early-onset CRC in Hispanic/Latino patients to early-onset CRC in NHW patients: specifically, alterations in the gene bone morphogenetic protein-7 (BMP7) were more frequent in early-onset CRC for the Hispanic/Latino patients. In addition to these findings, we observed that both NHW patients and Hispanic/Latino patients with early-onset disease had better clinical outcomes when there was evidence of WNT pathway alterations. Conversely, the absence of TGF-Beta pathway alterations was uniquely associated with improved outcomes exclusively in early-onset Hispanic/Latino patients.

CONCLUSIONS

In toto, these findings underscore how the WNT and TGF-Beta pathways may act differently in different ethnic groups with early-onset CRC. These findings may set a stage for developing new therapies tailored for reducing cancer health disparities.

MGST1 facilitates novel KRASG12D inhibitor resistance in KRASG12D-mutated pancreatic ductal adenocarcinoma by inhibiting ferroptosis

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer with a low 5-year survival rate. Treatment options for PDAC patients are limited. Recent studies have shown promising results with MRTX1133, a KRASG12D inhibitor that demonstrated potent antitumor activity in various types of tumors with KRASG12D mutation. Resistance to KRAS inhibitors is frequently occurred and one of the main reasons for treatment failure. Understanding resistance mechanisms to novel KRAS inhibitors is crucial to ensure sustained and durable remissions.

METHODS

Two KRASG12D inhibitor MRTX1133-resistant PDAC cell lines were established in vitro. The resistance mechanisms to KRASG12D inhibitor MRTX1133 against PDAC in vitro and in vivo were characterized by RNA sequencing, reverse transcript polymerase chain reaction, cytotoxicity test, plasmid transfection, lentivirus transfection, lipid peroxidation detection, malondialdehyde levels detection, glutathione levels detection, western blot, immunofluorescence, nude mice tumorigenesis experiment and immunohistochemistry.

RESULTS

The bioinformatics analysis and transcriptome sequencing showed that ferroptosis was involved in the resistant effect of the KRASG12D inhibitor treatment, and MGST1 was the key molecule against MRTX1133-induced ferroptosis. Increased expression of MGST1 weakened the cytotoxicity of MRTX1133 by inhibiting lipid peroxidation-induced ferroptosis in KRASG12D inhibitor-resistant PDAC cells. Knockdown or overexpression of MGST1 conferred sensitivity or resistance to KRASG12D inhibitor MRTX1133, respectively. Mechanismly, increased nuclear localization and higher levels of active β-catenin were observed in MRTX1133-resistant PDAC cells, which contributed to higher MGST1 expression. Knockdown of CTNNB1 or TCF4 can decreased MGST1 expression. Additionally, we found that PKF-118-310, an antagonist of β-catenin/Tcf4 complex, repressed MGST1 expression. In both in vitro and in vivo models, a synergistic effect was observed when combining MRTX1133 and PKF-118-310 in KRASG12D inhibitor MRTX1133-resistant PDAC cells and tumors.

CONCLUSION

Our data showed that KRASG12D inhibitor MRTX1133 combined with PKF-118-310 could enhance the effectiveness of MRTX1133 treatment response through induction of ferroptosis via inhibiting MGST1 expression in MRTX1133-resistant PDAC cells and tumors. This evidence may provide a promising strategy to overcome KRASG12D inhibitor MRTX1133 resistance in PDAC patients with KRASG12D mutations.

Unraveling the mysteries of MGMT: Implications for neuroendocrine tumors

Neuroendocrine tumors (NETs) are a diverse group of tumors that arise from neuroendocrine cells and are commonly found in various organs. A considerable proportion of NET patients were diagnosed at an advanced or metastatic stage. Alkylating agents are the primary treatment for NET, and O6-methylguanine methyltransferase (MGMT) remains the first-line of defense against DNA damage caused by these agents. Clinical trials have indicated that MGMT promoter methylation or its low/lacked expression can predict a favorable outcome with Temozolomide in NETs. Its status could help select NET patients who can benefit from alkylating agents. Therefore, MGMT status serves as a biomarker to guide decisions on the efficacy of Temozolomide as a personalized treatment option. Additionally, delving into the regulatory mechanisms of MGMT status can lead to the development of MGMT-targeted therapies, benefiting individuals with high levels of MGMT expression. This review aims to explore the polymorphism of MGMT regulation and summarize its clinical implications in NETs, which would help establish the role of MGMT as a biomarker and its potential as a therapeutic target in NETs. Additionally, we explore the benefits of combining Temozolomide and immunotherapy in MGMT hypermethylated subgroups. Future studies can focus on optimizing Temozolomide administration to induce specific immunomodulatory changes.

High expression of LncRNA HOTAIR is a risk factor for temozolomide resistance in glioblastoma via activation of the miR-214/β-catenin/MGMT pathway

HOX transcript antisense RNA (HOTAIR) is upregulated in glioblastoma (GBM) and associated with temozolomide (TMZ) resistance. However, the mechanisms underlying HOTAIR-mediated TMZ resistance remains poorly understood. HOTAIR expression in glioma-related public datasets and drug response estimation were analyzed using bioinformatics. These findings were verified by overexpressing HOTAIR in TMZ-sensitive U251 cells and/or silencing HOTAIR in resistant U251 cells (U251R). The cytotoxic effects were evaluated using cell viability assay and flow cytometry analysis of cell cycle and apoptosis. In this study, we found that HOTAIR was upregulated in TMZ-resistant GBM cell lines and patients with high HOTAIR expression responded poorly to TMZ therapy. HOTAIR knockdown restored TMZ sensitivity in U251R cells, while HOTAIR overexpression conferred TMZ resistance in U251 cells. Wnt/β-catenin signaling was enriched in patients with high HOTAIR expression; consistently, HOTAIR positively regulated β-catenin expression in U251 cells. Moreover, HOTAIR-mediated TMZ resistance was associated with increased MGMT protein level, which resulted from the HOTAIR/miR-214-3p/β-catenin network. Besides, GBM with high HOTAIR expression exhibited sensitivity to methotrexate. Methotrexate enhanced TMZ sensitivity in U251R cells, accompanied by reduced expression of HOTAIR and β-catenin. Thus, we conlcude that HOTAIR is a risk factor for TMZ resistance and methotrexate may represent a potential therapeutic drug for patients with high HOTAIR expression level.

A Methyl-Engineered DNAzyme for Endogenous Alkyltransferase Monitoring and Self-Sufficient Gene Regulation

The on-demand gene regulation is crucial for extensively exploring specific gene functions and developing personalized gene therapeutics, which shows great promise in precision medicines. Although some nucleic acid-based gene regulatory tools (antisense oligonucleotides and small interfering RNAs) are devised for achieving on-demand activation, the introduction of chemical modifications may cause undesired side effects, thereby impairing the gene regulatory efficacy. Herein, a methyl-engineered DNAzyme (MeDz) is developed for the visualization of endogenous alkyltransferase (AGT) and the simultaneous self-sufficiently on-demand gene regulation. The catalytic activity of DNAzyme can be efficiently blocked by O6-methylguanine (O6MeG) modification and specifically restored via the AGT-mediated DNA-repairing pathway. This simply designed MeDz is demonstrated to reveal AGT of varying expression levels in different cells, opening the possibility to explore the AGT-related biological processes. Moreover, the AGT-guided MeDz exhibits cell-selective regulation on the human early growth response-1 (EGR-1) gene, with efficient gene repression in breast cancer cells and low effectiveness in normal cells. The proposed MeDz offers an attractive strategy for on-demand gene regulation, displaying great potential in biomedical applications.

MEN1 Deficiency-Driven Activation of the β-Catenin-MGMT Axis Promotes Pancreatic Neuroendocrine Tumor Growth and Confers Temozolomide Resistance

O6-methylguanine DNA methyltransferase (MGMT) removes alkyl adducts from the guanine O6 position (O6-MG) and repairs DNA damage. High MGMT expression results in poor response to temozolomide (TMZ). However, the biological importance of MGMT and the mechanism underlying its high expression in pancreatic neuroendocrine tumors (PanNETs) remain elusive. Here, it is found that MGMT expression is highly elevated in PanNET tissues compared with paired normal tissues and negatively associated with progression-free survival (PFS) time in patients with PanNETs. Knocking out MGMT inhibits cancer cell growth in vitro and in vivo. Ectopic MEN1 expression suppresses MGMT transcription in a manner that depends on β-Catenin nuclear export and degradation. The Leucine 267 residue of MEN1 is crucial for regulating β-Catenin-MGMT axis activation and chemosensitivity to TMZ. Interference with β-Catenin re-sensitizes tumor cells to TMZ and significantly reduces the cytotoxic effects of high-dose TMZ treatment, and MGMT overexpression counteracts the effects of β-Catenin deficiency. This study reveals the biological importance of MGMT and a new mechanism by which MEN1 deficiency regulates its expression, thus providing a potential combinational strategy for treating patients with TMZ-resistant PanNETs.

Emissive Alkylated Guanine Analogs as Probes for Monitoring O 6-Alkylguanine-DNA-transferase Activity

Human O 6-alkylguanine-DNA-transferase (hAGT) is a repair protein that provides protection from mutagenic events caused by O 6-alkylguanine lesions. As this stoichiometric activity is tissue-specific, indicative of tumor status, and correlated to chemotherapeutic success, tracking the activity of hAGT could prove to be informative for disease diagnosis and therapy. Herein, we explore two families of emissive O 6-methyl- and O 6-benzylguanine analogs based on our previously described th G N and tz G N , thieno- and isothiazolo-guanine surrogates, respectively, as potential reporters. We establish that O 6 -Bn th G N and O 6 -Bn tz G N provide a spectral window to optically monitor hAGT activity, can be used as substrates for the widely used SNAP-Tag delivery system, and are sufficiently bright to be visualized in mammalian cells using fluorescence microscopy.

Artesunate Exerts Organ- and Tissue-Protective Effects by Regulating Oxidative Stress, Inflammation, Autophagy, Apoptosis, and Fibrosis: A Review of Evidence and Mechanisms

The human body comprises numerous organs and tissues operating in synchrony, it facilitates metabolism, circulation, and overall organismal function. Consequently, the well-being of our organs and tissues significantly influences our overall health. In recent years, research on the protective effects of artesunate (AS) on various organ functions, including the heart, liver, brain, lungs, kidneys, gastrointestinal tract, bones, and others has witnessed significant advancements. Findings from in vivo and in vitro studies suggest that AS may emerge as a newfound guardian against organ damage. Its protective mechanisms primarily entail the inhibition of inflammatory factors and affect anti-fibrotic, anti-aging, immune-enhancing, modulation of stem cells, apoptosis, metabolic homeostasis, and autophagy properties. Moreover, AS is attracting a high level of interest because of its obvious antioxidant activities, including the activation of Nrf2 and HO-1 signaling pathways, inhibiting the release of reactive oxygen species, and interfering with the expression of genes and proteins associated with oxidative stress. This review comprehensively outlines the recent strides made by AS in alleviating organismal injuries stemming from various causes and protecting organs, aiming to serve as a reference for further in-depth research and utilization of AS.

MGMT activated by Wnt pathway promotes cisplatin tolerance through inducing slow-cycling cells and nonhomologous end joining in colorectal cancer

Chemotherapy resistance plays a pivotal role in the prognosis and therapeutic failure of patients with colorectal cancer (CRC). Cisplatin (DDP)-resistant cells exhibit an inherent ability to evade the toxic chemotherapeutic drug effects which are characterized by the activation of slow-cycle programs and DNA repair. Among the elements that lead to DDP resistance, O 6-methylguanine (O 6-MG)-DNA-methyltransferase (MGMT), a DNA-repair enzyme, performs a quintessential role. In this study, we clarify the significant involvement of MGMT in conferring DDP resistance in CRC, elucidating the underlying mechanism of the regulatory actions of MGMT. A notable upregulation of MGMT in DDP-resistant cancer cells was found in our study, and MGMT repression amplifies the sensitivity of these cells to DDP treatment in vitro and in vivo. Conversely, in cancer cells, MGMT overexpression abolishes their sensitivity to DDP treatment. Mechanistically, the interaction between MGMT and cyclin dependent kinase 1 (CDK1) inducing slow-cycling cells is attainted via the promotion of ubiquitination degradation of CDK1. Meanwhile, to achieve nonhomologous end joining, MGMT interacts with XRCC6 to resist chemotherapy drugs. Our transcriptome data from samples of 88 patients with CRC suggest that MGMT expression is co-related with the Wnt signaling pathway activation, and several Wnt inhibitors can repress drug-resistant cells. In summary, our results point out that MGMT is a potential therapeutic target and predictive marker of chemoresistance in CRC.

VDRA downregulate β-catenin/Smad3 and DNA damage and repair associated with improved prognosis in ccRCC patients

The clear cell renal cell carcinoma (ccRCC) spotlighted the poorest survival, while chromophobe renal cell carcinoma (chRCC) was associated with the best survival. Earlier studies corroborated vitamin D receptor (VDR) was a promising molecular for improving the prognosis of RCC. In contrast to VDRA, the one of VDR isoforms, VDRB1 (VDR isoform B1) has an N-terminal extension of 50 amino acids and is less ligand-dependent. However, the functional differences between VDRA and VDRB1, and their roles in the prognosis of ccRCC and chRCC, have not been investigated. In the present study, we uncovered that the transcripts related to vitamin D pathway and cellular calcium signaling were effectively decreased in the context of ccRCC, yet failed to exert a comparable effect within chRCC. Specially, minimally levels of VDRA wherein kidneys of patients suffering from ccRCC predict shorter survival time. In addition, the protein expressions for β-catenin/Smad3 pathway and DNA damage and repair pathways were obviously impeded in VDRA-overexpressed ccRCC cells, yet this inhibitory effect was conspicuously absent in enable VDRB1 cells. Our results provide a new idea to improve the prognosis of ccRCC via VDRA upregulation.

Therapeutic Potential of Natural Compounds from Herbs and Nutraceuticals in Alleviating Neurological Disorders: Targeting the Wnt Signaling Pathway

As an important signaling pathway in multicellular eukaryotes, the Wnt signaling pathway participates in a variety of physiological processes. Recent studies have confirmed that the Wnt signaling pathway plays an important role in neurological disorders such as stroke, Alzheimer's disease, and Parkinson's disease. The regulation of Wnt signaling by natural compounds in herbal medicines and nutraceuticals has emerged as a potential strategy for the development of new drugs for neurological disorders. Purpose: The aim of this review is to evaluate the latest research results on the efficacy of natural compounds derived from herbs and nutraceuticals in the prevention and treatment of neurological disorders by regulating the Wnt pathway in vivo and in vitro. A manual and electronic search was performed for English articles available from PubMed, Web of Science, and ScienceDirect from the January 2010 to February 2023. Keywords used for the search engines were "natural products,″ "plant derived products,″ "Wnt+ clinical trials,″ and "Wnt+,″ and/or paired with "natural products″/″plant derived products", and "neurological disorders." A total of 22 articles were enrolled in this review, and a variety of natural compounds from herbal medicine and nutritional foods have been shown to exert therapeutic effects on neurological disorders through the Wnt pathway, including curcumin, resveratrol, and querctrin, etc. These natural products possess antioxidant, anti-inflammatory, and angiogenic properties, confer neurovascular unit and blood-brain barrier integrity protection, and affect neural stem cell differentiation, synaptic formation, and neurogenesis, to play a therapeutic role in neurological disorders. In various in vivo and in vitro studies and clinical trials, these natural compounds have been shown to be safe and tolerable with few adverse effects. Natural compounds may serve a therapeutic role in neurological disorders by regulating the Wnt pathway. This summary of the research progress of natural compounds targeting the Wnt pathway may provide new insights for the treatment of neurological disorders and potential targets for the development of new drugs.

Long non-coding RNA (lncRNA) PVT1 in drug resistance of cancers: Focus on pathological mechanisms

According to estimates, cancer will be the leading cause of death globally in 2022, accounting for 9.6 million deaths. At present, the three main therapeutic modalities utilized to treat cancer are radiation therapy, chemotherapy, and surgery. However, during treatment, tumor cells resistant to chemotherapy may arise. Drug resistance remains a major oppose since it often leads to therapeutic failure. Furthermore, the term "acquired drug resistance" describes the situation where tumor cells already display drug resistance before undergoing chemotherapy. However, little is still known about the basic mechanisms underlying chemotherapy-induced drug resistance. The development of new technologies and bioinformatics has led to the discovery of additional genes associated with drug resistance. Long noncoding RNA plasmacytoma variant translocation 1 (PVT1) has been linked to an increased risk of cancer, according to a growing body of research. Apart from biological functions associated with cell division, development, pluripotency, and cell cycle, lncRNA PVT1 contributes significantly to the regulation of various aspects of genome function, such as transcription, splicing, and epigenetics. The article will address the mechanism by which lncRNA PVT1 influences drug resistance in cancer cells.

Death-associated protein 3 in cancer-discrepant roles of DAP3 in tumours and molecular mechanisms

Cancer, ranks as the secondary cause of death, is a group of diseases that are characterized by uncontrolled tumor growth and distant metastasis, leading to increased mortality year-on-year. To date, targeted therapy to intercept the aberrant proliferation and invasion is crucial for clinical anticancer treatment, however, mutant expression of target genes often leads to drug resistance. Therefore, it is essential to identify more molecules that can be targeted to facilitate combined therapy. Previous studies showed that death associated protein 3 (DAP3) exerts a pivotal role in regulating apoptosis signaling of tumors, meanwhile, aberrant DAP3 expression is associated with the tumorigenesis and disease progression of various cancers. This review provides an overview of the molecule structure of DAP3 and the discrepant roles played by DAP3 in various types of tumors. Considering the molecular mechanism of DAP3-regulated cancer development, new potential treatment strategies might be developed in the future.

Inhibition of PORCN Blocks Wnt Signaling to Attenuate Progression of Oral Carcinogenesis

PURPOSE

Oral squamous cell carcinoma (OSCC) is commonly preceded by potentially malignant lesions, referred to as oral dysplasia. We recently reported that oral dysplasia is associated with aberrant activation of the Wnt/β-catenin pathway, due to overexpression of Wnt ligands in a Porcupine (PORCN)-dependent manner. Pharmacologic inhibition of PORCN precludes Wnt secretion and has been proposed as a potential therapeutic approach to treat established cancers. Nevertheless, there are no studies that explore the effects of PORCN inhibition at the different stages of oral carcinogenesis.

EXPERIMENTAL DESIGN

We performed a model of tobacco-induced oral cancer in vitro, where dysplastic oral keratinocytes (DOK) were transformed into oral carcinoma cells (DOK-TC), and assessed the effects of inhibiting PORCN with the C59 inhibitor. Similarly, an in vivo model of oral carcinogenesis and ex vivo samples derived from patients diagnosed with oral dysplasia and OSCC were treated with C59.

RESULTS

Both in vitro and ex vivo oral carcinogenesis approaches revealed decreased levels of nuclear β-catenin and Wnt3a, as observed by immunofluorescence and IHC analyses. Consistently, reduced protein and mRNA levels of survivin were observed after treatment with C59. Functionally, treatment with C59 in vitro resulted in diminished cell migration, viability, and invasion. Finally, by using an in vivo model of oral carcinogenesis, we found that treatment with C59 prevented the development of OSCC by reducing the size and number of oral tumor lesions.

CONCLUSIONS

The inhibition of Wnt ligand secretion with C59 represents a feasible treatment to prevent the progression of early oral lesions toward OSCC.

PYGO2 increases proliferation and migration capacities through critical signaling pathways in esophageal squamous cell carcinoma

Esophageal cancer, an increasingly prevalent malignancy, is a major concern for global health. The development of esophageal squamous cell carcinoma (ESCC) involves various genetic abnormalities that affect key cell signaling pathways, including Wnt, Hh, Apoptosis, MAPK, EGFR, AKT, Notch, and EMT. Additionally, this malignancy involves some changes in the expression of long noncoding RNAs (LncRNAs). The present study examines the relationship between PYGO2 gene expression and the activity of cell signaling pathways in KYSE-30 and YM-1ESCC cell lines. To this end, several cellular and molecular tests were performed, including cell migration, cell cycle, and apoptosis. Also, expression levels of CD133 and CD44 markers, real-time PCR, and western blot were analyzed after inducing PYGO2 protein expression in the cells. Overexpression of the PYGO2 protein resulted in the upregulation of Wnt pathway-related genes, leading to enhanced cell migration and proliferation and reduced apoptosis in both cell lines. Furthermore, PYGO2 gene expression induction analysis showed the correlation of several involved genes in Wnt, Hh, Apoptosis, MAPK, EGFR, AKT, and EMT pathways with various LncRNAs.

EGFR-targeting peptide conjugated polymer-lipid hybrid nanoparticles for delivery of salinomycin to osteosarcoma

CONTEXT

Salinomycin (SAL) is a chemotherapeutic drug with anti-osteosarcoma efficacy, but its hydrophobic properties have hindered its application. Nanoparticles have been widely used as drug carriers to improve the solubility of hydrophobic drugs. The dodecapeptide GE11 has been shown to have great binding affinity to the epidermal growth factor receptor (EGFR), which is highly overexpressed in osteosarcoma.

MATERIALS AND METHODS

We designed novel SAL-loaded GE11-conjugated polymer-lipid hybrid nanoparticles (GE11-NPs-SAL) to target osteosarcoma. The characterization and antitumor activity of GE11-NPs-SAL were evaluated both in vitro and in vivo.

RESULTS

The results showed that GE11-NPs-SAL had a size of ~100 nm with a high encapsulation efficacy of ~80%. Compared with the non-targeted nanoparticles, GE11-NPs-SAL showed increased internalization in osteosarcoma cells and improved therapeutic efficacy in osteosarcoma both in vitro and in vivo.

CONCLUSIONS

GE11-NPs-SAL is a promising treatment for osteosarcoma.

Crosstalk between Non-Coding RNAs and Wnt/β-Catenin Signaling in Head and Neck Cancer: Identification of Novel Biomarkers and Therapeutic Agents

Head and neck cancers (HNC) encompass a broad spectrum of neoplastic disorders characterized by significant morbidity and mortality. While contemporary therapeutic interventions offer promise, challenges persist due to tumor recurrence and metastasis. Central to HNC pathogenesis is the aberration in numerous signaling cascades. Prominently, the Wnt signaling pathway has been critically implicated in the etiology of HNC, as supported by a plethora of research. Equally important, variations in the expression of non-coding RNAs (ncRNAs) have been identified to modulate key cancer phenotypes such as cellular proliferation, epithelial-mesenchymal transition, metastatic potential, recurrence, and treatment resistance. This review aims to provide an exhaustive insight into the multifaceted influence of ncRNAs on HNC, with specific emphasis on their interactions with the Wnt/β-catenin (WBC) signaling axis. We further delineate the effect of ncRNAs in either exacerbating or attenuating HNC progression via interference with WBC signaling. An overview of the mechanisms underlying the interplay between ncRNAs and WBC signaling is also presented. In addition, we described the potential of various ncRNAs in enhancing the efficacy of chemotherapeutic and radiotherapeutic modalities. In summary, this assessment posits the potential of ncRNAs as therapeutic agents targeting the WBC signaling pathway in HNC management.

Neolignan derivatives from Penthorum chinense with antitumor activity in human colorectal cancer cells by regulating Wnt/β-catenin signaling pathway

In vitro cytotoxicity-guided isolation based on a MTT assay was conducted for Penthorum chinense Pursh. (Penthoraceae). In the active components (EtOAc extract of P. chinense), eight undescribed neolignans, penthoneolignans A-H (1-8), and two known analogs (9 and 10) were obtained and identified. Their absolute configurations were determined by experimental and computational comparison of electronic circular dichroism spectra analysis. The MTT experiment results of the obtained neolignans on HT29 and LoVo cells indicated previously undescribed neolignans, penthoneolignans A (1) and F (6), showed better cytotoxicity than the positive drug 5-fluorouracil. Then, functional technologies such as the 5-ethyny1-2'-deoxyridine, wound healing, Transwell, and Western blot assays indicated that they could significantly inhibit the proliferation of HT29 and Lovo cells, promote apoptosis by up-regulating Bax, and down-regulating B-cell CLL/lymphoma 2 and poly ADP-ribose polymerase. Furthermore, a Western blot assay combining the Dsh homolog 2 agonist IWP-L6 and the β-catenin agonist MG132 suggested their mechanism of action was closely related to the inhibition of the Wnt/β-catenin signaling pathway. In conclusion, previously undescribed neolignans, penthoneolignans A (1) and F (6), may intervene in the development and progression of colorectal cancer by inhibiting the Wnt/β-catenin signaling pathway and have the potential to be drug candidates.

Modulating MGMT expression through interfering with cell signaling pathways

Guanine O6-alkylating agents are widely used as first-line chemotherapeutic drugs due to their ability to induce cytotoxic DNA damage. However, a major hurdle in their effectiveness is the emergence of chemoresistance, largely attributed to the DNA repair pathway mediated by O6-methylguanine-DNA methyltransferase (MGMT). MGMT plays an important role in removing the alkyl groups from lethal O6-alkylguanine (O6-AlkylG) adducts formed by chemotherapeutic alkylating agents. By doing so, MGMT enables tumor cells to evade apoptosis and develop drug resistance toward DNA alkylating agents. Although covalent inhibitors of MGMT, such as O6-benzylguanine (O6-BG) and O6-(4-bromothenyl)guanine (O6-4-BTG or lomeguatrib), have been explored in clinical settings, their utility is limited due to severe delayed hematological toxicity observed in most patients when combined with alkylating agents. Therefore, there is an urgent need to identify new targets and unravel the underlying molecular mechanisms and to develop alternative therapeutic strategies that can overcome MGMT-mediated tumor resistance. In this context, the regulation of MGMT expression via interfering the specific cell signaling pathways (e.g., Wnt/β-catenin, NF-κB, Hedgehog, PI3K/AKT/mTOR, JAK/STAT) emerges as a promising strategy for overcoming tumor resistance, and ultimately enhancing the efficacy of DNA alkylating agents in chemotherapy.

METTL3-mediated m6A modification of LINC00839 maintains glioma stem cells and radiation resistance by activating Wnt/β-catenin signaling

Long noncoding RNAs (lncRNAs) are involved in glioma initiation and progression. Glioma stem cells (GSCs) are essential for tumor initiation, maintenance, and therapeutic resistance. However, the biological functions and underlying mechanisms of lncRNAs in GSCs remain poorly understood. Here, we identified that LINC00839 was overexpressed in GSCs. A high level of LINC00839 was associated with GBM progression and radiation resistance. METTL3-mediated m6A modification on LINC00839 enhanced its expression in a YTHDF2-dependent manner. Mechanistically, LINC00839 functioned as a scaffold promoting c-Src-mediated phosphorylation of β-catenin, thereby inducing Wnt/β-catenin activation. Combinational use of celecoxib, an inhibitor of Wnt/β-catenin signaling, greatly sensitized GSCs to radiation. Taken together, our results showed that LINC00839, modified by METTL3-mediated m6A, exerts tumor progression and radiation resistance by activating Wnt/β-catenin signaling.

The Glioblastoma Landscape: Hallmarks of Disease, Therapeutic Resistance, and Treatment Opportunities

Malignant brain tumors are aggressive and difficult to treat. Glioblastoma is the most common and lethal form of primary brain tumor, often found in patients with no genetic predisposition. The median life expectancy for individuals diagnosed with this condition is 6 months to 2 years and there is no known cure. New paradigms in cancer biology implicate a small subset of tumor cells in initiating and sustaining these incurable brain tumors. Here, we discuss the heterogenous nature of glioblastoma and theories behind its capacity for therapy resistance and recurrence. Within the cancer landscape, cancer stem cells are thought to be both tumor initiators and major contributors to tumor heterogeneity and therapy evasion and such cells have been identified in glioblastoma. At the cellular level, disruptions in the delicate balance between differentiation and self-renewal spur transformation and support tumor growth. While rapidly dividing cells are more sensitive to elimination by traditional treatments, glioblastoma stem cells evade these measures through slow division and reversible exit from the cell cycle. At the molecular level, glioblastoma tumor cells exploit several signaling pathways to evade conventional therapies through improved DNA repair mechanisms and a flexible state of senescence. We examine these common evasion techniques while discussing potential molecular approaches to better target these deadly tumors. Equally important, the presented information encourages the idea of augmenting conventional treatments with novel glioblastoma stem cell-directed therapies, as eliminating these harmful progenitors holds great potential to modulate tumor recurrence.

Quercetin induces MGMT+ glioblastoma cells apoptosis via dual inhibition of Wnt3a/β-Catenin and Akt/NF-κB signaling pathways

BACKGROUND

Surgical resection combined with radiotherapy and chemotherapy remains a common clinical treatment for glioblastoma multiforme (GBM). However, the therapeutic outcomes have not been satisfying due to drug resistance and other factors. Quercetin, a phytoingredient capable of crossing the blood-brain barrier, has shown effectiveness in the treatment of various solid tumors. Nevertheless, the potential of quercetin in GBM treatment has not been adequately explored.

PURPOSE

This study aims to investigate the effects and mechanisms of quercetin on MGMT⁺GBM cells.

METHODS

The potential targets and mechanisms of quercetin in glioma treatment were predicted based on network pharmacology and molecular docking. The effects of quercetin on cell inhibition rate, cell migration ability, cell cycle arrest, mitochondrial membrane potential (MMP), reactive oxygen species (ROS), Mitochondrial superoxide formation and apoptosis were measured by the CCK8 assay, wound healing assay, PI/RNase staining, JC-1 assay, DCFH-DA assay, MitoSOX staining and Annexin V-FITC/PI double staining, respectively. The methylation status of the MGMT promoter was assessed through methylation-specific polymerase chain reaction (MS-PCR). DNA damage was quantified by alkaline/neutral comet assay and TUNEL assay. The intracellular localization and expression of NF-κB and MGMT were revealed by immunofluorescence. The expression of migration-related proteins, matrix metalloproteinases, apoptosis-related proteins, cyclins, DNA damage/repair enzymes and related pathway proteins was detected by Western blot.

RESULTS

Network pharmacology identified 96 targets and potential molecular mechanisms of quercetin in glioma treatment. Subsequent experiments confirmed the synergistic effect of quercetin in combination with temozolomide (TMZ) on T98G cells. Quercetin significantly suppressed the growth and migration of human GBM T98G cells, induced apoptosis, and arrested cells in the S-phase cell cycle. The collapse of mitochondrial membrane potential, ROS generation, enhanced Bax/Bcl-2 ratio, and strengthened cleaved-Caspase 9 and cleaved-Caspase 3 suggested the involvement of ROS-mediated mitochondria-dependent apoptosis in the process of quercetin-induced apoptosis. In addition, quercetin-induced apoptosis was accompanied by intense DNA double-strand breaks (DSBs), γH2AX foci formation, methylation of MGMT promoter, increased cleaved-PARP, and reduced MGMT expression. Quercetin may influence the expression of the key DNA repair enzyme, MGMT, by dual suppression of the Wnt3a/β-Catenin and the Akt/NF-κB signaling pathways, thereby promoting apoptosis. Inhibition of Wnt3a and Akt using specific inhibitors hindered MGMT expression.

CONCLUSION

Our study provides the first evidence that quercetin may induce apoptosis in MGMT⁺GBM cells via dual inhibition of the Wnt3a/β-Catenin pathway and the Akt/NF-κB signaling pathway. These findings suggest that quercetin could be a novel agent for improving GBM treatment, especially in TMZ-resistant GBM with high MGMT expression.

Wnt Signaling in Brain Tumors: A Challenging Therapeutic Target

The involvement of Wnt signaling in normal tissue homeostasis and disease has been widely demonstrated over the last 20 years. In particular, dysregulation of Wnt pathway components has been suggested as a relevant hallmark of several neoplastic malignancies, playing a role in cancer onset, progression, and response to treatments. In this review, we summarize the current knowledge on the instructions provided by Wnt signaling during organogenesis and, particularly, brain development. Moreover, we recapitulate the most relevant mechanisms through which aberrant Wnt pathway activation may impact on brain tumorigenesis and brain tumor aggressiveness, with a particular focus on the mutual interdependency existing between Wnt signaling components and the brain tumor microenvironment. Finally, the latest anti-cancer therapeutic approaches employing the specific targeting of Wnt signaling are extensively reviewed and discussed. In conclusion, here we provide evidence that Wnt signaling, due to its pleiotropic involvement in several brain tumor features, may represent a relevant target in this context, although additional efforts will be needed to: (i) demonstrate the real clinical impact of Wnt inhibition in these tumors; (ii) overcome some still unsolved concerns about the potential systemic effects of such approaches; (iii) achieve efficient brain penetration.

UBE2T Promotes Temozolomide Resistance of Glioblastoma Through Regulating the Wnt/β-Catenin Signaling Pathway

Purpose

Patients with glioblastoma (GBM) have poor prognosis and limited therapeutic options, largely because of chemoresistance to temozolomide (TMZ) treatment. Ubiquitin conjugating enzyme E2 T (UBE2T) plays a key role in regulating the malignancy of various tumors, including GBM; however, its role in TMZ resistance of GBM has not been elucidated. The purpose of this study was to clarify the role of UBE2T in mediating TMZ resistance and investigate the specific underlying mechanism.

Methods

Western blotting was used to detect the protein levels of UBE2T and Wnt/β-catenin-related factors. CCK-8, flow cytometry, and colony formation assays were used to examine the effect of UBE2T on TMZ resistance. Wnt/β-catenin signaling pathway activation was inhibited using XAV-939, and a xenograft mouse model was generated to clarify the function of TMZ in vivo.

Results

UBE2T knockdown sensitized GBM cells to TMZ treatment, whereas UBE2T overexpression promoted TMZ resistance. The specific UBE2T inhibitor, M435-1279, increased the sensitivity of GBM cells to TMZ. Mechanistically, our results demonstrated that UBE2T induces β-catenin nuclear translocation and increases the protein levels of downstream molecules, including survivin and c-Myc. Inhibition of Wnt/β-catenin signaling using XAV-939 blocked TMZ resistance due to UBE2T overexpression in GBM cells. In addition, UBE2T was shown to facilitate TMZ resistance by inducing Wnt/β-catenin signaling pathway activation in a mouse xenograft model. Combined treatment with TMZ and UBE2T inhibitor achieved superior tumor growth suppression relative to TMZ treatment alone.

Conclusion

Our data reveal a novel role of UBE2T in mediating TMZ resistance of GBM cells via regulating Wnt/β-catenin signaling. These findings indicate that targeting UBE2T has promising potential to overcome TMZ resistance of GBM.

Serine-arginine protein kinase 1 (SRPK1) promotes EGFR-TKI resistance by enhancing GSK3β Ser9 autophosphorylation independent of its kinase activity in non-small-cell lung cancer

Resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) is a major challenge for clinicians and patients with non-small cell lung cancer (NSCLC). Serine-arginine protein kinase 1 (SRPK1) is a key oncoprotein in the EGFR/AKT pathway that participates in tumorigenesis. We found that high SRPK1 expression was significantly associated with poor progression-free survival (PFS) in patients with advanced NSCLC undergoing gefitinib treatment. Both in vitro and in vivo assays suggested that SRPK1 reduced the ability of gefitinib to induce apoptosis in sensitive NSCLC cells independently of its kinase activity. Moreover, SRPK1 facilitated binding between LEF1, β-catenin and the EGFR promoter region to increase EGFR expression and promote the accumulation and phosphorylation of membrane EGFR. Furthermore, we verified that the SRPK1 spacer domain bound to GSK3β and enhanced its autophosphorylation at Ser9 to activate the Wnt pathway, thereby promoting the expression of Wnt target genes such as Bcl-X. The correlation between SRPK1 and EGFR expression was confirmed in patients. In brief, our research suggested that the SRPK1/GSK3β axis promotes gefitinib resistance by activating the Wnt pathway and may serve as a potential therapeutic target for overcoming gefitinib resistance in NSCLC.

Canonical Wnt Pathway Is Involved in Chemoresistance and Cell Cycle Arrest Induction in Colon Cancer Cell Line Spheroids

The presence of cancer stem cells (CSCs) has been associated with the induction of drug resistance and disease recurrence after therapy. 5-Fluorouracil (5FU) is widely used as the first-line treatment of colorectal cancer (CRC). However, its effectiveness may be limited by the induction of drug resistance in tumor cells. The Wnt pathway plays a key role in the development and CRC progression, but it is not clearly established how it is involved in CSCs resistance to treatment. This work aimed to investigate the role played by the canonical Wnt/β-catenin pathway in CSCs resistance to 5FU treatment. Using tumor spheroids as a model of CSCs enrichment of CRC cell lines with different Wnt/β-catenin contexts, we found that 5FU induces in all CRC spheroids tested cell death, DNA damage, and quiescence, but in different proportions for each one: RKO spheroids were very sensitive to 5FU, while SW480 were less susceptible, and the SW620 spheroids, the metastatic derivative of SW480 cells, displayed the highest resistance to death, high clonogenic capacity, and the highest ability for regrowth after 5FU treatment. Activating the canonical Wnt pathway with Wnt3a in RKO spheroids decreased the 5FU-induced cell death. But the Wnt/β-catenin pathway inhibition with Adavivint alone or in combination with 5FU in spheroids with aberrant activation of this pathway produced a severe cytostatic effect compromising their clonogenic capacity and diminishing the stem cell markers expression. Remarkably, this combined treatment also induced the survival of a small cell subpopulation that could exit the arrest, recover SOX2 levels, and re-grow after treatment.

The dual role of DNA repair protein MGMT in cancer prevention and treatment

Alkylating agents are genotoxic chemicals that can induce and treat various types of cancer. This occurs through covalent bonding with cellular macromolecules, in particular DNA, leading to the loss of functional integrity under the persistence of modifications upon replication. O6-alkylguanine (O6-AlkylG) adducts are proposed to be the most potent DNA lesions induced by alkylating agents. If not repaired correctly, these adducts can result, at the molecular level, in DNA point mutations, chromosome aberrations, recombination, crosslinking, and single- and double-strand breaks (SSB/DSBs). At the cellular level, these lesions can result in malignant transformation, senescence, or cell death. O6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein capable of removing the alkyl groups from O6-AlkylG adducts in a damage reversal process that can prevent the adverse biological effects of DNA damage caused by guanine O6-alkylation. MGMT can thereby defend normal cells against tumor initiation, however it can also protect tumor cells against the beneficial effects of chemotherapy. Hence, MGMT can play an important role in both the prevention and treatment of cancer; thus, it can be considered as a double-edged sword. From a clinical perspective, MGMT is a therapeutic target, and it is important to explore the rational development of its clinical exploitation.

Neural crest cells development and neuroblastoma progression: Role of Wnt signaling

Neuroblastoma (NB) is one of the most common heterogeneous extracranial cancers in infancy that arises from neural crest (NC) cells of the sympathetic nervous system. The Wnt signaling pathway, both canonical and noncanonical pathway, is a highly conserved signaling pathway that regulates the development and differentiation of the NC cells during embryogenesis. Reports suggest that aberrant activation of Wnt ligands/receptors in Wnt signaling pathways promote progression and relapse of NB. Wnt signaling pathways regulate NC induction and migration in a similar manner; it regulates proliferation and metastasis of NB. Inhibiting the Wnt signaling pathway or its ligands/receptors induces apoptosis and abrogates proliferation and tumorigenicity in all major types of NB cells. Here, we comprehensively discuss the Wnt signaling pathway and its mechanisms in regulating the development of NC and NB pathogenesis. This review highlights the implications of aberrant Wnt signaling in the context of etiology, progression, and relapse of NB. We have also described emerging strategies for Wnt-based therapies against the progression of NB that will provide new insights into the development of Wnt-based therapeutic strategies for NB.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

Fluoride in the Central Nervous System and Its Potential Influence on the Development and Invasiveness of Brain Tumours-A Research Hypothesis

The purpose of this review is to attempt to outline the potential role of fluoride in the pathogenesis of brain tumours, including glioblastoma (GBM). In this paper, we show for the first time that fluoride can potentially affect the generally accepted signalling pathways implicated in the formation and clinical course of GBM. Fluorine compounds easily cross the blood-brain barrier. Enhanced oxidative stress, disruption of multiple cellular pathways, and microglial activation are just a few examples of recent reports on the role of fluoride in the central nervous system (CNS). We sought to present the key mechanisms underlying the development and invasiveness of GBM, as well as evidence on the current state of knowledge about the pleiotropic, direct, or indirect involvement of fluoride in the regulation of these mechanisms in various tissues, including neural and tumour tissue. The effects of fluoride on the human body are still a matter of controversy. However, given the growing incidence of brain tumours, especially in children, and numerous reports on the effects of fluoride on the CNS, it is worth taking a closer look at these mechanisms in the context of brain tumours, including gliomas.

Guggulsterone inhibits migration and invasion through proteasomal and lysosomal degradation in human glioblastoma cells

Glioblastoma multiforme (GBM) is a deadly brain malignancy, and current therapies offer limited survival benefit. The phytosterol guggulsterone (GS) has been shown to exhibit antitumor efficacy. This study aimed to investigate the effects of GS on migration and invasion and its underlying mechanisms in human GBM cell lines. After GS treatment, the survival rate of GBM cells was reduced, and the migration and invasion abilities of GBM cells were significantly decreased. There was also concomitant decreased expression of focal adhesion complex, matrix metalloproteinase-2 (MMP2), MMP9 and cathepsin B. Furthermore, GS induced ERK phosphorylation and autophagy, with increased p62 and LC3B-II expression. Notably, treatment of in GBM cells with the proteasome inhibitor MG132 or the lysosome inhibitor NH4Cl reversed the GS-mediated inhibition of migration and invasion. In an orthotopic xenograft mouse model, immunohistochemical staining of brain tumor tissues demonstrated that MMP2 and cathepsin B expression was reduced in GS-treated mice. GS treatment inhibited GBM cell migration and invasion via proteasomal and lysosomal degradation, suggesting its therapeutic potential in clinical use in the future.

Signaling pathways in brain tumors and therapeutic interventions

Brain tumors, although rare, contribute to distinct mortality and morbidity at all ages. Although there are few therapeutic options for brain tumors, enhanced biological understanding and unexampled innovations in targeted therapies and immunotherapies have considerably improved patients' prognoses. Nonetheless, the reduced response rates and unavoidable drug resistance of currently available treatment approaches have become a barrier to further improvement in brain tumor (glioma, meningioma, CNS germ cell tumors, and CNS lymphoma) treatment. Previous literature data revealed that several different signaling pathways are dysregulated in brain tumor. Importantly, a better understanding of targeting signaling pathways that influences malignant behavior of brain tumor cells might open the way for the development of novel targeted therapies. Thus, there is an urgent need for a more comprehensive understanding of the pathogenesis of these brain tumors, which might result in greater progress in therapeutic approaches. This paper began with a brief description of the epidemiology, incidence, risk factors, as well as survival of brain tumors. Next, the major signaling pathways underlying these brain tumors' pathogenesis and current progress in therapies, including clinical trials, targeted therapies, immunotherapies, and system therapies, have been systemically reviewed and discussed. Finally, future perspective and challenges of development of novel therapeutic strategies in brain tumor were emphasized.

miR-219-5p attenuates cisplatin resistance of ovarian cancer by inactivating Wnt/β-catenin signaling and autophagy via targeting HMGA2

Our previous study confirmed that miR-219-5p inhibits the progression of ovarian cancer (OC) by targeting high mobility group AT-hook 2 (HMGA2), while the role of miR-219-5p on the chemoresistance of OC is unclear. HMGA2 and miR-219-5p expression in OC tumors and various types of OC cells were determined by reverse transcription-quantitative PCR (RT-qPCR) and western blotting. The miRNA profiles in A2780 and cisplatin-resistant A2780 cells were investigated via bulk miRNA sequencing, and the interactions of miR-219-5p and HMGA2 were determined by luciferase reporter activity assay. Cell function was verified through Cell Counting Kit-8, invasion assay, wound-healing, and TUNEL assays. HMGA2 level is highly expressed in cisplatin-resistant OC cell lines compared to normal OC cells, while the expression trend of miR-219-5p is the opposite. In addition, we found that miR-219-5p is one of the miRNAs that have the most significant reduction in levels in the cisplatin-resistant A2780/DDP cell line compared to A2780 cells. Then, we reveal that miR-219-5p directly targets HMGA2 in cisplatin-resistant OC cells, and upregulation of miR-219-5p significantly reduces the resistance of OC cells to cisplatin both in vitro and in vivo. Finally, our results suggest that Wnt/β-catenin signaling and autophagy pathway is involved in the role of miR-219-5p/HMGA2 on resistance of OC cells to cisplatin via gain-of-function experiments. Collectively, the present study shows that miR-219-5p decreases the resistance of OC cells to cisplatin via Wnt/β-catenin signaling and autophagy by regulating HMGA2, which provides a feasible solution for the resistance of OC to chemotherapy.

A hypoxia-dissociable siRNA nanoplatform for synergistically enhanced chemo-radiotherapy of glioblastoma

Glioblastoma (GBM), as the most aggressive adult brain tumor, seriously threatened people's lives with a low survival time. Standard postoperative treatment, chemotherapy combined with radiotherapy (RT), was the major therapeutic strategy for GBM. However, this therapeutic efficacy was hindered by chemoradiotherapy resistance of GBM. Herein, to sensitize temozolomide (TMZ)-based chemotherapy and RT, a hypoxia-radiosensitive nanoparticle for co-delivering TMZ and siMGMT (RDPP(Met)/TMZ/siMGMT) was synthesized in this study. Our nanoparticle could effectively release the encapsulated alkylating agent (TMZ) and small interfering O6-methylguanine-DNA-methyltransferase RNA (siMGMT) in the hypoxic GBM. DNA-damage repair was effectively inhibited by down-regulating MGMT expression and activating cell apoptosis, which obviously enhanced the sensitivity of TMZ as well as RT. In vitro and in vivo experiments showed that RDPP(Met)/TMZ/siMGMT could efficiently penetrate the blood-brain barrier (BBB), accurately target GBM cells and effectively inhibit GBM proliferation. Compared with traditional TMZ combined with RT, RDPP(Met)/TMZ/siMGMT remarkably improved the survival time of orthotopic GBM-bearing mice, which demonstrated that our nanoplatform was an efficient combinatorial GBM therapy.

Cancer Metastasis and Treatment Resistance: Mechanistic Insights and Therapeutic Targeting of Cancer Stem Cells and the Tumor Microenvironment

Cancer metastasis and treatment resistance are the main causes of treatment failure and cancer-related deaths. Their underlying mechanisms remain to be fully elucidated and have been attributed to the presence of cancer stem cells (CSCs)-a small population of highly tumorigenic cancer cells with pluripotency and self-renewal properties, at the apex of a cellular hierarchy. CSCs drive metastasis and treatment resistance and are sustained by a dynamic tumor microenvironment (TME). Numerous pathways mediate communication between CSCs and/or the surrounding TME. These include a paracrine renin-angiotensin system and its convergent signaling pathways, the immune system, and other signaling pathways including the Notch, Wnt/β-catenin, and Sonic Hedgehog pathways. Appreciation of the mechanisms underlying metastasis and treatment resistance, and the pathways that regulate CSCs and the TME, is essential for developing a durable treatment for cancer. Pre-clinical and clinical studies exploring single-point modulation of the pathways regulating CSCs and the surrounding TME, have yielded partial and sometimes negative results. This may be explained by the presence of uninhibited alternative signaling pathways. An effective treatment of cancer may require a multi-target strategy with multi-step inhibition of signaling pathways that regulate CSCs and the TME, in lieu of the long-standing pursuit of a 'silver-bullet' single-target approach.

Emerging trends and research foci of epithelial-mesenchymal transition in gliomas: A scientometric analysis and review

BACKGROUND

Epithelial-mesenchymal transition (EMT) is a key factor in the invasion and migration of glioma cells, and the study of EMT in gliomas has become a hot topic over the past decade. Scientometric analysis is gaining more attention since it can obtain hot topics and emerging trends in a research field. This article analyzed the research related to EMT in gliomas for the first time, including descriptions of research situations, evaluations of research foci, and predictions of emerging trends.

METHODS

We searched the topic-related original articles from January 2012 to December 2021 in the Web of Science Core Collection (WoSCC) by using a specific strategy, and a total of 1,217 publications were obtained. The WoS platform, VOS viewer, and CiteSpace were used to analyze the annual distribution of publications and citations, authors and density of keywords, and other analyses including countries, institutions, references, clustering, burst analysis, and the timeline view of keywords.

RESULTS

Scientometric analysis identified that the study of EMT in gliomas has developed fast and received continuous attention in the last decade. Based on the results of data analysis, most publications on the topic came from China, and the United States had the highest betweenness centrality. The top 10 co-cited references revealed the landmark documents that had greatly promoted the development of this field. The major focus is on the cellular and molecular mechanisms of EMT in gliomas, and the therapy related to EMT target and non-coding RNAs has been developing fast in recent years.

CONCLUSIONS

This study revealed the intimate connections between EMT and gliomas, and the complex mechanisms regulating EMT in gliomas had been studied widely in the last decade. Exploring the deep mechanisms of EMT in gliomas is the foundation of the targeted inhibitions, which can promote the development of therapies for gliomas.

Potentiation of temozolomide activity against glioblastoma cells by aromatase inhibitor letrozole

PURPOSE

The DNA alkylating agent temozolomide (TMZ), is the first-line therapeutic for the treatment of glioblastoma (GBM). However, its use is confounded by the occurrence of drug resistance and debilitating adverse effects. Previously, we observed that letrozole (LTZ), an aromatase inhibitor, has potent activity against GBM in pre-clinical models. Here, we evaluated the effect of LTZ on TMZ activity against patient-derived GBM cells.

METHODS

Employing patient-derived G76 (TMZ-sensitive), BT142 (TMZ-intermediately sensitive) and G43 and G75 (TMZ-resistant) GBM lines we assessed the influence of LTZ and TMZ on cell viability and neurosphere growth. Combination Index (CI) analysis was performed to gain quantitative insights of this interaction. We then assessed DNA damaging effects by conducting flow-cytometric analysis of ˠH2A.X formation and induction of apoptotic signaling pathways (caspase3/7 activity). The effects of adding estradiol on LTZ-induced cytotoxicity and DNA damage were also evaluated.

RESULTS

Co-treatment with LTZ at a non-cytotoxic concentration (40 nM) reduced TMZ IC50 by 8, 37, 240 and 640 folds in G76, BT-142, G43 and G75 cells, respectively. The interaction was deemed to be synergistic based on CI analysis. LTZ co-treatment also significantly increased DNA damaging effects of TMZ. Addition of estradiol abrogated these LTZ effects.

CONCLUSIONS

LTZ increases DNA damage and synergistically enhances TMZ activity in TMZ sensitive and TMZ-resistant GBM lines. These effects are abrogated by the addition of exogenous estradiol underscoring that the observed effects of LTZ may be mediated by estrogen deprivation. Our study provides a strong rationale for investigating the clinical potential of combining LTZ and TMZ for GBM therapy.

Reducing Chemo-/Radioresistance to Boost the Therapeutic Efficacy against Temozolomide-Resistant Glioblastoma

Chemo-/radioresistance is the most important reason for the failure of glioblastoma (GBM) treatment. Reversing the chemo-/radioresistance of GBM for boosting therapeutic efficacy is very challenging. Herein, we report a significant decrease in the chemo-/radioresistance of GBM by the in situ generation of SO₂ within a tumor, which was released on demand from the prodrug 5-amino-1,3-dihydrobenzo[c]thiophene 2,2-dioxide (ATD) loaded on rare-earth-based scintillator nanoparticles (i.e., NaYF₄:Ce@NaLuF₄:Nd@ATD@DSPE-PEG₅₀₀₀, ScNPs) under X-ray irradiation. Our novel X-ray-responsive ScNPs efficiently converted highly penetrating X-rays into ultraviolet rays for controlling the decomposition of ATD to generate SO₂, which effectively damaged the mitochondria of temozolomide-resistant U87 cells to lower the production of ATP and inhibit P-glycoprotein (P-gp) expression to reduce drug efflux. Meanwhile, the O⁶-methylguanine-DNA methyltransferase (MGMT) of drug-resistant tumor cells was also reduced to prevent the repair of damaged DNA and enhance cell apoptosis and the efficacy of chemo-/radiotherapy. The tumor growth was obviously suppressed, and the mice survived significantly longer than untreated temozolomide-resistant GBM-bearing mice. Our work demonstrates the potential of SO₂ in reducing chemo-/radioresistance to improve the therapeutic effect against resistant tumors if it can be well controlled and in situ generated in tumor cells. It also provides insights into the rational design of stimuli-responsive drug delivery systems for the controlled release of drugs.

Targeted liposomes for combined delivery of artesunate and temozolomide to resistant glioblastoma

The effective treatment of glioblastoma (GBM) is a great challenge because of the blood-brain barrier (BBB) and the growing resistance to single-agent therapeutics. Targeted combined co-delivery of drugs could circumvent these challenges; however, the absence of more effective combination drug delivery strategies presents a potent barrier. Here, a unique combination ApoE-functionalized liposomal nanoplatform based on artesunate-phosphatidylcholine (ARTPC) encapsulated with temozolomide (ApoE-ARTPC@TMZ) was presented that can successfully co-deliver dual therapeutic agents to TMZ-resistant U251-TR GBM in vivo. Examination in vitro showed ART-mediated inhibition of DNA repair through the Wnt/β-catenin signaling cascade, which also improved GBM sensitivity to TMZ, resulting in enhanced synergistic DNA damage and induction of apoptosis. In assessing BBB permeation, the targeted liposomes were able to effectively traverse the BBB through low-density lipoprotein family receptors (LDLRs)-mediated transcytosis and achieved deep intracranial tumor penetration. More importantly, the targeted combination liposomes resulted in a significant decrease of U251-TR glioma burden in vivo that, in concert, substantially improved the survival of mice. Additionally, by lowering the effective dosage of TMZ, the combination liposomes reduced systemic TMZ-induced toxicity, highlighting the preclinical potential of this novel integrative strategy to deliver combination therapies to brain tumors.