Inhibition of autophagy and induction of glioblastoma cell death by NEO214, a perillyl alcohol-rolipram conjugate

The phosphodiesterase-4 inhibitor Zl-n-91 suppresses glioblastoma growth via EGR1/PTEN/AKT pathway

Glioblastoma multiforme (GBM) is a highly heterogeneous and aggressive brain tumor, which presents significant challenges for treatment in clinical settings. Phosphodiesterase 4 (PDE4) inhibitors can prevent the degradation of cAMP and have been used as a potential targeted therapeutic approach for different cancer types. However, their clinical use is restricted by side effects such as nausea and vomiting. Herein, we investigated the efficacy and therapeutic mechanisms of a specific PDE4 inhibitor, Zl-n-91, on GBM cells. The results demonstrated that Zl-n-91 exhibited greater effectiveness than the well-known PDE4 inhibitor Rolipram in treating GBM. It can notably suppress the proliferation of GBM cells by inducing G0/G1 phase arrest and apoptosis. Additionally, Zl-n-91 significantly inhibited the growth of subcutaneous glioma xenografts. Mechanistically, Zl-n-91 treatment increased the expression and nuclear transcription of Early growth response (EGR1), while knockdown of EGR1 could decrease PTEN levels and increase p-AKT levels, restoring the inhibition of cell proliferation induced by Zl-n-91. Collectively, we revealed for the first time that PDE4 inhibitor Zl-n-91 could inhibit the growth of GBM cells through the EGR1/PTEN/AKT signaling pathway. Zl-n-91, a specific PDE4 inhibitor, may be a promising therapeutic candidate for GBM.

Deapioplatycodin D inhibits glioblastoma cell proliferation by inducing BNIP3L-mediated incomplete mitophagy

Deapioplatycodin D (DPD) is a triterpenoid saponin natural compound isolated from the Chinese herb Platycodon grandiflorum that has antiviral and antitumor properties. This study aimed to investigate the effects of DPD on glioblastoma (GBM) cells and to determine its intrinsic mechanism of action. Using a CCK8 assay, it was found that DPD significantly inhibited the growth of GBM cells. DPD-treated GBM cells contained swollen and degenerated mitochondria with empty vesicular bilayer membrane-like autophagic vesicle structures in the periphery of the mitochondria under transmission electron microscopy. DPD activated autophagy in GBM cells and induced a blockage of autophagic flux in the late stage. Transcriptomics identified differences in mitophagy-related genes, and analysis of the levels of the corresponding proteins indicated that mitophagy in GBM cells was induced mainly through BNIP3L. Increased expression of BNIP3L disrupts the Bcl-2-Beclin-1 complex, thereby releasing Beclin-1 and activating autophagy. Autophagy was inhibited after silencing of BNIP3L and overexpression of Bcl-2 in GBM cells, and the growth inhibitory effect of DPD was significantly reduced. This result demonstrated that DPD induces mitophagy in GBM cells through BNIP3L. Finally, activation of incomplete mitophagy in GBM cells by DPD through BNIP3L in vivo was demonstrated by establishing a mouse subcutaneous xenograft tumor model. In this study, in vitro and in vivo experiments established that DPD inhibited GBM cell growth by inducing BNIP3L-mediated incomplete mitophagy, which provides an experimental basis for studying new treatments of GBM.

Autophagy in brain tumors: molecular mechanisms, challenges, and therapeutic opportunities

Autophagy is responsible for maintaining cellular balance and ensuring survival. Autophagy plays a crucial role in the development of diseases, particularly human cancers, with actions that can either promote survival or induce cell death. However, brain tumors contribute to high levels of both mortality and morbidity globally, with resistance to treatments being acquired due to genetic mutations and dysregulation of molecular mechanisms, among other factors. Hence, having knowledge of the role of molecular processes in the advancement of brain tumors is enlightening, and the current review specifically examines the role of autophagy. The discussion would focus on the molecular pathways that control autophagy in brain tumors, and its dual role as a tumor suppressor and a supporter of tumor survival. Autophagy can control the advancement of different types of brain tumors like glioblastoma, glioma, and ependymoma, demonstrating its potential for treatment. Autophagy mechanisms can influence metastasis and drug resistance in glioblastoma, and there is a complex interplay between autophagy and cellular responses to stress like hypoxia and starvation. Autophagy can inhibit the growth of brain tumors by promoting apoptosis. Hence, focusing on autophagy could offer fresh perspectives on creating successful treatments.

Sanguinarine suppresses oral squamous cell carcinoma progression by targeting the PKM2/TFEB aix to inhibit autophagic flux

BACKGROUND

Oral squamous cell carcinoma (OSCC) is one of the most common malignancies. However, there is no effective treatment for OSCC.

PURPOSE

This study aimed to identify a natural compound with significant efficacy against OSCC and elucidate its primary mechanism of action.

METHODS

An FDA-approved drug library and an MCE autophagy-related molecular compound library were screened through high-throughput screening to identify an effective natural compound against OSCC. The IC50 value of sanguinarine (Sang) in OSCC cells was determined using a CCK8 assay. Immunoblotting and immunofluorescence staining were used to assess the effect of Sang on autophagic flux in OSCC cells. Changes in the acidic lysosomal environment were evaluated using RFP-GFP-LC3B and LysoSensor Green DND-189. Furthermore, limited proteolysis-coupled mass spectrometry (LiP-MS) and virtual screening techniques were utilized to identify direct binding targets of Sang, which were subsequently validated by surface plasmon resonance (SPR) and microscale thermophoresis (MST). Molecular docking combined with molecular dynamics analysis identified the binding site between the target protein and Sang. In vitro and in vivo investigations with mutant plasmids confirmed this finding.

RESULTS

Screening led to the identification of the naturally occurring autophagy modulator Sang as a potent inhibitor of OSCC progression. Moreover, Sang impaired lysosomal function through reducing lysosomal-associated membrane proteins, inhibiting lysosomal proteolysis, and altering the lysosomal pH. These effects contributed to defects in autophagic clearance and subsequently suppressed OSCC progression. Notably, Sang bound the phenylalanine 26 (F26) residue in pyruvate kinase M2 (PKM2) and inhibited PKM2 enzymatic activity, subsequently suppressing transcription factor EB (TFEB) expression to inhibit lysosomal function and blocking autophagic flux in OSCC cells.

CONCLUSION

Our results demonstrate for the first time that Sang can suppress the PKM2/TFEB axis, and influence lysosomal function, thereby blocking autophagy and inhibiting the progression of OSCC, making it a promising therapeutic option for the treatment of OSCC.

Autophagy in cancer development, immune evasion, and drug resistance

Macroautophagy/autophagy is a highly conserved evolutionary mechanism involving lysosomes for the degradation of cytoplasmic components including organelles. The constitutive, basal level of autophagy is fundamental for preserving cellular homeostasis; however, alterations in autophagy can cause disease pathogenesis, including cancer. The role of autophagy in cancer is particularly complicated, since this process acts both as a tumor suppressor in precancerous stages but facilitates tumor progression during carcinogenesis and later stages of cancer progression. This shift between anti-tumor and pro-tumor roles may be influenced by genetic and environmental factors modulating key pathways such as those involving autophagy-related proteins, the PI3K-AKT-MTOR axis, and AMPK, which often show dysregulation in tumors. Autophagy regulates various cellular functions, including metabolism of glucose, glutamine, and lipids, cell proliferation, metastasis, and several types of cell death (apoptosis, ferroptosis, necroptosis and immunogenic cell death). These multifaceted roles demonstrate the potential of autophagy to affect DNA damage repair, cell death pathways, proliferation and survival, which are critical in determining cancer cells' response to chemotherapy. Therefore, targeting autophagy pathways presents a promising strategy to combat chemoresistance, as one of the major reasons for the failure in cancer patient treatment. Furthermore, autophagy modulates immune evasion and the function of immune cells such as T cells and dendritic cells, influencing the tumor microenvironment and cancer's biological behavior. However, the therapeutic targeting of autophagy is complex due to its dual role in promoting survival and inducing cell death in cancer cells, highlighting the need for strategies that consider both the beneficial and detrimental effects of autophagy modulation in cancer therapy. Hence, both inducers and inhibitors of autophagy have been introduced for the treatment of cancer. This review emphasizes the intricate interplay between autophagy, tumor biology, and immune responses, offering insights into potential therapeutic approaches that deploy autophagy in the cancer suppression.

Free Cholesterol-Induced Liver Injury in Non-Alcoholic Fatty Liver Disease: Mechanisms and a Therapeutic Intervention Using Dihydrotanshinone I

Build-up of free cholesterol (FC) substantially contributes to the development and severity of non-alcoholic fatty liver disease (NAFLD). Here, we investigate the specific mechanism by which FC induces liver injury in NAFLD and propose a novel therapeutic approach using dihydrotanshinone I (DhT). Rather than cholesterol ester (CE), we observed elevated levels of total cholesterol, FC, and alanine transaminase (ALT) in NAFLD patients and high-cholesterol diet-induced NAFLD mice compared to those in healthy controls. The FC level demonstrated a positive correlation with the ALT level in both patients and mice. Mechanistic studies revealed that FC elevated reactive oxygen species level, impaired the function of lysosomes, and disrupted lipophagy process, consequently inducing cell apoptosis. We then found that DhT protected mice on an HCD diet, independent of gut microbiota. DhT functioned as a potent ligand for peroxisome proliferator-activated receptor α (PPARα), stimulating its transcriptional function and enhancing catalase expression to lower reactive oxygen species (ROS) level. Notably, the protective effect of DhT was nullified in mice with hepatic PPARα knockdown. Thus, these findings are the first to report the detrimental role of FC in NAFLD, which could lead to the development of new treatment strategies for NAFLD by leveraging the therapeutic potential of DhT and PPARα pathway.

Assessing Autophagy Flux in Glioblastoma Temozolomide Resistant Cells

Autophagy is a critical cellular process involved in the degradation and recycling of cytoplasmic components, playing a dual role in cancer by either promoting cell survival or facilitating cell death. In glioblastoma (GB), autophagy has been implicated in resistance to the chemotherapeutic agent temozolomide (TMZ). This study presents a novel method to accurately measure autophagy flux in TMZ-resistant glioblastoma cells, combining advanced imaging techniques with biochemical assays. By quantifying key autophagy markers such as LC3-II and SQSTM1, our approach provides detailed insights into the dynamic processes of autophagosome formation and clearance under therapeutic stress. This method advances our understanding of autophagy in GB chemoresistance and has significant implications for the development of autophagy-targeted therapies. The ability to monitor and manipulate autophagy flux in real time offers a promising avenue for monitoring and understanding TMZ resistance and improving patient outcomes in glioblastoma treatment.

Antioxidant, Anti-Inflammatory, and Anticancer Activities of Five Citrus Peel Essential Oils

Citrus peel essential oil (CPEO) is favored by people for its aromatic scent, while also possessing numerous bioactive compounds that are advantageous to human health. This study evaluated the antioxidant, anti-inflammatory, and anticancer activities of CPEOs through cell experiments. The results showed that CPEOs could increase the activity of the antioxidant enzyme system and nonenzymatic defence system in H2O2-treated RAW 264.7 cells by reducing cellular lipid peroxidation. CPEOs also reduced the nitric oxide production induced by lipopolysaccharide treatment in RAW 264.7 cells while decreasing proinflammatory cytokines expression and increasing anti-inflammatory cytokine expression. Wound healing assays, flow cytometry, and quantitative real-time fluorescent quantitative PCR (qRT-PCR) revealed that CPEOs could induce apoptosis in U87 cells through the mitochondrial apoptotic pathway. These findings indicate that CPEOs possess excellent antioxidant, anti-inflammatory, and anticancer activity potential, making them suitable for use in functional antioxidant and anti-inflammatory foods and nutritional health products.

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.

Towards precision medicine: design considerations for nanozymes in tumor treatment

Since the discovery of Fe3O4 nanoparticles with enzyme-like activity in 2007, nanozymes have emerged as a promising class of catalysts, offering advantages such as high catalytic efficiency, low cost, mild reaction conditions, and excellent stability. These properties make nanozymes highly suitable for large-scale production. In recent years, the convergence of nanomedicine and nanocatalysis has highlighted the potential of nanozymes in diagnostic and therapeutic applications, particularly in tumor therapy. Despite these advancements, the clinical translation of nanozymes remains hindered by the lack of designs tailored to specific tumor characteristics, limiting their effectiveness in targeted therapy. This review addresses the mechanisms by which nanozymes induce cell death in various tumor types and emphasizes the key design considerations needed to enhance their therapeutic potential. By identifying the challenges and opportunities in the field, this study aims to provide a foundation for future nanozyme development, ultimately contributing to more precise and effective cancer treatments.

Structural characterization of Hericium coralloides polysaccharide and its neuroprotective function in Alzheimer's disease

Alzheimer's disease (AD) is a common neurodegenerative disorder. Polysaccharides have been scientifically demonstrated to possess neuroprotective properties. In this study, a polysaccharide was isolated from the fruiting bodies of Hericium coralloides using hot water extraction and purified using column chromatography. This H. coralloides polysaccharide (HCP) is a galactan with a main chain of →6)-α-d-Galp-(1 → and a molecular weight of 16.06 kDa. The partial α-l-Fucp-(1 → substitution takes place at its O-2 position. The neuroprotective effects of HCP were investigated in an APP/PS1 mouse model of Alzheimer's disease. The step-down and Morris water maze tests demonstrated that HCP effectively ameliorated cognitive impairment. After 8-week treatment, HCP reduced amyloid-β plaques and phosphorylated tau protein deposition. In combination with the gut microbiota and metabolites, proteomic analysis suggested that the neuroprotective effects of HCP are associated with neuroinflammation and autophagy. Immunofluorescence and western blotting analyses confirmed that HCP facilitated the polarization of M2 microglia by augmenting autophagy flux, thereby effectively reducing levels of amyloid-β plaques and neuroinflammation. These data demonstrate that HCP effectively mitigates neuroinflammation by enhancing autophagic flux, demonstrating its potential for the treatment of AD.

Molecular pharmacology and therapeutic advances of monoterpene perillyl alcohol

BACKGROUND

Perillyl alcohol (POH) is a aroma monoterpene commonly obtained from various plants' essential oil. Recently, increasing researches have demonstrated that POH may be useful, not only as flavor compound, but also as bioactive molecule because of a variety of biological activities.

PURPOSE

The aim of this review is to summarize the production, pharmacological activities and molecular mechanism, active derivatives, toxicity and parmacokinetics, and industrial application of POH.

METHODS

A systematic search of published articles up to January 2024 in Web of Science, China Knowledge Network, and PubMed databases is conducted using the following keywords: POH, POH derivatives, biological or pharmacological, production or synthesis, pharmacokinetics, toxicity and application.

RESULTS

Biotechnological production is considered to be a potential alternative approach to generate POH. POH provides diverse pharmacological benefits, including anticancer, antimicrobial, insecticidal, antioxidant, anti-inflammatory, hypotensive, vasorelaxant, antinociceptive, antiasthmatic, hepatoprotective effects, etc. The underlying mechanisms of action include modulation of NF-κB, JNK/c-Jun, Notch, Akt/mTOR, PI3K/Akt/eNOS, STAT3, Nrf2 and ERS response pathways, mitigation of mitochondrial dysfunction and membrane integrity damage, and inhibition of ROS accumulation, pro-inflammatory cytokines release and NLRP3 activation. What's more, the proteins or genes influenced by POH against diseases refer to Bax, Bcl-2, cyclin D1, CDK, p21, p53, HIF-1α, AP-1, caspase-3, M6P/IGF2R, PARP, VEGF, etc. Some clinical studies report that intranasal delivery of POH is a safe and effective treatment for cancer, but further clinical investigations are needed to confirm other health benefits of POH in human healthy. Depending on these health-promoting properties together with desirable flavor and safety, POH can be employed as dietary supplement, preservative and flavor additive in food and cosmetic fields, as building block in synthesis fields, as anticancer drug in medicinal fields, and as pesticides and herbicides in agricultural fields.

CONCLUSION

This review systematically summarizes the recent advances in POH and highlights its therapeutic effects and potential mechanisms as well as the clinical settings, which is helpful to develop POH into functional food and new candidate drug for prevention and management of diseases. Future studies are needed to conduct more biological activity studies of POH and its derivatives, and check their clinical efficacy and potential side effects.

Daurisoline suppress glioma progression by inhibiting autophagy through PI3K/AKT/mTOR pathway and increases TMZ sensitivity

Glioma is one of the most common primary malignant tumors of the central nervous system. Temozolomide (TMZ) is the only effective chemotherapeutic agent, but it easily develops resistance and has unsatisfactory efficacy. Consequently, there is an urgent need to develop safe and effective compounds for glioma treatment. The cytotoxicity of 30 candidate compounds to glioma cells was detected by the CCK-8 assay. Daurisoline (DAS) was selected for further investigation due to its potent anti-glioma effects. Our study revealed that DAS induced glioma cell apoptosis through increasing caspase-3/6/9 activity. DAS significantly inhibited the proliferation of glioma cells by inducing G1-phase cell cycle arrest. Meanwhile, DAS remarkably suppressed the migration and invasion of glioma cells by regulating epithelial-mesenchymal transition. Mechanistically, our results revealed that DAS impaired the autophagic flux of glioma cells at a late stage by mediating the PI3K/AKT/mTOR pathway. DAS could inhibit TMZ-induced autophagy and then significantly promote TMZ chemosensitivity. Nude mice xenograft model revealed that DAS could restrain glioma proliferation and promote TMZ chemosensitivity. Thus, DAS is a potential anti-glioma drug that can improve glioma sensitivity to TMZ and provide a new therapeutic strategy for glioma in chemoresistance.

Temozolomide, Procarbazine and Nitrosoureas in the Therapy of Malignant Gliomas: Update of Mechanisms, Drug Resistance and Therapeutic Implications

The genotoxic methylating agents temozolomide (TMZ) and procarbazine and the chloroethylating nitrosourea lomustine (CCNU) are part of the standard repertoire in the therapy of malignant gliomas (CNS WHO grade 3 and 4). This review describes the mechanisms of their cytotoxicity and cytostatic activity through apoptosis, necroptosis, drug-induced senescence, and autophagy, interaction of critical damage with radiation-induced lesions, mechanisms of glioblastoma resistance to alkylating agents, including the alkyltransferase MGMT, mismatch repair, DNA double-strand break repair and DNA damage responses, as well as IDH-1 and PARP-1. Cyclin-dependent kinase inhibitors such as regorafenib, synthetic lethality using PARP inhibitors, and alternative therapies including tumor-treating fields (TTF) and CUSP9v3 are discussed in the context of alkylating drug therapy and overcoming glioblastoma chemoresistance. Recent studies have revealed that senescence is the main trait induced by TMZ in glioblastoma cells, exhibiting hereupon the senescence-associated secretory phenotype (SASP). Strategies to eradicate therapy-induced senescence by means of senolytics as well as attenuating SASP by senomorphics are receiving increasing attention, with therapeutic implications to be discussed.