A steroidal saponin form Paris vietnamensis (Takht.) reverses temozolomide resistance in glioblastoma cells via inducing apoptosis through ROS/PI3K/Akt pathway

Plant-derived nanovesicles: Promising therapeutics and drug delivery nanoplatforms for brain disorders

Plant-derived nanovesicles (PDNVs), including plant extracellular vesicles (EVs) and plant exosome-like nanovesicles (ELNs), are natural nano-sized membranous vesicles containing bioactive molecules. PDNVs consist of a bilayer of lipids that can effectively encapsulate hydrophilic and lipophilic drugs, improving drug stability and solubility as well as providing increased bioavailability, reduced systemic toxicity, and enhanced target accumulation. Bioengineering strategies can also be exploited to modify the PDNVs to achieve precise targeting, controlled drug release, and massive production. Meanwhile, they are capable of crossing the blood-brain barrier (BBB) to transport the cargo to the lesion sites without harboring human pathogens, making them excellent therapeutic agents and drug delivery nanoplatform candidates for brain diseases. Herein, this article provides an initial exposition on the fundamental characteristics of PDNVs, including biogenesis, uptake process, isolation, purification, characterization methods, and source. Additionally, it sheds light on the investigation of PDNVs' utilization in brain diseases while also presenting novel perspectives on the obstacles and clinical advancements associated with PDNVs.

Steroidal saponins: Natural compounds with the potential to reverse tumor drug resistance (Review)

Steroidal saponins are a type of natural product that have been widely used in Chinese herbal medicine, with a variety of pharmacological activities, such as antitumor, anti-inflammatory and anti-bacterial effects. Cancer has become a growing global health problem, and drug therapy is currently the most important clinical antitumor treatment. However, drug resistance is a major obstacle to the effectiveness of chemotherapy, resulting in >90% of deaths of patients with cancer receiving conventional chemotherapy. It has been found that steroidal saponins may exert an effect on the reversal of drug resistance in tumor cells by regulating apoptosis, autophagy, epithelial-mesenchymal transition and drug efflux through multiple related signaling pathways. The present study reviews the role and mechanism of steroidal saponins in the treatment of tumor drug resistance, aiming to provide a scientific basis and research ideas for the future development and clinical application of natural steroidal saponins.

Trillium tschonoskii rhizome saponin improves spatial learning and memory by enhancing neurovascular restorative in ischemic rats

BACKGROUND

Trillium tschonoskii rhizome saponins (TSTT) has been significantly effective in treating traumatic injury, neurasthenia, cancer and inflammatory diseases as a folk medicine. However, the mechanism regarding to TSTT induced the neurovascular restorative after ischemia is without fully elucidated.

PURPOSE

This research was constructed to study the value of TSTT in promoting endogenous repair of neurovascular and augmenting the ability of spatial study and memory retention in ischaemic rats.

STUDY DESIGN

The improvement of TSTT on cerebral infraction and perfusion was observed by magnetic resonance imaging (MRI) experiments and the molecular mechanisms were further explored.

METHODS

First, rats were ligated the middle cerebral artery to construct a permanent ischaemia model, subsequently intragastric injection administrated with TSTT (120, 60, 30 mg kg-1) at 6 h after operation, then once a day during next 30 days. Morris water maze was applied to observe the neurobehavioral changes. Multimodal MRI sequences were performed to monitoring brain injuries as well as cerebral blood flow. Histopathological staining was employed to evaluate the morphological changes of neurons. Transmission electron microscopy (TEM) was employed to detect the neurons, vascular structure, and synapse. Immunofluorescent staining was utilized to evaluate the endogenous repair progress. The axonal growth-inhibitors and axonal guidance cues were analyzed using western blotting.

RESULTS

Contrast to the model group, TSTT declined the infarction and elevated the parenchymal volume. Notably, treated with TSTT significantly decreased the ADC (ipsilateral/contralateral). In histopathologic examination, TSTT prominently boosted amounts of cortical and striatal nerve cells and protected ultrastructure of neurovascular unit. According with results of nuclear magnetic imaging, TSTT enhanced endogenous repair progress. Especially, TSTT treatments obviously inhibited protein levels of NogoA/NgR/RhoA/ROCK2, accompanied by increased expression of Netrin/DCC and Slit2/Robo1.

CONCLUSION

To sum up, our data illustrated that TSTT promoted cerebral reestablishment. The above result was in line with improving cerebral blood flow, elevated integrity of neurovascular structure, accelerating endogenous restoration and impairing the axonal growth inhibitors NogoA/NgR/RhoA/ROCK2 signaling, thereby improving poststroke learning and memory.

New Avenues and Major Achievements in Phytocompounds Research for Glioblastoma Therapy

Phytocompounds have been evaluated for their anti-glioblastoma actions for decades, with promising results from preclinical studies but only limited translation into clinics. Indeed, by targeting multiple signaling pathways deregulated in cancer, they often show high efficacy in the in vitro studies, but their poor bioavailability, low tumor accumulation, and rapid clearance compromise their efficacy in vivo. Here, we present the new avenues in phytocompound research for the improvement of glioblastoma therapy, including the ways to enhance the response to temozolomide using phytochemicals, the current focus on phytocompound-based immunotherapy, or the use of phytocompounds as photosensitizers in photodynamic therapy. Moreover, we present new, intensively evaluated approaches, such as chemical modifications of phytochemicals or encapsulation into numerous types of nanoformulations, to improve their bioavailability and delivery to the brain. Finally, we present the clinical trials evaluating the role of phytocompounds or phytocompound-derived drugs in glioblastoma therapy and the less studied phytocompounds or plant extracts that have only recently been found to possess promising anti-glioblastoma properties. Overall, recent advancements in phytocompound research are encouraging; however, only with more 3D glioblastoma models, in vivo studies, and clinical trials it is possible to upgrade the role of phytocompounds in glioblastoma treatment to a satisfactory level.

Cellular stress responses as modulators of drug cytotoxicity in pharmacotherapy of glioblastoma

Despite the extensive efforts to find effective therapeutic strategies, glioblastoma (GBM) remains a therapeutic challenge with dismal prognosis of survival. Over the last decade the role of stress responses in GBM therapy has gained a great deal of attention, since depending on the duration and intensity of these cellular programs they can be cytoprotective or promote cancer cell death. As such, initiation of the UPR, autophagy or oxidative stress may either impede or facilitate drug-mediated cell killing. In this review, we summarize the mechanisms that regulate ER stress, autophagy, and oxidative stress during GBM development and progression to later discuss the involvement of these stress pathways in the response to different treatments. We also discuss how a precise understanding of the molecular mechanisms regulating stress responses evoked by different pharmacological agents could decisively contribute to the design of novel and more effective combinational treatments against brain malignancies.

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.

Steroidal Saponins: Naturally Occurring Compounds as Inhibitors of the Hallmarks of Cancer

Cancer is a global health burden responsible for an exponentially growing number of incidences and mortalities, regardless of the significant advances in its treatment. The identification of the hallmarks of cancer is a major milestone in understanding the mechanisms that drive cancer initiation, development, and progression. In the past, the hallmarks of cancer have been targeted to effectively treat various types of cancers. These conventional cancer drugs have shown significant therapeutic efficacy but continue to impose unfavorable side effects on patients. Naturally derived compounds are being tested in the search for alternative anti-cancer drugs. Steroidal saponins are a group of naturally occurring compounds that primarily exist as secondary metabolites in plant species. Recent studies have suggested that steroidal saponins possess significant anti-cancer capabilities. This review aims to summarize the recent findings on steroidal saponins as inhibitors of the hallmarks of cancer and covers key studies published between the years 2014 and 2024. It is reported that steroidal saponins effectively inhibit the hallmarks of cancer, but poor bioavailability and insufficient preclinical studies limit their utilization.

The Role of Hypoxia and Cancer Stem Cells in Development of Glioblastoma

Glioblastoma multiform (GBM) is recognized as the most malignant brain tumor with a high level of hypoxia, containing a small population of glioblastoma stem like cells (GSCs). These GSCs have the capacity of self-renewal, proliferation, invasion and recapitulating the parent tumor, and are major causes of radio-and chemoresistance of GBM. Upregulated expression of hypoxia inducible factors (HIFs) in hypoxia fundamentally contributes to maintenance and progression of GSCs. Therefore, we thoroughly reviewed the currently acknowledged roles of hypoxia-associated GSCs in development of GBM. In detail, we recapitulated general features of GBM, especially GSC-related features, and delineated essential responses resulted from interactions between GSC and hypoxia, including hypoxia-induced signatures, genes and pathways, and hypoxia-regulated metabolic alterations. Five hypothesized GSC niches are discussed and integrated into one comprehensive concept: hypoxic peri-arteriolar niche of GSCs. Autophagy, another protective mechanism against chemotherapy, is also closely related to hypoxia and is a potential therapeutic target for GBM. In addition, potential causes of therapeutic resistance (chemo-, radio-, surgical-, immuno-), and chemotherapeutic agents which can improve the therapeutic effects of chemo-, radio-, or immunotherapy are introduced and discussed. At last, as a potential approach to reverse the hypoxic microenvironment in GBM, hyperbaric oxygen therapy (HBOT) might be an adjuvant therapy to chemo-and radiotherapy after surgery. In conclusion, we focus on demonstrating the important role of hypoxia on development of GBM, especially by affecting the function of GSCs. Important advantages have been made to understand the complicated responses induced by hypoxia in GBM. Further exploration of targeting hypoxia and GSCs can help to develop novel therapeutic strategies to improve the survival of GBM patients.

Therapeutic effects on cancer of the active ingredients in rhizoma paridis

Cancer is a major threat to human health, with high mortality and a low cure rate, continuously challenging public health worldwide. Extensive clinical application of traditional Chinese medicine (TCM) for patients with poor outcomes of radiotherapy and chemotherapy provides a new direction in anticancer therapy. Anticancer mechanisms of the active ingredients in TCM have also been extensively studied in the medical field. As a type of TCM against cancer, Rhizoma Paridis (Chinese name: Chonglou) has important antitumor effects in clinical application. The main active ingredients of Rhizoma Paridis (e.g., total saponins, polyphyllin I, polyphyllin II, polyphyllin VI, and polyphyllin VII) have shown strong antitumor activities in various cancers, such as breast cancer, lung cancer, colorectal cancer, hepatocellular carcinoma (HCC), and gastric cancer. Rhizoma Paridis also has low concentrations of certain other active ingredients with antitumor effects, such as saponins polyphyllin E, polyphyllin H, Paris polyphylla-22, gracillin, and formosanin-C. Many researchers have studied the anticancer mechanism of Rhizoma Paridis and its active ingredients. This review article describes research progress regarding the molecular mechanism and antitumor effects of the active ingredients in Rhizoma Paridis, suggesting that various active ingredients in Rhizoma Paridis may be potentially therapeutic against cancer.

Aspiletrein A Induces Apoptosis Cell Death via Increasing Reactive Oxygen Species Generation and AMPK Activation in Non-Small-Cell Lung Cancer Cells

Lung cancer remains a leading cause of death in cancer patients, and deregulation of apoptosis is a serious concern in clinical practice, even though therapeutic intervention has been greatly improved. Plants are a versatile source of biologically active compounds for anticancer drug discovery, and aspiletrein A (AA) is a steroidal saponin isolated from Aspidistra letreae that has a potent cytotoxic effect on various cancer cell lines. In this study, we investigated and determined the underlying molecular mechanism by which AA induces apoptosis. AA strongly induced apoptosis in NSCLC cells by mediating ROS generation and thereby activating AMP-activated protein kinase (AMPK) signaling. Consequently, downstream signaling and levels of phosphorylated mTOR and Bcl-2 were significantly decreased. Pretreatment with either an antioxidant, N-acetylcysteine, or an AMPK inhibitor, compound C, could reverse the apoptosis-inducing effect and counteract the effect of AA on the AMPK signaling pathway. Decreased levels of Bcl-2 were due to AA-mediating Bcl-2 degradation via a ROS/AMPK/mTOR axis-dependent proteasomal mechanism. Consistently, the apoptotic-inducing effect of AA was also observed in patient-derived malignant lung cancer cells, and it suppressed an in vitro 3D-tumorigenesis. This study identified the underlying mechanism of AA on lung cancer apoptosis, thereby facilitating potential research and development of this compound for further clinical implications.

Current perspectives on naturally occurring saponins as anticancer agents

Saponins, a heterogeneous group of sterol and triterpene glycosides, are distributed widely in nature. Naturally occurring saponins could act on diverse targets in cancer cells and consequently exert potential antiproliferative effects in various cancers, including drug-resistant forms. Therefore, naturally occurring saponins are useful templates for the discovery of novel anticancer candidates. Covering articles published between January 2020 and October 2021, this review aims to outline the recent development of naturally occurring steroidal and triterpenoidal saponins with anticancer potential to provide novel anticancer lead hits/candidates.

Naturally occurring steroidal saponins as potential anticancer agents: Current developments and mechanisms of action

Cancer is claimed as a prevalent cause of mortality throughout the world. Conventional chemotherapy plays a pivotal role in the treatment of cancers, but the multidrug resistance has already become one of the major impediments for efficacious cancer therapy, creating a great demand for the development of novel anticancer drugs. Steroidal saponins, abundantly found in nature, possess extensive structural variability, and some naturally occurring steroidal saponins exhibited profound anticancer properties through a variety of pathways. Hence, naturally occurring steroidal saponins are powerful lead compounds/candidates in the development of novel therapeutic agents. This review article described the recent progress in naturally occurring steroidal saponins as potential anticancer agents, and the mechanisms of action were also discussed, covering articles published between 2017 and 2021.

Saponins -Uptake and Targeting issues for brain-specific delivery for enhanced cell death induction in glioblastoma

Abstract:

Saponins represent a category of diverse, natural glycoside molecules that belong to the triterpenoid or the steroid class. They vary in terms of their solubility and permeability characteristics and are classifiable based on the biopharmaceutics classification system. They have drug delivery potential as surfactants that can solubilize cholesterol in the plasma membrane of tumorigenic cells. Glioblastoma is an important malignancy that can aggressively afflict the brain of humans with a poor prognosis. Glioblastoma Stem Cells (GSCs), are an important subset of cancer cells and are major determinants for drug resistance and tumour relapse. These cells are quiescent and have been known to survive current therapeutic strategies. Certain saponins have shown potential to eliminate glioblastoma cells in a variety of model systems and hence provide a sound scientific basis for their development as a “stand-alone” drug or as part of a drug combination (from the existing arsenal of drugs) developed for the treatment of glioblastoma. However, due to their reactogenicity towards the immune system and hemolytic potential, selective delivery to the tumorigenic site is essential. Hence, nano-formulations (liposome/emulsion-based delivery systems/nano-structured lipid and calix[n]arenes-based carriers) and variants that are resistant to saponin may serve as delivery tools that can be functionalized to improve the selectivity. It is necessary to develop/validate/refine in vitro higher order models that replicate the features of the glioma microenvironment (BBB/BTB). Reproducible validation of the model as well as the drug/delivery system will help in the development of formulations that can augment cell death in this recalcitrant brain tumour.

Hepatoprotective role of peroxisome proliferator-activated receptor-α in non-cancerous hepatic tissues following transcatheter arterial embolization

Transcatheter arterial embolization (TAE) is a widely used technique in treating hepatic carcinoma but may cause liver injury in some cases. This study investigated the hepatoprotective effect of the preprocessed peroxisome proliferator-activated receptor-α (PPAR-α) agonist-WY-14643 following TAE. A total of 60 rabbit liver cancer models were developed and divided into a combined treatment (WY-14643 and TAE), TAE, and control groups. After TAE, we examined the histopathological picture and liver functions. Further, the expression of antioxidant enzymes, tumor necrosis factor-α (TNF-α), nuclear factor of κ-light chain of enhancer-activated B cells (NF-κB), PPAR-α, and B-cell lymphoma-2 (Bcl-2) was analyzed. Liver function tests, pathology score, and apoptosis index significantly worsened in the TAE group but were normalized in the combined treatment group. In addition, ELISA results showed that antioxidant enzyme activity significantly increased, while the malondialdehyde content and level of inflammatory cytokines were significantly reduced in the combined treatment group. Furthermore, compared to the TAE group, the expressions of PPAR-α, antioxidant enzymes superoxide dismutase1 (SOD1) and SOD2, and Bcl-2 were significantly elevated, while NF-κB was significantly reduced in the combined treatment group. On the other hand, the expression of NF-κB in tumor tissues was significantly reduced by pretreatment with WY-14643. Therefore, PPAR-α can ameliorate liver injury by exerting its anti-oxidative, anti-inflammatory, and anti-apoptotic functions.

CN-3 increases TMZ sensitivity and induces ROS-dependent apoptosis and autophagy in TMZ-resistance glioblastoma

Many glioma patients develop resistance to temozolomide (TMZ) treatment, resulting in reduced efficacy and survival rates. TMZ-resistant cell lines SHG44R and U87R, which highly express O₆ -methylguanine DNA methyltransferase (MGMT) and P-gp, were established. CN-3, a new asterosaponin, showed cytotoxic effects on TMZ-resistant cells in a dose- and time-dependent manner via reactive oxygen species (ROS)-mediated apoptosis and autophagy. Transmission electron microscopy and monodansylcadaverine (MDC) staining showed turgidity of the mitochondria and autophagosomes in CN-3-treated SHG44R and U87R cells. The autophagy inhibitor 3-methyladenine was used to confirm the important role of autophagy in CN-3 cytotoxicity in TMZ-resistant cells. The ROS scavenger N-acetyl- l-cysteine (NAC) attenuated the levels of ROS induced by CN-3 and, therefore, rescued the CN-3 cytotoxic effect on the viability of SHG44R and U87R cells by Cell Counting Kit-8 assays and JuLI-Stage videos. MDC staining also confirmed that NAC rescued an autophagosome increase in CN-3-treated SHG44R and U87R cells. Western blotting revealed that CN-3 increased Bax, cleaved-caspase 3, cytochrome C, PARP-1, LC3-Ⅱ, and Beclin1, and decreased P-AKT, Bcl-2, and p62. Further rescue experiments revealed that CN-3 induced apoptosis and autophagy through ROS-mediated cytochrome C, cleaved-caspase 3, Bcl-2, P-AKT, PARP-1, and LC3-Ⅱ. In addition, CN-3 promoted SHG44R and U87R cells sensitive to TMZ by reducing the expression of P-gp, MGMT, and nuclear factor kappa B p65, and it had a synergistic cytotoxic effect with TMZ. Moreover, CN-3 disrupted the natural cycle arrest and inhibited the migration of SHG44R and U87R cells by promoting cyclin E1 and D1, and by decreasing P21, P27, N-cadherin, β-catenin, transforming growth factor beta 1, and Smad2.

Antioxidant responses related to temozolomide resistance in glioblastoma

Glioblastoma remains one of the most challenging and devastating cancers, with only a very small proportion of patients achieving 5-year survival. The current standard of care consists of surgery, followed by radiation therapy with concurrent and maintenance chemotherapy with the alkylating agent temozolomide. To date, this drug is the only one that provides a significant survival benefit, albeit modest, as patients end up acquiring resistance to this drug. As a result, tumor progression and recurrence inevitably occur, leading to death. Several factors have been proposed to explain this resistance, including an upregulated antioxidant system to keep the elevated intracellular ROS levels, a hallmark of cancer cells, under control. In this review, we discuss the mechanisms of chemoresistance -including the important role of glioblastoma stem cells-with emphasis on antioxidant defenses and how agents that impair redox balance (i.e.: sulfasalazine, erastin, CB-839, withaferin, resveratrol, curcumin, chloroquine, and hydroxychloroquine) might be advantageous in combined therapies against this type of cancer.

Natural Compounds in Glioblastoma Therapy: Preclinical Insights, Mechanistic Pathways, and Outlook

Simple Summary

Glioblastoma (GBM) is a tumor of the brain or spinal cord with poor clinical prognosis. Current interventions, such as chemotherapy and surgical tumor resection, are constrained by tumor invasion and cancer drug resistance. Dietary natural substances are therefore evaluated for their potential as agents in GBM treatment. Various substances found in fruits, vegetables, and other natural products restrict tumor growth and induce GBM cell death. These preclinical effects are promising but remain constrained by natural substances’ varying pharmacological properties. While many of the reviewed substances are available as over-the-counter supplements, their anti-GBM efficacy should be corroborated by clinical trials moving forward.

Abstract

Glioblastoma (GBM) is an aggressive, often fatal astrocyte-derived tumor of the central nervous system. Conventional medical and surgical interventions have greatly improved survival rates; however, tumor heterogeneity, invasiveness, and chemotherapeutic resistance continue to pose clinical challenges. As such, dietary natural substances—an integral component of the lifestyle medicine approach to chronic diseases—are examined as potential chemotherapeutic agents. These heterogenous substances exert anti-GBM effects by upregulating apoptosis and autophagy, inducing cell cycle arrest, interfering with tumor metabolism, and inhibiting proliferation, neuroinflammation, chemoresistance, angiogenesis, and metastasis. Although these beneficial effects are promising, natural substances’ efficacy in GBM is constrained by their bioavailability and blood–brain barrier permeability; various chemical formulations are proposed to improve their pharmacological properties. Many of the reviewed substances are available as over-the-counter dietary supplements, underscoring their viability as lifestyle interventions. However, clinical trials remain necessary to substantiate the in vitro and in vivo properties of natural substances.