Gambogic Acid as a Candidate for Cancer Therapy: A Review

Gambogic acid exhibits promising anticancer activity by inhibiting the pentose phosphate pathway in lung cancer mouse model

BACKGROUND

The pentose phosphate pathway (PPP) plays a crucial role in the material and energy metabolism in cancer cells. Targeting 6-phosphogluconate dehydrogenase (6PGD), the rate-limiting enzyme in the PPP metabolic process, to inhibit cellular metabolism is an effective anticancer strategy. In our previous study, we have preliminarily demonstrated that gambogic acid (GA) induced cancer cell death by inhibiting 6PGD and suppressing PPP at the cellular level. However, it is unclear whether GA could suppress cancer cell growth by inhibiting PPP pathway in mouse model.

PURPOSE

This study aimed to confirm that GA as a covalent inhibitor of 6PGD protein and to validate that GA suppresses cancer cell growth by inhibiting the PPP pathway in a mouse model.

METHODS

Cell viability was detected by CCK-8 assays as well as flow cytometry. The protein targets of GA were identified using a chemical probe and activity-based protein profiling (ABPP) technology. The target validation was performed by in-gel fluorescence assay, the Cellular Thermal Shift Assay (CETSA). A lung cancer mouse model was constructed to test the anticancer activity of GA. RNA sequencing was performed to analyze the global effect of GA on gene expression.

RESULTS

The chemical probe of GA exhibited high biological activity in vitro. 6PGD was identified as one of the binding proteins of GA by ABPP. Our findings revealed a direct interaction between GA and 6PGD. We also found that the anti-cancer activity of GA depended on reactive oxygen species (ROS), as evidenced by experiments on cells with 6PGD knocked down. More importantly, GA could effectively reduce the production of the two major metabolites of the PPP in lung tissue and inhibit cancer cell growth in the mouse model. Finally, RNA sequencing data suggested that GA treatment significantly regulated apoptosis and hypoxia-related physiological processes.

CONCLUSION

These results demonstrated that GA was a covalent inhibitor of 6PGD protein. GA effectively suppressed cancer cell growth by inhibiting the PPP pathway without causing significant side effects in the mouse model. Our study provides in vivo evidence that elucidates the anticancer mechanism of GA, which involves the inhibition of 6PGD and modulation of cellular metabolic processes.

Natural gambogic acid-tuned self-assembly of nanodrugs towards synergistic chemophototherapy against breast cancer

Gambogic acid (GA) as a naturally derived chemotherapeutic agent is of increasing interest for antitumor therapy. However, current research mainly focuses on improving the pharmacological properties to overcome the shortcomings in clinical applications or as a synergistic anticancer agent in combination with chemotherapy and chemophototherapy. Yet, the material properties of GA (e.g., self-assembly) are often neglected. Herein, we validated the self-assembly function of GA and its huge potential as a single-component active carrier for synergistic delivery using pyropheophorbide-a (PPa) as a drug model. The results showed that self-assembled GA drives the formation of nano-GA/PPa mainly through noncovalent interactions such as π-π stacking, hydrophobic interactions, and hydrogen bonding. Additionally, although no significant differences in cytotoxicity were found between the individual in vitro chemotherapy and combined chemophototherapy, the as-prepared nano-GA/PPa exhibits remarkably improved water solubility and multiple favorable therapeutic features, leading to a prominent in vivo photochemotherapy efficiency of 89.3% inhibition rate with reduced hepatotoxicity of GA. This work highlights the potential of self-assembled GA as a drug delivery carrier for synergistic biomedical applications.

pH/GSH dual-responsive nanoparticle for auto-amplified tumor therapy of breast cancer

Breast cancer remains a malignancy that poses a serious threat to human health worldwide. Chemotherapy is one of the most widely effective cancer treatments in clinical practice, but it has some drawbacks such as poor targeting, high toxicity, numerous side effects, and susceptibility to drug resistance. For auto-amplified tumor therapy, a nanoparticle designated GDTF is prepared by wrapping gambogic acid (GA)-loaded dendritic porous silica nanoparticles (DPSNs) with a tannic acid (TA)-Fe(III) coating layer. GDTF possesses the properties of near-infrared (NIR)-enhanced and pH/glutathione (GSH) dual-responsive drug release, photothermal conversion, GSH depletion and hydroxyl radical (·OH) production. When GDTF is exposed to NIR laser irradiation, it can effectively inhibit cell proliferation and tumor growth both in vitro and in vivo with limited toxicity. This may be due to the synergistic effect of enhanced tumor accumulation, and elevated reactive oxygen species (ROS) production, GSH depletion, and TrxR activity reduction. This study highlights the enormous potential of auto-amplified tumor therapy.

Application of natural products in regulating ferroptosis in human diseases

BACKGROUND

Ferroptosis is a type of cell death caused by excessive iron-induced peroxidation. It has been found to be involved in a variety of diseases, and natural products can be used to target ferroptosis in treatments. Natural products are biologically active compounds extracted or synthesized from nature. It is an important resource for the discovery of skeletons with a high degree of structural diversity and a wide range of bioactivities, which can be developed directly or used as a starting point for the optimization of new drugs.

PURPOSE

In this review, we aim to discuss the interactions between natural products and ferroptosis in the treatment of human diseases.

METHODS

Literature was searched in Pubmed, Science Direct, and Web of Science databases for the 11-year period from 2012 to 2023 using the search terms "natural products", "ferroptosis", "human disease", "neurodegenerative disease", "cardiovascular disease", and "cancer".

RESULTS

In this research, the roles of natural products and ferroptosis were investigated. We suggest that natural products, such as terpenoids, flavonoids, polyphenols, alkaloids, and saponins, can be used in therapeutic applications for human diseases, as well as in ferroptosis. Additionally, the main mechanisms of ferroptosis were summarized and discussed. Furthermore, we propose that natural products can be utilized to enhance the sensitivity of cancer cells to ferroptosis, thus helping to overcome drug resistance and inhibit metastasis. Moreover, natural products have the potential to modulate the expression levels of ferroptosis-related factors. Finally, the future directions of this field were highlighted.

CONCLUSION

The potential of natural products which focus on ferroptosis to treat human illnesses, particularly cancer, is very encouraging for human wellbeing.

Multifunctional Biomimetic Liposomes with Improved Tumor-Targeting for TNBC Treatment by Combination of Chemotherapy, Antiangiogenesis and Immunotherapy

Triple negative breast cancer (TNBC) featuring high relapses and metastasis shows limited clinical therapeutic efficiency with chemotherapy for the extremely complex tumor microenvironment, especially angiogenesis and immunosuppression. Combination of antiangiogenesis and immunotherapy holds promise for effective inhibition of tumor proliferation and invasion, while it remains challenging for specific targeting drug delivery to tumors and metastatic lesions. Here, a multifunctional biomimetic liposome loading Gambogic acid (G/R-MLP) is developed using Ginsenoside Rg3 (Rg3) to substitute cholesterol and cancer cell membrane coating, which is designed to increase long-circulating action by a low immunogenicity and specifically deliver gambogic acid (GA) to tumor site and metastatic lesions by homologous targeting and glucose transporter targeting. After G/R-MLP accumulates in the primary tumors and metastatic nodules, it synergistically enhances the antitumor efficacy of GA, effectively suppressing the tumor growth and lung metastasis by killing tumor cells, inhibiting tumor cell migration and invasion, achieving antiangiogenesis and improving the antitumor immunity. All in all, the strategy combining chemotherapy, antiangiogenesis, and immunotherapy improves therapeutic efficiency and prolonged survival, providing a new perspective for the clinical treatment of TNBC.

Unveiling Gambogenic Acid as a Promising Antitumor Compound: A Review

Gambogenic acid is a derivative of gambogic acid, a polyprenylated xanthone isolated from Garcinia hanburyi. Compared with the more widely studied gambogic acid, gambogenic acid has demonstrated advantages such as a more potent antitumor effect and less systemic toxicity than gambogic acid according to early investigations. Therefore, the present review summarizes the effectiveness and mechanisms of gambogenic acid in different cancers and highlights the mechanisms of action. In addition, drug delivery systems to improve the bioavailability of gambogenic acid and its pharmacokinetic profile are included. Gambogenic acid has been applied to treat a wide range of cancers, such as lung, liver, colorectal, breast, gastric, bladder, and prostate cancers. Gambogenic acid exerts its antitumor effects as a novel class of enhancer of zeste homolog 2 inhibitors. It prevents cancer cell proliferation by inducing apoptosis, ferroptosis, and necroptosis and controlling the cell cycle as well as autophagy. Gambogenic acid also hinders tumor cell invasion and metastasis by downregulating metastasis-related proteins. Moreover, gambogenic acid increases the sensitivity of cancer cells to chemotherapy and has shown effects on multidrug resistance in malignancy. This review adds insights for the prevention and treatment of cancers using gambogenic acid.

Natural-product-based, carrier-free, noncovalent nanoparticles for tumor chemo-photodynamic combination therapy

Cancer, with its diversity, heterogeneity, and complexity, is a significant contributor to global morbidity, disability, and mortality, highlighting the necessity for transformative treatment approaches. Photodynamic therapy (PDT) has aroused continuous interest as a viable alternative to conventional cancer treatments that encounter drug resistance. Nanotechnology has brought new advances in medicine and has shown great potential in drug delivery and cancer treatment. For precise and efficient therapeutic utilization of such a tumor therapeutic approach with high spatiotemporal selectivity and minimal invasiveness, the carrier-free noncovalent nanoparticles (NPs) based on chemo-photodynamic combination therapy is essential. Utilizing natural products as the foundation for nanodrug development offers unparalleled advantages, including exceptional pharmacological activity, easy functionalization/modification, and well biocompatibility. The natural-product-based, carrier-free, noncovalent NPs revealed excellent synergistic anticancer activity in comparison with free photosensitizers and free bioactive natural products, representing an alternative and favorable combination therapeutic avenue to improve therapeutic efficacy. Herein, a comprehensive summary of current strategies and representative application examples of carrier-free noncovalent NPs in the past decade based on natural products (such as paclitaxel, 10-hydroxycamptothecin, doxorubicin, etoposide, combretastatin A4, epigallocatechin gallate, and curcumin) for tumor chemo-photodynamic combination therapy. We highlight the insightful design and synthesis of the smart carrier-free NPs that aim to enhance PDT efficacy. Meanwhile, we discuss the future challenges and potential opportunities associated with these NPs to provide new enlightenment, spur innovative ideas, and facilitate PDT-mediated clinical transformation.

New Salicylanilide Derivatives and Their Peptide Conjugates as Anticancer Compounds: Synthesis, Characterization, and In Vitro Effect on Glioblastoma

Pharmacologically active salicylanilides (2-hydroxy-N-phenylbenzamides) have been a promising area of interest in medicinal chemistry-related research for quite some time. This group of compounds has shown a wide spectrum of biological activities, including but not limited to anticancer effects. In this study, substituted salicylanilides were chosen to evaluate the in vitro activity on U87 human glioblastoma (GBM) cells. The parent salicylanilide, salicylanilide 5-chloropyrazinoates, a 4-aminosalicylic acid derivative, and the new salicylanilide 4-formylbenzoates were chemically and in vitro characterized. To enhance the internalization of the compounds, they were conjugated to delivery peptides with the formation of oxime bonds. Oligotuftsins ([TKPKG]n, n = 1-4), the ligands of neuropilin receptors, were used as GBM-targeting carrier peptides. The in vitro cellular uptake, intracellular localization, and penetration ability on tissue-mimicking models of the fluorescent peptide derivatives were determined. The compounds and their peptide conjugates significantly decreased the viability of U87 glioma cells. Salicylanilide compound-induced GBM cell death was associated with activation of autophagy, as characterized by immunodetection of autophagy-related processing of light chain 3 protein.

Induction of ferroptosis by natural phenols: A promising strategy for cancer therapy

In recent years, heightened interest surrounds the exploration of natural phenols as potential agents for cancer therapy, specifically by inducing ferroptosis, a unique form of regulated cell death characterized by iron-dependent lipid peroxidation. This review delves into the roles of key natural phenols, flavonoids, phenolic acids, curcumin, and stilbenes, in modulating ferroptosis and their underlying mechanisms. Emphasizing the significance of amino acid, lipid, and iron metabolism, the study elucidates the diverse pathways through which these phenols regulate ferroptosis. Notably, curcumin, a well-known polyphenol, exhibits multifaceted interactions with cellular components involved in ferroptosis regulation, providing a distinctive therapeutic avenue. Stilbenes, another phenolic class, demonstrate promising potential in influencing lipid metabolism and iron-dependent processes, contributing to ferroptotic cell death. Understanding the intricate interplay between these natural phenols and ferroptosis not only illuminates complex cellular regulatory networks but also unveils potential avenues for novel cancer therapies. Exploring these compounds as inducers of ferroptosis presents a promising strategy for targeted cancer treatment, capitalizing on the delicate balance between cellular metabolism and regulated cell death mechanisms. This article synthesizes current knowledge, aiming to stimulate further research into the therapeutic potential of natural phenols in the context of ferroptosis-mediated cancer therapy.

Thermal Proteome Profiling Strategy Identifies CNPY3 as a Cellular Target of Gambogic Acid for Inducing Prostate Cancer Pyroptosis

There is an urgent requirement to acquire a comprehensive comprehension of novel therapeutic targets for prostate cancer to facilitate the development of medications with innovative mechanisms. In this study, we identified gambogic acid (GBA) as a specific pyroptosis inducer in prostatic cancer cells. By using a thermal proteome profiling (TPP) strategy, we revealed that GBA induces pyroptosis by directly targeting the canopy FGF signaling regulator (CNPY3), which was previously considered "undruggable". Moreover, through the utilization of the APEX2-based proximity labeling method, we found that GBA recruited delactatease SIRT1, resulting in the elimination of lysine lactylation (Kla) on CNPY3. Of note, SIRT1-mediated delactylation influenced the cellular localization of CNPY3 to promote lysosome rupture for triggering pyroptosis. Taken together, our study identified CNPY3 as a distinctive cellular target for pyroptosis induction and its potential application in prostate cancer therapy.

Mechanism of gambogic acid repressing invasion and metastasis of colorectal cancer by regulating macrophage polarization via tumor cell-derived extracellular vesicle-shuttled miR-21

Colorectal cancer (CRC) is a major cause of mortality and morbidity. Gambogic acid (GA) is a promising antitumor drug for treating CRC. We aimed to elucidate its mechanism in CRC invasion/metastasis via tumor cell-derived extracellular vesicle (EV)-carried miR-21. Nude mice peritoneal carcinomatosis (PC) model was subjected to GA treatment liver collection, followed by observation/counting of metastatic liver tissues/liver metastatic nodules by hematoxylin and eosin staining. miR-21 expression in metastatic liver tissues/CD68 + CD86, CD68 + CD206 cell percentages and M2 macrophage marker CD206 level in tumor tissues/interleukin (IL)-12 and IL-10 levels were determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR)/flow cytometry/enzyme-linked immunosorbent assay. HT-29 cells were treated with GA/miR-21 mimics/negative control for 48 h. miR-21 expression/cell proliferation/migration/invasion/apoptosis were assessed by RT-qPCR/cell counting kit-8/scratch assay/transwell assay/flow cytometry. EVs were extracted from HT-29 cells and identified by transmission electron microscope/nanoparticle tracking analysis/Western blot. IL-4/IL-13-induced macrophages/PC nude mice were treated with GA and EVs, with the internalization of EVs by macrophages assessed through the uptake test. After intraperitoneal injection of GA, PC nude mice exhibited decreased tumor cell density/irregular cell number/liver metastatic nodule number/miR-21 expression, and CRC cells manifested reduced CD68 + CD206 cells/IL-10/miR-21/proliferation/migration/invasion and increased CD68 + CD86 cells/IL-12/apoptosis, while these trends were opposite after miR-21 overexpression, implying that GA curbed CRC/cell invasion/metastasis and macrophage polarization by diminishing miR-21 levels. miR-21 was encapsulated in HT-29 cell-derived EVs. M2 polarization elevated CD206 cells/IL-10, which were decreased by simultaneous GA treatment. EVs could be uptaken by macrophages. CRC cell-EV-miR-21 annulled the suppression effects of GA on macrophage M2 polarization. GA suppressed macrophage M2 polarization by lessening tumor cell derived-EV-shuttled miR-21, thereby weakening CRC invasion/metastasis.

Research progress on traditional Chinese medicine-induced apoptosis signaling pathways in ovarian cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

As a "silent killer" that threatens women's lives and health, ovarian cancer (OC) has the clinical characteristics of being difficult to detect, difficult to treat, and high recurrence. Traditional Chinese medicine (TCM) can be utilized as a long-term complementary and alternative therapy since it has shown benefits in alleviating clinical symptoms of OC, decreasing toxic side effects of radiation and chemotherapy, as well as enhancing patients' quality of life.

AIM OF THE REVIEW

This paper reviews how TCM contributes to the apoptosis of OC cells through signaling pathways, including active constituents, extracts, and herbal formulas, with the aim of providing a basis for the development and clinical application of therapeutic strategies for TCM in OC.

METHODS

The search was conducted from scientific databases PubMed, Embase, Web of Science, CNKI, Wanfang, VIP, and SinoMed databases aiming to elucidate the apoptosis signaling pathways in OC cells by TCM. The articles were searched by the keywords "ovarian cancer", "apoptosis", "signaling pathway", "traditional Chinese medicine", "Chinese herbal monomer", "Chinese herbal extract", and "herbal formula". The search was conducted from January 2013 to June 2023. A total of 97 potentially relevant articles were included, including 93 articles on Chinese medicine active constituents or extracts and 4 articles on Chinese herbal compound prescriptions.

RESULTS

TCM can induce apoptosis in OC cells by regulating signaling pathways with obvious advantages, including STAT3, PI3K/AKT, Wnt/β-catenin, MAPK, NF-κB, Nrf2, HIF-1α, Fas/Fas L signaling pathway, etc. CONCLUSION: Chinese medicine can induce apoptosis in OC cells through multiple pathways, targets, and routes. TCM has special advantages for treating OC, providing more reasonable evidence for the research and development of new apoptosis inducers.

Functionalized Nanomaterials for Inhibiting ATP-Dependent Heat Shock Proteins in Cancer Photothermal/Photodynamic Therapy and Combination Therapy

Phototherapies induced by photoactive nanomaterials have inspired and accentuated the importance of nanomedicine in cancer therapy in recent years. During these light-activated cancer therapies, a nanoagent can produce heat and cytotoxic reactive oxygen species by absorption of light energy for photothermal therapy (PTT) and photodynamic therapy (PDT). However, PTT is limited by the self-protective nature of cells, with upregulated production of heat shock proteins (HSP) under mild hyperthermia, which also influences PDT. To reduce HSP production in cancer cells and to enhance PTT/PDT, small HSP inhibitors that can competitively bind at the ATP-binding site of an HSP could be employed. Alternatively, reducing intracellular glucose concentration can also decrease ATP production from the metabolic pathways and downregulate HSP production from glucose deprivation. Other than reversing the thermal resistance of cancer cells for mild-temperature PTT, an HSP inhibitor can also be integrated into functionalized nanomaterials to alleviate tumor hypoxia and enhance the efficacy of PDT. Furthermore, the co-delivery of a small-molecule drug for direct HSP inhibition and a chemotherapeutic drug can integrate enhanced PTT/PDT with chemotherapy (CT). On the other hand, delivering a glucose-deprivation agent like glucose oxidase (GOx) can indirectly inhibit HSP and boost the efficacy of PTT/PDT while combining these therapies with cancer starvation therapy (ST). In this review, we intend to discuss different nanomaterial-based approaches that can inhibit HSP production via ATP regulation and their uses in PTT/PDT and cancer combination therapy such as CT and ST.

Therapeutic effect and metabolic fingerprinting of triple-negative breast cancer cells following exposure to a novel pH-responsive, gambogic acid-loaded micelle

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with a poor prognosis and lacks effective therapeutic targets. The use of gambogic acid (GA), a class of active ingredients in traditional Chinese medicine with anti-tumour potential, is limited in tumour therapy owing to its drawbacks and unclear organ toxicity. In this study, we used the pH-responsive amphiphilic block copolymer, PEOz-PCL, to create nanodrugs for GA delivery to MDA-MB-231 cells. The pH-responsive GA-loaded micelles were prepared through nanoprecipitation with a more homogeneous size. The average particle size was 42.29 ± 1.74 nm, and the zeta potential value was 9.88 ± 0.17 mV. The encapsulation rate was 85.06%, and the drug loading rate was 10.63%. The process was reproducible, and sustained release reached 80% in 96 h at acid pH 5.0. Furthermore, cellular tests using CCK-8, TUNEL, and flow cytometry revealed that pH-responsive GA-loaded micelles killed MDA-MB-231 cells more effectively and had much higher activity and targeting compared with free drugs. Metabolomic analysis of the changes in differential metabolites revealed that pH-responsive GA-loaded micelles may inhibit TNBC cells by causing amino acid anabolism, nucleotide metabolism, and glucose metabolism, as well as by affecting their energy sources. The study outcomes will help understand the mechanism of action and the therapeutic efficacy of pH-responsive GA-loaded micellesin vivo.

Ferroptosis: Emerging Role in Diseases and Potential Implication of Bioactive Compounds

Ferroptosis is a form of cell death that is distinguished from other types of death for its peculiar characteristics of death regulated by iron accumulation, increase in ROS, and lipid peroxidation. In the past few years, experimental evidence has correlated ferroptosis with various pathological processes including neurodegenerative and cardiovascular diseases. Ferroptosis also is involved in several types of cancer because it has been shown to induce tumor cell death. In particular, the pharmacological induction of ferroptosis, contributing to the inhibition of the proliferative process, provides new ideas for the pharmacological treatment of cancer. Emerging evidence suggests that certain mechanisms including the Xc- system, GPx4, and iron chelators play a key role in the regulation of ferroptosis and can be used to block the progression of many diseases. This review summarizes current knowledge on the mechanism of ferroptosis and the latest advances in its multiple regulatory pathways, underlining ferroptosis' involvement in the diseases. Finally, we focused on several types of ferroptosis inducers and inhibitors, evaluating their impact on the cell death principal targets to provide new perspectives in the treatment of the diseases and a potential pharmacological development of new clinical therapies.

MiR-1275 Targeting SPARC Promotes Gambogic Acid-Induced Inhibition of Gastric Cancer

Gambogic acid (GA) has been observed to effectively impede the progression of numerous types of cancers. In this study, we investigated the effects of miR-1275 and Secreted Protein Acidic and Cysteine Rich (SPARC) on GA in gastric cancer (GC). miR-1275 and SPARC expression were determined in GC cell lines and tissues using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The correlation between miR-1275 and SPARC expression was ascertained using Pearson's correlation coefficient. Cell proliferation was assessed using the cell counting kit-8 (CCK-8) assay. The Transwell assay was conducted to examine cell migration. A dual-luciferase reporter assay was used to verify the regulatory relationship between miR-1275 and SPARC. The levels of SPARC, Bcl-2, and Bax proteins were estimated using western blotting. To verify the effects of GA on the growth of GC cells in vivo, a tumorigenesis experiment was performed in nude mice. GA suppressed GC cell viability and migration, facilitated apoptosis, and inhibited tumor growth in vivo and in vitro. Low levels of miR-1275 been observed in GC cell lines and tissues. GA-treated GC cells manifested high miR-1275 levels. In functional experiments, miR-1275 enhanced the influence of GA on cell apoptosis, migration, and proliferation. Furthermore, GA treatment suppressed SPARC upregulation in GC cell lines and tissues. Pearson's correlation coefficient revealed that miR-1275 expression negatively correlated with SPARC expression. Mechanistically, miR-1275 promoted growth inhibition in GA-treated GC cells by targeting SPARC. Our study indicates that miR-1275 enhances the suppressive effect of GA on GC progression by inhibiting SPARC expression. Through this study, we contribute to the knowledge of a new mechanism by which GA suppresses GC progression.

Self-engineered binary nanoassembly enabling closed-loop glutathione depletion-amplified tumor ferroptosis

Ferroptosis has emerged as a promising target for anticancer treatment, comprising iron-dependent lipid peroxidation and excessive accumulation of reactive oxygen species. Given that glutathione (GSH) overproduced in tumor cells antagonizes the cellular oxidation system, the reduction of GSH production has been extensively explored to induce ferroptosis. However, reducing GSH production alone is insufficient to trigger an intense lipid peroxidation storm. It is highly desirable to achieve systemic GSH depletion through simultaneous production and consumption intervention. Herein, we propose a bidirectional blockage strategy for closed-loop GSH depletion-amplified tumor ferroptosis. Sorafenib (Sor) and gambogic acid (GA) were elaborately fabricated as a self-engineered carrier-free nanoassembly without any nanocarrier materials. The PEGylated dual-drug nanoassembly enables favorable co-delivery and tumor-specific release of Sor and GA. Notably, a closed-loop GSH depletion is observed as a result of a Sor-induced decrease in GSH production and GA-accelerated GSH consumption in vitro and in vivo. As expected, this uniquely engineered dual-drug nanoassembly demonstrates vigorous antitumor activity in 4T1 breast tumor-bearing mice. This study presents a novel nanotherapeutic modality for ferroptosis-driven cancer treatment.

Bioactive phytocompounds for oral cancer prevention and treatment: A comprehensive and critical evaluation

The high incidence of oral cancer combined with excessive treatment cost underscores the need for novel oral cancer preventive and therapeutic options. The value of natural agents, including plant secondary metabolites (phytochemicals), in preventing carcinogenesis and representing expansive source of anticancer drugs have been established. While fragmentary research data are available on antioral cancer effects of phytochemicals, a comprehensive and critical evaluation of the potential of these agents for the prevention and intervention of human oral malignancies has not been conducted according to our knowledge. This study presents a complete and critical analysis of current preclinical and clinical results on the prevention and treatment of oral cancer using phytochemicals. Our in-depth analysis highlights anticancer effects of various phytochemicals, such as phenolics, terpenoids, alkaloids, and sulfur-containing compounds, against numerous oral cancer cells and/or in vivo oral cancer models by antiproliferative, proapoptotic, cell cycle-regulatory, antiinvasive, antiangiogenic, and antimetastatic effects. Bioactive phytochemicals exert their antineoplastic effects by modulating various signaling pathways, specifically involving the epidermal growth factor receptor, cytokine receptors, toll-like receptors, and tumor necrosis factor receptor and consequently alter the expression of downstream genes and proteins. Interestingly, phytochemicals demonstrate encouraging effects in clinical trials, such as reduction of oral lesion size, cell growth, pain score, and development of new lesions. While most phytochemicals displayed minimal toxicity, concerns with bioavailability may limit their clinical application. Future directions for research include more in-depth mechanistic in vivo studies, administration of phytochemicals using novel formulations, investigation of phytocompounds as adjuvants to conventional treatment, and randomized clinical trials.

Bornyl acetate extracted from Sharen () inhibits proliferation, invasion and induces apoptosis by suppressing phosphatidylinositol-3-kinase/protein kinase B signaling in colorectal cancer

OBJECTIVE

To investigate the antitumor effects of bornyl acetate (BA) isolated from Sharen (Fructus Amomi) in colorectal cancer (CRC) and the underlying mechanisms.

METHODS

SW480 and HT29 cells were treated with increasing doses of BA in order to determine its antitumor effects in vitro. Cell viability, colony formation, cell cycle, and apoptosis as well as migration and invasion were assessed using various assays. In addition, the in vivo antitumor effects of BA were assessed using a xenograft mouse model. We then assessed the mechanism of action of BA by conducting pathway activator-mediated rescue experiments and assessed the protein levels by Western blot analysis.

RESULTS

BA showed anti-CRC tumor activities in vitro by suppressing cell proliferation and colony formation, inducing apoptosis, blocking cell cycle, and inhibiting migration and invasion. These effects were mediated via suppression of the phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) pathway. In the tumor xenograft experiment, BA was found to repress tumor growth in vivo with low toxicity.

CONCLUSIONS

The results demonstrated that BA exerts antitumor effects by suppressing the PI3K/AKT pathway, with low toxicity. Thus, BA might be a potential novel therapeutic agent for CRC.

Phytochemicals for the prevention and treatment of pancreatic cancer: Current progress and future prospects

Pancreatic cancer is the third leading cause of cancer-related deaths in the United States, owing to its aggressive nature and suboptimal treatment options, emphasizing the need for novel therapeutic approaches. Emerging studies have exhibited promising results regarding the therapeutic utility of plant-derived compounds (phytochemicals) in pancreatic cancer. The purpose of this review is to evaluate the potential of phytochemicals in the treatment and prevention of pancreatic cancer. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses was applied to collect articles for this review. Scholarly databases, including PubMed, Scopus and ScienceDirect, were queried for relevant studies using the following keywords: phytochemicals, phenolics, terpenoids, alkaloids, sulfur-containing compounds, in vitro, in vivo, clinical studies, pancreatic cancer, tumour, treatment and prevention. Aggregate results pooled from qualified studies indicate phytochemicals can inhibit pancreatic cancer cell growth or decrease tumour size and volume in animal models. These effects have been attributed to various mechanisms, such as increasing proapoptotic factors, decreasing antiapoptotic factors, or inducing cell death and cell cycle arrest. Notable signalling pathways modulated by phytochemicals include the rat sarcoma/mitogen activated protein kinase, wingless-related integration site/β-catenin and phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signal transduction pathways. Clinically, phytochemicals have been found to increase survival while being well-tolerated and safe, though research is scarce. While these promising results have produced great interest in this field, further in-depth studies are required to characterize the anticancer activities of phytochemicals before they can be utilized to prevent or treat pancreatic cancer in clinical practice.

Carrier-Free Gambogic Acid Dimer Self-Assembly Nanomedicines for Rheumatoid Arthritis Treatment

Introduction

The insufficient targeting delivery of therapeutic agents greatly impeded the treatment outcomes of rheumatoid arthritis (RA). Despite the recognized therapeutic advantages of gambogic acid (GBA) in inflammatory diseases, its high delivery efficiency to inflammatory site still limits its clinical application. Self-assembly of drug dimers into carrier-free nanoparticles (NPs) has become a straightforward and attractive approach to develop nanomedicines for RA treatment. Herein, homodimers of GBA were designed to form the carrier-free NPs by self-assembly for RA treatment.

Methods

The synthetic gambogic acid dimers (GBA2) were self-assembled into NPs using a one-step solvent evaporation method. The size distribution, morphology, drug-loading efficiency (DLE) and storage stability were evaluated. A molecular dynamic simulation was conducted to gain further insight into the self-assembly mechanisms of GBA2/NPs. Besides, we investigated the cytotoxicity, apoptosis and cellular uptake profiles of GBA2/NPs in macrophages and osteoclasts. Finally, the specific biodistribution on the ankles of adjuvant-induced arthritis (AIA) mice, and the anti-RA efficacy of the AIA rat model were assessed.

Results

GBA2/NPs exhibited the uniform spherical structure, possessing excellent colloidal stability, high self-assembly stability, high drug loading and low hemolytic activity. Comparing with GBA, GBA2/NPs showed higher cytotoxicity, cellular uptake and apoptosis rate against osteoclasts. In addition, GBA2/NPs exhibited much higher accumulation in ankle joints in vivo. As expected, the systematic administration of GBA2/NPs resulted in the greater alleviation of arthritic symptoms, cartilage protection, and inflammation, notably the reduced systemic toxicity compared to free GBA.

Conclusion

GBA2/NPs formed GBA dimers exhibited the superior accumulation in the inflamed joint and anti-RA activity, potentially attributing to the similar extravasation through leaky vasculature and subsequent inflammatory cell-mediated sequestration ("ELVIS") effects in inflamed joint and the enhanced cellular uptake in macrophages and osteoclasts. Our findings provide substantial evidence that self-assembly of GBA2/NPs would be a promising therapeutic alternative for RA treatment.

Mechanism of anticancer effect of gambogic acid on gastric signet ring cell carcinoma

Gambogic acid has demonstrated inhibitory effects on the growth of various cancer cell types, such as breast cancer, pancreatic cancer, prostate cancer, lung cancer, and osteosarcoma. This study aims to investigate the antiproliferative activity of Gambogic acid on SNU-16 cells derived from gastric signet ring cell carcinoma and elucidate the underlying mechanisms. The cytotoxic effect of gambogic acid was evaluated in SNU-16 cells by treating them with different concentrations of the compound, and the XTT cell viability assay was employed to assess cell viability. ELISA was used to measure bax, BCL-2, caspase 3, PARP, and 8-oxo-dG levels. Additionally, immunofluorescence staining was applied to assess 8-oxo-dG and LC3β levels in SNU-16 cells. It was observed that gambogic acid exerted a dose-dependent and statistically significant antiproliferative effect on SNU-16 cells. The IC50 value of gambogic acid in SNU-16 cells was found to be 655.1 nM for 24 h. Subsequent investigations conducted using the IC50 dose revealed a significant upregulation of apoptotic proteins including cleaved caspase 3, Bax, and cleaved PARP (p < 0.001), along with a downregulation of BCL-2 (p < 0.001), an anti-apoptotic protein. Moreover, the administration of this drug led to an upregulation of 8-oxo-dG (p < 0.001), a widely acknowledged biomarker indicating oxidative damage in DNA, as well as an increase in LC3β levels (p < 0.05), a marker associated with autophagy. The antiproliferative effect of gambogic acid against gastric signet ring cell carcinoma is attributed to its ability to induce apoptosis and autophagy. This discovery highlights the promising potential of gambogic acid as a treatment option for gastric signet ring cell carcinoma.

Gambogic Acid Inhibits Gastric Cancer Cell Proliferation through Necroptosis

Gambogic acid (GA) is a natural xanthonoid secreted by Garcinia hanburyi tree. It possesses anti-cancer activity in various types of cancers. In gastric cancer, it inhibits cell proliferation through increasing apoptosis. However, whether necroptosis is involved in the GA-induced proliferation inhibited in gastric cancer is unknown. In the present study, we found that RIPK1 specific inhibitor necrostatin-1 (Nec-1) attenuated GA-induced proliferation inhibition. GA treatment increased the phosphorylation of necroptosis-related proteins, RIPK1, RIPK3, and MLKL, and their interactions to form the necrosome complex. The effector protein Drp-1 was dephosphorylated by GA treatment. Inhibition of necroptosis by different inhibitors and PGAM5 knockdown attenuated GA-induced cell death in gastric cancer cell lines, thereby attenuating GA-caused cell proliferation inhibition. All the data supported the conclusion that GA could inhibit gastric cancer cell proliferation by inducing necroptosis.

Lactoferrin-Modified Gambogic Acid Liposomes for Colorectal Cancer Treatment

Colorectal cancer (CRC) therapy is a big challenge, and seeking an effective and safe drug is a pressing clinical need. Gambogic acid is a potent antineoplastic agent without the drawback of bone marrow suppression. To improve its druggability (e.g., poor water solubility and tumor delivery), a lactoferrin-modified gambogic acid liposomal delivery system (LF-lipo) was developed to enhance the treatment efficacy of CRC. The LF-lipo can specifically bind LRP-1 expressed on colorectal cancer cells to enhance drug delivery to the tumor cells and yield enhanced therapeutic efficacy. The LF-lipo promoted tumor cell apoptosis and autophagy, reduced reactive oxygen species (ROS) levels in tumor cells, and inhibited angiogenesis; moreover, it could also repolarize tumor-associated macrophages from the M2 to M1 phenotype and induce ICD to activate T cells, exhibiting the capability of remodeling the tumor immune microenvironment. The liposomal formulation yielded an efficient and safe treatment outcome and has potential for clinical translation.

Mitochondria-Anchoring Self-assembled Nanoparticles for Multi-Path Energy Depletion: A "Nano Bomb" in Chemo-co-Starvation Therapy

As the main systemic treatment for triple-negative breast cancer (TNBC), the bleak medical prognosis of chemotherapy resulted in impaired life quality by tumor recurrence and metastasis. The feasible cancer starvation therapy could inhibit tumor progression by blocking energy supplements, however, the mono-therapeutic modality showed limited curing efficacy due to heterogeneity and abnormal energy metabolism of TNBC. Thus, the development of a synergistic nano-therapeutic modality involving different anti-tumor mechanisms to simultaneously transport medicines to the organelle where metabolism took place, might remarkably improve curing efficacy, targeting ability, and bio-safety. Herein, the hybrid BLG@TPGS NPs were prepared by doping multi-path energy inhibitors Berberine (BBR) and Lonidamine (LND) as well as the chemotherapeutic agent Gambogic acid (GA). Our research indicated that Nanobomb\mathord{-} BLG@TPGS NPs inherited the mitochondria targeting ability from BBR to accumulate precisely at the "energy factory" mitochondria, and then induce starvation therapy to efficiently eradicated cancer cells by coordinately powered off tumor cells via a "three-prone strategy" to cut off mitochondrial respiration, glycolysis, and glutamine metabolism. The inhibition of tumor proliferation and migration was enlarged by the synergistic combination with chemotherapy. Besides, apoptosis via mitochondria pathway and mitochondria fragmentation supported the hypothesis that NPs eliminated MDA-MB-231 cells by violently attacking MDA-MB-231 cells and especially the mitochondria. In summary, this synergistic chemo-co-starvation nanomedicine proposed an innovative site-specific targeting strategy for improved tumor treatment and decreased toxicity to normal tissues, which provided an option for clinical TNBC-sensitive treatment.

Anti-proliferation and induction of mitochondria-mediated apoptosis by Garcinia hanburyi resin in colorectal cancer cells

Introduction

Several parts of Garcinia hanburyi are used in traditional medicine for many purposes. In this study, Garcinia hanburyi resin (GHR) was explored for possible anti-proliferative effects and the underlying mechanism on colorectal cancer (CRC) cells.

Methods

Gambogic acid (GA) content in GHR was analyzed by HPLC method. The cytotoxicities of GA and GHR were assessed in human CRC cell lines (SW480 and Caco-2) and normal colon cells (CCD841 CoN) using a trypan blue exclusion assay, MTS assay, and cell morphology analysis. Cell cycle and apoptosis at its half maximal inhibitory concentration (IC50) were analyzed using flow cytometry. And, the levels of intrinsic apoptosis-related proteins were measured by Western blot analysis.

Results

GA was the major compound as 71.26% of the GHR. The cell viability of CRC cells was decreased in a time- and dose-dependent manner after exposure to GHR. The selectivity index indicated that GHR had a high degree of selectivity against CRC cells. The same result was obtained for GA treatment. In addition, GHR markedly induced typical apoptotic morphology of CRC cells, but had no obvious effect on normal colon cells. GHR induced apoptosis with the cell cycle arrest at the G2/M phase. An increase in Bax/Bcl-2 ratio and a decrease in procaspase-3 proteins indicated that GHR promoted apoptosis by disrupting the mitochondrial outer membrane permeability and the subsequent activation of caspase-3.

Conclusion

GHR, which contained GA as an active compound, significantly inhibited CRC cell proliferation via the induction of intrinsic apoptosis, while having low toxicity on normal colon cells. Therefore, GHR could be proposed as a potent candidate for the treatment of CRC.

The pyroptotic role of Caspase-3/GSDME signalling pathway among various cancer: A Review

Cytotoxic drugs have long been recognised to kill cancer cells through apoptosis. According to a current study, pyroptosis inhibits cell proliferation and shrinks tumors. Pyroptosis and apoptosis are caspase-dependent programmed cell death (PCD) processes. Inflammasomes activate caspase-1 and latent cytokines, including IL-1β and IL-18, to cleave gasdermin E (GSDME) and induce pyroptosis. Gasdermin proteins activate caspase-3 to induce pyroptosis, which is associated with tumour genesis, development, and therapy response. These proteins may serve as therapeutic biomarkers for cancer detection, and their antagonists may be a new target. Caspase-3, a crucial protein in both pyroptosis and apoptosis, governs tumour cytotoxicity when activated, and GSDME expression modulates this. Once active caspase-3 cleaves GSDME, its N-terminal domain punches holes in the cell membrane, causing it to expand, burst, and die. To understand the cellular and molecular mechanisms of PCD mediated by caspase-3 and GSDME, we focused on pyroptosis. Hence, caspase-3 and GSDME may be promising targets for cancer treatment.

Optimization of amino acid-based poly(ester urea urethane) nanoparticles for the systemic delivery of gambogic acid for treating triple negative breast cancer

Amino acid-based poly(ester urea urethane) (AA-PEUU) is developed from amino acid-based ester urea building blocks interconnected with urethane blocks functionalized with poly(ethylene glycol) (PEG). Each functional block consists of structural design features that could impact the properties and performances of AA-PEUU as a nanocarrier for the systemic delivery of gambogic acid (GA). The multifunctional AA-PEUU structure provides broad tunability to enable the optimization of nanocarriers. The study investigates the structure-property relationship by fine-tuning the structure of AA-PEUU, including the amino acid type, hydrocarbons, the ratio of functional building blocks, and PEGylation, to identify the nanoparticle candidate with optimized delivery performances. Compared to free GA, the optimized PEUU nanocarrier improves the intratumoral distribution of GA by more than 9-fold, which significantly enhances the bioavailability and persistence of GA after intravenous administration. In an MDA-MB-231 xenograft mouse model, GA delivered by the optimized AA-PEUU nanocarrier exhibits significant tumor inhibition, apoptosis induction, and the anti-angiogenesis effect. The study demonstrates the potency of engineering AA-PEUU nanocarriers with tailor-designed structures and versatile tunability for the systemic delivery of therapeutics in the treatment of triple negative breast tumor.

Synergistic effect of docetaxel and gambogic acid on bone metastasis of lung cancer

INTRODUCTION

Gambogic acid (GA) as an active compound isolated from Gamboge, have been investigated for many years and proved to be a promising natural anticancer agent for clinical treatment. This study aimed to investigate the inhibitory effect of docetaxel (DTX) combined with gambogic acid on bone metastasis of lung cancer.

METHODS

The anti-proliferation effect of the combination of DTX and GA on Lewis lung cancer (LLC) cells was determined by MTT assays. The anticancer effect of the combination of DTX and GA on bone metastasis of lung cancer in vivo was explored. Evaluation of the efficacy of drug therapy was performed by comparing the degree of bone destruction and the pathological section of bone tissue of the treated mice with that of the control mice.

RESULTS

In vitro cytotoxicity, cell migration, and osteoclast-induced formation assay showed that GA enhanced the therapeutic effect of DTX in Lewis lung cancer cell with a synergistic effect. In an orthotopic mouse model of bone metastasis, the average survival of the DTX+GA combination group (32.61d±1.06 d) was significantly increased compared with that of the DTX group (25.75 d±0.67 d) or GA group (23.99 d±0.58 d), *P<0.01.

CONCLUSION

The combination of DTX and GA has synergistic effect and resulted in more effective inhibition of tumor metastasis, providing a strong preclinical rationale for the clinical development of the DTX+GA combination for treating bone metastasis of lung cancer.

Z-Trisubstituted α,β-Unsaturated Esters and Acid Fluorides through Stereocontrolled Catalytic Cross-Metathesis

Catalytic cross-metathesis (CM) reactions that can generate trisubstituted alkenes in high stereoisomeric purity are important but remain limited in scope. Here, CM reactions are introduced that generate Z-trisubstituted α-methyl, α,β-unsaturated, alkyl and aryl esters, thiol esters, and acid fluorides. Transformations are promoted by a Mo bis-aryloxide, a monoaryloxide pyrrolide, or a monoaryloxide chloride complex; air-stable and commercially available paraffin tablets containing a Mo complex may also be used. Alkyl, aryl, and silyl carboxylic esters as well as thiol esters and acid fluoride reagents are either purchasable or can be prepared in one step. Products were obtained in 55-95% yield and in 88:12->98:2 Z/E ratio (typically >95:5). The applicability of the approach is highlighted by a two-step conversion of citronellol to an isomintlactone precursor (1.7 g, 73% yield, and 97:3 Z/E) and a single-step transformation of lanosterol acetate to 3-epi-anwuweizic acid (72% yield and 94:6 Z/E). Included are the outcomes of DFT studies, regarding several initially puzzling catalyst activity trends, providing the following information: (1) it is key that a disubstituted Mo alkylidene, generated by a competing homo-metathesis (HM) pathway, can re-enter the productive CM cycle. (2) Whereas in a CM cycle the formation of a molybdacyclobutane is likely turnover-limiting, the collapse of related metallacycles in a HM cycle is probably rate-determining. It is therefore the relative energy barrier required for these steps that determines whether CM or HM is dominant with a particular complex.

Plant-derived compounds for treating autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD), the most common monogenic hereditary kidney disease, is the fourth leading cause of end-stage kidney disease worldwide. In recent years, significant progress has been made in delaying ADPKD progression with different kinds of chemical drugs, such as tolvaptan, rapamycin, and somatostatin. Meanwhile, numerous plant-derived compounds have been investigated for their beneficial effects on slowing ADPKD progression. Among them, saikosaponin-d, Ganoderma triterpenes, curcumin, ginkgolide B, steviol, resveratrol, Sparganum stoloniferum Buch.-Ham, Cordyceps sinensis, triptolide, quercitrin, naringin, cardamonin, gambogic acid, and olive leaf extract have been found to retard renal cyst development by inhibiting cell proliferation or promoting cell apoptosis in renal cyst-lining epithelial cells. Metformin, a synthesized compound derived from French lilac or goat's rue (Galega officinalis), has been proven to retard the progression of ADPKD. This review focuses on the roles and mechanisms of plant-derived compounds in treating ADPKD, which may constitute promising new therapeutics in the future.

Determination and tissue distribution comparisons of five xanthones after orally administering crude and processed gamboge

Caged polyprenylated xanthones are the main active ingredients isolated from the resin of Garcinia hanburyi, which has been reported to exhibit potential anticancer and anti-inflammatory activities. This study aimed to develop sensitive and specific ultra-performance liquid chromatography coupled with the triple quadrupole mass spectrometry method for investigating the tissue distribution of five xanthones in rats: β-morellic acid, isogambogenic acid, gambogenic acid, R-gambogic acid and S-gambogic acid. All tissue samples were prepared using the liquid-liquid extraction method and separated on a C₈ column with a gradient system. Detection was performed on a triple quadrupole mass spectrometer in multiple-reaction monitoring using positive ionization. The method established in this assay was successfully applied to the tissue distribution study of the five selected xanthones after orally administering crude and processed gamboge in rat tissues. The results indicated that these five xanthones were distributed to rat tissues rapidly and could be detected in all of the selected tissues after oral administration. After processing, the contents of R-gambogic acid and S-gambogic acid in the gastrointestinal tract were significantly reduced. The findings of this study might be helpful in further understanding the processing mechanism of gamboge and providing references for its reasonable clinical application.

Prodrug Nanosensitizer Overcomes the Radiation Resistance of Hypoxic Tumor

Clinical radiation therapy (RT) is often hindered by the low radiation energy absorption coefficient and the hypoxic features of tumor tissues. Among the tremendous efforts devoted to overcoming the barriers to efficient RT, the application of hypoxic radiosensitizers and cell-cycle-specific chemotherapeutics has shown great potential. However, their effectiveness is often compromised by their limited bioavailability, especially in the hypoxic region, which plays a major role in radioresistance. Herein, to simultaneously improve the delivery efficacy of both hypoxic radiosensitizer and cell-cycle-specific drug, a gambogic acid (GA) metronidazole (MN) prodrug (GM) was designed and synthesized based on GA, a naturally occurring chemotherapeutic and multiple pathway inhibitor, and MN, a typical hypoxic radiosensitizer. In combination with MN-containing block copolymers, the prodrug nanosensitizer (NS) of GM was obtained. Owing to the bioreduction of MN, the as-designed prodrug could be efficiently delivered to hypoxic cells and act on mitochondria to cause the accumulation of reactive oxygen species. The strong G₂/M phase arrest caused by the prodrug NS could further sensitize treated cells to external radiation under hypoxic conditions by increasing DNA damage and delaying DNA repair. After coadministration of the NS with a well-established tissue-penetrating peptide, efficient tumor accumulation, deep tumor penetration, and highly potent chemoradiotherapy could be achieved.

Load and release of gambogic acid via dual-target ellipsoidal-Fe3O4@SiO2@mSiO2-C18@dopamine hydrochloride -graphene quantum dots-folic acid and its inhibition to VX2 tumor cells

Ellipsoidal-Fe₃O₄@SiO₂@mSiO₂-C₁₈@dopamine hydrochloride-graphene quantum dots-folic acid (ellipsoidal-HMNPs@PDA-GQDs-FA), a dual-functional drug carrier, was stepwise constructed. Theα-Fe₂O₃ellipsoidal nanoparticles were prepared by a hydrothermal method, and then coated with SiO₂by Stöber method. The resulting core-shell structure, Fe₃O₄@SiO₂@mSiO₂-C₁₈magnetic nano hollow spheres, abbreviated as HMNPs, was finally grafted with graphene quantum dots (GQDs), dopamine hydrochloride (PDA) and folic acid (FA) by amide reaction to obtain HMNPs@PDA-GQDs-FA. Transmission electron microscopy, Fourier transform infrared spectroscopy, fluorescence spectroscopy and element analysis proved the successful construction of the HMNPs@PDA-GQDs-FA nanoscale carrier-cargo composite. The carrier HMNPs@PDA-GQDs-FA has higher load (51.63 ± 1.53%) and release (38.56 ± 1.95%) capacity for gambogic acid (GA). Cytotoxicity test showed that the cell survival rate was above 95%, suggesting the cytotoxicity of the carrier-cargo was very low. The cell lethality (74.91 ± 1.2%) is greatly improved after loading GA because of the magnetic targeting of HMNPs, the targeting performance of FA to tumor cells, and the pH response to the surrounding environment of tumor cells of PDA. All results showed that HMNPs@PDA-GQDs-FA had good biocompatibility and could be used in the treatment of VX2 tumor cells after loading GA.

Investigations into the antibacterial effects and potential mechanism of gambogic acid and neogambogic acid

The growing threat of antibiotic-resistant bacterial infections to public health necessitates the development of novel antibacterial agents. Inhibiting bacterial cell wall synthesis has remained a key focus for antibiotic development. Our search for inhibitors of undecaprenyl diphosphate synthase (UPPS), an essential enzyme required for bacterial cell wall formation, revealed that two primary components of gamboge, gambogic acid (GA) and neogambogic acid (NGA), significantly inhibited the activity of Enterococcus faecalis UPPS (EfaUPPS) with the half maximal inhibitory concentrations (IC₅₀) of 3.08 μM and 3.07 μM, respectively. In the in vitro antibacterial assay, both GA and NGA also exhibited inhibitory activities against E. faecalis with the minimal inhibitory concentrations (MICs) of 2 μg/mL. Using microscale thermophoresis, molecular docking, and enzymatic assays, we further confirmed that GA and NGA occupy the substrate binding pocket of EfaUPPS with micro-molar binding affinity, preventing the natural substrates farnesyl diphosphate (FPP) from entering. Mutagenesis analysis revealed that L91 and L146 are two key residues in the binding between GA/NGA and UPPS. Furthermore, we also demonstrated that GA and NGA can improve E. faecalis-induced undesirable inflammation in a mouse infection model. Taken together, our findings provide a basis for structural optimization of GA/NGA to develop improved antibiotic leads and enhance treatment success rates in clinical practice.

Nanoemulsion Co-Loaded with XIAP siRNA and Gambogic Acid for Inhalation Therapy of Lung Cancer

Lung cancer is a leading cause of cancer mortality worldwide, with a 5-year survival rate of less than 20%. Gambogic acid (GA) is a naturally occurring and potent anticancer agent that destroys tumor cells through multiple mechanisms. According to the literature, one of the most potent inhibitors of caspases and apoptosis currently known is the X-linked Inhibitor of Apoptosis Protein (XIAP). It is highly expressed in various malignancies but has little or no expression in normal cells, making it an attractive target for cancer treatment. Here we report the development of a chitosan (CS)-based cationic nanoemulsion-based pulmonary delivery (p.d.) system for the co-delivery of antineoplastic drugs (GA) and anti-XIAP small interfering RNA (siRNA). The results showed that the chitosan-modified cationic nanoemulsions could effectively encapsulate gambogic acid as well as protect siRNA against degradation. The apoptosis analysis confirmed that the cationic nanoemulsions could induce more apoptosis in the A549 cell line. In addition, most drugs and siRNAs have a long residence time in the lungs through pulmonary delivery and show greater therapeutic effects compared to systemic administration. In summary, this work demonstrates the applicability of cationic nanoemulsions for combined cancer therapy and as a promising approach for the treatment of lung cancer.

Gambogic Acid Induces Pyroptosis of Colorectal Cancer Cells through the GSDME-Dependent Pathway and Elicits an Antitumor Immune Response

Pyroptosis is a recently identified form of programmed cell death (PCD) that exerts a vital influence on the antitumor immune response. GA, a xanthone structure isolated from gamboge resin, is a naturally occurring bioactive ingredient with several anticancer activities, such as activities that affect cell cycle arrest, apoptosis, and autophagy. Here, we found that GA decreased the viability of the CRC cell lines, HCT116 and CT26, in a dose- and time-dependent manner, and multiple pores and large bubbles in the membranes, which are morphological characteristics of pyroptosis, were observed by light microscopy and transmission electron microscopy (TEM). Furthermore, the cleavage of gasdermin E (GSDME) was observed after exposure to GA, along with concomitant activation of caspase-3. Additionally, GSDME-dependent pyroptosis triggered by GA could be attenuated by siRNA-mediated knockdown of GSDME and treatment with the caspase-3 inhibitor. Moreover, we found that GA induced pyroptosis and significantly inhibited tumor growth in CT26 tumor-bearing mice. Strikingly, significantly increased proportions of CD3⁺ T cells, cytotoxic T lymphocytes (CTLs), and dendritic cells (DCs) were observed in the tumor microenvironment in the GA-treated groups. Moreover, significantly increased proportions of CTLs and effector memory T cells (TEM) (CD8⁺ CD44⁺ CD62L^-) were also detected in the spleens of the GA-treated groups, suggesting that the pyroptosis-induced immune response generated a robust memory response that mediated protective immunity. In this study, we revealed a previously unrecognized mechanism by which GA induces GSDME-dependent pyroptosis and enhances the anticancer immune response. Based on this mechanism, GA is a promising antitumor drug for CRC treatment that induces caspase-3-GSDME-dependent pyroptosis. This study provides novel insight into cancer chemoimmunotherapy.

Screening of traditional Chinese medicine monomers as ribonucleotide reductase M2 inhibitors for tumor treatment

BACKGROUND

Ribonucleotide reductase (RR) is a key enzyme in tumor proliferation, especially its subunit-RRM2. Although there are multiple therapeutics for tumors, they all have certain limitations. Given their advantages, traditional Chinese medicine (TCM) monomers have become an important source of anti-tumor drugs. Therefore, screening and analysis of TCM monomers with RRM2 inhibition can provide a reference for further anti-tumor drug development.

AIM

To screen and analyze potential anti-tumor TCM monomers with a good binding capacity to RRM2.

METHODS

The Gene Expression Profiling Interactive Analysis database was used to analyze the level of RRM2 gene expression in normal and tumor tissues as well as RRM2's effect on the overall survival rate of tumor patients. TCM monomers that potentially act on RRM2 were screened via literature mining. Using AutoDock software, the screened monomers were docked with the RRM2 protein.

RESULTS

The expression of RRM2 mRNA in multiple tumor tissues was significantly higher than that in normal tissues, and it was negatively correlated with the overall survival rate of patients with the majority of tumor types. Through literature mining, we discovered that berberine, ursolic acid, gambogic acid, cinobufagin, quercetin, daphnetin, and osalmide have inhibitory effects on RRM2. The results of molecular docking identified that the above TCM monomers have a strong binding capacity with RRM2 protein, which mainly interacted through hydrogen bonds and hydrophobic force. The main binding sites were Arg330, Tyr323, Ser263, and Met350.

CONCLUSION

RRM2 is an important tumor therapeutic target. The TCM monomers screened have a good binding capacity with the RRM2 protein.

Polyphenols: Chemoprevention and therapeutic potentials in hematological malignancies

Polyphenols are one of the largest plant-derived natural product and they play an important role in plants' defense as well as in human health and disease. A number of them are pleiotropic molecules and have been shown to regulate signaling pathways, immune response and cell growth and proliferation which all play a role in cancer development. Hematological malignancies on the other hand, are cancers of the blood. While current therapies are efficacious, they are usually expensive and with unwanted side effects. Thus, the search for newer less toxic agents. Polyphenols have been reported to possess antineoplastic properties which include cell cycle arrest, and apoptosis via multiple mechanisms. They also have immunomodulatory activities where they enhance T cell activation and suppress regulatory T cells. They carry out these actions through such pathways as PI3K/Akt/mTOR and the kynurenine. They can also reverse cancer resistance to chemotherapy agents. In this review, i look at some of the molecular mechanism of action of polyphenols and their potential roles as therapeutic agents in hematological malignancies. Here i discuss their anti-proliferative and anti-neoplastic activities especially their abilities modulate signaling pathways as well as immune response in hematological malignancies. I also looked at clinical studies done mainly in the last 10-15 years on various polyphenol combination and how they enhance synergism. I recommend that further preclinical and clinical studies be carried out to ensure safety and efficacy before polyphenol therapies be officially moved to the clinics.

Redox-Responsive Drug Delivery Systems: A Chemical Perspective

With the widespread global impact of cancer on humans and the extensive side effects associated with current cancer treatments, a novel, effective, and safe treatment is needed. Redox-responsive drug delivery systems (DDSs) have emerged as a potential cancer treatment with minimal side effects and enhanced site-specific targeted delivery. This paper explores the physiological and biochemical nature of tumors that allow for redox-responsive drug delivery systems and reviews recent advances in the chemical composition and design of such systems. The five main redox-responsive chemical entities that are the focus of this paper are disulfide bonds, diselenide bonds, succinimide-thioether linkages, tetrasulfide bonds, and platin conjugates. Moreover, as disulfide bonds are the most commonly used entities, the review explored disulfide-containing liposomes, polymeric micelles, and nanogels. While various systems have been devised, further research is needed to advance redox-responsive drug delivery systems for cancer treatment clinical applications.

Phytochemicals for the Prevention and Treatment of Renal Cell Carcinoma: Preclinical and Clinical Evidence and Molecular Mechanisms

Simple Summary

Renal cell carcinoma (RCC) is the most frequently diagnosed kidney cancer. Once RCC metastasizes, successful treatment is difficult to achieve. There is an apparent need for novel approaches to prevent and treat RCC. Phytochemicals are naturally derived compounds gaining increasing scientific interest due to their cancer preventive and chemotherapeutic properties. These phytochemicals have been shown to exhibit a multitude of anticancer effects against RCC. In this systematic review, we critically evaluate the potential these natural compounds possess for the prevention and treatment of RCC and discuss the future implications this may have in the fight against kidney cancer.

Abstract

Renal cell carcinoma (RCC) is associated with about 90% of renal malignancies, and its incidence is increasing globally. Plant-derived compounds have gained significant attention in the scientific community for their preventative and therapeutic effects on cancer. To evaluate the anticancer potential of phytocompounds for RCC, we compiled a comprehensive and systematic review of the available literature. Our work was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. The literature search was performed using scholarly databases such as PubMed, Scopus, and ScienceDirect and keywords such as renal cell carcinoma, phytochemicals, cancer, tumor, proliferation, apoptosis, prevention, treatment, in vitro, in vivo, and clinical studies. Based on in vitro results, various phytochemicals, such as phenolics, terpenoids, alkaloids, and sulfur-containing compounds, suppressed cell viability, proliferation and growth, showed cytotoxic activity, inhibited invasion and migration, and enhanced the efficacy of chemotherapeutic drugs in RCC. In various animal tumor models, phytochemicals suppressed renal tumor growth, reduced tumor size, and hindered angiogenesis and metastasis. The relevant antineoplastic mechanisms involved upregulation of caspases, reduction in cyclin activity, induction of cell cycle arrest and apoptosis via modulation of a plethora of cell signaling pathways. Clinical studies demonstrated a reduced risk for the development of kidney cancer and enhancement of the efficacy of chemotherapeutic drugs. Both preclinical and clinical studies displayed significant promise of utilizing phytochemicals for the prevention and treatment of RCC. Further research, confirming the mechanisms and regulatory pathways, along with randomized controlled trials, are needed to establish the use of phytochemicals in clinical practice.

A Quantitative Metal-Encoded Conjugate Platform for Targeting Ligand Discovery

The indiscriminate biodistribution of therapeutics can be a key barrier to their safety and efficacy. Localization of compounds into non-diseased tissues often leads to both toxic and dose-limiting effects. To overcome this barrier, nanomedicine implements targeting agents to localize or selectively uptake drugs at disease sites. However, to date there are only a small number of targeting agents with limited scope for targeting tissues. Small-molecule ligands are particularly attractive as targeting agents due to their relatively low cost, tunability, and ease of conjugation. Currently, there are no systematic approaches to the discovery of new small-molecule targeting ligands. Here, we developed a quantitative metal-encoded conjugate platform to determine the biodistribution of multiple small molecules in vivo. By utilizing lanthanide metal complexes, this platform successfully distinguished known ligands with differential tissue targeting in vivo. This system will facilitate the discovery of small molecules as targeting ligands and can accelerate the identification of novel biological targets for tissue-targeted drug delivery.

Co-Targeting Tumor Angiogenesis and Immunosuppressive Tumor Microenvironment: A Perspective in Ethnopharmacology

Tumor angiogenesis is one of the most important processes of cancer deterioration via nurturing an immunosuppressive tumor environment (TME). Targeting tumor angiogenesis has been widely accepted as a cancer intervention approach, which is also synergistically associated with immune therapy. However, drug resistance is the biggest challenge of anti-angiogenesis therapy, which affects the outcomes of anti-angiogeneic agents, and even combined with immunotherapy. Here, emerging targets and representative candidate molecules from ethnopharmacology (including traditional Chinese medicine, TCM) have been focused, and they have been proved to regulate tumor angiogenesis. Further investigations on derivatives and delivery systems of these molecules will provide a comprehensive landscape in preclinical studies. More importantly, the molecule library of ethnopharmacology meets the viability for targeting angiogenesis and TME simultaneously, which is attributed to the pleiotropy of pro-angiogenic factors (such as VEGF) toward cancer cells, endothelial cells, and immune cells. We primarily shed light on the potentiality of ethnopharmacology against tumor angiogenesis, particularly TCM. More research studies concerning the crosstalk between angiogenesis and TME remodeling from the perspective of botanical medicine are awaited.

Potential Application of Gambogic Acid for Retarding Renal Cyst Progression in Polycystic Kidney Disease

Abnormal cell proliferation and accumulation of fluid-filled cysts along the nephrons in polycystic kidney disease (PKD) could lead to a decline in renal function and eventual end-stage renal disease (ESRD). Gambogic acid (GA), a xanthone compound extracted from the brownish resin of the Garcinia hanburyi tree, exhibits various pharmacological properties, including anti-inflammation, antioxidant, anti-proliferation, and anti-cancer activity. However, its effect on inhibiting cell proliferation in PKD is still unknown. This study aimed to determine the pharmacological effects and detailed mechanisms of GA in slowing an in vitro cyst growth model of PKD. The results showed that GA (0.25–2.5 μM) significantly retarded MDCK cyst growth and cyst formation in a dose-dependent manner, without cytotoxicity. Using the BrdU cell proliferation assay, it was found that GA (0.5–2.5 μM) suppressed MDCK and Pkd1 mutant cell proliferation. In addition, GA (0.5–2.5 μM) strongly inhibited phosphorylation of ERK1/2 and S6K expression and upregulated the activation of phosphorylation of AMPK, both in MDCK cells and Pkd1 mutant cells. Taken together, these findings suggested that GA could retard MDCK cyst enlargement, at least in part by inhibiting the cell proliferation pathway. GA could be a natural plant-based drug candidate for ADPKD intervention.

Ultrasound-triggered drug delivery for glioma therapy through gambogic acid-loaded nanobubble-microbubble complexes

Glioma is one of the most common primary brain tumors. Gambogic acid (GA) is widely used in tumor chemotherapy. However, GA has poor water solubility, low bioavailability, and difficult permeability across the blood-brain barrier (BBB), leading to poor efficacy against brain tumors. In our study, we developed negatively charged GA-loaded PLGA nanobubbles [GA/poly(lactic-co-glycolic acid) (PLGA)] and conjugated them onto the surface of cationic lipid microbubbles (CMBs) through electrostatic interactions. The resulting GA/PLGA-CMB complex was characterized for its particle size, distribution, drug encapsulation efficiency, and ultrasound imaging property, revealing a high drug encapsulation efficiency and excellent contrast imaging capability. Importantly, significantly enhanced GA delivery into the brain could be observed after the intravenous administration of GA/PLGA-CMBs combined with low-intensity focused ultrasound (FUS) due to the cavitation from CMBs, which mediated blood-brain barrier (BBB) opening. Taking advantage of the opened BBB, GA/PLGA nanobubbles could be delivered into the tumor. Then, the second FUS irradiation at higher energy was used to induce the cavitation of GA/PLGA nanobubbles, producing the second cavitation on tumor cells, significantly enhancing the ability of GA to enter tumor cells and inhibit tumor growth inhibition efficacy.

The Effect of α-Mangostin and Cisplatin on Ovarian Cancer Cells and the Microenvironment

Ovarian cancer is one of the cancers that, unfortunately, is detected at a late stage of development. The current use of treatment has many side effects. Notably, up to 20% of patients show cisplatin resistance. We assess the effects of cisplatin and/or α-mangostin, a natural plant derivative, on ovarian cancer cells and on the cancer cell microenvironment. The effect of cisplatin and/or α-mangostin on the following cells of ovarian cancer lines: A2780, TOV-21G, and SKOV-3 was verified using the XTT cytotoxicity assay. The separate and combined effects of tested drugs on ovarian cancer cell viability were assessed. We assessed the influence of chemotherapeutic agents on the possibility of modulating the microenvironment. For this purpose, we isolated exosomes from drug-treated and untreated ovarian cancer cells. We estimated the differences in the amounts of exosomes released from cancer cells (NTA technique). We also examined the effects of isolated exosome fractions on normal human cells (NHDF human fibroblast line). In the present study, we demonstrate that treatment of A2780, SKOV-3, and TOV-21G cells with α-mangostin in combination with cisplatin can allow a reduction in cisplatin concentration while maintaining the same cytotoxic effect. Ovarian cancer cells release a variable number of exosomes into the microenvironment when exposed to α-mangostin and/or cisplatin. However, it is important to note that the cargo carried by exosomes released from drug-treated cells may be significantly different.

Research Progress in the Field of Gambogic Acid and Its Derivatives as Antineoplastic Drugs

Gambogic acid (GA) is a natural product with a wide range of pharmacological properties. It plays an important role in inhibiting tumor growth. A large number of GA derivatives have been designed and prepared to improve its shortcomings, such as poor water solubility, low bioavailability, poor stability, and adverse drug effects. So far, GA has been utilized to develop a variety of active derivatives with improved water solubility and bioavailability through structural modification. This article summarized the progress in pharmaceutical chemistry of GA derivatives to provide a reference and basis for further study on structural modifications of GA and expansion of its clinical applications.