Gambogenic acid inhibits the proliferation of small‑cell lung cancer cells by arresting the cell cycle and inducing apoptosis

Natural products targeting autophagy and apoptosis in NSCLC: a novel therapeutic strategy

Lung cancer is the leading cause of cancer-related mortality worldwide, with non-small cell lung cancer (NSCLC) being the predominant type. The roles of autophagy and apoptosis in NSCLC present a dual and intricate nature. Additionally, autophagy and apoptosis interconnect through diverse crosstalk molecules. Owing to their multitargeting nature, safety, and efficacy, natural products have emerged as principal sources for NSCLC therapeutic candidates. This review begins with an exploration of the mechanisms of autophagy and apoptosis, proceeds to examine the crosstalk molecules between these processes, and outlines their implications and interactions in NSCLC. Finally, the paper reviews natural products that have been intensively studied against NSCLC targeting autophagy and apoptosis, and summarizes in detail the four most retrieved representative drugs. This paper clarifies good therapeutic effects of natural products in NSCLC by targeting autophagy and apoptosis and aims to promote greater consideration by researchers of natural products as candidates for anti-NSCLC drug discovery.

Multi-spectroscopic and in silico investigation of gambogic acid-calf thymus DNA interactions

Gambogic acid (GA), a xanthanoid compound, is derived from Garcinia Hanbury gamboge resin. Studying GA's DNA binding and targeting processes is crucial to understanding its tumor-targeting potentiality. This study used spectroscopic and in silico methods to investigate the GA-calf thymus DNA-binding interaction. The results of the UV-visible absorbance spectroscopy revealed that GA binds to DNA and forms a complex. Investigation of fluorescence quenching using ethidium bromide-DNA revealed that GA displaced ethidium bromide, and the type of quenching was static in nature, as determined by Stern-Volmer plot data. Thermodynamic analysis of the DNA-GA complex revealed a spontaneous, favorable interaction involving hydrogen bonding and hydrophobic interactions. Quenching experiments with potassium iodide, Acridine orange, and NaCl verified GA's groove-binding nature and the presence of weak electrostatic interactions. The thermal melting temperature of DNA in its native and bound states with GA did not differ significantly (69.27° C to 71.25° C), validating the binding of GA to the groove region. Furthermore, the groove-binding nature of GA was confirmed by studying its interaction with ssDNA and DNA viscosity. The methods of DSC, FT-IR, and CD spectroscopy have not revealed any structural aberrations in DNA bound with GA. Molecular docking and modeling studies revealed that GA has a groove-binding nature with DNA, which is consistent with prior experimental results. Finally, the findings shed information by which GA attaches to DNA and provide insights into its recognized anticancer effects via topoisomerase inhibition causing DNA cleavage, inhibition of cell proliferation and apoptosis.Communicated by Ramaswamy H. Sarma.

Caged Polyprenylated Xanthones in Garcinia hanburyi and the Biological Activities of Them

The previous phytochemical analyses of Garcinia hanburyi revealed that the main structural characteristic associated with its biological activity is the caged polyprenylated xanthones with a unique 4-oxatricyclo [4.3.1.03,7] dec-2-one scaffold, which contains a highly substituted tetrahydrofuran ring with three quaternary carbons. Based on the progress in research of the chemical constituents, pharmacological effects and modification methods of the caged polyprenylated xanthones, this paper presents a preliminary predictive analysis of their drug-like properties based on the absorption, distribution, metabolism, excretion and toxicity (ADME/T) properties. It was found out that these compounds have very similar pharmacokinetic properties because they possess the same caged xanthone structure, the 9,10-double bond in a,b-unsaturated ketones are critical for the antitumor activity. The author believes that there is an urgent need to seek new breakthroughs in the study of these caged polyprenylated xanthones. Thus, the research on the route of administration, therapeutic effect, structural modification and development of such active ingredients is of great interest. It is hoped that this paper will provide ideas for researchers to develop and utilize the active ingredients derived from natural products.

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.

Gambogenic Acid Inhibits Invasion and Metastasis of Melanoma through Regulation of lncRNA MEG3

Cutaneous melanoma is an aggressive cancer, which is the most common type of melanoma. In our previous studies, gambogenic acid (GNA) inhibited the proliferation and migration of melanoma cells. Maternally expressed gene 3 (MEG3) is a long noncoding RNA (lncRNA) that has been shown to have inhibitory effects in a variety of cancers. However, the mechanisms in melanoma progression need to be further investigated. In the current study, we investigated the inhibitory effect of GNA on melanoma and its molecular mechanism through a series of cell and animal experiments. We found that GNA could improve epithelial mesenchymal transition by up-regulating the expression of the lncRNA MEG3 gene, thereby inhibiting melanoma metastasis in vitro and in vivo.

Gambogenic Acid Induces Endoplasmic Reticulum Stress in Colorectal Cancer via the Aurora A Pathway

Colorectal cancer (CRC) is one of the most common malignancies in the world and has a poor prognosis. In the present research, gambogenic acid (GNA), isolated from the traditional Chinese medicine gamboge, markedly induced apoptosis and inhibited the proliferation of CRC in vitro and in vivo. Furthermore, GNA triggered endoplasmic reticulum (ER) stress, which subsequently activated inositol-requiring enzyme (IRE) 1α and the eukaryotic translation initiation factor (eIF) 2α pathway. Pretreatment with salubrinal (an eIF2α inhibitor) rescued GNA-induced cell death. Furthermore, GNA downregulated the expression of Aurora A. The Aurora A inhibitor alisertib decreased ER stress. In human colorectal adenocarcinoma tissue, Aurora A was upregulated compared to normal colorectal epithelial nuclei. Furthermore, GNA ameliorated mouse colitis-associated cancer models. Our findings demonstrated that GNA significantly inhibited the proliferation of CRC through activation of ER stress by regulating Aurora A, which indicates the potential of GNA for preventing the progression of CRC.

Gambogic acid and gambogenic acid induce a thiol-dependent heat shock response and disrupt the interaction between HSP90 and HSF1 or HSF2

Cancer cells rely on heat shock proteins (HSPs) for growth and survival. Especially HSP90 has multiple client proteins and plays a critical role in malignant transformation, and therefore different types of HSP90 inhibitors are being developed. The bioactive natural compound gambogic acid (GB) is a prenylated xanthone with antitumor activity, and it has been proposed to function as an HSP90 inhibitor. However, there are contradicting reports whether GB induces a heat shock response (HSR), which is cytoprotective for cancer cells and therefore a potentially problematic feature for an anticancer drug. In this study, we show that GB and a structurally related compound, called gambogenic acid (GBA), induce a robust HSR, in a thiol-dependent manner. Using heat shock factor 1 (HSF1) or HSF2 knockout cells, we show that the GB or GBA-induced HSR is HSF1-dependent. Intriguingly, using closed form ATP-bound HSP90 mutants that can be co-precipitated with HSF1, a known facilitator of cancer, we show that also endogenous HSF2 co-precipitates with HSP90. GB and GBA treatment disrupt the interaction between HSP90 and HSF1 and HSP90 and HSF2. Our study implies that these compounds should be used cautiously if developed for cancer therapies, since GB and its derivative GBA are strong inducers of the HSR, in multiple cell types, by involving the dissociation of a HSP90-HSF1/HSF2 complex.

Oral Delivery of Gambogenic Acid by Functional Polydopamine Nanoparticles for Targeted Tumor Therapy

To enhance the water solubility, oral bioavailability, and tumor targeting of gambogenic acid (GNA), polydopamine nanoparticles (PDA NPs) were prepared to encapsulate and stabilize GNA surface modified by folic acid (FA) and then coated with sodium alginate (GNA@PDA-FA SA NPs) to achieve an antitumor effect by oral administration. GNA@PDA-FA SA NPs exhibited in vitro pH-sensitive release behavior. In vitro cell studies manifested that GNA@PDA-FA NPs had higher cytotoxicity to 4T1 cells compared with raw GNA (IC₅₀ = 2.58 μM vs 7.57 μM). After being modified with FA, GNA@PDA-FA NPs were taken up easily by 4T1 cells. In vivo studies demonstrated that the area under the curve (AUC_0→∞) of the plasma drug concentration-time of GNA@PDA-FA SA NPs was 2.97-fold higher than that of raw GNA, along with improving drug distribution in the liver, lung, and kidney tissues. In vivo anti-tumor experiments, GNA@PDA-FA SA NPs significantly inhibited the growth of breast tumors in the 4T1 xenograft breast cancer model via oral administration without obvious toxicity on major organs. Our studies indicated that the GNA@PDA-FA SA NPs modified with FA and coated with SA were a promising drug delivery system for targeting tumor therapy via oral administration.

Gambogenic acid exerts anticancer effects in cisplatin‑resistant non‑small cell lung cancer cells

Non‑small cell lung cancer (NSCLC) is the most common type of lung cancer and the most common cause of mortality in patients with lung cancer. The efficacy of cisplatin‑based chemotherapy in NSCLC is limited by drug resistance, therefore, the development of novel anticancer agents is required to overcome cisplatin resistance. The present study investigated the anticancer activity of gambogenic acid (GNA), derived from gamboge, in the cisplatin‑resistant NSCLC cell line A549/Cis. GNA was revealed to have a potent inhibitory effect on cell growth in A549/Cis cells by blocking the cell cycle and inducing apoptosis. The investigation of the molecular mechanisms identified that GNA arrested the cell cycle at the G1 phase through the downregulation of cyclin Ds, cyclin dependent kinase (CDK)4 and CDK6, and the upregulation of p53 and p21. In addition, GNA induced apoptosis by increasing the activation of caspase 3 and caspase 7, in addition to the cleavage of poly(ADP‑ribose) polymerase. The results of the present study supported the potential application of GNA in cisplatin‑resistant NSCLC.

Effects of Rolling-Sliding Mechanical Stimulation on Cartilage Preserved In Vitro

Introduction

Mechanical stimulation is important for maintaining cartilage function. We used a loading device to exert rolling-sliding mechanical stimulation on cartilage preserved in vitro to investigate cartilage viability and the involved mechanisms.

Methods

Osteochondral grafts from pig knees were randomly classified into loading and control groups. The loading group cartilage was subjected to cycles of mechanical stimulation with specified frequency/time/pressure combinations every 3 days; Then the DMEM was refreshed, and the cartilage was preserved in vitro. The control group cartilage was preserved in DMEM throughout the process and was changed every 3 days. On days 14 and 28, the chondrocyte survival rate, histology, and Young's modulus of the cartilage were measured. Western blots were performed after 2 h of loading to evaluate the protein expression.

Results

The loading group showed a significantly higher chondrocyte survival rate, proteoglycan and type II collagen content, and Young's modulus than did the control group on day 14, but no statistically significant differences were found on day 28. After two hours of the loading, the phosphorylation levels of MEK and ERK1/2 increased, and the expression of caspase-3, cleaved caspase-3 and bax decreased.

Conclusion

These results suggest that periodic rolling-sliding mechanical stimulation can increase cartilage vitality in 2 weeks; a possible mechanism is that mechanical stimulation activates the MEK/ERK signalling pathway, thus inhibiting apoptotic protein expression. This loading preservation scheme could be used by cartilage tissue banks to improve cartilage preservation in vitro and enhance the quality of cartilage repair.