SSPH I, a Novel Anti-Cancer Saponin, Inhibits Autophagy and Induces Apoptosis via ROS Accumulation and ERK1/2 Signaling Pathway in Hepatocellular Carcinoma Cells

A systematic review of spirostanol saponins and anticancer natural products isolated from Tacca plantaginea (Hance) Drenth

The plant genus Tacca comprises twenty species including Tacca plantaginea, essentially distributed in the Indo-China region. Medicinal preparations from the rhizomes are used traditionally to treat gastrointestinal ailments, stomach aches and inflammatory disorders. A variety of bioactive molecules have been isolated from T. plantaginea, including potent anticancer steroids such as the taccanolides which interfere with microtubules dynamic. Other efficient anticancer natural products have been isolated from the plant, in particular a series of diosgenin/yamogenin-type sapogenins including taccaoside (monodesmosidic) and taccaoside A (bidesmosidic). Taccaoside A displays marked anticancer properties through two complementary mechanisms: a direct action on cancer stem cells via HRas and Pi3K/Akt signaling and an indirect immunomodulatory action via activation of cytotoxic T cells. A similar mechanism of action has been invoked with a total saponin extract from Schizocapsa plantaginea Hance (synonym to T. plantaginea) and the saponin SSPH 1. This saponin reduced tumor growth in mice through stimulation of cytotoxic T lymphocytes. Other bioactive products have been isolated from T. plantaginea, including withanolide-type steroids (plantagiolides, chantriolides), diarylheptanoids (plantagineosides) and different saponins (diosbulbisides, lieguonins). The discussion centers around the mechanism of action of spirostanol saponins, with the objective to promote their study as immuno-active anticancer agents.

Saponin Ⅰ from Shuitianqi () inhibits metastasis by negatively regulating the transforming growth factor-β1/Smad7 network and epithelial-mesenchymal transition in the intrahepatic metastasis Bagg's Albino/c mouse model

OBJECTIVE

To examine the influence of Saponin I from Shuitianqi (Rhizoma Schizocapasae Plantagineae) (SSPH I) on hepatocellular carcinoma (HCC) metastasis, and to elucidate the underlying mechanism.

METHODS

The intrahepatic metastasis Bagg's Albino/c (BALB/c) mouse model was established with human hepatocellular carcinomas (HepG2) cells, then treated with normal saline (once per day), cisplatin (2 mg/kg, once every 2 d), and SSPH Ⅰ (25, 50, and 75 mg/kg, once per day). Then, we assessed alterations in the hepatic pathology and target protein expressions in the intrahepatic metastasis BALB/c mouse model using a series of molecular biology techniques.

RESULTS

Based on our analysis, SSPH Ⅰ significantly alleviated hepatocyte necrosis and tumor cells infiltration. Moreover, SSPH Ⅰ suppressed extracellular matrix (ECM) degradation and angiogenesis viaa decrease in matrix etalloproteinase-2 (MMP-2), MMP-9, CD31, CD34, and vascular endothelial growth factor (VEGF) levels. Furthermore, SSPH Ⅰ repressed invasion and meta-stasis by suppressing the transforming growth factor-β1 (TGF-β1)/Smad7 axis and epithelial-mesenchymal transition (EMT), as evidenced by the scarce TGF-β1, N-cadherin, and Vimentin expressions, and elevated Smad7 and E-cadherin expressions.

CONCLUSION

The SSPH Ⅰ-mediated negative regulation of the TGF-β1/Smad7 axis and EMT are critical for the inhibition of HCC invasion and metastasis.

Blockage of Autophagy for Cancer Therapy: A Comprehensive Review

The incidence and mortality of cancer are increasing, making it a leading cause of death worldwide. Conventional treatments such as surgery, radiotherapy, and chemotherapy face significant limitations due to therapeutic resistance. Autophagy, a cellular self-degradation mechanism, plays a crucial role in cancer development, drug resistance, and treatment. This review investigates the potential of autophagy inhibition as a therapeutic strategy for cancer. A systematic search was conducted on Embase, PubMed, and Google Scholar databases from 1967 to 2024 to identify studies on autophagy inhibitors and their mechanisms in cancer therapy. The review includes original articles utilizing in vitro and in vivo experimental methods, literature reviews, and clinical trials. Key terms used were "Autophagy", "Inhibitors", "Molecular mechanism", "Cancer therapy", and "Clinical trials". Autophagy inhibitors such as chloroquine (CQ) and hydroxychloroquine (HCQ) have shown promise in preclinical studies by inhibiting lysosomal acidification and preventing autophagosome degradation. Other inhibitors like wortmannin and SAR405 target specific components of the autophagy pathway. Combining these inhibitors with chemotherapy has demonstrated enhanced efficacy, making cancer cells more susceptible to cytotoxic agents. Clinical trials involving CQ and HCQ have shown encouraging results, although further investigation is needed to optimize their use in cancer therapy. Autophagy exhibits a dual role in cancer, functioning as both a survival mechanism and a cell death pathway. Targeting autophagy presents a viable strategy for cancer therapy, particularly when integrated with existing treatments. However, the complexity of autophagy regulation and the potential side effects necessitate further research to develop precise and context-specific therapeutic approaches.

Ferroptosis in Cancer Therapy: Mechanisms, Small Molecule Inducers, and Novel Approaches

Ferroptosis, a unique form of programmed cell death, is initiated by an excess of iron accumulation and lipid peroxidation-induced damage. There is a growing body of evidence indicating that ferroptosis plays a critical role in the advancement of tumors. The increased metabolic activity and higher iron levels in tumor cells make them particularly vulnerable to ferroptosis. As a result, the targeted induction of ferroptosis is becoming an increasingly promising approach for cancer treatment. This review offers an overview of the regulatory mechanisms of ferroptosis, delves into the mechanism of action of traditional small molecule ferroptosis inducers and their effects on various tumors. In addition, the latest progress in inducing ferroptosis using new means such as proteolysis-targeting chimeras (PROTACs), photodynamic therapy (PDT), sonodynamic therapy (SDT) and nanomaterials is summarized. Finally, this review discusses the challenges and opportunities in the development of ferroptosis-inducing agents, focusing on discovering new targets, improving selectivity, and reducing toxic and side effects.

Ferroptosis targeting natural compounds as a promising approach for developing potent liver cancer agents

Liver cancer is the second leading cause of cancer-related death worldwide. However, treatment options, including surgical resection, transplantation, and molecular drug therapies, are of limited effectiveness. Recent studies have demonstrated that suppressing ferroptosis might be a pivotal signal for liver cancer initiation, thus providing a new way to combat liver cancer. Ferroptosis is a distinct form of controlled cell death that differs from conventional cell death routes like apoptosis, necrosis, and pyroptosis. It results from intracellular iron overload, which raises iron-dependent reactive oxygen species. This, in turn, leads to the accumulation of lipid peroxides that further result in oxidative damage to cell membranes, disrupt normal functioning, and ultimately speed up the ferroptosis phenomenon. Ferroptosis regulation is intricately linked to cellular physiological processes, encompassing iron metabolism, lipid metabolism, and the equilibrium between oxygen-free radical reactions and lipid peroxidation. This review intends to summarize the natural compounds targeting ferroptosis in liver cancer to offer new therapeutic ideas for liver cancer. Furthermore, it serves as the foundation for identifying and applying chemical medicines and natural chemicals that target ferroptosis to treat liver cancer efficiently.

Natural products targeting macroautophagy signaling in hepatocellular carcinoma therapy: Recent evidence and perspectives

Hepatocellular carcinoma (HCC), presently the second leading cause of global cancer-related mortality, continues to pose significant challenges in the realm of medical oncology, impacting both clinical drug selection and mechanistic research. Recent investigations have unveiled autophagy-related signaling as a promising avenue for HCC treatment. A growing body of research has highlighted the pivotal role of autophagy-modulating natural products in inhibiting HCC progression. In this context, we provide a concise overview of the fundamental autophagy mechanism and delineate the involvement of autophagic signaling pathways in HCC development. Additionally, we review pertinent studies demonstrating how natural products regulate autophagy to mitigate HCC. Our findings indicate that natural products exhibit cytotoxic effects through the induction of excessive autophagy, simultaneously impeding HCC cell proliferation by autophagy inhibition, thereby depriving HCC cells of essential energy. These effects have been associated with various signaling pathways, including PI3K/AKT, MAPK, AMPK, Wnt/β-catenin, Beclin-1, and ferroautophagy. These results underscore the considerable therapeutic potential of natural products in HCC treatment. However, it is important to note that the present study did not establish definitive thresholds for autophagy induction or inhibition by natural products. Further research in this domain is imperative to gain comprehensive insights into the dual role of autophagy, equipping us with a better understanding of this double-edged sword in HCC management.

Advanced oxidation protein products attenuate the autophagy-lysosome pathway in ovarian granulosa cells by modulating the ROS-dependent mTOR-TFEB pathway

Oxidative stress dysfunction has recently been found to be involved in the pathogenesis of premature ovarian insufficiency (POI). Previously, we found that advanced oxidation protein products (AOPPs) in plasma were elevated in women with POI and had an adverse effect on granulosa cell proliferation. However, the mechanism underlying the effects of AOPPs on autophagy-lysosome pathway regulation in granulosa cells remains unclear. In this study, the effect of AOPPs on autophagy and lysosomal biogenesis and the underlying mechanisms were explored by a series of in vitro experiments in KGN and COV434 cell lines. AOPP-treated rat models were employed to determine the negative effect of AOPPs on the autophagy-lysosome systems in vivo. We found that increased AOPP levels activated the mammalian target of rapamycin (mTOR) pathway, and inhibited the autophagic response and lysosomal biogenesis in KGN and COV434 cells. Furthermore, scavenging of reactive oxygen species (ROS) with N-acetylcysteine and blockade of the mTOR pathway with rapamycin or via starvation alleviated the AOPP-induced inhibitory effects on autophagy and lysosomal biogenesis, suggesting that these effects of AOPPs are ROS-mTOR dependent. The protein expression and nuclear translocation of transcription factor EB (TFEB), the key regulator of lysosomal and autophagic function, were also impaired by the AOPP-activated ROS-mTOR pathway. In addition, TFEB overexpression attenuated the AOPP-induced impairment of autophagic flux and lysosomal biogenesis in KGN and COV434 cells. Chronic AOPP stimulation in vivo also impaired autophagy and lysosomal biogenesis in granulosa cells of rat ovaries. The results highlight that AOPPs lead to impairment of autophagic flux and lysosomal biogenesis via ROS-mTOR-TFEB signaling in granulosa cells and participate in the pathogenesis of POI.

SSPH I, A Novel Anti-cancer Saponin, Inhibits EMT and Invasion and Migration of NSCLC by Suppressing MAPK/ERK1/2 and PI3K/AKT/ mTOR Signaling Pathways

BACKGROUND

Saponin of Schizocapsa plantaginea Hance I (SSPH I).a bioactive saponin found in Schizocapsa plantaginea, exhibits significant anti-proliferation and antimetastasis in lung cancer.

OBJECTIVE

To explore the anti-metastatic effects of SSPH I on non-small cell lung cancer (NSCLC) with emphasis on epithelial-mesenchymal transition (EMT) both in vitro and in vivo.

METHODS

The effects of SSPH I at the concentrations of 0, 0.875,1.75, and 3.5 μM on A549 and PC9 lung cancer cells were evaluated using colony formation assay, CCK-8 assay, transwell assay and wound-healing assay. The actin cytoskeleton reorganization of PC9 and A549 cells was detected using the FITC-phalloidin fluorescence staining assay. The proteins related to EMT (N-cadherin, E-cadherin and vimentin), p- PI3K, p- AKT, p- mTOR and p- ERK1/2 were detected by Western blotting. A mouse model of lung cancer metastasis was established by utilizing 95-D cells, and the mice were treated with SSPH I by gavage.

RESULTS

The results suggested that SSPH I significantly inhibited the migration and invasion of NSCLC cells under a non-cytotoxic concentration. Furthermore, SSPH I at a non-toxic concentration of 0.875 μM inhibited F-actin cytoskeleton organization. Importantly, attenuation of EMT was observed in A549 cells with upregulation in the expression of epithelial cell marker E-cadherin and downregulation of the mesenchymal cell markers vimentin as well as Ncadherin. Mechanistic studies revealed that SSPH I inhibited MAPK/ERK1/2 and PI3K/AKT/mTOR signaling pathways.

CONCLUSION

SSPH I inhibited EMT, migration, and invasion of NSCLC cells by suppressing MAPK/ERK1/2 and PI3K/AKT/mTOR signaling pathways, suggesting that the natural compound SSPH I could be used for inhibiting metastasis of NSCLC.

Steroidal saponin SSPH I induces ferroptosis in HepG2 cells via regulating iron metabolism

Hepatocellular carcinoma (HCC) is a common type of solid liver carcinoma. Regulating ferroptosis is important for the treatment of HCC. SSPH I is an anti-HCC steroidal saponin isolated from Schizocapsa plantaginea Hance. In this study, we found that SSPH I exerted significant anti-proliferation and anti-migration effects on HepG2 cell, ferroptosis inhibitor ferrostatin-1 or iron chelator ciclopirox partly attenuated the effect of SSPH I. SSPH I also induced apoptosis and G2/M phase cell cycle arrest. ROS accumulation, glutathione depletion and malondialdehyde accumulation were detected after SSPH I treatment, which leads to lipid peroxidation. Ferrostatin-1 or ciclopirox showed a significant antagonist effect towards SSPH I induced lipid peroxidation. Furthermore, typical morphologic changes of ferroptosis, such as increasing density of mitochondrial membrane and reduction of mitochondrial cristae were observed in HepG2 cells after SSPH I treatment. SSPH I does not regulate the xCT protein. Interestingly, SSPH I elevated the expression levels of SLC7A5, which is the negative regulator of ferroptosis. In contrast, SSPH I upregulated the expression of TFR and Fpn proteins, leading to the accumulation of Fe²⁺. Ferrostatin-1 and ciclopirox presented a similar antagonist effect on SSPH I. In conclusion, our research first reveals that SSPH I induced ferroptosis in HepG2 cells. In addition, our results suggest that SSPH I induces ferroptosis by causing iron overload in HepG2 cells.

Optimization of Total Saponin Extraction from Polyscias fruticosa Roots Using the Ultrasonic-Assisted Method and Response Surface Methodology

Polyscias fruticosa (L.) Harms is commonly used for medicinal purposes in Vietnam. In traditional medicine, the plant is used to cure ischemia, reduce inflammation, and increase cerebral blood circulation. Triterpene saponins are the major chemical constituents found in the roots of P. fruticosa. This compound exhibited a broad spectrum of biological effects, including lowering blood sugar, suppressing tumor growth and inflammation. This study focused on optimizing the process of total saponins extraction from P. fruticosa roots using the ultrasonic-assisted extraction (UAE) method, ethanol solvent and response surface methodology, and Box–Behnken design model, then evaluating the cytotoxic effect against some cancer cell lines. The results showed that under the optimal conditions, including an extraction temperature of 60 °C and ultrasonic power of 185 W in 65 min, the maximum extraction yield and total saponin content were 14.51 ± 1.15% and 41.24 ± 1.68 mg/g, respectively. Moreover, the saponin extract had cytotoxic effects against A549, HepG2, PC-3, and Hela. The results of this study confirmed that triterpene saponin is an important chemical component which is present in a high content in P. fruticosa roots and gives rise to significant biological activities. In addition, UAE can be used as a highly efficient method for triterpene saponins extraction from P. fruticosa roots.

Network pharmacology-based approach uncovers the JAK/STAT signaling mechanism underlying paederia scandens extract treatment of rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a common autoimmune disease. Paederia scandens (Lour.) Merr is a common folk remedy used in Hainan, China, to dispel the wind and dampness associated with RA.

METHODS

The active components of Paederia scandens were extracted using network pharmacology. The potential targets of active components were used to determine activated pathways, and the in vitro effects of Paederia scandens extracts were verified in RA fibroblast-like synoviocytes (HFLS-RA).

RESULTS

We identified 27 active components using ultra-high-performance liquid chromatography (UHPLC)-quadrupole time-of-flight (QTOF)-mass spectrometry (MS). Among the major target genes with high connectivity, IL-1β, PI3K, TNF, and JAK2 are known to play key roles in RA development. High-affinity interactions were identified between active compounds in Paederia scandens extract and Janus kinase JAK 2, which are key components of the JAK-signal transducer and activator of transcription (STAT) signaling pathway. In HFLS-RA cells, Paederia scandens extract treatment reduced the mRNA levels of IL-6, IL-1β, and IL-17. Paederia scandens extract treatment also significantly inhibited the phosphorylation of JAK 2 and STAT3, regulating cell proliferation.

CONCLUSIONS

Based on these results, we confirmed that Paederia scandens has potential for application as a therapeutic and preventive food and acts through the modulation and suppression of JAK-STAT pathway activation to control the inflammatory response in RA.

Autophagy is involved in Ficus carica fruit extract-induced anti-tumor effects on pancreatic cancer

Pancreatic cancer (PaCa), a common and highly lethal malignant cancer, is often insensitive to radio- and/or chemotherapy. Therefore, effective treatment regiments are still lacking. Herein, we found that an extract of Ficus carica fruit (EFCF) exerted anti-tumor effects on PaCa cells. EFCF induced cell viability inhibition and apoptotic cell death in two PaCa cell lines in a dose- and time dependent manner. EFCF effectively suppressed the migration, metastasis, invasion, and colony formation of PaCa cells. Mechanistically, EFCF stimulated an increase in intracellular ROS to promote cell death and senescence. EFCF treatment also triggered autophagy, and autophagy inhibition enhanced EFCF-induced cell death. We found that EFCF decreased mitochondrial membrane potential and promoted lipid peroxidation. Moreover, intragastric administration of EFCF effectively suppressed xenograft PaCa growth inhibition by activating cell death. EFCF had no apparent toxicity to normal pancreatic epithelial cells. Together, these findings suggest that EFCF may be a potential treatment for PaCa.

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.

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.

Targeting autophagy using saponins as a therapeutic and preventive strategy against human diseases

Autophagy is a ubiquitous mechanism for maintaining cellular homeostasis through the degradation of long-lived proteins, insoluble protein aggregates, and superfluous or damaged organelles. Dysfunctional autophagy is observed in a variety of human diseases. With advanced research into the role that autophagy plays in physiological and pathological conditions, targeting autophagy is becoming a novel tactic for disease management. Saponins are naturally occurring glycosides containing triterpenoids or steroidal sapogenins as aglycones, and some saponins are reported to modulate autophagy. Research suggests that saponins may have therapeutic and preventive efficacy against many autophagy-related diseases. Therefore, this review comprehensively summarizes and discusses the reported saponins that exhibit autophagy regulating activities. In addition, the relevant signaling pathways that the mechanisms involved in regulating autophagy and the targeted diseases were also discussed. By regulating autophagy and related pathways, saponins exhibit bioactivities against cancer, neurodegenerative diseases, atherosclerosis and other cardiac diseases, kidney diseases, liver diseases, acute pancreatitis, and osteoporosis. This review provides an overview of the autophagy-regulating activity of saponins, the underlying mechanisms and potential applications for managing various diseases.