Calotropin from Asclepias curasavica induces cell cycle arrest and apoptosis in cisplatin-resistant lung cancer cells

Energy metabolism as the hub of advanced non-small cell lung cancer management: a comprehensive view in the framework of predictive, preventive, and personalized medicine

Energy metabolism is a hub of governing all processes at cellular and organismal levels such as, on one hand, reparable vs. irreparable cell damage, cell fate (proliferation, survival, apoptosis, malignant transformation etc.), and, on the other hand, carcinogenesis, tumor development, progression and metastazing versus anti-cancer protection and cure. The orchestrator is the mitochondria who produce, store and invest energy, conduct intracellular and systemically relevant signals decisive for internal and environmental stress adaptation, and coordinate corresponding processes at cellular and organismal levels. Consequently, the quality of mitochondrial health and homeostasis is a reliable target for health risk assessment at the stage of reversible damage to the health followed by cost-effective personalized protection against health-to-disease transition as well as for targeted protection against the disease progression (secondary care of cancer patients against growing primary tumors and metastatic disease). The energy reprogramming of non-small cell lung cancer (NSCLC) attracts particular attention as clinically relevant and instrumental for the paradigm change from reactive medical services to predictive, preventive and personalized medicine (3PM). This article provides a detailed overview towards mechanisms and biological pathways involving metabolic reprogramming (MR) with respect to inhibiting the synthesis of biomolecules and blocking common NSCLC metabolic pathways as anti-NSCLC therapeutic strategies. For instance, mitophagy recycles macromolecules to yield mitochondrial substrates for energy homeostasis and nucleotide synthesis. Histone modification and DNA methylation can predict the onset of diseases, and plasma C7 analysis is an efficient medical service potentially resulting in an optimized healthcare economy in corresponding areas. The MEMP scoring provides the guidance for immunotherapy, prognostic assessment, and anti-cancer drug development. Metabolite sensing mechanisms of nutrients and their derivatives are potential MR-related therapy in NSCLC. Moreover, miR-495-3p reprogramming of sphingolipid rheostat by targeting Sphk1, 22/FOXM1 axis regulation, and A2 receptor antagonist are highly promising therapy strategies. TFEB as a biomarker in predicting immune checkpoint blockade and redox-related lncRNA prognostic signature (redox-LPS) are considered reliable predictive approaches. Finally, exemplified in this article metabolic phenotyping is instrumental for innovative population screening, health risk assessment, predictive multi-level diagnostics, targeted prevention, and treatment algorithms tailored to personalized patient profiles-all are essential pillars in the paradigm change from reactive medical services to 3PM approach in overall management of lung cancers. This article highlights the 3PM relevant innovation focused on energy metabolism as the hub to advance NSCLC management benefiting vulnerable subpopulations, affected patients, and healthcare at large.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00357-5.

From immune checkpoints to therapies: understanding immune checkpoint regulation and the influence of natural products and traditional medicine on immune checkpoint and immunotherapy in lung cancer

Lung cancer is a disease of global concern, and immunotherapy has brought lung cancer therapy to a new era. Besides promising effects in the clinical use of immune checkpoint inhibitors, immune-related adverse events (irAEs) and low response rates are problems unsolved. Natural products and traditional medicine with an immune-modulating nature have the property to influence immune checkpoint expression and can improve immunotherapy's effect with relatively low toxicity. This review summarizes currently approved immunotherapy and the current mechanisms known to regulate immune checkpoint expression in lung cancer. It lists natural products and traditional medicine capable of influencing immune checkpoints or synergizing with immunotherapy in lung cancer, exploring both their effects and underlying mechanisms. Future research on immune checkpoint modulation and immunotherapy combination applying natural products and traditional medicine will be based on a deeper understanding of their mechanisms regulating immune checkpoints. Continued exploration of natural products and traditional medicine holds the potential to enhance the efficacy and reduce the adverse reactions of immunotherapy.

Unveiling the anti-cancer mechanisms of calotropin: Insights into cell growth inhibition, cell cycle arrest, and metabolic regulation in human oral squamous carcinoma cells (HSC-3)

Background

Calotropin, a cardiac glycoside obtained from the plant Calotropis gigantea, has demonstrated promising potential as an anti-tumorigenesis compound.

Objective

The main objective of this study was to investigate the potential anti-cancer properties of calotropin against HSC-3 oral squamous cancer cells and to elucidate the underlying mechanisms involved in its action.

Material and method

Calotropin were treated in HSC-3 to evaluate cell viability by MTT assay. Flow cytometry analysis divulged that calotropin G0/G1 phase cell cycle arrest and apoptosis in HSC-3 cells. Calotropin displayed inhibitory properties against aerobic glycolysis, a metabolic alteration using glucose uptaken, lactose production and LDHA activity assays. Furthermore, migration and invasion assays help that calotropin has ability to reduce the migratory and invasive of HSC-3 cells, using transwell and Matrigel assay. Validation of mRNA expression through RT-PCR. Molecular docking was implemented to validate the binding association of calotropin with apoptosis and metastatic regulating targets.

Result

The results exemplify that increasing doses of calotropin effectively hold back the HSC-3 cell progression. Migration and invasion assays help that calotropin has ability to reduce the migratory and invasive of HSC-3 cells, indicating its potential to inhibit cancer metastasis. These results imply that calotropin may influence genes linked to metastasis and apoptosis in order to achieve its beneficial effects on cancer. Docking results provided further support, showing a high binding energy between calotropin and metastasis-mediated pathways.

Conclusion

Overall, our findings shed an experimental evidence on how calotropin inhibits the HSC-3 oral squamous cancer cell growth, highlighting the drug's potential as a treatment for oral cancer. Further, investigation on in-vivo experiment is warranted to explore its potential mechanism of action and to develop a novel drug towards clinical trial.

An updated pharmacological insight into calotropin as a potential therapeutic agent in cancer

Calotropin is a pharmacologically active compound isolated from milkweed plants like Calotropis procera, Calotropis gigantea, and Asclepias currasavica that belong to the Asclepiadaceae family. All of these plants are recognised as medical traditional plants used in Asian countries. Calotropin is identified as a highly potent cardenolide that has a similar chemical structure to cardiac glycosides (such as digoxin and digitoxin). During the last few years, cytotoxic and antitumor effects of cardenolides glycosides have been reported more frequently. Among cardenolides, calotropin is identified as the most promising agent. In this updated and comprehensive review, we aimed to analyze and discuss the specific mechanisms and molecular targets of calotropin in cancer treatment to open new perspectives for the adjuvant treatment of different types of cancer. The effects of calotropin on cancer have been extensively studied in preclinical pharmacological studies in vitro using cancer cell lines and in vivo in experimental animal models that have targeted antitumor mechanisms and anticancer signaling pathways. The analyzed information from the specialized literature was obtained from scientific databases until December 2022, mainly from PubMed/MedLine, Google Scholar, Scopus, Web of Science, and Science Direct databases using specific MeSH search terms. The results of our analysis demonstrate that calotropin can be a potential chemotherapeutic/chemopreventive adjunctive agent in cancer pharmacotherapeutic management.

Calotropin and corotoxigenin 3-O-glucopyranoside from the desert milkweed Asclepias subulata inhibit the Na+/K+-ATPase activity

Na⁺/K⁺-ATPase is an essential transmembrane enzyme found in all mammalian cells with critical functions for cell ion homeostasis. The inhibition of this enzyme by several cardiotonic steroids (CTS) has been associated with the cytotoxic effect on cancer cell lines of phytochemicals such as ouabain and digitoxin. This study evaluated the inhibitory capacity of cardenolides calotropin and corotoxigenin 3-O-glucopyranoside (C3OG) from Asclepias subulata over the Na⁺/K⁺-ATPase activity in vitro and silico. The inhibitory assays showed that calotropin and C3OG decreased the Na⁺/K⁺-ATPase activity with IC₅₀ values of 0.27 and 0.87 μM, respectively. Furthermore, the molecules presented an uncompetitive inhibition on Na⁺/K⁺-ATPase activity, with K_i values of 0.2 μM to calotropin and 0.5 μM to C3OG. Furthermore, the molecular modeling indicated that calotropin and C3OG might interact with the Thr⁷⁹⁷ and Gln¹¹¹ residues, considered essential to the interaction with the Na⁺/K⁺-ATPase. Besides, these cardenolides can interact with amino acid residues such as Phe⁷⁸³, Leu¹²⁵, and Ala³²³, to establish hydrophobic interactions on the binding site. Considering the results, these provide novel evidence about the mechanism of action of cardenolides from A. subulata, proposing that C3OG is a novel cardenolide that deserves further consideration for in vitro cellular antiproliferative assays and in vivo studies as an anticancer molecule.

Screening of Promising Chemotherapeutic Candidates from Plants against Human Adult T-Cell Leukemia/Lymphoma (VI): Cardenolides from Asclepias curassavica

In the course of our screening program for novel chemotherapeutic candidates from plants against adult T-cell leukemia/lymphoma, the extracts of Asclepias curassavica L. showed potent activity against MT-1 and MT-2 cells. Therefore, we attempted to isolate their active components. We identified a new cardenolide, 19-dihydrocalactinic acid methyl ester (1), along with 16 known cardenolides (2-17). Their structures were determined on the basis of spectroscopic data. Almost all of the isolated cardenolides inhibited the growth of both tumor cell lines. All the doubly linked cardenolides (11-17) except for 14 showed more potent activity than the other cardenolides. A comparison of the activities of 11, 14 and 16 revealed that the presence of hydroxy or acetoxy functional groups at C-16 led to a decrease in the activity. The 50% effective concentration (EC₅₀) value of calotropin (11) against MT-2 cells was comparable to the potency of the clinical antineoplastic drug doxorubicin. The cytotoxic effect of 11 toward normal mononuclear cells obtained from the peripheral blood (PB-MNCs) was observed at a concentration 6 to 12 times higher than that used to induce growth inhibition against MT-1 and MT-2 cells. The proportions of annexin V-positive cells after 72 h of treatment with 11 were increased, indicating that it significantly induced apoptosis in MT-1 and MT-2 cells in a concentration-dependent manner. Cell cycle experiments demonstrated that 11 arrested MT-1 and MT-2 cells at the G2/M phase. Therefore, compound 11 may be a promising candidate for the treatment of adult T-cell leukemia/lymphoma.

Calotropis procera (Aiton) Dryand (Apocynaceae) as an anti-cancer agent against canine mammary tumor and osteosarcoma cells

Our goal was to evaluate phytochemical characterization and the antitumor potential of Calotropis procera. The phytochemical constitution of the crude extract (CE) revealed the presence of flavonoids, glycosides and cardenolide. The MTT assay was used to evaluate the cytotoxicity of CE, methanolic (MF) and ethyl acetate fractions (EAF) of C. procera in canine osteosarcoma cells (OST), canine mammary tumor (CMT), and canine skin fibroblasts (non-tumor cell). Doxorubicin was also used as a positive control. Results showed that CE, MF and EAF promoted a decrease in the viability of OST and CMT cells and did not alter the fibroblasts viability. C. procera also decreased the number of cells, corroborating to the decrease in proliferation and the cell cycle arrest in the G0/G1 phase. It was also evaluated the cell morphology by light and fluorescence microscopy, being demonstrated a reduction in cytoplasmic and cell rounding characteristic of programmed cell death. Moreover, flow cytometry data demonstrated that CE treatment promoted increase of caspase-3 and p53, showing that the cell death was activated in OST cells. In addition, there was a decrease in CD31, VEGF, osteopontin and TGF-β after CE treatment, suggesting that CE exerts its antitumor effect by reducing angiogenesis and tumor progression in OST cells. Moreover, CMT cells showed a reduction in PCNA after treatment with MF and CE. Analyzing the data together, C. procera, especially CE, showed an antitumor potential in both OST and CMT cells, encouraging us to continue investigating its use in cancer therapy.

Towards the synthesis of calotropin and related cardenolides from 3-epiandrosterone: A-ring related modifications

Calotropin and related cardiac glycosides isolated from plants such as calotropis gigantea represent an interesting target for biological investigations and are based on a cardiac steroid that is doubly connected to a sugar moiety.

Calotropin activates YAP through downregulation of LATS1 in colorectal cancer cells

Objectives: Calotropin (CTP), a natural product isolated from Calotropis gigantea, has been identified as a potential anticancer agent. In this study, we aimed to investigate the effect CTP on colorectal cancer and the role of Yes-associated protein (YAP) in CTP-inhibited cell proliferation.

Methods: Cell viability and cell proliferation were detected by MTT and BrdU assay. Western blotting and immunofluorescence were performed to determine CTP-induced YAP dephosphorylation and nuclear localization. Western blotting, siRNA transfection and RT-PCR analysis were carried out to investigate the mechanisms of CTP-mediated YAP activation. The anti-tumor activities of CTP were observed in mice tumor models.

Results: We demonstrated that CTP inhibits the proliferation of colorectal cancer cells both in vitro and in vivo. Moreover, we showed that CTP activates YAP in colorectal cancer cells. Mechanistically, CTP promotes LATS1 degradation via the ubiquitination/proteasome pathway, resulting in YAP dephosphorylation and nuclear localization, leading to induce YAP target genes expression in colorectal cancer cells. Inhibition of YAP activity enhances CTP-mediated inhibition of cell proliferation, suggesting that YAP plays a protective role in CTP-induced antiproliferative effect.

Conclusion: Our results demonstrate that CTP markedly inhibits tumor growth and activates a protective role of YAP in colorectal cancer cells, indicating that combination of CTP and YAP targeting drugs may be a promising strategy for colorectal cancer treatment.

Calotropin regulates the apoptosis of non‑small cell cancer by regulating the cytotoxic T‑lymphocyte associated antigen 4‑mediated TGF‑β/ERK signaling pathway

Non-small-cell lung cancer (NSCLC) is one of the most common malignancies that is responsible for a high level of cancer-associated mortalities worldwide. Previous evidence has shown that Calotropin is an upstream activator of protein kinase B, which can further inhibit the growth and promote the apoptosis of NSCLC cells. In the present study, the efficacy of Calotropin on growth, aggressiveness and apoptosis of NSCLC cells was investigated, as well as the potential underlying mechanism. The results demonstrated that Calotropin inhibited H358 cell growth, migration and invasion. Flow cytometry assay showed that Calotropin promoted the apoptosis of H358 cells in vitro. Western blot analysis demonstrated that Calotropin inhibited fibronectin (FN), Vimentin (VIM) and E-cadherin (Eca) protein expression levels in H358 cells in vitro. In addition, Calotropin treatment upregulated pro-apoptosis gene expression, including caspase-3, caspase-8 and apoptotic protease activating factor-1, and downregulated anti-apoptosis gene expression, including P53, B-cell lymphoma (Bcl) 2 and Bcl-2-like protein 2 in H358 cells. The results also revealed that the expression levels of cytotoxic T-lymphocyte associated antigen 4 (CTLA-4) were decreased by Calotropin treatment in H358 cells. Analyses of the underlying mechanism indicated that Calotropin inhibited transforming growth factor-β (TGF-β) and extracellular signal-regulated kinase (ERK) expression. Overexpression of CTLA-4 inhibited Calotropin-mediated downregulation of TGF-β and ERK expression in H358 cells. In vivo assay revealed that Calotropin administration significantly inhibited tumor growth and prolonged animal survival over the 120-day observation period. Immunohistochemistry demonstrated that the number of apoptotic cells increased and the expression levels of CTLA-4 were decreased in the Calotropin-treated tumor group when compared with control. In addition, the expression levels of TGF-β and ERK were downregulated in the Calotropin-treated tumor group compared with control. In conclusion, the results of the present study indicated that Calotropin administration regulated NSCLC apoptosis by downregulating the CTLA-4-mediated TGF-β/ERK signaling pathway, suggesting that Calotropin may be a potential anti-cancer agent for the treatment of NSCLC.

Anti-Tumor Effects of Atractylenolide-I on Human Ovarian Cancer Cells

Background

The aim of this study was to investigate the effects of Atractylenolide-I (AT-I), a naturally occurring sesquiterpene lactone isolated from Atractylodes macrocephala Koidz, on human ovarian cancer cells.

Material/Methods

The viability and anchorage-independent growth of ovarian cancer cells were evaluated using MTT and colony formation assay, respectively. Cell cycle and apoptosis were detected with flow cytometry analysis. The level of cyclin B1 and CDK1 was measured using qPCR and ELISA analysis. The expression of Bax, cleaved caspase-9, cleaved caspase-3, cytochrome c, AIF, and Bcl-2, and phosphorylation level of PI3K, AKT, and mTOR were determined with Western blot analysis.

Results

AT-I decreased the cell viability and suppressed anchorage-independent growth of A2780 cells. Cell cycle was arrested in G2/M phase transition by AT-I treatment, which was related to decreased expression of cyclin B1 and CDK1 in a dose-dependent manner. In addition, the treatment induced apoptosis, as shown by up-regulation of Bax, cleaved caspase-9, cleaved caspase-3, and cytosolic release of cytochrome c and AIF, and down-regulation of Bcl-2, in a dose-dependent manner. Then, the effects of AT-I on PI3K/Akt/mTOR pathways were examined to further investigate the underlying anti-cancer mechanism of AT-I, and the results showed that treatment with AT-I significantly decreased the phosphorylation level of PI3K, Akt, and mTOR.

Conclusions

This study demonstrated that AT-I induced cell cycle arrest and apoptosis through inhibition of PI3K/Akt/mTOR pathway in ovarian cancer cells. These results suggest that AT-I might be a potential therapeutic agent in the treatment of ovarian cancer.