mTOR inhibition of cardamonin on antiproliferation of A549 cells is involved in a FKBP12 independent fashion

From Plant to Chemistry: Sources of Active Opioid Antinociceptive Principles for Medicinal Chemistry and Drug Design

Pain continues to be an enormous global health challenge, with millions of new untreated or inadequately treated patients reported annually. With respect to current clinical applications, opioids remain the mainstay for the treatment of pain, although they are often associated with serious side effects. To optimize their tolerability profiles, medicinal chemistry continues to study novel ligands and innovative approaches. Among them, natural products are known to be a rich source of lead compounds for drug discovery, and they hold potential for pain management. Traditional medicine has had a long history in clinical practice due to the fact that nature provides a rich source of active principles. For instance, opium had been used for pain management until the 19th century when its individual components, such as morphine, were purified and identified. In this review article, we conducted a literature survey aimed at identifying natural products interacting either directly with opioid receptors or indirectly through other mechanisms controlling opioid receptor signaling, whose structures could be interesting from a drug design perspective.

Raptor mediates the selective inhibitory effect of cardamonin on RRAGC-mutant B cell lymphoma

BACKGROUND

mTORC1 (mechanistic target of rapamycin complex 1) is associated with lymphoma progression. Oncogenic RRAGC (Rag guanosine triphosphatase C) mutations identified in patients with follicular lymphoma facilitate the interaction between Raptor (regulatory protein associated with mTOR) and Rag GTPase. It promotes the activation of mTORC1 and accelerates lymphomagenesis. Cardamonin inhibits mTORC1 by decreasing the protein level of Raptor. In the present study, we investigated the inhibitory effect and possible mechanism of action of cardamonin in RRAGC-mutant lymphoma. This could provide a precise targeted therapy for lymphoma with RRAGC mutations.

METHODS

Cell viability was measured using a cell counting kit-8 (CCK-8) assay. Protein expression and phosphorylation levels were determined using western blotting. The interactions of mTOR and Raptor with RagC were determined by co-immunoprecipitation. Cells overexpressing RagC wild-type (RagCWT) and RagC Thr90Asn (RagCT90N) were generated by lentiviral infection. Raptor knockdown was performed by lentivirus-mediated shRNA transduction. The in vivo anti-tumour effect of cardamonin was assessed in a xenograft model.

RESULTS

Cardamonin disrupted mTOR complex interactions by decreasing Raptor protein levels. RagCT90N overexpression via lentiviral infection increased cell proliferation and mTORC1 activation. The viability and tumour growth rate of RagCT90N-mutant cells were more sensitive to cardamonin treatment than those of normal and RagCWT cells. Cardamonin also exhibited a stronger inhibitory effect on the phosphorylation of mTOR and p70 S6 kinase 1 in RagCT90N-mutant cells. Raptor knockdown abolishes the inhibitory effects of cardamonin on mTOR. An in vivo xenograft model demonstrated that the RagCT90N-mutant showed significantly higher sensitivity to cardamonin treatment.

CONCLUSIONS

Cardamonin exerts selective therapeutic effects on RagCT90N-mutant cells. Cardamonin can serve as a drug for individualised therapy for follicular lymphoma with RRAGC mutations.

Targeting Cell Signaling Pathways in Lung Cancer by Bioactive Phytocompounds

Lung cancer is a heterogeneous group of malignancies with high incidence worldwide. It is the most frequently occurring cancer in men and the second most common in women. Due to its frequent diagnosis and variable response to treatment, lung cancer was reported as the top cause of cancer-related deaths worldwide in 2020. Many aberrant signaling cascades are implicated in the pathogenesis of lung cancer, including those involved in apoptosis (B cell lymphoma protein, Bcl-2-associated X protein, first apoptosis signal ligand), growth inhibition (tumor suppressor protein or gene and serine/threonine kinase 11), and growth promotion (epidermal growth factor receptor/proto-oncogenes/phosphatidylinositol-3 kinase). Accordingly, these pathways and their signaling molecules have become promising targets for chemopreventive and chemotherapeutic agents. Recent research provides compelling evidence for the use of plant-based compounds, known collectively as phytochemicals, as anticancer agents. This review discusses major contributing signaling pathways involved in the pathophysiology of lung cancer, as well as currently available treatments and prospective drug candidates. The anticancer potential of naturally occurring bioactive compounds in the context of lung cancer is also discussed, with critical analysis of their mechanistic actions presented by preclinical and clinical studies.

Anticancer Potential of Natural Chalcones: In Vitro and In Vivo Evidence

There is no doubt that significant progress has been made in tumor therapy in the past decades. However, the discovery of new molecules with potential antitumor properties still remains one of the most significant challenges in the field of anticancer therapy. Nature, especially plants, is a rich source of phytochemicals with pleiotropic biological activities. Among a plethora of phytochemicals, chalcones, the bioprecursors of flavonoid and isoflavonoids synthesis in higher plants, have attracted attention due to the broad spectrum of biological activities with potential clinical applications. Regarding the antiproliferative and anticancer effects of chalcones, multiple mechanisms of action including cell cycle arrest, induction of different forms of cell death and modulation of various signaling pathways have been documented. This review summarizes current knowledge related to mechanisms of antiproliferative and anticancer effects of natural chalcones in different types of malignancies including breast cancers, cancers of the gastrointestinal tract, lung cancers, renal and bladder cancers, and melanoma.

Raptor couples mTORC1 and ERK1/2 inhibition by cardamonin with oxidative stress induction in ovarian cancer cells

Background

A balance on nutrient supply and redox homeostasis is required for cell survival, and increased antioxidant capacity of cancer cells may lead to chemotherapy failure.

Objective

To investigate the mechanism of anti-proliferation of cardamonin by inducing oxidative stress in ovarian cancer cells.

Methods

After 24 h of drug treatment, CCK8 kit and wound healing test were used to detect cell viability and migration ability, respectively, and the ROS levels were detected by flow cytometry. The differential protein expression after cardamonin administration was analyzed by proteomics, and the protein level was detected by Western blotting.

Results

Cardamonin inhibited the cell growth, which was related to ROS accumulation. Proteomic analysis suggested that MAPK pathway might be involved in cardamonin-induced oxidative stress. Western blotting showed that cardamonin decreased Raptor expression and the activity of mTORC1 and ERK1/2. Same results were observed in Raptor KO cells. Notably, in Raptor KO cells, the effect of cardamonin was weakened.

Conclusion

Raptor mediated the function of cardamonin on cellular redox homeostasis and cell proliferation through mTORC1 and ERK1/2 pathways.

Optochemical Control of mTOR Signaling and mTOR-Dependent Autophagy

As an important regulator of cell metabolism, proliferation, and survival, mTOR (mammalian target of rapamycin) signaling provides both a potential target for cancer treatment and a research tool for investigation of cell metabolism. One inhibitor for both mTORC1 and mTORC2 pathways, OSI-027, exhibited robust anticancer efficacy but induced side effects. Herein, we designed a photoactivatable OSI-027 prodrug, which allowed the release of OSI-027 after light irradiation to inhibit the mTOR signaling pathway, triggering autophagy and leading to cell death. This photoactivatable prodrug can provide novel strategies for mTOR-targeting cancer therapy and act as a new tool for investigating mTOR signaling and its related biological processes.

Novel Semi-Synthetic Cu (II)-Cardamonin Complex Exerts Potent Anticancer Activity against Triple-Negative Breast and Pancreatic Cancer Cells via Inhibition of the Akt Signaling Pathway

Cardamonin is a polyphenolic natural product that has been shown to possess cytotoxic activity against a variety of cancer cell lines. We previously reported the semi-synthesis of a novel Cu (II)–cardamonin complex (19) that demonstrated potent antitumour activity. In this study, we further investigated the bioactivity of 19 against MDA-MB-468 and PANC-1 cancer cells in an attempt to discover an effective treatment for triple-negative breast cancer (TNBC) and pancreatic cancer, respectively. Results revealed that 19 abolished the formation of MDA-MB-468 and PANC-1 colonies, exerted growth-inhibitory activity, and inhibited cancer cell migration. Further mechanistic studies showed that 19 induced DNA damage resulting in gap 2 (G2)/mitosis (M) phase arrest and microtubule network disruption. Moreover, 19 generated reactive oxygen species (ROS) that may contribute to induction of apoptosis, corroborated by activation of caspase-3/7, PARP cleavage, and downregulation of Mcl-1. Complex 19 also decreased the expression levels of p-Akt and p-4EBP1, which indicates that the compound exerts its activity, at least in part, via inhibition of Akt signalling. Furthermore, 19 decreased the expression of c-Myc in PANC-1 cells only, which suggests that it may exert its bioactivity via multiple mechanisms of action. These results demonstrate the potential of 19 as a therapeutic agent for TNBC and pancreatic cancer.

An overview of the potential anticancer properties of cardamonin

Cancer is one of the leading causes of mortality, contributing to 9.6 million deaths globally in 2018 alone. Although several cancer treatments exist, they are often associated with severe side effects and high toxicities, leaving room for significant advancements to be made in the field. In recent years, several phytochemicals from plants and natural bioresources have been extracted and tested against various human malignancies using both in vitro and in vivo preclinical model systems. Cardamonin, a chalcone extracted from the Alpinia species, is an example of a natural therapeutic agent that has anti-cancer and anti-inflammatory effects against human cancer cell lines, including breast, lung, colon, and gastric, in both in vitro culture systems as well as xenograft mouse models. Earlier, cardamonin was used as a natural medicine against stomach related issues, diarrhea, insulin resistance, nephroprotection against cisplatin treatment, vasorelaxant and antinociceptive. The compound is well-known to inhibit proliferation, migration, invasion, and induce apoptosis, through the involvement of Wnt/β-catenin, NF-κB, and PI3K/Akt pathways. The good biosafety and pharmacokinetic profiling of cardamonin satisfy it as an attractive molecule for the development of an anticancer agent. The present review has summarized the chemo-preventive ability of cardamonin as an anticancer agent against numerous human malignancies.

M, Giribabu N, Abdul Majid AMS, Eid EEM, Alshawsh MA. Cardamonin Exerts Antitumor Effect on Human Hepatocellular Carcinoma Xenografts in Athymic Nude Mice through Inhibiting NF-κβ Pathway

Cardamonin (CADMN) exerts an in vitro antiproliferative and apoptotic actions against human hepatocellular carcinoma cells (HepG2). This study aimed to investigate the in vivo anti-tumorigenic action of CADMN against human hepatocellular carcinoma xenografts in an athymic nude mice, as well as to study the molecular docking and safety profile of this compound. Acute toxicity study demonstrated that CADMN is safe and well-tolerated up to 2000 mg/kg in ICR mice. Oral administration of 50 mg/kg/day of CADMN in xenografted nude mice showed a significant suppression in tumor growth as compared to untreated control group without pronounced toxic signs. Immunohistochemistry assay showed downregulation of proliferative proteins such as PCNA and Ki-67 in treated groups as compared to untreated control. Additionally, immunofluorescence analysis showed a significant downregulation in anti-apoptotic Bcl-2 protein, whereas pre-apoptotic Bax protein was significantly upregulated in nude mice treated with 25 and 50 mg/kg CADMN as compared to untreated mice. The findings also exhibited down-regulation of NF-κB-p65, and Ikkβ proteins, indicating that CADMN deactivated NF-κB pathway. The molecular docking studies demonstrated that CADMN exhibits good docking performance and binding affinities with various apoptosis and proliferation targets in hepatocellular cancer cells. In conclusion, CADMN could be a potential anticancer candidate against hepatocellular carcinoma. Other pharmacokinetics and pharmacodynamics properties, however, need to be further investigated in depth.

Alpinetin delays high-fat diet-aggravated lung carcinogenesis

Alpinetin (ALP) has been reported to act as an anticancer agent. This study was carried out to elucidate the effect of ALP on high-fat diet (HFD)-induced aggressive cancer progression. C57BL/6 mice were fed with a control diet (CD) or HFD and administered with ALP. Following 6 weeks of feeding, mice were inoculated subcutaneously with Lewis lung carcinoma cells (LLC) to develop transplanted lung tumour. ALP suppressed cell proliferation which drives HFD-induced lung cancer progression. ALP inhibited lipid accumulation in tumour and tumour cells cultured in vitro. qPCR and ELISA analysis of tumour tissues revealed ALP restrained macrophages accumulation, M2s polarization and chemokine secretion. Further, in macrophages cultured in tumour cells conditioned medium (CM), ALP was confirmed to decrease M2s markers expression and chemokine production under high fat. These results demonstrate that ALP suppresses HFD-promoted harmful changes in tumour microenvironments which are crucial in curbing pulmonary tumour aggravation.

Possible Participation of Ionotropic Glutamate Receptors and l-Arginine-Nitric Oxide-Cyclic Guanosine Monophosphate-ATP-Sensitive K+ Channel Pathway in the Antinociceptive Activity of Cardamonin in Acute Pain Animal Models

The perception of pain caused by inflammation serves as a warning sign to avoid further injury. The generation and transmission of pain impulses involves various pathways and receptors. Cardamonin isolated from Boesenbergia rotunda (L.) Mansf. has been reported to exert antinociceptive effects in thermal and mechanical pain models; however, the precise mechanism has yet to be examined. The present study investigated the possible mechanisms involved in the antinociceptive activity of cardamonin on protein kinase C, N-methyl-d-aspartate (NMDA) and non-NMDA glutamate receptors, l-arginine/cyclic guanosine monophosphate (cGMP) mechanism, as well as the ATP-sensitive potassium (K⁺) channel. Cardamonin was administered to the animals intra-peritoneally. Present findings showed that cardamonin significantly inhibited pain elicited by intraplantar injection of phorbol 12-myristate 13-acetate (PMA, a protein kinase C activator) with calculated mean ED₅₀ of 2.0 mg/kg (0.9–4.5 mg/kg). The study presented that pre-treatment with MK-801 (NMDA receptor antagonist) and NBQX (non-NMDA receptor antagonist) significantly modulates the antinociceptive activity of cardamonin at 3 mg/kg when tested with glutamate-induced paw licking test. Pre-treatment with l-arginine (a nitric oxide precursor), ODQ (selective inhibitor of soluble guanylyl cyclase) and glibenclamide (ATP-sensitive K⁺ channel inhibitor) significantly enhanced the antinociception produced by cardamonin. In conclusion, the present findings showed that the antinociceptive activity of cardamonin might involve the modulation of PKC activity, NMDA and non-NMDA glutamate receptors, l-arginine/nitric oxide/cGMP pathway and ATP-sensitive K⁺ channel.

Cardamonin inhibits cell proliferation by caspase-mediated cleavage of Raptor

The antiproliferative effect of cardamonin on mTORC1 is related with downregulation of Raptor. We investigated the mechanism that cardamonin decreases Raptor expression through caspase-mediated protein degradation. SKOV3 cells and HeLa cells were pretreated with caspase inhibitor z-VAD-fmk for 30 min and then exposed to different doses of cardamonin and cisplatin, respectively. We analyzed the gene expression of caspases based on TCGA and GTEx gene expression data in serous cystadenocarcinoma and normal tissues, monitored caspase activity by caspase colorimetric assay kit, detected expression of mTORC1-associated proteins and apoptosis-associated proteins by western blotting, and finally detected cell viability by methyl thiazolyl tetrazolium (MTT) assay. A different expression of caspases except caspase-1 was found between serous cystadenocarcinoma and normal tissues. Raptor was cleaved when caspases were activated by cisplatin and caspase-6/caspase-8 was activated by cardamonin in SKOV3 cells. We further used a monoclonal antibody recognizing the N-terminal part of Raptor to find that Raptor was cleaved into a smaller fragment of about 70 kDa by cardamonin and was rescued by z-VAD-fmk treatment. As a result of Raptor cleavage, mTORC1 activity was decreased and cell viability was inhibited, while cell apoptosis was induced in SKOV3 cells. Notably, similar results are only observed in HeLa cells with a high dose of cardamonin. We concluded that caspase-mediated cleavage of Raptor might be an important mechanism in that cardamonin regulated Raptor and mTORC1 activity.

Cardamonin: A new player to fight cancer via multiple cancer signaling pathways

Nature's pharmacy has undoubtedly served humans as an affordable and safer health-care regime for a long times. Cardamonin, a chalconoid present in several plants has been known for a longtime to have beneficial properties towards human health. In this review, we aimed to highlight the recent advances achieved in discovering the pharmacological properties of cardamonin. Cardamonin is cardamom-derived chalcone, which plays a role in cancer treatment, immune system modulation, inflammation and pathogens killing. Through the modulation of cellular signaling pathways, cardamonin activates cell death signal to induce apoptosis in malignant cells that results in the inhibition of cancer development. Moreover, cardamonin arrests cell cycle by altering the expression of regulatory proteins during malignant cells division. Due to its relatively selective cytotoxic potential against host malignant cells, cardamonin is emerging as a promising novel experimental anticancer agent. The potential of cardamonin to target various signaling molecules, transcriptional factors, cytokines and enzymes, such as mTOR, NF-κB, Akt, STAT3, Wnt/β-catenin and COX-2 enhances the opportunity to explore it as a new multi-target therapeutic agent. The pharmacokinetic and biosafety profile of cardamonin favor it as a potentially safe biomolecule for pharmaceutical drug development.

Cardamonin induces immune responses and enhances survival rate in WEHI-3 cell-generated mouse leukemia in vivo

Cardamonin, a monomeric alkaloid, is isolated from Alpinia conchigera Griff and other natural plants. Recently, it has been focused on its anticancer activities, and no information showing its immune effects on leukemia mice was reported. In this study, we investigated the immune effects of cardamonin on WEHI-3 cell-generated leukemia mice. Forty BALB/c mice were randomly divided into four groups: Group I mice were normal animals and groups II-IV were leukemia. Group II mice, as a positive control, were administered with normal diet, and group III and IV mice were treated with 1 and 5 mg/kg of cardamonin, respectively, by intraperitoneal injection every 2 days for 14 days. The population of white blood cells, macrophage phagocytosis, and the proliferations of T and B cells were analyzed by flow cytometry. Another forty mice were also separated randomly into four groups for the determination of survival rate. Results showed that cardamonin did not affect body weight. Cardamonin decreased CD3, CD11b, and Mac-3 cell populations but increased CD19 number. Cardamonin enhanced phagocytic abilities of macrophages from the peripheral blood mononuclear cells of leukemia mice. Furthermore, cardamonin at 1 mg/kg treatment improved the survival rate of leukemia mice in vivo. Therefore, cardamonin could be applied for a leukemia therapeutic reagent at a defined dose.

Anti‑proliferative effect of cardamonin on mTOR inhibitor‑resistant cancer cells

A number of mammalian target of rapamycin (mTOR) inhibitors have been approved for the treatment of certain types of cancer or are currently undergoing clinical trials. However, mTOR targeted therapy exerts selective pressure on tumour cells, which leads to the preferential growth of resistant subpopulations. There are two classes of mTOR inhibitors: i) The rapalogs, such as rapamycin, which bind to the 12‑kDa FK506‑binding protein/rapamycin‑binding domain of mTOR; and ii) the ATP‑competitive inhibitors, such as AZD8055, which block the mTOR kinase domain. Cardamonin inhibits mTOR by decreasing the expression of regulatory‑associated protein of mTOR (Raptor), a mechanism of action which differs from the currently available mTOR inhibitors. The present study investigated the inhibitory effects of cardamonin on mTOR inhibitor‑resistant cancer cells. HeLa cervical cancer cells and MCF‑7 breast cancer cells were exposed to high concentrations of mTOR inhibitors, until resistant clones emerged. Cytotoxicity was measured using the MTT and colony forming assays. The inhibitory effect of cardamonin on mTOR signalling was assessed by western blotting. The resistant cells were less sensitive to mTOR inhibitors compared with the parental cells. Consistent with the anti‑proliferation effect, rapamycin and AZD8055 had no effect on the phosphorylation of rapamycin‑sensitive sites on ribosomal protein S6 kinase B1 (S6K1) and AZD8055‑sensitive sites on protein kinase B and eukaryotic translation initiation factor 4E binding protein 1 (Thr 37/46), respectively, in rapamycin‑ and AZD8055‑resistant cells. Cardamonin inhibited cell proliferation and decreased the phosphorylation of mTOR and S6K1, as well as the protein level of raptor, in the mTOR inhibitor‑resistant cells. Therefore, cardamonin may serve as a therapeutic agent for patients with cervical and breast cancer resistant to mTOR inhibitors.

Glycolysis inhibition via mTOR suppression is a key step in cardamonin-induced autophagy in SKOV3 cells

Background

Autophagy occurs in cells that undergoing nutrient deprivation. Glycolysis rapidly supplies energy for the proliferation of cancer cells. Cardamonin inhibits proliferation and enhances autophagy by mTORC1 suppression in ovarian cancer cells. Here, we investigate the relationship between cardamonin-triggered autophagy and glycolysis inhibition via mTORC1 suppression.

Methods

Treated with indicated compounds, ATP content and the activity of hexokinase (HK) and lactate dehydrogenase (LDH) were analyzed by the assay kits. Autophagy was detected by monodansylcadaverin (MDC) staining. The relationship between cardamonin-triggered autophagy and glycolysis inhibition via mTORC1 suppression was analyzed by Western blot.

Results

We found that cardamonin inhibited the lactate secretion, ATP production, and the activity of HK and LDH. The results demonstrated that cardamonin enhanced autophagy in SKOV3 cells, as indicated by acidic compartments accumulation, microtubule-associated protein 1 Light Chain 3-II (LC3-II) and lysosome associated membrane protein 1 up-regulation. Our results showed that the activation of mTORC1 signaling and the expression HK2 were reduced by cardamonin; whereas the phosphorylation of AMPK (AMP-activated protein kinase) was increased. We also confirmed that the AMPK inhibitor, Compound C, reversed cardamonin-induced upregulation of LC3-II.

Conclusion

These results suggest that cardamonin-induced autophagy is associated with inhibition on glycolysis by down-regulating the activity of mTORC1 in ovarian cancer cells.

Antinociceptive Effects of Cardamonin in Mice: Possible Involvement of TRPV₁, Glutamate, and Opioid Receptors

Pain is one of the most common cause for hospital visits. It plays an important role in inflammation and serves as a warning sign to avoid further injury. Analgesics are used to manage pain and provide comfort to patients. However, prolonged usage of pain treatments like opioids and NSAIDs are accompanied with undesirable side effects. Therefore, research to identify novel compounds that produce analgesia with lesser side effects are necessary. The present study investigated the antinociceptive potentials of a natural compound, cardamonin, isolated from Boesenbergia rotunda (L) Mansf. using chemical and thermal models of nociception. Our findings showed that intraperitoneal and oral administration of cardamonin (0.3, 1, 3, and 10 mg/kg) produced significant and dose-dependent inhibition of pain in abdominal writhing responses induced by acetic acid. The present study also demonstrated that cardamonin produced significant analgesia in formalin-, capsaicin-, and glutamate-induced paw licking tests. In the thermal-induced nociception model, cardamonin exhibited significant increase in response latency time of animals subjected to hot-plate thermal stimuli. The rota-rod assessment confirmed that the antinociceptive activities elicited by cardamonin was not related to muscle relaxant or sedative effects of the compound. In conclusion, the present findings showed that cardamonin exerted significant peripheral and central antinociception through chemical- and thermal-induced nociception in mice through the involvement of TRPV₁, glutamate, and opioid receptors.

Autophagy induced by cardamonin is associated with mTORC1 inhibition in SKOV3 cells

BACKGROUND

The mammalian target of rapamycin (mTOR) integrates energy level to modulate cell proliferation and autophagy. Cardamonin exhibits anti-proliferative activity through inhibiting mTOR. In this study, the effect of cardamonin on autophagy and its mechanism on mTOR inhibition were investigated.

METHODS

Cell viability and proliferation were measured by MTT assay and BrdU incorporation, respectively. Cell apoptosis was assayed by flow cytometry and cell autophagy was detected by electron microscopy and GFP-LC3 fluorescence. The mechanism of cardamonin on mTORC1 inhibition was investigated by Raptor siRNA and Raptor over-expression.

RESULTS

The cell viability and proliferation were inhibited by cardamonin. The autophagosomes and the protein level of LC3-II were increased by cardamonin. Cell apoptosis and the levels of cleaved PARP and Caspase-3 were increased by cardamonin. Cardamonin inhibited the phosphorylation of mTOR and ribosome S6 protein kinase 1 (S6K1) as well as the protein level of regulatory associated protein of mTOR (Raptor). However, cardamonin had no effect on the component of mTORC2 and its downstream substrate Akt. The inhibitory effect of cardamonin on the phosphorylation of mTOR and S6K1 was eliminated by Raptor knockdown with siRNA, whereas this effect of cardamonin was stronger than that of rapamycin and AZD8055 in Raptor over-expression cells. Cell viability was inhibited by cardamonin in both Raptor knockdown and Raptor over-expression cells, which was consistent with the inhibitory effect of cardamonin on mTOR.

CONCLUSION

These findings demonstrated that the autophagy induced by cardamonin was associated with mTORC1 inhibition through decreasing the protein level of Raptor in SKOV3 cells.

Raptor mediates the antiproliferation of cardamonin by mTORC1 inhibition in SKOV3 cells

Purpose

Cardamonin inhibits the proliferation of SKOV3 cells by suppressing the mammalian target of rapamycin complex 1 (mTORC1). However, the mechanism of cardamonin on mTORC1 inhibition has not been well demonstrated. The regulatory-associated protein of TOR (Raptor) is an essential component of mTORC1. Here, we investigated the role of Raptor in the mTORC1 inhibition effect of cardamonin in SKOV3 cells.

Methods

The expression of Raptor was knockdown by small interfering RNA (siRNA). The expressions of specific binding proteins of mTORC1 were analyzed by Western blotting, and the cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay.

Results

Rapamycin, AZD8055, and cardamonin inhibited the activity of mammalian target of rapamycin (mTOR). Different from rapamycin and AZD8055, cardamonin suppressed the phosphorylation and protein expression of Raptor. Transfected with Raptor siRNA, the mTOR activation and proliferation of SKOV3 cells were decreased, and these effects were strengthened by cardamonin in Raptor siRNA SKOV3 cells. Cardamonin interfered with the lysosomal colocalization of mTOR with lysosomal associated membrane protein 2 (LAMP2), which was also hindered by Raptor siRNA. Furthermore, cardamonin strengthened the inhibitory effect on the lysosomal localization of mTOR in Raptor siRNA cells.

Conclusion

Our results suggested that Raptor mainly mediated the inhibition of cardamonin on mTORC1 in SKOV3 cells.

Discovery of a highly active anticancer analogue of cardamonin that acts as an inducer of caspase-dependent apoptosis and modulator of the mTOR pathway

Cardamonin is a natural chalcone that has been shown to exhibit high anticancer activity. In an attempt to discover analogues of cardamonin with enhanced anticancer activity, 19 analogues were synthesized and tested against A549 and HK1 cell lines. Results of the MTS cell viability assay showed that several derivatives possessed cytotoxic activities that were several-fold more potent than cardamonin. SAR analysis showed the importance of the ketone and alkene groups for bioactivity, while substituting cardamonin's phenolic groups with more polar moieties resulted in activity enhancement. As part of the SAR study and further exploration of chemical space, the effect of metal coordination on cytotoxicity was also investigated, but it was only possible to successfully obtain the Cu (II) complex of cardamonin (19). Compound 19 was the most active analogue possessing IC₅₀ values of 13.2μM and 0.7μM against A549 and HK1 cells, corresponding to a 5- and 32-fold increase in activity, respectively. It was also able to significantly inhibit the migration of A549 and HK1 cells. Further mode of action studies have shown that the most active analogue, 19, induced DNA damage resulting in G2/M-phase cell- cycle arrest in both cell lines. These events further led to the induction of apoptosis by the compound via caspase-3/7 and caspase-9 activation, PARP cleavage and downregulation of Mcl-1 expression. Moreover, 19 inhibited the expression levels of p-mTOR and p-4EBP1, which indicated that it exerted its anticancer activity, at least in part, via inhibition of the mTOR signalling pathway.

Cardamonin enhances the anti-proliferative effect of cisplatin on ovarian cancer

The mammalian target of rapamycin (mTOR) is well-known as a promising therapeutic target in various cancer cells. mTOR activation decreases the sensitivity of ovarian cancer to cisplatin. Cardamonin inhibits the proliferation of various cancer cells by mTOR suppression. The present study examined whether cardamonin combined with cisplatin is efficacious for the anti-proliferation of ovarian cancer cells. The anti-proliferative effect was determined by MTT and cell cycle assays. Activation of the mTOR signal pathway and the expression of anti-apoptotic proteins were evaluated by western blot analysis. Cardamonin significantly enhanced the effects of cisplatin on cell proliferation and cell cycle progression. The expression of B cell lymphoma-2, X-linked inhibitor of apoptosis protein and Survivin was significantly decreased following combination treatment. Furthermore, the activation of mTOR and its downstream 70 kDa ribosomal protein S6 kinase was inhibited by cardamonin. These results demonstrated that the combinatorial effects of cardamonin and cisplatin on anti-proliferation were enhanced by suppressing the expression of anti-apoptotic proteins and activation of mTOR in ovarian cancer cells.

Cardamonin inhibits colonic neoplasia through modulation of MicroRNA expression

Colorectal cancer is currently the third leading cause of cancer related deaths. There is considerable interest in using dietary intervention strategies to prevent chronic diseases including cancer. Cardamonin is a spice derived nutraceutical and herein, for the first time we evaluated the therapeutic benefits of cardamonin in Azoxymethane (AOM) induced mouse model of colorectal cancer. Mice were divided into 4 groups of which three groups were given six weekly injections of AOM. One group served as untreated control and remaining groups were treated with either vehicle or Cardamonin starting from the same day or 16 weeks after the first AOM injection. Cardamonin treatment inhibited the tumor incidence, tumor multiplicity, Ki-67 and β-catenin positive cells. The activation of NF-kB signaling was also abrogated after cardamonin treatment. To elucidate the mechanism of action a global microRNA profiling of colon samples was performed. Computational analysis revealed that there is a differential expression of miRNAs between these groups. Subsequently, we extend our findings to human colorectal cancer and found that cardamonin inhibited the growth, induces cell cycle arrest and apoptosis in human colorectal cancer cell lines. Taken together, our study provides a better understanding of chemopreventive potential of cardamonin in colorectal cancer.

Cardamonin induces ROS-mediated G2/M phase arrest and apoptosis through inhibition of NF-κB pathway in nasopharyngeal carcinoma

Cardamonin has been demonstrated to have an inhibitory effect in many cancers, but its underlying mechanism remains elusive. Here, we studied, for the first time, the mechanism of cardamonin-induced nasopharyngeal carcinoma cell death both in vitro and in vivo. In our study, we showed that cardamonin inhibited cancer cell growth by inducing G2/M phase cell cycle arrest and apoptosis via accumulation of ROS. NF-κB activation was involved in breaking cellular redox homeostasis. Therefore, our results provided new insight into the mechanism of the antitumor effect of cardamonin, supporting cardamonin as a prospective therapeutic drug in nasopharyngeal carcinoma by modulating intracellular redox balance.

Cardamonin, a chalcone, inhibits human triple negative breast cancer cell invasiveness by downregulation of Wnt/β-catenin signaling cascades and reversal of epithelial-mesenchymal transition

Cardamonin (CD), an active chalconoid, has shown potent anticancer effects in preclinical studies; however, the effect and underlying mechanism of CD for the treatment of triple negative breast cancer (TNBC) is unclear. This study aims to examine the cytotoxic effects of CD and investigate the underlying mechanism in human TNBC cells. The results show that CD exhibits cytotoxicity by inducing apoptosis and cell cycle arrest in TNBC cells via modulation of Bcl-2, Bax, cyt-C, cleaved caspase-3, and PARP. We find that CD significantly increases expression of the epithelial marker E-cadherin, while reciprocally decreasing expression of mesenchymal markers such as snail, slug, and vimentin in BT-549 cells. In parallel with epithelial-mesenchymal transition (EMT) reversal, CD down regulates invasion and migration of BT-549 cells. CD markedly reduces stability and nuclear translocation of β-catenin, accompanied with downregulation of β-catenin target genes. Using the TopFlash luciferase reporter assay, we reveal CD as a specific inhibitor of the Wnt3a-induced signaling. These results suggest the involvement of the Wnt/β-catenin signaling in the CD-induced EMT reversion of BT-549 cells. Notably, CD restores the glycogen synthase kinase-3β (GSK3β) activity, required for β-catenin destruction via the proteasome-mediated system, by inhibiting the phosphorylation of GSK3β by Akt. These occurrences ultimately lead to the blockage of EMT and the invasion of TNBC cells. Further antitumor activity of CD was tested in 4T1 (TNBC cells) induced tumor and it was found that CD significantly inhibited the tumor volume at dose of 5 mg/kg-treated mice. © 2016 BioFactors, 43(2):152-169, 2017.

Cardamonin induces apoptosis by suppressing STAT3 signaling pathway in glioblastoma stem cells

Glioblastoma stem cells (GSCs) are the initiating cells in glioblastoma multiforme (GBM) and contribute to the resistance of GBM to chemotherapy and radiation. In the present study, we investigated the effects of cardamonin (3,4,2,4-tetrahydroxychalcone) on the self-renewal and apoptosis of GSCs, and if its action is associated with signal transducer and activator of transcription 3 (STAT3) pathway. CD133(+) GSCs, a kind of GSCs line, was established from human glioblastoma tissues. Cardamonin inhibited the proliferation and induced apoptosis in CD133+ GSCs. The proapoptotic effects of temozolomide (TMZ) were further enhanced by cardamonin in CD133+ GSCs and U87 cells in vitro. For in vivo study, injection of 5 × 10(5) cells of CD133+ GSCs subcutaneously (s.c.) into nude mice, 100 % of large tumors were developed within 8 weeks in all mice; in contrast, only one out of five mice developed a small tumor when 5 × 10(5) cells of CD133(-) GMBs cells were injected. Cardamonin also inhibited STAT3 activation by luciferase assay and suppressed the expression of the downstream genes of STAT3, such as Bcl-XL, Bcl-2, Mcl-1, survivin, and VEGF. Furthermore, cardamonin locked nuclear translocation and dimerization of STAT3 in CD133(+) GSCs. Docking analysis confirmed that cardamonin molecule was successfully docked into the active sites of STAT3 with a highly favorable binding energy of -10.78 kcal/mol. The study provides evidence that cardamonin is a novel inhibitor of STAT3 and has the potential to be developed as a new anticancer agent targeting GSCs. This study also reveals that targeting STAT3 signal pathway is an important strategy for the treatment of human GBM.

Cardamonin Inhibits Metastasis of Lewis Lung Carcinoma Cells by Decreasing mTOR Activity

The mammalian target of rapamycin (mTOR) regulates the motility and invasion of cancer cells. Cardamonin is a chalcone that exhibits anti-tumor activity. The previous study had proved that the anti-tumor effect of cardamonin was associated with mTOR inhibition. In the present study, the anti-metastatic effect of cardamonin and its underlying molecule mechanisms were investigated on the highly metastatic Lewis lung carcinoma (LLC) cells. The proliferation, invasion and migration of LLC cells were measured by MTT, transwell and wound healing assays, respectively. The expression and activation of mTOR- and adhesion-related proteins were assessed by Western blotting. The in vivo effect of cardamonin on the metastasis of the LLC cells was investigated by a mouse model. Treated with cardamonin, the proliferation, invasion and migration of LLC cells were significantly inhibited. The expression of Snail was decreased by cardamonin, while that of E-cadherin was increased. In addition, cardamonin inhibited the activation of mTOR and its downstream target ribosomal S6 kinase 1 (S6K1). Furthermore, the tumor growth and its lung metastasis were inhibited by cardamonin in C57BL/6 mice. It indicated that cardamonin inhibited the invasion and metastasis of LLC cells through inhibiting mTOR. The metastasis inhibitory effect of cardamonin was correlated with down-regulation of Snail and up-regulation of E-cadherin.

Cardamonin induces autophagy and an antiproliferative effect through JNK activation in human colorectal carcinoma HCT116 cells

Cardamonin (2',4'-dihydroxy-6'-methoxychalcone) is derived from Alpinia katsumadai Hayata (Zingiberaceae), a plant that has been used in Traditional Chinese Medicine for thousands of years. Several anticancer agents have been reported to induce autophagy, which either protects cells or further sensitizes cells to drug treatment. However, the possible autophagic and antiproliferative effects of cardamonin on the human colorectal carcinoma HCT116 cell line are unclear. In the present study, experiments were conducted to determine the effects of cardamonin on cell proliferation, cell cycle distribution, and stimulation of autophagy in cultures of the HCT116 cell line. The results showed that cardamonin inhibited cell proliferation, induced G2/M phase cell cycle arrest, and enhanced autophagy in HCT116 cells. We found evidence that cardamonin-induced autophagic and antiproliferative effects are regulated by the tumor protein p53. We also found that the enhanced activation of c-Jun N-terminal kinase (JNK) by cardamonin was partially regulated by p53 and was critical for cardamonin-induced autophagic and antiproliferative effects in HCT116 cells. These findings suggest that cardamonin or other anticancer agents that increase p53/JNK-dependent stimulation of autophagy could be used to effectively treat patients with colorectal carcinoma.

Cardamonin Suppresses TGF-β1-Induced Epithelial Mesenchymal Transition via Restoring Protein Phosphatase 2A Expression

Epithelial mesenchymal transition (EMT) is the first step in metastasis and implicated in the phenotype of cancer stem cells. Therefore, understanding and controlling EMT, are essential to the prevention and cure of metastasis. In the present study, we examined, by Western blot, reverse transcription polymerase chain reaction (RT-PCR), and confocal microscopy, the effects of cardamonin (CDN) on transforming growth factor-β1 (TGF-β1)-induced EMT of A549 lung adenocarcinoma cell lines. TGF-β1 induced expression of N-cadherin and decreased expression of E-cadherin. CDN suppressed N-cadherin expression and restored E-cadherin expression. Further, TGF-β1 induced migration and invasion of A549 cancer cells, which was suppressed by CDN. TGF-β1 induced c-Jun N-terminal kinase (JNK) activation during EMT, but CDN blocked it. Protein serine/threonine phosphatase 2A (PP2A) expression in A549 cancer cells was reduced by TGF-β1 but CDN restored it. The overall data suggested that CDN suppresses TGF-β1-induced EMT via PP2A restoration, making it a potential new drug candidate that controls metastasis.