Sanggenon C decreases tumor cell viability associated with proteasome inhibition

Gastrointestinal Cancer Therapeutics via Triggering Unfolded Protein Response and Endoplasmic Reticulum Stress by 2-Arylbenzofuran

Gastrointestinal cancers are a major global health challenge, with high mortality rates. This study investigated the anti-cancer activities of 30 monomers extracted from Morus alba L. (mulberry) against gastrointestinal cancers. Toxicological assessments revealed that most of the compounds, particularly immunotoxicity, exhibit some level of toxicity, but it is generally not life-threatening under normal conditions. Among these components, Sanggenol L, Sanggenon C, Kuwanon H, 3'-Geranyl-3-prenyl-5,7,2',4'-tetrahydroxyflavone, Morusinol, Mulberrin, Moracin P, Kuwanon E, and Kuwanon A demonstrate significant anti-cancer properties against various gastrointestinal cancers, including colon, pancreatic, and gastric cancers. The anti-cancer mechanism of these chemical components was explored in gastric cancer cells, revealing that they inhibit cell cycle and DNA replication-related gene expression, leading to the effective suppression of tumor cell growth. Additionally, they induced unfolded protein response (UPR) and endoplasmic reticulum (ER) stress, potentially resulting in DNA damage, autophagy, and cell death. Moracin P, an active monomer characterized as a 2-arylbenzofuran, was found to induce ER stress and promote apoptosis in gastric cancer cells, confirming its potential to inhibit tumor cell growth in vitro and in vivo. These findings highlight the therapeutic potential of Morus alba L. monomers in gastrointestinal cancers, especially focusing on Moracin P as a potent inducer of ER stress and apoptosis.

Cortex Mori extracts induce apoptosis and inhibit tumor invasion via blockage of the PI3K/AKT signaling in melanoma cells

Melanoma, the most aggressive and deadliest form of skin cancer, has attracted increased attention due to its increasing incidence worldwide. The Cortex Mori (CM) has long been used as a classical traditional Chinese medicine (TCM) to treat various diseases, including cancer. The bioactive components and underlying mechanisms, however, remain largely unknown. The current study aims to investigate the anti-melanoma effects of CM and potential mechanisms through combined network pharmacology and bioinformatic analyses, and validated by in vitro and in vivo experiments. We report here that CM has anti-melanoma activity both in vitro and in vivo. Furthermore, 25 bioactive compounds in CM were found to share 142 melanoma targets, and network pharmacology and enrichment analyses suggested that CM inhibits melanoma through multiple biological processes and signaling pathways, particularly the PI3K-AKT signaling inhibition and activation of apoptotic pathways, which were further confirmed by biochemical and histological examinations. Finally, partial CM-derived bioactive compounds were found to show anti-melanoma effects, validating the anti-melanoma potential of bioactive ingredients of CM. Taken together, these results reveal bioactive components and mechanisms of CM in inhibiting melanoma, providing them as potential anti-cancer natural products for the treatment of melanoma.

Sanggenon C Ameliorates Cerebral Ischemia-Reperfusion Injury by Inhibiting Inflammation and Oxidative Stress through Regulating RhoA-ROCK Signaling

Sanggenon C (SC), a natural flavonoid extracted from Cortex Mori (Sang Bai Pi), is reported to possess anti-inflammatory and antioxidant properties in hypoxia. The present study aimed to investigate the therapeutic potential and the underlying mechanisms of SC in cerebral ischemia-reperfusion (I/R) injury. A rat model of reversible middle cerebral artery occlusion (MCAO) was used to induce cerebral I/R injury in vivo, and SC was administrated intragastrically. Brain injuries were evaluated using Bederson scores, brain water content, and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. The levels of inflammatory factors and oxidative stress were examined using corresponding kits. Cell apoptosis was evaluated by TUNEL. Moreover, the expressions of apoptosis-related and RhoA/ROCK signaling-related proteins were detected through western blotting. In vitro, RhoA was overexpressed in oxygen-glucose deprivation and reperfusion (OGD/R)-induced PC12 cells to confirm the contribution of RhoA-ROCK signaling inhibition by SC to the neuroprotective effects post OGD/R. Pretreatment with SC significantly ameliorated the neurologic impairment, brain edema, and cerebral infarction post MCAO-reperfusion, associated with reductions of inflammation, oxidative stress, and cell apoptosis in the brain. Furthermore, SC remarkably downregulated the expression of RhoA/ROCK signaling-related proteins post MCAO-reperfusion in rats, while overexpression of RhoA reversed the beneficial effects of SC on protecting against inflammation and oxidative stress in OGD/R-induced PC12 cells. Taken together, these findings demonstrated that SC exerts neuroprotective effects after cerebral I/R injury via inhibiting inflammation and oxidative stress through regulating RhoA-ROCK signaling, suggesting a therapeutic potential of SC in cerebral I/R injury.

Natural product scaffolds as inspiration for the design and synthesis of 20S human proteasome inhibitors

The 20S proteasome is a valuable target for the treatment of a number of diseases including cancer, neurodegenerative disease, and parasitic infection. In an effort to discover novel inhibitors of the 20S proteasome, many reseaarchers have looked to natural products as potential leads for drug discovery. The following review discusses the efforts made in the field to isolate and identify natural products as inhibitors of the proteasome. In addition, we describe some of the modifications made to natural products in order to discover more potent and selective inhibitors for potential disease treatment.

Steric Effect of Antioxidant Diels-Alder-Type Adducts: A Comparison of Sanggenon C with Sanggenon D

Sanggenons C and D are two Diels-Alder-type adducts from Chinese crude drug Sang-bai-pi. Structurally, both sanggenons construct stereoisomers. In the study, they were comparatively determined using four antioxidant assays, including ferric ion reducing antioxidant power (FRAP) assay, Cu²⁺-reducing assay, 1,1-diphenyl-2-picryl-hydrazl (DPPH•)-scavenging assay, and 2,2′-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid radical (ABTS•⁺)-scavenging assay. Their Fe²⁺-binding reactions were explored using UV-Vis spectra. Finally, their cytoprotective effects were evaluated using flow cytometry. In electron transfer (ET)-based FRAP and Cu²⁺-reducing assays, sanggenon D was found to have lower IC₅₀ values than sanggenon C; however, in multi-pathway-based DPPH•-scavenging and ABTS•⁺-scavenging assays, sanggenon C possessed lower IC₅₀ values than sanggenon D. UV-Vis spectra suggested that sanggenon C generated a bathochromic-shift (286 nm → 302 nm) and displayed stronger UV absorption than sanggenon D. In flow cytometry, sanggenon C and sanggenon D, respectively, exhibited 31.1% and 42.0% early apoptosis-percentages towards oxidative-stressed mesenchymal stem cells (MSCs). In conclusion, both sanggenons may undergo multiple pathways (e.g., ET and Fe²⁺-binding) to protect MSCs against oxidative stress. In the mere ET aspect, sanggenon D possesses a higher level than sanggenon C, while in multi-pathway-based radical-scavenging, Fe²⁺-binding, and cytoprotection aspects, sanggenon C is more active than sanggenon D. These discrepancies can conclusively be attributed to the steric effect.

Sanggenon C Stimulates Osteoblastic Proliferation and Differentiation, Inhibits Osteoclastic Resorption, and Ameliorates Prednisone-Induced Osteoporosis in Zebrafish Model

Sanggenon C (SC), which is a natural flavonoid found in the stem bark of Cortex Mori, has been discovered to have the antioxidant, anti-inflammatory, and antitumor properties. However, its effect in osteoporosis has not yet been reported. In this research, the effect of SC on the proliferation of MC3T3-E1 cells was evaluated by using the MTT assay. Alkaline phosphatase (ALP) activity and the mRNA expression of Runx2, Collagen I, OPG, and RANKL were examined. TRAP-positive cell counting and bone resorption pits were adopted to observe the effect of SC on the formation and function of osteoclasts. Next, the mRNA level of TRAP, CTSK, NFATc1, and TRAF6 of osteoclasts were measured by real-time qPCR. In addition, the anti-osteoporosis activity of SC in vivo was evaluated in the zebrafish model. Our study indicated that SC exhibited a significant stimulatory effect on MC3T3-E1 cell proliferation at 1 to 10 μM and caused an increase in ALP activity at 0.3 to 10 μM. It could upregulate the expression of Runx2, Collagen I, and increases the OPG/RANKL ratio. Furthermore, SC was found to inhibit the formation and function of osteoclasts, which is demonstrated by a lower number of TRAP-positive multinuclear cells and a fewer area of bone resorption pits compared to the control group. TRAP, CTSK, and NFATc1 were downregulated in 0.3 to 10 μM SC treated groups. In addition, 3 to 10 μM SC also inhibited the expression of TRAF6 mRNA. When prednisone-induced zebrafish was treated with 0.3, 1, 3, and 10 μM SC, higher mineralization of vertebrate column was discovered in a dose-dependent pattern, which suggests that SC could reverse the bone loss of zebrafish caused by prednisone. In summary, these findings indicated that SC has the potential to prevent or treat osteoporosis.

Sanggenon C protects against cardiomyocyte hypoxia injury by increasing autophagy

Sanggenon C is isolated from Morus alba, a plant that has been used for anti-inflammatory purposes in Oriental medicine. Little is known about the effect of Sanggenon C on cardiomyocyte hypoxia injury. This study, using H9c2 rat cardiomyoblasts, was designed to determine the effects of Sanggenon C on cardiomyocyte hypoxia injury. Inflammatory cytokine levels were measured by reverse transcription-polymerase chain reaction, reactive oxygen species were measured by 2′,7′-dichlorofluorescin diacetate fluorescent probe, autophagy was detected using the LC3II/I ratio and cell apoptosis was detected by TUNEL staining. The molecular mechanisms underlying Sanggenon C-induced cyto-protection were also determined by western blotting, especially the possible involvement of autophagy and AMP-activated protein kinase (AMPK). Results indicated that samples pretreated with different concentrations of Sanggenon C (1, 10 and 100 µM) reduced the expression levels of pro-inflammatory cytokines, including tumor necrosis factor α, interleukin (IL)-1 and IL-6, under hypoxia. The beneficial effects of Sanggenon C were also associated with reduced levels of reactive oxygen species generation and increased levels of antioxidant nitric oxide and superoxide dismutase. Sanggenon C enhanced hypoxia-induced autophagy as evidenced by the increased expression levels of autophagy-associated proteins Beclin and autophagy related 5 as well as the decreased the accumulation of p62, and increased the LC3II/I ratio. Sanggenon C also reduced hypoxia-induced apoptosis as detected by TUNEL staining and the expression of Bcl-2 proteins. The beneficial effects of Sanggenon C were associated with enhanced activation level of AMPKα and suppressed hypoxia-induced mechanistic target of rapamycin (mTOR) and forkhead box O3a (FOXO3a) phosphorylation. The AMPK inhibitor Compound C (CpC) was used, and the anti-apoptotic and pro-autophagy effects of Sanggenon C in response to hypoxia were abolished by CpC. In conclusion, the current study demonstrated that Sanggenon C possessed direct cytoprotective effects against hypoxia injury in cardiac cells via signaling mechanisms involving the activation of AMPK and concomitant inhibition of mTOR and FOXO3a.

[Sanggenon C induces apoptosis of prostate cancer PC3 cells by activating caspase 3 and caspase 9 pathways]

OBJECTIVE

To investigate the effects of Sanggenon C in inducing apoptosis of prostate cancer PC3 cell line and explore the underlying mechanism.

METHODS

The proliferation of PC3 cells treated for 24 h with 1, 5, 20, 50, and 100 µmol/L sanggenon C or treated with 20 µmol/L Sanggenon C for 0, 6, 12, 24 and 48 h was evaluated using MTT assay. Flow cytometry was performed for analysis of apoptosis of PC3 cells after exposure to sanggenon C with different treatment protocols, and the activity of caspase 3 was detected using spectrofluorometry. The inhibitory effect of sanggenon C on PC3 cells pretreated with DMSO, z-DEVD-fmk, z-LEHD-fmk or z-IETD-fmk for 1 h was detected by MTT assay.

RESULTS

Sanggenon C inhibited the proliferation of PC3 cells in a dose- and time-dependent manner (P<0.05 except for 1 µmol/L group) with a 24-h IC₅₀ of 18.76 µmol/L. Sanggenon C at 20 µmol/L caused inhibition rates of PC3 cells of 10.57%, 27.09%, 51.88%, 80.73% and 87.99% after treatment for 6, 12, 24, 48, and 72 h, respectively (P<0.05), and resulted in apoptosis rates of 7.43%, 20.91% and 37.56% at 12 h, 24 h and 48 h, respectively. Sanggenon C significantly increased caspase-3 activity in the cells, and its effect on PC3 cell proliferation was partially reversed by caspase 3 and caspase 9 inhibitors.

CONCLUSION

Sanggenon C can dose-dependently induce growth inhibition and apoptosis of PC3 cells possibly by activating caspase 9 and caspase 3 pathways.

[Sanggenon C induces apoptosis of prostate cancer PC3 cells by activating caspase 3 and caspase 9 pathways]

OBJECTIVE

To investigate the effects of Sanggenon C in inducing apoptosis of prostate cancer PC3 cell line and explore the underlying mechanism.

METHODS

The proliferation of PC3 cells treated for 24 h with 1, 5, 20, 50, and 100 µmol/L sanggenon C or treated with 20 µmol/L Sanggenon C for 0, 6, 12, 24 and 48 h was evaluated using MTT assay. Flow cytometry was performed for analysis of apoptosis of PC3 cells after exposure to sanggenon C with different treatment protocols, and the activity of caspase 3 was detected using spectrofluorometry. The inhibitory effect of sanggenon C on PC3 cells pretreated with DMSO, z-DEVD-fmk, z-LEHD-fmk or z-IETD-fmk for 1 h was detected by MTT assay.

RESULTS

Sanggenon C inhibited the proliferation of PC3 cells in a dose- and time-dependent manner (P<0.05 except for 1 µmol/L group) with a 24-h IC50 of 18.76 µmol/L. Sanggenon C at 20 µmol/L caused inhibition rates of PC3 cells of 10.57%, 27.09%, 51.88%, 80.73% and 87.99% after treatment for 6, 12, 24, 48, and 72 h, respectively (P<0.05), and resulted in apoptosis rates of 7.43%, 20.91% and 37.56% at 12 h, 24 h and 48 h, respectively. Sanggenon C significantly increased caspase-3 activity in the cells, and its effect on PC3 cell proliferation was partially reversed by caspase 3 and caspase 9 inhibitors.

CONCLUSION

Sanggenon C can dose-dependently induce growth inhibition and apoptosis of PC3 cells possibly by activating caspase 9 and caspase 3 pathways.

Sanggenon C induces apoptosis of colon cancer cells via inhibition of NO production, iNOS expression and ROS activation of the mitochondrial pathway

Sanggenon C is a well-known, major active agent of the flavonoid derivative of benzopyrone with valuable biological properties, including anticancer, anti-inflammatory, antimicrobial, antiviral, antithrombotic, and immune-modulatory activities. In this study, we investigated the molecular mechanisms by which sanggenon C mediated the induction of cell death in colorectal cancer cells (CRC). Treatment of colorectal cancer cells (LoVo, HT-29 and SW480) with sanggenon C (0, 5, 10, 20, 40 and 80 µM) resulted in inhibited proliferation of colon cancer cells. In addition, Sanggenon C (10, 20, 40 µM) induces apoptosis of HT-29 colon cancer cells as well as the increased ROS generation. Furthermore, treatment with sanggenon C increased the level of intracellular Ca²⁺ and ATP, while inhibited the nitric oxide production via inhibiting inducible nitric oxide synthase expression. This resulted in the activation of mitochondrial apoptosis pathway as evidenced by the decrease in Bcl-2 protein expression. Consistently, the anti-growth and pro-apoptosis effects of sanggenon C on xenograft colon tumor were further confirmed in vivo. Collectively, our results demonstrated sanggenon C induced apoptosis of colon cancer cells by increased reactive oxygen species generation and decreased nitric oxide production, which is associated with inhibition of inducible nitric oxide synthase expression and activation of mitochondrial apoptosis pathway.

Sanggenon C protects against pressure overload‑induced cardiac hypertrophy via the calcineurin/NFAT2 pathway

The effects of Sanggenon C on oxidative stress and inflammation have previously been reported; however, little is currently known regarding the effects of Sanggenon C on cardiac hypertrophy and fibrosis. In the present study, aortic banding (AB) was performed on mice to induce cardiac hypertrophy. After 1 week AB surgery, mice were treated daily with 10 or 20 mg/kg Sanggenon C for 3 weeks. Subsequently, cardiac function was detected using echocardiography and catheter-based measurements of hemodynamic parameters. In addition, the extent of cardiac hypertrophy was evaluated by pathological staining and molecular analysis of heart tissue in each group. After 4 weeks of AB, vehicle-treated mice exhibited cardiac hypertrophy, fibrosis, and deteriorated systolic and diastolic function, whereas treatment with 10 and 20 mg/kg Sanggenon C treatment ameliorated these alterations, as evidenced by attenuated cardiac hypertrophy and fibrosis, and preserved cardiac function. Furthermore, AB-induced activation of calcineurin and nuclear factor of activated T cells 2 (NFAT2) was reduced following Sanggenon C treatment. These results suggest that Sanggenon C may exert protective effects against cardiac hypertrophy and fibrosis via suppression of the calcineurin/NFAT2 pathway.

Established Human Cell Lines as Models to Study Anti-leukemic Effects of Flavonoids

Despite the extensive work on pathological mechanisms and some recent advances in the treatment of different hematological malignancies, leukemia continues to present a significant challenge being frequently considered as incurable disease. Therefore, the development of novel therapeutic agents with high efficacy and low toxicity is urgently needed to improve the overall survival rate of patients. In this comprehensive review article, the current knowledge about the anticancer activities of flavonoids as plant secondary polyphenolic metabolites in the most commonly used human established leukemia cell lines (HL-60, NB4, KG1a, U937, THP-1, K562, Jurkat, CCRF- CEM, MOLT-3, and MOLT-4) is compiled, revealing clear anti-proliferative, pro-apoptotic, cell cycle arresting, and differentiation inducing effects for certain compounds. Considering the low toxicity of these substances in normal blood cells, the presented data show a great potential of flavonoids to be developed into novel anti-leukemia agents applicable also in the malignant cells resistant to the current conventional chemotherapeutic drugs.

Inhibition of 19S proteasome-associated deubiquitinases by metal-containing compounds

Copper and gold complexes have clinical activity in several diseases including cancer. Recently, we have reported that the anti-cancer activity of copper (II) pyrithione CuPT and gold (I) complex auranofin is associated with targeting the 19S proteasome-associated deubiquitinases (DUBs), UCHL5 and USP14. Here we discuss metal DUB inhibitors in treating cancer and other diseases. (from Editor). Several copper and gold complexes have clinical activity in treating some human diseases including cancer. Recently, we have reported that the anti-cancer activity of copper (II) pyrithione CuPT and gold (I) complex auranofin is tightly associated with their ability to target and inhibit the 19S proteasome-associated deubiquitinases (DUBs), UCHL5 and USP14. In this article we review small molecule inhibitors of DUBs and 19S proteasome-associated DUBs. We then describe and discuss the ubique nature of CuPT and auranofin, which is inhibition of 19S proteasome-associated UCHL5 and USP14. We finally suggest the potential to develop novel, specific metal-based DUB inhibitors for treating cancer and other diseases.

Therapeutic targeting of cancer cell cycle using proteasome inhibitors

Proteasomes are multicatalytic protease complexes in the cell, involved in the non-lysosomal recycling of intra-cellular proteins. Proteasomes play a critical role in regulation of cell division in both normal as well as cancer cells. In cancer cells this homeostatic function is deregulated leading to the hyperactivation of the proteasomes. Proteasome inhibitors (PIs) are a class of compounds, which either reversibly or irreversibly block the activity of proteasomes and induce cancer cell death. Interference of PIs with the ubiquitin proteasome pathway (UPP) involved in protein turnover in the cell leads to the accumulation of proteins engaged in cell cycle progression, which ultimately put a halt to cancer cell division and induce apoptosis. Upregulation of many tumor suppressor proteins involved in cell cycle arrest are known to play a role in PI induced cell cycle arrest in a variety of cancer cells. Although many PIs target the proteasomes, not all of them are effective in cancer therapy. Some cancers develop resistance against proteasome inhibition by possibly activating compensatory signaling pathways. However, the details of the activation of these pathways and their contribution to resistance to PI therapy remain obscure. Delineation of these pathways may help in checking resistance against PIs and deducing effective combinational approaches for improved treatment strategies. This review will discuss some of the signaling pathways related to proteasome inhibition and cell division that may help explain the basis of resistance of some cancers to proteasome inhibitors and underline the need for usage of PIs in combination with traditional chemotherapy.

HDAC inhibitor L-carnitine and proteasome inhibitor bortezomib synergistically exert anti-tumor activity in vitro and in vivo

Combinations of proteasome inhibitors and histone deacetylases (HDAC) inhibitors appear to be the most potent to produce synergistic cytotoxicity in preclinical trials. We have recently confirmed that L-carnitine (LC) is an endogenous HDAC inhibitor. In the current study, the anti-tumor effect of LC plus proteasome inhibitor bortezomib (velcade, Vel) was investigated both in cultured hepatoma cancer cells and in Balb/c mice bearing HepG2 tumor. Cell death and cell viability were assayed by flow cytometry and MTS, respectively. Gene, mRNA expression and protein levels were detected by gene microarray, quantitative real-time PCR and Western blot, respectively. The effect of Vel on the acetylation of histone H3 associated with the p21(cip1) gene promoter was examined by using ChIP assay and proteasome peptidase activity was detected by cell-based chymotrypsin-like (CT-like) activity assay. Here we report that (i) the combination of LC and Vel synergistically induces cytotoxicity in vitro; (ii) the combination also synergistically inhibits tumor growth in vivo; (iii) two major pathways are involved in the synergistical effects of the combinational treatment: increased p21(cip1) expression and histone acetylation in vitro and in vivo and enhanced Vel-induced proteasome inhibition by LC. The synergistic effect of LC and Vel in cancer therapy should have great potential in the future clinical trials.

L-carnitine is an endogenous HDAC inhibitor selectively inhibiting cancer cell growth in vivo and in vitro

L-carnitine (LC) is generally believed to transport long-chain acyl groups from fatty acids into the mitochondrial matrix for ATP generation via the citric acid cycle. Based on Warburg's theory that most cancer cells mainly depend on glycolysis for ATP generation, we hypothesize that, LC treatment would lead to disturbance of cellular metabolism and cytotoxicity in cancer cells. In this study, Human hepatoma HepG2, SMMC-7721 cell lines, primary cultured thymocytes and mice bearing HepG2 tumor were used. ATP content was detected by HPLC assay. Cell cycle, cell death and cell viability were assayed by flow cytometry and MTS respectively. Gene, mRNA expression and protein level were detected by gene microarray, Real-time PCR and Western blot respectively. HDAC activities and histone acetylation were detected both in test tube and in cultured cells. A molecular docking study was carried out with CDOCKER protocol of Discovery Studio 2.0 to predict the molecular interaction between L-carnitine and HDAC. Here we found that (1) LC treatment selectively inhibited cancer cell growth in vivo and in vitro; (2) LC treatment selectively induces the expression of p21(cip1) gene, mRNA and protein in cancer cells but not p27(kip1); (4) LC increases histone acetylation and induces accumulation of acetylated histones both in normal thymocytes and cancer cells; (5) LC directly inhibits HDAC I/II activities via binding to the active sites of HDAC and induces histone acetylation and lysine-acetylation accumulation in vitro; (6) LC treatment induces accumulation of acetylated histones in chromatin associated with the p21(cip1) gene but not p27(kip1) detected by ChIP assay. These data support that LC, besides transporting acyl group, works as an endogenous HDAC inhibitor in the cell, which would be of physiological and pathological importance.