Antiviral Rotenoids and Isoflavones Isolated from Millettia oblata ssp. teitensis.

Three new (1-3) and six known rotenoids (5-10), along with three known isoflavones (11-13), were isolated from the leaves of Millettia oblata ssp. teitensis. A new glycosylated isoflavone (4), four known isoflavones (14-18), and one known chalcone (19) were isolated from the root wood extract of the same plant. The structures were elucidated by NMR and mass spectrometric analyses. The absolute configuration of the chiral compounds was established by a comparison of experimental ECD and VCD data with those calculated for the possible stereoisomers. This is the first report on the use of VCD to assign the absolute configuration of rotenoids. The crude leaves and root wood extracts displayed anti-RSV (human respiratory syncytial virus) activity with IC50 values of 0.7 and 3.4 µg/mL, respectively. Compounds 6, 8, 10, 11, and 14 showed anti-RSV activity with IC50 values of 0.4-10 µM, while compound 3 exhibited anti-HRV-2 (human rhinovirus 2) activity with an IC50 of 4.2 µM. Most of the compounds showed low cytotoxicity for laryngeal carcinoma (HEp-2) cells; however compounds 3, 11, and 14 exhibited low cytotoxicity also in primary lung fibroblasts. This is the first report on rotenoids showing antiviral activity against RSV and HRV viruses.

Deguelin inhibits the proliferation of human multiple myeloma cells by inducing apoptosis and G2/M cell cycle arrest: Involvement of Akt and p38 MAPK signalling pathway.

Deguelin exhibits antiproliferative activity against various cancer cell types. Previous studies have reported that deguelin exhibits pro-apoptotic activity against human cancer cells. The current study aimed at further elaborating the anticancer effects of deguelin against multiple myeloma cells. Cell growth estimations were made through MTT assay. Phase contrast microscopy was used for the analysis of the viability of multiple myeloma cells. Colony formation from multiple myeloma cells was studied using a clonogenic assay. Antioxidative assays for determining levels of glutathione (GSH) and superoxide dismutase (SOD) were carried out after treating multiple myeloma cells with deguelin. The apoptosis of multiple myeloma cells was studied using AO/EB and Annexin V-FITC/PI staining methods. Multiple myeloma cell cycle analysis was performed through flow cytometry. mRNA expression levels were depicted using qRT-PCR. Migration and invasion of multiple myeloma cells were determined with the wound-healing and transwell assays, respectively. Deguelin specifically inhibited the multiple myeloma cell growth while the normal plasma cells were minimally affected. Multiple myeloma cells when treated with deguelin exhibited remarkably lower viability and colony-forming ability. Multiple myeloma cells treated with deguelin produced more SOD and had higher GSH levels. The multiple myeloma cell growth, migration, and invasion were significantly declined by in vitro administration of deguelin. In conclusion, deguelin treatment, when applied in vitro, induced apoptotic cell death and resulted in mitotic cessation at the G2/M phase through modulation of cell cycle regulatory mRNAs in multiple myeloma cells.

Deguelin and Paclitaxel Loaded PEG-PCL Nano-Micelles for Suppressing the Proliferation and Inducing Apoptosis of Breast Cancer Cells.

BACKGROUND: Deguelin (DGL) is a natural flavonoid reported to exhibit antitumor effects in breast cancer (BC). PEG-PCL (Polyethylene Glycol- Polycaprolactone), as polymeric micelles, has biodegradability and biocompatibility. The aim of this study was to investigate whether the nanoparticular delivery system, PEG-PCL could improve the bioavailability of DGL for suppressing proliferation of BC cells. METHODS: PEG-PCL polymers were first prepared by ring-opening polymerization, and DGL and paclitaxel (PTX)-loaded PEG-PCL nano-micelles were formulated via the film dispersion method. The composition and molecular weight of PEG-PCL were analyzed by nuclear magnetic resonance and fourier Transform infrared spectroscopy (FTIR) spectra. Particle size, surface potential and hemolytic activity of micelles were assessed by dynamic light scattering, transmission electron microscopy and hemolysis assay, respectively. Then proliferation and apoptosis of MDA-MB-231 and MDA-MB-468 cells were tested with Edu staining, CCK-8, TUNEL staining, and Flow cytometer. Caspase 3 expression was also assessed by Western blot. RESULTS: Our results first indicated that PEG2000-PCL2000 was successfully synthesized. DGL and PTX-loaded PEG-PCL nano-micelles were rounded in shape with a particle size of 35.78 ± 0.35 nm and a surface potential of 2.84 ± 0.27 mV. The micelles had minimal hemolytic activity. Besides, we proved that DGL and PTX-loaded PEG-PCL nano-micelles could suppress proliferation and induce apoptosis in BC cells. The DGL and PTX-loaded PEG-PCL nano-micelles constructed in this study had a prominent inhibitory role on proliferation and a remarkable promotional role on apoptosis in BC cells. CONCLUSIONS: This study proposes that nano-micelles formed by PEG-PCL can enhance the cytotoxicity of Paclitaxel against breast cancer cells, and concurrently, the loading of Deguelin may further inhibit cell proliferation. This presents a potential for the development of a novel therapeutic strategy.

Deguelin Attenuates Non-Small-Cell Lung Cancer Cell Metastasis by Upregulating PTEN/KLF4/EMT Signaling Pathway.

Non-small-cell lung cancer (NSCLC) is the most common lung cancer and a major cause of cancer mortality worldwide. Deguelin plays a vital inhibitory role in NSCLC initiation and development. However, the downstream mechanism of deguelin-suppressed metastasis of NSCLC cells is still not completely understood. Interestingly, phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and Krüppel-like factor 4 (KLF4) also contribute to inhibition of metastasis in NSCLC cells. Here, we demonstrated that deguelin significantly upregulated PTEN and KLF4 expressions and PTEN positively upregulated KLF4 expression in NSCLC cells including A549 and PC9 cells. Moreover, overexpressions of PTEN and KLF4 inhibited the migration and invasion of NSCLC cells, an effect similar to that of deguelin. Furthermore, overexpressions of PTEN and KLF4 could suppress the epithelial-mesenchymal transition (EMT), an effect also similar to that of deguelin. Additionally, deguelin displayed a significant antitumor ability by upregulating PTEN and KLF4 expressions in mice model with NSCLC cells. Together, these results indicated that deguelin could be a potential therapeutic agent through upregulating PTEN and KLF4 expressions for NSCLC therapy.

Novel B, C-ring truncated deguelin derivatives reveals as potential inhibitors of cyclin D1 and cyclin E using molecular docking and molecular dynamic simulation.

The overexpression of cyclin D1 and cyclin E due to their oncogenic potential and amplification has been associated with a higher mortality rate in many cancers. The deguelin is a natural compound, has shown promising anti-cancer activity by directly binding cyclin D1 and cyclin E and thus suppressing its function. The C7a atomic position of deguelin structure contains a proton that generates stabilized radical, as a result, decomposed deguelin reduces its structural stability and significantly decreases its biological activity. To design deguelin derivatives with the reduced potential side effect, series of B, C-ring truncated derivatives were investigated as cyclin D1 and cyclin E inhibitors. R-group-based enumeration was implemented in the deguelin scaffold using the R-group enumeration module of Schrödinger. Drug-Like filters like, REOS and PAINs series were applied to the enumerated compound library to remove compounds containing reactive functional groups. Further, screened compounds were docked within the ligand-binding cavity of cyclin D1 and cyclin E crystal structure, using Glide SP and XP protocol to obtain docking poses. Enrichment calculations were done using SchrÖdinger software, with 1000 decoy compounds (from DUD.E database) and 60 compounds (XP best poses) along with deguelin, to validate the docking protocol. The receiver operating characteristic (ROC) curve indicates R2 = 0.94 for cyclin D1 and R2 = 0.79 for cyclin E, suggesting that the docking protocol is valid. Besides, we explored molecular dynamics simulation to probe the binding stability of deguelin and its derivatives within the binding cavity of cyclin D1 and cyclin E structures which are associated with the cyclin D1 and cyclin E inhibitory mechanism.

Pharmacological basis and new insights of deguelin concerning its anticancer effects.

Deguelin is a rotenoid of the flavonoid family, which can be extracted from Lonchocarpus, Derris, or Tephrosia. It possesses the inhibition of cancer cell proliferation by inducing apoptosis through regulating the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway, the NF-κB signaling pathway, the Wnt signaling pathway, the adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway and epidermal growth factor receptor (EGFR) signaling, activating the p38 mitogen-activated protein kinase (MAPK) pathway, repression of Bmi1, targeting cyclooxygenase-2 (COX-2), targeting galectin-1, promotion of glycogen synthase kinase-3ß (GSK3ß)/FBW7-mediated Mcl-1 destabilization and targeting mitochondria via down-regulating Hexokinases II-mediated glycolysis, PUMA-mediation, which are some crucial molecules which modulate closely cancer cell growth and metastasis. Deguelin inhibits tumor cell propagation and malignant transformation through targeting angiogenesis, targeting lymphangiogenesis, targeting focal adhesion kinase (FAK), inhibiting the CtsZ/FAK signaling pathway, targeting epithelial-mesenchymal transition (EMT), the NF-κB signaling pathway, regulating NIMA-related kinase 2 (NEK2). In addition, deguelin possesses other biological activities, such as targeting cell cycle arrest, modulation of autophagy, inhibition of hedgehog pathway, inducing differentiation of mutated NPM1 acute myeloid leukemia etc. Therefore, deguelin is a promising chemopreventive agent for cancer therapy.

Improvement of cytotoxicity of mitoxantrone and daunorubicin by candidone, tephrosin, and bavachinin.

BACKGROUND: Flavonoids have been demonstrated to have the ability of sensitizing cancer cells to chemotherapy and inverse multidrug resistance via various mechanisms, such as modulating of pumps. The therapeutic effect of candidone, tephrosin, and bavachinin in treatment of cancer, particularly to overcome multidrug resistance (MDR) is largely unknown. The capacity of these agents in sensitization of MDR cells is investigated in the current work. METHODS AND RESULTS: We analyzed the impact of candidone, tephrosin, and bavachinin, as chemosensitizer on cell cytotoxicity, P-gp and ABCG2 mRNA expression level on two multidrug resistant cells, ABCG2 overexpressing human epithelial breast cancer cell line (MCF7/MX), and P-gp overexpressing human gastric adenocarcinoma cell line (EPG85.257RDB). The inhibitory concentration of 50% (IC50) of daunorubicin in EPG85.257RDB cells in combination with IC10 of Bavachinin, Tephrosin, and Candidone were 6159 ± 948, 4186 ± 665, 730 ± 258 nM, and this data in MCF7/MX cell were 1773 ± 534, 7160 ± 405 and 3340 ± 622 nM respectively. These three flavonoids dose-dependently decreased the viability of MCF7/MX and EPG85.257RDB and significantly (p < 0.05) decreased IC50 of daunorubicin and mitoxantrone except Tephrosin in MCF7/MX cells. Candidone and Bavachinin were the most potent chemosensitizer in EPG85.257RDB and MCF7/MX cells respectively. Flavonoids did not reduce mRNA expression of P-gp and ABCG2 after 72 h treatment, except Candidone in EPG85.257RDB and Bavachinin in MCF7/MX cells. CONCLUSIONS: This effect is not time-dependent, and flavonoids have their own patterns that are cell-dependent. In general, tephrosin, candidone, and bavachinin had the potential of sensitizing MDR cells to mitoxantrone and daunorubicin.

Olive polyphenols attenuate TNF-α-stimulated M-CSF and IL-6 synthesis in osteoblasts: Suppression of Akt and p44/p42 MAP kinase signaling pathways.

BACKGROUND: Olive oil polyphenols, which possess cytoprotective activities like anti-oxidant and anti-inflammatory effects, could modulate osteoblast functions. The aim of this study is to elucidate the effects and the underlying mechanisms of hydroxytyrosol and oleuropein on the tumor necrosis factor-α (TNF-α)-induced macrophage colony-stimulating factor (M-CSF) and interleukin-6 (IL-6) synthesis in osteoblasts. METHODS: Osteoblast-like MC3T3-E1 cells were pretreated with hydroxytyrosol, oleuropein, deguelin, PD98059 or wedelolactone, and then stimulated by TNF-α. The levels of M-CSF and IL-6 in the conditioned medium were determined with ELISA. The mRNA expression levels of M-CSF or IL-6 were determined with real-time RT-PCR. The phosphorylation levels of Akt, p44/p42 mitogen-activated protein (MAP) kinase or NF-κB in the cell lysates were determined with Western blot analysis. RESULTS: Hydroxytyrosol and oleuropein attenuated the TNF-α-stimulated M-CSF release. Deguelin, an inhibitor of Akt, significantly suppressed the TNF-α-stimulated M-CSF release, which failed to be affected by the MEK1/2 inhibitor PD98059 or the IκB inhibitor wedelolactone. Hydroxytyrosol and oleuropein suppressed the TNF-α-induced phosphorylation of Akt and p44/p42 MAP kinase. Hydroxytyrosol and oleuropein attenuated the TNF-α-stimulated IL-6 release. Hydroxytyrosol suppressed the TNF-α-induced mRNA expressions of M-CSF and IL-6. Hydroxytyrosol or oleuropein failed to affect the cell viability. CONCLUSION: Our present findings strongly suggest that olive oil polyphenols hydroxytyrosol and oleuropein down-regulates TNF-α signaling at the points upstream of Akt and p44/p42 MAP kinase in osteoblasts, leading to the attenuation of M-CSF and IL-6 synthesis.

Discovery of a simplified deguelin analog as an HSP90 C-terminal inhibitor for HER2-positive breast cancer.

A series of O-substituted analogs of the C-ring-truncated scaffold of deguelin designed as heat shock protein 90 (HSP90) C-terminal inhibitors were investigated as novel antitumor agents against human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Among the synthesized compounds, compound 37 displayed significant inhibition in both trastuzumab-sensitive and trastuzumab-resistant breast cancer cells with little cytotoxicity to normal cells. Mechanistic studies of compound 37 carried out by HSP90α C-terminal inhibitor screening, the induction of the heat shock response and downregulation of HSP90 client proteins indicated that the antitumor activity of 37 in breast cancer cells could be attributed to the destabilization and inactivation of HSP90 client proteins by the binding of 37 to the C-terminal domain of HSP90. A molecular docking study of compound 37 with a HSP90 homology model indicated that its S-isomer fit well in the ATP binding site of the C-terminal domain, forming key interactions.

Deguelin targets multiple oncogenic signaling pathways to combat human malignancies.

Cancer is an anomalous growth and differentiation of cells known to be governed by oncogenic factors. Plant-based natural metabolites have been well recognized to possess chemopreventive properties. Deguelin, a natural rotenoid, is among the class of bioactive phytoconstituents from a diverse range of plants with potential antineoplastic effects in different cancer subtypes. However, the precise mechanisms of how deguelin inhibits tumor progression remains elusive. Deguelin has shown promising results in targeting the hallmarks of tumor progression via inducing tumor apoptosis, cell cycle arrest, and inhibition of angiogenesis and metastasis. Based on initial scientific excerpts, deguelin has been reported to inhibit tumor growth via different signaling pathways, including mitogen-activated protein kinase, phosphoinositide 3-kinase, serine/threonine protein kinase B (also known as Akt), mammalian target of rapamycin, nuclear factor-κB, matrix metalloproteinase (MMP)-2, MMP-9 and caspase-3, caspase-8, and caspase-9. This review summarizes the mechanistic insights of antineoplastic action of deguelin to gain a clear understanding of its therapeutic effects in cancer. The anticancer potential of deguelin with respect to its efficacy in targeting tumorigenesis via nanotechnological approaches is also investigated. The initial scientific findings have presented deguelin as a promising antitumorigenic agent which can be used for monotherapy as well as synergistically to augment efficacy of chemotherapeutic treatment regimes.

Discovery of novel anti-breast cancer agents derived from deguelin as inhibitors of heat shock protein 90 (HSP90).

A series of O-substituted analogues of the B,C-ring truncated scaffold of deguelin were designed as C-terminal inhibitors of heat shock protein 90 (HSP90) and investigated as novel antiproliferative agents against HER2-positive breast cancer. Among the synthesized compounds, compound 80 exhibited significant inhibition in both trastuzumab-sensitive and trastuzumab-resistant breast cancer cells, whereas compound 80 did not show any cytotoxicity in normal cells. Compound 80 markedly downregulated the expression of the major client proteins of HSP90 in both cell types, indicating that the cytotoxicity of 80 in breast cancer cells is attributed to the destabilization and inactivation of HSP90 client proteins and that HSP90 inhibition represents a promising strategy to overcome trastuzumab resistance. A molecular docking study of 80 with the homology model of a HSP90 homodimer showed that 80 fit nicely in the C-terminal domain with a higher electrostatic complementary score than that of ATP.

Development of a novel truncated deguelin derivative possessing nitric oxide donor as a potential anti-lung cancer agent.

Lung cancer is the leading cause of cancer death in the world. Natural product deguelin and its truncated analogs have been reported to be potential therapeutic agents for lung cancer. In order to improve the potency, a novel truncated deguelin derivative (4) possessing nitric oxide (NO) donor was designed and synthesized. The biological evaluation showed that hybrid 4 exerted potent activity with an IC50 value of 0.41 µM in H1299 cells. Mechanism studies showed that it arrested the cell cycle at G2/M phase and suppressed Hsp90 function. In addition, hybrid 4 demonstrated potent inhibitory activity on the migration and invasion of lung cancer cells. Together, the promising results warrant further development of hybrid 4 as a potential anticancer agent for the treatment of lung cancer.

Hydroxylated Rotenoids Selectively Inhibit the Proliferation of Prostate Cancer Cells.

Prostate cancer is one of the leading causes of cancer-related death in men. The identification of new therapeutics to selectively target prostate cancer cells is therefore vital. Recently, the rotenoids rotenone (1) and deguelin (2) were reported to selectively kill prostate cancer cells, and the inhibition of mitochondrial complex I was established as essential to their mechanism of action. However, these hydrophobic rotenoids readily cross the blood-brain barrier and induce symptoms characteristic of Parkinson's disease in animals. Since hydroxylated derivatives of 1 and 2 are more hydrophilic and less likely to readily cross the blood-brain barrier, 29 natural and unnatural hydroxylated derivatives of 1 and 2 were synthesized for evaluation. The inhibitory potency (IC50) of each derivative against complex I was measured, and its hydrophobicity (Slog10P) predicted. Amorphigenin (3), dalpanol (4), dihydroamorphigenin (5), and amorphigenol (6) were selected and evaluated in cell-based assays using C4-2 and C4-2B prostate cancer cells alongside control PNT2 prostate cells. These rotenoids inhibit complex I in cells, decrease oxygen consumption, and selectively inhibit the proliferation of prostate cancer cells, leaving control cells unaffected. The greatest selectivity and antiproliferative effects were observed with 3 and 5. The data highlight these molecules as promising therapeutic candidates for further evaluation in prostate cancer models.

New screening system using Twist1 promoter activity identifies dihydrorotenone as a potent drug targeting cancer-associated fibroblasts.

Cancer-associated fibroblasts (CAFs) are the most abundant stromal cells in tumor microenvironments. These cells strongly support tumor progression and are considered to be potent therapeutic targets. Therefore, drugs targeting CAFs have been developed, but most of them have failed in clinical trials. The discovery of additional drugs to inactivate or eliminate CAFs is thus essential. In this study, we developed a high-throughput screening system to find anti-CAF drugs using reporter cells that express Twist1 promoter-GFP. This screening system uses the activity of the Twist1 promoter as an indicator of CAF activation because Twist1 is known to be a central player in CAF activation. Using this screening system, we found that dihydrorotenone (DHR), an inhibitor of electron transfer chain complex 1 in mitochondria, can effectively deactivate CAFs. DHR-treated CAFs exhibited reduced expression of CAF-enriched markers, decreased capability of collagen gel contraction, and impaired ability to engage in tumor-promoting activities, such as facilitating the proliferation and colonization of cancer cells. Furthermore, conditioned media from DHR-treated CAFs attenuated tumor progression in mice grafted with MNK28 cells. In conclusion, DHR can be considered as a candidate drug targeting CAFs.

Deguelin suppresses non-small cell lung cancer by inhibiting EGFR signaling and promoting GSK3ß/FBW7-mediated Mcl-1 destabilization.

Activating mutations of epidermal growth factor receptor (EGFR) play crucial roles in the oncogenesis of human non-small cell lung cancer (NSCLC). By screening 79 commercially available natural products, we found that the natural compound deguelin exhibited a profound anti-tumor effect on NSCLC via directly down-regulating of EGFR-signaling pathway. Deguelin potently inhibited in vitro EGFR kinase activity of wild type (WT), exon 19 deletion, and L858R/T790M-mutated EGFR. The in silico docking study indicated that deguelin was docked into the ATP-binding pocket of EGFRs. By suppression of EGFR signaling, deguelin inhibited anchorage-dependent, and independent growth of NSCLC cell lines, and significantly delayed tumorigenesis in vivo. Further study showed that deguelin inhibited EGFR and downstream kinase Akt, which resulted in the activation of GSK3ß and eventually enhanced Mcl-1 phosphorylation at S159. Moreover, deguelin promoted the interaction between Mcl-1 and E3 ligase SCFFBW7, which enhanced FBW7-mediated Mcl-1 ubiquitination and degradation. Additionally, phosphorylation of Mcl-1 by GSK3ß is a prerequisite for FBW7-mediated Mcl-1 destruction. Depletion or pharmacological inactivation of GSK3ß compromised deguelin-induced Mcl-1 ubiquitination and reduction. Taken together, our data indicate that enhancement of ubiquitination-dependent Mcl-1 turnover might be a promising approach for cancer treatment.

Deguelin inhibits HCV replication through suppressing cellular autophagy via down regulation of Beclin1 expression in human hepatoma cells.

AIMS: Deguelin, a natural compound derived from Mundulea sericea (Leguminosae) and some other plants exhibits an activity to inhibit autophagy, a cellular machinery required for hepatitis C virus (HCV) replication. This study aimed to illuminate the impact of deguelin on HCV replication and mechanism(s) involved. METHODS: HCV JFH-1-Huh7 infectious system was used for the investigation. Real time RT-PCR, Western blot, fluorescent microscopy assay were used to measure the expression levels of viral or cellular factors. Overexpression and silencing expression techniques were used to determine the role of key cellular factors. RESULTS: Deguelin treatment of Huh7 cells significantly inhibited HCV JFH-1 replication in a dose- and time-dependent manner. Deguelin treatment suppressed autophagy in Huh7 cells, evidenced by the decrease of LC3B-II levels, the conversion of LC3B-I to LC3B-II, and the formation of GFP-LC3 puncta as well as the increase of p62 level in deguelin-treated cells compared with control cells. HCV infection could induce autophagy which was also suppressed by deguelin treatment. Mechanism research reveals that deguelin inhibited expression of Beclin1, which is a key cellular factor for the initiation of the autophagosome formation in autophagy. Overexpression or silencing expression of Beclin1 in deguelin-treated Huh7 cells could weaken or enhance the inhibitory effect on autophagy by deguelin, respectively, and thus partially recover or further inhibit HCV replication correspondingly. CONCLUSIONS: Deguelin may serve as a novel anti-HCV compound via its inhibitory effect on autophagy, which warrants further investigation as a potential therapeutic agent for HCV infection.

Inhibition of Cancer Stem-Like Phenotype by Curcumin and Deguelin in CAL-62 Anaplastic Thyroid Cancer Cells.

BACKGROUND: Anaplastic Thyroid Cancer (ATC) is one of the most lethal and aggressive human malignancies. Studies have shown that Cancer Stem-Cell (CSC) phenotype is mainly responsible for ATC aggressiveness. Cytostatic compounds are mostly ineffective because of multidrug resistance mechanisms driven by the CSC phenotype. Taxanes have limited efficacy. Recently, CSC inhibition using plant-derived, less toxic compounds, which have anti-cancer efficacy, has become a novel treatment modality. The aim of the study was to evaluate the anti-cancer activity of two natural compounds (curcumin and deguelin) on ATC cells and their CSC properties. In addition, the efficacies of these compounds were compared with that of docetaxel. METHODS: Besides control, five treatment groups were formed. ATC cells (CAL-62) were treated with curcumin, deguelin, docetaxel, and their combinations (curcumin+docetaxel, deguelin+docetaxel) at previously determined IC50 doses. Stemness was analyzed by quantitative estimation of sphere formation in matrigel, expression of several cell surface markers (CD133, CD90, Nanog, and OCT3/4) using flow cytometry, and quantification of the hypoxic status [Oxidative Stress Index (OSI) and Superoxide Dismutase (SOD) activity]. The anti-cancer efficacies of these compounds and their combinations were evaluated by determining the alterations in the cell cycle, apoptosis, and tumoral cell migration. RESULTS: Both the natural compounds (particularly curcumin) significantly suppressed the spheroid formation and cellular motility in matrigel as well as suppressed the accumulation of cells in the G0/1 phase, in which the maximum CSC activity is observed. The compounds did not suppress the expression of CSC markers, but twothirds of the cells expressed CD90. Deguelin was found to be particularly effective in inducing apoptosis similar to docetaxel at IC50 concentrations. Curcumin reduced the OSI and deguelin enhanced the SOD activity, even in docetaxel pre-treated cells. CONCLUSION: A large proportion of anaplastic tumors might consist of heterogeneous CSC population. Curcumin and deguelin have anti-cancer and several anti-stem cell activities against ATC cells. These natural compounds are capable of altering the aggressive behavior of ATC cells through the inhibition of the CSC phenotype. As a novel therapeutic target, CD90 should be investigated in other ATC cell lines and in vivo models.

Mitochondrial complex I inhibitor deguelin induces metabolic reprogramming and sensitizes vemurafenib-resistant BRAFV600E mutation bearing metastatic melanoma cells.

Treatment with vemurafenib, a potent and selective inhibitor of mitogen-activated protein kinase signaling downstream of the BRAFV600E oncogene, elicits dramatic clinical responses in patients with metastatic melanoma. Unfortunately, the clinical utility of this drug is limited by a high incidence of drug resistance. Thus, there is an unmet need for alternative therapeutic strategies to treat vemurafenib-resistant metastatic melanomas. We have conducted high-throughput screening of two bioactive compound libraries (Siga and Spectrum libraries) against a metastatic melanoma cell line (A2058) and identified two structurally analogous compounds, deguelin and rotenone, from a cell viability assay. Vemurafenib-resistant melanoma cell lines, A2058R and A375R (containing the BRAFV600E mutation), also showed reduced proliferation when treated with these two compounds. Deguelin, a mitochondrial complex I inhibitor, was noted to significantly inhibit oxygen consumption in cellular metabolism assays. Mechanistically, deguelin treatment rapidly activates AMPK signaling, which results in inhibition of mTORC1 signaling and differential phosphorylation of mTORC1's downstream effectors, 4E-BP1 and p70S6 kinase. Deguelin also significantly inhibited ERK activation and Ki67 expression without altering Akt activation in the same timeframe in the vemurafenib-resistant melanoma cells. These data posit that treatment with metabolic regulators, such as deguelin, can lead to energy starvation, thereby modulating the intracellular metabolic environment and reducing survival of drug-resistant melanomas harboring BRAF V600E mutations.

Biopharmacological considerations for accelerating drug development of deguelin, a rotenoid with potent chemotherapeutic and chemopreventive potential.

Deguelin is a rotenoid compound that exists in abundant quantities in the bark, roots, and leaves of the Leguminosae family of plants. An analysis of evidence from both in vitro and in vivo studies suggests that deguelin displays potent anticancer activity against multiple cancer types and exhibits chemopreventive potential in Akt-inducible transgenic mouse models. Deguelin appears to impede carcinogenesis by enhancing cell apoptosis and hindering malignant transformation and tumor cell propagation. Crucial oncogenic pathways likely targeted by deguelin include the epithelial-to-mesenchymal transition; angiogenesis-related pathways; and the phosphoinositide 3-kinase/Akt, Wnt, epidermal growth factor receptor, c-Met, and hedgehog signal transduction cascades. This review article provides a comprehensive summary of current preclinical research featuring deguelin as a leading chemotherapeutic and chemopreventive compound, and it highlights the importance of identifying companion molecular biomarkers and performing systemic pharmacokinetic studies for accelerating the process of developing deguelin as a clinical anticancer agent.

Investigation of B,C-ring truncated deguelin derivatives as heat shock protein 90 (HSP90) inhibitors for use as anti-breast cancer agents.

On the basis of deguelin, a series of the B,C-ring truncated surrogates with N-substituted amide linkers were investigated as HSP90 inhibitors. The structure activity relationship of the template was studied by incorporating various substitutions on the nitrogen of the amide linker and examining their HIF-1α inhibition. Among them, compound 57 showed potent HIF-1α inhibition and cytotoxicity in triple-negative breast cancer lines in a dose-dependent manner. Compound 57 downregulated expression and phosphorylation of major client proteins of HSP90 including AKT, ERK and STAT3, indicating that its antitumor activity was derived from the inhibition of HSP90 function. The molecular modeling of 57 demonstrated that 57 bound well to the C-terminal ATP-binding pocket in the open conformation of the hHSP90 homodimer with hydrogen bonding and pi-cation interactions. Overall, compound 57 is a potential antitumor agent for triple-negative breast cancer as a HSP90 C-terminal inhibitor.