Deguelin suppresses pancreatic tumor growth and metastasis by inhibiting epithelial-to-mesenchymal transition in an orthotopic model

Enantioselective Reduction and Sulfenylation of Isoflavanone Derivatives via Bisguanidinium Hypervalent Silicate

In this work, we describe an enantioselective reduction and sulfenylation of isoflavanone derivatives by an ion pair strategy. The chiral cationic catalyst bisguanidinium (BG) is capable of chiral induction in catalytic systems. Silane hydride works as a reductant and helps to form an anionic hypervalent silicate complex and intermediates with substrates to pair with chiral catalyst. A series of umpolung sulfur reagents accomplish electrophilic attack in the presence of a silicate anion. Both chemoselectivity and enantioselectivity are good to excellent to afford a wide scope of 4-oxo-4H-chromene-3-carbonitrile and S-electrophilic reagents. Further transformations were completed to introduce more applications.

Modulation of hypoxia-inducible factor-1 signaling pathways in cancer angiogenesis, invasion, and metastasis by natural compounds: a comprehensive and critical review

Tumor cells employ multiple signaling mediators to escape the hypoxic condition and trigger angiogenesis and metastasis. As a critical orchestrate of tumorigenic conditions, hypoxia-inducible factor-1 (HIF-1) is responsible for stimulating several target genes and dysregulated pathways in tumor invasion and migration. Therefore, targeting HIF-1 pathway and cross-talked mediators seems to be a novel strategy in cancer prevention and treatment. In recent decades, tremendous efforts have been made to develop multi-targeted therapies to modulate several dysregulated pathways in cancer angiogenesis, invasion, and metastasis. In this line, natural compounds have shown a bright future in combating angiogenic and metastatic conditions. Among the natural secondary metabolites, we have evaluated the critical potential of phenolic compounds, terpenes/terpenoids, alkaloids, sulfur compounds, marine- and microbe-derived agents in the attenuation of HIF-1, and interconnected pathways in fighting tumor-associated angiogenesis and invasion. This is the first comprehensive review on natural constituents as potential regulators of HIF-1 and interconnected pathways against cancer angiogenesis and metastasis. This review aims to reshape the previous strategies in cancer prevention and treatment.

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.

Potential Focal Adhesion Kinase Inhibitors in Management of Cancer: Therapeutic Opportunities from Herbal Medicine

Focal adhesion kinase (FAK) is a multifunctional protein involved in cellular communication, integrating and transducing extracellular signals from cell-surface membrane receptors. It plays a central role intracellularly and extracellularly within the tumor microenvironment. Perturbations in FAK signaling promote tumor occurrence and development, and studies have revealed its biological behavior in tumor cell proliferation, migration, and adhesion. Herein we provide an overview of the complex biology of the FAK family members and their context-dependent nature. Next, with a focus on cancer, we highlight the activities of FAK signaling in different types of cancer and how knowledge of them is being used for screening natural compounds used in herbal medicine to fight tumor development.

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.

The Potential for Natural Products to Overcome Cancer Drug Resistance by Modulation of Epithelial-Mesenchymal Transition

The acquisition of resistance and ultimately disease relapse after initial response to chemotherapy put obstacles in the way of cancer therapy. Epithelial-mesenchymal transition (EMT) is a biologic process that epithelial cells alter to mesenchymal cells and acquire fibroblast-like properties. EMT plays a significant role in cancer metastasis, motility, and survival. Recently, emerging evidence suggested that EMT pathways are very important in making drug-resistant involved in cancer. Natural products are gradually emerging as a valuable source of safe and effective anticancer compounds. Natural products could interfere with the different processes implicated in cancer drug resistance by reversing the EMT process. In this review, we illustrate the molecular mechanisms of EMT in the emergence of cancer metastasis. We then present the role of natural compounds in the suppression of EMT pathways in different cancers to overcome cancer cell drug resistance and improve tumor chemotherapy. HighlightsDrug-resistance is one of the obstacles to cancer treatment.EMT signaling pathways have been correlated to tumor invasion, metastasis, and drug-resistance.Various studies on the relationship between EMT and resistance to chemotherapy agents were reviewed.Different anticancer natural products with EMT inhibitory properties and drug resistance reversal effects were compared.

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-3β (GSK3β)/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.

Perspectives on natural compounds in chemoprevention and treatment of cancer: an update with new promising compounds

Cancer is the second deadliest disease worldwide. Although recent advances applying precision treatments with targeted (molecular and immune) agents are promising, the histological and molecular heterogeneity of cancer cells and huge mutational burdens (intrinsic or acquired after therapy) leading to drug resistance and treatment failure are posing continuous challenges. These recent advances do not negate the need for alternative approaches such as chemoprevention, the pharmacological approach to reverse, suppress or prevent the initial phases of carcinogenesis or the progression of premalignant cells to invasive disease by using non-toxic agents. Although data are limited, the success of several clinical trials in preventing cancer in high-risk populations suggests that chemoprevention is a rational, appealing and viable strategy to prevent carcinogenesis. Particularly among higher-risk groups, the use of safe, non-toxic agents is the utmost consideration because these individuals have not yet developed invasive disease. Natural dietary compounds present in fruits, vegetables and spices are especially attractive for chemoprevention and treatment because of their easy availability, high margin of safety, relatively low cost and widespread human consumption. Hundreds of such compounds have been widely investigated for chemoprevention and treatment in the last few decades. Previously, we reviewed the most widely studied natural compounds and their molecular mechanisms, which were highly exploited by the cancer research community. In the time since our initial review, many promising new compounds have been identified. In this review, we critically review these promising new natural compounds, their molecular targets and mechanisms of anticancer activity that may create novel opportunities for further design and conduct of preclinical and clinical studies.

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.

An Electrophilic Deguelin Analogue Inhibits STAT3 Signaling in H-Ras-Transformed Human Mammary Epithelial Cells: The Cysteine 259 Residue as a Potential Target

Signal transducer and activator of transcription 3 (STAT3) is a point of convergence for numerous oncogenic signals that are often constitutively activated in many cancerous or transformed cells and some stromal cells in the tumor microenvironment. Persistent STAT3 activation in malignant cells stimulates proliferation, survival, angiogenesis, invasion, and tumor-promoting inflammation. STAT3 undergoes activation through phosphorylation on tyrosine 705, which facilitates its dimerization. Dimeric STAT3 translocates to the nucleus, where it regulates the transcription of genes involved in cell proliferation, survival, etc. In the present study, a synthetic deguelin analogue SH48, discovered by virtual screening, inhibited the phosphorylation, nuclear translocation, and transcriptional activity of STAT3 in H-ras transformed human mammary epithelial MCF-10A cells (MCF10A-ras). We speculated that SH48 bearing an α,β-unsaturated carbonyl group could interact with a thiol residue of STAT3, thereby inactivating this transcription factor. Non-electrophilic analogues of SH48 failed to inhibit STAT3 activation, lending support to the above supposition. By utilizing a biotinylated SH48, we were able to demonstrate the complex formation between SH48 and STAT3. SH48 treatment to MCF10A-ras cells induced autophagy, which was verified by staining with a fluorescent acidotropic probe, LysoTracker Red, as well as upregulating the expression of LC3II and p62. In conclusion, the electrophilic analogue of deguelin interacts with STAT3 and inhibits its activation in MCF10A-ras cells, which may account for its induction of autophagic death.

Rotenone restrains colon cancer cell viability, motility and epithelial‑mesenchymal transition and tumorigenesis in nude mice via the PI3K/AKT pathway

Rotenone, a natural hydrophobic pesticide, has been reported to display anticancer activity in a variety of cancer cells. However, the mechanism of rotenone on colon cancer (CC) cell migration, invasion and metastasis is still unknown. In the present study, the cytotoxicity of rotenone on CC cells were detected by the Cell Counting Kit‑8 assay and confirmed by clone formation assay. The effects of rotenone on CC cell invasion and migration activity were determined in vitro by Transwell invasion and wound healing assays, respectively. In addition, to reveal whether rotenone affected the epithelial‑mesenchymal‑transition (EMT) process, reverse transcription‑quantitative PCR, western blotting and immunofluorescence assays were used to detect the expression of EMT markers. The expression levels of the key markers of the PI3K/AKT pathway after rotenone treatment alone or in combination with a PI3K/AKT signaling activator in CC were also detected by western blotting. Finally, the in vivo antitumor effects of rotenone were evaluated in a subcutaneous xenotransplant tumor model treated with an intraperitoneal injection of rotenone. The results of the present study demonstrated that rotenone treatment induced CC cell cytotoxicity and greater effects were observed with increasing concentrations and inhibited cell proliferation compared with untreated cells. In vitro cell function assays revealed that rotenone inhibited CC cell migration, invasion and EMT compared with untreated cells. Mechanically, the phosphorylation levels of AKT and mTOR were downregulated in rotenone‑treated CC cells compared with untreated cells. Additionally, AKT and mTOR phosphorylation levels were increased by the PI3K/AKT signaling activator insulin‑like growth factor 1 (IGF‑1), which was reversed by rotenone treatment. The cell function assays confirmed that the IGF‑1‑activated cell proliferation, migration and invasion were decreased by rotenone treatment. These results indicated that rotenone affected CC cell proliferation and metastatic capabilities by inhibiting the PI3K/AKT/mTOR signaling pathway. In addition, rotenone inhibited tumor growth and metastatic capability of CC, which was confirmed in a xenograft mouse model. In conclusion, the present study revealed that rotenone inhibited CC cell viability, motility, EMT and metastasis in vitro and in vivo by inhibiting the PI3K/AKT/mTOR signaling pathway.

MicroRNA-126 exerts antitumor functions in ovarian cancer by targeting EGFL7 and affecting epithelial-to-mesenchymal transition and ERK/MAPK signaling pathway

Ovarian cancer (OC) is a common gynecological malignant carcinoma worldwide. Accumulating research has revealed that multiple microRNAs (miRNAs) are abnormally expressed at different levels in various malignancies, playing vital roles in tumorigenesis. This study investigated the regulatory functions and potential mechanism of miR-126 in OC proliferation, invasion and migration. It was found that miR-126 was prominently downregulated in OC. Moreover, the decrease of miR-126 promoted the aggressive phenotypes and indicated poor prognosis of OC patients. Functional assays demonstrated that restoration of miR-126 dramatically repressed OC cell proliferation, migration and invasion. Furthermore, luciferase reporter assay was conducted to verify putative binding sites of miR-126 in the epidermal growth factor-like domain 7 (EGFL7) 3 untranslated region (3'UTR), indicating that EGFL7 was a target gene of miR-126 in OC cells. It was further discovered that miR-126 exerts its function on regulating ERK/MAPK pathway and epithelial-to-mesenchymal transition (EMT) in OC cells. The above findings suggested that miR-126 served as a cancer suppressor in OC, suggesting a promising application of miR-126 in the clinical diagnosis and therapeutics of OC.

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.

The Anticancer Properties of Tanshinones and the Pharmacological Effects of Their Active Ingredients

Cancer is a common malignant disease worldwide with an increasing mortality in recent years. Salvia miltiorrhiza, a well-known traditional Chinese medicine, has been used for the treatment of cardiovascular and cerebrovascular diseases for thousands of years. The liposoluble tanshinones in S. miltiorrhiza are important bioactive components and mainly include tanshinone IIA, dihydrodanshinone, tanshinone I, and cryptotanshinone. Previous studies showed that these four tanshinones exhibited distinct inhibitory effects on tumor cells through different molecular mechanisms in vitro and in vivo. The mechanisms mainly include the inhibition of tumor cell growth, metastasis, invasion, and angiogenesis, apoptosis induction, cell autophagy, and antitumor immunity, and so on. In this review, we describe the latest progress on the antitumor functions and mechanisms of these four tanshinones to provide a deeper understanding of the efficacy. In addition, the important role of tumor immunology is also reviewed.

Promising Potential of Lonchocarpus utilis against South American Myasis

Traditional medicine is especially important in the treatment of neglected tropical diseases because it is the way the majority of populations of affected countries manage primary healthcare. We present a case study that can serve as an example that can be replicated by others in the same situation. It is about the validation of a local remedy for myasis in Amazonian Ecuador, which is contrasted by bibliographic chemical reviews and in silico activity tests. We look for scientific arguments to demonstrate the reason for using extracts of Lonchocarpus utilis against south American myasis (tupe). We provide a summary of the isoflavonoids, prenylated flavonoids, chalcones, and stilbenes that justify the action. We make modeling predictions on the affinity of eight chemical components and enzyme targets using Swiss Target Prediction software. We conclude that the effects of this extract can be reasonably attributed to an effect of the parasite that causes the disease, similar to the one produced by synthetic drugs used by conventional medicine (e.g., Ivermectine).

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.

Prevention of epithelial to mesenchymal transition in colorectal carcinoma by regulation of the E-cadherin-β-catenin-vinculin axis

Epithelial to mesenchymal transition (EMT) is compulsory for metastatic dissemination and is stimulated by TGF-β. Although targeting EMT has significant therapeutic potential, very few pharmacological agents have been shown to exert anti-metastatic effects. BI-69A11, a competitive Akt inhibitor, displays anti-tumor activity toward melanoma and colon carcinoma. This study provides molecular and biochemical insights into the effects of BI-69A11 on EMT in colon carcinoma cells in vitro and in vivo. BI-69A11 inhibited metastasis-associated cellular migration, invasion and adhesion by inhibiting the Akt-β-catenin pathway. The underlying mechanism of BI-69A11-mediated inhibition of EMT included suppression of nuclear transport of β-catenin and diminished phosphorylation of β-catenin, which was accompanied by enhanced E-cadherin-β-catenin complex formation at the plasma membrane. Additionally, BI-69A11 caused increased accumulation of vinculin in the plasma membrane, which fortified focal adhesion junctions leading to inhibition of metastasis. BI-69A11 downregulated activation of the TGF-β-induced non-canonical Akt/NF-κB pathway and blocked TGF-β-induced enhanced expression of Snail causing restoration of E-cadherin. Overall, this study enhances our understanding of the molecular mechanism of BI-69A11-induced reversal of EMT in colorectal carcinoma cells in vitro, in vivo and in TGF-β-induced model systems.

Deguelin induces apoptosis in colorectal cancer cells by activating the p38 MAPK pathway

Objectives

Deguelin, a rotenoid extracted from Mundulea sericea (Leguminosae), exhibits antitumor effects on several types of human cancers. Due to the limited studies of deguelin on colorectal cancer (CRC), the present study was designed to investigate the antitumor effect of deguelin and to explore the underlying mechanism in CRC.

Materials and methods

Cell viability was assessed by the cell counting kit-8 (CCK-8) assay, and cell apoptosis was determined by the annexin v-propidium iodide staining using flow cytometry and Western blot in CRC cell lines after incubation with deguelin. The antitumor effect of deguelin was further evaluated in tumor xenograft models. Moreover, SB203580, a specific inhibitor of p38 MAPK, was used to confirm the involvement of p38 MAPK pathway in deguelin-induced apoptosis.

Results

Deguelin significantly inhibited cell proliferation and induced apoptosis in CRC cell lines (SW620 and RKO) in a time-dependent and dose-dependent manner. Western blot analysis also showed that the expression of proapoptotic proteins (cleaved caspase 3 and cleaved PARP) was upregulated, while that of antiapoptotic proteins (Bcl-2 and survivin) was downregulated after deguelin treatment in CRC cell lines. Moreover, oral administration of deguelin significantly suppressed tumor growth and induced apoptosis in subcutaneous xenograft mouse models without obvious toxicity. Additionally, Western blot revealed that deguelin-induced apoptosis might be regulated by the p38 MAPK pathway and inhibition of p38 MAPK could attenuate deguelin-induced proliferative inhibition and apoptosis in CRC cells.

Conclusion

Collectively, these results demonstrated that deguelin inhibited CRC cell growth by inducing apoptosis via activation of p38 MAPK pathway.

The Natural Flavonoid Compound Deguelin Inhibits HCMV Lytic Replication within Fibroblasts

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus for which there is no vaccine or cure. This viral infection, once acquired, is life-long, residing latently in hematopoietic cells. However, latently infected individuals with weakened immune systems often undergo HCMV reactivation, which can cause serious complications in immunosuppressed and immunocompromised patients. Current anti-viral therapies target late stages of viral replication, and are often met with therapeutic resistance, necessitating the development of novel therapeutics. In this current study, we identified a naturally-occurring flavonoid compound, deguelin, which inhibits HCMV lytic replication. Our findings reveal that nanomolar concentrations of deguelin significantly suppress the production of the infectious virus. Further, we show that deguelin inhibits the lytic cycle during the phase of the replication cycle consistent with early (E) gene and protein expression. Importantly, our data reveal that deguelin inhibits replication of a ganciclovir-resistant strain of HCMV. Together, our findings identify a novel, naturally occurring compound that may prove useful in the treatment of HCMV replication.

Repression of Noxa by Bmi1 contributes to deguelin-induced apoptosis in non-small cell lung cancer cells

Deguelin, a natural rotenoid isolated from several plants, has been reported to exert anti‐tumour effects in various cancers. However, the molecular mechanism of this regulation remains to be fully elucidated. Here, we found that deguelin inhibited the growth of non‐small cell lung cancer (NSCLC) cells both in vitro and in vivo by downregulation of Bmi1 expression. Our data showed that Bmi1 is highly expressed in human NSCLC tissues and cell lines. Knockdown of Bmi1 significantly suppressed NSCLC cell proliferation and colony formation. Deguelin treatment attenuated the binding activity of Bmi1 to the Noxa promoter, thus resulting in Noxa transcription and apoptosis activation. Knockdown of Bmi1 promoted Noxa expression and enhanced deguelin‐induced apoptosis, whereas overexpression of Bmi1 down‐regulated Noxa protein level and deguelin‐induced apoptosis. Overall, our study demonstrated a novel apoptotic mechanism for deguelin to exert its anti‐tumour activity in NSCLC cells.

Deguelin attenuates non-small cell lung cancer cell metastasis through inhibiting the CtsZ/FAK signaling pathway

Lung cancer is the leading cause of cancer-related death among both men and women every year, mainly due to metastasis. Although natural compound deguelin has been reported to inhibited cell migration and invasion in various cancer cells, the details of this regulation progress remain to be fully elucidated. In this study, we investigated the underlying mechanism of deguelin-suppressed metastasis of non-small cell lung cancer (NSCLC) cells. Our results demonstrate that deguelin inhibits NSCLC cell migration, invasion, and metastasis both in vitro and in vivo. These inhibitory effects of deguelin were mediated by suppressing of Cathepsin Z (CtsZ) expression and interrupting the interaction of CtsZ with integrin β3. Moreover, deguelin inhibits the activation of CtsZ downstream FAK/Src/Paxillin signaling. Knockdown of CtsZ mimicked the effect of deguelin on NSCLC cells migration and invasion. Our study reveals that deguelin exerts its anti-metastatic effect both in vitro and in vivo is partly dependent on the suppression of CtsZ signaling. Deguelin would be a potential anti-metastasis agent against NSCLC.

HS-173, a novel PI3K inhibitor suppresses EMT and metastasis in pancreatic cancer

Pancreatic cancer is one of the most aggressive solid malignancies prone to metastasis. Epithelial-mesenchymal transition (EMT) contributes to cancer invasiveness and drug resistance. In this study, we investigated whether HS-173, a novel PI3K inhibitor blocked the process of EMT in pancreatic cancer. HS-173 inhibited the growth of pancreatic cancer cells in a dose- and time-dependent manner. Moreover, it significantly suppressed the TGF-β-induced migration and invasion, as well as reversed TGF-β-induced mesenchymal cell morphology. Also, HS-173 reduced EMT by increasing epithelial markers and decreasing the mesenchymal markers by blocking the PI3K/AKT/mTOR and Smad2/3 signaling pathways in pancreatic cancer cells. In addition, HS-173 clearly suppressed tumor growth without drug toxicity in both xenograft and orthotopic mouse models. Furthermore, to explore the anti-metastatic effect of HS-173, we established pancreatic cancer metastatic mouse models and found that it significantly inhibited metastatic dissemination of the primary tumor to liver and lung. Taken together, our findings demonstrate that HS-173 can efficiently suppress EMT and metastasis by inhibiting PI3K/AKT/mTOR and Smad2/3 signaling pathways, suggesting it can be a potential candidate for the treatment of advanced stage pancreatic cancer.

Deguelin exerts anticancer activity of human gastric cancer MGC-803 and MKN-45 cells in vitro

During the pathogenesis of gastric cancer, Akt signaling is considered as a pivotal inducer of gastric cancer development. Here we report the identification of anticancer activities of deguelin, a natural agent that inhibits Akt signaling. When applied to MGC-803 and MKN-45 cells, deguelin suppressed the proliferation and arrested cell cycle by p21-mediated inhibition of cyclin E. We further present in vitro evidence that deguelin promoted apoptosis of cancer cells by decreasing the phospho-Akt signaling and affecting expression of the apoptosis-associated genes Bax and Bcl-2. Additionally, deguelin was found to suppress the migration and invasion of gastric cancer cells. Taken together, these results indicated that deguelin exerted anticancer activity of human gastric cancer MGC-803 and MKN-45 cells in vitro.

Deguelin induced differentiation of mutated NPM1 acute myeloid leukemia in vivo and in vitro

Nucleophosmin (NPM1), a restricted nucleolar localization protein, shuttles between the nucleus and the cytoplasm. Mutated (Mt)-NPM1 protein, which has aberrant cytoplasmic dislocation of nucleophosmin, occurs in approximately one-third of acute myeloid leukemia cases. Deguelin, a rotenoid isolated from several plant species, is a strong antitumor agent. NOD/SCID mice xenografted with human Mt-NPM1 OCI/AML3 cell lines served as in-vivo models. Wright-Giemsa staining and flow cytometry analysis were used for differentiation assays. Associated molecular events were assessed by western blot and histological analyses. Kaplan-Meier estimates were used to calculate survival. Deguelin toxicity in mice was assessed by immunohistochemistry staining and serum markers. Clinical samples were differentiated by flow cytometry analysis. Deguelin induced differentiation by downregulating the Mt-NPM1 protein levels, which was accompanied by a decrease in SIRT1, p21, and HDAC1 and an increase in CEBPβ and granulocyte colony-stimulating factor receptor protein expression levels. A low-deguelin dose prolonged survival compared with the control group, and there were no apparent lesions to the brain, liver, heart, and kidney in vivo. In clinical samples, deguelin induced the differentiation of fresh blasts with Mt-NPM1 protein, but not with the wild-type NPM1 protein. Taken together, these findings further provide new evidence that the Mt-NPM1 protein plays an important role in inducing differentiation in vivo and in vitro. Mutated NPM1 protein may be a therapeutic target of deguelin in acute myeloid leukemia with the NPM1 mutation.

Stereocontrolled Semisyntheses of Elliptone and 12aβ-Hydroxyelliptone

Operationally simple, stereocontrolled semisyntheses of the anticancer rotenoids elliptone and 12aβ-hydroxyelliptone, isolated from Derris elliptica and Derris trifoliata, respectively, are described. Inspired by the work of Singhal, elliptone was prepared from rotenone via a dihydroxylation-oxidative cleavage, chemoselective Baeyer-Villiger oxidation, and acid-catalyzed elimination sequence. Elaboration of elliptone to 12aβ-hydroxyelliptone was achieved via a diastereoselective chromium-mediated Étard-like hydroxylation. The semisynthesis of elliptone constitutes an improvement over previous methods in terms of safety, scalability, and yield, while the first synthesis of 12aβ-hydroxyelliptone is also described.

Synthetic 8-hydroxydeoxyguanosine inhibited metastasis of pancreatic cancer through concerted inhibitions of ERM and Rho-GTPase

8-hydroxydeoxyguanosine (8-OHdG) is generated consequent to oxidative stress, but its paradoxical anti-oxidative, anti-inflammatory, and anti-mutagenic effects via Rho-GTPase inhibition were noted in various models of inflammation and cancer. Metastasis occurs through cell detachment, epithelial-mesenchymal transition (EMT), and cell migration; during these processes, changes in cell morphology are initiated through Rho-GTPase-dependent actin cytoskeleton polymerization. In this study, we explored the anti-metastatic mechanisms of 8-OHdG in Panc-1 pancreatic cancer cells. 8-OHdG inhibits cell migration by inactivating ERM and Rho-GTPase proteins, and inhibiting focal adhesion kinase (FAK) and matrix metalloproteinases (MMPs). At 15min, 8-OHdG significantly inactivated ERM (p < 0.05) and led to a significant retardation of wound healing; siERM and H1152 (ROCK inhibitor) had similar effects (p < 0.05). However, FAK inhibitor 14, DPI (NOX inhibitor), and NAC (antioxidant) significantly delayed wound healing without inhibiting ERM or CD44 (p < 0.05). In the experiments on cell migration, siERM, siCD44, DPI, and 8-OHdG significantly inhibited MMPs. 8-OHdG significantly decreased DCF-DA activation in Panc-1 pancreatic cancer cells and down-regulated NOXs (nox-1, nox-2, and nox-3). Finally, all of these anti-migration actions of 8-OHdG resulted in significant inhibition of EMT, as evidenced by the up-regulation of ZO-1 and claudin-1 and down-regulation of vimentin. We found significant inhibition of lung metastasis of Panc-1 cells by 8-OHdG. In conclusion, exogenous 8-OHdG had potent anti-metastasis effects mediated by either ERM or Rho GTPase inhibition in metastasis-prone pancreatic cancer cells.

MicroRNA-1285-5p influences the proliferation and metastasis of non-small-cell lung carcinoma cells via downregulating CDH1 and Smad4

Abnormal expression of microRNAs has been reported to regulate gene expression and cancer cell growth, invasion, and migration. Recently, upregulation of hsa-miR-1285 was demonstrated in bronchoalveolar lavage fluid samples from patients with lung cancer and downregulation in plasma level of stage-I lung cancer patients. However, the function and the underlying mechanism of miR-1285 in non-small-cell lung carcinoma have not been elucidated. In this study, we found that miR-1285-5p, the mature form of miR-1285, was significantly upregulated in human non-small-cell lung carcinoma cell lines A549 and SK-MES-1. Additionally, cells transfected with the miR-1285-5p inhibitor LV-anti-miR-1285-5p demonstrated significantly inhibited proliferation and invasion and depressed migration. Further analysis demonstrated that the miR-1285-5p precursor LV-miR-1285-5p attenuated the expression of Smad4 and cadherin-1 (CDH1) but that LV-anti-miR-1285-5p showed opposite results. A luciferase reporter assay confirmed that miR-1285-5p targeted Smad4 and CDH1. Mechanism analyses revealed that silence of Smad4 and CDH1 significantly attenuated the inhibitory effects of LV-anti-miR-1285-5p on non-small-cell lung carcinoma growth and invasion. Taken together, our data suggest that miR-1285-5p functions as a tumor promoter in the development of non-small-cell lung carcinoma by targeting Smad4 and CDH1, indicating a novel therapeutic strategy for non-small-cell lung carcinoma patients.

Deguelin inhibits epithelial-to-mesenchymal transition and metastasis of human non-small cell lung cancer cells by regulating NIMA-related kinase 2

Background

Non‐small cell lung cancer is a lethal malignancy with a high mortality rate. Deguelin displays an anti‐tumor effect and inhibits metastasis in various cancers. The aberrant expression of NIMA‐related kinase 2 (NEK2) indicates poor prognosis and induces epithelial‐to‐mesenchymal transition (EMT) and metastasis processes. However, the underlying mechanism between deguelin and NEK2 has remained elusive.

Methods

NSCLC cell lines were treated with deguelin. Wound‐healing and invasion assays were applied to study the inhibitory effect of deguelin on NSCLC cells. EMT markers, E‐cadherin and Vimentin, were also detected by Western blot. NEK2 protein and messenger RNA expression levels were evaluated when NSCLC cells were treated with different concentrations of deguelin. The effect of NEK2 on NSCLC cell metastasis was evaluated through NEK2 knockdown. To investigate whether deguelin induced EMT by regulating NEK2, we overexpressed NEK2 in both NCI‐H520 and SK‐MES‐1 cell lines, and then used real time‐PCR to study the E‐cadherin and Vimentin messenger RNA expression in both NSCLC cells.

Results

Deguelin inhibited migration and invasion processes in NSCLC cell lines and decreased NEK2 expression in a concentration‐dependent manner. Furthermore, NEK2 knockdown inhibited NSCLC cell migration and invasion. Finally, overexpressing NEK2 in NCI‐H520 and SK‐MES‐1 cells could restore the inhibition of metastasis induced by deguelin.

Conclusions

Deguelin could inhibit EMT and metastasis, while overexpression of NEK2 promotes these processes. Deguelin could decrease NEK2 expression, while NEK2 overexpression could restore deguelin‐induced inhibition of metastasis.

Stereocontrolled semi-syntheses of deguelin and tephrosin

We describe stereocontrolled semi-syntheses of deguelin and tephrosin, anti-cancer rotenoids isolated from Tephrosia vogelii. Firstly, we present a new two-step transformation of rotenone into rot-2'-enonic acid via a zinc-mediated ring opening of rotenone hydrobromide. Secondly, following conversion of rot-2'-enonic acid into deguelin, a chromium-mediated hydroxylation provides tephrosin as a single diastereoisomer. An Étard-like reaction mechanism is proposed to account for the stereochemical outcome. Our syntheses of deguelin and tephrosin are operationally simple, scalable and high yielding, offering considerable advantages over previous methods.

Inhibition of Autophagy by Deguelin Sensitizes Pancreatic Cancer Cells to Doxorubicin

Pancreatic cancer is the fourth most common cause of cancer mortality worldwide. Furthermore, patients with pancreatic cancer experience limited benefit from current chemotherapeutic approaches because of drug resistance. Therefore, an effective therapeutic strategy for patients with pancreatic cancer is urgently required. Deguelin is a natural chemopreventive drug that exerts potent antiproliferative activity in solid tumors by inducing cell death. However, the molecular mechanisms underlying this activity have not been fully elucidated. Here we show that deguelin blocks autophagy and induces apoptosis in pancreatic cancer cells in vitro. Autophagy induced by doxorubicin plays a protective role in pancreatic cancer cells, and suppressing autophagy by chloroquine or silencing autophagy protein 5 enhanced doxorubicin-induced cell death. Similarly, inhibition of autophagy by deguelin also chemosensitized pancreatic cancer cell lines to doxorubicin. These findings suggest that deguelin has potent anticancer effects against pancreatic cancer and potentiates the anti-cancer effects of doxorubicin. These findings provide evidence that combined treatment with deguelin and doxorubicin represents an effective strategy for treating pancreatic cancer.

Changes in mitochondrial function during EMT induced by TGFβ-1 in pancreatic cancer

Mitochondrial dysfunction is linked to cancer. Differences in the number, morphology and function of mitochondria have been observed between normal cells and cancer cells. However, changes in mitochondrial function during epithelial-mesenchymal transition (EMT) in pancreatic cancer are less known. In the present study, the cultured human pancreatic cancer cell line Panc-1 was treated with transforming growth factor (TGF)β-1. Mitochondrial functions following TGFβ-1 exposure in pancreatic cancer were investigated. It was noticed that TGFβ-1 treatment induces morphologic changes and a shift from epithelial to mesenchymal phenotype in pancreatic cancer. Furthermore, increased mitochondrial mass was detected in pancreatic cancer following TGFβ-1 treatment. Besides, the production of reactive oxygen species in TGFβ-1-treated pancreatic cancer cells significantly increased compared with the control cells. Our results indicate that the phenomenon of EMT in pancreatic cancer has an association with mitochondrial dysfunction. Mitochondrial dysfunction may be a cause of EMT in pancreatic cancer, which leads to heterogeneity in pancreatic cancer, and may be a potential therapeutic target in the future.

Overexpression of Mcl-1 confers resistance to BRAFV600E inhibitors alone and in combination with MEK1/2 inhibitors in melanoma

Melanoma harboring BRAF mutations frequently develop resistance to BRAF inhibitors, limiting the impact of treatment. Here, we establish a mechanism of resistance and subsequently identified a suitable drug combination to overcome the resistance. Single treatment of BRAF mutant melanoma cell lines with vemurafenib or dabrafenib (BRAF inhibitors) alone or in combination with trametinib (MEK1/2 inhibitor) resulted in overexpression of Mcl-1. Overexpression of Mcl-1 in A375 and SK-MEL-28 by transfection completely blocked BRAF and MEK1/2 inhibitor-mediated inhibition of cell survival and apoptosis. Melanoma cells resistant to BRAF inhibitors showed massive expression of Mcl-1 as compared to respective sensitive cell lines. Silencing of Mcl-1 using siRNA completely sensitized resistant melanoma cells to growth suppression and induction of apoptosis by BRAF inhibitors. In vivo, vemurafenib resistant A375 xenografts implanted in athymic nude mice showed substantial tumor growth inhibition when treated with a combination of vemurafenib and Mcl-1 inhibitor or siRNA. Immunohistochemistry and western blot analyses demonstrated enhanced expression of Mcl-1 and activation of ERK1/2 in vemurafenib-resistant tumors whereas level of Mcl-1 or p-ERK1/2 was diminished in the tumors of mice treated with either of the combination. Biopsied tumors from the patients treated with or resistant to BRAF inhibitors revealed overexpression of Mcl-1. These results suggest that the combination of BRAF inhibitors with Mcl-1 inhibitor may have therapeutic advantage to melanoma patients with acquired resistance to BRAF inhibitors alone or in combination with MEK1/2 inhibitors.

Deguelin Induces the Apoptosis of Lung Squamous Cell Carcinoma Cells through Regulating the Expression of Galectin-1

Lung cancer is the leading cause of cancer mortality around the world. Despite advances in the targeted therapy, patients with lung squamous cell carcinoma(SCC) still benefit few from it, and the search for potential effective therapies is imperative. Here, we demonstrated that deguelin induced significant apoptosis of lung SCC cells in vitro. Importantly, we found deguelin down-regulated the expression of galectin-1, which was involved in a wide range of tumorous physiologic process. Thus, we both over-expressed and down-regulated galectin-1 to perform its role in deguelin-induced apoptosis. We found that increased galectin-1 attenuated apoptosis of SCC cells exposed to deguelin, while galectin-1 knockdown sensitized lung cancer cells to deguelin treatment. Additionally, we observed that down-regulation of galectin-1 resulted in suppression of Ras/Raf/ERK pathway which was involved in deguelin-induced cell apoptosis. We also found that deguelin had a significant anti-tumor ability with decline of galectin-1 in vivo. In conclusion, these findings confirm that deguelin may act as a new chemo-preventive agent through inducing apoptosis of lung SCC cells in a galectin-1 dependent manner.

Deguelin inhibits vasculogenic function of endothelial progenitor cells in tumor progression and metastasis via suppression of focal adhesion

Deguelin is a nature-derived chemopreventive drug. Endothelial progenitor cells (EPCs) are bone-marrow (BM)-derived key components to induce new blood vessels in early tumorigenesis and metastasis. Here we determined whether deguelin inhibits EPC function in vitro and in vivo at doses not affecting cancer cell apoptosis. Deguelin significantly reduced the number of EPC colony forming units of BM-derived c-kit+/sca-1+ mononuclear cells (MNCs), proliferation, migration, and adhesion to endothelial cell monolayers, and suppressed incorporation of EPC into tube-like vessel networks when co-cultured with endothelial cells. Deguelin caused cell cycle arrest at G1 without induction of apoptosis in EPC. In a mouse tumor xenograft model, tumor growth, lung metastasis and tumor-induced circulating EPCs were supressed by deguelin treatment (2 mg/kg). In mice tranplanted with GFP-expressing BM-MNCs, deguelin reduced the co-localization of CD31 and GFP, suggesting suppression of BM-derived EPC incoporation into tumor vessels. Interestingly, focal adhesion kinase (FAK)-integrin-linked kinase (ILK) activation and actin polymerization were repressed by deguelin. Decreased number of focal adhesions and a depolarized morphology was found in deguelin-treated EPCs. Taken together, our results suggest that the deguelin inhibits tumorigenesis and metastasis via EPC suppression and that suppression of focal adhesion by FAK-integrin-ILK-dependent actin remodeling is a key underlying molecular mechanism.

Deguelin-induced blockade of PI3K/protein kinase B/MAP kinase signaling in zebrafish and breast cancer cell lines is mediated by down-regulation of fibroblast growth factor receptor 4 activity

Deguelin, a natural component derived from leguminous plants, has been used as pesticide in some regions. Accumulating evidence show that deguelin has promising chemopreventive and therapeutic activities against cancer cells. This study shows that low concentrations of deguelin can lead to significant delay in zebrafish embryonic development through growth inhibition and induction of apoptosis. Furthermore, we identified fibroblast growth factor receptor 4 (FGFR4) as the putative target of deguelin. The candidate was initially identified by a microarray approach and then validated through in vitro experiments using hormone‐responsive (MCF‐7) and nonresponsive (MDA‐MB‐231) human breast cancer cell lines. The results show that deguelin suppressed cell proliferation and induced apoptosis in both cancer cell lines, but not in Hs 578Bst cells, by blocking PI3K/AKT and mitogen‐activated protein kinases (MAPK) signaling. The FGFR4 mRNA and protein level also diminished in a dose‐dependent manner. Interestingly, we found that forced FGFR4 overexpression attenuated deguelin‐induced proliferative suppression and apoptotic cell death in both zebrafish and MCF‐7 cell lines, p‐AKT and p‐ERK levels were restored upon FGFR4 overexpression. Taken together, our results strongly suggest that deguelin inhibition of PI3K/AKT and MAPK signaling in zebrafish and breast cancer cell lines is partially mediated through down‐regulation of FGFR4 activity.

Radiation Exposure Promotes Hepatocarcinoma Cell Invasion through Epithelial Mesenchymal Transition Mediated by H2S/CSE Pathway

There is growing evidence to suggest that radiotherapy can paradoxically promote tumor invasion and metastatic processes, however, the underlying molecular mechanisms remain obscure. In this study, we found that exposure to X rays promoted cell invasion by triggering the epithelial mesenchymal transition (EMT) in two hepatocellular carcinoma (HCC) cell lines, HepG2 and PLC/PRF/5. This was made evident by a reduced expression of E-cadherin and enhanced expressions of N-cadherin, Vimentin and Snail. Moreover, exposure to radiation stimulated the signaling of hydrogen sulfide (H2S), a newly found gas transmitter, by upregulating the expressions of H2S-producing proteins of cysthionine-γ-lyase (CSE), cystathionine-β-synthase (CBS). Inhibition of CSE by siRNA or inhibitor not only increased the radiosensitivity but also strongly suppressed radiation-enhanced invasive properties of HCC cells. Interestingly, we found that H2S/CSE inhibition attenuated radiation-enhanced EMT, and the above effect was an end result of blockage of the radiation-activated pathway of p38 mitogen-activated protein kinase (p38MAPK). Collectively, our findings indicate that radiation could promote HCC cell invasion through EMT mediated by endogenous H2S/CSE signaling via the p38MAPK pathway.

Deguelin inhibits the migration and invasion of lung cancer A549 and H460 cells via regulating actin cytoskeleton rearrangement

Deguelin, the main components from Mundulea sericea, was reported to suppress the growth of various cancer cells. However, the effect of Deguelin on tumor cell invasion and metastasis and its mechanism still unclear so far. In this study, we investigated the effects of Deguelin on the cell invasion in human lung cancer A549 and H460 cells. Our results demonstrate that Deguelin can significantly inhibited cell proliferation, cell migration and cell invasion. Moreover, Deguelin could also affected reorganization of the actin cytoskeleton and decreased filopodia and lamellipodia formation. Furthermore, deguelin-treated tumors showed decreased the tumor metastasis related genes such as CD44, MMP2 and MMP9 at protein and mRNA levels and the content of CEA, SCC, NSE, CYFAR21-1. In addition, Deguelin down-regulated protein expression of Rac1 and Rock1, which are impotent in actin cytoskeleton rearrangements and cell motility. Together, our results suggest that Deguelin inhibit tumor growth and metastasis of lung cancer cells and might be a candidate compound for curing lung cancer.

Regulation of epithelial-mesenchymal transition by tumor-associated macrophages in cancer

It should be urgently better understood of the mechanism that contributes cancer aggressiveness. Epithelial-mesenchymal transition (EMT) plays a fundamental role in tumor progression and metastasis formation by invasion, resistance to cell death and senescence, resistance to chemotherapy and immunotherapy, immune surveillance, immunosuppression and inflammation, confers stem cell properties. Tumor-associated macrophages (TAMs) are key orchestrators and a set of macrophages in tumor microenvironment. They are major players in the connection between inflammation and cancer. TAMs could promote proliferation, invasion and metastasis of tumor cells, stimulate tumor angiogenesis, and inhibit anti-tumor immune response mediated by T cell followed by promoting tumor progression. Recently, studies showed that TAMs played critical role in the regulation of EMT in cancer, although the underlying mechanism of TAMs-mediated acquisition of EMT has been largely unclear. This review will discuss recent advances in our understanding of the role of TAMs in the regulation of EMT during tumorigenesis and summarize the recent ongoing experimental and pre-clinical TAMs targeted studies.

Modulation of signal transduction pathways by natural compounds in cancer

Cancer is generally regarded as the result of abnormal growth of cells. According to World Health Organization, cancer is the leading cause of mortality worldwide. Mother nature provides a large source of bioactive compounds with excellent therapeutic efficacy. Numerous phytochemicals from nature have been investigated for anticancer properties. In this review article, we discuss several natural compounds, which have shown anti-cancer activity. Natural compounds induce cell cycle arrest, activate intrinsic and extrinsic apoptosis pathways, generate Reactive Oxygen Species (ROS), and down-regulate activated signaling pathways, resulting in inhibition of cell proliferation, progression and metastasis of cancer. Several preclinical studies have suggested that natural compounds can also increase the sensitivity of resistant cancers to available chemotherapy agents. Furthermore, combining FDA approved anti-cancer drugs with natural compounds results in improved efficacy. On the basis of these exciting outcomes of natural compounds against several cancer types, several agents have already advanced to clinical trials. In conclusion, preclinical results and clinical outcomes against cancer suggest promising anticancer efficacy of agents from natural sources.

Synthesis and Evaluation of a Novel Deguelin Derivative, L80, which Disrupts ATP Binding to the C-terminal Domain of Heat Shock Protein 90

The clinical benefit of current anticancer regimens for lung cancer therapy is still limited due to moderate efficacy, drug resistance, and recurrence. Therefore, the development of effective anticancer drugs for first-line therapy and for optimal second-line treatment is necessary. Because the 90-kDa molecular chaperone heat shock protein (Hsp90) contributes to the maturation of numerous mutated or overexpressed oncogenic proteins, targeting Hsp90 may offer an effective anticancer therapy. Here, we investigated antitumor activities and toxicity of a novel deguelin-derived C-terminal Hsp90 inhibitor, designated L80. L80 displayed significant inhibitory effects on the viability, colony formation, angiogenesis-stimulating activity, migration, and invasion of a panel of non-small cell lung cancer cell lines and their sublines with acquired resistance to paclitaxel with minimal toxicity to normal lung epithelial cells, hippocampal cells, vascular endothelial cells, and ocular cells. Biochemical analyses and molecular docking simulation revealed that L80 disrupted Hsp90 function by binding to the C-terminal ATP-binding pocket of Hsp90, leading to the disruption of the interaction between hypoxia-inducible factor (HIF)-1α and Hsp90, downregulation of HIF-1α and its target genes, including vascular endothelial growth factor (VEGF) and insulin-like growth factor 2 (IGF2), and decreased the expression of various Hsp90 client proteins. Consistent with these in vitro findings, L80 exhibited significant antitumor and antiangiogenic activities in H1299 xenograft tumors. These results suggest that L80 represents a novel C-terminal Hsp90 inhibitor with effective anticancer activities with minimal toxicities.

Suppressive function of low-dose deguelin on the invasion of oral cancer cells by downregulating tumor necrosis factor alpha-induced nuclear factor-kappa B signaling

BACKGROUND

Deguelin has both antiproliferation and antimetastasis activities. However, high-dose deguelin elicits many undesired side effects. The purpose of this study was to investigate whether the low-dose deguelin can prevent the metastasis of oral cancer.

METHODS

The dose effects of deguelin on metastasis of oral cancer cells were analyzed by in vitro invasion assay and an orthotropic xenograft mouse model. The involvement of tumor necrosis factor alpha (TNF-α)-induced nuclear factor-kappa B (NF-κB) signaling was examined by Western blot and reporter assay.

RESULTS

Low-dose deguelin, which has minimal cytotoxicity, significantly inhibited the invasion and migration of oral cancer cells. These inhibitory effects of low-dose deguelin were mediated by suppressing TNF-α-induced activation of IκB kinase leading to the inhibition of IκB phosphorylation, NF-κB transcriptional activity, and matrix metalloproteinase-2 (MMP2) expression. The low-dose deguelin treatment significantly inhibited tumor growth and invasion without systemic toxicity.

CONCLUSION

The low-dose deguelin suppressed the invasion and migration of oral cancer by downregulating TNF-α-induced NF-κB signaling. © 2015 Wiley Periodicals, Inc. Head Neck 38: E524-E534, 2016.

The epithelial to mesenchymal transition in pancreatic cancer: A systematic review

BACKGROUND/OBJECTIVES

The present article summarizes and analyzes the current knowledge about the role of the epithelial to mesenchymal transition (EMT) in the systemic invasiveness of pancreatic cancer.

METHOD

An electronic search of PubMed/MEDLINE, EMBASE, and the Web of Science was used to identify relevant original articles and reviews.

RESULTS

The EMT represents a key step during normal embryogenesis. However, increasing evidence reveals its essential role in the local progression and metastasis of pancreatic cancer. Areas of interest are the cross-linking between cells undergoing the EMT and pancreatic cancer stem cells, and the correlation between the EMT and chemoresistance to standard therapies. During carcinogenesis, malignant pancreatic cells at the primary site acquire the ability to undergo the EMT, a transformation associated with increased mobility. The reverse process at secondary sites, the mesenchymal to epithelial transition (MET), has devastating consequences, allowing neoplastic epithelial cells to invade surrounding tissues and spread to distant sites. Consequences of the EMT are the loss of E-cadherin expression and the acquisition of mesenchymal markers including fibronectin or vimentin. Detailed knowledge of the molecular processes underlying the EMT has opened possibilities for new therapeutic agents. These include an EMT approach for patients with early cancers, to prevent invasion and dissemination, and anti-MET therapy for patients with established metastasis.

CONCLUSIONS

The current literature shows a strong correlation between the EMT and the systemic aggressiveness of pancreatic tumors. Individualized therapy, targeting the process of EMT and its cross-linking with cancer stem cells, may increase survival of patients with pancreatic cancer.

STAT3 induces anoikis resistance, promotes cell invasion and metastatic potential in pancreatic cancer cells

Tumor cells need to attain anoikis resistance to survive prior to metastasis making it a vital trait of malignancy. The mechanism by which pancreatic cancer cells resist anoikis and metastasize is not well established. Significant proportion of pancreatic cancer cells resisted anoikis when grown under anchorage-independent conditions. The cells that resisted anoikis showed higher migratory and invasive characteristics than the cells that were cultured under anchorage-dependent condition. Interestingly, anoikis-resistant cells exhibited significantly increased expression and phosphorylation of signal transducer and activation of transcription 3 (STAT3) at Tyr 705, as compared to adherent cells. AG 490 and piplartine (PL) induced significant anoikis in anoikis-resistant pancreatic cancer cells. Silencing STAT3 not only reduced the capacity of pancreatic cancer cells to resist anoikis but also reversed its invasive characteristics. Interleukin-6 treatment and overexpression of STAT3 enhanced anoikis resistance and protected the cells from PL-induced anoikis. PL-treated cells completely failed to develop tumors when injected subcutaneously in immune-compromised mice. Moreover, these cells also failed to metastasize when injected intravenously. On the other hand, untreated anoikis-resistant cells not only formed aggressive tumors but also metastasized substantially to lungs and liver when injected intravenously. Metastatic nodules formed by untreated anoikis-resistant cells in lungs exhibited significant phosphorylation of STAT3 at Tyr705. Taken together, our results established the critical involvement of STAT3 in conferring anoikis resistance to pancreatic cancer cells and increased metastasis.

Deguelin inhibits the migration and invasion of U-2 OS human osteosarcoma cells via the inhibition of matrix metalloproteinase-2/-9 in vitro

Osteosarcoma is the most common malignant primary bone tumor in children and young adults and lung metastasis is the main cause of death in those patients. Deguelin, a naturally occurring rotenoid, is known to be an Akt inhibitor and to exhibit cytotoxic effects, including antiproliferative and anticarcinogenic activities, in several cancers. In the present study, we determined if deguelin would inhibit migration and invasion in U-2 OS human osteosarcoma cells. Deguelin significantly inhibited migration and invasion of U-2 OS human osteosarcoma cells which was associated with a reduction of activities of matrix metalloproteinases-2 (MMP-2) and matrix metalloproteinases-9 (MMP-9). Furthermore, results from western blotting indicated that deguelin decreased the cell proliferation and cell growth-associated protein levels, such as SOS1, PKC, Ras, PI3K, p-AKT(Ser473), IRE-1α, MEKK3, iNOS, COX2, p-ERK1/2, p-JNK1/2, p-p38; the cell motility and focal adhesion-associated protein levels, such as Rho A, FAK, ROCK-1; the invasion-associated protein levels, such as TIMP1, uPA, MMP-2. MMP-9, MMP-13, MMP-1 and VEGF in U-2 OS cells. Confocal microscopy revealed that deguelin reduced NF-κB p65, Rho A and ROCK-1 protein levels in cytosol. MMP-7, MMP-9 and Rho A mRNA levels were suppressed by deguelin. These in vitro results provide evidence that deguelin may have potential as a novel anti-cancer agent for the treatment of osteosarcoma and provides the rationale for in vivo studies in animal models.

Critical role of STAT3 in melanoma metastasis through anoikis resistance

Anoikis is an anchorage-independent cell death. Resistance to anoikis is one of the key features of metastatic cells. Here, we analyzed the role of STAT3 in anoikis resistance in melanoma cells leading to metastasis. When grown under anchorage-independent conditions, significant proportion of cells resisted anoikis and these resistant cells had higher rate of migration and invasion as compared to the cells grown under anchorage-dependent conditions. The anoikis resistant cells also had significantly higher expression and phosphorylation of STAT3 at Y705 than the cells that were attached to the basement membrane. STAT3 inhibitors, AG 490 and piplartine (PL) induced anoikis in a concentration-dependent manner in anoikis resistant cells. Over-expression of STAT3 or treatment with IL-6 not only increased anoikis resistance, but also protected the cancer cells from PL-induced anoikis. On the other hand, silencing STAT3 decreased the potential of cancer cells to resist anoikis and to migrate. STAT3 knock-down cells and PL treated cells did not form tumors as well as failed to metastasize in SCID-NSG mice as compared to untreated anchorage-independent cells, which formed big tumors and extensively metastasized. In summary, our results for the first time establish STAT3 as a critical player that renders anoikis resistance to melanoma cells and enhance their metastatic potential.

Mirabijalone E: a novel rotenoid from Mirabilis himalaica inhibited A549 cell growth in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

The roots of Mirabilis himalaica have been used in Tibetan folk medicine for treatment of uterine cancer, nephritis edematous, renal calculus and arthrodynia. In our previous work, the ethanol extract of roots had shown potent cytotoxicity against human cancer cells. However, no information is available on the antitumor effect of Mirabilis himalaica. The aim of the present study was to investigate the active constituents guided by bioassay and evaluate the related antitumor efficacy in vitro and in vivo.

MATERIALS AND METHODS

The active subextract (ethyl acetate) was subjected to successive chemical separation using a combination of silica gel, LH-20 chromatography and semi-preparative HPLC. The structures were determined by spectroscopic analysis techniques such as nuclear magnetic resonance (NMR) and mass spectrometry. Three human cancer cell lines, A549, HepG2 and HeLa were used for in vitro cytotoxicity evaluation of all isolated compounds by MTT-assay. Then, the potent and novel compound mirabijalone E was employed to the mechanism study againstA549 cells. BrdU immunofluorescence, soft agar assay and cell cycle analysis were employed to detect the cell proliferation effects. Annexin V-FITC/PI staining assay was used for examining apoptotic effects. Expression levels of apoptosis-related proteins were determined by western blot assay. in vivo tumorigenic assay was used to evaluate the xenograft tumor growth treated with mirabijalone E.

RESULTS

One new rotenoid compound, mirabijalone E, together with eight known rotenoids was isolated from Mirabilis himalaica. Mirabijalone E, 9-O-methyl-inone B, boeravinone C and boeravinone H exhibited cytotoxicity against A 549 and HeLa cells. Further study on mirabijalone E was carried out in vitro and in vivo. Mirabijalone E inhibited A549 cells growth in a time and dose-dependent manner, which arrested cell cycle in S phase. Mechanistically, mirabijalone E treatment resulted in the increase of Bax expression level, the decrease of Bcl-2 level and the activation of caspase-3, which suggested the activation of apoptosis cascades. Consequently, the xenograft treated with mirabijalone E showed markedly suppressed tumor growth.

CONCLUSIONS

The result suggested that mirabijalone E, together with active compounds, 9-O-methyl-4-hydroxyboeravinone B, boeravinone C and boeravinone H could be a promising candidate for cancer therapy.