Cytotoxic Impact of Costunolide Isolated from Costus speciosus on Breast Cancer via Differential Regulation of Cell Cycle—An In‐vitro and In‐silico Approach

Costunolide, a sesquiterpene lactone, is a biologically active molecule found in most of the medicinally valuable plants. The present study aims to evaluate the anticancer property of costunolide isolated from Costus speciosus against breast cancer cell lines (MCF‐7 and MDA‐MB‐231). Costunolide effectively reduced the viability of both MCF‐7 and MDA‐MB‐231 cell lines at an IC₅₀ value of 40 μM. Flow cytometric analysis revealed costunolide mediated cell cycle arrest at G2/M phase in both the cell types. Western blotting results confirmed the alterations in the expression of cell cycle regulators (cyclin D1, D3, CDK‐4, CDK‐6, p18 INK4c, p21 CIP1/Waf‐1 and p27 KIP1) and apoptosis inducers (caspase‐3 and caspase‐9) upon costunolide treatment in comparison with their expressions in normal breast cell line (MCF‐10A). Costunolide mediated downregulation of positive cell cycle regulators and upregulation of negative cell cycle regulators were related to the induction of apoptosis in cancer cells. The above results were validated with in‐silico results that predicted stable interactions between costunolide and cancer targets. Thus costunolide effectively induced breast cancer cell apoptosis targeting cell cycle regulation, and the compound can be used as an effective herbal therapeutic molecule to treat breast cancer with further explorations. Copyright © 2015 John Wiley & Sons, Ltd.     

Norstictic Acid Inhibits Breast Cancer Cell Proliferation,Migration, Invasion,and In Vivo Invasive Growth Through Targeting C‐Met

Breast cancer is a major health problem affecting the female population worldwide. The triple‐negative breast cancers (TNBCs) are characterized by malignant phenotypes, worse patient outcomes, poorest prognosis, and highest mortality rates. The proto‐oncogenic receptor tyrosine kinase c‐Met is usually dysregulated in TNBCs, contributing to their oncogenesis, tumor progression, and aggressive cellular invasiveness that is strongly linked to tumor metastasis. Therefore, c‐Met is proposed as a promising candidate target for the control of TNBCs. Lichens‐derived metabolites are characterized by their structural diversity, complexity, and novelty. The chemical space of lichen‐derived metabolites has been extensively investigated, albeit their biological space is still not fully explored. The anticancer‐guided fractionation of Usnea strigosa (Ach.) lichen extract led to the identification of the depsidone‐derived norstictic acid as a novel bioactive hit against breast cancer cell lines. Norstictic acid significantly suppressed the TNBC MDA‐MB‐231 cell proliferation, migration, and invasion, with minimal toxicity to non‐tumorigenic MCF‐10A mammary epithelial cells. Molecular modeling, Z'‐LYTE biochemical kinase assay and Western blot analysis identified c‐Met as a potential macromolecular target. Norstictic acid treatment significantly suppressed MDA‐MB‐231/GFP tumor growth of a breast cancer xenograft model in athymic nude mice. Lichen‐derived natural products are promising resources to discover novel c‐Met inhibitors useful to control TNBCs. Copyright © 2016 John Wiley & Sons, Ltd.     

Ramalin‐Mediated Apoptosis Is Enhanced by Autophagy Inhibition in Human Breast Cancer Cells

Breast cancer, the most commonly diagnosed cancer in women worldwide, is treated in various ways. Ramalin is a chemical compound derived from the Antarctic lichen Ramalina terebrata and is known to exhibit antioxidant and antiinflammatory activities. However, its effect on breast cancer cells remains unknown. We examined the ability of ramalin to induce apoptosis and its mechanisms in MCF‐7 and MDA‐MB‐231 human breast cancer cell lines. Ramalin inhibited cell growth and induced apoptosis in both cell lines in a concentration‐dependent manner. By upregulating Bax and downregulating Bcl‐2, ramalin caused cytochrome c and apoptosis‐inducing factor to be released from the mitochondria into the cytosol, thus activating the mitochondrial apoptotic pathway. In addition, activated caspase‐8 and caspase‐9 were detected in both types of cells exposed to ramalin, whereas ramalin activated caspase‐3 only in the MDA‐MB‐231 cells. Ramalin treatment also increased the levels of LC3‐II and p62. Moreover, the inhibition of autophagy by 3‐methyladenine or Atg5 siRNA significantly enhanced ramalin‐induced apoptosis, which was accompanied by a decrease in Bcl‐2 levels and an increase in Bax levels. Therefore, autophagy appears to be activated as a protective mechanism against apoptosis in cancer cells exposed to ramalin. These findings suggest that ramalin is a potential anticancer agent for the treatment of patients with non‐invasive or invasive breast cancer. Copyright © 2015 John Wiley & Sons, Ltd.     

Antiproliferative alkaloids from Crinum zeylanicum

Crinum zeylanicum is used in folk medicine as a rubefacient in rheumatism, a treatment for malaria or as a poison. Complex alkaloid profiles in C. zeylanicum plant organs were revealed by GC‐MS analysis, including several bioactive compounds. Crinine, lycorine, 11‐O‐acetoxyambelline, ambelline, 6‐hydroxybuphanidrine and 6‐ethoxybuphanidrine (an artefact of the isolation procedure) were isolated. Crinine, 6‐hydroxybuphanidrine and 6‐ethoxybuphanidrine showed antiproliferative effects against human tumor cell lines, crinine being the most active (IC₅₀ 14.04 μm against HL‐60/Dox). The latter compound induced apoptosis in a dose‐dependent manner in HL‐60 and MDA‐MB‐231 cell lines. Structure‐activity relationships in the studied molecules indicated that the hydrogenation of the double bond at C1‐C2 leads to a loss of activity, whereas substitutions at C6, C8 and C11 affect their cytotoxicity. Copyright © 2011 John Wiley & Sons, Ltd.     

Cytotoxic Properties of the Stem Bark of Citrus reticulata Blanco (Rutaceae)

The bioassay‐guided fractionation of the n‐hexane extract of Citrus reticulata Blanco (Rutaceae) stem bark yielded scoparone (1), xanthyletin (2), lupeol (3), β‐amyrin (4), stigmasterol (5), β‐sitosterol (6) and palmitic acid. The structures of these compounds were determined by comprehensive spectroscopic analyses, i.e., 1D and 2D NMR and EI‐MS, and by comparison with the reported data. Extracts, fractions and isolated compounds 1–6 were assessed for cytotoxicity by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐dphenyltetrazolium bromide (MTT) assay against three human cancer cell lines, i.e., human lung adenocarcinoma cell line A549, human breast adenocarcinoma cell line MCF7 and human Caucasian prostate adenocarcinoma cell line PC3. Significant activity of the n‐hexane and the dichloromethane extracts was observed against the breast cancer cell line MCF7 with IC₅₀s of 45.6 and 54.7 μg/mL, respectively. Moreover, the 70% ethyl acetate in n‐hexane chromatographic fraction showed significant activity displaying IC₅₀ values of 53.0, 52.4 and 49.1 μg/mL against the cancer cell lines A549, MCF7 and PC3, respectively. Encouragingly, an IC₅₀ of 510.0 μg/mL against the human normal prostate cell line PNT2 indicated very low toxicity and hence favourable selectivity indices for the 70% ethyl acetate in n‐hexane fraction in the range of 9.6–10.4 towards cell lines A549, MCF7 and PC3. Because compounds isolated from the above fraction only delivered IC₅₀ values in the range of 18.2–96.3, 9.2–34.1 and 7.5–97.2 μg/mL against A549, MCF7 and PC3 cell lines, respectively, synergistic action between compounds is suggested. Bioassay results valorize the anticancer effectivity of the stem bark of this plant in Cameroonian pharmacopoeia. Copyright © 2017 John Wiley & Sons, Ltd.     

Anticancer activity and molecular mechanisms of α‐conidendrin,a polyphenolic compound present in Taxus yunnanensis,on human breast cancer cell lines

α‐Conidendrin is a polyphenolic compound found mainly in Taxus yunnanensis, as the source of chemotherapy drug paclitaxel, which has been used in traditional medicine for treatment of cancer. This study aimed to investigate the anticancer activity and molecular mechanisms of α‐conidendrin on breast cancer cell lines. The results of the present study show that α‐conidendrin possesses potent antiproliferative effects on breast cancer cell lines MCF‐7 and MDA‐MB‐231. α‐Conidendrin significantly induced apoptosis in breast cancer cells via reactive oxygen species generation, upregulation of p53 and Bax, downregulation of Bcl‐2, depolarization of mitochondrial membrane potential (MMP), release of cytochrome c from mitochondria, and activation of caspases‐3 and ‐9. α‐Conidendrin remarkably inhibited the proliferation of breast cancer cells through induction of cell cycle arrest by upregulating p53 and p21 and downregulating cyclin D1 and CDK4. Unlike breast cancer cells, the antiproliferative effect of α‐conidendrin on human foreskin fibroblast cells (normal cells) was very small. In normal cells, reactive oxygen species levels, loss of MMP, release of cytochrome c, mRNA expression of p53, p21, cyclin D1, CDK4, Bax, and Bcl‐2 as well as mRNA expression and activity of caspases‐3 and ‐9 were significantly less affected by α‐conidendrin compared with cancer cells. These results suggest that α‐conidendrin can be a promising agent for treatment of breast cancer with little or no toxicity against normal cells.     

Rutin,a Quercetin Glycoside,Restores Chemosensitivity in Human Breast Cancer Cells

Several studies have documented the ability of flavonoids to sensitize cancer cells to chemotherapeutics and reverse multidrug resistance by inhibition of efflux pumps (adenosine triphosphate‐binding cassette transporters), apoptosis activation, and cell cycle arrest. In this study, the flavonoid rutin (quercetin 3‐O‐β‐d ‐rutinoside) was investigated as chemosensitizer towards two different human epithelial breast cancer cell lines: (i) MB‐MDA‐231, selected as representative for triple‐negative breast cancer and (ii) MCF‐7 used as a well‐characterized model of HER2‐negative breast cancer. To assess the cytocompatibility of rutin against non‐cancer cells, primary human mammary fibroblasts were used as control and non‐target cells. In MDA‐MB‐231 cells, 20 μM rutin enhanced cytotoxicity related to cyclophosphamide and methotrexate. Rutin significantly (p < 0.05) increased the anticancer activity of both chemotherapeutics, at 24–48–72 h, and decreased the activity of the adenosine triphosphate‐binding cassette transporters, namely, P‐glycoprotein (P‐gp) and breast cancer resistance protein (BCRP). Flow cytometry analysis showed 20 μM and 50 μM rutin arrested cell cycle at G2/M and G0/G1 phases, respectively, significantly promoting cell apoptosis. Rutin, via non‐selective inhibition of P‐gp and BCRP pumps, efficiently reverses multidrug resistance and restores chemosensitivity to cyclophosphamide and cyclophosphamide of human chemoresistant, triple‐negative breast cancer cells, successfully arresting cell cycle progression. Copyright © 2017 John Wiley & Sons, Ltd.     

In vitro anti-prostate cancer and ex vivo antiangiogenic activity of Vernonia guineensis Benth. (Asteraceae) tuber extracts

Ethnopharmacological relevance

Prostate cancer is a major problem worldwide and affects most men above the age of forty-five. Vernonia guineensis Benth. (Asteraceae) root decoction is used in folk medicine in Cameroon to treat a number of ailments including prostate cancer. The aim of this study was to provide a preliminary validation of the use of Vernonia guineensis Benth. extracts to treat prostate cancer by evaluating the in vitro activity of its crude extracts and isolated molecules on prostate cancer cells lines and effect on angiogenesis which is essential for growth and metastases of prostate cancer.

Materials and methods

Aqueous, dichloromethane and methanol extracts of Vernonia guineensis Benth. tubers were tested for activity against three prostate cancer cell lines (PC-3, DU-145 and AT3B-1). The dichloromethane extract was subjected to bioactivity guided fractionation. Anti-proliferation, clonogenic and antiangiogenic activity of the crude extracts and isolated compound were tested. The WST-1 assay was used for the anti-proliferation activity meanwhile the standard clonogenic test and the rat ring aorta assay were carried out to determine the clonogenic and antiangiogenic activity of tested products respectively.

Results

The aqueous and methanol extracts of Vernonia guineensis Benth. demonstrated weak activity against prostate cancer cell lines in vitro with IC₅₀ > 100 μg/mL. The dichloromethane extract was more potent with IC₅₀ of 56.233 ± 3.630 μg/ml and 67.316 ± 2.452 μg/ml against the DU-145 and PC-3 cell lines respectively. Activity guided fractionation of this extract yielded a Pentaisovalerylsucrose (1) isolated for the first time from a natural source to the best of our knowledge. Compound 1 demonstrated in vitro activity against the human prostate cancer cell lines PC-3 and DU-145 with IC₅₀ of 5.701 ± 0.142 μM and 4.275 ± 0.710 μM, respectively. The IC₅₀ of the compound was 5.763 ± 0.425 μM against AT3B-1, a rat prostate cancer cell line expressing P-glycoprotein which is linked to drug resistance in most metastatic cancers. Compared to compound 1, Paclitaxel and Docetaxel were active against AT3B-1 at 2.641 ± 1.253 μM and 0.613 ± 0.251 μM. Paclitaxel showed IC₅₀ values of 0.004 ± 0.002 μM and 0.003 ± 0.001 μM against DU-145 and PC-3 prostate cancer cell lines respectively. Docetaxel showed IC₅₀ values of 0.002 ± 0.001 μM and 0.004 ± 0.001 μM against DU-145 and PC-3 prostate cancer cell lines respectively.

Conclusion

The in vitro anti-prostate cancer and the antiangiogenic activity of Vernonia guineensis Benth. extracts and isolated compound support the use of the tubers of this plant for the treatment of prostate cancer.     

Zanthoxylum usambarense (Engl.) Kokwaro (Rutaceae) Extracts Inhibit the Growth of the Breast Cancer Cell Lines MDA‐MB‐231 and MCF‐7, But Not the Brain Tumour Cell Line U251 In Vitro

Zanthoxylum usambarense (Engl.) Kokwaro has traditionally been used for the treatment of malaria, upper respiratory tract infections, cough, rheumatism, tooth decay and sore gums in Kenya and other African countries. Dried ground parts of Z. usambarense were extracted by maceration using methanol (MeOH) at room temperature, extract was dried and reconstituted in 70% aq. MeOH and partitioned against n‐hexane and chloroform (CHCl₃) to obtain MeOH, n‐hexane and CHCl₃ extracts. All extracts were assessed for cytotoxicity against two breast cancer cell lines, MDA‐MB‐231 and MCF‐7, and the brain tumour cell line U251 by the MTT assay. The free‐radical scavenging activity of the extracts was also determined by the 2,2‐diphenyl‐1‐picryhydrazyl (DPPH) assay. In the DPPH assay, the MeOH extract was found to be the most active free‐radical scavenger with a RC₅₀ value of 41.1 × 10^?3 mg/mL. It also displayed significant cytotoxicity against the MCF‐7 cell line (IC₅₀ 42.9 µg/mL) and appeared to have induced cell death through apoptosis. None of the test extracts showed any activity against the U251 cell line at test concentrations. The present findings demonstrated that Z. usambarense could be a potential source for new cytotoxic compounds for possible anticancer drug development. Copyright © 2012 John Wiley & Sons, Ltd.     

Polyphenols from Artemisia annua L Inhibit Adhesion and EMT of Highly Metastatic Breast Cancer Cells MDA‐MB‐231

Recent evidence suggests that polyphenolic compounds from plants have anti‐invasion and anti‐metastasis capabilities. The Korean annual weed, Artemisia annua L., has been used as a folk medicine for treatment of various diseases. Here, we isolated and characterized polyphenols from Korean A. annua L (pKAL). We investigated anti‐metastatic effects of pKAL on the highly metastatic MDA‐MB‐231 breast cancer cells especially focusing on cancer cell adhesion to the endothelial cell and epithelial‐mesenchymal transition (EMT). Firstly, pKAL inhibited cell viability of MDA‐MB‐231 cells in a dose‐dependent manner, but not that of human umbilical vein endothelial cells (ECs). Polyphenols from Korean A. annua L inhibited the adhesion of MDA‐MB‐231 cells to ECs through reducing vascular cell adhesion molecule‐1 expression of MDA‐MB‐231 and ECs, but not intracellular adhesion molecule‐1 at the concentrations where pKAL did not influence the cell viability of either MDA‐MB‐231 cells nor EC. Further, pKAL inhibited tumor necrosis factor‐activated MDA‐MB‐231 breast cancer cell invasion through inhibition of matrix metalloproteinase‐2 and matrix metalloproteinase‐9 and EMT. Moreover, pKAL inhibited phosphorylation of Akt, but not that of protein kinase C. These results suggest that pKAL may serve as a therapeutic agent against cancer metastasis at least in part by inhibiting the cancer cell adhesion to ECs through suppression of vascular cell adhesion molecule‐1 and invasion through suppression of EMT. Copyright © 2016 John Wiley & Sons, Ltd.     

Growth inhibitory activity of biflavonoids and diterpenoids from the leaves of the Libyan Juniperus phoenicea against human cancer cells

Three biflavonoids [cupressuflavone ( 1 ), amentoflavone ( 2 ), and sumaflavone ( 3 )], four diterpenoids [13‐epi‐cupressic acid ( 4 ), imbricatholic acid ( 5 ), 3‐hydroxy‐sandaracopimaric acid ( 6 ), and dehydroabietic acid ( 7 )], and one lignan [β‐peltatin methyl ether ( 8 )] were isolated from the cytotoxic fractions of the extracts of the leaves of the Libyan Juniperus phoenicea L. The structures of these compounds were elucidated by spectroscopic means. Cytotoxicity of compounds 1 – 6 were assessed against the human lung cancer cell line A549 using the MTT assay. Compounds 1 and 3 showed cytotoxicity against the A549 cells (IC₅₀ = 65 and 77 μM, respectively), whereas compound 2 did not show any activity. Diterpenes 4 – 6 exhibited weak cytotoxicity against the A549 cells with the IC₅₀ values of 159, 263, and 223 μM, respectively. The cytotoxicity of each compound was compared with the anticancer drug, etoposide (IC₅₀ = 61 μM). Cupressuflavone ( 1 ) was evaluated also for cytotoxicity against both the human PC3 cancer cell line and the normal prostate cell line (PNT2), and this compound revealed a high degree of cytotoxic selectivity towards the prostate cancer cells (PC3), with IC₅₀ value of 19.9 μM, without any evidence of cytotoxicity towards the normal prostate cell line (PNT2).     

The Antioxidant and Anticancer Effects of Wild Carrot Oil Extract

Daucus carota L. ssp. carota (Apiacea) is used in traditional medicine in Lebanon and in different regions throughout the world. The present study investigates the in vitro anticancer activities of Daucus carota oil extract (DCOE) on four human cancer cell lines as well as its in vitro antioxidant activity. DCOE was extracted from the dried umbels with 50:50 acetone‐methanol. The oil extract was analyzed by gas chromatography–mass spectrometry and screened for its antioxidant properties in vitro using 1,1‐diphenyl‐2‐picryl hydrazyl free radical scavenging assay (DPPH), ferrous ion chelating assay (FIC) and the ferric reducing antioxidant power assay (FRAP). The anticancer activity of the oil extract against human colon (HT‐29, Caco‐2) and breast (MCF‐7, MDA‐MB‐231) cancer cell lines was evaluated using the trypan blue exclusion method and the WST‐1 cell proliferation assay. DCOE exhibited antioxidant activity in all assays used. The FRAP value was 164 ± 5.5 µmol FeSO₄/g, and the IC₅₀ values for DPPH and FIC assays were 2.1 ± 0.03 mg/ml and 0.43 ± 0.02 mg/ml, respectively. Also, DCOE demonstrated a significant increase in cell death and decrease in cell proliferation. The effect of DCOE on the cell lines exhibited time and dose‐dependent responses. The present study established that DCOE possesses both antioxidant and promising anticancer activities. Copyright © 2012 John Wiley & Sons, Ltd.     

Olive Oil‐derived Oleocanthal as Potent Inhibitor of Mammalian Target of Rapamycin: Biological Evaluation and Molecular Modeling Studies

The established anticancer and neuroprotective properties of oleocanthal combined with the reported role of mammalian target of rapamycin (mTOR) in cancer and Alzheimer's disease development encouraged us to examine the possibility that oleocanthal inhibits mTOR. To validate this hypothesis, we docked oleocanthal into the adenosine triphosphate binding pocket of a close mTOR protein homologue, namely, PI3K‐γ. Apparently, oleocanthal shared nine out of ten critical binding interactions with a potent dual PIK3‐γ/mTOR natural inhibitor. Subsequent experimental validation indicated that oleocanthal indeed inhibited the enzymatic activity of mTOR with an IC₅₀ value of 708 nM. Oleocanthal inhibits the growth of several breast cancer cell lines at low micromolar concentration in a dose‐dependent manner. Oleocanthal treatment caused a marked downregulation of phosphorylated mTOR in metastatic breast cancer cell line (MDA‐MB‐231). These results strongly indicate that mTOR inhibition is at least one of the factors of the reported anticancer and neuroprotective properties of oleocanthal. Copyright © 2015 John Wiley & Sons, Ltd.     

Antitumour effects of phyllanthus emblica L.: Induction of cancer cell apoptosis and Inhibition of in vivo tumour promotion and in vitro invasion of human cancer cells

Phyllanthus emblica Linn. (PE) is a medicinal fruit used in many Asian traditional medicine systems for the treatment of various diseases including cancer. The present study tested the potential anticancer effects of aqueous extract of PE in four ways: (1) against cancer cell lines, (2) in vitro apoptosis, (3) mouse skin tumourigenesis and (4) in vitro invasiveness. The PE extract at 50–100 µg/mL significantly inhibited cell growth of six human cancer cell lines, A549 (lung), HepG2 (liver), HeLa (cervical), MDA‐MB‐231 (breast), SK‐OV3 (ovarian) and SW620 (colorectal). However, the extract was not toxic against MRC5 (normal lung fibroblast). Apoptosis in HeLa cells was also observed as PE extract caused DNA fragmentation and increased activity of caspase‐3/7 and caspase‐8, but not caspase‐9, and up‐regulation of the Fas protein indicating a death receptor‐mediated mechanism of apoptosis. Treatment of PE extract on mouse skin resulted in over 50% reduction of tumour numbers and volumes in animals treated with DMBA/TPA. Lastly, 25 and 50 µg/mL of PE extract inhibited invasiveness of MDA‐MB‐231 cells in the in vitro Matrigel invasion assay. These results suggest P. emblica exhibits anticancer activity against selected cancer cells, and warrants further study as a possible chemopreventive and antiinvasive agent. Copyright © 2010 John Wiley & Sons, Ltd.     

Trametenolic Acid B Reverses Multidrug Resistance in Breast Cancer Cells Through Regulating the Expression Level of P‐Glycoprotein

Trametenolic acid B (TAB) is the main active composition of Trametes lactinea (Berk.) Pat which possesses anti‐tumor activities. There was no report its antitumor effect through regulating P‐glycoprotein (P‐gp) so far, due to P‐gp over expression is one of the most important mechanisms contributing to the multiple drug resistance phenotype. The present aim was to investigate the effects of TAB on P‐gp in multidrug‐resistant cells; Paclitaxel‐resistant cell line MDA‐MB‐231/Taxol was established by stepwise exposure for 10 months. MDA‐MB‐231 cells and MDA‐MB‐231/Taxol cells were treated with TAB, and their growth was evaluated using MTT assays. Paclitaxel accumulation in the cells was analyzed by high performance liquid chromatogram (HPLC). The activity of P‐gp was detected by intracellular accumulation of rhodamine123 (Rho123), and the protein expression of P‐gp was evaluated using western blot. Results indicated that the IC₅₀ of MDA‐MB‐231/Taxol to paclitaxel (Taxol) was 33 times higher than that of nature MDA‐MB‐231. TAB increased the intracellular concentration of Taxol and inhibited the activity of P‐gp and suppressed the expression of P‐gp in MDA‐MB‐231/Taxol cells. Our present results showed that TAB could reverse Taxol resistance in MDA‐MB‐231/Taxol cells, mainly inhibiting the activity of P‐gp and down‐regulating the expression level of P‐gp, and then enhancing the accumulation of chemotherapy agents. © 2013 The Authors Phytotherapy Research Published by John Wiley & Sons Ltd.     

Apoptotic effect of lambertianic acid through AMPK/FOXM1 signaling in MDA‐MB231 breast cancer cells

Though lambertianic acid (LA) was known to exert antitumor effect in liver and prostate cancers, its underlying anticancer mechanism is never reported in breast cancers so far. Thus, in this study, apoptotic mechanism of LA was elucidated in MDA‐MB‐231 breast cancer cells. Here, LA increased cytotoxicity in MCF‐7 and MDA‐MB‐231 cells; enhanced sub‐G1 population, G2/M arrest, and cleaved poly(ADP‐ribose) polymerase; activated phosphorylation of AMP‐activated protein kinase (AMPK)/acetyl‐CoA carboxylase pathway; and also suppressed phosphorylation of AKT and the expression of forkhead box M1 (FOXM1), X‐linked inhibitor of apoptosis protein, B‐cell lymphoma 2, and CyclinB1 in MDA‐MB‐231 cells. Furthermore, AMPK inhibitor compound C reversed the effect of LA on FOXM1, Cyclin B1, and cleaved poly(ADP‐ribose) polymerase in MDA‐MB‐231 cells. Notably, immunoprecipitation revealed that LA disturbed the direct binding of AKT and FOXM1 in MDA‐MB‐231 cells. Overall, these findings suggest that LA‐induced apoptosis is mediated via activation of AMPK and inhibition of AKT/FOXM1 signaling pathway.     

Withanolide sulfoxide from Aswagandha roots inhibits nuclear transcription factor‐kappa‐B,cyclooxygenase and tumor cell proliferation

Investigation of the methanol extract of Aswagandha (Withania somnifera) roots for bioactive constituents yielded a novel withanolide sulfoxide compound (1) along with a known withanolide dimer ashwagandhanolide (2) with an S‐linkage. The structure of compound 1 was established by extensive NMR and MS experiments. Compound 1 was highly selective in inhibiting cyclooxygenase‐2 (COX‐2) enzyme by 60% at 100 µm with no activity against COX‐1 enzyme. The IC₅₀ values of compound 1 against human gastric (AGS), breast (MCF‐7), central nervous system (SF‐268) and colon (HCT‐116) cancer cell lines were in the range 0.74–3.63 µm. Both S‐containing dimeric withanolides, 1 and 2, completely suppressed TNF‐induced NF‐κB activation when tested at 100 µm. The isolation of a withanolide sulfoxide from W. somnifera roots and its ability to inhibit COX‐2 enzyme and to suppress human tumor cell proliferation are reported here for the first time. In addition, this is the first report on the abrogation of TNF‐induced NF‐κB activation for compounds 1 and 2. Copyright © 2009 John Wiley & Sons, Ltd.     

Theacrine attenuates epithelial mesenchymal transition in human breast cancer MDA‐MB‐231 cells

Theacrine, a purine alkaloid structurally similar to caffeine, has recently become of interest as a potential therapeutic compound. Here, we investigated the antimetastatic potential of theacrine on human breast cancer MDA‐MB‐231 cells. We observed that theacrine can reverse epithelial‐to‐mesenchymal transition (EMT), which resulted in a decrease in the levels of mesenchymal markers (Fibronectin, Vimentin, N‐cadherin, Twist, and Snail) and an increase in the levels of epithelial markers (Occludin and E‐cadherin) in the cells. Additionally, theacrine attenuates TGF‐β‐induced EMT, cell adhesion, migration, and invasion in MDA‐MB‐231 cells. Overall, our results suggest that theacrine may inhibit the breast cancer cell metastasis by reversing the EMT process.