Photodynamic treatment increases the lifespan and oxidative stress resistance of Caenorhabditis elegans.

Photodynamic therapy is a noninvasive treatment in which specific photosensitizers and light are used to produce high amounts of reactive oxygen species (ROS), which can be employed for targeted tissue destruction in cancer treatment or antimicrobial therapy. However, it remains unknown whether lower amounts of ROS produced by mild photodynamic therapy increase lifespan and stress resistance at the organism level. Here, we introduce a novel photodynamic treatment (PDTr) that uses 20 µM hypericin, a photosensitizer that originates from Hypericum perforatum, and orange light (590 nm, 5.4 W/m2, 1 min) to induce intracellular ROS formation (ROS), thereby resulting in lifespan extension and improved stress resistance in C. elegans. The PDTr-induced increase in longevity was abrogated by N-acetyl cysteine, suggesting the hormetic response was driven by prooxidative mechanisms. PDTr activated the translocation of SKN-1/NRF-2 and DAF-16/FOXO, leading to elevated expression of downstream oxidative stress-responsive genes, including ctl-1, gst-4, and sod-3. In summary, our findings suggest a novel PDTr method that extends the lifespan of C. elegans under both normal and oxidative stress conditions through the activation of SKN-1 and DAF-16 via the involvement of many antioxidant genes.

Tropolone-Bearing Sesquiterpenes from Juniperus chinensis: Structures, Photochemistry and Bioactivity.

The tropolone-bearing sesquiterpenes juniperone A (1) and norjuniperone A (2) were isolated from the folk medicinal plant Juniperus chinensis, and their structures were determined by a combination of spectroscopic and crystallographic methods. Photojuniperones A1 (3) and A2 (4), bearing bicyclo[3,2,0]heptadienones derived from tropolone, were photochemically produced and structurally identified by spectroscopic methods. Predicted by the machine learning-based assay, 1 significantly inhibited the action of tyrosinase. The new compounds also inhibited lipid accumulation and enhanced the extracellular glycerol excretion.

High-throughput and direct measurement of androgen levels using turbulent flow chromatography liquid chromatography-triple quadrupole mass spectrometry (TFC-LC-TQMS) to discover chemicals that modulate dihydrotestosterone production in human prostate cancer cells.

OBJECTIVES: To develop a high-throughput screening system to measure the conversion of testosterone to dihydrotestosterone (DHT) in cultured human prostate cancer cells using turbulent flow chromatography liquid chromatography-triple quadrupole mass spectrometry (TFC-LC-TQMS). RESULTS: After optimizing the cell reaction system, this method demonstrated a screening capability of 103 samples, including 78 single compounds and 25 extracts, in less than 12 h without manual sample preparation. Consequently, fucoxanthin, phenethyl caffeate, and Curcuma longa L. extract were validated as bioactive chemicals that inhibited DHT production in cultured DU145 cells. In addition, naringenin boosted DHT production in DU145 cells. CONCLUSION: The method can facilitate the discovery of bioactive chemicals that modulate the DHT production, and four phytochemicals are potential candidates of nutraceuticals to adjust DHT levels in male hormonal dysfunction.

Measuring the Effect of Chemicals on the Growth and Reproduction of Caenorhabditis elegans.

Toxicological evaluation is crucial for understanding the effects of chemicals on living organisms in basic and applied biological science fields. A non-mammalian soil round worm, Caenorhabditis elegans, is a valuable model organism for toxicology studies due to its convenience and lack of animal ethics issues compared with mammalian animal systems. In this protocol, a detailed procedure of toxicological evaluation of chemicals in C. elegans is described. A clinical anticancer drug, etoposide, which targets human topoisomerase II and inhibits DNA replication of human cancer cells, was selected as a model testing chemical. Age-synchronized C. elegans eggs were exposed to either dimethyl sulfoxide (DMSO) or etoposide, and then the growth of C. elegans was monitored every day for 4 days by the stereo microscope observation. The total number of eggs laid from C. elegans treated with DMSO or etoposide was also counted by using the stereo microscope. Etoposide treatment significantly affected the growth and reproduction of C. elegans. By comparison of the total number of eggs laid from worms with different treatment periods of chemicals, it can be decided that the reproductive toxicity of chemicals on C. elegans reproduction is reversible or irreversible. These protocols may be helpful for both the development of various drugs and risk assessment of environmental toxicants.

Data on the anti-tumor effects of Selaginella tamariscina extract and amentoflavone combined with doxorubicin in mice.

Here, we report animal experimental data associated with the article entitled "AKR1B10-inhibitory Selaginella tamariscina extract and amentoflavone decrease the growth of A549 human lung cancer cells in vitro and in vivo" (Jung et al., 2017) [1]. We tested the synergistic anti-tumor effects of Selaginella tamariscina extract and amentoflavone combined with doxorubicin hydrochloride in a nude mouse xenograft model of A549 human lung cancer cells. In our experiment, Selaginella tamariscina extract and amentoflavone were administered orally; and doxorubicin hydrochloride was injected intraperitoneally. We expect our preliminary data will be helpful to the development of the anticancer agent using Selaginella tamariscina extract or amentoflavone.

AKR1B10-inhibitory Selaginella tamariscina extract and amentoflavone decrease the growth of A549 human lung cancer cells in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: Selaginella tamariscina (P.Beauv.) Spring is a traditional medicinal plant used to treat various human diseases, including cancer, in Asia. The detailed molecular mechanism underlying the anti-cancer effects of this plant and the anti-cancer action of the combinatorial treatment of S. tamariscina and doxorubicin have not yet been investigated. AIM OF THE STUDY: We evaluated the inhibitory activity of S. tamariscina extract (STE) and its major compound, amentoflavone, on human aldo-keto reductase family 1B10 (AKR1B10), which is a detoxification enzyme involved in drug resistance, to evaluate their anti-cancer effects and their potential as adjuvant agents for doxorubicin cancer chemotherapy. MATERIALS AND METHODS: We tested the AKR1B10 inhibitory activity of STE and amentoflavone via an in vitro biochemical assay using recombinant human AKR1B10. We tested the anti-proliferative activity in A549, NCI-H460, SKOV-3, and MCF-7 human cancer cells, which contain different expression levels of AKR1B10, and determined the combination index to evaluate whether the addition of STE and amentoflavone is synergistic or antagonistic to the anti-cancer action of doxorubicin. We finally evaluated the in vivo anti-tumor effects of STE in a nude mouse xenograft model of A549 cells. RESULTS: STE and amentoflavone potently inhibited human AKR1B10 and synergistically increased the doxorubicin anti-proliferative effect in A549 and NCI-H460 human lung cancer cells that express a high level of AKR1B10 mRNA and protein. STE also significantly inhibited A549 tumor growth in animal experiments. CONCLUSION: Our results suggest that STE and amentoflavone could be potential anti-cancer agents that target AKR1B10 and might be candidate adjuvant agents to boost the anti-cancer effect of doxorubicin.

Toxicological evaluation of the topoisomerase inhibitor, etoposide, in the model animal Caenorhabditis elegans and 3T3-L1 normal murine cells.

Etoposide, a topoisomerase II inhibitor, has been widely used as a clinical anticancer drug to treat diverse cancer patients. Since not only rapidly dividing cancer cells but also the cells of normal human tissues and every living organism in environmental ecosystems have topoisomerases, it is crucial to study the toxicity of etoposide in other organisms in addition to cancer cells. In this study, we evaluated the toxicity of etoposide in both a soil nematode, Caenorhabditis elegans, and 3T3-L1 normal murine cells. Etoposide significantly retarded the growth, egg laying, and hatching in C. elegans. Etoposide also affected the reproductive gonad tissue, decreased the number of germ cells and induced abnormally enlarged nuclei in C. elegans. In addition, etoposide inhibited 3T3-L1 cell proliferation, with IC50 values of 37.8 ± 7.3 and 9.8 ± 1.8 µM after 24 and 48 hours of treatment, respectively, via the induction of cell cycle arrest at the G2/M phase and apoptotic cell death. Etoposide also induced nuclear enlargement in 3T3-L1 normal murine cells. The reproductive toxicity and abnormal nuclear morphological changes seemed to correlate with the adverse effects of etoposide. We suggest that these experimental platforms, i.e., the toxicological evaluation of both nematodes and 3T3-L1 cells, may be useful to study the mechanisms underlying the side effects of chemicals, including topoisomerase inhibitors.

Isolation of major phenolics from Launaea spinosa and their protective effect on HepG2 cells damaged with t-BHP.

CONTEXT: Some Launaea species (Asteraceae) are used traditionally to treat liver oxidative stress. OBJECTIVE: The present study investigates the protective effects of isolated compounds from Launaea spinosa Sch. Bip. (Asteraceae) against oxidative stress on t-BHP-induced HepG2 cells. MATERIALS AND METHODS: Major phenolic content from flowering aerial parts of L. spinosa was isolated and identified. The protective effects of isolated compounds (10 and 20 µM) against oxidative stress induced by tert-butyl hydroperoxide (t-BHP) in HepG2 cells were investigated through the measurement of aspartate aminotransferase (AST), alanine transaminase (ALT), and superoxide dismutase (SOD) levels. RESULTS: A new phenolic compound identified as 2,3-diferulyl R,R-(+) methyl tartrate (6), in addition to five known metabolites, esculetin (1), esculetin-7-O-d-glucoside (cichoriin) (2), fertaric acid (3), acacetin-7-O-d-glucoside (4), and acacetin-7-O-d-glucuronic acid (5), were isolated. Oxidant-induced damage by 200 µM t-BHP in HepG2 cells was inhibited by compounds 1, 4, and 5 (10 and 20 µM), or quercetin (10 µM; positive control). The protective effects of compounds 1, 4, and 5 were associated with decreasing in AST, ALT, and SOD levels. Compound 4 (20 µM) decreased the AST level from 128.5 ± 13.9 to 7.9 ±1.8 U/mL. Meanwhile, compound 1 (20 µM) decreased ALT activity from 20.3 ± 7.0 to 7.6 ± 2.4 U/mL, while compound 5 decreased SOD levels from 41.6 ± 9.0 to 28.3 ± 3.4 mU/mg. CONCLUSION: The major phenolic compounds isolated from L. spinosa displayed a significant cytoprotective effect against oxidative stress, leading to maintenance of the normal redox status of the cell.

Identification of dialkyl diacetylene diols with potent cancer chemopreventive activity.

An increasing importance of chemoprevention for controlling cancer risks prompted the discovery of new active cancer chemopreventive agents. In this study, we designed and synthesized substituted hexa-2,4-diyne-1,6-diols, more structurally simplified, tunable, and easily preparable than natural gymnasterkoreaynes, and evaluated their cancer chemopreventive activities by measuring concentration of doubling quinone reductase activity (CD), cell viability, and chemopreventive index (CI). Most of the diols exhibited good CD activity and low cytotoxicity. In particular, tetradeca-5,7-diyne-4,9-diol and 2-methyltetradeca-5,7-diyne-4,9-diol showed the best cancer chemopreventive activity, approximately equipotent to that of sulforaphane. And, by synthesizing optically active stereoisomers of selected active compounds, the effect of stereochemistry was also studied. Eventually, we produced a chemopreventive compound for in vivo study.

Daurinol Enhances the Efficacy of Radiotherapy in Lung Cancer via Suppression of Aurora Kinase A/B Expression.

The aurora kinases constitute one family of serine/threonine kinases whose activity is essential for mitotic progression. The aurora kinases are frequently upregulated in human cancers and are associated with sensitivity to chemotherapy in certain ones. In the present study, we investigated whether aurora kinases could be a target to overcome radioresistance or enhance the radiosensitivity of lung cancer. For that purpose, we determined the therapeutic potential of daurinol, an investigational topoisomerase inhibitor, alone and in combination with radiation, by observing its effect on aurora kinases. Daurinol decreased cell viability and proliferation in human colon and lung cancer cells. Gene expression in daurinol-treated human colon cancer cells was evaluated using RNA microarray. The mRNA expression of 18 genes involved in the mitotic spindle check point, including aurora kinase A (AURKA) and aurora kinase B (AURKB), was decreased in daurinol-treated human colon cancer cells as compared with vehicle-treated cells. As expected, radiation increased expression levels of AURKA and AURKB. This increase was effectively attenuated by siRNAs against AURKA and AURKB, which suppressed cell growth and increased apoptosis under radiation. Furthermore, the expression of AURKA and AURKB was suppressed by daurinol in the presence or absence of radiation in colon and lung cancer cells. Daurinol alone or in combination with radiation decreased lung cancer growth in xenograft mouse models. Our data clearly confirm the antitumor and radiosensitizing activity of daurinol in human lung cancer cells through the inhibition of AURKA and AURKB.

Daurinol, a catalytic inhibitor of topoisomerase IIα, suppresses SNU-840 ovarian cancer cell proliferation through cell cycle arrest in S phase.

Daurinol, a lignan from the ethnopharmacological plant Haplophyllum dauricum, was recently reported to be a novel topoisomerase II inhibitor and an alternative to the clinical anticancer agent etoposide based on a colorectal cancer model. In the present study, we elucidated the detailed biochemical mechanism underlying the inhibition of human topoisomerase IIα by daurinol based on a molecular docking study and in vitro biochemical experiments. The computational simulation predicted that daurinol binds to the ATP-binding pocket of topoisomerase IIα. In a biochemical assay, daurinol (10-100 µM) inhibited the catalytic activity of topo-isomerase IIα in an ATP concentration-dependent manner and suppressed the ATP hydrolysis activity of the enzyme. However, daurinol did not inhibit topoisomerase I activity, most likely because topoisomerase I does not contain an ATP-binding domain. We also evaluated the anti-proliferative activity of daurinol in ovarian, small cell lung and testicular cancer cells, common target cancers treated with etoposide. Daurinol potently inhibited SNU-840 human ovarian cancer cell proliferation through cell cycle arrest in S phase, while etoposide induced G2/M phase arrest. Daurinol induced the increased expression of cyclin E, cyclin A and E2F-1, which are important proteins regulating S phase initiation and progression. Daurinol did not induce abnormal cell and nuclear enlargement in SNU-840 cells, in contrast to etoposide. Based on these data, we suggest that daurinol is a potential anticancer drug candidate for the treatment of human ovarian cancer with few side effects.

Crepidiastrum denticulatum extract protects the liver against chronic alcohol-induced damage and fat accumulation in rats.

Alcohol is a severe hepatotoxicant that causes liver abnormalities such as steatosis, cirrhosis, and hepatocarcinoma. Crepidiastrum denticulatum (CD) is a well-known, traditionally consumed vegetable in Korea, which was recently reported to have bioactive compounds with detoxification and antioxidant properties. In this study, we report the hepatoprotective effect of CD extract against chronic alcohol-induced liver damage in vivo. The rats that were given CD extract exhibited decreased alanine aminotransferase, aspartate aminotransferase, and γ-glutamyl transpeptidase activities, which are liver damage markers that are typically elevated by alcohol consumption. The results were confirmed by histopathology with hematoxylin and eosin staining. Chronic alcohol consumption induced the formation of alcoholic fatty liver. However, treatment with CD extract dramatically decreased the hepatic lipid droplets. Treatment with CD extract also restored the antioxidative capacity and lipid peroxidation of the liver that had been changed by alcohol consumption. Furthermore, treatment with CD extract normalized the activities of the antioxidative enzymes superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase, which had been decreased by alcohol consumption. The results indicate that CD extract has protective effects against chronic alcohol hepatotoxicity in rats by increasing the liver's antioxidant capacity, and has potential as a dietary supplement intervention for patients with alcohol-induced liver damage.

Apigenin isolated from Daphne genkwa Siebold et Zucc. inhibits 3T3-L1 preadipocyte differentiation through a modulation of mitotic clonal expansion.

AIMS: Obesity develops when energy intake chronically exceeds total energy expenditure. We sought to assess whether the flavonoid-rich fraction of crude extracts from Daphne genkwa Siebold et Zuccarini (GFF) might inhibit adipogenesis of 3T3-L1 cells. MAIN METHODS: Cell viability of 3T3-L1 preadipocytes was assessed by MTT assays, and lipid accumulation was measured by Oil Red O. Adipogenesis related factors were checked by Western blot analysis. Flow cytometry was used to analyze the mitotic cell cycle during the mitotic clonal expansion phase. KEY FINDINGS: Among five flavonoids isolated from GFF, only apigenin potently inhibited the differentiation of 3T3-L1 cells. Apigenin reduced CCAAT/enhancer binding protein (C/EBP) α and peroxisome proliferator-activated receptor γ levels. Apigenin-treated 3T3-L1 cells failed to undergo clonal expansion during the early phase of adipocyte differentiation. Apigenin arrested cell cycle progression at the G0/G1 phase. This effect was associated with a marked decrease in cyclin D1 and cyclin-dependent kinase 4 expression, with the concomitant and sustained expression of p27(Kip1). In addition, apigenin inhibited the DNA-binding activity of C/EBPß in differentiating 3T3-L1 cells by down-regulating the 35kDa isoform of C/EBPß (liver-enriched activating protein) and up-regulating the expression of two different sets of C/EBP inhibitors: C/EBP homologous protein and the phospho-liver-enriched inhibitory protein isoform of C/EBPß. SIGNIFICANCE: These findings suggest that apigenin can prevent 3T3-L1 preadipocyte differentiation by the inhibition of the mitotic clonal expansion and the adipogenesis related factors and upregulation of the expression of multiple C/EBPß inhibitors.

Secretome profiling reveals the signaling molecules of apoptotic HCT116 cells induced by the dietary polyacetylene gymnasterkoreayne B.

Dietary polyacetylenes from various foods have been receiving attention as promising cancer chemopreventive agents. However, until now, the detailed molecular mechanism and the regulatory proteins underlying these effects have not been elucidated. We investigated the effects of gymnasterkoreayne B (GKB), a model dietary polyacetylene from wild vegetables, on the programmed cell death of HCT116 human colorectal cancer cells. GKB inhibited HCT116 cell proliferation by inducing apoptotic cell death. GKB treatment resulted in ROS accumulation, leading to the activation of both intrinsic and extrinsic apoptotic pathway. We also found that FN1, TGFB1, APP, SERPINE1, HSPD1, SOD1, TXN, and ACTN4 may act as secretory signaling molecules during GKB-induced apoptotic cell death using LC-MS/MS identification followed by spectrum counting, statistical calculation, and gene ontology analysis. The secretory proteins suggested in this study may be promising candidates involved in apoptotic cell death of cancer cells induced by GKB that warrant further functional study.

Antioxidant activity of phenolics in leaves of three red pepper (Capsicum annuum) cultivars.

The antioxidant properties and phenolic profiles were first investigated in this paper on the leaves of three red pepper cultivars, Blackcuban (BCPL), Hongjinju (HPL), and Yeokgang-hongjanggun (YHPL). Of the ethanol extract of the three cultivars, BCPL showed potent antioxidant activities against the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and the 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical. Nine antioxidative compounds from the red pepper leaves were isolated and identified as one polyamine phenolic conjugate, N-caffeoylputrescine (1); three chlorogenic acid derivatives, 5-O-caffeoylquinic acid (2), 5-O-caffeoylquinic acid methyl ester (4), and 5-O-caffeoylquinic acid butyl ester (9); one anthocyanin, delphinidin-3-[4-trans-coumaroyl-l-rhamnosyl(1→6)glucopyranoside]-5-O-glucopyranoside (3); and four flavone glycosides, luteolin-7-O-apiofuranosyl(1→2)glucopyranoside (5), luteolin-7-O-glucopyranoside (6), apigenin 7-O-apiofuranosyl(1→2)glucopyranoside (7), apigenin-7-O-glucopyranoside (8). 1 and 3 had the greatest potential for radical-scavenging activity and HepG2 cells protecting effect against oxidative stress. BCPL exhibited the highest content of 1 and 3. Of the three cultivars BCPL may be considered a good source of antioxidants.

Gymnaster koraiensis and its major components, 3,5-di-O-caffeoylquinic acid and gymnasterkoreayne B, reduce oxidative damage induced by tert-butyl hydroperoxide or acetaminophen in HepG2 cells.

We investigated the protective effects of Gymnaster koraiensis against oxidative stress-induced hepatic cell damage. We used two different cytotoxicity models, i.e., the administration of tert-butyl hydroperoxide (t-BHP) and acetaminophen, in HepG2 cells to evaluate the protective effects of G. koraiensis. The ethyl acetate (EA) fraction of G. koraiensis and its major compound, 3,5-di-O-caffeoylquinic acid (DCQA), exerted protective effects in the t-BHP-induced liver cytotoxicity model. The EA fraction and DCQA ameliorated t-BHP-induced reductions in GSH levels and exhibited free radical scavenging activity. The EA fraction and DCQA also significantly reduced t-BHP-induced DNA damage in HepG2 cells. Furthermore, the hexane fraction of G. koraiensis and its major compound, gymnasterkoreayne B (GKB), exerted strong hepatoprotection in the acetaminophen-induced cytotoxicity model. CYP 3A4 enzyme activity was strongly inhibited by the extract, hexane fraction, and GKB. The hexane fraction and GKB ameliorated acetaminophen-induced reductions in GSH levels and protected against cell death.

Bifunctional chemopreventive effects of Adenocaulon himalaicum through induction of detoxification enzymes and apoptosis.

Phase II detoxification enzymes are known to play essential roles in the detoxification and elimination of activated carcinogens during tumor initiation, while apoptosis is one of the most important chemopreventive targets for inhibiting tumor promotion in cancer. In this study, we investigated the cancer chemopreventive activity of two plant extracts, the ethanolic extract of Adenocaulon himalaicum (AHE) and the butanolic fraction of AHE (AHB). Both, the AHE and AHB induced NQO1 activity and had relatively high chemoprevention indices (CI=12.4). The AHE and AHB were associated with increased NQO1 and HO-1 mRNA levels via Nrf2-ARE pathway activation. In addition, the AHB increased CYP1A1 activity through AhR-XRE pathway activation. We also found that the AHE and AHB induced apoptosis, as evidenced by phosphatidylserine externalization, an increase in the sub-G0/G1 content, chromatin condensation, poly(ADP-ribose) polymerase cleavage, and p53 induction. These data suggest that AHE and AHB act as bifunctional inducers and that their chemopreventive effects result from the biphasic induction of phase II detoxification enzymes and apoptosis. Therefore, these results suggest that A. himalaicum plant extracts have potential for use as chemopreventive agents for the prevention and/or treatment of human cancers.

Protective effect of Paeonia anomala extracts and constituents against tert-butylhydroperoxide-induced oxidative stress in HepG2 cells.

The fruit and root parts of Paeonia anomala L. are used for the treatment of many kinds of disorders in Mongolian traditional medicine. The protective effect of a fruit extract from P. anomala against tert-butylhydroperoxide-induced cell damage was evaluated in human hepatoma HepG2 cells and compared to that of a root extract from P. anomala on the basis of cell viability, generation of intracellular reactive oxygen species, cellular total glutathione concentration, and anti-genotoxicity. The fruit extract of P. anomala showed excellent protection against the oxidative stress when compared to the root extract, through free radical scavenging, enhancing cellular glutathione concentration, and inhibiting DNA damage. Chemical constituents in the fruit extract of P. anomala were investigated and two novel compounds, 2-hydroxy-6-methoxy-4-O-(6'-O-α-L-arabinofuranosyl-ß-D-glucopyranosyl)acetophenone (1) and 3,3'-di-O-methyl-4-O-(3''-O-galloyl-ß-D-glucopyranosyl)ellagic acid (2), along with 18 other known compounds were identified. Compound 2 showed better cytoprotection against tert-butylhydroperoxide than compound 1. Among other compounds isolated from the fruit extract, ellagic acid, methyl gallate, ethyl gallate, fischeroside B, and quercetin derivatives showed potent protective effects against tert-butylhydroperoxide-induced oxidative stress via inhibiting reactive oxygen species generation and increasing total glutathione levels in HepG2 cells.

Nuclear factor-E2 (Nrf2) is regulated through the differential activation of ERK1/2 and PKC α/ßII by Gymnasterkoreayne B.

Phytochemicals are well known to have cancer chemopreventive effects by induction of phase II detoxification enzymes including quinone reductase (NQO-1) and glutathione-S-transferases. These detoxification enzymes are commonly regulated by nuclear factor-E2 (Nrf2), which is a representative antioxidant and cytoprotective factor involved in cancer chemoprevention. As one of the known quinone reductase (QR) inducers and Nrf2 activators, Gymnasterkoreayne B (GKB) isolated from Gymnaster (Aster) koraiensis was used to elucidate the upstream signalling pathway for Nrf2 regulation. In this study, we confirmed that GKB significantly increases expression levels of Nrf2 in HCT116 human colon cancer cells. We found the probable mechanism of upstream signalling pathways to activate Nrf2 by GKB. To reveal the pathway that affects Nrf2 translocation by GKB, we examined changes in various kinases in HCT116 cells treated with GKB. We observed that ERK and PKC pathways are particularly involved in the activation of Nrf2 by GKB, followed by translocation of Nrf2 and induction of NQO-1. These results suggest that GKB induces Nrf2 translocation and expression by differential regulation of ERK and PKC pathways in HCT116 cells.

Dibenzocyclooctadiene lignans, gomisins J and N inhibit the Wnt/ß-catenin signaling pathway in HCT116 cells.

Here, we report that gomisin J and gomisin N, dibenzocyclooctadiene type lignans isolated from Schisandra chinensis, inhibit Wnt/ß-catenin signaling in HCT116 cells. Gomisins J and N appear to inhibit Wnt/ß-catenin signaling by disrupting the interaction between ß-catenin and its specific target DNA sequences (TCF binding elements, TBE) rather than by altering the expression of the ß-catenin protein. Gomisins J and N inhibit HCT116 cell proliferation by arresting the cell cycle at the G0/G1 phase. The G0/G1 phase arrest induced by gomisins J and N appears to be caused by a decrease in the expression of Cyclin D1, a representative target gene of the Wnt/ß-catenin signaling pathway, as well as Cdk2, Cdk4, and E2F-1. Therefore, gomisins J and N, the novel Wnt/ß-catenin inhibitors discovered in this study, may serve as potential agents for the prevention and treatment of human colorectal cancers.