4-O-methylhonokiol inhibits colon tumor growth via p21-mediated suppression of NF-κB activity.

Biphenolic components in the Magnolia family have shown several pharmacological activities such as antitumor effects. This study investigated the effects of 4-O-methylhonokiol (MH), a constituent of Magnolia officinalis, on human colon cancer cell growth and its action mechanism. 4-O-methylhonokiol (0-30 µM) decreased constitutive activated nuclear factor (NF)-κB DNA binding activity and inhibited growth of human colon (SW620 and HCT116) cancer cells. It also caused G0-G1 phase cell cycle arrest followed by an induction of apoptotic cell death. However, knockdown with small interfering RNA (siRNA) of p21 or transfection with cyclin D1/Cdk4 binding site-mutated p21 abrogated MH-induced cell growth inhibition, inhibition of NF-κB activity as well as expression of cyclin D1 and Cdk4. Conversely, inhibition of NF-κB with specific inhibitor or siRNA augmented MH-induced apoptotic cell death. 4-O-methylhonokiol inhibited tumor growth, NF-κB activity and expression of antiapoptotic proteins; however, it increased the expression of apoptotic proteins as well as p21 in xenograft nude mice bearing SW620 cancer cells. The present study reveals that MH causes p21-mediated human colon cancer cell growth inhibition through suppression of NF-κB and indicates that this compound by itself or in combination with other anticancer agents could be useful for the treatment of cancer.

Troglitazone, a PPAR agonist, inhibits human prostate cancer cell growth through inactivation of NFκB via suppression of GSK-3ß expression.

PPARγ ligands have been reported to reduce proliferation of human prostate cancer cells. However, the molecular mechanism of PPARγ agonist-induced cell growth inhibition of prostate cancer cells is not clear. GSK-3ß expression and NFκB activity have important roles in prostate cancer development. To investigate the mechanisms of the PPARγ agonist-induced prostate cancer cell growth inhibition, we examined the effect of troglitazone on the expression of PPARγ, GSK-3ß and activity of NFκB as well as on the prostate cancer cell growth. Troglitazone induced the expression of PPARγ in the nuclear of PC-3 cells, but not in LNCaP cells. Troglitazone (0-16 uM) inhibited cancer cell growth in a similar extend between both cells accompanied by the induction of cell cycle arrest in G(0)/G(1) phase and an increased in the similar extent of apoptotic cell death in concentration dependent manner. Troglitazone inhibited the constitutive expression of GSK-3ß and activation of NFκB. Co-treatment of troglitazone with a GSK-3ß inhibitor (AR-a014418) or GSK-3ß siRNA significantly augmented the inhibitory effect of troglitazone on the NFκB activity and on prostate cancer cell growth inhibition and apoptotic cell death. However, overexpression of GSK-3ß hindered troglitazone-induced cell growth inhibition and NFκB inactivation. These results suggest that PPARγ agonist, troglitazone, inhibits prostate cancer cell growth through inactivation of NFκB via suppression of GSK-3ß expression.

(-)-Epigallocatechin-3-O-gallate (EGCG) reverses caffeine-induced anxiogenic-like effects.

This study was designed to determine whether (-)-epigallocatethin-3-O-gallate (EGCG) could reverse caffeine-induced anxiogenic-like effects in animals. In mice, EGCG antagonized the caffeine-induced reduction in both the open arm entry number and time-spent in open arm on elevated plus-maze. In addition, EGCG also antagonized the caffeine-induced reduction in both the central zone distance and central zone time-spent on an open field apparatus, respectively. Electroencephalogram (EEG) was recorded from the rat anterior cerebral cortex. Caffeine increased the power density-ratios of fast (FW: 8.00-20.00 Hz) and slow (SW: 0.75-8.00 Hz) frequency spectrum bands in these EEG recordings. However, EGCG reduced the caffeine-induced increase of FW/SW ratios. Thus, EGCG reverses caffeine-induced anxiogenic-like effects. We also provide additional evidence that the EEG FW/SW (or SW/FW) ratios can be a useful tool for the prediction of anxiogenic and/or anxiolytic effects in an animal model.

Suppression of NF-kappaB and GSK-3beta is involved in colon cancer cell growth inhibition by the PPAR agonist troglitazone.

Peroxisome proliferator-activated receptor (PPAR)-gamma agonists such as troglitazone, pioglitazone and thiazolidine have been shown to induce apoptosis in human colon cancer cells. The molecular mechanism of PPARgamma agonist-induced apoptosis of colon cancer cells, however, is not clear. Glycogen synthase kinase-3beta (GSK-3beta) is an indispensable element for the activation of nuclear factor-kappa B (NF-kappaB) which plays a critical role in the mediation of survival signals in cancer cells. To investigate the mechanisms of PPARgamma agonist-induced apoptosis of colon cancer cells, we examined the effect of troglitazone (0-16muM) on the activation of GSK-3beta and NF-kappaB. Our study showed that the inhibitory effect of troglitazone on colon cancer cell growth was associated with inhibition of NF-kappaB activity and GSK-3beta expression in a dose-dependent manner. Cells were arrested in G(0)/G(1) phase followed by the induction of apoptosis after treatment of troglitazone with concomitant decrease in the expression of the G(0)/G(1) phase regulatory proteins; Cdk2, Cdk4, cyclin B1, D1, and E as well as in the anti-apoptosis protein Bcl-2 along with an increase in the expression of the pro-apoptosis-associated proteins; Caspase-3, Caspase-9 and Bax. Transient transfection of GSK-3beta recovered troglitazone-induced cell growth inhibition and NF-kappaB inactivation. In contrast, co-treatment of troglitazone with a GSK-3beta inhibitor (AR-a014418) or siRNA against GSK-3beta, significantly augmented the inhibitory effect of troglitazone on the NF-kappaB activity, the cancer cell growth and on the expression of G(0)/G(1) phase regulatory proteins and pro-apoptosis regulatory proteins. These results suggest that the PPARgamma agonist, troglitazone, inhibits colon cancer cell growth via inactivation of NF-kappaB by suppressing GSK-3beta activity.

Anti-inflammatory and arthritic effects of thiacremonone, a novel sulfur compound isolated from garlic via inhibition of NF-kappaB.

INTRODUCTION: Sulfur compounds isolated from garlic exert anti-inflammatory properties. We recently isolated thiacremonone, a novel sulfur compound from garlic. Here, we investigated the anti-inflammatory and arthritis properties of thiacremonone through inhibition of NF-kappaB since NF-kappaB is known to be a target molecule of sulfur compounds and an implicated transcription factor regulating inflammatory response genes. METHODS: The anti-inflammatory and arthritis effects of thiacremone in in vivo were investigated in 12-O-tetradecanoylphorbol-13-acetate-induced ear edema, carrageenan and mycobacterium butyricum-induced inflammatory and arthritis models. Lipopolysaccharide-induced nitric oxide (NO) production was determined by Griess method. The DNA binding activity of NF-kappaB was investigated by electrophoretic mobility shift assay. NF-kappaB and inducible nitric oxide synthetase (iNOS) transcriptional activity was determined by luciferase assay. Expression of iNOS and cyclooxygenase-2 (COX-2) was determined by western blot. RESULTS: The results showed that topical application of thiacremonone (1 or 2 microg/ear) suppressed the 12-O-tetradecanoylphorbol-13-acetate-induced (1 microg/ear) ear edema. Thiacremonone (1-10 mg/kg) administered directly into the plantar surface of hind paw also suppressed the carrageenan (1.5 mg/paw) and mycobacterium butyricum (2 mg/paw)-induced inflammatory and arthritic responses as well as expression of iNOS and COX-2, in addition to NF-kappaB DNA-binding activity. In further in vitro study, thiacremonone (2.5-10 microg/ml) inhibited lipopolysaccharide (LPS, 1 microg/ml)-induced nitric oxide (NO) production, and NF-kappaB transcriptional and DNA binding activity in a dose dependent manner. The inhibition of NO by thiacremonone was consistent with the inhibitory effect on LPS-induced inducible nitric oxide synthase (iNOS) and COX-2 expression, as well as iNOS transcriptional activity. Moreover, thiacremonone inhibited LPS-induced p50 and p65 nuclear translocation, resulting in an inhibition of the DNA binding activity of the NF-kappaB. These inhibitory effects on NF-kappaB activity and NO generation were suppressed by reducing agents dithiothreitol (DTT) and glutathione, and were abrogated in p50 (C62S)-mutant cells, suggesting that the sulfhydryl group of NF-kappaB molecules may be a target of thiacremonone. CONCLUSIONS: The present results suggested that thiacremonone exerted its anti-inflammatory and anti-arthritic properties through the inhibition of NF-kappaB activation via interaction with the sulfhydryl group of NF-kappaB molecules, and thus could be a useful agent for the treatment of inflammatory and arthritic diseases.

Inflexinol inhibits colon cancer cell growth through inhibition of nuclear factor-kappaB activity via direct interaction with p50.

Kaurane diterpene compounds have been known to be cytotoxic against several cancer cells through inhibition of nuclear factor-kappaB (NF-kappaB) activity. Here, we showed that inflexinol, a novel kaurane diterpene compound, inhibited the activity of NF-kappaB and its target gene expression as well as cancer cell growth through induction of apoptotic cell death in vitro and in vivo. These inhibitory effects on NF-kappaB activity and on cancer cell growth were suppressed by the reducing agents DTT and glutathione and were abrogated in the cells transfected with mutant p50 (C62S). Sol-gel biochip and surface plasmon resonance analysis showed that inflexinol binds to the p50 subunit of NF-kappaB. These results suggest that inflexinol inhibits colon cancer cell growth via induction of apoptotic cell death through inactivation of NF-kappaB by a direct modification of cysteine residue in the p50 subunit of NF-kappaB.

Anti-inflammatory effect of 4-O-methylhonokiol, compound isolated from Magnolia officinalis through inhibition of NF-kappaB [corrected].

The bioactive constituents isolated from the bark of Magnolia officinalis such as magnolol, honokiol and obovatol have anti-inflammatory properties through the inactivation of NF-kappaB which is an important factor in the regulation of inflammatory reaction. We recently isolated neolignan compound, 4-O-methylhonokiol, from M. officinalis. In the present study, we investigated whether or not 4-O-methylhonokiol inhibits inflammatory reaction through the inhibition of NF-B activity [corrected]. The results showed that 4-O-methylhonokiol (2.5-10 microM) inhibited LPS (1 microg/ml)-induced NO generation in macrophage Raw 264.7 cells in a concentration-dependent manner with IC(50) value 9.8 microM. The inhibition of NO generation by 4-O-methylhonokiol was consistent with the inhibitory effect on the expression as well as transcriptional activity of inducible nitric oxide synthase (iNOS). In addition, 4-O-methylhonokiol inhibited the LPS-induced transcriptional and DNA binding activities of NF-kappaB as well as p50 and p65 translocation into the nucleus. Topical application of 4-O-methylhonokiol (0.1-1 mg/ear) inhibited 12-O-tetradecanoylphorbol-13-acetate-induced inflammatory ear edema formation, NF-kappaB activity, and iNOS and COX-2 expression. The present results provided evidence that 4-O-methylhonokiol has anti-inflammatory properties through inhibition of the NF-kappaB pathway, and suggested that 4-O-methylhonokiol can be used as an anti-inflammatory agent.

Berberine inhibits p53-dependent cell growth through induction of apoptosis of prostate cancer cells.

Berberine has anti-tumor properties in some cancer cells including prostate cancer, but the exact mechanisms and in vivo effects are unclear. We investigated anti-cancer activity of berberine in vitro and in vivo, and possible mechanisms in prostate cancer cells. Berberine treatment inhibited cell cancer growth in a concentration (0-50 microM) and time- (0-48 h) dependent manner without any growth inhibition in normal human prostate epithelial PWR-1E cells. However, the p53 expressing LNCaP cells were more susceptible against berberine than the p53 lacking PC-3 cells. The cell arrest in G0/G1 phase, apoptotic cell death and the expression of apoptotic cell death proteins Bax and caspase-3 was much higher in berberine-treated LNCaP cells than those in PC-3 cells. Exploration of p53 siRNA or pifithrin-alpha, a p53 inhibitor to the LNCaP cells, suppressed berberine-induced cell death and expression of apoptosis-related proteins. In xenograft in vivo studies, berberine reduced tumor weights and volumes accompanied with apoptotic cell death and increased expression of apoptotic cell death proteins, however, the extent of inhibitory effect was more significant in LNCaP cell-bearing mice. Therefore, these results indicated that berberine inhibited p53-dependent prostate cancer cell death.

Berberine inhibits human neuroblastoma cell growth through induction of p53-dependent apoptosis.

Berberine, an alkaloid, has anti-tumor properties in some cancer cells, but action mechanisms are not clear yet. We here investigated the anticancer activity of berberine and possible mechanisms in human neuroblastoma SK-N-SH and SK-N-MC cells. The p53-expressing cells, SK-N-SH (IC50=37 microM) were more susceptible to berberine than the p53-deficient cells, SK-N-MC (IC50 > or =100 microM) without cytotoxic effect on the cortical neuronal cells. Berberine caused cell cycle arrest in G0/G1 phase and apoptotic cell death, and these effects were much greater in SK-N-SH cells than those in SK-N-MC cells. Berberine much greatly decreased G0/G1 phase-associated cyclin and cyclin-dependent kinase (cyclin D1, cyclin E, Cdk2, and Cdk4) expression, and increased apoptotic gene expression and activation of caspase-3 in SK-N-SH cells. Exploration of p53 siRNA or pifithrin-alpha (PFT-alpha), a p53 inhibitor, in the SK-N-SH cells resulted in increase of IC50 values for cell viability, and decreased apoptotic cell death, expression of p53 and activation of caspase-3. Therefore, these results showed that berberine causes p53-dependent apoptotic death of neuroblastoma cells, and suggested that berberine may be useful as an anticancer agent for neuroblastoma.