Targeting of magnolin on ERKs inhibits Ras/ERKs/RSK2-signaling-mediated neoplastic cell transformation

Magnolin Inhibits Paclitaxel-Induced Cold Allodynia and ERK1/2 Activation in Mice

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of anti-cancer drugs. The main symptoms often include sensory disturbances and neuropathic pain, and currently there is no effective treatment for this condition. This study aimed to investigate the suppressive effects of magnolin, an extracellular signal-regulated kinase (ERK) inhibitor substance derived from a 95% EtOH extract of the seeds of Magnolia denudata, on the symptoms of CIPN. A taxol-based anti-cancer drug paclitaxel (PTX) was repeatedly injected (2 mg/kg/day, total 8 mg/kg) into mice to induce CIPN. A neuropathic pain symptom was assessed using a cold allodynia test that scores behaviors of licking and shaking paw after plantar administration of acetone drop. Magnolin was administered intraperitoneally (0.1, 1, or 10 mg/kg) and behavioral changes to acetone drop were measured. The effect of magnolin administration on ERK expression in the dorsal root ganglion (DRG) was investigated using western blot analysis. The results showed that the repeated injections of PTX induced cold allodynia in mice. Magnolin administration exerted an analgesic effect on the PTX-induced cold allodynia and inhibited the ERK phosphorylation in the DRG. These results suggest that magnolin could be developed as an alternative treatment to suppress paclitaxel-induced neuropathic pain symptoms.

Anticancer Potentials of the Lignan Magnolin: A Systematic Review

Magnolin is a naturally occurring, multi-bioactive lignan molecule with inherent anticancer effects. This study aims to summarize the botanical origins and anticancer properties of magnolin. For this, a recent (as of March 2023) literature review was conducted using various academic search engines, including PubMed, Springer Link, Wiley Online, Web of Science, Science Direct, and Google Scholar. All the currently available information about this phytochemical and its role in various cancer types has been gathered and investigated. Magnolin is a compound found in many different plants. It has been demonstrated to have anticancer activity in numerous experimental models by inhibiting the cell cycle (G1 and G2/M phase); inducing apoptosis; and causing antiinvasion, antimetastasis, and antiproliferative effects via the modulation of several pathways. In conclusion, magnolin showed robust anticancer activity against many cancer cell lines by altering several cancer signaling pathways in various non- and pre-clinical experimental models, making it a promising plant-derived chemotherapeutic option for further clinical research.

New Sesquiterpene Glycosides from the Flowers of Aster koraiensis and Their Inhibition Activities on EGF- and TPA-Induced Cell Transformation

In total, four new eudesmane-type sesquiterpene glycosides, askoseosides A-D (1-4), and 18 known compounds (5-22) were isolated from the flowers of Aster koraiensis via chromatographic techniques. Chemical structures of the isolated compounds were identified by spectroscopic/spectrometric methods, including NMR and HRESIMS, and the absolute configuration of the new compounds (1 and 2) was performed by electronic circular dichroism (ECD) studies. Further, the anticancer activities of the isolated compounds (1-22) were evaluated using the epidermal growth factor (EGF)-induced as well as the 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced cell transformation assay. Among the 22 compounds, compounds 4, 9, 11, 13-15, 17, 18, and 22 significantly inhibited both EGF- and TPA-induced colony growth. In particular, askoseoside D (4, EGF: 57.8%; TPA: 67.1%), apigenin (9, EGF: 88.6%; TPA: 80.2%), apigenin-7-O-β-d-glucuronopyranoside (14, EGF: 79.2%; TPA: 70.7%), and 1-(3',4'-dihydroxycinnamoyl) cyclopentane-2,3-diol (22, EGF: 60.0%; TPA: 72.1%) showed higher potent activities.

Novel wiring of the AKT-RSK2 signaling pathway plays an essential role in cancer cell proliferation via a G1/S cell cycle transition

p90 Ribosomal S6 kinase 2 (RSK2), a member of mitogen-activated protein kinase regulating cell proliferation and transformation induced by tumor promoters, such as epidermal growth factor, plays a vital role as a signaling hub to modulate cell proliferation, transformation, cell cycle transition, and chromatin remodeling by tumor promoter stimulation such as epidermal growth factor. On the other hand, the RSK2-mediated signaling networks that regulate cancer cell proliferation are unclear. In this study, SKOV3, an ovarian cancer cell that exhibits chemoresistant properties, and TOV-112D cells showed different sensitivities to colony growth in soft agar. Based on the protein profile shown in a previous report, RSK2 knockdown preferentially and significantly suppressed cell proliferation and colony growth. Moreover, RSK2 interacted with AKTs (AKT 1-3) via the N-terminal kinase domain (NTKD) of RSK2, resulting in the phosphorylation of RSK2. The AKT-mediated phosphorylation consensus sequence, RxRxxS/T, on RSK2 NTKD (Thr115) was well conserved in different species. In particular, an in vitro kinase assay showed that NTKD deleted and Thr115Ala mutants of RSK2 abolished AKT1-mediated phosphorylation. In the physiological assay of RSK2 phosphorylation at Thr115 on cell proliferation, AKT1-mediated RSK2 phosphorylation at Thr115 played an essential role in cell proliferation. The re-introduction of RSK2-T115A to RSK2^-/- MEF attenuated the EGF-induced G₁/S cell cycle transition compared to RSK2-wt introducing RSK2^-/- MEFs. This attenuation was observed by EGF stimulations and insulin-like growth factor-1. Overall, these results show that novel wiring of the AKT/RSKs signaling axis plays an important role in cancer cell proliferation by modulating the G₁/S cell cycle transition.

Identification of key genes involved in tamoxifen-resistant breast cancer using bioinformatics analysis

Background

The purpose of the present study was to investigate the molecular mechanisms of tamoxifen resistance in breast cancer and to identify potential targets for antitamoxifen resistance.

Methods

Differentially expressed genes (DEGs) in tamoxifen-resistant and tamoxifen-sensitive breast cancer cells were assessed using the GSE67916 dataset acquired from the Gene Expression Omnibus database. Gene ontology (GO) and pathway enrichment analyses were applied to investigate the functions and pathways of the DEGs. Subsequently, the protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING), and subnetworks were further analyzed by Molecular Complex Detection (MCODE). The PPI network and subnetworks were visualized using Cytoscape software.

Results

In total, 438 DEGs were identified, of which 300 were upregulated and 138 were downregulated. The DEGs were significantly enriched in the protein binding, cellular response to estradiol stimulus, and immune response GO terms while the most significant pathways included the mitogen-activated protein kinase (MAPK) signaling pathway in cancer. The PPI network of DEGs was constructed with 288 nodes and 629 edges, and 2 subnetworks were screened out from the entire network.

Conclusions

A number of significant hub DEGs were identified based on their degree of connectivity in the PPI network, , included MAPK1 (node degree 36), ESR1 (node degree 27), SMARCA4 (node degree 27), RANBP2 (node degree 25), and PRKCA (node degree 21). These critical hub genes were found to be related to tamoxifen resistance in breast cancer. The results of this study further the understanding of tamoxifen resistance at the molecular level and identify potential therapeutic targets for tamoxifen-resistant breast cancer.

Kaempferol sensitizes cell proliferation inhibition in oxaliplatin-resistant colon cancer cells

Resolution to chemoresistance is a major challenge in patients with advanced-stage malignancies. Thus, identification of action points and elucidation of molecular mechanisms for chemoresist human cancer are necessary to overcome this challenge. In this study, we provide important evidence that kaempferol targeting RSKs might be a strategy to reduce the oxaliplatin-resistant colon cancer cells. We found that MAPK and PI3K-AKT signaling were increased in oxaliplatin (Ox)-resistant HCT116 (HCT116-Ox^R) cells compared to Ox-sensitive HCT116 (HCT116-Ox^S) cells. Comparison of cell sensitivities using SP600125 (JNK inhibitor), SB206580 (p38 kinase inhibitor), or MK-2206 (AKT inhibitor) revealed that cell proliferation inhibition was strongly observed in HT29 cells compared to that in HCT116 cells in both Ox^S and Ox^R cells. Interestingly, SP600125, SB206580, and MK-2206 treatment showed higher cell proliferation inhibition in Ox^S cells than that in Ox^R cells in both HCT116 and HT29 cells, except following treatments with 10 µM of SP600125, and 30 µM of SB206580. In comparison to magnolin and aschantin, kaempferol showed the strongest inhibitory effect on cell proliferation in both HCT116 and HT29 cells. Importantly, HCT116- and HT29-Ox^R cells showed higher sensitivities to cell proliferation inhibition than those of HCT116- and HT29-Ox^S cells, resulting in the accumulation of cells at the G₂/M-phases of the cell cycle. Finally, we showed that AP-1 transactivation activity was markedly decreased by kaempferol in HCT116- and HT29-Ox^R cells compared to the activity levels in HCT116- and HT29-Ox^S cells. Taken together, the results demonstrate that kaempferol-mediated AP-1 inhibition might be an important signaling mechanism to resolve the chemoresistance of Ox-resistant colon cancer cells.

Friend or Foe: Paradoxical Roles of Autophagy in Gliomagenesis

Glioblastoma multiforme (GBM) is the most common and aggressive type of primary brain tumor in adults, with a poor median survival of approximately 15 months after diagnosis. Despite several decades of intensive research on its cancer biology, treatment for GBM remains a challenge. Autophagy, a fundamental homeostatic mechanism, is responsible for degrading and recycling damaged or defective cellular components. It plays a paradoxical role in GBM by either promoting or suppressing tumor growth depending on the cellular context. A thorough understanding of autophagy's pleiotropic roles is needed to develop potential therapeutic strategies for GBM. In this paper, we discussed molecular mechanisms and biphasic functions of autophagy in gliomagenesis. We also provided a summary of treatments for GBM, emphasizing the importance of autophagy as a promising molecular target for treating GBM.

Fargesin Inhibits EGF-Induced Cell Transformation and Colon Cancer Cell Growth by Suppression of CDK2/Cyclin E Signaling Pathway

Although the lignan compound fargesin is a major ingredient in Shin-Yi, the roles of fargesin in carcinogenesis and cancer cell growth have not been elucidated. In this study, we observed that fargesin inhibited cell proliferation and transformation by suppression of epidermal growth factor (EGF)-stimulated G₁/S-phase cell cycle transition in premalignant JB6 Cl41 and HaCaT cells. Unexpectedly, we found that signaling pathway analyses showed different regulation patterns in which fargesin inhibited phosphatidylinositol 3-kinase/AKT signaling without an alteration of or increase in mitogen activated protein kinase (MAPK) in JB6 Cl41 and HaCaT cells, while both signaling pathways were abrogated by fargesin treatment in colon cancer cells. We further found that fargesin-induced colony growth inhibition of colon cancer cells was mediated by suppression of the cyclin dependent kinase 2 (CDK2)/cyclin E signaling axis by upregulation of p21^WAF1/Cip1, resulting in G₁-phase cell cycle accumulation in a dose-dependent manner. Simultaneously, the suppression of CDK2/cyclin E and induction of p21^WAF1/Cip1 were correlated with Rb phosphorylation and c-Myc suppression. Taken together, we conclude that fargesin-mediated c-Myc suppression inhibits EGF-induced cell transformation and colon cancer cell colony growth by the suppression of retinoblastoma (Rb)-E2F and CDK/cyclin signaling pathways, which are mainly regulated by MAPK and PKB signaling pathways.

Magnolin Inhibits Proliferation and Invasion of Breast Cancer MDA-MB-231 Cells by Targeting the ERK1/2 Signaling Pathway

The aim of this study was to evaluate the effects of Magnolin (MGL) on inhibition of human breast cancer cells, and explore the underlying molecular mechanisms. The viability of the treated cells was assessed with the Cell Counting Kit-8 (CCK-8) assay, and the proliferation was analyzed in terms of EdU uptake, colony formation, and flow cytometry. The in vitro invasion and migration were determined by the transwell and wound healing assays respectively. The mRNA and protein levels of relevant factors was evaluated by quantitative real-time PCR and Western blotting respectively. MGL significantly decreased the viability and promoted apoptosis of MDA-MB-231 cells, along with reducing EdU incorporation rate as well as the colony forming capacity compared to the untreated control cells. In addition, the in vitro invasion and migration were also significantly inhibited by MGL. Furthermore, MGL suppressed the phosphorylation of MEK1/2, extracellular signal-regulated kinase (ERK)1/2 and significantly downregulated the expression of cyclin-dependent kinase 1 (CDK1), the anti-apoptotic B-cell lymphoma 2 (BCL2) and metastasis-associated matrix metalloproteases (MMPs) 2 & 9, and upregulated the cleaved caspases 3 and 9. After ERK was completely inhibited with the small interfering RNA (siRNA), MGL had no effect on these factors, indicating that ERK is essential for MGL action in breast cancer. In conclusion, MGL inhibits proliferation and invasion of and induces apoptosis in breast cancer cells through the ERK pathway.

Epimagnolin targeting on an active pocket of mammalian target of rapamycin suppressed cell transformation and colony growth of lung cancer cells

Mammalian target of rapamycin (mTOR) has a pivotal role in carcinogenesis and cancer cell proliferation in diverse human cancers. In this study, we observed that epimagnolin, a natural compound abundantly found in Shin-Yi, suppressed cell proliferation by inhibition of epidermal growth factor (EGF)-induced G1/S cell-cycle phase transition in JB6 Cl41 cells. Interestingly, epimagnolin suppressed EGF-induced Akt phosphorylation strongly at Ser473 and weakly at Thr308 without alteration of phosphorylation of MAPK/ERK kinases (MEKs), extracellular signal-regulated kinase (ERKs), and RSK1, resulting in abrogation of the phosphorylation of GSK3β at Ser9 and p70S6K at Thr389. Moreover, we found that epimagnolin suppressed c-Jun phosphorylation at Ser63/73, resulting in the inhibition of activator protein 1 (AP-1) transactivation activity. Computational docking indicated that epimagnolin targeted an active pocket of the mTOR kinase domain by forming three hydrogen bonds and three hydrophobic interactions. The prediction was confirmed by using in vitro kinase and adenosine triphosphate-bead competition assays. The inhibition of mTOR kinase activity resulted in the suppression of anchorage-independent cell transformation. Importantly, epimagnolin efficiently suppressed cell proliferation and anchorage-independent colony growth of H1650 rather than H460 lung cancer cells with dependency of total and phosphorylated protein levels of mTOR and Akt. Inhibitory signaling of epimagnolin on cell proliferation of lung cancer cells was observed mainly in mTOR-Akt-p70S6K and mTOR-Akt-GSK3β-AP-1, which was similar to that shown in JB6 Cl41 cells. Taken together, our results indicate that epimagnolin potentiates as chemopreventive or therapeutic agents by direct active pocket targeting of mTOR kinase, resulting in sensitizing cancer cells harboring enhanced phosphorylation of the mTORC2-Akt-p70S6k signaling pathway.

Magnolin targeting of ERK1/2 inhibits cell proliferation and colony growth by induction of cellular senescence in ovarian cancer cells

Ras/Raf/MEKs/ERKs and PI3 K/Akt/mTOR signaling pathways have key roles in cancer development and growth processes, as well as in cancer malignance and chemoresistance. In this study, we screened the therapeutic potential of magnolin using 15 human cancer cell lines and combined magnolin sensitivity with the CCLE mutaome analysis for relevant mutation information. The results showed that magnolin efficacy on cell proliferation inhibition were lower in TOV-112D ovarian cancer cells than that in SKOV3 cells by G1 and G2/M cell cycle phase accumulation. Notably, magnolin suppressed colony growth of TOV-112D cells in soft agar, whereas colony growth of SKOV3 cells in soft agar was not affected by magnolin treatment. Interestingly, phospho-protein profiles in the MAPK and PI3 K signaling pathways indicated that SKOV3 cells showed marked increase of Akt phosphorylation at Thr308 and Ser473 and very weak ERK1/2 phosphorylation levels by EGF stimulation. The phospho-protein profiles in TOV-112D cells were the opposite of those of SKOV3 cells. Importantly, magnolin treatment suppressed phosphorylation of RSKs in TOV-112D, but not in SKOV3 cells. Moreover, magnolin increased SA-β-galactosidase-positive cells in a dose-dependent manner in TOV-112D cells, but not in SKOV3 cells. Notably, oral administration of Shin-Yi fraction 1, which contained magnolin approximately 53%, suppressed TOV-112D cell growth in athymic nude mice by induction of p16Ink4a and p27Kip1 . Taken together, targeting of ERK1 and ERK2 is suitable for the treatment of ovarian cancer cells that do not harbor the constitutive active P13 K mutation and the loss-of-function mutations of the p16 and/or p53 tumor suppressor proteins.

Lignans Isolated From Flower Buds of Magnolia fargesii Attenuate Airway Inflammation Induced by Cigarette Smoke in vitro and in vivo

The flower buds of Magnolia fargesii, known traditionally as Xinyi, exert anti-inflammatory effects against inflammatory lung diseases such as COPD. Lignans isolated from Xinyi are an important group of plant-derived anti-inflammatory compounds. However, the mechanisms of action underlying their protective effects against COPD are not yet fully understood. Here, we showed that seven lignans (lignans 1–7) obtained from a CHCl₃ fraction of Xinyi effectively suppress the inflammatory response in CSC-stimulated airway epithelial cells (in vitro) and in a mouse model of COPD established by exposure to CS and LPS. The CHCl₃ fraction was found to inhibit CSC-induced IL-6 expression in human airway epithelial cells and to suppress the infiltration of inflammatory cells (neutrophils and macrophages) and secretion of inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the mouse model. Similarly, each of the seven lignans isolated from the CHCl₃ fraction also suppressed the infiltration of inflammatory cells (neutrophils and macrophages) and secretion of inflammatory mediators such as reactive oxygen species (ROS), TNF-α, and IL-6 in vivo. Notably, all lignan compounds significantly suppressed both extracellular signal-related kinase (ERK) and Akt phosphorylation levels in CSC-stimulated human lung mucoepidermoid carcinoma (NCI-H292) cells. Of these, lignan 1 (dimethylpinoresinol) inhibited the expression of CSC-induced inflammatory cytokines (IL-1β, -6, and -8) in vitro in a dose-dependent manner by suppressing the activation of epidermal growth factor receptor (EGFR) and its downstream effectors, including ERK and Akt, in NCI-H292 cells. Our results show that the lignans isolated from Xinyi may prevent airway inflammatory diseases through the suppression of EGFR and its downstream effectors.

Magnolin promotes autophagy and cell cycle arrest via blocking LIF/Stat3/Mcl-1 axis in human colorectal cancers

Magnolin is a multi-bioactive natural compound that possesses underlying anti-cancer properties. However, the mechanisms underlying remain to be elucidated. Here, we report the role of magnolin in suppressing human colorectal cancer (CRC) cells via activating autophagy and cell cycle arrest in vitro and in vivo. Pre-treatment of cells with specific autophagy inhibitor (3-methyladenine) or knockdown of endogenous LC-3B by siRNA significantly abrogates magnolin-induced cell cycle arrest. Molecular validation mechanistically shows that magnolin-induced autophagy and cell cycle arrest in CRC cells is correlated with decreased transcriptional levels of leukemia inhibitory factor (LIF), and we further find that inhibition of LIF decreases phosphorylation level of Stat3 and represses transcriptional expression of Mcl-1. Furthermore, magnolin-induced autophagy and cell cycle arrest suppress the growth of xenograft colorectal tumors without apparent toxicity. Finally, we evaluate the clinical correlation of LIF/Stat3/Mcl-1 in CRC patient tissues. As expected, LIF, p-Stat3, and Mcl-1 levels are high in CRC tissue but are scarcely found in normal colon tissue. High positive expressions of LIF or Mcl-1 are associated with poor prognosis. Doubly positive cases have shown the worst outcome. Taken together, our results have clarified a novel molecular mechanism whereby magnolin induces autophagy and cell cycle arrest through LIF/Stat3/Mcl-1 pathway in CRCs. Our results also have revealed that magnolin has a promising therapeutic potential in CRCs.

Kaempferol targeting on the fibroblast growth factor receptor 3-ribosomal S6 kinase 2 signaling axis prevents the development of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic inflammatory disease that mainly affects the synovial joints. Although involvement of the fibroblast growth factor (FGF) signaling pathway has been suggested as an important modulator in RA development, no clear evidence has been provided. In this study, we found that synovial fluid basic FGF (bFGF) concentration was significantly higher in RA than in osteoarthritis (OA) patients. bFGF stimulates proliferation and migration of human fibroblast-like synoviocytes (FLSs) by activation of the bFGF-FGF receptor 3 (FGFR3)-ribosomal S6 kinase 2 (RSK2) signaling axis. Moreover, a molecular docking study revealed that kaempferol inhibited FGFR3 activity by binding to the active pocket of the FGFR3 kinase domain. Kaempferol forms hydrogen bonds with the FGFR3 backbone oxygen of Glu555 and Ala558 and the side chain of Lys508. Notably, the inhibition of bFGF-FGFR3-RSK2 signaling by kaempferol suppresses the proliferation and migration of RA FLSs and the release of activated T-cell-mediated inflammatory cytokines, such as IL-17, IL-21, and TNF-α. We further found that activated phospho-FGFR3 and -RSK2 were more highly observed in RA than in OA synovium. The hyperplastic lining and sublining lymphoid aggregate layers of RA synovium showed p-RSK2-expressing CD68⁺ macrophages with high frequency, while pRSK2-expressing CD4⁺ T-cells was observed at a lower frequency. Notably, kaempferol administration in collagen-induced arthritis mice relieved the frequency and severity of arthritis. Kaempferol reduced osteoclast differentiation in vitro and in vivo relative to the controls and was associated with the inhibition of osteoclast markers, such as tartrate-resistant acid phosphatase, integrin β3, and MMP9. Conclusively, our data suggest that bFGF-induced FGFR3-RSK2 signaling may play a critical role during the initiation and progression of RA in terms of FLS proliferation and enhanced osteoclastogenesis, and that kaempferol may be effective as a new treatment for RA.

Inhibitory Effects of Dimethyllirioresinol, Epimagnolin A, Eudesmin, Fargesin, and Magnolin on Cytochrome P450 Enzyme Activities in Human Liver Microsomes

Magnolin, epimagnolin A, dimethyllirioresinol, eudesmin, and fargesin are pharmacologically active tetrahydrofurofuranoid lignans found in Flos Magnoliae. The inhibitory potentials of dimethyllirioresinol, epimagnolin A, eudesmin, fargesin, and magnolin on eight major human cytochrome P450 (CYP) enzyme activities in human liver microsomes were evaluated using liquid chromatography-tandem mass spectrometry to determine the inhibition mechanisms and inhibition potency. Fargesin inhibited CYP2C9-catalyzed diclofenac 4′-hydroxylation with a K_i value of 16.3 μM, and it exhibited mechanism-based inhibition of CYP2C19-catalyzed [S]-mephenytoin 4′-hydroxylation (K_i, 3.7 μM; k_inact, 0.102 min⁻¹), CYP2C8-catalyzed amodiaquine N-deethylation (K_i, 10.7 μM; k_inact, 0.082 min⁻¹), and CYP3A4-catalyzed midazolam 1′-hydroxylation (K_i, 23.0 μM; k_inact, 0.050 min⁻¹) in human liver microsomes. Fargesin negligibly inhibited CYP1A2-catalyzed phenacetin O-deethylation, CYP2A6-catalyzed coumarin 7-hydroxylation, CYP2B6-catalyzed bupropion hydroxylation, and CYP2D6-catalyzed bufuralol 1′-hydroxylation at 100 μM in human liver microsomes. Dimethyllirioresinol weakly inhibited CYP2C19 and CYP2C8 with IC₅₀ values of 55.1 and 85.0 μM, respectively, without inhibition of CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, and CYP3A4 activities at 100 μM. Epimagnolin A, eudesmin, and magnolin showed no the reversible and time-dependent inhibition of eight major CYP activities at 100 μM in human liver microsomes. These in vitro results suggest that it is necessary to investigate the potentials of in vivo fargesin-drug interaction with CYP2C8, CYP2C9, CYP2C19, and CYP3A4 substrates.

Magnolin inhibits prostate cancer cell growth in vitro and in vivo

BACKGROUND

Magnolin is the most active ingredient in the herb Magnolia fargesii, which has been traditionally used in oriental medicine to treat headaches and nasal congestion. Recent researches demonstrate that Magnolin inhibits cancer cell migration and invasion.

MATERIALS AND METHODS

This study used cell culture and the BALB/c nu/nu mouse xenograft model to investigate whether or not magnolin can inhibit the growth of PC3 and Du145 prostate cancer cells. MTT assay and flow cytometry were performed to estimate the proliferation, cycle, and apoptosis of the cells in vitro. Clone formation assay was also conducted. In the animal study, Ki-67 immunostaining and TUNEL assay were carried out to evaluate cell proliferation and apoptosis, respectively. To elucidate the possible mechanism by which magnolin attenuates prostate cancer cell growth, we estimated the expression levels of Akt/p-Akt, P53, P21, BCL-2, and cleaved Caspase3 by using Western blot 48h after magnolin-treatment of the cells.

RESULTS

Magnolin inhibited the proliferation and viability of the tumor cells by triggering cell cycle arrest via P53/P21 activation and inducing apoptosis in vitro and in vivo. Magnolin downregulated the phosphorylation of Akt protein kinase and upregulated cleaved Caspase3 during anti-proliferation and pro-apoptosis.

CONCLUSION

Magnolin may be a novel medicine for prostate cancer therapy.

Kazinol-E is a specific inhibitor of ERK that suppresses the enrichment of a breast cancer stem-like cell population

Growing evidence shows that cancer stem-like cells (CSLCs) contribute to breast cancer recurrence and to its resistance to conventional therapies. The extracellular signal-regulated kinase (ERK) signaling pathway is a major determinant in the control of diverse cellular processes, including the maintenance of CSLCs. In this study, we found that Kazinol-E, an antioxidant flavan from Broussonetia kazinoki, decreased the CSLC population of a breast cancer cell line, MCF7. The CSLC population, characterized by CD44 high/CD24 low expression or by high Aldehyde dehydrogenase 1 activity, was decreased by a concentration of Kazinol-E that did not affect the growth of bulk-cultured MCF7 cells. Kazinol-E did not decrease EGF-induced ERK phosphorylation in CSLCs, but did block the phosphorylation of an ERK substrate, p90RSK2, at Thr359/Ser363. We further demonstrated that EGF-induced ERK activity was blocked by Kazinol-E in a wild-type K-Ras-expressing non-small cell lung cancer cell line H226B. An in vitro kinase assay with purified ERK1 and p90RSK2 as its substrate demonstrated a direct inhibition of ERK activity by Kazinol E. Additionally, a the molecular docking study provided putative binding modes of Kazinol-E into the ATP binding pocket of ERK1 Collectively, these results suggest that Kazinol-E is a direct inhibitor of ERK1, and more studies are warranted to develop this reagent for therapeutic breast CSLC targeting.

Glabridin arrests cell cycle and inhibits proliferation of hepatocellular carcinoma by suppressing braf/MEK signaling pathway

Glabridin, an isoflavone isolated from licorice, owns a variety of pharmacological effects. Several reports have demonstrated that glabridin could regulate multiple cellular signaling pathways to inhibit the progression of cancer. However, the target proteins have not been elucidated yet. We used shape screening and induced fit docking to screen the protein data bank against glabridin. Braf and MEK1/2, important intermediate molecules of the braf/MEK cascade, were identified as the potential targets of glabridin. The experimental data showed that glabridin could inhibit the phosphorylation of MEK1/2 and the phosphorylation levels of downstream molecules including ERK1/2 and transcription factors ATF1 and CREB, but had no effect on the phosphorylation of braf. In particular, the in vitro pull-down assay indicated that glabridin selectively bound to braf and MEK1/2. What is more, exposure to glabridin significantly suppressed the proliferation of hepatocellular carcinoma HepG2 cell line. In addition, glabridin might arrest cell cycle in G1 through downregulation of cyclinD3, CDK2, and CDK4. In conclusion, glabridin is a potential multi-molecule-targeting inhibitor in the field of clinical prevention or treatment of cancer.

Analysis of the ways and methods of signaling pathways in regulating cell cycle of NIH3T3 at transcriptional level

BACKGROUND

To analyze the ways and methods of signaling pathways in regulating cell cycle progression of NIH3T3 at transcriptional level, we modeled cell cycle of NIH3T3 and found that G1 phase of NIH3T3 cell cycle was at 5-15 h after synchronization, S phase at 15-21 h, G2 phase at 21-22 h, M phase at 22-25 h.

RESULTS

Mouse Genome 430 2.0 microarray was used to detect the gene expression profiles of the model, and results showed remarkable changes in the expressions of 64 cell cycle genes and 960 genes associated with other physiological activity during the cell cycle of NIH3T3. For the next step, IPA software was used to analyze the physiological activities, cell cycle genes-associated signal transduction activities and their regulatory roles of these genes in cell cycle progression, and our results indicated that the reported genes were involved in 17 signaling pathways in the regulation of cell cycle progression. Newfound genes such as PKC, RAS, PP2A, NGR and PI3K etc. belong to the functional category of molecular mechanism of cancer, cyclins and cell cycle regulation HER-2 signaling in breast cancer signaling pathways. These newfound genes could promote DNA damage repairment and DNA replication progress, regulate the metabolism of protein, and maintain the cell cycle progression of NIH3T3 modulating the reported genes CCND1 and C-FOS.

CONCLUSION

All of the aforementioned signaling pathways interacted with the cell cycle network, indicating that NIH3T3 cell cycle was regulated by a number of signaling pathways.

The potential for chemical mixtures from the environment to enable the cancer hallmark of sustained proliferative signalling

The aim of this work is to review current knowledge relating the established cancer hallmark, sustained cell proliferation to the existence of chemicals present as low dose mixtures in the environment. Normal cell proliferation is under tight control, i.e. cells respond to a signal to proliferate, and although most cells continue to proliferate into adult life, the multiplication ceases once the stimulatory signal disappears or if the cells are exposed to growth inhibitory signals. Under such circumstances, normal cells remain quiescent until they are stimulated to resume further proliferation. In contrast, tumour cells are unable to halt proliferation, either when subjected to growth inhibitory signals or in the absence of growth stimulatory signals. Environmental chemicals with carcinogenic potential may cause sustained cell proliferation by interfering with some cell proliferation control mechanisms committing cells to an indefinite proliferative span.

Magnolin inhibits cell migration and invasion by targeting the ERKs/RSK2 signaling pathway

BACKGROUND

Magnolin is a natural compound abundantly found in Magnolia flos, which has been traditionally used in oriental medicine to treat headaches, nasal congestion and anti-inflammatory reactions. Our recent results have demonstrated that magnolin targets the active pockets of ERK1 and ERK2, which are important signaling molecules in cancer cell metastasis. The aim of this study is to evaluate the effects of magnolin on cell migration and to further explore the molecular mechanisms involved.

METHODS

Magnolin-mediated signaling inhibition was confirmed by Western blotting using RSK2(+/+) and RSK2(-/-) MEFs, A549 and NCI-H1975 lung cancer cells, and by NF-κB and Cox-2 promoter luciferase reporter assays. Inhibition of cell migration by magnolin was examined by wound healing and/or Boyden Chamber assays using JB6 Cl41 and A549 human lung cancer cells. The molecular mechanisms involved in cell migration and epithelial-to-mesenchymal transition were determined by zymography, Western blotting, real-time PCR and immunocytofluorescence.

RESULTS

Magnolin inhibited NF-κB transactivation activity by suppressing the ERKs/RSK2 signaling pathway. Moreover, magnolin abrogated the increase in EGF-induced COX-2 protein levels and wound healing. In human lung cancer cells such as A549 and NCI-H1975, which harbor constitutive active Ras and EGFR mutants, respectively, magnolin suppressed wound healing and cell invasion as seen by a Boyden chamber assay. In addition, it was observed that magnolin inhibited MMP-2 and -9 gene expression and activity. The knockdown or knockout of RSK2 in A549 lung cancer cells or MEFs revealed that magnolin targeting ERKs/RSK2 signaling suppressed epithelial-to-mesenchymal transition by modulating EMT marker proteins such as N-cadherin, E-cadherin, Snail, Vimentin and MMPs.

CONCLUSIONS

These results demonstrate that magnolin inhibits cell migration and invasion by targeting the ERKs/RSK2 signaling pathway.