Antitumor Efficacy of Hypothemycin, A New Ras‐signaling Inhibitor

Tanaka, Hidekazu; Nishida, Kazuyo; Sakai, Kenji; Yoshioka, Takayuki

doi:10.1111/j.1349-7006.1999.tb00688.x

Cited by 60 publications

(39 citation statements)

References 27 publications

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“…18) On the other hand, hypothemycin, which inhibits Ras-mediated cellular signaling, was found to reduce the transcription of Ras-inducible genes, MMP-1, MMP-3, MMP-9, TGF-β, and VEGF. 19) Further molecular analysis of transcription factors is required for a better understanding of the inhibitory effect of nobiletin on MMPs.…”

Section: Discussionmentioning

confidence: 99%

The Citrus Flavonoid, Nobiletin, Inhibits Peritoneal Dissemination of Human Gastric Carcinoma in SCID Mice

Minagawa¹,

Otani²,

Kubota³

et al. 2001

Japanese Journal of Cancer Research

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The flavonoid nobiletin (5,6,7,8,3′ ′ ′ ′,4′ ′ ′ ′-hexamethoxyflavone), found in Citrus depressa Rutaceae, a popular citrus fruit in Okinawa, Japan, reportedly inhibits the production of pro-matrix metalloproteinase (proMMP)-1, 3, and 9 in rabbit synovial fibroblasts in vitro. In the present study, we demonstrated the inhibitory effects of nobiletin on the proliferation of the cancer cell line, TMK-1, and its production of MMPs. In the SCID mouse model, we found that nobiletin inhibited the formation of peritoneal dissemination nodules from TMK-1. The enzymatic activity of MMP-9 expressed in culture medium obtained from a co-culture of TMK-1 and mouse fibroblastic cells was inhibited by nobiletin in a concentration-dependent manner. In the SCID mouse model, total weight of dissemination nodules was significantly lower in the treated group compared with the vehicle control group (0.07 g vs. 0.78 g, P = = = =0.0059). The total number of dissemination nodules was also significantly lower than in the vehicle control group (7.5 vs. 69.3/body, P = = = =0.0001). These results suggest that nobiletin may be a candidate anti-metastatic drug for prevention of peritoneal dissemination of gastric cancer. Key words: Flavonoid -Nobiletin -Gastric cancer -Peritoneal dissemination -Matrix metalloproteinaseIn spite of the general decline in gastric cancer rates, this cancer remains one of the most important causes of death among Japanese people. In particular, peritoneal dissemination at the final stage of gastric cancer remains untreatable. Although several trials have attempted to control peritoneal dissemination of gastric cancer by chemotherapy and hyperthermia, no significant prolongation of survival was found. Peritoneal dissemination involves several steps, including tumor cell attachment, invasion and growth in the peritoneum. We investigated the role of matrix metalloproteinases (MMPs) in the invasion and metastasis of gastric cancer, and found a close relationship between MMPs expression and malignant potential of gastric cancer.1, 2) We postulated that an appropriate inhibitor of MMP could prevent peritoneal dissemination by controlling the initial steps, and demonstrated a preventive effect of the MMP inhibitor R-94138 in a peritoneal dissemination model using the human gastric cancer cell line TMK-1 in nude mice.3)The intake of citrus fruits is considered beneficial for health, and in a recent literature review of citrus flavonoids, a broad spectrum of biological activities including anti-carcinogenic and antitumor activities was discussed. It is commonly accepted that cancer formation can be prevented by the ingestion of certain foods, 4) and flavonoids in citrus fruits and juices are among the most prominent cancer-preventing agents. Epidemiological studies have indicated that flavonoid ingestion is associated with a reduced risk of certain forms of cancer. 5) Nobiletin (5,6,7,8,3′, is a polymethoxyflavonoid extracted from Citrus depressa Hayata (Rutaceae), a popular citrus fruit in Okinawa, Japan. Nobiletin is kn...

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Section: Discussionmentioning

confidence: 99%

The Citrus Flavonoid, Nobiletin, Inhibits Peritoneal Dissemination of Human Gastric Carcinoma in SCID Mice

Minagawa¹,

Otani²,

Kubota³

et al. 2001

Japanese Journal of Cancer Research

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“…TF323-C3 cells were cotransfected with pSEAP-RP4.1 mixed with pUCSV-BSD [ratio (w/w) = 4:1] followed by selection in growth medium containing 8 µg/ml blasticidine-S. A clone (named YM3) that showed highest degree of SEAP up-regulation (see below for SEAP assay) after Dox-treatment was selected. SEAP was also up-regulated in YM3 cells after treatment with hypothemycin (1 µg/ml), a MEK inhibitor inducing flat reversion in v-K-ras-transformed cells [48,49]. To establish an indicator cell line for assessing antitumorigenic and anit-metastatic activities of a drug in vivo, RZmet3 cells were co-transfected with pGL4 (contaning Photinus pyralis luciferase gene; Promega) mixed with pcDNA3.1(-)-Hygro (Invitrogen), followed by selection in growth medium containing hygromycin-B (400 U/ml).…”

Section: Establishments Of Indicator Cellsmentioning

confidence: 99%

A novel screen using the Reck tumor suppressor gene promoter detects both conventional and metastasis-suppressing anticancer drugs

et al. 2010

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AbstrAct:The membrane-anchored matrix metalloproteinase-regulator RECK is often downregulated in various types of cancers; the levels of residual RECK in resected tumors often correlate with better prognosis. Forced expression of RECK in cancer cells suppresses tumor angiogenesis, invasion, and metastasis in xenograft models. RECK is therefore a promising marker for benignancy and a potential effector in cancer therapy. We established a cell line containing two transgene systems: (1) the secreted alkaline phosphatase (SEAP) gene fused to Reck promoter and (2) the HRAS 12V oncogene driven by the Tet-off promoter system. This cell line exhibits transformed phenotype in regular medium and flat morphology with increased SEAP activity in the presence of doxycycline, allowing the assessment of RECK-inducing activity of chemicals in the contexts of both transformed and untransformed cells. Our pilot experiments with 880 known bioactive compounds detected 34 compounds that activate RECK promoter; among these, 10 were authentic anticancer drugs. Four selected compounds up-regulated endogenous RECK protein in several human cancer cell lines. The top-ranking compound, disulfiram, strongly suppressed spontaneous lung-metastasis of human fibrosarcoma cells in nude mice. Our data demonstrate the value of this screen in discovering effective cancer therapeutics.

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“…10) Hypothemycin also has been shown to reverse rasmediated transformation. 3,4) We compared the effects of hypothemycin with those of two MEK inhibitors, U0126 and PD98059; we focused on the morphology and anchorage-independent growth of Ki-ras/NRK cells. Treatment of Ki-ras/ NRK with 2 mM hypothemycin caused distinct morphological reversion to a flat, normal appearance (Fig.…”

Section: Hypothemycin Normalizes Growth Properties Of Kiras-transformmentioning

confidence: 99%

“…1), a RAL containing a cis-enone moiety that initially did not reveal any particularly interesting activity, was later shown to inhibit ras-transformation and T cell activation. [2][3][4] Hypothemycin and other closely related cis-enone RALs gained attention as compounds that irreversibly inhibit certain protein kinases such as mitogen-activated protein kinase kinase (MEK), extracellular signalf-regulated kinase (ERK) and TAK1, but not RAF, protein kinase C (PKC) or protein kinase A (PKA). [5][6][7][8] From their structures and irreversible mode of action, cis-enone RALs were predicted to form stable Michael addition products with cysteine residues of protein kinases.…”

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confidence: 99%

The Resorcylic Acid Lactone Hypothemycin Selectively Inhibits the Mitogen-Activated Protein Kinase Kinase-Extracellular Signal-Regulated Kinase Pathway in Cells

Fukazawa

Ikeda

Fukuyama

et al. 2010

Biological & Pharmaceutical Bulletin

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Resorcylic acid lactones (RALs) constitute a family of polyketide mycotoxins with a variety of biological activities.1) Representative examples are the heat shock protein 90 inhibitor radicicol and the estrogen agonist zearalenone. Hypothemycin ( Fig. 1), a RAL containing a cis-enone moiety that initially did not reveal any particularly interesting activity, was later shown to inhibit ras-transformation and T cell activation. [2][3][4] Hypothemycin and other closely related cis-enone RALs gained attention as compounds that irreversibly inhibit certain protein kinases such as mitogen-activated protein kinase kinase (MEK), extracellular signalf-regulated kinase (ERK) and TAK1, but not RAF, protein kinase C (PKC) or protein kinase A (PKA). [5][6][7][8] From their structures and irreversible mode of action, cis-enone RALs were predicted to form stable Michael addition products with cysteine residues of protein kinases. Bioinformatics studies revealed that a cysteine residue that immediately precedes the highly conserved Asp-Phe-Gly (DFG) motif is the cis-enone RAL binding site.9) This cysteine is conserved in 9% (46/ 510) of the protein kinases in the human kinome.Although different kinases contain the RAL target cysteine, cis-enone RALs have been isolated as selective inhibitors of MEK. 7,8) Furthermore, cis-enone RALs share various biological properties with MEK inhibitors. Sonoda et al. identified hypothemycin as a ras-signaling inhibitor.3) We reported that the MEK inhibitor U0126 reverses ras-mediated transformation.10) Hypothemycin and MEK inhibitors showed strong activity in cell lines with the activating BRAF V600E mutation.11) Sonoda et al. reported that the suppression of ras-induced transformation was associated with accelerated cyclin D1 degradation, 3) and a MEK inhibitor caused a loss of cyclin D expression in BRAF mutants. 11)Here, we compared the effects of hypothemycin and MEK inhibitors on signaling pathways in cells. Our results show that even though the RAL target cysteine is not confined to the components of the MEK-ERK pathway, in cellular settings hypothemycin preferentially blocks the MEK-ERK axis with sufficient selectivity to impair transformed phenotypes of cancer cells requiring this pathway. The resorcylic acid lactone hypothemycin has been shown to inactivate protein kinases by binding to a cysteine conserved in 46 protein kinases, including mitogen-activated protein kinase kinase (MEK), extracellular signal-regulated kinase (ERK) and platelet-derived growth factor receptor (PDGFR). We assessed the selectivity of hypothemycin in cellular contexts. Hypothemycin normalized the morphology and inhibited anchorage-independent growth of Ki-ras transformed normal rat kidney (NRK) cells with selectivity and potency comparable to or greater than that of the MEK inhibitor U0126. In Ki-ras-transformed and phorbol 12-myristate 13-acetate (PMA)-treated NRK cells, hypothemycin blocked ERK activation but showed a minimal effect on autophosphorylation of protein kinase D1 (PKD1), another kinase contain...

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Antitumor Efficacy of Hypothemycin, A New Ras‐signaling Inhibitor

Abstract: We have devised a new drug screening assay to discover anti-cancer drugs which inhibit Ras-mediated cellular signals, by utilizing a Ras-responsive element (RRE)-driven reporter gene system. We found that hypothemycin, an anti-bacterial, reduces RRE-dependent transcription.

Cited by 60 publications

References 27 publications

The Citrus Flavonoid, Nobiletin, Inhibits Peritoneal Dissemination of Human Gastric Carcinoma in SCID Mice

The Citrus Flavonoid, Nobiletin, Inhibits Peritoneal Dissemination of Human Gastric Carcinoma in SCID Mice

A novel screen using the Reck tumor suppressor gene promoter detects both conventional and metastasis-suppressing anticancer drugs

The Resorcylic Acid Lactone Hypothemycin Selectively Inhibits the Mitogen-Activated Protein Kinase Kinase-Extracellular Signal-Regulated Kinase Pathway in Cells

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