Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We recently reported a diurnal and norepinephrine (NE) -induced expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) in the rat pineal gland and postulated that this MKP-1 expression might impact adrenergic-regulated arylalkylamine-N-acetyltransferase (AA-NAT) activity via modulation of MAPKs. In this study, we investigated the effect of depletion of MKP-1 expression by using doxorubicin, a topoisomerase inhibitor that suppresses the expression of MKP-1 in other cell types and small interfering RNA targeted against Mkp1 in NE-stimulated pinealocytes. We found that both treatments were effective in inhibiting NE induction of MKP-1 expression. Moreover, both treatments also resulted in a prolonged activation of p42/44MAPK and an increase in AA-NAT induction by NE. In contrast, treatment of pinealocytes with PD98059, an inhibitor of MAPK kinase, reduced NE-stimulated AA-NAT activity. Interestingly, suppressing MKP-1 expression had no effect on the time profile of NE-stimulated p38MAPK activation. These results indicate that MKP-1 modulates the profile of AA-NAT activity by selectively shaping the activation profile of p42/44MAPK but not that of p38MAPK.
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PMID:Mitogen-activated protein kinase phosphatase-1 (MKP-1) preferentially dephosphorylates p42/44MAPK but not p38MAPK in rat pinealocytes. 1743 49

Natural products represent a rich reservoir of potential small chemical molecules exhibiting antiproliferation and anticancer properties. An example is berberine, a protoberberine alkaloid widely distributed in medical plants used in traditional Chinese prescriptions. Recent advances have shown that berberine exerts anticancer activities both in vitro and in vivo through different mechanisms. Berberine shows inhibitory effects on the proliferation and reproduction of certain tumorigenic microorganisms and viruses, such as Heliobacter pylori and hepatitis B virus. Transcriptional regulation of some oncogene and carcinogenesis-related gene expression and interaction with both DNA and RNA are also well documented. Besides, berberine is a broad spectrum enzyme inhibitor, which affects N-acetyltransferase, cyclooxygenase-2, and topoisomerase activities and gene/protein expression. These actions, together with the regulation of reactive oxygen species production, mitochondrial transmembrane potential, and nuclear factor-kappaB activation might underlie its antiproliferative and proapoptotic effects. More importantly, the suppression of tumor growth and metastasis, the beneficial application in combined medication, and the improvement of multidrug resistance both in vivo and in vitro clearly show its potential as an alternative medicine for tumor chemotherapy.
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PMID:A systematic review of the anticancer properties of berberine, a natural product from Chinese herbs. 1970 71

Gastrointestinal cancers are among the most prevalent cancers in the general population. Despite effective early diagnostics and intervention, the gastrointestinal cancer-related mortality still remains elevated. Berberine (BBR) is a benzyl tetra isoquinoline alkaloid exracted from several plants. BBR is nontoxic to human normal cells, but suppresses the growth of different tumor cells: melanoma, epidermoid carcinoma, hepatoma, oral carcinoma, glioblastoma, prostatic carcinoma, and gastric carcinoma. In particular, BBR seems to suppress the proliferation of gastrointestinal cancers in a number of preclinical models. Several mechanisms of action have been hypothesized and demonstrated: immunomodulation, inhibition of topoisomerase enzymes, suppression of the EGF receptor, Her2/neu, and the VEGF receptor, induction of p53, Cip1/p21, Kip1/p27, Rb expression, induction of apoptosis (by regulation of MMPs pathway, caspases, Bax, and Smac/DIABLO), inhibition of arylamin N-acetyltransferase activity, and regulation of microRNAs expression. The aim of this review is to summarize the pharmacological effects of BBR on animal and human gastrointestinal cancers.
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PMID:Berberine: A potential adjunct for the treatment of gastrointestinal cancers? 3012 74