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Kinase inhibitors reduce 7,12-dimethylbenz a anthracene-induced onco-suppressor gene expression in short-term experiments
Abstract
Aims. Elevated expression of oncogenes and tumour suppressor genes after treatment with 7,12- dimethylbenz[a]anthracene (DMBA) as early markers of carcinogenesis has been previously observed. The potential antineoplastic and chemopreventive properties of four protein tyrosine kinase (PTK) inhibitor molecules were studied. Materials and methods. In order to determine whether a promising antineoplastic activity would extend to anticarcinogenic properties, the effects of these molecules on the 7,12 DMBA-induced expression of Ha-ras oncogene and p53 tumour suppressor genes in the liver, lungs, bone marrow and kidney of CBA/Ca inbred mice was investigated. The experimental molecules were administered (I) 24 hours prior to, (II) simultaneously with, or (III) 24 hours after DMBA exposure. Results. PTK inhibitor (1Z)-1-(3,4-Dihy-droxybenzylidene)-3,4-dihydro[1,4]oxazino[3,4-b]quinazolon-6(1H)-on and N-(3-bromophenyl)-6,7-dimethoxy quinazolin-4-amine reduced the expression of Ha-ras and p53 genes in all of the examined organs in the different treated groups. Another two PTK inhibitor, 2-Benzyl-1-(4-hydroxyphenyl)-3-me-thyl-2,3-dihydroimi-dazo[5,1-b]quinazolin-9(1H)-one and 2-[(2E)-2-(3,4-dihydroxybenzylidene)hydrazino]-N-(3-nitrophenyl)-2-oxoacetamide reduced both Haras and p53 gene expression induced by DMBA in all of the examined organs (except for the kidneys, where only Ha-ras expression decreased) in all of the experimental settings. Conclusions. Our in vivo short-term experimental results provide some evidence, that PTK inhibitors exhibit antineoplastic and chemopre-ventive effects by reversing the overexpression of the early markers of carcinogenesis. This early molecular biomarker model indicates the first steps of malignant transformation at subcellular level and possible anti-tumour effects, as well.
... DMBA is a widely used polycyclic aromatic hydrocarbon chemical carcinogen that initiates chemical carcinogenesis by inducing various oncogenic mutations resulting in lung tumor, squamous cell carcinoma, and vascular tumors (hemangiomas), as well as intestinal, mammary, uterine, or hematologic tumors [41,42]. The results suggested that chalcone analogues, as intermediary compounds of the flavonoid biosynthetic pathway, and plant derivatives may possess potential chemopreventive effects [43]. ...
Tyrosine kinases play crucial roles in cellular development and tumorigenesis. Tyrosine kinase inhibitors (TKIs) are effective and widely used drug molecules in targeted cancer therapies. Altered expressions of protooncogenes and tumor suppressor genes after DMBA (7,12-dimethylbenz[a]anthracene) treatment have been described as early markers of tumor induction; however their tissue-specific effects remain still unclear. Our study was aimed at examining the short-term possible antineoplastic and chemopreventive effects of a TKI compound (imatinib mesylate) on a DMBA-induced mouse tumor model. In addition, we also investigated the tissue-specific expressions of Hras, Kras, Myc, and Trp53 genes in the brain, bone marrow, spleen, liver, abdominal lymph nodes, thymus, lungs, and kidneys, respectively. 24 hours after the imatinib mesylate injection, we observed significant Kras downregulation in the bone marrow and lung of the DMBA-treated mice. Moreover, the mRNA expression of Myc was also found to be decreased significantly in the spleen. Interestingly, while Trp53 expression was significantly increased in the lung, it was decreased in the other tissues. However, there was also a tendency in the decreased Myc level in the bone marrow, brain, kidneys, lungs, and lymph nodes and in the decreased Hras level in the bone marrow, kidneys, and lungs, although no significant differences were observed. Our findings indicate rapid tissue-specific impact of imatinib mesylate on DMBA-induced gene expression in vivo, supporting the chemopreventive potential of imatinib mesylate in cancer.
The cytochrome P450 enzymes are of great importance and interest because they catalyze reactions which have profound effects on the biological activities of drugs, environmental chemistry, and endogenous compounds. As a consequence, the literature on these enzymes is too voluminous to read, scan, or even cite. And while the pace accelerates and the scope broadens to include more biochemical aspects such as amino acid sequencing and three-dimensional structural models of isoenzymes, the bench scientists struggles to perceive where the new information fits and what applicability it has, if any, zo his/her work. Pharmacologists and toxicologists also feel swamped by the exponential increase in cytochrome P450 publications. The present paper is designed to assist by providing a framework for the prediction and interpretation of new data. It is an effort to summarize the functions of known human cytochrome P450s in terms of their specific catalytic activities, substrates, inducers, and inhibitors. Summaries are presented in tables for ready access of information. (Tables 5-21) The literature through 1996 is covered in the reference section. In some instances, references are to reviews that should be consulted for citations of the original literature.
(Full text of the paper available through Informa Healthcare Publisher only, or download updated article: Summary of information on human CYP enzymes: human P450 metabolism data. Drug Metabolism Reviews 01/2002; 34(1-2):83-448.)
Although induced pluripotent stem cells (iPSCs) hold great promise for customized regenerative medicine, the molecular basis of reprogramming is largely unknown. Overcoming barriers that maintain cell identities is a critical step in the reprogramming of differentiated cells. Since microRNAs (miRNAs) modulate target genes tissue-specifically, we reasoned that distinct mouse embryonic fibroblast (MEF)-enriched miRNAs post-transcriptionally modulate proteins that function as reprogramming barriers. Inhibiting these miRNAs should influence cell signaling to lower those barriers. Here we show that depleting miR-21 and miR-29a enhances reprogramming efficiency in MEFs. We also show that the p53 and ERK1/2 pathways are regulated by miR-21 and miR-29a and function in reprogramming. In addition, we provide the first evidence that c-Myc enhances reprogramming partly by repressing MEF-enriched miRNAs, such as miR-21 and miR-29a. Our results demonstrate the significance of miRNA function in regulating multiple signaling networks involved in iPSC generation. These studies should facilitate development of clinically applicable reprogramming strategies.
A long-term experimental animal model was developed by our research group for the evaluation of potential chemopreventive effects. The inhibitory effects of agents on carcinogen (7,12-dimethylbenz[a]anthracene (DMBA) induced molecular epidemiological biomarkers, in this case the expression of key onco/suppressor genes were investigated.
The expression pattern of c-myc, Ha-ras, Bcl-2, K-ras protooncogene and p53 tumour suppressor gene were studied to elucidate early carcinogenic and potential chemopreventive effects. The consumption of so-called Claw of Dragon tea (CoD™ tea) containing the bark of Uncaria guianensis, Cat's Claw (Uncaria sp. U. tomentosa) and Palmer trumpet-tree (Tabebuia sp. T. avellanedae) was able to decrease the DMBA-induced onco/suppressor gene overexpression in a short-term animal experiment. In a following study CBA/Ca mice were treated with 20 mg/kg bw DMBA intraperitoneally (i.p.) and the expression patterns of onco/suppressor genes were examined at several time intervals. According to the examined gene expression patterns in this long-term experiment the chemopreventive effect of CoD™ tea consumption could be confirmed. Copyright
Hemangioblastomas frequently develop in patients with von Hippel-Lindau (VHL) disease, an autosomal dominant genetic disorder. The tumors are characterized by a dense network of blood capillaries, often in association with cysts. Although activation of receptor tyrosine kinase (RTK) signaling, including epidermal growth factor receptor (EGFR) has been implicated in the development of malignant brain tumors such as high-grade gliomas, little is known about the role of RTK signaling in hemangioblastomas. To address this issue, we examined hemangioblastoma tumor specimens using receptor tyrosine kinase (RTK) activation profiling and immunohistochemistry. Six human hemangioblastomas were analyzed with a phospho-RTK antibody array, revealing EGFR phosphorylation in all tumors. EGFR expression was confirmed by immunohistochemistry in all tumors analyzed and downstream effector pathway activation was demonstrated by positive staining for phospho-AKT. Our findings suggest that, in primary hemangioblastomas, RTK upregulation and signaling predominantly involves EGFR, providing an attractive molecular target for therapeutic intervention.
Signaling Pathways in Liver Diseases, 2nd edition focuses on signaling pathways which are particularly important in liver diseases. Recent progress brought hepatology to new frontiers. The increasing frequency of surgery on steatotic and cirrhotic liver obliges liver surgeons and hepatologists to understand the molecular mechanisms at play in these situations and how they can be influenced. Better comprehension of the cellular mechanisms participating in liver regeneration, hepato-cellular apoptosis and ischemia/reperfusion inquiry is mirrored by a dramatic increase in complexity. The number and scope of publications is intimidating and difficult for busy individuals to extract a coherent framework. This book will serve as a source of information facilitating the reading of the literature and the planning of trials. Translational medicine implies knowledge of the molecular targets for novel therapeutic strategies. It will furthermore stimulate more research and lead to better exchange between the laboratory, the clinical ward and the operation room.
1-Benzylidene (2-14) and 1-phenylhydrazono derivatives (15-29) of 3,4-dihydro-1H,6H-[1,4]oxazino[3,4-b]quinazolin-6-one (1) were obtained from the condensation reactions of 1 with a series of aromatic aldehydes and by direct diazonium coupling with aryl-diazonium chlorides. The substances were tested for their ability to inhibit the tyrosine kinase activity of SW-620 (human colon carcinoma) cells. Compounds 8, 10, 12, and 13 showed remarkable inhibitory activity. Copyright (C) 1996 Elsevier Science Ltd
To obtain insight into the cancer progression and metastatic process, we evaluate p53/epidermal growth factor receptor (EGFR) somatic aberrations in non-small-cell lung cancers to compare accumulated genetic alterations between primary tumors and lymph node metastases.
A total of 56 primary lung cancers with corresponding lymph node metastases were identified to investigate somatic mutations and altered expressions of p53 and EGFR for clonality assessment. Genomic DNA was extracted from macrodissected cells of paraffin-embedded primary tumor and metastatic lymph node tissues. Overexpression and somatic mutations in exons of p53 (exons 5-8) and tyrosine kinase domain of EGFR (exons 18-21) were examined by immunohistochemical staining and DNA sequencing, respectively.
p53 and EGFR mutation/overexpression status were different between primary tumors and lymph node metastases in 5.4/7.2% and 28.6/33.9%, respectively. In most cases, the p53 and EGFR mutations usually preceded lymph node metastasis, and these gene statuses in the primary cancer and their lymph node metastasis were concordant (92.9 and 69.6%, respectively), which further supported the hypothesis that when these p53 mutations occur before the establishment of lymph node metastasis, they subsequently persist in the metastatic nodes. The expressions of p53 and EGFR showed 7.1 and 33.9% discordance in that order.
Our results reveal that p53 and EGFR mutations usually precede lymph node metastasis. The higher prevalence of EGFR heterogeneity existing in the primary tumor is not reflected in all lymph node metastasis and thus might have therapeutic implications when adjuvant therapy is considered.
Oridonin was reported to induce L929 cell apoptosis via ROS-mediated mitochondrial and ERK pathways; however, the precise mechanisms by which oridonin induces cell death remain unclear. Herein, we found that oridonin treatment induced an increase in G(2)/M phase cell percentage. And, G(2)/M phase arrest was associated with down-regulation of cell cycle related cdc2, cdc25c and cyclinB levels, as well as up-regulation of p21 and p-cdc2 levels. In addition, we discovered that interruption of p53 activation decreased oridonin-induced apoptosis, and blocking ERK by specific inhibitors or siRNA suppressed oridonin-induced p53 activation. Moreover, inhibition of PTK, protein kinase C, Ras, Raf or JNK activation increased oridonin-induced apoptosis. Also, the level of Ras, Raf or JNK was down-regulated by oridonin, and the inhibition of PTK, Ras, Raf activation decreased p-JNK level. In conclusion, oridonin induces L929 cell G(2)/M arrest and apoptosis, which is regulated by promoting ERK-p53 apoptotic pathway and suppressing PTK-mediated survival pathway.