Regulation and drug resistance mechanisms of mammalian ribonucleotide reductase, and the significance to DNA synthesis

1990 ◽  
Vol 68 (12) ◽  
pp. 1364-1371 ◽  
Author(s):  
Jim A. Wright ◽  
Arthur K. Chan ◽  
Bob K. Choy ◽  
Robert A. R. Hurta ◽  
Grant A. McClarty ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Drug Resistance ◽  
Dna Synthesis ◽  
Ribonucleotide Reductase ◽  
Cell Biology ◽  
De Novo ◽  
Mutant Cell ◽  
Resistance Mechanisms ◽  
M2 Protein ◽  
Iron Storage

Mammalian ribonucleotide reductase, which occupies a key position in the synthesis of DNA, is a highly controlled enzyme activity, because it is solely responsible-for the de novo reduction of ribonucleoside diphosphates to their corresponding deoxyribonucleoside diphosphate forms, required for DNA synthesis. Ribonucleotide reductase consists of two dissimilar protein components often called M1 and M2, which are independently regulated during cell proliferation. The M1 component contains multiple effector binding sites and is responsible for the complex allosteric regulation of the enzyme, whereas the M2 protein contains nonheme iron and a unique tyrosyl-free radical required for ribonucleotide reduction. Since the reaction is rate limiting for DNA synthesis, ribonucleotide reductase plays an important role in regulating cell division, and hence, cell proliferation. There are many inhibitors of ribonucleotide reductase and perhaps the most valuable one from a cell biology, biochemistry, and clinical point of view is the hydroxamic acid, hydroxyurea. This drug has also been very useful as a selective agent for isolating a variety of mammalian mutant cell lines altered in ribonucleotide reductase gene expression. Regulatory, structural, and biological characteristics of ribonucleotide reductase are reviewed, including evidence that ribonucleotide reductase, particularly the M2 protein, has an important early role to play in tumor promotion. In addition, modifications in the expressions of genes altered in hydroxyurea-resistant mutants and cultured in the absence or presence of hydroxyurea are discussed, with emphasis on changes in M2 protein, M1 protein, and the iron-storage protein ferritin. Several regulatory models are presented, including a model showing the relationships between M2 protein levels, deoxyribonucleotide pools, and DNA synthesis, and a model demonstrating a linkage between M2 and ferritin proteins in regulating DNA synthesis in normal and hydroxyurea-resistant mammalian cells.Key words: DNA synthesis, cell proliferation, ribonucleotide reductase, drug resistance.

Inhibition of mammalian ribonucleotide reductase by cis-diamminedichloroplatinum(II)

1992 ◽  
Vol 70 (12) ◽  
pp. 1332-1338 ◽  
Author(s):  
Christine S. M. Chiu ◽  
Arthur K. Chan ◽  
Jim A. Wright
Keyword(s):  
Drug Resistance ◽  
Ribonucleotide Reductase ◽  
Reductase Activity ◽  
Mutant Cell ◽  
Antitumor Agent ◽  
Resistance Mechanisms ◽  
Point Of View ◽  
Cytotoxic Action ◽  
Cytotoxic Effects ◽  
Ribonucleotide Reductase Activity

Ribonucleotide reductase is a highly regulated, rate-limiting activity in the synthesis of DNA. A previous study has shown that the Escherichia coli enzyme is inhibited by the clinically important antitumor agent cis-diamminedichloroplatinum(II) (DDP), and this has led to the hypothesis that ribonucleotide reductase is an important site of action for this chemotherapeutic agent. This hypothesis has been directly tested in this investigation. We observed that DDP inhibits the mammalian ribonucleotide reductase, with 50% inhibition occurring at 0.3 mM. Unlike the E. coli enzyme where only one of the two protein components is targeted by DDP, we observed that both of the mammalian proteins (R1 and R2) were sites for the inhibitory activity of the drug. Colony-forming experiments, enzyme activity studies, and analyses of R1 and R2 message levels in mutant cell lines containing either high levels of ribonucleotide reductase activity or exhibiting resistance to the cytotoxic effects of DDP were used to further investigate the potential role of ribonucleotide reductase in DDP cytotoxic action and drug resistance. These studies did not support a hypothesis formulated in the earlier investigation that inhibition of ribonucleotide reductase is an important component of DDP cytotoxic activity or that it is a major participant in DDP resistance mechanisms. From a biological point of view, DDP is a very active drug, and in addition to its cytotoxic effects it is capable of inducing a variety of cellular changes. Whether or not the inhibition of mammalian ribonucleotide reductase activity that we have described in this study plays a role in mediating any of these other effects remains to be determined.Key words: cisplatin, ribonucleotide reductase, drug resistance, hydroxyurea.

scholarly journals Inhibition of cell division by interferons. The relationship between changes in utilization of thymidine for DNA synthesis and control of proliferation in Daudi cells

1983 ◽  
Vol 214 (3) ◽  
pp. 983-990 ◽  
Author(s):  
D R Gewert ◽  
G Moore ◽  
M J Clemens
Keyword(s):  
Cell Proliferation ◽  
Dna Synthesis ◽  
Kinase Activity ◽  
Thymidine Incorporation ◽  
De Novo ◽  
Culture Conditions ◽  
Interferon Treatment ◽  
Daudi Cells ◽  
And Control ◽  
The Relationship

Inhibition of the proliferation of Daudi cells by exposure to human lymphoblastoid interferons is associated with an early and marked decrease in the incorporation into DNA of exogenous [3H]thymidine when cells are incubated with trace amounts of this precursor. In contrast, incorporation of exogenous deoxyadenosine into DNA is unchanged under the same conditions. Interferon treatment results in a lowering of thymidine kinase activity, an effect which may be largely responsible for the inhibition of incorporation of labelled thymidine into DNA. At higher concentrations of exogenous thymidine, which minimize the contribution of intracellular sources to the dTTP pool, the inhibition of thymidine incorporation is abolished. Under conditions in which exogenous thymidine is rigorously excluded from the medium or, conversely, in which cells are entirely dependent on exogenous thymidine for growth, the magnitude of the inhibition of cell proliferation by interferons is the same as under normal culture conditions. We conclude that, even though cell growth is impaired, the rate of DNA synthesis is not grossly inhibited up to 48 h after commencement of interferon treatment. Furthermore, changes in neither the utilization of exogenous thymidine nor the synthesis of nucleotides de novo are responsible for the effect on cell proliferation.

scholarly journals Primary cilia mediate diverse kinase inhibitor resistance mechanisms in cancer

2017 ◽  
Author(s):  
Andrew D. Jenks ◽  
Simon Vyse ◽  
Jocelyn P. Wong ◽  
Deborah Keller ◽  
Tom Burgoyne ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Primary Cilia ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
De Novo ◽  
Human Cancer ◽  
Structural Features ◽  
Resistance Mechanisms ◽  
Pathway Activation ◽  
Inhibitor Resistance

AbstractPrimary cilia are microtubule-based organelles that detect mechanical and chemical stimuli. Although cilia house a number of oncogenic molecules (including Smoothened, KRAS, EGFR, and PDGFR), their precise role in cancer remains unclear. We have interrogated the role of cilia in acquired andde novoresistance to a variety of kinase inhibitors, and found that in several examples, resistant cells are distinctly characterized by an increase in the number and/or length of cilia with altered structural features. Changes in cilia length seem to be linked to the lack of recruitment of Kif7 and IFT81 to cilia tips, and result in enhanced hedgehog pathway activation. Notably, Kif7 knockdown is sufficient to confer drug resistance in drug sensitive cells. Conversely, targeting of cilia length or integrity through genetic and pharmacological approaches overcomes kinase inhibitor resistance. The identification of a broad mechanism of pathway-unbiased drug resistance, represents a major advancement in oncology, and helps define a specific and important role for cilia in human cancer.

Correlation between levels of ferritin and the iron-containing component of ribonucleotide reductase in hydroxyurea-sensitive, -resistant, and -revertant cell lines

1991 ◽  
Vol 69 (9) ◽  
pp. 635-642 ◽  
Author(s):  
Robert A. R. Hurta ◽  
Jim A. Wright
Keyword(s):  
Enzyme Activity ◽  
Dna Synthesis ◽  
Cell Lines ◽  
Ribonucleotide Reductase ◽  
Protein Concentration ◽  
Reductase Activity ◽  
M2 Protein ◽  
Wild Type ◽  
L Cells ◽  
Ribonucleotide Reductase Activity

The reduction of ribonucleotides to deoxyribonucleotides, a rate-limiting step in DNA synthesis, is catalyzed by ribonucleotide reductase. This enzyme is composed of two components, M1 and M2. Recent work has shown that inhibition of ribonucleotide reductase by the antitumor drug hydroxyurea leads to a destabilized iron centre in protein M2. We have examined the relationship between the levels of ferritin, the iron storage protein, and the iron-containing M2 component of ribonucleotide reductase. These studies were carried out with hydroxyurea-sensitive, -resistant, and -revertant cell lines. Hydroxyurea-resistant mouse L cells contained M2 gene amplification and elevated levels of enzyme activity, M2 message, and total cellular M2 protein concentration. Hydroxyurea-revertant cells exhibited a wild-type M2 gene copy number, and approximately wild-type levels of enzyme activity, M2 message, and M2 protein concentration. In addition, we observed that the hydroxyurea-resistant cells possessed elevated levels of L-chain ferritin message and total cellular H-chain ferritin protein when compared to wild-type cells. In contrast, the revertant cell population contained approximately wild-type levels of ferritin mRNA and protein. In keeping with these observations, obtained with mouse L cells, was the finding that hydroxyurea-resistant Chinese hamster ovary cells with increased ribonucleotide reductase activity exhibited elevated expression of both ferritin and M2 genes, which declined in drug-sensitive revertant hamster cell lines with decreased levels of ribonucleotide reductase activity. This is the first demonstration that reversion of hydroxyurea resistance and a decline in ribonucleotide reductase activity are accompanied by decreased ferritin expression, and supports the concept that ferritin is important in establishing resistance to hydroxyurea, and may play a role in DNA synthesis, through the regulation of functional iron-containing M2 protein levels required for ribonucleotide reduction.Key words: ribonucleotide reductase, ferritin, hydroxyurea, drug resistance.

ARFGAP3 an androgen target gene promotes prostate cancer cell proliferation and migration.

2020 ◽  
Author(s):  
Lungwani Muungo
Keyword(s):  
Cell Proliferation ◽  
Cancer Cell ◽  
Cell Biology ◽  
Adaptor Protein ◽  
Cancer Cell Proliferation ◽  
Lncap Cells ◽  
Gtpase Activating Protein ◽  
Cell Proliferation And Migration ◽  
And Migration ◽  
Proliferation And Migration

ADP ribosylation factor GTPase-activating protein 3 (ARFGAP3) is a GTPase-activating protein that associates with the Golgiapparatus and regulates the vesicular trafficking pathway. In the present study, we examined the contribution of ARFGAP3 toprostate cancer cell biology. We showed that ARFGAP3 expression was induced by 100 nM of dihydrotestosterone (DHT) atboth the mRNA and protein levels in androgen-sensitive LNCaP cells. We generated stable transfectants of LNCaP cells withFLAG-tagged ARFGAP3 or a control empty vector and showed that ARFGAP3 overexpression promoted cell proliferation andmigration compared with control cells. We found that ARFGAP3 interacted with paxillin, a focal adhesion adaptor protein thatis important for cell mobility and migration. Small interfering RNA (siRNA)-mediated knockdown of ARFGAP3 showed thatARFGAP3 siRNA markedly reduced LNCaP cell growth. Androgen receptor (AR)-dependent transactivation activity on prostatespecificantigen (PSA) enhancer was synergistically promoted by exogenous ARFGAP3 and paxillin expression, as shown byluciferase assay in LNCaP cells. Thus, our results suggest that ARFGAP3 is a novel androgen-regulated gene that can promoteprostate cancer cell proliferation and migration in collaboration with paxillin.

Genotoxicity and Cell Proliferative Activity of 3-Chloro-4-(Dichloromethyl)-5-Hydroxy-2(5H)-Furanone [MX] in Rat Glandular Stomach

1992 ◽  
Vol 25 (11) ◽  
pp. 341-345 ◽  
Author(s):  
C. Furihata ◽  
M. Yamashita ◽  
N. Kinae ◽  
T. Matsushima
Keyword(s):  
Cell Proliferation ◽  
Body Weight ◽  
Dna Synthesis ◽  
Ornithine Decarboxylase ◽  
Tap Water ◽  
Fold Increase ◽  
Single Strand ◽  
Glandular Stomach ◽  
Decarboxylase Activity ◽  
Pyloric Mucosa

MX is a strong direct acting mutagen on Salmonella typhimurium TA100 and is present in chlorinated tap water which contains organic compounds. MX was administered orally to 7-week-old male F344 rats, and its geno-toxicity in the pyloric mucosa of stomach was examined by analysis of DNA single strand scissions by the alkaline elution method. The effect of MX on cell proliferation was examined by assays of the inductions of replicative DNA synthesis and ornithine decarboxylase. MX at closes of 20-48 mg/kg body weight induced DNA single strand scissions dose-dependently (p<0.02) in the pyloric mucosa of the stomach 2 h after its administration. Moreover at doses of 10-60 mg/kg body weight, it induced up to 21-fold increase in replicative DNA synthesis (p<0.01) 16 h after its administration. At doses of 10-60 mg/kg body weight, it induced up to 100-fold increase in ornithine decarboxylase activity with a maximum 16 h after its administration. These results suggest that MX is genotoxic and induces cell proliferation in the glandular stomach of rats.

Oncogenic LncRNA CASC9 in Cancer Progression

2020 ◽  
Vol 26 ◽  
Author(s):  
Yuying Qi ◽  
Chaoying Song ◽  
Jiali Zhang ◽  
Chong Guo ◽  
Chengfu Yuan
Keyword(s):  
Cell Proliferation ◽  
Drug Resistance ◽  
Cell Growth ◽  
Cancer Cells ◽  
Therapeutic Potential ◽  
Squamous Metaplasia ◽  
Neoplastic Transformation ◽  
Over Expression ◽  
Human Cancers ◽  
Current Review

Background: Long non-coding RNA (LncRNAs), with the length over 200 nucleotides, originate from intergenic, antisense, or promoter-proximal regions, is a large family of RNAs that lack coding capacity. Emerging evidences illustrated that LncRNAs played significant roles in a variety of cellular functions and biological processes in profuse human diseases, especially in cancers. Cancer susceptibility candidate 9 (CASC9), as a member of the LncRNAs group, was firstly found its oncogenic function in esophageal cancer. In following recent studies, a growing amount of human malignancies are verified to be correlated with CASC9, most of which are derived from the squamous epithelium tissue. This present review attempts to highlight the latest insights into the expression, functional roles, and molecular mechanisms of CASC9 in different human malignancies. Methods: In this review, the latest findings related to the pathophysiological processes of CASC9 in human cancers were summarized and analyzed, the associated studies were collected in systematically retrieval of PubMed used lncRNA and CASA9 as keywords. Results: CASC9 expression is identified to be aberrantly elevated in a variety of malignancies. The over-expression of CASC9 has been suggested to accelerate cell proliferation, migration, cell growth and drug resistance of cancer cells, while depress cell apoptosis, revealing its role as an oncogene. Moreover, the current review demonstrated CASC9 closely relates to neoplastic transformation of squamous epithelial cells and squamous metaplasia in non-squamous epithelial tissues. Finally, we discuss the limitations and tremendous diagnostic/therapeutic potential of CASC9 in various human cancers. Results: CASC9 expression is identified to be aberrantly elevated in a variety of malignancies. The over-expression of CASC9 has been suggested to accelerate cell proliferation, migration, cell growth and drug resistance of cancer cells, while depress cell apoptosis, revealing its role as an oncogene. Moreover, the current review demonstrated CASC9 closely relates to neoplastic transformation of squamous epithelial cells and squamous metaplasia in non-squamous epithelial tissues. Finally, we discuss the limitations and tremendous diagnostic/therapeutic potential of CASC9 in various human cancers. Conclusion: Long non-coding RNACASC9 likely served as useful disease biomarkers or therapy targets that could effectively apply in treatment of different kinds of cancers.

Clinical applications of circulating tumor DNA in monitoring breast cancer drug resistance

2020 ◽  
Vol 16 (34) ◽  
pp. 2863-2878
Author(s):  
Yang Liu ◽  
Qian Du ◽  
Dan Sun ◽  
Ruiying Han ◽  
Mengmeng Teng ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Drug Resistance ◽  
Digital Pcr ◽  
Circulating Tumor Dna ◽  
Resistance Mechanisms ◽  
Clinical Applications ◽  
Current Status ◽  
Cancer Drug ◽  
Genomic Alteration ◽  
Tumor Dna

Breast cancer is one of the leading causes of cancer-related deaths in women worldwide. Unfortunately, treatments often fail because of the development of drug resistance, the underlying mechanisms of which remain unclear. Circulating tumor DNA (ctDNA) is free DNA released into the blood by necrosis, apoptosis or direct secretion by tumor cells. In contrast to repeated, highly invasive tumor biopsies, ctDNA reflects all molecular alterations of tumors dynamically and captures both spatial and temporal tumor heterogeneity. Highly sensitive technologies, including personalized digital PCR and deep sequencing, make it possible to monitor response to therapies, predict drug resistance and tailor treatment regimens by identifying the genomic alteration profile of ctDNA, thereby achieving precision medicine. This review focuses on the current status of ctDNA biology, the technologies used to detect ctDNA and the potential clinical applications of identifying drug resistance mechanisms by detecting tumor-specific genomic alterations in breast cancer.

Dissecting the landscape of CAF-mediated drug resistance mechanisms in ALK-rearranged NSCLC

2020 ◽  
Vol 138 ◽  
pp. S48
Author(s):  
Q. Hu ◽  
L.L. Remsing Rix ◽  
X. Li ◽  
E.A. Welsh ◽  
B. Fang ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Resistance Mechanisms
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