Unstable Expression of the Multi-Drug-Resistant Phenotype in Chinese Hamster Ovary Cells Resistant to Okadaic Acid

Tohda, Hiroko; Takao, Masashi; Kikuchi, Akihiko; Yasumoto, Takeshi; Yasui, Akira

doi:10.1006/bbrc.1997.6293

Cited by 11 publications

(13 citation statements)

References 18 publications

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“…In the present study, the resistant GH 3 cells displayed mdr1b mRNA levels which increased in parallel with the level of OA resistance. These results are consistent with those reported for OA-resistant Chinese hamster ovary cells (Tohda et al 1997) and for OA-resistant NIH 3T3 fibroblasts (Wang et al 1995), suggesting that OA is a P-glycoprotein substrate. This hypothesis is supported by a report that P-glycoprotein expressing KB cells resistant to vinblastine displayed an OA cross-resistance which was sensitized by verapamil, a known mdr1 modifier (Chambers et al 1993).…”

Section: Discussionsupporting

confidence: 92%

“…as homogeneously staining regions (Cowell 1982). While resistant cells with intrachromosomal amplifications have been shown to maintain stable overexpression (Zhou et al 1996) and do not regain sensitivity when incubated without the drug used for selection, resistance mediated by extrachromosomal DNA is easily lost (Von Hoff et al 1991;Tohda et al 1997;Sanchez et al 1998). LoVoDx cells which contain extrachromosomal DNA exhibit unstable mdr1-mediated doxorubicin resistance.…”

Section: Discussionmentioning

confidence: 99%

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Contribution of mdr1b-type P-glycoprotein to okadaic acid resistance in rat pituitary GH 3 cells

Ritz

Marwitz

Sieder

et al. 1999

Naunyn-Schmiedeberg's Archives of Pharmacology

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Okadaic acid as well as other, structurally different, inhibitors of serine/threonine phosphatases 1 and 2A induce apoptosis in pituitary GH3 cells. Incubation with stepwise raised concentrations of okadaic acid resulted in the isolation of cells that were increasingly less sensitive to the cytotoxic effect of this agent. After about 18 months cells were selected that survived at 300 nM okadaic acid, which is about 30 times the initially lethal concentration. This study revealed that a major pharmacokinetic mechanism underlying cell survival was the development of a P-glycoprotein-mediated multidrug resistance (MDR) phenotype. The increase in mRNA levels of the mdr1b P-glycoprotein isoform correlated with the extent of drug resistance. Functional assays revealed that increasing drug resistance was paralleled by a decreased accumulation of rhodamine 123, a fluorescent dye which is a substrate of mdr1-mediated efflux activity. Resistance could be abolished by structurally different chemosensitizers of P-glycoprotein function like verapamil and reserpine but not by the leukotriene receptor antagonist MK571 which is a modulator of the multidrug resistance-associated protein (MRP). Okadaic acid resistance included cross-resistance to other cytotoxic agents that are substrates of mdr1-type P-glycoproteins, like doxorubicin and actinomycin D, but not to non-substrates of mdr1, e.g. cytosine arabinoside. Thus, functional as well as biochemical features support the conclusion that okadaic acid is a substrate of the mdr1-mediated efflux activity in rat pituitary GH3 cells. Maintenance of resistance after withdrawal of okadaic acid as well as metaphase spreads of 100 nM okadaic acid-resistant cells suggested a stable MDR genotype without indications for the occurrence of extrachromosomal amplifications, e.g. double minute chromosomes.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Contribution of mdr1b-type P-glycoprotein to okadaic acid resistance in rat pituitary GH 3 cells

Ritz

Marwitz

Sieder

et al. 1999

Naunyn-Schmiedeberg's Archives of Pharmacology

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“…As shown in Fig. 13, ERK1/2 in four cell lines derived from Chinese hamster tissues, including okadaic acid-resistant CHO cell lines OAR2-3 and OAR6-6 (Tohda et al, 1997), was significantly activated by suramin. Human cell lines OVK18 (human ovarian carcinoma) and transformed human endothelium cells ECV304 (Takahashi et al, 1990), both exert high endogenous ERK1/2 activity, showed no significant activation of ERK1/2 by suramin.…”

Section: Map Kinase Activation By Suramin 749mentioning

confidence: 85%

Stimulation of Extracellular Signal-Regulated Kinase Pathway by Suramin with Concomitant Activation of DNA Synthesis in Cultured Cells

Nakata¹

2003

J Pharmacol Exp Ther

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Suramin is a well known antitrypanosomal drug and a novel experimental agent for the treatment of several cancers, yet the molecular mechanisms through which suramin exerts its effects on cell functions are not completely clear. In this study, we investigated the potential of suramin to activate the mitogenactivated protein kinase cascade in cultured Chinese hamster ovary (CHO) cells. The treatment of CHO cells with suramin increased the enzyme activity of extracellular signal-regulated kinases (ERK1/2) approximately 10-fold dose and time dependently. The EC 50 value was approximately 2.4 M. This activation is inhibited by PD98059 and wortmannin/LY294002, indicating a crucial role for mitogen-activated protein kinase kinase (MEK) and phosphatidylinositol 3-kinase (PI3K), respectively. Suramin-mediated stimulation of PI3K was confirmed by the observation that suramin stimulates the phosphorylation of protein kinase B (Akt) in a wortmannin-sensitive manner. Furthermore, cAMP response element-binding protein, a transcription factor, was also activated by suramin in a MEK-dependent manner. The suramin-induced phosphorylation of cGMP-dependent protein kinase was also suggested by a solid-phase kinase assay. The suramin effects on CHO cells were shown to have a concomitant increase in DNA synthesis, which was attenuated by PD98059. Similar activation of ERK1/2 activity by suramin was observed in other cell lines such as Chinese hamster lung or PC12 cells, but not in RBL2H3, ECV304, and OVK18 cells, indicating a cell-type specific mechanism for suramin. These results indicate that suramin induces mitogenic activity in several cell lines through the pathway from PI3K to MEK and ERK.Suramin, a polysulfonated napthylurea, has been noted to have trypanocidal activity and thus became the drug of choice for African trypanosomas and onchocerchiasis (Hawking, 1978). Suramin is also known to show various biological activities (Voogd et al., 1993), including the inhibition of several signaling pathways such as growth factor receptors, P2 purinergic receptors (Dunn and Blakeley, 1988), and uncoupling G proteins from G protein-coupled receptors (Freissmuth et al., 1996). Recently, suramin was tested for its usefulness in the treatment of malignant neoplasia, including ovarian and prostate cancers, because of its strong antiangiogenesis activity. Suramin can effectively suppress the proliferation and migration of cells as well as the formation of new blood vessels by blocking the action of several growth factor-mediated processes essential for the development and progression of malignant tumors (Yayon and Klagsbrun, 1990;Pesenti et al

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“…One of the isolated clones, 4E12, recognized a NH 2 -terminal fragment (residues numbers 1-40), and was cross-reactive to rodent topo II␣ (26).…”

Section: Antibodiesmentioning

confidence: 99%

“…One of the isolated clones, 3B6, was also reactive to rodent topo II␤ (26), recognizing a COOH-terminal fragment (residues numbers 1178 -1273).…”

Section: Antibodiesmentioning

confidence: 99%

Involvement of DNA Topoisomerase IIβ in Neuronal Differentiation

Tsutsui

Sano

et al. 2001

Journal of Biological Chemistry

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105

123

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Two isoforms of DNA topoisomerase II (topo II) have been identified in mammalian cells. While topo II␣ is essential for chromosome segregation in mitotic cells, in vivo function of topo II␤ remains to be clarified. Here we demonstrate that the nucleoplasmic topo II␤, highly expressed in differentiating cerebellar neurons, is the catalytically competent entity operating directly on chromatin DNA in vivo. When the cells reached terminal differentiation, this in vivo activity decreased to a negligible level with concomitant loss of the nucleoplasmic enzyme. Effects of topo II-specific inhibitors were analyzed in a primary culture of cerebellar granule neurons that can mimic the in vivo situation. Only the ␤ isoform was expressed in granule cells differentiating in vitro. ICRF-193, a catalytic topo II inhibitor, suppressed the transcriptional induction of amphiphysin I which is essential for mature neuronal activity. The effect decreased significantly as the cells differentiate. Expression profiling with a cDNA macroarray showed that 18% of detectable transcripts were up-regulated during the differentiation and one-third of them were susceptible to ICRF-193. The results suggest that topo II␤ is involved in an early stage of granule cell differentiation by potentiating inducible neuronal genes to become transcribable probably through alterations in higher order chromatin structure. DNA topoisomerase II (topo II)1 is essential for cell proliferation since some mitotic events such as condensation and segregation of daughter chromosomes are entirely dependent on its activity. It is also likely to be involved in other DNA transactions like DNA replication, transcription, and recombination (1). The enzyme, in a heart-shaped dimer form (2), catalyzes topological transformations of DNA by transient cleavage of DNA double strands forming an enzyme-operated gate, followed by passing a second double-stranded DNA segment through the gate (3, 4). Only one form of topo II is present in lower eukaryotes and invertebrates whereas in mammalian cells two isoforms, the 170-kDa topo II␣ and the 180-kDa topo II␤, that are encoded by separate genes have been identified (5-7). These isoforms may share their roles in different cellular functions although they show similar catalytic properties in vitro. From the following observations, topo II␣ is considered to be the main isoform involved in the mitotic processes. First, there is a positive correlation between the cellular concentration of topo II␣ and the rate of cell proliferation (8, 9). Second, the expression of mRNA for topo II␣ is higher in tissues containing proliferating cells (10) and is localized in brain regions enriched with mitotic cells (11,12). Third, the level of topo II␣ protein peaks at G 2 /M phase during the cell cycle (9, 13) and finally, high affinity binding of topo II␣ with chromatin at mitosis is essential for chromosome condensation/segregation and topo II␤ cannot be substituted for topo II␣ (14).In contrast to topo II␣, functional aspect of topo II␤ remains obscu...

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Unstable Expression of the Multi-Drug-Resistant Phenotype in Chinese Hamster Ovary Cells Resistant to Okadaic Acid

Cited by 11 publications

References 18 publications

Contribution of mdr1b-type P-glycoprotein to okadaic acid resistance in rat pituitary GH 3 cells

Contribution of mdr1b-type P-glycoprotein to okadaic acid resistance in rat pituitary GH 3 cells

Stimulation of Extracellular Signal-Regulated Kinase Pathway by Suramin with Concomitant Activation of DNA Synthesis in Cultured Cells

Involvement of DNA Topoisomerase IIβ in Neuronal Differentiation

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