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Your search keyword '"Zhan, Zhirong"' showing total 37 results
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37 results on '"Zhan, Zhirong"'

16. Abstract 3399: Resistance to the histone deacetylase inhibitor romidepsin is associated with degradation of Bim following MAPK pathway activation.

Author

Chakraborty, Arup R., primary, Robey, Rob, additional, Zhan, Zhirong, additional, Luchenko, Victoria, additional, Gottesman, Michael, additional, Collie, Nathan, additional, Gillet, Jean-Pierre, additional, Piekarz, Richard, additional, Kossenkov, Andrew, additional, Showe, Louise, additional, and Bates, Susan, additional

Published
2013
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21. Use of peptide antibodies to probe for the mitoxantrone resistance-associated protein MXR/BCRP/ABCP/ABCG2

Author

Litman, Thomas, Jensen, Ulla, Hansen, Alastair, Covitz, Kuang-Ming, Zhan, Zhirong, Fetsch, Patricia, Abati, Andrea, Hansen, Paul Robert, Horn, Thomas, Skovsgaard, Torben, Bates, Susan E, Litman, Thomas, Jensen, Ulla, Hansen, Alastair, Covitz, Kuang-Ming, Zhan, Zhirong, Fetsch, Patricia, Abati, Andrea, Hansen, Paul Robert, Horn, Thomas, Skovsgaard, Torben, and Bates, Susan E

Abstract

Recent studies have characterized the ABC half-transporter associated with mitoxantrone resistance in human cancer cell lines. Encoded by the ABCG2 gene, overexpression confers resistance to camptothecins, as well as to mitoxantrone. We developed four polyclonal antibodies against peptides corresponding to four different epitopes on the mitoxantrone resistance-associated protein, ABCG2. Three epitopes localized on the cytoplasmic region of ABCG2 gave rise to high-affinity antibodies, which were demonstrated to be specific for ABCG2. Western blot analysis of cells with high levels of ABCG2 showed a single major band of the expected 72-kDa molecular size of ABCG2 under denaturing conditions. Immunoblot analysis performed under non-reducing conditions and after treatment with cross-linking reagents demonstrated a molecular weight shift from 72 kDa to several bands of 180 kDa and higher molecular weight, suggesting detection of dimerization products of ABCG2. Evidence of N-linked glycosylation was also obtained using tunicamycin and N-glycosidase F. Finally, both by light, fluorescence and electron microscopic immunohistochemical staining, we demonstrate cytoplasmic and predominantly plasma membrane localization of ABCG2 in cell lines with high levels of expression. Plasma membrane staining was observed on the surface of the chorionic villi in placenta. These results support the hypothesis that ABCG2 is an ABC half-transporter that forms dimers in the plasma membrane, functioning as an ATP-dependent outward pump for substrate transport.

Published
2002

33. Clinical Reversal of Multidrug Resistance

Author

Bates, Susan E., primary, Wilson, Wyndham H., additional, Fojo, Antonio T., additional, Alvarez, Manuel, additional, Zhan, Zhirong, additional, Regis, Joanna, additional, Robey, Rob, additional, Hose, Curtis, additional, Monks, Anne, additional, Kang, Yoon Koo, additional, and Chabner, Bruce, additional

Published
1996
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34. Measuring MDR-1 by Quantitative RT-PCR.

Author

Walker, John M., Brown, Robert, Böger-Brown, Uta, Bates, Susan E., Zhan, Zhirong, Regis, Joanna, and Gamelin, Erick

Abstract

Accurate determination of the expression of P-glycoprotein and its encoding mRNA, MDR-1, is key to determining the importance of this mechanism of drug resistance in the clinic. This understanding is critical to development of P-glycoprotein antagonists to block drug efflux and to overcome drug resistance. Reversal studies are best performed in diseases in which this mechanism represents the major component of drug resistance. The clearest approach to identifying these is to measure MDR-1 mRNA or P-glycoprotein in tumors at diagnosis, at the time of disease recurrence, and before and after treatment with P-glycoprotein reversal agents. [ABSTRACT FROM AUTHOR]

Published
1999
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35. Expression of mdr-1 in Refractory Lymphoma: Quantitation by Polymerase Chain Reaction and Validation of the Assay

Author

Kang, Yoon-Koo, Zhan, Zhirong, Regis, Joanna, Robey, Robert, Meadows, Beverly, Dickstein, Bruce, Lee, Jong Seok, Otsuki, Takemi, Stetler-Stevenson, Maryalice, Jaffe, Elaine S., Solomon, Diane, Wilson, Wyndham H., Fojo, Antonio, and Bates, Susan E.

Abstract

Measurement of P-glycoprotein and the gene that encodes it, mdr-1, is an important tool for assessing the impact of multidrug resistance in clinical cancer. We evaluated mdr-1 expression by a quantitative polymerase chain reaction (PCR) assay in 78 biopsy samples from 48 patients with refractory lymphoma enrolled on a trial of infusional chemotherapy (EPOCH) in which R-verapamil was added as an antagonist of P-glycoprotein in a subset of patients whose tumors were unresponsive to treatment. Expression of mdr-1 was detectable in all biopsies at the time of enrollment on study, and a fourfold or greater increase in mdr-1 expression was noted in 42% of patients at the time of treatment failure. Expression of mdr-1 was also detectable in biopsies from patients at the time of diagnosis of lymphoma. An endogenous control gene, β2-microglobulin, was quantrtated for normalization of the mdr-1 values. The use of β2-microglobulin expression for normalization was validated in a subset of samples by comparing Northern blots detecting β2-micro-globulin, β-actin, and GAPDH gene expression. Immunoblot analysis suggested that no major discrepancy was present between mRNA expression and protein level. Immunophe-notyping of lymphomatous lymph nodes showed that infiltration of tumor cells ranged from 8% to 95% and of normal T cells from 1% to 83%. Expression of mdr-1 in normal T cells and monocytes was also shown to be low. The mdr-1 levels in patient samples were independent of T-cell contamination, suggesting that the presence of normal cells has at best a small impact on mdr-1 measurements. Expression of mdr-1 in lymphoma can be quantrtated by PCR, and wide variations in expression can be observed. Increased expression in patients with refractory disease supports an important role for Pgp in drug resistance in lymphoma. These studies will aid in the design and interpretation of clinical trials in lymphoma.

Published
1995
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36. [Nasal mucosa remodeling in chronic rhinosinusitis without nasal polyps].

Author

Li X, Zhan Z, Sun J, Zeng B, Xue Y, and Wang S

Subjects
Adolescent, Adult, Aged, Case-Control Studies, Chronic Disease, Female, Humans, Male, Middle Aged, Nasal Polyps complications, Sinusitis complications, Young Adult, Nasal Mucosa pathology, Sinusitis pathology
Abstract

Objective: To explore the feature of nasal mucosa remodeling in chronic rhinosinusitis without nasal polyps (CRSsNP)., Method: Histological specimens from 30 selected patients with CRSsNP who underwent endoscopic sinus surgery and 10 control subjects were studied. The paraffin sections were stained with hematoxylin-eosin(HE), alcian blue-periodic acid-Schiff (AB-PAS), Masson trichrome (MT) and Picric acid-Sirius red. The damage of epithelium, goblet cells and gland hyperplasia, deposition of collagen in extracellular matrix, the thickness of basement membrane and the type of collagen were observed respectively., Result: Grade 0, Grade 1, Grade 2 and Grade 3 of epithelial damage were significantly different in the CRSsNP group when compared with the control group (P < 0.01 or P < 0.05). Evident mucus gland hyperplasia and collagen deposition in extracellular matrix were observed in CRSsNP group (P < 0.01). The number of goblet cells and the thickness of basement membrane were increased obviously in CRSsNP group (P < 0.01). The collagen deposited in extracellular matrix was mainly composed of collagen type I. Collagen type III and collagen type IV was much less than collagen type I., Conclusion: The nasal mucosa remodeling was observed in CRSsNP group and was characterized by epithelial damage, basement membrane thickening, deposition of collagen in extracellular matrix, goblet cells and mucus gland hyperplasia.

Published
2013

37. The challenge of exploiting ABCG2 in the clinic.

Author

Robey RW, Ierano C, Zhan Z, and Bates SE

Subjects
ATP Binding Cassette Transporter, Subfamily G, Member 2, ATP-Binding Cassette Transporters antagonists & inhibitors, ATP-Binding Cassette Transporters genetics, Animals, Cell Line, Tumor, Clinical Trials as Topic, Humans, Neoplasm Proteins antagonists & inhibitors, Neoplasm Proteins genetics, Neoplasms drug therapy, Neoplasms genetics, Organ Specificity, Polymorphism, Single Nucleotide, Substrate Specificity, ATP-Binding Cassette Transporters physiology, Drug Resistance, Multiple drug effects, Neoplasm Proteins physiology, Neoplasms metabolism
Abstract

ABCG2, or breast cancer resistance protein (BCRP), is an ATP-binding cassette half transporter that has been shown to transport a wide range of substrates including chemotherapeutics, antivirals, antibiotics and flavonoids. Given its wide range of substrates, much work has been dedicated to developing ABCG2 as a clinical target. But where can we intervene clinically and how can we avoid the mistakes made in past clinical trials targeting P-glycoprotein? This review will summarize the normal tissue distribution, cancer tissue expression, substrates and inhibitors of ABCG2, and highlight the challenges presented in exploiting ABCG2 in the clinic. We discuss the possibility of inhibiting ABCG2, so as to increase oral bioavailability or increase drug penetration into sanctuary sites, especially the central nervous system; and at the other end of the spectrum, the possibility of improving ABCG2 function, in the case of gout caused by a single nucleotide polymphism. Together, these aspects of ABCG2/BCRP make the protein a target of continuing interest for oncologists, biologists, and pharmacologists.

Published
2011
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