101
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To KKW, Robey RW, Knutsen T, Zhan Z, Ried T, Bates SE. Escape from hsa-miR-519c enables drug-resistant cells to maintain high expression of ABCG2. Mol Cancer Ther 2010; 8:2959-68. [PMID: 19825807 DOI: 10.1158/1535-7163.mct-09-0292] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Overexpression of ABCG2 has been reported in cell lines selected for drug resistance and it is widely believed to be important in the clinical pharmacology of anticancer drugs. We and others have previously identified and validated two microRNAs (miRNA; hsa-miR-519c and hsa-miR-520h) targeting ABCG2. In this study, the shortening of the ABCG2 3' untranslated region (3'UTR) was found to be a common phenomenon in several ABCG2-overexpressing resistant cell lines, which as a result removes the hsa-miR-519c binding site and its repressive effects on mRNA stability and translation blockade, thereby contributing to drug resistance. On the other hand, reduced expression of hsa-miR-520h, previously thought to have allowed ABCG2 overexpression, was found to be caused by the sequestering of the miRNA by the highly expressed ABCG2. In drug-sensitive cells, inhibitors against hsa-miR-519c and hsa-miR-520h could augment the cytotoxic effect of mitoxantrone, suggesting a substantial role for both miRNAs in controlling ABCG2 level and thereby anticancer drug response. However, in drug-resistant cells, altering the levels of the two miRNAs did not have any effect on sensitivity to mitoxantrone. Taken together, these studies suggest that in ABCG2-overexpressing drug-resistant cells, hsa-miR-519c is unable to affect ABCG2 expression because the mRNA lacks its binding site, whereas hsa-miR-520h is sequestered and unable to limit ABCG2 expression. Given the recent observation that a truncated 3'UTR is also observed in ABCG2-overexpressing human embryonic stem cells, our results in drug-resistant cell lines suggest that 3'UTR truncation is a relatively common mechanism of ABCG2 regulation.
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MESH Headings
- 3' Untranslated Regions/genetics
- ATP Binding Cassette Transporter, Subfamily G, Member 2
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Cell Line, Tumor
- Chromosomes, Human/genetics
- Drug Resistance, Neoplasm/drug effects
- Drug Screening Assays, Antitumor
- Gene Expression Regulation, Neoplastic/drug effects
- Gene Rearrangement/drug effects
- Gene Silencing/drug effects
- Humans
- MicroRNAs/genetics
- MicroRNAs/metabolism
- Mitoxantrone/pharmacology
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- RNA Stability/drug effects
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Analysis, DNA
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Affiliation(s)
- Kenneth K W To
- School of Pharmacy, The Chinese University of Hong Kong, Hong Kong, Hong Kong.
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102
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Direct and transgenerational impact on Daphnia magna of chemicals with a known effect on DNA methylation. Comp Biochem Physiol C Toxicol Pharmacol 2009; 151:278-85. [PMID: 19961956 DOI: 10.1016/j.cbpc.2009.11.007] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 11/18/2009] [Accepted: 11/19/2009] [Indexed: 12/14/2022]
Abstract
The purpose of this study is to investigate (1) the induction of epigenetic effects in the crustacean Daphnia magna using DNA methylation as an epigenetic mark and (2) the potential stable transfer of such an epigenetic effect to non-exposed subsequent generations. Daphnids were exposed to chemical substances known to affect DNA methylation in mammals: vinclozolin, 5-azacytidine, 2'-deoxy-5-azacytidine, genistein and biochanin A. Effects on overall DNA cytosine methylation, body length and reproduction were evaluated in 21day experiments. Using a multi-generational experimental design these endpoints were also evaluated in the F(1) and F(2) generation of both exposed and non-exposed offspring from F(0) daphnids exposed to 5-azacytidine, genistein or vinclozolin. A reduction in DNA methylation was consistently observed in daphnids exposed to vinclozolin and 5-azacytidine. Only in organisms exposed to 5-azacytidine was this effect transferred to the two subsequent non-exposed generations. A concurrent reduction in body length at day 7 was observed in these treatments. For the first time, exposure to environmental chemicals was shown to affect DNA methylation in the parental generation of D. magna. We also demonstrated a transgenerational alteration in an epigenetic system in D. magna, which indicates the possibility of transgenerational inheritance of environment-induced epigenetic changes in non-exposed subsequent generations.
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103
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Prince HM, Bishton MJ, Harrison SJ. Clinical studies of histone deacetylase inhibitors. Clin Cancer Res 2009; 15:3958-69. [PMID: 19509172 DOI: 10.1158/1078-0432.ccr-08-2785] [Citation(s) in RCA: 273] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Over the last 5 years, a plethora of histone deacetylase inhibitors (HDACi) have been evaluated in clinical trials. These drugs have in common the ability to hyperacetylate both histone and nonhistone targets, resulting in a variety of effects on cancer cells, their microenvironment, and immune responses. To date, responses with single agent HDACi have been predominantly observed in advanced hematologic malignancies including T-cell lymphoma, Hodgkin lymphoma, and myeloid malignancies. Therefore, in this review we focus upon hematologic malignancies. Generally HDACi are well tolerated with the most common acute toxicities being fatigue, gastrointestinal, and transient cytopenias. Of note, few patients have been treated for prolonged periods of time and little is known about long-term toxicities. The use of the biomarker of histone hyperacetylation has been useful as a guide to target specificity, but generally does not predict for response and the search for more clinically relevant biomarkers must continue.
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Affiliation(s)
- H Miles Prince
- Division of Haematology and Medical Oncology, Peter MacCallum Cancer Centre, East Melbourne, Melbourne, Australia and University of Melbourne, Parkville, Victoria, Australia.
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104
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Stathis A, Hotte SJ, Chen EX, Hirte HW, Oza AM, Moretto P, Webster S, Laughlin A, Stayner LA, McGill S, Wang L, Zhang WJ, Espinoza-Delgado I, Holleran JL, Egorin MJ, Siu LL. Phase I study of decitabine in combination with vorinostat in patients with advanced solid tumors and non-Hodgkin's lymphomas. Clin Cancer Res 2009; 27:3528. [PMID: 21152384 PMCID: PMC2997755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
PURPOSE: This phase I study evaluated the safety, tolerability, pharmacokinetics and preliminary efficacy of the combination of decitabine with vorinostat. PATIENTS AND METHODS: Patients with advanced solid tumors or non-Hodgkin's lymphomas were eligible. Sequential and concurrent schedules were studied. RESULTS: Forty-three patients were studied in 9 different dose levels (6 sequential and 3 concurrent). The maximum tolerated dose (MTD) on the sequential schedule was decitabine 10 mg/m(2)/day on days 1-5 and vorinostat 200 mg three times a day on days 6-12. The MTD on the concurrent schedule was decitabine 10 mg/m(2)/day on days 1-5 with vorinostat 200 mg twice a day on days 3-9. However, the sequential schedule of decitabine 10 mg/m(2)/day on days 1-5 and vorinostat 200 mg twice a day on days 6-12 was more deliverable than both MTDs with fewer delays on repeated dosing and it represents the recommended phase II (RP2D) dose of this combination. Dose-limiting toxicities during the first cycle consisted of myelosuppression, constitutional and gastrointestinal symptoms and occurred in 12/42 (29%) patients evaluable for toxicity. The most common ≥ grade 3 adverse events were neutropenia (49% of patients), thrombocytopenia (16%), fatigue (16%), lymphopenia (14%), and febrile neutropenia (7%). Disease stabilization for ≥ 4 cycles was observed in 11/38 (29%) evaluable patients. CONCLUSION: The combination of decitabine with vorinostat is tolerable on both concurrent schedules in previously treated patients with advanced solid tumors or non-Hodgkin's lymphomas. The sequential schedule was easier to deliver. The combination showed activity with prolonged disease stabilization in different tumor types.
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Affiliation(s)
| | | | - Eric X. Chen
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Holger W. Hirte
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Amit M. Oza
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Patricia Moretto
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Sheila Webster
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Anne Laughlin
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Lee-Anne Stayner
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Shauna McGill
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Lisa Wang
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Wen-jiang Zhang
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
| | - Igor Espinoza-Delgado
- Investigational Drug Branch, Cancer Therapy Evaluation Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, Bethesda, MD
| | - Julianne L. Holleran
- Departments of Medicine and Pharmacology and Cancer Institute, University of Pittsburgh, Pittsburgh, PA
| | - Merrill J. Egorin
- Departments of Medicine and Pharmacology and Cancer Institute, University of Pittsburgh, Pittsburgh, PA
| | - Lillian L. Siu
- Princess Margaret Hospital Phase I Consortium, Toronto, ON, Canada
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