Down-regulation of human topoisomerase IIα correlates with altered expression of transcriptional regulators NF-YA and Sp1

Allen, Kirsty Ann; Williams, Amram O; Isaacs, Richard; Stowell, Kathryn M.

doi:10.1097/00001813-200404000-00008

Cited by 10 publications

(6 citation statements)

References 24 publications

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“…We have previously shown that Sp1 can up-regulate transcription of topoisomerase IIα [9,18] and this current study supports Sp1 as a transcriptional activator of topoisomerase IIα. These findings are consistent with other work, which has shown that in the rat topoisomerase IIα promoter, Sp1 is a transcriptional activator at the GC2 element, which is spatially equivalent to the GC1 element of the human topoisomerase IIα promoter [23].…”

Section: Discussionsupporting

confidence: 86%

“…The effects of Sp1 and Sp3 on transcription were tested by co-transfecting increasing amounts of Sp1 and Sp3 expression vectors respectively (Figure 3). Sp1 has been shown previously to be a transcriptional activator in both HeLa [9] and MDA MB 231 [18]. Figure 3 clearly shows Sp3 acts as a transcriptional repressor of human topoisomerase IIα by decreasing expression in a dose-dependent manner by approximately 60% at the highest concentration used.…”

Section: Resultsmentioning

confidence: 75%

“…The cells were exposed to a single dose of Adriamycin (5 μM) for 1 h [18]. Extractions were carried out at time 0 h (control, unexposed cells) and 2 and 24 hours after exposure.…”

Section: Methodsmentioning

confidence: 99%

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Down-regulation of human topoisomerase IIα expression correlates with relative amounts of specificity factors Sp1 and Sp3 bound at proximal and distal promoter regions

2007

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BackgroundTopoisomerase IIα has been shown to be down-regulated in doxorubicin-resistant cell lines. The specificity proteins Sp1 and Sp3 have been implicated in regulation of topoisomerase IIα transcription, although the mechanism by which they regulate expression is not fully understood. Sp1 has been shown to bind specifically to both proximal and distal GC elements of the human topoisomerase IIα promoter in vitro, while Sp3 binds only to the distal GC element unless additional flanking sequences are included. While Sp1 is thought to be an activator of human topoisomerase IIα, the functional significance of Sp3 binding is not known. Therefore, we sought to determine the functional relationship between Sp1 and Sp3 binding to the topoisomerase IIα promoter in vivo. We investigated endogenous levels of Sp1, Sp3 and topoisomerase IIα as well as binding of both Sp1 and Sp3 to the GC boxes of the topoisomerase IIα promoter in breast cancer cell lines in vivo after short term doxorubicin exposure.ResultsFunctional effects of Sp1 and Sp3 were studied using transient cotransfection assays using a topoisomerase IIα promoter reporter construct. The in vivo interactions of Sp1 and Sp3 with the GC elements of the topoisomerase IIα promoter were studied in doxorubicin-treated breast cancer cell lines using chromatin immunoprecipitation assays. Relative amounts of endogenous proteins were measured using immunoblotting. In vivo DNA looping mediated by proteins bound at the GC1 and GC2 elements was studied using the chromatin conformation capture assay. Both Sp1 and Sp3 bound to the GC1 and GC2 regions. Sp1 and Sp3 were transcriptional activators and repressors respectively, with Sp3 repression being dominant over Sp1-mediated activation. The GC1 and GC2 elements are linked in vivo to form a loop, thus bringing distal regulatory elements and their cognate transcription factors into close proximity with the transcription start site.ConclusionThese observations provide a mechanistic explanation for the modulation of topoisomerase IIα and concomitant down-regulation that can be mediated by topoisomerase II poisons. Competition between Sp1 and Sp3 for the same cognate DNA would result in activation or repression depending on absolute amounts of each transcription factor in cells treated with doxorubicin.

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Section: Discussionsupporting

confidence: 86%

Section: Resultsmentioning

confidence: 75%

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Down-regulation of human topoisomerase IIα expression correlates with relative amounts of specificity factors Sp1 and Sp3 bound at proximal and distal promoter regions

2007

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“…TOP2A is an essential nuclear enzyme with a role in the maintenance of DNA topology and reportedly a target for several anticancer drugs including doxorubicin (18 -22). Decreased expression of TOP2A has been observed in a variety of cell lines that were resistant to a range of chemotherapeutic drugs (18,19,22). TOP2A-targeting anticancer drugs stabilize the TOP2A-DNA cleavable complex, prevent annealing of DNA strands, and cause subsequent double-stranded DNA breakage that leads to cell death.…”

Section: Discussionmentioning

confidence: 99%

Predicting Response to Methotrexate, Vinblastine, Doxorubicin, and Cisplatin Neoadjuvant Chemotherapy for Bladder Cancers through Genome-Wide Gene Expression Profiling

Takata

Katagiri

Kanehira

et al. 2005

Clinical Cancer Research

215

120

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Purpose: Neoadjuvant chemotherapy for invasive bladder cancer, involving a regimen of methotrexate, vinblastine, doxorubicin, and cisplatin (M-VAC), can improve the resectability of larger neoplasms for some patients and offer a better prognosis. However, some suffer severe adverse drug reactions without any effect, and no method yet exists for predicting the response of an individual patient to chemotherapy. Our purpose in this study is to establish a method for predicting response to the M-VAC therapy. Experimental Design: We analyzed gene expression profiles of biopsy materials from 27 invasive bladder cancers using a cDNA microarray consisting of 27,648 genes, after populations of cancer cells had been purified by laser microbeam microdissection. Results: We identified dozens of genes that were expressed differently between nine “responder” and nine “nonresponder” tumors; from that list we selected the 14 “predictive” genes that showed the most significant differences and devised a numerical prediction scoring system that clearly separated the responder group from the nonresponder group. This system accurately predicted the drug responses of 8 of 9 test cases that were reserved from the original 27 cases. Because real-time reverse transcription–PCR data were highly concordant with the cDNA microarray data for those 14 genes, we developed a quantitative reverse transcription–PCR–based prediction system that could be feasible for routine clinical use. Conclusions: Our results suggest that the sensitivity of an invasive bladder cancer to the M-VAC neoadjuvant chemotherapy can be predicted by expression patterns in this set of genes, a step toward achievement of “personalized therapy” for treatment of this disease.

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“…These results suggested that BM-cyclin 1 could effectively reverse drug resistance in C-A120 cells. With respect to the Topo II poisons, the level or activity of the Topo IIa enzyme can determine the amount of druginduced DNA damage that occurs and in turn might determine the cytotoxicity of the treatment [2]. In addition to the classical MDR, which is due to the overexpression of the MDR transporter (e.g.…”

Section: Discussionmentioning

confidence: 99%

Reversal effect of BM-cyclin 1 on multidrug resistance in C-A120 cells

Wang¹,

Sun²,

Li³

et al. 2007

Anti-Cancer Drugs

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In this study, multidrug-resistant human epidermoid C-A120 cells and the sensitive parental KB cells were used as experimental models. BM-cyclin 1, a traditional antimycoplasma drug, was tested to explore the reversal effect of multidrug resistance and its mechanisms in these cell lines. The MTT analysis showed that BM-cyclin 1 could reverse multidrug resistance effectively in C-A120 cells; the sensitivity of C-A120 cells to adriamycin, etoposide and cisplatin was enhanced by 6.0, 8.2 and 1.7 times, respectively. Immunoblotting analysis and reverse transcription-polymerase chain reaction were used to study the BM-cyclin 1-induced changes in topoisomerase IIalpha. The results showed that the expression of topoisomerase IIalpha in treated C-A120 cells increased significantly. Topoisomerase II catalytic activity increased by 30% compared with the untreated cells, as measured by decatenation of kinetopolast DNA. Immunoblotting analysis also indicated the transcription factor levels of specificity: those of protein 1 (Sp1) and nuclear factor-YA increased after treatment with BM-cyclin 1, whereas the mRNA and protein expression of multidrug resistance protein 2 was significantly downregulated. These results demonstrated that BM-cyclin 1 could effectively reverse the multidrug resistance of C-A120 cells by increasing the expression of topoisomerase IIalpha and by suppressing the expression of multidrug resistance protein 2, strongly suggesting that BM-cyclin 1 is a potential multidrug resistance reversal agent.

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Down-regulation of human topoisomerase IIα correlates with altered expression of transcriptional regulators NF-YA and Sp1

Cited by 10 publications

References 24 publications

Down-regulation of human topoisomerase IIα expression correlates with relative amounts of specificity factors Sp1 and Sp3 bound at proximal and distal promoter regions

Down-regulation of human topoisomerase IIα expression correlates with relative amounts of specificity factors Sp1 and Sp3 bound at proximal and distal promoter regions

Predicting Response to Methotrexate, Vinblastine, Doxorubicin, and Cisplatin Neoadjuvant Chemotherapy for Bladder Cancers through Genome-Wide Gene Expression Profiling

Reversal effect of BM-cyclin 1 on multidrug resistance in C-A120 cells

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