• Journal of Life Science
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• v.15 no.6 s.73
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• pp.994-1004
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• 2005

The dihydrofolate reductase (dhfr) promoter contains cis-acting element for the transcription factors Spl and E2F. Transcription of dhfr gene shows maximal activity during the Gl/S phase of cell cycle. The member of the Spl transcriptional factor family can act as both negative and positive regulators of gene expression. There was a report that Spl-Rb and E2F4-pl30 complexes cooperate to establish stable repression of dhfr gene expression in CHOC400 cells. Here, we examined the role of HDAC in dhfr, cyclin E, and cyclin A gene regulation using the histone deacetylation inhibitor, trichostatin A (TSA) in U2OS and C33A cells, a Rb-positive human osteosarcoma cell line, and a Rb-negative cervical carcinoma cell line, respectively. When the dhfr promoter constructs were applied in U2OS cells, TSA markedly stimulated over 14-fold of dhfr promoter activity through dhfr-Spl sites by the deletion of an E2F element. In contrast, the deletion of dhfr-Spl binding sites completely abolished promoter stimulation by TSA. The dhfr promoter activity including dhfr-Spl sites increased only 2-fold in C33A cells. Promoter activity containing only dhfr-E2F site did not have much effect by the treatment of TSA in both U2OS and C33A cells. On the other hand, treatment with TSA induced significantly mRNA expression of dhfr and cyclin E, whereas levels of cyclin A decreased in U2OS cells, but had no effect in C33A cells. These results indicate that TSA have contradictory effect, activation of dhfr and cyclin E genes on Gl phase, and down-regulation of cyclin A on G2 phase through transcriptional regulation in U2OS cells.

• Journal of Life Science
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• v.19 no.9
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• pp.1314-1320
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• 2009

Histone deacetylase inhibitor (HDACI) is a new promising candidate as an antineoplastic agent for the treatment of solid and hematologic malignancies. In order to evaluate cell death and to elucidate the related mechanism(s) in NSCLC cells after HDACI, sodium butyrate (SB), a representative HDACI, was used to treat H460 cells for 48 hrs. SB exposure resulted in a significant reduction of cell viability at concentrations below 7.5 mM, and about 50% of cell death occurred at 20 mM. The types of cell death induced by SB were both apoptosis and necrosis, evaluated by Annexin-V staining combined with propidium iodide. SB treatment significantly evoked G2/M cell cycle arrest and subsequently induced cell death with caspase-dependent manner. While ERK protein content was not altered after SB, phosphorylated forms of ERK were markedly reduced. Taken together, SB is significantly able to induce cell death in NSCLC cell line H460, and it is suggested that the reduction of ERK phosphorylation might be closely involved in the cancer cell death mechanism initiated by HDACI.