Role of P27(Kip1) and TGF-beta1 in APL cell apoptosis induced by As(2)O(3) / 中国实验血液学杂志

The aim of study was to investigate the effects of arsenic trioxide (As(2)O(3)) on cell cycle and apoptosis of APL cells, as well as changes of P27(Kip1), endogenous TGF-beta1, cyclin E and bcl-2, and to explore the relationship between expression of P27(Kip1) and apoptosis induced by As(2)O(3). The apoptosis and cell cycle changes of APL cells treated with As(2)O(3) were detected by morphology and flow cytometry respectively, the protein and mRNA expressions of P27(Kip1), TGF-beta1, cyclin E and BCL-2 were measured by immunohistochemistry and RT-PCR. The results indicated that As(2)O(3) induced APL cell apoptosis in vitro, and cell cycle was arrested at G(1) phase. Apoptotic cells induced by As(2)O(3) 1, 5 and 10 micromol/L for 24 hours were 1.42%, 4.57% and 10.67% respectively; the proportion of apoptotic cells induced by As(2)O(3) of same concentrations for 48 hours increased to 8.92%, 16.07% and 18.90% respectively; the cells induced by As(2)O(3) for 72 hours were mainly in debris. Protein and mRNA expressions of P27(Kip1) and TGF-beta1 of APL cells after treatment with As(2)O(3) increased, accompanying with decrease of cyclin E, bcl-2 protein and mRNA expressions. Apoptotic cells were related to the expressions of P27(Kip1) (r(mRNA) = 0.55, p < 0.05) and TGF-beta1 (r(mRNA) = 0.51, p < 0.05). There was positive correlation between the expression of TGF-beta1 and of P27(Kip1) (r(mRNA) = 0.31, p < 0.05). It is concluded that the apoptosis of APL cells is induced by As(2)O(3), and the cell cycle is arrested at G(1) phase. The expression of P27(Kip1) is closely related to the extent of apoptosis induced by As(2)O(3). Apoptosis of APL cells induced by As(2)O(3) may be caused by up-regulating TGF-beta1 and P27(Kip1), which is antagonistic to cyclin E and BLC-2, leading to arrest of cell cycle at G(1) phase.

Studies on gene expression and the 5' CpG islands methylation status of E-cadherin in acute myeloid leukemia / 中华血液学杂志

<p><b>OBJECTIVE</b>To study the relationship between E-cadherin gene expression and the methylation status of E-cadherin 5' CpG islands in acute myeloid leukemia (AML).</p><p><b>METHODS</b>Reverse transcription-PCR (RT-PCR), flow cytometry and methylation specific PCR were used to analyze the E-cadherin gene and protein expression and its 5' CpG island methylation status respectively in bone marrow cells from 55 AML patients and 7 normal controls.</p><p><b>RESULTS</b>AML cells displayed a significant reduction or lack of E-cadherin gene and protein expression, the positive rates were 23.6% and 18.2% (P < 0.01), respectively. All normal bone marrow cells were E-cadherin positive. Thirty-eight of the 55 patients (69.1%) were E-cadherin 5' CpG island methylated whereas the normal controls were completely unmethylated. Twenty-nine of thirty-one (93.5%) E-cadherin-negative samples showed abnormal hypermethylation of the E-cadherin CpG islands.</p><p><b>CONCLUSION</b>Expression downregulation and methylation of E-cadherin gene in AML suggest that it might be an important event in AML. E-cadherin methylation was associated with the inhibition of E-cadherin gene and protein expression in AML.</p>

Analysis of methylation status of the promoter of mdr1 gene in K562 and K562/DNR cells / 中华血液学杂志

<p><b>OBJECTIVE</b>To analyze the methylation patterns of mdr1 gene promotor in both K562 cell and K562/DNR cells and the relationship between promotor methylation and P-gp expression.</p><p><b>METHODS</b>mdr1 gene expression was analyzed by flow cytometry and RT-PCR, methylation status of the promotor of mdr1 gene by bisulfite-sequencing (including two GC-box).</p><p><b>RESULTS</b>mdr1 gene was found methylated at GC-box and not expressed in K562 cells, but unmethylated and expressed respectively in K562/DNR cells.</p><p><b>CONCLUSION</b>The methylation patterns of mdr1 gene promotor in K562/DNR and K562 cells were different. mdr1 gene silencing was associated with the promotor methylation.</p>