Effects of specific siRNA targeting at bcr-abl fusion gene and its combination with p27 gene clone on chronic myeloid leukemia cell line K562 / 中国实验血液学杂志

This study was purposed to explore the effect of specific small interfering RNA targeting at bcr-abl fusion gene and its combination with p27 gene clone on the proliferation, cell cycle and apoptosis of chronic myeloid leukemia (CML) cell line K562. CML cell line K562 was used as the study object. A 21nt siRNA targeting at the fusion site of b3:a2 mRNA in bcr-abl fusion gene was designed, synthesized and transfected into the K562 cells as RNA interference group. Northern blot was used to detect the bcr-abl fusion gene, Western blot was used to detect the expression of P210 protein and apoptosis-related protein BCL-xL after the transfection. Meanwhile, p27 gene was amplified from peripheral blood mononuclear cells by RT-PCR, and was confirmed to be correct by sequencing, then p27-pcDNA3.1 vector was constructed and transfected into K562 cell line by Lipofectin. After being selected with G418, p27-pcDNA3.1-K562 cell clone stably expressing p27 was isolated. P27 protein was identified by Western blot. Finally, siRNA and p27 gene clone were together applied to K562 cells, the cell survival rate was tested by MTT. The cell cycle and the apoptosis were tested by flow cytometry. The result showed that in contrast with the control group, the expression level of bcr-abl fusion gene was much lower in siRNA group, about 18.4% of K562 cells in siRNA group were apoptotic at 24 hours after siRNA transfection, and the expression of apoptosis-associated protein BCL-xL was greatly down-regulated. The expression of P27 protein could be detected by Western blot in p27-pcDNA3.1-K562 cells. The strong inhibition of cell proliferation was observed in p27-pcDNA3.1-K562 cells, as compared with control K562 cells. The count of p27-pcDNA3.1-K562 cells in G(0)/G(1) phase increased apparently, but that in S phase declined greatly. Cell cycle was arrested in G(0)/G(1) phase. After the combination of p27-pcDNA3.1-K562 cells with specific siRNA, the percentage of apoptosis obviously increased and cell survival rate significantly declined. It is concluded that the specific siRNA distinctly inhibits the expression of bcr-abl fusion gene, and can induce K562 cell apoptosis. The combination of specific siRNA with P27 gene clone displays a synergy of inhibition and pro-apoptosis effects to K562 cells.

Role of mitochondria pathway in signal transduction of chronic myeloid leukemia / 中国实验血液学杂志

This study was aimed to investigate the role of mitochondria pathway in signal transduction of chronic myeloid leukemia (CML). After bcr3/abl2 antisense oligodeoxynucleotide (ASO) was introduced into CML cell line K562 cells by liposomal transfection, the cell viability was detected by MTT assay, the cell apoptosis was determined by flow cytometry (FCM), the mitochondrial membrane potential (DeltaPsi) was labeled by Rhodamine 123 and examined by FCM, and the expression of mitochondrial apoptosis signal transduction pathway related proteins cytochrome C was analyzed by Western blot. The results showed that after K562 cells were exposed to 2 micromol/L of bcr3/abl2 ASO for 24 hours, bcr3/abl2 ASO significantly inhibited cell viability with inhibitory rate of 65.7%, induced the apoptosis of K562 cell line with apoptotic rate of 16.9%, and decreased mitochondrial Deltapsi of K562 cells with the reducing rate of 38.33%, enhanced the expression of cytochrome C with increase of optical density value from 2.33 +/- 0.3 to 4.78 +/- 0.1 by laser photometric scanning. It is concluded that mitochondria pathway plays an important role in signal transduction of chronic myeloid leukemia by directing apoptotic signal transduction.

Effect of tyrosine-kinase Inhibitor on p15 gene transfected K562 cells / 中国实验血液学杂志

The objective of study was to investigate the combined effect of tyrosine-kinase inhibitor (imatinib) and p15 gene on the proliferation, cell cycle and apoptosis of chronic myeloid leukemia cell line K562. p15 gene was amplified from peripheral blood mononuclear cells by RT-PCR, and confirmed by DNA sequencing, then the recombinant p15-pcDNA3.1 vector was constructed and transfected into K562 cell line by Lipofectine. After screening with G418, p15-pcDNA3.1-K562 cell clone stably expressing P15 was isolated. P15 protein was identified by Western blot. The cell survival rate was determined by MTT, cell cycle and apoptosis were detected by flow cytometry. The results showed that partial deletion of p15 gene in K562 cells was verified by DNA sequencing, leading to the function of P15 protein to be lost. The expression of P15 protein can be detected by Western blot in p15-pcDNa3.1-K562 cells. A strong inhibition of cell proliferation was observed in p15-pcDNA3.1-K562 cells as compared with that of the control K562 cell. The cells of G(0)/G(1) phase in p15-pcDNA3.1-K562 cells increased apparently, and S phase cells declined signifcantly. Cell cycle was arrested in G(0)/G(1) phase. The percentage of apoptotic cells greatly increased after transfection with p15-pcDNA3.1-K562 cells combined with imatinib, and cell survival rate notably declined. It is concluded that the imatinib in combination with the expression of p15 gene has a synergistic effect on the inhibition of K562 cell proliferation and promotion of its apoptosis.

Survivin antisense oligonucleotide induces lymphoma cells apoptosis and sensitizes the cells to chemotherapy / 中华血液学杂志

<p><b>OBJECTIVE</b>To explore the effect of antisense oligodeoxynucleotide (ASODN) of survivin gene on apoptosis and chemotherapy sensitivity of lymphoma cell line Raji.</p><p><b>METHODS</b>Anti-survivin phosphorothioate ASODN was synthesized and transfected into Raji cells by lipofectin. MTT assay was used to detect cytotoxicity. Apoptosis was observed by fluorescence microscopy and flow cytometry. Survivin expression was determined by RT-PCR and Western-blotting.</p><p><b>RESULTS</b>(1) survivin ASODN inhibited the cells proliferation in a dose and time dependent manner. (2) A higher apoptosis rate (33.0%) could be induced in Raji cells by survivin ASODN as compared with that induced by the sense oligodeoxynucleotide (11.5%) (P < 0.05). (3) The expression of survivin mRNA and protein significantly decreased after treatment with survivin ASODN. (4) There was a significant increase of cell inhibition rate after exposure to the combination of survivin ASODN and Vm26 as compared to Vm26 or survivin ASODN alone (both P < 0.05).</p><p><b>CONCLUSION</b>Survivin ASODN is able to inhibit the proliferation of Raji cells, induce the apoptosis, and enhance the sensitivity of Raji cell to chemotherapy via specific down-regulation of survivin expression.</p>

Experimental research on tyrosine-kinase inhibitor STI571 and P21WAF gene clone to treat chronic myeloid leukemia / 中国实验血液学杂志

To explore the effect of a tyrosine-kinase inhibitor STI571 and P21(WAF) gene clone on the proliferation, cycle, apoptosis of leukemia cell line K562, P21(WAF) gene was obtained by RT-PCR, and its sequence was approved to be correct, then P21-pcDNA3.1 vector was constructed and transfected into K562 cell line. After selected with G418, P21-pcDNA3.1-K562 cell clone that stably expression P21(WAF) was isolated. P21(WAF) protein was identified by Western blot. The survival rate were tested by MTT. Cell cycle and apoptosis were tested by flow cytometry. The results showed that the expression of P21(WAF) protein could be detected by Western blot in P21-pcDNa3.1-K562 cells. A strong inhibition of cell proliferation was observed in P21-pcDNA3.1-K562 cells as compared with that of the control. The cells cycle were arrested in G(0)/G(1) phase. The percentage of apoptosis was declined slightly after P21-pcDNA3.1-K562 cells were combined with STI571, meanwhile its survival rate declined more slowly than that of K562 cell with STI571. In conclusion, P21(WAF) inhibits the proliferation of K562 cell, meanwhile slightly inhibits its apoptosis induced by STI571and decrease its sensitivity to STI571.