Anti-Leukemia Effect and Mechanism of Oridonin on Imatinib-Sensitive and Imatinib-Resistant K562 Cells / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To explore the molecular mechanism of resistance to imatinib in K562 cells(K562-R) and the anti-proliferative effect of oridonin (OR), as well as its mechanism in imatinib-sensitive and imatinib-resistant K562 cells (K562-S and K562-R cells).</p><p><b>METHODS</b>The expression of p-Lyn in K562-S and K562-R cells were detected by Western blot. The anti-proliferative effect of OR in K562-S and K562-R cells was assayed by MTT, the morphological changes were examined with microscope, the cell apoptosis was detected by flow cytometry, the expressions of BCL-2 and Akt/mTOR signaling pathway were detected by Western blot.</p><p><b>RESULTS</b>The over-expression of p-Lyn was detcected in K562-R cells, OR inhibited the proliferation of K562-S and K562-R cells and the value of ICwas 4.23±1.30, 4.97±2.23 µmol/L, respectively. The apoptotic rate was obviously enhanced after OR treatment for 24 h, compared with control group. OR down-regulated the expression of p-Lyn, mTOR signaling pathway and BCL-2 protein.</p><p><b>CONCLUSION</b>Over-expression of p-Lyn may be involved in the mechanism of resistance to imatinib. OR can inhibit the proliferation of K562-S and K562-R cells through down-regulating p-Lyn, inhibiting mTOR signaling pathway and down-regulating expression of BCL-2 protein.</p>

Anti-leukemia effect of oridonin on Ph(+) acute lymphoblastic leukemia cell SUP-B15 / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the anti-leukemia effect of oridonin on Ph(+) acute lymphoblastic leukemia (ALL) cell line SUP-B15.</p><p><b>METHODS</b>Human Ph(+) ALL cell line was cultured in vitro. The 50% inhibition concentration (IC(50)) of oridonin against SUP-B15 cell line was examined using modified MTT assay. The cellular morphologic changes were observed using a light microscope. The percent of apoptosis of SUP-B15 cell line after drug treatment was evaluated by flow cytometric analysis. The active levels of ABL kinase and its downstream Akt/mTOR, Raf/MEK/ERK, STAT5 signaling pathways and the expression levels of Bcl-2 and BAX were examined by Western blot.</p><p><b>RESULTS</b>Oridonin inhibited the growth of SUP-B15 cell line in both time- and dose-dependent manner with the IC(50) of oridonin as (7.08 ± 1.21) µmol/L after 72 h treatment. The cellular membrane of SUP-B15 cell line treated with oridonin became unsharp, some of them disintegrated. Oridonin induced apoptosis in SUP-B15 cell line with the apoptosis rates following 0, 5, 10 µmol/L oridonin treatment for 24 h were (6.67 ± 0.83)%, (18.30 ± 1.79)% and (37.63 ± 7.12)%, respectively. Oridonin inhibited activation of ABL kinase and its downstream Akt/mTOR, Raf/MEK/ERK and STAT5 signaling pathways, which were constitutively activated in SUP-B15 cell line, down-regulated the level of anti- apoptotic protein Bcl-2 and up-regulated the expression of pro-apoptotic protein Bax.</p><p><b>CONCLUSION</b>Oridonin exerted anti-leukemia effect in Ph(+)ALL cell line SUP-B15 by inhibiting the activation of ABL kinase and its downstream Akt/mTOR, Raf/MEK/ERK and STAT5 signaling pathways, down-regulating the expression of Bcl-2 and up-regulating the expression of BAX.</p>

The effect of knockdown of transcription factor SCL/TAL-1 gene on the erythroid differentiation in EPO-induced K562 cell line / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the role of transcript factor SCL/TAL-1 gene in the erythroid differentiation through the knockdown of SCL/TAL-1 mRNA by RNA interference.</p><p><b>METHODS</b>The plasmid of pTRIP-dU3-RNAiTALh-EF1a-GFP with SCL/TAL1 shRNA was transfected into EPO-induced K562 cell line with erythroid differentiation via lentiviral vector system and the expression of SCL/TAL-1 mRNA decreased. The plasmid pTRIP-dU3- RNAiluc-EF1-GFP expressing EGFP gene was as control. The mRNA levels of SCL/TAL-1 and erythroid related RhD, GPA, CD47 in the cell lines were detected by RT-PCR, and erythroid antigen CD71, CD235a were examined by flow cytometry.</p><p><b>RESULTS</b>(1) After 48 h of transfect, more than 95% of K562 cells were GFP positive, indicating the infection rate of the plasmids in the K562 cells more than 95%. (2) The results of RT-PCR showed SCL/TAL-1 mRNA expression in the K562 cell line of knockdown of SCL/TAL-1 was significantly lower than that in the control (P < 0.05). The mRNA levels of CD47 and RhD were also significantly lower, however, GPA decreased slightly in comparison with the control. (3) The expressions of CD71 and CD235a markedly reduced in the K562 cell line of knockdown of SCL/TAL-1 with positive rates as 10.4% and 76.5%, while the positive rates in the control as 94.3% and 83.6%.</p><p><b>CONCLUSION</b>Our findings suggested that transcription factor SCL/TAL-1 might play an positive role in erythroid differentiation.</p>