The autophagy induced by curcumin via MEK/ERK pathway plays an early anti-leukemia role in human Philadelphia chromosome-positive acute lymphoblastic leukemia SUP-B15 cells.

BACKGROUND: Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL) is triggered by BCR/ABL tyrosine kinase which activates the downstream signaling pathways, such as Akt/mTOR, RAF/MEK/ERK, and STAT5 pathways. Curcumin has been shown to have inhibitory effects on cancers by inducing apoptosis and autophagy. We demonstrated that curcumin inhibited activation of Akt-mTOR, ABL/STAT5 pathways, inhibited cell proliferation, and induced apoptosis in Ph + ALL cells. Experiments here, were conducted to determine whether autophagy via MEK/ERK pathway involved in anti-leukemia effect of curcumin in Ph + ALL. MATERIALS AND METHODS: Ph + ALL cell line SUP-B15 was treated with curcumin. Cytotoxic activity of curcumin was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. Signaling protein and specific maker of autophagy and conversion of LC3-I to LC3-II were determined by Western blot analysis. Cell apoptosis was determined by flow cytometry. RESULTS: Curcumin treatment up-regulated the activation of RAF/MEK/ERK at 4 h and 8 h after curcumin exposure in SUP-B15 cells, curcumin treatment induced autophagy at exactly 4 h and 8 h after curcumin exposure. Curcumin exerted cytotoxic activity against SUP-B15 cells at 4 h and 8 h, which was independent of apoptosis. MEK specific inhibitor U0126 inhibited the occurrence of autophagy, and then blocked curcumin-induced cytotoxicity at 4 h and 8 h. CONCLUSIONS: Curcumin induce autophagic cell death in SUP-B15 cells via activating RAF/MEK/ERK pathway. These findings suggest that autophagic mechanism contribute to the curcumin-induced early SUP-B15 cell death, and autophagy is another anti-leukemia mechanism of curcumin.

[Anti-Leukemia Effect and Mechanism of Oridonin on Imatinib-Sensitive and Imatinib-Resistant K562 Cells].

OBJECTIVE: 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). METHODS: 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. RESULTS: 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 IC50 was 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. CONCLUSION: 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.

[Effect of tanshinone II A on leukemia cell line K562].

OBJECTIVE: To determine the anti-proliferative effect of Tanshinone II A (TAT) on leukemia K562 cell line and its mechanism. METHODS: The proliferation of K562 cell line was detected by MTT assay. The morphological changes of the cells were examined with light microscope. The cell apoptosis was detected by flow cytometry. The expressions of BCL-2, BAX and m-TOR signaling pathway were examined by Western blot assay. RESULTS: TAT inhibited the proliferation of K562 cell line, with a value of IC50 (7.75 +/- 2.47) micromol/L after treatment for 96 h. Significant morphological changes were found after incubation of the cells for 24 h. The apoptotic rate accelerated after TAT treatment for 24 h compared with the controls. TAT down-regulated the expression of mTOR signaling pathway and BCL-2 protein, and up-regulated proapoptotic protein BAX. CONCLUSION: TAT can inhibit the proliferation of K562 cells through down-regulating mTOR signaling pathway, inducing apoptosis.

[Anti-leukemia effect of oridonin on T-cell acute lymphoblastic leukemia].

OBJECTIVE: To investigate the antileukemia effect of oridonin on T-cell acute lymphoblastic leukemia cell line CEM. METHODS: Human T-cell acute lymphoblastic leukemia cell line CEM was cultured in vitro. The 50% inhibition concentration (IC50) of oridonin against CEM cells was examined using modified MTT assay. The cellular morphologic changes were observed using a light microscope. The percent of apoptosis of CEM cells after drug treatment was evaluated by flow cytometric analysis. The active levels of AKT/mTOR, RAF/MEK/ ERK, STAT5 signaling pathways and the expression levels of Bcl-2 and BAX were examined by Western blot. RESULTS: Oridonin inhibited the growth of CEM cells in time- and dose dependent manner and the ICs0 of oridonin was (7. 37± 1. 99) µmol/L after 72 h treatment. The cellular membrane of CEM cells treated with oridonin became unsharp, some of them disintegrated. Oridonin induced apoptosis in CEM cells and the percent of apoptosis rate after 0, 5, 7.5, 10 µmol/L oridonin treatment for 24 h were (4. 8±2. 11)%, (19.03±12.54)% ,(40.27± 3.31) / and (57. 23 ± 6. 69)% respectively. Oridonin inhibited activation of mTOR, P70S6, 4EBP1, RAF. ERK and STAT5 signaling protein, which were constitutively activated in CEM cells, however, oridonin had no inhibitory effect on AKT kinase. Oridonin down-regulated the level of anti apoptotic protein Bcl-2 and up-regulated the expression of pro-apoptotic protein Bax. CONCLUSION: Oridonin exerted antileukemia effect in CEM cells by inhibiting the activation of mTOR/P70/4EBP1, RAF/ERK and STATS signaling pathways, down-regulating the expression of Bel-2 and up-regulating the expression of BAX.

[Multidrug resistant gene MDR1 contributes to development of imatinib-resistance in Ph (+) acute lymphoblastic leukemia cell line SUP-BS15RI].

OBJECTIVE: To investigate the contribution of multidrug-resistant gene MDR1 to development of imatinib-resistance in Ph(+) acute lymphoblastic leukemia cell line SUP-B15/RI. METHODS: RT-PCR was used to examine MDR1 mRNA levels, cytotoxic effects of imatinib (IM), daunorubicin (DNR), vincristine (VCR), etoposide (VP-16) and the synergetic antiproliferation with P-gp inhibitor verapamil on sensitive SUP-B15 and SUP-B15/RI cell lines were detected by the MTT assay. The P-gp function was measured by flow cytometry. RESULTS: Increased expression of MDR1 gene in SUP-B15/RI than that of SUP-B15 cell line (P < 0.05) was observed when detected with RT-PCR. The IC50 values of SUP-B15/RI cell line inhibited by IM, DNR, VCR, VP-16 for 72 hours was higher than that of SUP-B15 (P < 0.05) and the resistant factor (RF) was (20.52 +/- 2.34), (10.33 +/- 1.88), (9.78 +/- 1.27), (3.84 +/- 0.69) respectively. The IC50 values of IM, DNR, VCR, VP-16 combined with P-gp inhibitor verapamil were decreased in SUP-B15/RI cells (P < 0.05), reversal of drug resistance was (1.44 +/- 0.43), (3.20 +/- 0.17), (1.44 +/- 0.12), (1.33 +/- 0.14) respectively. The activity of P-gp in SUP-B15/RI measured by flow cytometry was higher than that of P-gp in SUP-B15/RI cell line. CONCLUSION: The overexpression of MDR1 mRNA and higher activity of P-gp is partially responsible for acquiring of imatinib resistance in SUP-B15/RI cell line. P-gp inhibitor verapamail can partially restored the sensitivity of the SUP-B15/RI cell line to anticancer agents.

[Anti-leukemia effect of oridonin on Ph(+) acute lymphoblastic leukemia cell SUP-B15].

OBJECTIVE: To investigate the anti-leukemia effect of oridonin on Ph(+) acute lymphoblastic leukemia (ALL) cell line SUP-B15. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

[The effect of knockdown of transcription factor SCL/TAL-1 gene on the erythroid differentiation in EPO-induced K562 cell line].

OBJECTIVE: 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. METHODS: 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. RESULTS: (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%. CONCLUSION: Our findings suggested that transcription factor SCL/TAL-1 might play an positive role in erythroid differentiation.

[Anti-tumor effect of tanshinone II A, tetrandrine, honokiol, curcumin, oridonin and paeonol on leukemia cell lines].

OBJECTIVE: To study the anti-tumor effect of tanshinon II A, tetrandrine, honokiol, curcumin, oridonin and paeonol on leukemia cell lines SUP-B15, K562, CEM, HL-60 and NB4. METHODS: To study the anti-tumor effect of tanshinone II A, tetrandrine, honokiol, curcumin, The leukemia cell lines were exposed to the six Chinese herbal components for 96 hours. The proliferative inhibitory effects were detected with MTT and described by IC50 value. RESULTS: Tanshinone II A inhibited the proliferations of SUP-B15, K562, CEM, HL-60 and NB4 cell lines, with HL-60 showing the least impact. Tetrandrine, honokiol, curcumin and oridonin inhibited the proliferations of SUP-B15, K562, CEM, HL-60 and NB4 cell lines and there was no significant difference between the cell lines. Paeonol did not have significant inhibitory effect on leukemia cell lines. CONCLUSION: Tetrandrine, honokiol, curcumin and oridonin inhibit the proliferation of five cell lines SUP-B15, K562, CEM, HL-60, NB4, and the effects are similar, which means that their anticancer effects are quite broad. Tanshinone II A has better anti-leukemia effects on SUP-B15, K562, CEM, NB4 than on HL-60. The effect of paeonol against leukemia cell lines is poor.