Autophagy Inhibition Potentiates the Anticancer Effects of a Bendamustine Derivative NL-101 in Acute T Lymphocytic Leukemia.

Acute T lymphocytic leukemia (T-ALL) is an aggressive hematologic resulting from the malignant transformation of T-cell progenitors. Drug resistance and relapse are major difficulties in the treatment of T-ALL. Here, we report the antitumor potency of NL-101, a compound that combines the nitrogen mustard group of bendamustine with the hydroxamic acid group of vorinostat. We found NL-101 exhibited efficient antiproliferative activity in T-ALL cell lines (IC50 1.59-1.89 µM), accompanied by cell cycle arrest and apoptosis, as evidenced by the increased expression of Cyclin E1, CDK2, and CDK4 proteins and cleavage of PARP. In addition, this bendamustine-derived drug showed both a HDACi effect as demonstrated by histone hyperacetylation and p21 transcription and a DNA-damaging effect as shown by an increase in γ-H2AX. Intriguingly, we found that NL-101-induced autophagy in T-ALL cells through inhibiting Akt-mTOR signaling pathway, as indicated by an increase in LC3-I to LC3-II conversion and decrease of p62. Furthermore, inhibition of autophagy by 3-methyladenine increased apoptotic cell death by NL-101, suggesting a prosurvival role of autophagy. In summary, our finding provides rationale for investigation of NL-101 as a DNA/HDAC dual targeting drug in T-ALL, either as a single agent or in combination with autophagy inhibitors.

A novel SAHA-bendamustine hybrid induces apoptosis of leukemia cells.

Hybrid anticancer drugs are of great therapeutic interests as they can potentially overcome the deficiencies of conventional chemotherapy drugs and improve the efficacy. Many studies have revealed that the combination of histone deacetylase inhibitors (HDACi) and alkylating agents have synergistic effects. We reported a novel hybrid NL-101, in which the side chain of bendamustine was replaced with the hydroxamic acid of HDACi vorinostat (SAHA). NL-101 exhibited efficient anti-proliferative activity on myeloid leukemia cells especially Kasumi-1 and NB4 cells, accompanied by S phase arrest and caspase-3 dependent apoptosis. Importantly, it presented both the properties of HDAC inhibition and DNA damaging, as assessed by the acetylation of histone H3 and DNA double-strand breaks marker γ-H2AX. NL-101 also down-regulated the expression of anti-apoptotic protein Bcl-xL which was involved in the mitochondrial death pathway. Meanwhile, NL-101 induced apoptosis and DNA damage in primary cells from acute myeloid leukemia (AML) patients. NL-101 treatment could significantly prolong the survival time of t(8;21) leukemia mice with enhanced efficacy than bendamustine. These data demonstrate that NL-101 could be a potent and selective agent for leukemia treatment.

Synthesis and anticancer evaluation of thiazolyl-chalcones.

Thirty-seven (E)-1-(4-methyl-2-arylaminothiazol-5-yl)-3-arylprop-2-en-1-ones were synthesized via Claisen-Schmidt condensation of 1-(4-methyl-2-(arylamino)thiazol-5-yl)ethanone with the corresponding arylaldehydes. All these thiazolyl-chalcones were characterized and evaluated by MTT assay on human cancer cell lines BGC-823, PC-3, NCI-H460, BEL-7402 in vitro. Compounds 5, 8, 26, 37 and 41 are effective against cancer cell lines with IC(50)s below 10 µM. The antitumor activity in ICR mice bearing sarcoma 180 tumors indicates compounds 10 and 41 have moderate in vivo activity with 22-25% tumor-weight inhibition.

Synthesis and anticancer evaluation of alpha-lipoic acid derivatives.

alpha-Lipoic acid derivatives were synthesized and evaluated for their in vitro anticancer activities against NCI-460, HO-8910, KB, BEL-7402, and PC-3 cell lines. The results, for most compounds exhibited dose-dependent inhibitory property and several compounds had good inhibitions at the dose of 100 microg/mL. Compound 17 m was further selected for in vivo evaluation against S180 xenograft in ICR mice, which had 24.7% tumor-weight inhibition through intragastric administration of 200mg/kg of body weight. Moreover, the LD(50) in mice for 17 m through ig exceeded 1000 mg/kg of body weight.

[Effects of cysteinyl receptor agonist and antagonists on rat primary cortical neurons].

OBJECTIVE: To determine the effect of cysteinyl receptor agonist leukotriene D(4) (LTD(4)) and its antagonists on rat primary neurons. METHODS: In the primarily cultured rat cortical neurons, the neuron injury was evaluated by measuring intracellular calcium, 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) reduction, and propidium iodide (PI) and Hoechst 33258 staining. The in vitro ischemic injury was induced by oxygen-glucose deprivation (OGD) for 1.5 h and reperfusion for 24 h. RESULT: LTD(4) (0.01-1 micromol/L) did not induce the elevation of intracellular calcium, neuron viability changes and neuron death. OGD-induced injury was not significantly ameliorated by the CysLT(1) receptor antagonists, pranlukast (0.2-10 micromol/L) and montelukast (0.2-10 micromol/L), as well as by the CysLT(1)/CysLT(2) receptor non-selective antagonist, BAY u9773 (0.02-1 micromol/L). CONCLUSION: Neither agonist nor antagonists of cysteinyl receptors have the effects on the viability and ischemic-like injury in rat primary neurons.

Baicalin attenuates oxygen-glucose deprivation-induced injury via inhibiting NMDA receptor-mediated 5-lipoxygenase activation in rat cortical neurons.

The flavonoid baicalin exerts neuroprotective effects but the mechanism is not fully clarified. On the other hand, 5-lipoxygenase (5-LOX) activation is involved in ischemic neuronal injury. In this study, we determined whether baicalin protects rat cortical neurons against oxygen-glucose deprivation (OGD)-induced ischemic-like injury, if so, whether this effect relates to 5-LOX activation. After the neurons were injured by 1.5-h OGD and 24-h recovery, their viability reduced and necrosis occurred; these injuries were attenuated by baicalin (1 and 5microM) as well as caffeic acid (a 5-LOX inhibitor, 5 and 25microM) and MK-801 (an NMDA receptor antagonist, 1-10microM). OGD-induced 5-LOX translocation to the nuclear envelope as detected by immunoblotting, immunocytochemistry and 5-LOX transfection; this translocation was inhibited by baicalin (5microM) and MK-801 (5microM) but not by caffeic acid (5microM). During 0.5- to 2-h recovery after 1.5-h OGD, the production of 5-LOX metabolites, cysteinyl leukotrienes, was increased; this increased production was inhibited by baicalin and MK-801, while both the increased and baseline production were inhibited by caffeic acid. In addition baicalin and MK-801, not caffeic acid, inhibited glutamate-induced elevation of intracellular calcium. These results indicate that baicalin attenuates ischemic-like injury in the neurons, and this effect partly relates to the inhibition of NMDA receptor-mediated 5-LOX activation.

Activation of 5-lipoxygenase after oxygen-glucose deprivation is partly mediated via NMDA receptor in rat cortical neurons.

5-Lipoxygenase (5-LOX) is the enzyme metabolizing arachidonic acid to produce pro-inflammatory leukotrienes. We have reported that 5-LOX is translocated to the nuclear envelope after ischemic-like injury in PC12 cells. In the present study, we determined whether 5-LOX is activated (translocation and production of leukotrienes) after oxygen-glucose deprivation (OGD) in primary rat cortical neurons; if so, whether this activation is mediated by NMDA receptor. After OGD, 5-LOX was translocated to the nuclear envelope as detected by immunoblotting, immunostaining and green fluorescent protein-5-LOX transfection. 5-LOX metabolites, cysteinyl-leukotrienes (CysLTs) but not leukotriene B4, in the culture media were increased 0.5-1.5 h after recovery. Similarly, NMDA (100 microm) also induced 5-LOX translocation, and increased the production of CysLTs during 0.5-1 h NMDA exposure. Both OGD and NMDA reduced neuron viability. NMDA receptor antagonist MK-801 inhibited almost all the responses to OGD and NMDA; whereas 5-LOX activating protein inhibitor MK-886 and 5-LOX inhibitor caffeic acid inhibited the reduction of neuron viability and the production of CysLTs, but did not affect 5-LOX translocation. From these results, we conclude that OGD can activate 5-LOX in primary rat cortical neurons, and that this activation may be partly mediated via activating NMDA receptor.

Minocycline protects PC12 cells against NMDA-induced injury via inhibiting 5-lipoxygenase activation.

Recently, we have reported that minocycline, a semi-synthetic tetracycline with neuroprotective effects, inhibits the in vitro ischemic-like injury and 5-lipoxygenase (5-LOX) activation in PC12 cells. In the present study, we further determined whether minocycline protects PC12 cells from excitotoxicity via inhibiting 5-LOX activation. We used N-methyl-d-aspartate (NMDA, 200 microM) to induce early (exposure for 6 h) and delayed (exposure for 6 h followed by 24 h recovery) injuries. We found that NMDA receptor antagonist ketamine, 5-LOX inhibitor caffeic acid and minocycline concentration dependently attenuated NMDA-induced early and delayed cell injuries (viability reduction and cell death). However, only ketamine (1 microM) inhibited NMDA-evoked elevation of intracellular calcium. In addition, immunohistochemical analysis showed that NMDA induced 5-LOX translocation to the nuclear membrane after 1- to 6-h exposure which was confirmed by Western blotting, indicating that 5-LOX was activated. Ketamine, caffeic acid and minocycline (each at 1 microM) inhibited 5-LOX translocation after early injury. After delayed injury, PC12 cells were shrunk, and 5-LOX was translocated to the nuclei and nuclear membrane; ketamine, caffeic acid and minocycline inhibited both cell shrinking and 5-LOX translocation. As a control, 12-LOX inhibitor baicalein showed a weak effect on cell viability and death, but no effect on 5-LOX translocation. Therefore, we conclude that the protective effect of minocycline on NMDA-induced injury is partly mediated by inhibiting 5-LOX activation.

[Homeostatic conditions affect the protective effect of edaravone on ischemic injury in neurons].

OBJECTIVE: To determine whether homeostatic conditions (pH, glycine or ion concentration) affect the protective effects of edaravone on ischemic injury in rat cortical neurons. METHODS: In cultured rat cortical neurons, the compositions in the experimental solutions were changed to mimic the disturbance of homeostasis after cerebral ischemia. In vitro ischemic injury was induced by oxygen-glucose deprivation (OGD) for 3 h and reperfusion for 12 h, and the neuron injury was evaluated by 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) reduction assay and lactate dehydrogenase (LDH) release. Effect of edaravone on OGD injury was observed in different experimental solutions. RESULT: In weak alkalified solution (pH 7.8) or the solution containing glycine (10 micromol/L), OGD injury became more serious; but in weak acidic (pH 6.5) or higher Mg(2+) (1.8 mmol/L) solutions, OGD injury was attenuated. Edaravone (1 micromol/L) reversed the injury in the solutions with pH 6.1,7.4 and 7.8 or the solution containing glycine, but did not show protective effect in the solution with pH 6.5 and the higher Mg(2+) or lower Ca(2+) solution. CONCLUSION: The changes of homeostatic conditions affect the severity of ischemic injury of neurons and the protective effect of edaravone.

Distribution of cysteinyl leukotriene receptor 2 in human traumatic brain injury and brain tumors.

AIM: To determine the distribution of cysteinyl leukotriene receptor 2 (CysLT2), one of the cysteinyl leukotriene receptors, in human brains with traumatic injury and tumors. METHODS: Brain specimens were obtained from patients who underwent brain surgery. CysLT2 in brain tissues was examined using immunohistochemical analysis. RESULTS: CysLT2 was expressed in the smooth muscle cells (not in the endothelial cells) of arteries and veins. CysLT2 was also expressed in the granulocytes in both vessels and in the brain parenchyma. In addition, CysLT2 was detected in neuron- and glial-appearing cells in either the late stages of traumatic injury or in the area surrounding the tumors. Microvessels regenerated 8 d after trauma and CysLT2 expression was recorded in their endothelial cells. CONCLUSION: CysLT2 is distributed in vascular smooth muscle cells and granulocytes, and brain trauma and tumor can induce its expression in vascular endothelial cells and in a number of other cells.

GM1 stabilizes expression of NMDA receptor subunit 1 in the ischemic hemisphere of MCAo/reperfusion rat.

OBJECTIVE: To determine the protective effect of monosialoganglionside (GM1) and evaluate the influence of GM1 on expression of N-methyl-D-aspartate receptor subunit 1 (NMDAR1) in Sprague-Dawley (SD) rats with focal cerebral ischemia-reperfusion (I/R). METHODS: Left middle cerebral artery (MCA) was occluded by an intraluminal suture for 1 h and the brain was reperfused for 72 h in SD rats when infarct volume was measured, GM1 (10 mg/kg) was given ip (intraperitoneally) at 5 min (group A), 1 h (group B) and 2 h (group C) after MCA occlusion (MCAo). Expression of NMDAR1 was detected by Western blot at various time after reperfusion (4 h, 6 h, 24 h, 48 h and 72 h) in ischemic hemispheres of the rats with or without GM1 administered. RESULTS: (1) Adjusted relative infarct volumes of groups A and B were significantly smaller than that of group C and the control group (P<0.01 and P<0.05, respectively). (2) Expression level of NMDAR1 was temporally high at 6 h after reperfusion, and dipped below the normal level at 72 h after reperfusion. GM1 at 5 min after MCAo significantly suppressed the expression of NMDAR1 at 6 h after reperfusion (P<0.05 vs the control). At 72 h after reperfusion, the NMDAR1 expression level of rats treated with GM1 administered (at 5 min or 2 h after MCAo) was significantly higher than that of the control (P<0.05). CONCLUSION: GM1 can time-dependently reduce infarct volume in rats with focal cerebral I/R partly through stabilizing the expression of NMDAR1.

Monosialoganglioside protected ischemic rat hippocampal slices through stabilizing expression of N-methyl-D-aspartate receptor subunit.

AIM: To determine direct protective effect of monosialoganglioside (GM1) on hippocampal slices after oxygen-glucose deprivation and reperfusion (OGD/RP), and investigate the influence on the expression of N-methyl-D-aspartate receptor subunit 1 (NMDAR1) in those hippocampal slices. METHODS: Injury of hippocampal slices and protective effects of GM1 were detected by 2,3,5-triphenyltetrazolium chloride (TTC) staining, toluidine blue staining, and transmission electron microscopy of rat hippocampal slices. Expression of NMDAR1 was detected by Western blot. RESULTS: (1) GM1 at 1.0 micromol/L was the most effective concentration to preserve the TTC staining of the hippocampal slices after OGD/RP (P<0.05), and the next was GM1 at 10.0 micromol/L (P<0.05). (2) Toluidine blue staining and transmission electron microscopy showed GM1 protected the injuried hippocamal slices after OGD/RP. (3) GM1 downregulated the temporally high expression of NMDAR1 in the hippocampal slices immediately after a 25-min OGD and prevented the over low expression of NMDAR1 after a 30-min reperfusion. CONCLUSION: GM1 could protect injuried rat hippocampal slices after OGD/RP through stabilizing the expression of NMDAR1.

[Reversing effect of histamine on neuron death induced by N-methyl-D-aspartate].

OBJECTIVE: To determine the effect of histamine on N-methyl-D-aspartate (NMDA) induced neuron death and to elucidate its mechanism. METHODS: The primary cortical cell culture was adopted. Neuron morphology and MTT assay were used to evaluate the drugs effects. RESULT: Histamine at doses of 10(-4) 10(-6) 10(-7) 10(-8) mol/L reversed the neuron death induced by NMDA (50 micromol/L) for 3 h. The protection of histamine peaked at doses of 10(-4) mol/L and 10(-7)mol/L. The effect of histamine of 10(-7) mol/L was reversed only by cimetidine an H(2)receptor antagonist. However, the effect of histamine of 10(-4) mol/L was reversed only by pyrilamine but not cimetidine. CONCLUSION: Histamine could reduce neuron death induced by NMDA; its protection at a low dose might be mediated by H(2)receptor, and at a high dose by H(1)receptor.

[Study on protective effect of monosialoganglioside (GM1) on injury induced by oxygen glucose deprivation/reperfusion in rat hippocampal slices].

AIM: To investigate the protective effect of monosialoganglioside (GM1) on injury induced by oxygen glucose deprivation/reperfusion (OGD/Rep) in rat hippocampal slices. METHODS: The protective effects of GM1 on hippocampal slices after OGD/Rep were observed by detecting the light transmittance (LT) changes of rat hippocampal slices and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining of rat hippocampal slices. RESULTS: (1) In four groups treated with 0 (control), 0.1, 1.0, 10 micromol/L GM1, the peak of light transmittance (LT) in the slices treated with 1.0 micromol/L GM1 was significantly lower than that of the control and the group treated with 0.10 micromol/L GM1 (P < 0.01, ANOVA), while the peak of LT in the slices treated with 10.0 micromol/L GM1 was significantly lower than that of the other groups (P < 0.01, ANOVA). The time to reach the peak of LT in four groups was significantly different from each other (P < 0.05, Kruskal-Wallis test). The time to reach the peak of LT in the group treated with 1 micromol/L GM1 was the significantly longer than that in the control (P < 0.01, Mann-Whitney U test). (2) There was characteristic dose-response relationship between GM1 and TTC staining of rat hippocampal slices. In the five groups, treated with 0 (control), 0.01, 0.1, 1.0, 10 micromol/L GM1 respectively, TTC staining in the group treated with 1 micromol/L GM1 was the deepest (P < 0.05 vs. control, 0.01 and 0.1 micromol/L GM1 group, ANOVA), and the next was in the group treated with 10 micromol/L GM1 (P < 0.05 vs. control and 0.01 micromol/L GM1 group, ANOVA). CONCLUSION: GM1 could protect injury induced by OGD/Rep in rat hippocampal slices effectively in vitro.

[An improved quantitative method for evaluation of ischemic injury and neuroprotection in mouse brain slices].

OBJECTIVE: To establish a simpler and more accurate method for evaluating in vitro ischemic injury and neuroprotective effects of drugs through improving experimental instrument and quantitative index in mouse brain slices. METHODS: An incubation instrument was developed and its application tested. 2,3,5-triphenyltetrazolium chloride (TTC) was used as a substrate to biosynthesize formazan standard in mouse brain slices, and formazan was isolated, purified and identified. Ischemic injury of mouse brain slices was induced by oxygen/glucose deprivation (OGD), the produced formazan from TTC in the cortex and striatum was measured at 490 nm spectrophotometrically. Edaravone and ONO-1078 were added into the incubation medium to observe their neuroprotective effects. RESULT: The incubation instrument worked well for incubating brain slices and obtaining stable results efficiently. Standard formazan was biosynthesized and purified with a purity of 99.3%, and showed a linear range of 0.05 - 1 mg/ml in absorbance at 490 nm (r=0.9997). OGD decreased formazan production in the cortex and striatum in a duration-dependent manner. Edaravone (0.01 to 1 micromol/L) recovered OGD-induced decrease of formazan production, but ONO-1078 showed no effect. CONCLUSION: The incubation instrument and quantitative measurement of formazan developed in this study are efficient,accurate and simple for evaluating ischemic injury and neuroprotection,which can be used in screening of neuroprotective drugs in vitro.