Effects of arsenic trioxide administration styles on leukocytosis / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To study the effects of constantly slow intravenous arsenic trioxide (As2O3) infusion regimen on decreasing leukocytosis in vivo and in vitro.</p><p><b>METHODS</b>Three kinds of leukemia cells, NB4, K562, and acute promyelocytic leukemia (APL) cells, were cultured in the media with constant concentration and varying concentrations of As2O3 respectively for 24 hours. Seventy-five patients were enrolled in two groups randomly. In trial group, 37 patients received continuously slow intravenous As2O3 infusion regimen for 24 hours with an infusion rate of 8 drips per minute and total infusion duration of about 18-21 hours daily. In control group, 38 patients received routine regimen with an infusion rate of 45-55 drips per minute and total infusion duration of about 2-3 hours daily for 24 hours. The daily As2O3 dosage was 0. 16 mg/kg. The intracellular arsenic concentration was measured by atomic fluorescence assay. The apoptosis rate of cells, CD33- CD11b+ cells, and CD33+ CD11b- cells were monitored by flow cytometry.</p><p><b>RESULTS</b>The apoptosis rates of NB4, K562, and APL leukemia cells in the media with constant As2O3 concentration were 56.6% +/- 2.4%, 27.6% +/- 3.1%, and 52.2% +/- 2.8%, respectively, which were significantly higher than those with changing As2O3 concentration (23.2% +/- 2.1%, 11.0% +/- 2.5%, and 21.0% +/- 2.5%, respectively, P < 0.01). The apoptosis rates of APL, M2 type acute myeloid leukemia (AML-M2), and chronic myeloid leukemia (CML) patients in the trial group (28.5% +/- 1.9%, 9.5% +/- 0.6%, and 12.5% +/- 1.8%) were also significantly higher than those in control group (8.5% +/- 2.2%, 2. 9% +/- 0.8%, and 4.5% +/- 1.2%; P < 0.05). The ratios of CD33 CD11b- and CD33- CD11b+ cells in control group were significantly higher than those in trial group.</p><p><b>CONCLUSION</b>The continuously slow intravenous As2O3 infusion regimen can obtain high efficiency of apoptosis and low differentiation proportion, relieve leukocytosis, and gain maximal therapeutic benefit.</p>

Effects of protein tyrosine kinase, protein tyrosine phosphatase and protein kinase C on the apoptosis of arsenic trioxide treated NB4 cells and human cortex neurons / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the effects of protein tyrosine kinase (PTK), protein tyrosine phosphatase (PTP) and protein kinase C (PKC) on apoptosis and observe the changes of cytosolic calcium ([Ca(2+)]i) of arsenic trioxide (As2O3) treated human leukemia cells NB4 and cortex neurons.</p><p><b>METHODS</b>[Ca(2+)]i of NB4 cells and cortex neurons was probed with Fluo-3/AM, its changes were assayed with laser confocal microscopy in real-time after As2O3 treatment at different concentrations, the effects of PTK and PTP and the activation of PKC on these changes with confocal microscopy and phosphorus radioisotope assay. DNA ladders of NB4 cells and cortex neurons after exposed to As2O3 were observed.</p><p><b>RESULTS</b>As2O3 at 1 micromol/L could remarkably increase the [Ca(2+)]i of NB4 cells but had no effects on neurons. Vanadate, a kind of PTP inhibitor, could promote the increase of [Ca(2+)]i treated by 2, 5, 10 micromol/L As2O3 in a dose-dependent manner. The mean total increase rates at 240 seconds after exposed to As2O3 at different concentrations were (6.5 +/- 2.3)%, (21.7 +/- 2.1)%, (49.2 +/- 2.5)% for NB4 cells, and (6.7 +/- 2.1)%, (19.4 +/- 2.5)%, (52.3 +/- 2.7)% for cortex neurons, respectively. Genistein, a kind of PTK inhibitor, could decrease the increase of [Ca(2+)]i treated by 2, 5, 10 micromol/L As2O3 in a dose-dependent manner. The mean total inhibited rates at 240 seconds after As2O3 treatment at different concentrations were (6.7 +/- 2.9)%, (25.6 +/- 2.5)%, (52.2 +/- 3.5)% for NB4 cells, and (7.8 +/- 3.1)%, (18.1 +/- 2.8)%, (51.3 +/- 3.3)% for cortex neurons, respectively. The activation of PKC began to increase as exposed to As2O3 at 1 micromol/L for 3 h, and kept rising continuously in NB4 cells and at 24 h DNA ladders emerged. However, none of the above results was found in human cortex neurons, but when exposed to 2 micromol/L As2O3, the activation of PKC and DNA ladders did emerge in neurons.</p><p><b>CONCLUSIONS</b>The phosphorylation and dephosphorylation of PTK and PTP participated in nonspecific apoptosis signal transduction pathway related to As2O3, and accompanied with PKC activation. The [Ca(2+)]i elevation was closely related to increased PKC activation. There existed difference in dose tolerances to As2O3 between NB4 cell and cortex neurons.</p>