[Effects of arsenic trioxide combined with bortezomib on proliferation and apoptosis of K562 cells and their mechanism].

This study was aimed to investigate the effect of arsenic trioxide (As(2)O(3)) alone and in combination with bortezomib (Bor) on proliferation and apoptosis of leukemia cell line K562, and to analyze the potential mechanism. K562 cells were treated with different concentrations of As(2)O(3) or Bor (alone or combination) for 24, 48 h. MTT method was used to detect the cell proliferation. After K562 cells were treated with 0.5 µmol/L As(2)O(3) alone or in combination with 10 nmoL/L Bor, the apoptosis rate and cell cycle were measured by flow cytometry, and the activity of NF-κB was analyzed by SP immunohistochemistry. The results indicated that the different concentrations of As(2)O(3) and Bor could inhibit the K562 cell proliferation in a time- and dose-dependent manners (P < 0.05). The IC(50) of Bor and As(2)O(3) in 48 h were 20 nmol/L and 0.6 µmol/L respectively. When K562 cells were treated with As(2)O(3) or Bor alone for 24 h, the apoptotic rate of K562 cells increased, and the apoptotic rate in combination group was higher than that in As(2)O(3) or Bor group. The cells were apparently arrested in G(2)/M phase in Bor group and G(0)/G(1) phase in As(2)O(3) group. The activity of NF-κB decreased significantly in As(2)O(3) or Bor group (P < 0.05), this effect was most significant in the combination group (P < 0.01). It is concluded that both As(2)O(3) and Bor can inhibit the proliferation and induce apoptosis of K562 cells, a synergistic effect can be observed when a low dose of As(2)O(3) combined with low dose of Bor. The different cell cycle block site and the decrease of activity of NF-κB may be one of the mechanisms underlying their synergic effect.

[Effects of hyperbaric oxygenation combined with As(2)O(3) on proliferation of K562 cells and associated mechanism].

This study was aimed to explore the effects of hyperbaric oxygenation (HBO) alone or combined with As(2)O(3) on proliferation, apoptosis and expression of HIF-1a, VEGF, caspase-3 mRNA of K562 cells, and the molecular mechanism of As(2)O(3) enhancing the anti-leukemic effect of HBO so as to provide a scientific basis for clinical treatment of chronic myeloid leukemia. The effects of drugs on proliferation of K562 cells was assayed by MTT method, the apoptosis rate of K562 cells was detected by flow cytometry with Annexin V/PI double staining, the expressions of HIF-1a, VEGF, caspase-3 mRNA of K562 cells were determined by real-time quantitative PCR. The results showed that as compared with As(2)O(3) alone, HBO combined with As(2)O(3) could increase inhibitory rate of K562 cell proliferation, and enhance apoptotic effect, obviously down-regulate expressions of HIF-1a and VEGF mRNA, up-regulate expression of caspase-3 mRNA. The effect of HBO combined with As(2)O(3) was higher then effect of As(2)O(3) alone, and their effects were synergistic (P < 0.05). It is concluded that HBO combined with As(2)O(3) can increase the expression of caspase 3 mRNA and decrease the expression of HIF-1a and VEGF mRNA, which may be one of molecular mechanisms underlying their synergistic antileukemia efficacy.

[Expression and significance of B cell-activating factor of TNF family (BAFF) and B cell lymphoma/leukemia-2 (BCL-2) in multiple myeloma].

This study was aimed to explore the expression of B cell-activating factor of TNF family (BAFF) and B cell lymphoma/leukemia-2 (BCL-2) in bone marrow mononuclear cells (BMMNC) of multiple myeloma (MM) and the significance of BAFF and BCL-2 for occurrence, development and prognosis of MM. The bone marrow of 40 cases of MM and 10 healthy persons was collected, the mononuclear cells (MNC) were isolated, the expression of BAFF and BCL-2 mRNA in BMMNC was detected by real-time PCR; the plasma was simultaneously collected and the ß2-MG level was determined; the clinical staging of MM patients was performed according to Durie-Salmon (D-S) staging criterion. The results indicated that the expression level of BAFF and BCL-2 mRNA in MM patients increased, as compared with normal controls, the difference was statistical significant (p < 0.05); the expression level of BAFF and BCL-2 mRNA in plateau stage after treatment obviously decreased. The expression level of BAFF and BCL-2 mRNA in relapsed/refractory MM patients was significantly higher than that in normal controls and patients reached plateau stage (p < 0.05), there was no statistically significant difference between newly diagnosed and relapsed/refractory MM patients (p > 0.05). The expression of BAFF and BCL-2 mRNA related with D-S staging and ß2-MG level. It is concluded that the expression levels of BAFF and BCL-2 mRNA increase, moreover the expression levels of BAFF and BCL-2 mRNA in newly diagnosed and relapsed/refractory MM patients are higher than those in patients reached plateau stage, which suggest the BAFF and BCL-2 may be involved in occurrence and development of MM; the relation of expression level of BAFF and BCL-2 mRNA to MM load is positive, which indicates the expression level of BAFF and BCL-2 mRNA may be a new indicator for evaluating the prognosis of MM patients.