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[ ABSTRACT] AIM:To observe the influences of different concentrations of MG132 on apoptosis and beta-amyloid protein ( Aβ) generation in SH-SY5Y cells, and to explore the underlying mechanism.METHODS:SHSY-5Y cells were incubated with MG132 for 24 h.The final concentrations of MG132 were 2.5, 5 and 10μmol/L.The cell viability was de-termined by MTT assay.The cell apoptosis was assessed by flow cytometry.The levels of Aβwere measured by ELISA. The relative protein levels were detected by Western blot.RESULTS:In the SH-SY5Y cells, MG132 reduced the cell via-bility, induced the cell apoptosis, increased the level of Aβ, and increased the expression of the related proteins for Aβgeneration in a concentration-dependent manner.CONCLUSION: MG132 induces apoptosis and increases the levels of Aβ1-42 and Aβ1-40 by regulating the proteins related to Aβgeneration in the SH-SY5Y cells.
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OBJECTIVE To examine the reversal effect of desipramine (DMI) on resistance to temozolomide(TMZ) in U251/TR cells and explore its mechanism. METHODS U251/TR cells were exposed to DMI (20-80μmol · L-1) or TMZ (0.5-10 mmol · L-1) for 24 h, cell viability was determined by cell counting kit-8 assay with IC50 calculated. The cytotoxicity of U251/TR cells treated with TMZ (1 or 2 mmol·L-1) in combination with DMI (20, 30 or 40 μmol · L-1) for 24 h was detected using CCK-8 assay. Synergism between DMI and TMZ was analyzed by the JIN Zheng-jun method. Apoptosis of U251/TR cells induced by TMZ 1 mmol · L-1, DMI 30 μmol · L-1,or their combination was examined by Hoechst33258 stains and caspase 3 activity was detected by luminescence analysis. Expression of C/EBP homologous protein (CHOP) was measured using quantitative real-time PCR and Western blotting. The survival rate of U251/TR cells treated with TMZ 1 mmol·L-1 and/or DMI 30μmol·L-1 was also assessed after silencing CHOP expression by small interference RNA (siRNA). RESULTS DMI or TMZ alone inhibited the growth of U251/TR cells significantly in a concentration-dependent manner (r 2=0.983,0.982,P1.15), ie, compared with TMZ alone, TMZ (1 mmol·L-1) com?bined with DMI (30 μmol · L-1) produced significant nuclear fragmentation and condensation (P< 0.05). In addition, DMI and TMZ in combination activated caspase 3 activity in U251/TR cells (P<0.05). Knock?down of CHOP by specific siRNA attenuated the synergistic effect of DMI in the presence of TMZ, the survival rate of the combined drug group raised from 51.8%to 62.2%(P<0.05). CONCLUSION The results suggest that DMI reverse resistance of U251/TR cells to TMZ through activation of the CHOP-depend?ently apoptosis pathway.