ABSTRACT
Objective To investigate the effect of the ubiquitin-proteasome pathway inhibitor MG132 on the natural resistance to cisplatin in the human cervical cancer line (HCE1) muhicellular spheroid (HCE1/MCS) model and to probe it if MG132 could reverse the HCE1/MCS resistance to cisplatin, as well as the possible mechanism of drug resistance.Methods (1) HCE1/MCS was obtained using liquid overlay and rotating technique.(2)Four groups were established (MG132 group, cisplatin group, MG132 + cisplatin group, the control group).Cell viability were measured by trypan blue exclusion assay.Cell cycle and apoptosis were detected by flow cytometry.(3) The expression of nuclear factor (NF) kB of both HCE1 monolayer cells (HCEI/MC) and HCE1/MCS was detected by western blot, and the expression of B cell lymphoma/leukemia-2 (bcl-2) was detected by immunohistochemistry.Results (1) HCE1/MCS was established successfully.(2) Cell inhibited rate of HCE1/MC and HCE1/MCS was: in MG132 group, (11.67 ± 2.34) % vs (10.78 ± 1.17) % (P > 0.05) ; in MG132 + cisplatin group, (92.67 ± 2.52)% vs (91.33 ±2.18)% (P>0.05); in cisplatin group, (45.01±7.44)% vs (9.45±5.98)% (P<0.05).(3)The rate of apoptosis of HCE1/MC and HCE1/MCS were: in MG132 group, 8.14% and 5.97% ; in MG132 + cisplatin group, 99.01% and 95.22% ; in cisplatin group, 33.61% and 0.88%.(4)The expression level of NF-kB and the high expression rate of bcl-2 were: in HCE1/MCS of control group, 0.67 and 60% ; in HCE1/MCS of cisplatin group, 0.85 and 83% ; in HCE1/MCS of MG132 group, 0.39 and 20% ; in HCE1/MCS of MG132 + cisplatin group, 0.47 and 33%.Conclusions (1) HCE1/ MCS present natural resistance to cisplatin and may become a good model for the study of cervical cancer drug resistance in vitro.(2) MG132 could induce the inhibition and apoptosis of HCE1/MCS cells and partially reverse the natural resistance of HCE1/MCS to cisplatin, of which partially reverse the natural resistance may be in relation to the down-regulation of NF-kB and bcl-2 expression.
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AIM: To investigate the ability of leupeptin, TLCK and lactoferrin on tryptase release from human colon mast cells. METHODS: Human mast cells were dispersed from colon tissue with collagenase and hyaluronidase, and were challenged with stimulus for 15 min at 37 ℃. Tryptase concentrations were measured with a sandwich ELISA procedure. RESULTS: Leupeptin, TLCK and lactoferrin were not able to provoke significant tryptase release from human colon mast cells. But they were able to inhibit anti-IgE and calcium ionophore (CI)-induced tryptase release in a concentration-dependent manner. Preincubation of inhibitors of leupeptin and TLCK with cells for 20 min before challenging with anti-IgE failed to enhance their inhibitory actions. The extent of inhibition by leupeptin was increased when colon mast cells were preincubated for 20 min before CI being added. However, the same treatment failed to improve the action of TLCK. CONCLUSION: We found for the first time that leupeptin, TLCK and lactoferrin were able to inhibit anti-IgE and calcium ionophore-induced tryptase release from human colon mast cells, which may indicate a potential of a novel therapy for the treatment of inflammatory bowel disease or other mast cells-related diseases.
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Objective To study the PINK1 aggresome formation and it's features in response to proteasomal inhibition.Methods Full-length PINK1 cDNA were amplified by polymerase chain reaction (PCR)from fetus brain cDNA library and subcloned into the EcoR I and BamH I sites of the vector pEGFP- N1.The integrity of the constructs was confirmed by sequencing.COS-7 cells were transiently transfected with PINK1-pEGFP-N1 using Lipofectamine 2000.Cells were treated by MG-132 in order to test the effect of proteasome inhibition on aggregation formation.The protein level of wild-type PINK1 with or without MG-132 treatment was confirmed by Western blot analysis.The formation of PINK1 aggregates was tested by fluorescence and the presence of ubiquitin,and ?-synuclein in PINK1 aggregates was examined by immunofluorescence and confocal microscopy.Results The expression level of PINK1 was significant increased into the form of aggregate in cells treated with MG-132;immunostaining for endogenous ubiquitin and ?-synuclein revealed a co-localization of both proteins in PINK1-positive aggregates.Conclusions In the presence of MG-132,overexpressed PINK1 forms into aggregates,whose components are ubiquitin and ?-synuclein.