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Effects of triptolide on RIZ1 expression, proliferation, and apoptosis in multiple myeloma U266 cells
Fei Zhao1, Yan Chen, Ling-lan Zeng
1Department of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Aim:
To investigate the effects of triptolide on proliferation and apoptosis as well as on the expression of RIZ1 in the human multiple myeloma cell line U266 in vitro.
Methods:
The effect of triptolide on the growth of U266 cells was studied by MTT assay. Apoptosis was detected by Hoechst 33258 staining and Annexin V/PI double-labeled flow cytometry, and caspase-3 mRNA was measured by RT-PCR. Western blotting, flow cytometry and RT-PCR were used to assess the expression of RIZ1, and the location and expression of H3K9me1 were detected by confocal microscopy and Western blotting.
Results:
Triptolide significantly inhibited the proliferation of U266 cells in a time- and concentration-dependent manner (the IC(50) value for a 24-h exposure was 157.19+/-0.38 nmol/L). Triptolide induced typical apoptotic morphological changes. Triptolide 40, 80, and 160 nmol/L treatment induced significant caspase-3-dependent apoptosis compared with control group (10.5%+/-1.23%, 37.9%+/-2.45%, and 40.5%+/-2.30% vs 3.8%+/-1.98%, P<0.05). Compared with peripheral blood monocular cells (PBMC) from healthy donors, the protein expression of RIZ1 in U266 cells was relatively low, but the mRNA and protein expression of RIZ1 were strikingly increased by triptolide in a concentration-dependent manner. Triptolide increased the protein expression of RIZ1 and RIZ1 methylates histone H3 lysine 9 in U266 cells.
Conclusion:
Triptolide increased the protein expression of RIZ1, inhibited the proliferation, and induced caspase-dependent apoptosis in U266 cells.
Insights
Triptolide inhibits multiple myeloma cell growth and triggers apoptosis by increasing RIZ1 expression. This study highlights triptolide
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Multiple myeloma is a hematological malignancy characterized by uncontrolled proliferation of plasma cells.
- RIZ1 (Retinoblastoma-interacting zinc finger protein 1) plays a role in tumor suppression and cell differentiation.
- Triptolide, a compound from Tripterygium wilfordii, exhibits anti-cancer properties.
Purpose of the Study:
- To investigate the in vitro effects of triptolide on U266 human multiple myeloma cells.
- To assess triptolide's impact on cell proliferation, apoptosis, and RIZ1 expression.
Main Methods:
- Cell proliferation was evaluated using MTT assays.
- Apoptosis was detected via Hoechst staining and Annexin V/PI flow cytometry.
- RIZ1 expression and H3K9me1 methylation were analyzed by RT-PCR, Western blotting, and confocal microscopy.
Main Results:
- Triptolide significantly inhibited U266 cell proliferation in a dose- and time-dependent manner (IC50 = 157.19 nmol/L at 24h).
- Triptolide induced significant caspase-3-dependent apoptosis in U266 cells.
- Triptolide treatment increased both mRNA and protein levels of RIZ1, and enhanced H3K9me1 methylation in U266 cells.
Conclusions:
- Triptolide demonstrates potent anti-proliferative and pro-apoptotic effects on U266 multiple myeloma cells.
- The observed effects are associated with increased RIZ1 expression and histone methylation.
- Triptolide holds potential as a therapeutic agent for multiple myeloma.
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