ABSTRACT
Objective·To establish a cell-based screening system for identification of compounds with activity in regulating retinoic acid receptor (RARα) stability. Methods·The modified pMSCV plasmid constructs, named as RARα-EGFP-IRES-DsRed, consists of enhanced green fluorescent protein (EGFP) fusing to RARα and red fluorescent protein (DsRed) as internal references incorporating the internal ribosome entry site (IRES) as interval sequence. The RARα-EGFP-IRES-DsRed plasmid was stably transfected into NB4 cells which were named as NB4-pMGIR-RARα. Fluorescence signals of EGFP and DsRed indirectly reflecting the expression of RARα, were detected by flow cytometry in cells that were treated with all-trans retinoic acid, sodium valproate, cytarabine, lenalidomide, etoposide, montelukast and gambogic acid, respectively. Effects of these compounds on the expression of RARα protein were further examined by Western blotting. Results·A double fluorescence reporter system for screening compounds that can increase the stability of RARα protein was successfully established, and sodium valproate was identified as a potent compound to promote the stability of RARα. Conclusion·The double fluorescence reporter system can be used to screen compounds regulating the stability of RARα protein, which can be further used to identify compounds regulating the stability of other proteins.
ABSTRACT
Objective·To explore the biologic effect and mechanism of adenanthin (Aden) on multiple myeloma (MM) cells. Methods·MM cells, H929 and U266 were treated with various dose of Aden for different time, and the density and viability of MM cells were detected by trypan blue exclusion assay. After H929 and U266 cells were treated with various dose of Aden for 24 hours, cell growth inhibition was examined by CCK8 assay, and cell apoptosis was examined by AnnexinV-APC/PI staining assay. Apoptosis related proteins, NF-κB signaling pathway associated proteins and the NF-κB regulated proteins were detected by Western blotting. The effect of Aden on the thermal stability of IKKβ protein was determined by CETSA assay. Results·Trypan blue exclusion results showed that Aden inhibited cell growth and reduced cell viability in concentration and time dependent manners. U266 was more sensitive than H929 when exposed to the same concentration of Aden. The CCK8 results showed that Aden inhibited the growth of H929 and U266 cells in a concentration dependent manner. Flow cytometry results suggested that Aden induced a low apoptosis rate of MM cells. Moreover, cleavage of caspase3 and PARP were detected in U266 cells but not in H929 cells. CETSA assay indicated that Aden decreased the thermal stability of IKKβ. Expression of p-p65 and p-IκBα proteins decreased in MM cells treated with Aden. Conclusion·Aden significantly inhibits MM cell proliferation by inhibiting NF-κB activation through interacting with IKKβ. Aden has little effect on apoptosis of MM cells.