ABSTRACT
Heat shock protein 90 (Hsp90) is treated as a molecular therapeutic target for the prevention and treatment of cancer. Geldanamycin (GA) was the first identified natural Hsp90 inhibitor, but hepatotoxicity has limited its clinical application. Nevertheless, a new GA analog (WK-88- 1) with the non-benzoquinone skeleton, obtained from genetically engineered Streptomyces hygroscopicus, was found to have anticancer activity against two human breast cancer cell lines. WK-88-1 produced concentration-dependent inhibition of cell proliferation, cell cycle arrest, and apoptosis in estrogen receptor (ER)-positive MCF-7 and ER-negative MDA-MB-231 cell lines. Detailed analysis showed that WK-88-1 downregulated some key cell cycle molecules (CDK1 and cyclin B1) and lead to G2/M cell cycle arrest. Further studies also showed that WK-88-1 could induce human breast cancer cell apoptosis by downregulating Hsp90 client proteins (Akt, p-Akt, IKK, c-Raf, and Bcl-2), decreasing the ATP level, increasing reactive oxygen species production, and lowering the mitochondrial membrane potential. Meanwhile, we discovered that WK-88-1 significantly decreased the levels of Her-2 and ER-α in MCF-7 cells but not in MDA-MB-231 cells. In addition, WK-88-1 significantly increased caspase-3, -8, and -9 activities and the cleavage of PARP in a concentration-dependent manner (with the exception of caspase-3 and PARP in MCF-7 cells). Taken together, our preliminary results suggest that WK-88-1 has the potential to play a role in breast cancer therapy.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Benzoquinones/pharmacology , Breast Neoplasms/drug therapy , Cell Line, Tumor/drug effects , Lactams, Macrocyclic/pharmacology , Adenosine Triphosphate/analysis , Adenosine Triphosphate/metabolism , Antineoplastic Agents/metabolism , Benzoquinones/chemistry , Benzoquinones/metabolism , CDC2 Protein Kinase/metabolism , Caspase 3/metabolism , Caspase 8/metabolism , Caspase 9/metabolism , Cell Cycle Checkpoints/drug effects , Cell Proliferation/drug effects , Cyclin B1/metabolism , Down-Regulation , Estrogen Receptor alpha , Female , G2 Phase Cell Cycle Checkpoints/drug effects , HSP90 Heat-Shock Proteins/drug effects , Humans , Lactams, Macrocyclic/chemistry , Lactams, Macrocyclic/metabolism , M Phase Cell Cycle Checkpoints/drug effects , MCF-7 Cells/drug effects , Membrane Proteins , Mitochondrial Membranes , Reactive Oxygen Species/metabolism , Receptor, ErbB-2 , Receptors, Estrogen/drug effects , Streptomyces/metabolismABSTRACT
Corylifol A, a member of the isoflavone subclass of isoflavonoids, has long been considered to have various biological activities. Here, we sought to synthesize corylifol A glucosides by the in vitro glucosylation reaction using the UDP-glycosyltransferase YjiC from Bacillus licheniformis DSM 13, and obtained two novel glucosides: corylifol A-4',7-di-O-beta-d-glucopyranoside (1) and corylifol A-4'-O-beta-d-glucopyranoside (2). To improve the yield of the products, the reaction time, concentration of UDP-glucose, and pH of the buffer were optimized. The Michaelis constant (Km) was calculated to be 2.88 mM, and the maximal velocity (Vmax) was calculated to be 77.32 nmol/min/mg for UDP-glycosyltransferase. Meanwhile, the water-solubility of compounds 1 and 2 was approximately 27.03 and 15.13 times higher, respectively, than that of their parent compound corylifol A. Additionally, the corylifol A glycosylated products exhibited the highest stability at pH 9.6 and better temperature stability than corylifol A at 40, 60, 80 and 100 °C. In addition, cytotoxicity activity assays against three human tumor cell lines, only corylifol A showed moderate anti-proliferative activity. Overall, this work demonstrates that glycosylation can enhance the water solubility and stability of promising compounds, with potential for further development and application.
Subject(s)
Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacology , Flavones/chemical synthesis , Flavones/pharmacology , Glucosides/chemistry , Glycosyltransferases/metabolism , Antineoplastic Agents/chemistry , Bacillus licheniformis/enzymology , Cell Line, Tumor , Chemistry Techniques, Synthetic , Flavones/chemistry , Humans , Hydrogen-Ion Concentration , Solubility , Temperature , Water/chemistryABSTRACT
OBJECTIVE: To modify the structure of psoralidin using in vitro enzymatic glycosylation to improve its water solubility and stability. METHODS: A new psoralidin glucoside (1) was obtained by enzymatic glycosylation using a UDP- glycosyltransferase. The chemical structure of compound 1 was elucidated by HR-ESI-MS and nuclear magnetic resonance (NMR) analysis. The high-performance liquid chromatography (HPLC) peaks were integrated and sample solution concentrations were calculated. MTT assay was used to detect the cytotoxicity of the compounds against 3 cancer cell lines in vitro. Results Based on the spectroscopic data, the new psoralidin glucoside was identified as psoralidin-6',7-di-O-ß-D- glucopyranoside (1), whose water solubility was 32.6-fold higher than that of the substrate. Analyses of pH and temperature stability demonstrated that compound 1 was more stable than psoralidin at pH 8.8 and at high temperatures. Only psoralidin exhibited a moderate cytotoxicity against 3 human cancer cell lines. Conclusion In vitro enzymatic glycosylation is a powerful approach for structural modification and improving water solubility and stability of compounds.