lignans and rofecoxib

Encouraged by the anti-inflammatory activity of hinokinin in vivo, which is also observed for the analogues dinitrohinokinin and diidrocubebin, herein we used in vitro and in silico methods to assess their selectivity profiles and predict their binding modes with Cyclooxygenases (COX-1 and 2). The in vitro assays demonstrated dinitrohinokinin is about 13 times more selective for COX-2 than for COX-1, a similar profile observed for the drugs celecoxib (selective index ≈9) and meloxicam (selective index ≈11). Predictions of the binding modes suggested dinitrohinokinin interacts with COX-2 very similarly to rofecoxib, exploring residues at the hydrophilic pocket of the enzyme that accessible to ligands only in this isoform. This lignan also interacts with COX-1 in a similar mode to meloxicam, blocking the access of the substrate to the catalytic cleft. Therefore, dinitrohinokinin is a promising lead for the design of selective COX-2 inhibitors.

Topics: 4-Butyrolactone; Benzodioxoles; Binding Sites; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase Inhibitors; Humans; Lactones; Lignans; Meloxicam; Molecular Docking Simulation; Protein Binding; Quantitative Structure-Activity Relationship; Substrate Specificity; Sulfones

Cytochrome P450c17 (CYP17) has been linked to various hormone-related diseases, including breast cancer, thus being a potential target for cancer chemoprevention. We studied the naturally occurring phytochemical enterolactone (ENL) and 13 VIOXX-related lactone derivatives (CRI-1 to CRI-13) for their effects on CYP17 activity and expression and on cell cycle status in the human H295R adrenocorticocarcinoma cell line. Of the tested compounds, only CRI-3, -7, -10 and -12 showed to be inhibitors of CYP17 activity in H295R cells. This inhibition was not due to decreased mRNA expression, but was apparently caused by post-translational modification of the CYP17 enzyme. The MAPK kinase (MEK) inhibitor PD98059 induced CYP17 activity by 24%, while co-incubation of the CRI-s with PD98059, reduced CYP17 activity even further than the reduction caused by the CRI-s alone. In addition, CRI-3, -7, -10 and -12 arrested the cell cycle in the G(2)/M phase. The structure-activity similarities of the CRI-s with known micro-tubule binding agents strongly suggest that cell cycle arrest is a result of interaction with tubulin. We conclude that the proposed cancer chemopreventive actions of ENL are not mediated through interaction with CYP17 or cell cycle status. Of the VIOXX-related lactone derivatives, CRI-7 could prove useful in the prevention of hormone-dependent cancers, such as breast cancer, since in vitro it shows low cytotoxicity, it is a potent inhibitor of CYP17 activity and strong inducer of cell cycle arrest.

Topics: 4-Butyrolactone; Adrenal Cortex Neoplasms; Adrenocortical Carcinoma; Cell Cycle; Cell Line, Tumor; Enzyme Induction; Flavonoids; Gene Expression; Humans; Lactones; Lignans; Mitogen-Activated Protein Kinase Kinases; Neoplasms, Hormone-Dependent; Phytoestrogens; Protein Processing, Post-Translational; Steroid 17-alpha-Hydroxylase; Structure-Activity Relationship; Sulfones