Human cytochrome P450 17A1 structures with metabolites of prostate cancer drug abiraterone reveal substrate-binding plasticity and a second binding site.

Abiraterone acetate is a first-line therapy for castration-resistant prostate cancer. This prodrug is deacetylated in vivo to abiraterone, which is a potent and specific inhibitor of cytochrome P450 17A1 (CYP17A1). CYP17A1 performs two sequential steps that are required for the biosynthesis of androgens that drive prostate cancer proliferation, analogous to estrogens in breast cancer.

Discovery of EEDi-5273 as an Exceptionally Potent and Orally Efficacious EED Inhibitor Capable of Achieving Complete and Persistent Tumor Regression.

Embryonic ectoderm development (EED) is a promising therapeutic target for human cancers and other diseases. We report herein the discovery of exceptionally potent and efficacious EED inhibitors. By conformational restriction of a previously reported EED inhibitor, we obtained a potent lead compound.

EEDi-5285: An Exceptionally Potent, Efficacious, and Orally Active Small-Molecule Inhibitor of Embryonic Ectoderm Development.

Inhibition of embryonic ectoderm development (EED) is a new cancer therapeutic strategy. Herein, we report our discovery of EEDi-5285 as an exceptionally potent, efficacious, and orally active EED inhibitor. EEDi-5285 binds to the EED protein with an IC value of 0.

Discovery of Potent Small-Molecule Inhibitors of MLL Methyltransferase.

The mixed-lineage leukemia (MLL) protein, also known as MLL1, is a lysine methyltransferase specifically responsible for methylation of histone 3 lysine 4. MLL has been pursued as an attractive therapeutic target for the treatment of acute leukemia carrying the MLL fusion gene or MLL leukemia. Herein, we report the design, synthesis, and evaluation of an -adenosylmethionine-based focused chemical library which led to the discovery of potent small-molecule inhibitors directly targeting the MLL SET domain.

Structure-Based Design of N-(5-Phenylthiazol-2-yl)acrylamides as Novel and Potent Glutathione S-Transferase Omega 1 Inhibitors.

Using reported glutathione S-transferase omega 1 (GSTO1-1) cocrystal structures, we designed and synthesized acrylamide-containing compounds that covalently bind to Cys32 on the catalytic site. Starting from a thiazole derivative 10 (GSTO1-1 IC = 0.6 μM), compound 18 was synthesized and cocrystallized with GSTO1.

Design, Synthesis, and Biological Evaluation of 4-Quinoline Carboxylic Acids as Inhibitors of Dihydroorotate Dehydrogenase.

We pursued a structure-guided approach toward the development of improved dihydroorotate dehydrogenase (DHODH) inhibitors with the goal of forming new interactions between DHODH and the brequinar class of inhibitors. Two potential residues, T63 and Y356, suitable for novel H-bonding interactions, were identified in the brequinar-binding pocket. Analogues were designed to maintain the essential pharmacophore and form new electrostatic interactions through strategically positioned H-bond accepting groups.

Structural and Functional Evaluation of Clinically Relevant Inhibitors of Steroidogenic Cytochrome P450 17A1.

Human steroidogenic cytochrome P450 17A1 (CYP17A1) is a bifunctional enzyme that performs both hydroxylation and lyase reactions, with the latter required to generate androgens that fuel prostate cancer proliferation. The steroid abiraterone, the active form of the only CYP17A1 inhibitor approved by the Food and Drug Administration, binds the catalytic heme iron, nonselectively impeding both reactions and ultimately causing undesirable corticosteroid imbalance. Some nonsteroidal inhibitors reportedly inhibit the lyase reaction more than the preceding hydroxylase reaction, which would be clinically advantageous, but the mechanism is not understood.

An engineered transforming growth factor β (TGF-β) monomer that functions as a dominant negative to block TGF-β signaling.

The transforming growth factor β isoforms, TGF-β1, -β2, and -β3, are small secreted homodimeric signaling proteins with essential roles in regulating the adaptive immune system and maintaining the extracellular matrix. However, dysregulation of the TGF-β pathway is responsible for promoting the progression of several human diseases, including cancer and fibrosis. Despite the known importance of TGF-βs in promoting disease progression, no inhibitors have been approved for use in humans.

Structural insights into the function of steroidogenic cytochrome P450 17A1.

Cytochrome P450 17A1 (CYP17A1) operates at the core of human steroidogenesis, directing precursors into mineralocorticoids, glucocorticoids, or sex steroids. Although the 17α-hydroxylase and 17,20-lyase activities of this dual function enzyme have been investigated extensively, until recently no CYP17A1 structures were available to inform our understanding. Structures of CYP17A1 with a range of steroidal inhibitors and substrates are now available.

Promising Tools in Prostate Cancer Research: Selective Non-Steroidal Cytochrome P450 17A1 Inhibitors.

Cytochrome P450 17A1 (CYP17A1) is an important target in the treatment of prostate cancer because it produces androgens required for tumour growth. The FDA has approved only one CYP17A1 inhibitor, abiraterone, which contains a steroidal scaffold similar to the endogenous CYP17A1 substrates. Abiraterone is structurally similar to the substrates of other cytochrome P450 enzymes involved in steroidogenesis, and interference can pose a liability in terms of side effects.

Structures of human steroidogenic cytochrome P450 17A1 with substrates.

The human cytochrome P450 17A1 (CYP17A1) enzyme operates at a key juncture of human steroidogenesis, controlling the levels of mineralocorticoids influencing blood pressure, glucocorticoids involved in immune and stress responses, and androgens and estrogens involved in development and homeostasis of reproductive tissues. Understanding CYP17A1 multifunctional biochemistry is thus integral to treating prostate and breast cancer, subfertility, blood pressure, and other diseases. CYP17A1 structures with all four physiologically relevant steroid substrates suggest answers to four fundamental aspects of CYP17A1 function.

Acylphloroglucinol and xanthones from Hypericum ellipticum.

An acylphloroglucinol, elliptophenone A, and two xanthones, elliptoxanthone A and elliptoxanthone B, were isolated from the aerial portions of Hypericum ellipticum together with three known xanthones, 1,3,7-trihydroxy-8-(3-methyl-2-butenyl)-9H-xanthen-9-one, 1,6-dihydroxy-4-methoxy-9H-xanthen-9-one, and 1,4,5-trihydroxy-9H-xanthen-9-one. Their structures were determined by spectroscopic analyses. The acylphloroglucinol and xanthones were evaluated for cytotoxicity using three human colon cancer cell lines cell lines (HT-29, HCT-116 and Caco-2) and a normal human colon cell line (CCD-18Co).

New benzophenone O-glucoside from Hypericum ellipticum.

Examination of the acetone extract of the aerial parts of Hypericum ellipticum afforded a new acetylated benzophenone glucoside (3'-O-beta-D-3",4",6"-triacetylglucopyranosyl-2,4,5',6-tetrahydroxybenzophenone) together with catechin and epicatechin. The structure of the benzophenone glucoside was determined by 2D NMR spectroscopic data. The compound inhibited the proliferation of CNS tumor cell line (SF-268) and lipid peroxidation in in vitro assays.