Discovery of Novel Non-Steroidal Cytochrome P450 17A1 Inhibitors as Potential Prostate Cancer Agents

The current study presents the design, synthesis, and evaluation of novel cytochrome P450 17A1 (CYP17A1) ligands. CYP17A1 is a key enzyme in the steroidogenic pathway that produces androgens among other steroids, and it is implicated in prostate cancer. The obtained compounds are potent enzyme inhibitors (sub µM) with antiproliferative activity in prostate cancer cell lines. The binding mode of these compounds is also discussed.

Comparative study of the binding mode between cytochrome P450 17A1 and prostate cancer drugs in the absence of haem iron

According to the X-ray crystal structures of CYP17A1 (including its complexes with inhibitors), it is shown that a hydrogen bond exists between CYP17A1 and its inhibitors (such as abiraterone and TOK-001). Previous short MD simulations (50 ns) suggested that the binding of abiraterone to CYP17A1 is stronger than that of TOK-001. In this work, by carrying out long atomistic MD simulations (200 ns) of CYP17A1 and its complexes with abiraterone and TOK-001, we observed a binding mode between CYP17A1 and abiraterone, which is different from the binding mode between CYP17A1 and TOK-001. In the case of abiraterone binding, the unfilled volume in the active site cavity increases the freedom of movement of abiraterone within CYP17A1, leading to the collective motions of the helices G and B' as well as the breaking of hydrogen bond existing between the 3β-OH group of abiraterone and N202 of CYP17A1. However, the unfilled volume in the active site cavity can be occupied by the benzimidazole ring of TOK-001, restraining the motion of TOK-001. By pulling the two inhibitors (abiraterone and TOK-001) out of the binding pocket in CYP17A1, we discovered that abiraterone and TOK-001 were moved from their binding sites to the surface of protein similarly through the channels formed by the helices G and B'. In addition, based on the free energy calculations, one can see that it is energetically favorable for the two inhibitors (abiraterone and TOK-001) to enter into the binding pocket in CYP17A1.

Alterations in the steroid biosynthetic pathways in the human prefrontal cortex in mood disorders: A post-mortem study

Altered levels of steroids have been reported in the brain, cerebral spinal fluid and plasma of patients with mood disorders. Neuroimaging studies have reported both functional and structural alterations in mood disorders, for instance in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC). In order to determine whether the endogenous production of steroids is altered in the ACC and DLPFC of patients with major depressive disorder (MDD) or bipolar disorder (BPD), quantitative real-time PCR was performed to detect mRNA expression level of key enzymes in the steroid biosynthetic pathways. In MDD, a significant decrease in mRNA level of cytochrome P450 17A1 (CYP17A1, synthesizing C19 ketosteroids) in the ACC and a significant increase in mRNA levels of hydroxysteroid sulfotransferase 2A1 [SULT2A1, catalyzing the sulfate conjugation of dehydroepiandrosterone (DHEA)] were observed in the DLPFC, suggesting alterations in DHEA and its sulfate metabolite DHEAS levels. Decreased intensity and distribution of CYP17A1 immunohistochemical staining was found in the ACC of MDD patients. Interestingly, there was a significant positive correlation between the mRNA levels of CYP17A1 and tyrosine-related kinase B (TrkB) full length isoform. In a unique post-mortem human brain slice culture paradigm, BDNF mRNA expression was found to be significantly increased following incubation with DHEA. Together, these data indicate a close relationship between DHEA and BDNF-TrkB pathways in depression. Furthermore, in the DLPFC, higher mRNA levels of 11β-hydroxysteroid dehydrogenase-1 (HSD11B1, reducing cortisone to the active hormone cortisol) and steroidogenic acute regulatory protein (STAR, facilitating the shuttle of cholesterol through the intermembrane space) were found in the MDD patients and BPD patients, respectively. In conclusion, this study suggests the presence of a disturbance in the endogenous synthesis of DHEA and DHEAS in mood disorders, which has a close relationship with BDNF-TrkB signaling.

[Interaction of novel oxazoline derivatives of 17(20)e-pregna-5,17(20)-diene with cytochrome P450 17A1]

In order to find novel inhibitors of 17a-hydroxylase-17,20-lyase (cytochrome P450 17A1, CYP17A1), a key enzyme of biosynthesis of androgens, molecular docking of six new oxazoline-containing derivatives 17(20)E-pregna-5,17(20)-diene has been carried out to the active site of the crystal structure of CYP17A1 (pdb 3ruk). Results of this study indicate that: 1) complex formation of docked compounds with CYP17A1 causes their isomerization in energetically less favorable 17(20)Z-isomer; 2) the localization of the steroid moiety of all compounds in the active site is basically the same; 3) the structure of the oxazoline moiety significantly influences its position relative to heme as well as the energy of complex formation; 4) coordination of the nitrogen atom of the oxazoline moiety and the heme iron is only possible in the 17(20)Z-conformation with anti oriented double bonds 17(20), and C=N; 5) the presence of two substituents at C4' of the oxazoline moiety significantly impairs ligand binding; 6) oxazoline--and benzoxazole-containing derivatives 17(20)E-pregna-5,17(20)-diene can effectively inhibit the catalytic activity CYP17A1 and may be of interest as a basis for the development of new drugs for the treatment of androgen-dependent cancer.