DESIGN, SYNTHESIS AND BIOLOGICAL EVALUATION OF NOVEL CHALCONE ANALOGS AS POTENTIAL THERAPEUTIC AGENTS FOR CASTRATION RESISTANT PROSTATE CANCER

Abstract

Prostate cancer (PCa) is the second most frequently diagnosed malignancy, as well as a leading cause of cancer-related mortality in men globally. Despite the initial response to hormonal targeted therapy, the majority of patients ultimately progress to a lethal form of the disease, castration-resistant prostate cancer (CRPC), which currently lacks curative therapeutic options and is associated with poor prognosis. Therefore, the objective of this study was to discover and develop novel treatment modalities for CRPC. Chalcones, also known as 1,3-diphenyl-2-propen-1-ones, are among the highly attractive scaffolds being investigated for their antitumor activities. A library of 26 cyclic (tetralone-based) and acyclic chalcone analogs, in which ring B was either substituted with nitrogen mustard or replaced by pyrrole or pyridine heterocyclic rings, were designed, synthesized and evaluated as potential therapies for CRPC. The design was guided by in-silico ADMET prediction in which analogs with favorable drug-likeness properties were prioritized. The new compounds were synthesized by Claisen-Schmidt condensation reaction, purified and characterized by extensive structural elucidation studies. The compounds in vitro cytotoxicity was evaluated against two androgen receptor (AR)-negative prostate cancer cell lines (PC3 and DU145). Among the tested compounds, pyridine containing analogs (13, 15 and 16) showed potent antiproliferative activities at low micromolar levels with IC50 values ranging between 4.32-6.47 µM against PC3 and DU145 cell lines. Detailed biological studies of the lead molecule 16 revealed that it can significantly induce apoptosis through upregulation of Bax and downregulation of Bcl-2. In addition, compound 16 potently inhibited colony formation and reduced cell migration of AR-negative PCa cell lines (PC3 and DU145). The molecular pathway analysis showed that the anticancer activity of compound 16 is associated with blocking of ERK1/2 and Akt activities. Furthermore, compound 16 inhibited angiogenesis in the chick chorioallantoic membrane (CAM) model as compared to control. Structure-activity relationship study on pyridine-based chalcones revealed that the cytotoxicity could dramatically improve via changing the methoxylation pattern by more than 2-folds (IC50 << 2.5 μM). These results indicate that pyridine-based chalcones could serve as promising lead molecules for the treatment of CRPC; thus, further in vitro and in vivo studies are warranted.