Itraconazole (ITZ) is an FDA-approved member of the triazole class of anti-fungal agents. Two recent drug repurposing screens identified ITZ as a promising anti-cancer chemotherapeutic that inhibits both angiogenesis and the hedgehog (Hh) signaling pathway. We have synthesized and evaluated first and second generation ITZ analogues for their anti-Hh and anti-angiogenic activities to more fully probe the structural requirements for these anti-cancer properties. Our overall results suggest that the triazole functionality is required for ITZ-mediated inhibition of angiogenesis, but that it is not essential for inhibition of Hh signaling. The synthesis and evaluation of stereochemically defined des-triazole ITZ analogues also provides key information as to the optimal configuration around the dioxolane ring of the ITZ scaffold. Finally, the results from our studies suggest that two distinct cellular mechanisms of action govern the anti-cancer properties of the ITZ scaffold.

A family of optically active H(8)BINOL-AM compounds containing 3,3'-bis-tertiary amine substituents are synthesized by using a one-step reaction of H(8)BINOL with amino methanols that were in situ generated from various cyclic or acyclic secondary amines and paraformaldehyde. The H(8)BINOL-AM compounds are used to catalyze the reaction of functional arylzincs, in situ prepared from the reaction of aryliodides with ZnEt(2), with aldehydes to produce chiral diaryl carbinols and a few arylalkyl carbinols. Through this study, highly enantioselective catalysts were identified. It was found that the H(8)BINOL-AM compounds with sterically less congested cyclic or acyclic amino methyl substituents were more enantioselective than those with more bulky substituents. The pyrrolidinyl derivative (S)-12 in most cases showed greater enantioselectivity than other H(8)BINOL-AM compounds, especially for the challenging ortho-substituted aromatic aldehydes. A H(8)BINOL-AM with 3,3'-bis-sec-amine substituents, prepared by a multistep method, was also used to catalyze the arylzinc addition to aldehydes, but it showed enantioselectivity lower than that of the compounds with tertiary amine groups. It was found for the first time that an aryl bromide, 2-bromothiophene, could be used to prepare an arylzinc reagent by reaction with ZnEt(2). The addition of this heteroarylzinc reagent to an aldehyde in the presence of (S)-12 proceeded with good enantioselectivity.

Oxysterols (OHCs) are byproducts of cholesterol oxidation that are known to activate the Hedeghog (Hh) signaling pathway. While OHCs that incorporate hydroxyl groups throughout the scaffold are known, those that act as agonists of Hh signaling primarily contain a single hydroxyl on the alkyl side chain. We sought to further explore how side chain hydroxylation patterns affect oxysterol-mediated Hh activation, by performing a structure−activity relationship study on a series of synthetic OHCs. The most active analogue, 23(R)-OHC (35), demonstrated potent activation of Hh signaling in two Hh-dependent cell lines (EC 50 values 0.54−0.65 μM). In addition, OHC 35 was approximately 3-fold selective for the Hh pathway as compared to the liver X receptor, a nuclear receptor that is also activated by endogenous OHCs. Finally, 35 induced osteogenic differentiation and osteoblast formation in cultured cells, indicating functional agonism of the Hh pathway.

Previous structure−activity relationship studies for vitamin D3 (VD3) inhibition of Hedgehog (Hh) signaling directed the design, synthesis, and evaluation of a series of VD3-based analogues that contain an aromatic A-ring mimic. Characterization of these compounds in a series of cellular assays demonstrated their ability to potently and selectively downregulate Hh pathway signaling. The most active of these, 17, inhibited pathway signaling in Hh-dependent mouse fibroblasts (IC 50 = 0.74 ± 0.1 μM) and cultured cancer cells (IC 50 values 3.8 ± 0.1 to 5.2 ± 0.2 μM). In addition, 17 demonstrated reduced activation of the vitamin D receptor (VDR) compared to VD3 in these cellular models. These results suggest that VD3-based analogues with an aromatic A-ring are a valid scaffold for the development of more selective and potent Hh pathway inhibitors and identify 17 as an intriguing lead from this class of compounds for further development. In addition, our analysis of Hh pathway inhibitors in cancer cells suggests that the murine basal cell carcinoma cell line ASZ001 and the human medulloblastoma cell line DAOY are appropriate in vitro cancer models for early stage evaluation of pathway inhibition.

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