Anticancer activity of VDR-coregulator inhibitor PS121912

Drug repositioning in thyroid cancer: from point mutations to gene fusions

The diagnosis of thyroid cancer (TC) has increased dramatically in recent years. Papillary TC is the most frequent type and has shown a good prognosis. Conventional treatments for TC are surgery, hormonal therapy, radioactive iodine, chemotherapy, and targeted therapy. However, resistance to treatments is well documented in almost 20% of all cases. Genomic sequencing has provided valuable information to help identify variants that hinder the success of chemotherapy as well as to determine which of those represent potentially druggable targets. There is a plethora of targeted therapies for cancer, most of them directed toward point mutations; however, chromosomal rearrangements that generate fusion genes are becoming relevant in cancer but have been less explored in TC. Therefore, it is relevant to identify new potential inhibitors for genes that are recurrent in the formation of gene fusions. In this review, we focus on describing potentially druggable variants and propose both point variants and fusion genes as targets for drug repositioning in TC.

Vitamin D in Triple-Negative and BRCA1-Deficient Breast Cancer-Implications for Pathogenesis and Therapy

Several studies show that triple-negative breast cancer (TNBC) patients have the lowest vitamin D concentration among all breast cancer types, suggesting that this vitamin may induce a protective effect against TNBC. This effect of the active metabolite of vitamin D, 1α,25-dihydroxyvitamin D3 (1,25(OH)2D), can be attributed to its potential to modulate proliferation, differentiation, apoptosis, inflammation, angiogenesis, invasion and metastasis and is supported by many in vitro and animal studies, but its exact mechanism is poorly known. In a fraction of TNBCs that harbor mutations that cause the loss of function of the DNA repair-associated breast cancer type 1 susceptibility (BRCA1) gene, 1,25(OH)2D may induce protective effects by activating its receptor and inactivating cathepsin L-mediated degradation of tumor protein P53 binding protein 1 (TP53BP1), preventing deficiency in DNA double-strand break repair and contributing to genome stability. Similar effects can be induced by the interaction of 1,25(OH)2D with proteins of the growth arrest and DNA damage-inducible 45 (GADD45) family. Further studies on TNBC cell lines with exact molecular characteristics and clinical trials with well-defined cases are needed to determine the mechanism of action of vitamin D in TNBC to assess its preventive and therapeutic potential.

Alternative binding sites at the vitamin D receptor and their ligands

In recent decades, the majority of ligands developed for the vitamin D receptor (VDR) bind at its deeply buried genomic ligand binding pocket. Theses ligands can be categorized into agonists and partial agonists/antagonists. A limited number of ligands, most of them peptides, bind the VDR‒coactivator binding site that is formed in the presence of an agonist and inhibit coactivator recruitment, and therefore transcription. Another solvent exposed VDR‒ligand binding pocket was identified for lithocholic acid, improving the overall stability of the VDR complex. Additional proposed interactions with VDR are discussed herein that include the alternative VDR‒ligand binding pocket that may mediate both non-genomic cellular responses and binding function 3 that was identified for the androgen receptor. Many VDR ligands increase blood calcium levels at therapeutic concentrations in vivo, thus the identification of alternative VDR‒ligand binding pockets might be crucial to develop non-calcemic and potent ligands for VDR to treat cancer and inflammatory disease.

Effects of 1,25 and 24,25 Vitamin D on Corneal Epithelial Proliferation, Migration and Vitamin D Metabolizing and Catabolizing Enzymes

This study investigated the effects of 1,25(OH)₂D3 and 24R,25(OH)₂D3 on corneal epithelial cell proliferation, migration, and on the vitamin D activating enzyme CYP27B1 (produces 1,25(OH)₂D3) and inactivating enzyme CYP24A1 (produces 24R,25(OH)₂D3). The role of the vitamin D receptor (VDR) was also examined. In VDR wildtype mouse corneal epithelial cells (WT), 1,25(OH)₂D3 increased CYP24A1 protein expression and decreased CYP27B1 expression. In VDR knockout mouse epithelial cells (KO), 1,25(OH)₂D3 increased CYP24A1 and CYP27B1 protein expression. 1,25(OH)₂D3 did not affect WT cell proliferation, but did stimulate VDR KO cell proliferation. In a human corneal epithelial cell line (HCEC), 1,25(OH)₂D3 increased CYP24A1 mRNA and protein expression. 1,25(OH)₂D3 increased CYP27B1 mRNA levels in HCEC, but had no effect on CYP27B1 protein levels. 1,25(OH)₂D3 inhibited HCEC proliferation and stimulated cell migration in primary human epithelial cells. 24,25(OH)₂D3, on the other hand, increased both CYP24A1 and CYP27B1 protein expression in WT and VDR KO cells, and stimulated cell proliferation in both WT and KO cells. In HCEC, 24,25(OH)₂D3 increased CYP24A1 and CYP27B1 mRNA and protein expression, and stimulated cell migration. In human primary corneal epithelial cells, 24,25(OH)₂D3 stimulated migration. We conclude that 24R,25(OH)₂D3 is likely involved in corneal epithelial cell regulation independent of 1,25(OH)₂D3 or VDR.

Chiral Brønsted Acid Catalyzed Enantioselective aza-Friedel-Crafts Reaction of Cyclic α-Diaryl N-Acyl Imines with Indoles

Asymmetric addition of indoles to cyclic α-diaryl-substituted N-acyl imines, which are generated in situ from 3-aryl 3-hydroxyisoindolinones, is described. The transformation proceeds smoothly with a broad range of indoles and isoindolinone alcohols using a SPINOL-derived chiral Brønsted acid catalyst to afford α-tetrasubstituted (3-indolyl)(diaryl)methanamines in excellent yields and enantioselectivities (up to 98% yield, up to >99:1 e.r.). The origin of stereochemical induction is supported by DFT calculations and experimental data.

Brønsted Acid Catalyzed Oxygenative Bimolecular Friedel-Crafts-type Coupling of Ynamides

A non-metal approach for accessing α-oxo carbene surrogates for a C-C bond-forming bimolecular coupling between ynamides and nucleophilic arenes was developed. This acid-catalyzed coupling features mild temperature, which is critical for the required temporal chemoselectivity among nucleophiles. The scope of nucleophiles includes indoles, pyrroles, anilines, phenols and silyl enolethers. Furthermore, a direct test of S_N 2' mechanism has been provided by employing chiral N,N'-dioxides which also enlightens the nature of the intermediates in related metal-catalyzed processes.

Inhibitors for the Vitamin D Receptor-Coregulator Interaction

The vitamin D receptor (VDR) belongs to the superfamily of nuclear receptors and is activated by the endogenous ligand 1,25-dihydroxyvitamin D3. The genomic effects mediated by VDR consist of the activation and repression of gene transcription, which includes the formation of multiprotein complexes with coregulator proteins. Coregulators bind many nuclear receptors and can be categorized according to their role as coactivators (gene activation) or corepressors (gene repression). Herein, different approaches to develop compounds that modulate the interaction between VDR and coregulators are summarized. This includes coregulator peptides that were identified by creating phage display libraries. Subsequent modification of these peptides including the introduction of a tether or nonhydrolyzable bonds resulted in the first direct VDR-coregulator inhibitors. Later, small molecules that inhibit VDR-coregulator inhibitors were identified using rational drug design and high-throughput screening. Early on, allosteric inhibition of VDR-coregulator interactions was achieved with VDR antagonists that change the conformation of VDR and modulate the interactions with coregulators. A detailed discussion of their dual agonist/antagonist effects is given as well as a summary of their biological effects in cell-based assays and in vivo studies.

Antitumor Activity of 3-Indolylmethanamines 31B and PS121912

AIM

To investigate the in vivo effects of 3-indolylmethanamines 31B and PS121912 in treating ovarian cancer and leukemia, respectively.

MATERIALS AND METHODS

Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and western blotting were applied to demonstrate the induction of apoptosis. Xenografted mice were investigated to show the antitumor effects of 3-indolylmethanamines. (13)C-Nuclear magnetic resource (NMR) and western blotting were used to demonstrate inhibition of glucose metabolism.

RESULTS

31B inhibited ovarian cancer cell proliferation and activated caspase-3, cleaved poly (ADP-ribose) polymerase 1 (PARP1), and phosphorylated mitogen-activated protein kinases (MAPK), JUN N-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38. 31B reduced ovarian cancer xenograft tumor growth and PS121912 inhibited the growth of HL-60-derived xenografts without any sign of toxicity. Compound 31B inhibited de novo glycolysis and lipogenesis mediated by the reduction of fatty acid synthase and lactate dehydrogenase-A expression.

CONCLUSION

3-Indolylmethanamines represent a new class of antitumor agents. We have shown for the first time the in vivo anticancer effects of 3-indolylmethanamines 31B and PS121912.