Discovery of Novel Tankyrase Inhibitors through Molecular Docking-Based Virtual Screening and Molecular Dynamics Simulation Studies

Tankyrase enzymes (TNKS), a core part of the canonical Wnt pathway, are a promising target in the search for potential anti-cancer agents. Although several hundreds of the TNKS inhibitors are currently known, identification of their novel chemotypes attracts considerable interest. In this study, the molecular docking and machine learning-based virtual screening techniques combined with the physico-chemical and ADMET (absorption, distribution, metabolism, excretion, toxicity) profile prediction and molecular dynamics simulations were applied to a subset of the ZINC database containing about 1.7 M commercially available compounds. Out of seven candidate compounds biologically evaluated in vitro for their inhibition of the TNKS2 enzyme using immunochemical assay, two compounds have shown a decent level of inhibitory activity with the IC50 values of less than 10 nM and 10 μM. Relatively simple scores based on molecular docking or MM-PBSA (molecular mechanics, Poisson-Boltzmann, surface area) methods proved unsuitable for predicting the effect of structural modification or for accurate ranking of the compounds based on their binding energies. On the other hand, the molecular dynamics simulations and Free Energy Perturbation (FEP) calculations allowed us to further decipher the structure-activity relationships and retrospectively analyze the docking-based virtual screening performance. This approach can be applied at the subsequent lead optimization stages

Synthesis, Molecular Docking, In Vitro and In Vivo Studies of Novel Dimorpholinoquinazoline-Based Potential Inhibitors of PI3K/Akt/mTOR Pathway

A (series) range of potential dimorpholinoquinazoline-based inhibitors of the PI3K/Akt/mTOR cascade was synthesized. Several compounds exhibited cytotoxicity towards a panel of cancer cell lines in the low and sub-micromolar range. Compound 7c with the highest activity and moderate selectivity towards MCF7 cells which express the mutant type of PI3K was also tested for the ability to inhibit PI3K-(signaling pathway) downstream effectors and associated proteins. Compound 7c inhibited the phosphorylation of Akt, mTOR, and S6K at 125–250 nM. It also triggered PARP1 cleavage, ROS production, and cell death via several mechanisms. Inhibition of PI3Kα was observed at a concentration of 7b 50 µM and of 7c 500 µM and higher, that can indicate minority PI3Kα as a target among other kinases in the titled cascade for 7c. In vivo studies demonstrated an inhibition of tumor growth in the colorectal tumor model. According to the docking studies, the replacement of the triazine core in gedatolisib (8) by a quinazoline fragment, and incorporation of a (hetero)aromatic unit connected with the carbamide group via a flexible spacer, can result in more selective inhibition of the PI3Kα isoform

Human tankyrases are aberrantly expressed in colon tumors and contain multiple epitopes that induce humoral and cellular immune responses in cancer patients

PURPOSE: Tankyrases 1 and 2 are telomere-associated poly(ADP-ribose) polymerases (PARP) that can positively regulate telomere elongation and interact with multiple cellular proteins. Recent reports implicated tankyrases as tumor antigens and potential targets of anticancer treatment. We examined expression of tankyrases in colon tumors and immune response to these enzymes in patients with different types of cancer. METHODS: mRNA and protein expression was evaluated by quantitative real-time RT-PCR and Western blotting, respectively. Humoral immune response to recombinant tankyrases was investigated by modified enzyme-linked immunoassays. Cellular immune response was analysed by ELISPOT and (51)Cr release assays. RESULTS: We found that both mRNA and protein levels of tankyrase 2 (TNKL) are upregulated in colon tumors. In contrast, protein level of tankyrase 1 (TNKS) is downregulated, while mRNA level shows variable changes. More than a quarter of colon cancer patients develop humoral immune response to at least one of the two tankyrases. In this study we mapped common and unique B-cell epitopes located in different domains of the two proteins. Additionally, we present evidence for T-cell responses both to epitopes that are unique for TNKL and to those shared between TNKL and TNKS. CONCLUSION: Our study favors a biomarker usage of antibody response to tankyrases. Spontaneous CD8(+) T-cell responses to these enzymes are rare and further investigation is needed to evaluate tankyrases as potential targets for cancer immunotherapy