ABSTRACT
The Ca2+/calmodulin-mediated phosphatase activity of calcineurin (CN) integrates calcium-mediated signaling with gene expression programs involved in the control of essential cellular processes in health and disease, such as the immune response and the pathogenesis of cancer progression and metastasis. In addition, CN is the target of the immunosuppressive drugs cyclosporine A (CsA) and FK-506 which are the cornerstone of immunosuppressant therapy. Unfortunately, long-term administration of these drugs results in severe side effects. Herein, we describe the design, synthesis and evaluation of new synthetic compounds that are capable of inhibiting NFATc activity in a dose-dependent manner, without interfering on CN phosphatase activity. These compounds were designed using the structure-based pharmacophore model of a peptide-derived PxIxIT sequence binding to calcineurin A subunit. Moreover, these compounds inhibit NFATc-dependent cytokine gene expression, secretion and proliferation of human T CD4+ cells. More importantly, compound 5a reduces tumor weight and shows a tendency to reduce tumor angiogenesis in an orthotopic immunocompetent mouse model of triple negative breast cancer, suggesting that 5a has tumor suppressor activity. These findings validate compound 5a as an agent with therapeutic activity against CN-NFATc and highlight its potential as a tool for drug development with therapeutic purposes.
Subject(s)
Calcineurin , Triple Negative Breast Neoplasms , Animals , Calcineurin/chemistry , Calcineurin/genetics , Calcineurin/metabolism , Calcineurin Inhibitors , Cyclosporine/pharmacology , Humans , Mice , NFATC Transcription Factors/metabolism , Phosphoric Monoester Hydrolases/metabolism , Triple Negative Breast Neoplasms/drug therapyABSTRACT
We report a simple reductive amination protocol to ligate two peptides, while simultaneously installing a ß-turn mimic at the ligation junction. This strategy uses commercially available materials, mild chemical conditions, and a chemoselective ligation reaction of unprotected peptide substrates accessed through standard solid phase methods. This system was implemented in a designed ß-hairpin system, and biophysical analysis demonstrates effective mimicry of the ß-turn.
