Mirko Zaja

Analogues of morphanthridine and the tear gas dibenz[b,f][1,4]oxazepine (CR) as extremely potent activators of the human transient receptor potential ankyrin 1 (TRPA1) channel.

The TRPA1 channel can be considered as a key biological sensor to irritant chemicals. In this paper, the discovery of 11H-dibenz[b,e]azepines (morphanthridines) and dibenz[b,f][1,4]oxazepines is described as extremely potent agonists of the TRPA1 receptor. This has led to the discovery that most of the known tear gases are potent TRPA1 activators. The synthesis and biological activity of a number of substituted morphanthridines and dibenz[b,f][1,4]oxazepines have given insight into the SAR around this class of TRPA1 agonists, with EC(50) values ranging from 1 μM to 0.1 nM. Compounds 6 and 32 can be considered as the most potent TRPA1 agonists known to date, with 6 now being used successfully as a screening tool in the discovery of TRPA1 antagonists. The use of ligands such as 6 and 32 as pharmacological tools may contribute to the basic knowledge of the TRPA1 channel and advance the development of TRPA1 antagonists as potential treatment for conditions involving TRPA1 activation, including asthma and pain.

Design and Synthesis of a Novel Series of Bicyclic Heterocycles As Potent γ-Secretase Modulators

The design and the synthesis of several chemical subclasses of imidazole containing γ-secretase modulators (GSMs) is described. Conformational restriction of pyridone 4 into bicyclic pyridone isosteres has led to compounds with high in vitro and in vivo potency. This has resulted in the identification of benzimidazole 44a as a GSM with low nanomolar potency in vitro. In mouse, rat, and dog, this compound displayed the typical γ-secretase modulatory profile by lowering Aβ42 and Aβ40 levels combined with an especially pronounced increase in Aβ38 and Aβ37 levels while leaving the total levels of amyloid peptides unchanged.

Difluoro-dioxolo-benzoimidazol-benzamides As Potent Inhibitors of CK1δ and ε with Nanomolar Inhibitory Activity on Cancer Cell Proliferation

Deregulation of CK1 (casein kinase 1) activity can be involved in the development of several pathological disorders and diseases such as cancer. Therefore, research interest in identifying potent CK1-specific inhibitors is still increasing. A previously published potent and selective benzimidazole-derived CK1δ/ε-specific inhibitor compound with significant effects on several tumor cell lines was further modified to difluoro-dioxolo-benzoimidazole derivatives displaying remarkable inhibitory effects and increased intracellular availability. In the present study, we identified two heterocyclic molecules as new CK1-specific inhibitor compounds with favorable physicochemical properties and notable selectivity in a kinome-wide screen. Being compared to other CK1 isoforms, these compounds exhibited advanced isoform selectivity toward CK1δ. Moreover, newly designed compounds showed increased growth inhibitory activity in a panel of different tumor cell lines as determined by analyses of cell viability and cell cycle distribution. In summary, presented lead optimization resulted in new highly selective CK1δ-specific small molecule inhibitors with increased biological activity.

DYRK1B as therapeutic target in Hedgehog/GLI-dependent cancer cells with Smoothened inhibitor resistance

A wide range of human malignancies displays aberrant activation of Hedgehog (HH)/GLI signaling, including cancers of the skin, brain, gastrointestinal tract and hematopoietic system. Targeting oncogenic HH/GLI signaling with small molecule inhibitors of the essential pathway effector Smoothened (SMO) has shown remarkable therapeutic effects in patients with advanced and metastatic basal cell carcinoma. However, acquired and de novo resistance to SMO inhibitors poses severe limitations to the use of SMO antagonists and urgently calls for the identification of novel targets and compounds. Here we report on the identification of the Dual-Specificity-Tyrosine-Phosphorylation-Regulated Kinase 1B (DYRK1B) as critical positive regulator of HH/GLI signaling downstream of SMO. Genetic and chemical inhibition of DYRK1B in human and mouse cancer cells resulted in marked repression of HH signaling and GLI1 expression, respectively. Importantly, DYRK1B inhibition profoundly impaired GLI1 expression in both SMO-inhibitor sensitive and resistant settings. We further introduce a novel small molecule DYRK1B inhibitor, DYRKi, with suitable pharmacologic properties to impair SMO-dependent and SMO-independent oncogenic GLI activity. The results support the use of DYRK1B antagonists for the treatment of HH/GLI-associated cancers where SMO inhibitors fail to demonstrate therapeutic efficacy.