Immunosuppressive effects of new thiophene-based KV1.3 inhibitors.

Voltage-gated potassium channel KV1.3 inhibitors have been shown to be effective in preventing T-cell proliferation and activation by affecting intracellular Ca2+ homeostasis. Here, we present the structure-activity relationship, KV1.3 inhibition, and immunosuppressive effects of new thiophene-based KV1.3 inhibitors with nanomolar potency on K+ current in T-lymphocytes and KV1.3 inhibition on Ltk- cells. The new KV1.3 inhibitor trans-18 inhibited KV1.3 -mediated current in phytohemagglutinin (PHA)-activated T-lymphocytes with an IC50 value of 26.1 nM and in mammalian Ltk- cells with an IC50 value of 230 nM. The KV1.3 inhibitor trans-18 also had nanomolar potency against KV1.3 in Xenopus laevis oocytes (IC50 = 136 nM). The novel thiophene-based KV1.3 inhibitors impaired intracellular Ca2+ signaling as well as T-cell activation, proliferation, and colony formation.

Correction: Gubic et al. Design of New Potent and Selective Thiophene-Based KV1.3 Inhibitors and Their Potential for Anticancer Activity. Cancers 2022, 14, 2595.

In the original publication [...].

New Diarylamine KV10.1 Inhibitors and Their Anticancer Potential.

Expression of the voltage-gated potassium channel KV10.1 (Eag1) has been detected in over 70% of human cancers, making the channel a promising new target for new anticancer drug discovery. A new structural class of KV10.1 inhibitors was prepared by structural optimisation and exploration of the structure-activity relationship of the previously published hit compound ZVS-08 (1) and its optimised analogue 2. The potency and selectivity of the new inhibitors between KV10.1 and hERG were investigated using whole-cell patch-clamp experiments. We obtained two new optimised KV10.1 inhibitors, 17a and 18b, with improved nanomolar IC50 values of 568 nM and 214 nM, respectively. Compound 17a exhibited better ratio between IC50 values for hEAG1 and hERG than previously published diarylamine inhibitors. Compounds 17a and 18b moderately inhibited the growth of the KV10.1-expressing cell line MCF-7 in two independent assays. In addition, 17a and 18b also inhibited the growth of hERG-expressing Panc-1 cells with higher potency compared with MCF-7 cells. The main obstacle for newly developed diarylamine KV10.1 inhibitors remains the selectivity toward the hERG channel, which needs to be addressed with targeted drug design strategies in the future.

Design of New Potent and Selective Thiophene-Based KV1.3 Inhibitors and Their Potential for Anticancer Activity.

The voltage-gated potassium channel KV1.3 has been recognized as a tumor marker and represents a promising new target for the discovery of new anticancer drugs. We designed a novel structural class of KV1.3 inhibitors through structural optimization of benzamide-based hit compounds and structure-activity relationship studies. The potency and selectivity of the new KV1.3 inhibitors were investigated using whole-cell patch- and voltage-clamp experiments. 2D and 3D cell models were used to determine antiproliferative activity. Structural optimization resulted in the most potent and selective KV1.3 inhibitor 44 in the series with an IC50 value of 470 nM in oocytes and 950 nM in Ltk- cells. KV1.3 inhibitor 4 induced significant apoptosis in Colo-357 spheroids, while 14, 37, 43, and 44 significantly inhibited Panc-1 proliferation.

3D Pharmacophore-Based Discovery of Novel KV10.1 Inhibitors with Antiproliferative Activity.

(1) Background: The voltage-gated potassium channel KV10.1 (Eag1) is considered a near- universal tumour marker and represents a promising new target for the discovery of novel anticancer drugs. (2) Methods: We utilized the ligand-based drug discovery methodology using 3D pharmacophore modelling and medicinal chemistry approaches to prepare a novel structural class of KV10.1 inhibitors. Whole-cell patch clamp experiments were used to investigate potency, selectivity, kinetics and mode of inhibition. Anticancer activity was determined using 2D and 3D cell-based models. (3) Results: The virtual screening hit compound ZVS-08 discovered by 3D pharmacophore modelling exhibited an IC50 value of 3.70 µM against KV10.1 and inhibited the channel in a voltage-dependent manner consistent with the action of a gating modifier. Structural optimization resulted in the most potent KV10.1 inhibitor of the series with an IC50 value of 740 nM, which was potent on the MCF-7 cell line expressing high KV10.1 levels and low hERG levels, induced significant apoptosis in tumour spheroids of Colo-357 cells and was not mutagenic. (4) Conclusions: Computational ligand-based drug design methods can be successful in the discovery of new potent KV10.1 inhibitors. The main problem in the field of KV10.1 inhibitors remains selectivity against the hERG channel, which needs to be addressed in the future also with target-based drug design methods.

Targeting Cannabinoid Receptors: Current Status and Prospects of Natural Products.

Cannabinoid receptors (CB1 and CB2), as part of the endocannabinoid system, play a critical role in numerous human physiological and pathological conditions. Thus, considerable efforts have been made to develop ligands for CB1 and CB2, resulting in hundreds of phyto- and synthetic cannabinoids which have shown varying affinities relevant for the treatment of various diseases. However, only a few of these ligands are clinically used. Recently, more detailed structural information for cannabinoid receptors was revealed thanks to the powerfulness of cryo-electron microscopy, which now can accelerate structure-based drug discovery. At the same time, novel peptide-type cannabinoids from animal sources have arrived at the scene, with their potential in vivo therapeutic effects in relation to cannabinoid receptors. From a natural products perspective, it is expected that more novel cannabinoids will be discovered and forecasted as promising drug leads from diverse natural sources and species, such as animal venoms which constitute a true pharmacopeia of toxins modulating diverse targets, including voltage- and ligand-gated ion channels, G protein-coupled receptors such as CB1 and CB2, with astonishing affinity and selectivity. Therefore, it is believed that discovering novel cannabinoids starting from studying the biodiversity of the species living on planet earth is an uncharted territory.

Design and characterization of a novel structural class of Kv1.3 inhibitors.

The voltage-gated potassium channel Kv1.3 is involved in multiple autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis, diabetes mellitus type 1 and psoriasis. In many auto-immune diseases better treatment options are desired as existing therapies are often ineffective or become less effective over time, for which Kv1.3 inhibitors arise as promising candidates. In this study, five compounds were selected based on a 3D similarity searching methodology and subsequently screened ex vivo on the Kv1.3 channel. The screening resulted in two compounds inhibiting the Kv1.3 channel, of which TVS-12 was the most potent compound, while TVS-06 -although less potent- showed an excellent selectivity for Kv1.3. For both compounds the mechanism of action was investigated by an electrophysiological characterization on the Kv1.3 channel and three Kv1.3 mutants, designed to resemble the pore region of Kv1.2 channels. Structurally, the presence of a benzene ring and/or an oxane ring seems to cause a better interaction with the Kv1.3 channel, resulting in a 20-fold higher potency for TVS-12.