Author:

Keywords:

G0E7120N#55530835, 12W7822N#56283404, G0A4919N#54971236

Abstract:

The World Cancer Report of 2020 states that cancer remains one of the leading causes of disease, mortality, and economic losses worldwide. While there have been considerable improvements in treatment and survival times for patients suffering from a number of different types of cancer, there is still an urgent need to identify and discover novel molecular targets and therapies with curative intent. The use of conventional chemotherapeutic agents for cancer therapy is often limited because of their severe side effects and the development of resistance. The implication and relevance of voltage-gated potassium channels in cancer has become a well-established concept. Among over 70 different family members, KV11.1, KV1.3 and KV10.1 are the best studied and documented. This project concentrates on KV10.1 and KV1.3 because targeting KV11.1 has the risk of generating malignant arrhythmia. Despite the available evidence, translation into better clinical practice is still waiting for the development of more potent and selective KV10.1 and KV1.3 inhibitors. During this PhD project, both small molecules and animal venoms were explored for their activity on KV10.1 and KV1.3. The tested venoms and peptides are not included in this thesis; however, an extensive overview of the tested small molecules is given. In Chapter 2, a novel structural class of KV10.1 inhibitors was discovered by a computational ligand-based approach. The novel low micromolar KV10.1 inhibitor ZVS-08 was identified, which is based on a diarylamine scaffold. By synthesizing analogues, the potency of KV10.1 inhibition could be increased. Analogue compound 1 inhibited the KV10.1 channel with an IC50 value of 740 nM and showed a slight increase in selectivity on the KV11.1 channel. Cancer cell proliferation was inhibited at a concentration of 5.48 μM in KV10.1 expressing cell line, while the cancerous and non-cancerous cell lines without KV10.1 expression were not inhibited. With the broad window between mutagenic activity and inhibition of KV10.1, the new compounds show promising potential for further development in cancer therapy. In Chapter 3, a novel structural class of KV1.3 inhibitors was discovered by a 3D similarity search and a subsequent structural optimization. Two hit compounds with diarylamine scaffold were identified and based on this, novel thiophen-based potent and selective KV1.3 inhibitors were successfully prepared. A potent and appropriately selective nanomolar KV1.3 inhibitor 44 was identified, which contains 3-thiophene and tetrahydropyran scaffolds. It was demonstrated that proliferation of the Panc-1 cancer cell line could be inhibited with new KV1.3 inhibitors. Hit compound 4 induced significant apoptosis in Colo-357 tumor spheroids. Based on efficacy data in PDAC cell lines and Colo-357 tumor spheroids, it can be assumed that newly developed KV1.3 inhibitors do not reach the mitochondrial KV1.3 channels required for induction of apoptosis. There is an opportunity to further develop the new structural class of potent and selective KV1.3 inhibitors into mitochondrial KV1.3 inhibitors by adding mitochondrial targeting moieties. In Chapter 4, the effect of simplified and spirocyclic bromo- and chlorotyrosine analogs on KV10.1 was investigated. IT-26 was found to be the most potent compound of the three series, with an IC50 of 11.23 ± 0.68 µM on the manual voltage-clamp. Unfortunately, most of these compounds were equally active on KV11.1, which is a major off-target. To evaluate if these new compounds are suitable for further optimization into possible anticancer compounds, they should be tested (into more detail) on KV11.1 and on cancer cell lines.