Voltage-gated potassium ion channels KV1.3 belong to a group of ion channels that are activated by a change in membrane potential. Increased expression of cell membrane and inner mitochondrial membrane channels is found in some specific types of cancer cells, which means that by developing inhibitors of KV1.3 channels we could potentially discover new cancer therapies.
In this Master's thesis, we synthesised four known inhibitors of KV1.3 potassium channels (compounds 7, 8a, 8b and 14) and tested their anticancer activity. We also tested their cytotoxicity on normal cells. One of the compounds (compound 14) contained the triphenylphosphonium ion (TPP+) transport group, which enables better distribution of the inhibitors in the mitochondria, where they exert inhibition of the channels and anticancer activity on cancer cells. Three of the inhibitors (compounds 7, 8a and 8b) without TPP+ showed low cytotoxicity in the Panc-1 cancer cell line, while they showed no activity in Colo357 cells. Compound 14 showed strong cytotoxicity in cancer cell line B16F10 and induced a significant level of apoptosis in Colo357. The resynthesised compounds showed no specific anticancer activity. Compounds 7, 8a and 8b showed cytotoxic effects on the normal cell line hTERT-RPE1 and compound 14 showed the same effect on the normal cell lines L929 and C2C12.
We also synthesised two new potential mitochondrial inhibitors 13 and 15 whose structures also contained TPP+. The compounds exhibited potent cytotoxic effects on cancer cell lines B16F10 and Colo357 and induced high levels of apoptosis in Colo357 cells. Compound 13 induced apoptosis more rapidly and its cytotoxic effect was stronger. Their anticancer effects also proved to be non-specific, exerting a strong cytotoxic effect on non-cancerous cell lines L929 and C2C12. Compound 13 also induced a high degree of apoptosis in the normal cell line hTERT-RPE1. The structure of compound 13 contained the cis-configuration and a longer linker between TPP and carbamate binding, most likely leading to a stronger anticancer activity. However, its activity in normal cell lines was also the highest among all compounds. Therefore, compounds 14 and 15 proved to be possibly better and safer choices for potential cancer therapy.
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