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

Figures

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  Figure 1. Structures of known representative KV1.3 inhibitors. (A) PAP-1 (1). (B) PAC (2). (C) Clofazimine (3) (D) TVS-06 (4). (E) TVS-12 (5).

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  Figure 2. Design of new KV1.3 inhibitors of structural Types I–VI.

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  Figure 3. Raw traces of KV1.3 currents in control conditions in ND96 (black line) and after addition of PAP-1 (light orange line), 14 (blue line), 37 (red line), 43 (orange line), and 44 (green line). The dotted line indicates the zero current level. Measured by manual voltage clamp on Xenopus laevis oocytes.

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  Figure 4. Selectivity determination of PAP-1 (1) screened at a concentration of 10 µM (HiClamp Xenopus laevis heterologous expression system) on a panel of ion channels. (**** p < 0.0001, Mean ± S.E.M, N = 3–12).

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  Figure 5. Selectivity determination of 14, 37, 43, and 44 screened at a concentration of their IC50 values for KV1.3 on a panel of ion channels. **** p < 0.0001, *** p < 0.001, ** p < 0.01 * p < 0.05, Mean ± S.E.M, N = 3–12).

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  Figure 6. Effects on pancreatic cancer cell lines in 2D and 3D cell cultures. (A) Growth curves (culture confluence measured through phase contrast imaging) of Panc-1 cells in the presence of the indicated compounds (100 µM) or the vehicle (DMSO, black symbols). Mean ± S.E.M, N = 9. (B) The equivalent experiment on Colo-357 cells revealed that the growth inhibition was cell-type specific. Mean ± S.E.M, N = 15. The inhibition 24 h after the start of treatment is quantified in (C,D) for the data presented in (A,B) respectively. (E) Apoptosis measured as caspase 3/7 activity on Panc-1 tumor spheroids in the presence of the indicated compounds. (F) Apoptosis in Colo-357 tumor spheroids (p < 0.001, Mean ± S.E.M, N = 4).

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  Figure 7. Pharmacophore model of new KV1.3 inhibitors. The model was prepared in the Ligandscout 4.4 Expert (Inte:Ligand GmbH) [22,29] using molecules with inhibition of KV1.3 higher than 75% at 10 µM concentration. Pharmacophore features represent: hydrophobic interactions, yellow spheres; aromatic interactions, blue discs; hydrogen bond donor, green arrow; hydrogen bond acceptors, red arrows. The pharmacophore model shows the most important features of KV1.3 inhibitors with the most potent compound 44 aligned to the pharmacophore model.