The in vitro anticancer effects of FS48 from salivary glands of Xenopsylla cheopis on NCI-H460 cells via its blockage of voltage-gated K+ channels.

Voltage-gated K⁺ (K_v) channels play a role in the cellular processes of various cancer cells, including lung cancer cells. We previously identified and reported a salivary protein from the Xenopsylla cheopis, FS48, which exhibited inhibitory activity against K_v1.1-1.3 channels when assayed in HEK 293T cells. However, whether FS48 has an inhibitory effect on cancer cells expressing Kv channels is unclear. The present study aims to reveal the effects of FS48 on the K_v channels and the NCI-H460 human lung cancer cells through patch clamp, MTT, wound healing, transwell, gelatinase zymography, qRT-PCR and WB assays. The results demonstrated that FS48 can be effective in suppressing the K_v currents, migration, and invasion of NCI-H460 cells in a dose-dependent manner, despite the failure to inhibit the proliferation. Moreover, the expression of K_v1.1 and K_v1.3 mRNA and protein were found to be significantly reduced. Finally, FS48 decreases the mRNA level of MMP-9 while increasing TIMP-1 mRNA level. The present study highlights for the first time that blood-sucking arthropod saliva-derived protein can inhibit the physiological activities of tumour cells via the Kv channels. Furthermore, FS48 can be taken as a hit compound against the tumour cells expressing K_v channels.