Discovery and evaluation of nNav1.5 sodium channel blockers with potent cell invasion inhibitory activity in breast cancer cells

Abstract

Voltage-gated sodium channels (VGSC) are a well-established drug target for anti-epileptic, anti-arrhythmic and pain medications due to their presence and the important roles that they play in excitable cells. Recently, their presence has been recognized in non-excitable cells such as cancer cells and their overexpression has been shown to be associated with metastatic behavior in a variety of human cancers. The neonatal isoform of the VGSC subtype, Na1.5 (nNa1.5) is overexpressed in the highly aggressive human breast cancer cell line, MDA-MB-231. The activity of nNa1.5 is known to promote the breast cancer cell invasion in vitro and metastasis in vivo, and its expression in primary mammary tumors has been associated with metastasis and patient death. Metastasis development is responsible for the high mortality of breast cancer and currently there is no treatment available to specifically prevent or inhibit breast cancer metastasis. In the present study, a 3D-QSAR model is used to assist the development of low micromolar small molecule VGSC blockers. Using this model, we have designed, synthesized and evaluated five small molecule compounds as blockers of nNa1.5-dependent inward currents in whole-cell patch-clamp experiments in MDA-MB-231 cells. The most active compound identified from these studies blocked sodium currents by 34.9 ± 6.6% at 1 μM. This compound also inhibited the invasion of MDA-MB-231 cells by 30.3 ± 4.5% at 1 μM concentration without affecting the cell viability. The potent small molecule compounds presented here have the potential to be developed as drugs for breast cancer metastasis treatment.

Sodium homeostasis in the tumour microenvironment

“…Several studies have examined whether normalising tumour [Na + ] might be a useful treatment strategy. The use of VGSC inhibitors to prevent cancer growth and metastasis has been investigated in several preclinical studies (162,(213)(214)(215), and is currently the subject of several ongoing clinical trials (Table 2). In support of this, in retrospective observational studies, VGSC-inhibiting tricyclic antidepressants and antiepileptic medications have been shown to associate with reduced incidence of several common cancers including lung and colorectal cancer and glioma (216,217).…”

Bioelectric Control of Metastasis in Solid Tumors

“…Rat prostate and human breast cancer cell line electrotaxis is reduced when tetrodotoxin or other blockers of VGSCs are administered. 160,161 Although the mechanism of VGSC-driven electrotaxis is not well understood, it may involve an alteration in Ca 2+ concentration, phosphorylation of cytoskeletal components via kinase activation, or direct interaction with the cytoskeleton via the beta subunits as described in previous sections. 149 Although many cancer cell types can undergo electrotaxis, their response varies depending both on the type of cancer and the metastatic potential.…”

Rock inhibition promotes NaV1.5 sodium channel-dependent SW620 colon cancer cell invasiveness

“…In colon and breast cancers, the activity of Na V 1.5 results in a small but persistent entry of Na + at the basal membrane potential, that was demonstrated to promote extracellular matrix degradation, cancer cell invasiveness in vitro 30,31,36,39,44,55 , primary tumour growth and metastases development in animal models 40,41 . This paved the way for the development of new small inhibitors of Na V 56 or to the repurposing of clinically used inhibitors for anticancer treatments 32,40,41,57,58 . On the opposite, drugs promoting Na V activity in cancer cells, such as the alkaloid veratridine, importantly increase invasive behaviours in in vitro experiments 31,32,44 .…”