Voltage-gated Na + channels confer invasive properties on human prostate cancer cells

Abstract

Prostate cancer is the second leading cause of cancer deaths in American males, resulting in an estimated 37,000 deaths annually, typically the result of metastatic disease. A consequence of the unsuccessful androgen ablation therapy used initially to treat metastatic disease is the emergence of androgen-insensitive prostate cancer, for which there is currently no prescribed therapy. Here, three related human prostate cancer cell lines that serve as a model for this dominant form of prostate cancer metastasis were studied to determine the correlation between voltage-gated sodium channel expression/function and prostate cancer metastatic (invasive) potential: the non-metastatic, androgen-dependent LNCaP LC cell line and two increasingly tumorogenic, androgen-independent daughter cell lines, C4 and C4-2. Fluorometric in vitro invasion assays indicated that C4 and C4-2 cells are more invasive than LC cells. Immunoblot analysis showed that voltage-gated sodium channel expression increases with the invasive potential of the cell line, and this increased invasive potential can be blocked by treatment with the specific voltage-gated sodium channel inhibitor, tetrodotoxin (TTX). These data indicate that increased voltage-gated sodium channel expression and function are necessary for the increased invasive potential of these human prostate cancer cells. When the human adult skeletal muscle sodium channel Na(v1.4) was expressed transiently in each cell line, there was a highly significant increase in the numbers of invading LC, C4, and C4-2 cells. This increased invasive potential was reduced to control levels by treatment with TTX. These data are the first to indicate that the expression of voltage-gated sodium channels alone is sufficient to increase the invasive potential of non-metastatic (LC cells) as well as more aggressive cells (i.e., C4 and C4-2 cells). Together, the data suggest that increased voltage-gated sodium channel expression alone is necessary and sufficient to increase the invasive potential of a set of human prostate cancer cell lines that serve as a model for prostate cancer metastasis.

Effects of Hedera helix L. extracts on rat prostate cancer cell proliferation and motility

“…In addition, 200 nM TTX did not demonstrate toxicity against the two cell lines. Metastatic properties of Mat-LyLu and AT-2 cells are closely associated with VGSCs, as has been demonstrated in studies on TTX, which specifically blocks VGSCs (4,7,8,11). In the present study, 200 nM TTX was used as the positive control, as it has been previously reported that TTX does not produce changes in the proliferation of either cell line even at higher doses (600 nM and 6 µM) than 200 nM (5,7,27).…”

“…Ion channels regulate, and stimulate numerous behavioral changes in cells that are associated with cancer and metastasis, including cell movement (elongation and lateral motility) (4,5), migration, galvanotaxis (6) and invasion (7,8). A number of in vitro (9)(10)(11) and in vivo (12) studies performed using tetrodotoxin (TTX), which specifically blocks voltage-gated sodium channels (VGSCs) (13), have suggested that the plasma membrane of prostate cancer cells may gain a more excitable phenotype due to increased VGSC expression, and thus malignancy is able to progress. Bennett et al (11) demonstrated that VGSC expression was 'necessary' and 'enough' for the invasiveness of prostate cancer cells.…”

“…A number of in vitro (9)(10)(11) and in vivo (12) studies performed using tetrodotoxin (TTX), which specifically blocks voltage-gated sodium channels (VGSCs) (13), have suggested that the plasma membrane of prostate cancer cells may gain a more excitable phenotype due to increased VGSC expression, and thus malignancy is able to progress. Bennett et al (11) demonstrated that VGSC expression was 'necessary' and 'enough' for the invasiveness of prostate cancer cells. Prostate cancer tends to invade the bones, lungs and lymph nodes (14).…”

β-Subunits of voltage-gated sodium channels in human prostate cancer: quantitative in vitro and in vivo analyses of mRNA expression

“…This may explain why there is no need for a large increase in b1-expression (concomitant with the large increase in VGSCa-expression) in strongly metastatic CaP cells, and would also be consistent with overexpression of VGSCa alone in LNCaP cells being sufficient to increase significantly their in vitro invasiveness. 43 Despite the absence of a large increase in VGSCbexpression, these subunits might still have an important role in VGSC functioning in CaP, and thus in VGSCmediated potentiation of metastatic cell behaviours. Indeed, reducing b1-expression or perturbing its association with Na v 1.7 could alter key channel properties such as activation/inactivation and recovery from fast inactivation that would result in less VGSC activity and inhibition of VGSC-potentiated metastatic cell behaviour.…”

The Human Papilloma Virus – Ion Channel Link in Cancer: An Alternative Opportunity for Diagnosis and Therapy

“…Metastasis is a process where cells escape from a primary tumor, enter circulation (blood or lymph), migrate and invade other tissues, proliferate and form secondary tumors. In in vitro experiments, it has been shown that VGSCs are associated to proliferation, motility, and invasion of breast, lung, ovary and prostate cancer (Roger et al, 2003;Gao et al, 2010;Diss et al 2005;Chioni et al, 2010;Roger et al, 2007;House, et al, 2010;Bennett et al, 2004). In prostate cancer cells, the main VGSC overexpressed is the Na V 1.7 subunit, while in breast, colon and ovary the Na V 1.5 subunit is the predominant subunit overexpressed.…”