Voltage-Gated Sodium Channel NaV1.5 Controls NHE-1-Dependent Invasive Properties in Colon Cancer Cells.

Colorectal cancer (CRC) is the second leading cause of death worldwide, with 0.9 million deaths per year. The metastatic stage of the disease is identified in about 20% of cases at the first diagnosis and is associated with low patient-survival rates. Voltage-gated sodium channels (NaV) are abnormally overexpressed in several carcinomas including CRC and are strongly associated with the metastatic behavior of cancer cells. Acidification of the extracellular space by Na+/H+ exchangers (NHE) contributes to extracellular matrix degradation and cell invasiveness. In this study, we assessed the expression levels of pore-forming α-subunits of NaV channels and NHE exchangers in tumor and adjacent non-malignant tissues from colorectal cancer patients, CRC cell lines and primary tumor cells. In all cases, SCN5A (gene encoding for NaV1.5) was overexpressed and positively correlated with cancer stage and poor survival prognosis for patients. In addition, we identified an anatomical differential expression of SCN5A and SLC9A1 (gene encoding for NHE-1) being particularly relevant for tumors that originated on the sigmoid colon epithelium. The functional activity of NaV1.5 channels was characterized in CRC cell lines and the primary cells of colon tumors obtained using tumor explant methodologies. Furthermore, we assessed the performance of two new small-molecule NaV1.5 inhibitors on the reduction of sodium currents, as well as showed that silencing SCN5A and SLC9A1 substantially reduced the 2D invasive capabilities of cancer cells. Thus, our findings show that both NaV1.5 and NHE-1 represent two promising targetable membrane proteins against the metastatic progression of CRC.

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

The acquisition of invasive capacities by carcinoma cells, i.e. their ability to migrate through and to remodel extracellular matrices, is a determinant process leading to their dissemination and to the development of metastases. these cancer cell properties have often been associated with an increased Rho-ROCK signalling, and ROCK inhibitors have been proposed for anticancer therapies. In this study we used the selective ROCK inhibitor, Y-27632, to address the participation of the Rho-ROCK signalling pathway in the invasive properties of SW620 human colon cancer cells. Contrarily to initial assumptions, Y-27632 induced the acquisition of a pro-migratory cell phenotype and increased cancer cell invasiveness in both 3- and 2-dimensions assays. This effect was also obtained using the other ROCK inhibitor Fasudil as well as with knocking down the expression of ROCK-1 or ROCK-2, but was prevented by the inhibition of NaV1.5 voltage-gated sodium channel activity. Indeed, ROCK inhibition enhanced the activity of the pro-invasive NaV1.5 channel through a pathway that was independent of gene expression regulation. In conclusions, our evidence identifies voltage-gated sodium channels as new targets of the ROCK signalling pathway, as well as responsible for possible deleterious effects of the use of ROCK inhibitors in the treatment of cancers.

Sodium Channel Nav1.5 Controls Epithelial-to-Mesenchymal Transition and Invasiveness in Breast Cancer Cells Through its Regulation by the Salt-Inducible Kinase-1.

Loss of epithelial polarity and gain in invasiveness by carcinoma cells are critical events in the aggressive progression of cancers and depend on phenotypic transition programs such as the epithelial-to-mesenchymal transition (EMT). Many studies have reported the aberrant expression of voltage-gated sodium channels (NaV) in carcinomas and specifically the NaV1.5 isoform, encoded by the SCN5A gene, in breast cancer. NaV1.5 activity, through an entry of sodium ions, in breast cancer cells is associated with increased invasiveness, but its participation to the EMT has to be clarified. In this study, we show that reducing the expression of NaV1.5 in highly aggressive human MDA-MB-231 breast cancer cells reverted the mesenchymal phenotype, reduced cancer cell invasiveness and the expression of the EMT-promoting transcription factor SNAI1. The heterologous expression of NaV1.5 in weakly invasive MCF-7 breast cancer cells induced their expression of both SNAI1 and ZEB1 and increased their invasive capacities. In MCF-7 cells the stimulation with the EMT-activator signal TGF-ß1 increased the expression of SCN5A. Moreover, the reduction of the salt-inducible kinase 1 (SIK1) expression promoted NaV1.5-dependent invasiveness and expression of EMT-associated transcription factor SNAI1. Altogether, these results indicated a prominent role of SIK1 in regulating NaV1.5-dependent EMT and invasiveness.

Usefulness of confocal laser endomicroscopy for predicting postoperative recurrence in patients with Crohn's disease: a pilot study.

BACKGROUND AND AIMS: Confocal laser endomicroscopy (CLE) has been shown to predict relapse in inflammatory bowel disease, but its value in the detection of postoperative recurrence in Crohn's disease (CD) is unknown. The aims of this pilot study performed in patients with CD after ileocolonic resection were to compare the macroscopic appearance of the neoterminal ileum, according to the endoscopic Rutgeerts score, with the microscopic findings provided by CLE 6 to 12 months after surgery and to assess the predictive values of CLE-generated parameters for predicting further recurrence in patients with postoperative endoscopic remission. METHODS: In 25 consecutive patients with CD within 6 to 12 months of surgery, the neoterminal ileum was examined by standard white-light endoscopy (Rutgeerts scale) followed by CLE (Watson grade). Only patients without endoscopic recurrence (Rutgeerts i0 and i1) were then followed endoscopically and clinically (median follow-up 38 months). RESULTS: At the time of the first postoperative colonoscopy, 18 patients (72%) were in endoscopic remission, and 7 (28%) experienced an endoscopic recurrence (Rutgeerts ≥i2). The Rutgeerts score was significantly correlated with the Watson score (ρ = 0 .73; P < .0001). The Watson scores at baseline were significantly higher in patients with further endoscopic recurrence (median 2.0; interquartile range [IQR] 1.5-2.0) than in those with endoscopic remission (median 1.0; IQR 1.0-1.0; P = .032) and were significantly higher in patients with clinical relapse (medium 2.0, IQR 2.0-2.0) compared with those in clinical remission (median 1.0; IQR 1.0-1.0; P = .036). CONCLUSIONS: CLE could be useful in monitoring patients with CD after intestinal resection. Further studies with a larger population are necessary to confirm these preliminary results.