tetrodotoxin and Carcinoma--Squamous-Cell

The protein voltage-gated sodium channel Nav1.5 is highly upregulated in various types of cancer and, in general, promotes cancer cell invasiveness and metastatic progression. A previous study found that Nav1.5 was highly expressed in poorly differentiated oral squamous cell carcinoma (OSCC). However, whether Nav1.5 enhances invasiveness and metastasis of OSCC are still unknown. In this study, we found that Nav1.5 was highly expressed in OSCC cell lines compared with normal oral keratinocyte HOK cell line by using western blot analysis. CCK-8 assay results revealed that downregulation of Nav1.5 expression by its specific siRNA reduced proliferation of OSCC HSC-3 cells. Moreover, transwell assay results showed Nav1.5 knockdown significantly inhibited migration and invasion of HSC-3 cells. Meanwhile, qRT-PCR and western blot analysis results showed that epidermal growth factor (EGF) induced Nav1.5 expression in a time- and dose-dependent manner. In addition, EGF promoted proliferation, migration and invasion of HSC-3 cells. Importantly, the Nav1.5 inhibitor tetrodotoxin significantly inhibited the proliferation of HSC-3 cells and impeded the migration and invasion of HSC-3 cells. Furthermore, it was found that siRNA-mediated knockdown of Nav1.5 also lessened the proliferation of HSC-3 cells and blocked the migration and invasion of HSC-3 cells. Taken together, these results indicate that Nav1.5 is involved in the progression of OSCC and Nav1.5 promotes the proliferation, migration and invasion of OSCC cells.

Topics: Carcinoma, Squamous Cell; Cell Line; Cell Line, Tumor; Cell Movement; Cell Proliferation; Epidermal Growth Factor; Gene Expression Regulation, Neoplastic; Humans; Mouth Neoplasms; NAV1.5 Voltage-Gated Sodium Channel; Neoplasm Invasiveness; RNA Interference; Sodium Channel Blockers; Tetrodotoxin

Patch clamp method in outside-out configuration was used to search for cation channels which possibly mediate sodium influx through plasma membrane in A-431 carcinoma cells. We found four types of nonvoltage-gated Na-conducting channel. The first of 9-10 pS conductance (145 mM Na+, 30 degrees C) seems to be Na-selective; three others were characterized with conductance values of 24, 35 and 65 pS and lower selectivity among cations. Na-selective channels (9-10 pS) were not blocked by tetrodotoxin (1 microM). External application of amiloride (0.1-2 mM) resulted in a reversible inhibition of single currents through Na-selective channels.

Topics: Amiloride; Carcinoma, Squamous Cell; Cell Membrane; Electrochemistry; Humans; Sodium Channels; Tetrodotoxin; Tumor Cells, Cultured

A BALB/c murine monoclonal antibody against the trichothecene mycotoxin T-2 was generated. The antibody, designated HD11, specifically bound T-2 mycotoxin. The binding of HD11 to T-2 conjugated to bovine serum albumin was inhibited by free T-2 toxin but not by the water-soluble heterocyclic guanidines saxitoxin and tetrodotoxin. The T-2 detection limit in an enzyme-linked immunosorbent assay with HD11 was in the nanogram range. The in vitro cytotoxicity of T-2, as measured by the inhibition of radiolabeled leucine uptake of the human epidermoid carcinoma Hep-2 and KB cell lines, was completely reversed by the addition of HD11. Rabbit anti-idiotypic antibodies specific for HD11 were generated and characterized.

Topics: Antibodies, Anti-Idiotypic; Antibodies, Monoclonal; Carcinoma, Squamous Cell; Cell Survival; Enzyme-Linked Immunosorbent Assay; Humans; Immunoglobulin Idiotypes; Saxitoxin; Serum Albumin, Bovine; Sesquiterpenes; T-2 Toxin; Tetrodotoxin; Tumor Cells, Cultured