Effects of carbocisteine on sialyl-Lewis x expression in an airway carcinoma cell line stimulated with tumor necrosis factor-α

Carbocisteine is a mucoregulatory drug normalizing sialic acid and fucose contents in mucins through the regulation of glycosyltransferase activities. Tumor necrosis factor (TNF)-α-induced overexpression of sialyl-Lewis x epitopes, containing sialic acid and fucose, in mucins were previously reported to be regulated by glycosyltransferase mRNAs expression through phosphatidyl inositol-specific phospholipase C (PI-PLC) signaling pathways [Ishibashi, Y., Inouye, Y., Okano, T., Taniguchi, A., 2005. Regulation of sialyl-Lewis x epitope expression by TNF-α and EGF in an airway carcinoma cell line. Glycoconj. J. 22, 53-62]. To investigate the mechanism behind the mucoregulatory action of carbocisteine, the present study evaluated the effects of carbocisteine on TNF-α-induced overexpression of sialyl-Lewis x epitopes in NCI-H292 cells. 100 μg/ml of carbocisteine was able to inhibit the TNF-α-induced expression of hST3GallV mRNA, FUT3 mRNA, C2/4GnT mRNA and sialyl-Lewis x epitopes as well as the TNF-α-induced activity of PI-PLC in NCI-H292 cells. These findings suggest that carbocisteine may normalize the sialyl-Lewis x epitopes expression in mucins through the inhibition of cellular PI-PLC activity in vivo.