Reduction of caveolin 1 gene expression in lung carcinoma cell lines

Caveolae are plasma membrane microdomains that have been implicated in orga nizing and concentrating certain signaling molecules. Caveolins, constitute the main structural proteins of caveolae. Caveolae are abundant in termina lly differentiated cell types. However, caveolin-1 is down-regulated in tra nsformed cells and may have a potential tumor suppressor activity. In the l ung, caveolae are present in the endothelium, smooth muscle cells, fibrobla sts as well as in type I pneumocytes. The presence of caveolae and caveolin expression in the bronchial epithelium, although probable, has not been in vestigated in human. We were interested to see if the bronchial epithelia e xpress caveolins and if this expression was modified in cancer cells. We th us tested for caveolin-1 and -2 expression several bronchial epithelial pri mary cell lines as well as eight lung cancer cell lines and one larynx tumo r cell line. Both caveolin-1 and -2 are expressed in all normal bronchial c ell lines. With the exception of Calu-1 cell line, all cancer cell lines sh owed very low or no expression of caveolin-1 while caveolin-2 expression wa s similar to the one observed in normal bronchial epithelial cells. (C) 199 9 Academic Press.