Plasma concentrations of reputed tumor-associated soluble CD44 isoforms (v5 and v6) in smokers are dose related and decline on smoking cessation

There is some evidence to suggest that smoking may affect circulating level s of CD44 (sCD44) molecules. Therefore, we investigated the effect of smoki ng on the circulating level of sCD44 by comparing the change in total sCD44 , sCD44v5, and sCD44v6 concentrations over 1 year in a group of people who quit smoking (n = 30) and a control group of people who continued to smoke (n = 30), Smoking status and compliance were monitored by analysis of plasm a cotinine and expired CO levels and also by self-reported tobacco use. We show a dose-dependent relationship between smoke intake and baseline plasma concentrations of reputed tumor-associated CD44 variant isoforms (sCD44v5 and sCD44v6) in smokers (n = 60), There was a significant decline in the le vel of both sCD44v5 and sCD44v6 in quitters as compared with continuing smo kers [-13.2 (95% confidence interval, -7.6 to -18.8; P < 0.001) and -62.2 n g/ml (95% confidence interval, -33.9 to -90.6; P < 0.001), respectively, bu t not in the total sCD44 concentration, These results show that the increas ed concentrations of sCD44v5 and sCD44v6 in smokers are dose related and re versible and suggest that the attributed diagnostic specificity and prognos tic value of sCD44 molecules in malignant and inflammatory disease may be a ffected by smoking status.