SIGNIFICANT ELEVATION OF TUMOR-ASSOCIATED ISOFORMS OF SOLUBLE CD44 INSERUM OF NORMAL INDIVIDUALS CAUSED BY CIGARETTE-SMOKING

While performing a prospective study on sCD44 variant isoforms as tumo ur markers in certain malignancies, we detected relevant differences i n the control group between non-smokers and smokers. For a detailed ev aluation of these findings, serum levels of sCD44 variant proteins, in cluding sequences encoded by exon v5 and exon v6, respectively, were a djusted to sex, age and smoking habit. We were able to demonstrate a s ignificant elevation of serum levels of sCD44v5 and sCD44v6 in normal individuals due to cigarette smoking (non-smokers to smokers: sCD44v5: 33 +/- 11 mu g/l to 62 +/- 30 mu g/l; sCD44v6: 142 +/- 34 mu g/l to 2 32 +/- 86 mu g/l). Stepwise multiple linear regression analysis of the concentrations of sCD44v5 and sCD44v6 on the possible influence facto rs sex, age and smoking habit revealed cigarette smoking as the only f actor influencing these isoforms (both p much less than 0.001). Furthe r investigations have to elucidate a possible clinical importance of t hese findings in smokers. However, in patients with suspected or prove n malignancy the diagnostic specifity of sCD44v5 and sCD44v6 is dimini shed due to this observation.