Expression of ras (p21) protein in plasma from exposed workers and from patients with lung disease

Oncogenes are involved with the regulation of cellular proliferation and th us could be important in the development of many cancers. Cells transformed in culture by ras genes can be activated either by the introduction of spe cific point mutations or by overexpression of the normal proto-oncogene. Th e ras genes encode a protein of 189 amino acids (molecular mass 21 kDa) des ignated as p21. ras p21 proteins are contained in all eukaryotic cells on t he inner surface of the plasma membrane. We measured ras p21 proteins in lu ng cancer patients, patients with chronic obstructive pulmonary disease (CO PD) and workers exposed to emissions from petrochemical plants and 1,3-buta diene and 1,3-butadiene/styrene. Proteins were separated by gel electrophor esis, transferred to a nitrocellulose membrane by Western blotting and dete cted by chemiluminescence. A monoclonal pan-ras antibody was used as the pr imary antibody. Optical densities of the peak area of the protein bands wer e calculated and values which were two standard deviations above negative c ontrol means were considered positive. Many of the cancer patients and some of the CORD patients gave positive responses, whilst exposed worker groups did not show statistically significant increases by comparison with the co ntrols. Thus, an increase in ras oncoproteins could be a biomarker for canc er or the disease state in general, but it cannot be ruled out that it is a biomarker for exposure since many of the individuals examined were smokers exposed to cigarette smoke.