Increased TGFbeta1 plasma level in patients with lung cancer: potential mechanisms.

Abstract

Plasma transforming growth factor beta1 (TGFbeta1) levels are elevated in patients with lung cancer. As TGFbeta1 is mainly found in platelets and as nonmalignant pulmonary diseases (NMPD) are frequently associated with lung cancer, we investigated the potential contribution of platelet degranulation and/or of a concomitant NMPD to the increased plasma levels of TGFbeta1 reported in patients with lung cancer. Blood samples were collected in duplicate from 30 healthy subjects, 14 patients suffering from NMPD and 37 patients with lung cancer. The platelet count was determined and the samples were processed to obtain plasma. One sample was collected in EDTA (EDTA plasma) and the other in a mixture inhibiting platelet degranulation (PIM plasma). TGFbeta1 concentrations and beta-thromboglobulin (betaTG) levels, an index of platelet degranulation, were measured in both plasma samples. TGFbeta1 and betaTG plasma levels measured in PIM plasma were lower than those obtained in EDTA plasma. With respect to PIM plasma, both TGFbeta1 and betaTG levels were higher in patients with lung cancer than those with NMPD and in healthy individuals. In patients with NMPD, only TGFbeta1 levels were increased as compared to healthy controls, betaTG levels being similar. Methods for collecting and processing blood samples are critical in determining reliable circulating TGFbeta1 levels. Increased TGFbeta1 plasma levels observed in patients with lung cancer are related, at least partly, to concomitant NMPD and also to platelet degranulation as proved by increased betaTG levels.