Growth-factor-dependent migration of human lung-cancer cells.

Human lung tumors express different types of growth-factor receptors and corresponding ligands that might modulate several biological functions such as proliferation, differentiation, adhesion, and chemotaxis. In the present study, we have investigated the expression of different growth-factor receptors and their ligands in 5 established human lung-cancer cell lines. Using RT-PCR, we found that IGF-II/mannose-6-phosphate (M6P), c-met, EGF and c-kit receptors are expressed in 5/5 human lung-cancer cell lines. In order to investigate the biological function of these receptors, we performed Boyden-chamber assays using various growth factors as chemo-attractants. Human non-small-cell-lung-cancer cells (non-SCLC) migrated to recombinant human (rh)IGF I and IGF II at concentrations ranging from 1 to 1000 ng/ml, to HGF at 10 to 100 ng/ml, to EGF at 1 to 100 ng/ml and SCF at 1 to 50 ng/ml. In addition, we performed Boyden-chamber assays using U-1810-, U-1752- and Wart-derived serum-free conditioned medium as chemo-attractants. Serum-free conditioned medium stimulated migration of producer cells in a dose-dependent manner. The autocrine motility stimulating effect of U-1810-derived serum-free conditioned medium could be inhibited by 50% in the presence of neutralizing ahIGF-II antibodies in the assay, suggesting a possible autocrine motility loop in vitro.

Integrin dependent migration of lung cancer cells to extracellular matrix components.

Since tumour progression is dependent on the ability of malignant cells to interact with the extracellular matrix (ECM), we have investigated the significance of beta1 and beta3 integrins for migration of lung cancer cells to components of the ECM. In an in vitro hapto- and chemotactic assay system, five cell lines representing the major types of lung cancer were examined: adenocarcinoma (WART); squamous cell carcinoma (U-1752); small cell lung cancer (SCLC) (U-1906, 054 A) and large cell lung cancer (LCLC) (U-1810). Flow cytometric analyses were performed to characterize their integrin expression. U-1906, 054 A, WART and U-1752 all expressed beta1 integrins whereas U-1810 did not. However, U-1810 and U-1752 expressed beta3 integrins. All cell lines except U-1810 and U-1752 showed hapto- and chemotactic motility to fibronectin, laminin and type IV collagen and this motility was beta1 integrin-dependent except in the case of U-1810. However, the hapto- and chemotactic responses differed markedly between the separate cell lines and there was no distinct pattern to separate non-small cell lung cancer (NSCLC) from SCLC. No or very little migration was seen in control experiments with bovine serum albumin (BSA) or serum-free medium alone, indicating that the migration of the lung cancer cells require adhesion molecules, soluble or substratum bound. We have found the involvement of beta1 integrins in lung cancer cell migration in vitro towards fibronectin, laminin and type IV collagen except in the case of U-1810. The U-1810 cell line clearly differed from the rest of the cell lines by lacking expression of beta1 integrins.