Growth control by epidermal growth factor and transforming growth factor-α in human lung squamous carcinoma cells

Abstract

Summary Although EGF receptor expression is generally elevated in human lung squamous carcinoma, the biological significance of this phenomenon and the role of EGF and TGF-a in this disease are poorly understood. We have investigated three human lung squamous carcinoma cell lines (NX002, CX140 and CX143) and have shown, using an antibody (EGFRI) directed against the EGF receptor, that the majority of cells in all three lines express the EGF receptor. Using a ligand binding assay, Scatchard analysis indicated high concentrations (1,300-2,700 fmol mg-' protein) of a single low affinity binding site (Kd = 3-5 nM) within these lines. Addition of EGF or TGF-a at concentrations greater than 0.1 nm resulted in growth inhibition of all three lines and this was associated with an accumulation of cells in the G2/M phase of the cell cycle. Growth inhibitory effects were not explained by an enhancement of cellular differentiation as monitored by involucrin expression and the ability to form cornified envelopes. While the presence of EGF could not be detected in medium conditioned by the NX002 cell line, mRNA for TGF-a was detected in all three lines suggesting the possibility of an autocrine loop. These results together with reports of growth inhibition by EGF and TGF-a in other systems suggest that EGF and similar molecules might have a growth regulatory role in lung cancer cells and modulation of such may have therapeutic potential.The related molecules, epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-ax), modulate the growth of a wide variety of normal and malignant cells (reviewed in Burgess et al., 1989). Both factors operate through the EGF receptor and in many malignant diseases, for example lung squamous carcinoma, levels of the EGF receptor are markedly overexpressed relative to normal tissue (Hendler & Ozanne, 1984;Cerny et al., 1986;Berger et al., 1987;Veale et al., 1987;Sobol et al., 1987;Dazzi et al., 1989). The biological significance of this overexpression of receptors in lung squamous carcinoma is not known. Cell lines derived from human lung squamous carcinoma cell lines have been shown to possess high concentrations of EGF receptors (Haeder et al., 1988) and represent useful models to study growth factor modulation. Little is known of the role of EGF and TGF-x in this disease, however, several reports have proposed that TGF-o may act in an autocrine manner in this cell type (Lee et al., 1990;Putnam et al., 1991) while another recent study has suggested that either EGF or TGFa might stimulate squamous differentiation (Levitt et al., 1991).In order to investigate further the role of EGF-like factors in lung squamous carcinoma cells, we have developed cell line models and have examined them for the presence of EGF receptors. Two approaches have been used to detect and measure the levels of this receptor: immunocytochemical staining using an antibody directed against the receptor and a competitive binding assay employing radiolabelled EGF. We have also studied the effects of EGF and T...

β-Hydroxyisovalerylshikonin and Cisplatin Act Synergistically to Inhibit Growth and to Induce Apoptosis of Human Lung Cancer DMS114 Cells via a Tyrosine Kinase-Dependent Pathway

“…Several receptors with tyrosine kinase activity appear to be expressed or overexpressed in lung cancer cells [21, 22, 23, 24, 25]. Interference with the activation of these receptor protein tyrosine kinases by antibodies against the receptors inhibits cell growth [26, 27].…”

Activation of Stat3 by receptor tyrosine kinases and cytokines regulates survival in human non-small cell carcinoma cells

“…First, tyrosine kinase growth factor receptors are overexpressed in a large number of human lung cancers, with non-small cell lung cancers demonstrating overexpression of EGF-R and its ligands EGF, amphiregulin, and TGF-alpha, while some small cell lung cancers demonstrate c-kit overexpression (Antoniades et al, 1992;Rusch et al, 1993Rusch et al, , 1997Takanami et al, 1995;Kawai et al, 1997;Krystal et al, 2000;Brabender et al, 2001). Lung cancer cell lines can produce soluble EGF or TGF-alpha and targeting the EGF-R with either monoclonal antibodies or small molecule inhibitors can lead to inhibition of tumor growth and in some cases tumor regression (Lee et al, 1992;Rabiasz et al, 1992;Lei et al, 1998Lei et al, , 1999Fang and Chen, 1999;Ciardiello et al, 2000;Sirotnak et al, 2000;Wang et al, 2000a;Norman, 2001). Second, Src, a major upstream regulator of STAT activity, has also been suggested to be activated in human lung cancers (Mazurenko et al, 1992;Budde et al, 1994).…”

The Jun Kinase 2 Isoform Is Preferentially Required for Epidermal Growth Factor-Induced Transformation of Human A549 Lung Carcinoma Cells

“…EGF is a very potent autocrine growth factor in human lung cancer (32,53,67,69,73,75,85,88) and is involved in cancer cell proliferation and tumorigenicity of human glioblastomas (26,46,62,92), breast cancer (1,25,27,58), and keratinocytes (33,69). Taken together, these data show that EGF and its receptor play significant roles in the genesis and/or progression of many human cancers (84).…”