Nerve Growth Factor Stimulates Proliferation and Survival of Human Breast Cancer Cells through Two Distinct Signaling Pathways

Abstract

We show here that the neurotrophin nerve growth factor (NGF), which has been shown to be a mitogen for breast cancer cells, also stimulates cell survival through a distinct signaling pathway. Breast cancer cell lines (MCF-7, T47-D, BT-20, and MDA-MB-231) were found to express both types of NGF receptors: p140 trkA and p75 NTR . The two other tyrosine kinase receptors for neurotrophins, TrkB and TrkC, were not expressed. The mitogenic effect of NGF on breast cancer cells required the tyrosine kinase activity of p140 trkA as well as the mitogen-activated protein kinase (MAPK) cascade, but was independent of p75 NTR . In contrast, the anti-apoptotic effect of NGF (studied using the ceramide analogue C2) required p75 NTR as well as the activation of the transcription factor NF-kB, but neither p140 trkA nor MAPK was necessary. Other neurotrophins (BDNF, NT-3, NT-4/5) also induced cell survival, although not proliferation, emphasizing the importance of p75 NTR in NGF-mediated survival. Both the pharmacological NF-B inhibitor SN50, and cell transfection with IkBm, resulted in a diminution of NGF anti-apoptotic effect. These data show that two distinct signaling pathways are required for NGF activity and confirm the roles played by p75 NTR and NF-B in the activation of the survival pathway in breast cancer cells. Nerve growth factor (NGF)1 is the archetypal member of the neurotrophin superfamily, which also includes brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), NT-4/5, and NT-6 (1). NGF interacts with two classes of membrane receptor: the TrkA proto-oncogene product p140 trkA , which possesses intrinsic tyrosine kinase activity, and a secondary receptor, p75 NTR , that belongs to the tumor necrosis factor (TNF) receptor family (2). The stimulation of cell survival and cell differentiation by NGF and other neurotrophins have been described primarily in neuronal cell systems (3). Although the neurotrophic effect through p140trkA is known to involve the MAPK cascade, the role of p75 NTR is still controversial; there is evidence that it can both positively and negatively regulate neuronal cell death and differentiation, depending on the cell type examined (4). In some cases, p75NTR is an inducer of apoptosis, even without NGF stimulation (5), whereas in other cases the activation of p75 NTR by NGF results in a protection from cell death (6). In addition to its neurotrophic function, other activities of NGF have been described. For example, NGF can modulate gene expression in monocytes (7), it is chemotactic for melanocytes (8), and its inhibition on p75 NTR can block the migration of Schwann cells (9). NGF also stimulates the proliferation of chromaffin cells (10), lymphocytes (11), and keratinocytes (12). We have previously shown that NGF is mitogenic for cancerous but not normal human breast cells (13), and these data, as well as others showing a role for NGF in the stimulation of prostatic cancer cells (14 -17), implicate NGF in non-neuronal carcinogenesis.Both cellular proliferation as well as tumor c...

Significance of nerve growth factor overexpression and its autocrine loop in oesophageal squamous cell carcinoma

“…For phosphorylated TrkA, a mouse monoclonal anti-p-TrkA antibody (sc-8058, Santa Cruz Biotechnology Inc.) (diluted 1 : 200) was used. Lysate from the breast cancer cell line MCF-7 was used as a positive control for NGF (Dolle et al, 2003), TrkA, and p75NTR (Descamps et al, 2001b).…”

Distribution and significance of nerve growth factor receptor (NGFR/p75NTR) in normal, benign and malignant breast tissue

“…14 However, the ratio between NGF:NGFR was reported to be of prognostic significance. 15 As the role of NGFR in breast cancer development and progression is not fully understood and conflicting results have been reported, [14][15][16][17] we decided to investigate the distribution of NGFR in breast tissue from various benign and malignant conditions and explore potential prognostic relationships. In a preliminary analysis, we and others 5 observed that NGFR showed a peculiar distribution, being restricted to myoepithelial cells, intralobular fibroblasts of terminal duct-lobular units, perivascular cells (vascular adventitia) and nerve bundles.…”

Epigenetic Inactivation and Tumor-Suppressor Behavior of NGFR in Human Colorectal Cancer

“…p75NGFR is a member of the TNFR superfamily and has been shown to be a conditional tumor-suppressor gene (19). In breast cancer and melanoma, p75NGFR acts as an oncogene, increasing cell proliferation, survival, and migration (6,(20)(21)(22). In contrast, in prostate cancer and neuroblastoma, p75NGFR acts as a tumor-suppressor gene, inducing apoptosis and inhibiting cell proliferation and invasion (23)(24)(25)(26)(27).…”