A Dominant Negative Type I Insulin-like Growth Factor Receptor Inhibits Metastasis of Human Cancer Cells

The opioid growth factor (OGF) regulates cell proliferation of human cancer cells through the cyclin-dependent kinase inhibitory pathway, with mediation of this action by the OGF receptor (OGFr). The ubiquity of the OGF-OGFr axis in human cancer is unknown. We used 31 human cancer cell lines, representative of more than 90% of neoplasias occurring in humans, and found that OGF and OGFr were detected in the cytoplasm and nucleus by immunohistochemistry. The addition of OGF to cultures depressed cell number up to 41%, whereas naltrexone (NTX) increased cell proliferation by up to 44%, a total of 85% in the modulating capacity for the OGF-OGFr axis. Neutralization of OGF by specific antibodies led to a marked increase in cell number. Knockdown of OGFr by OGFr-siRNA resulted in a significant increase in the number of cells, even in the face of the addition of exogenous OGF. The cultures to which NTX was added and subjected to OGFr-siRNA were similar to those with OGF-siRNA alone. The OGF-OGFr axis, a physiological determinant of cell-proliferative activity, is a ubiquitous feature of human cancer cells. The identification of this native biological system in neoplasia may be important in understanding the pathophysiology of neoplasia, and in designing treatment modalities that utilize the body's own chemistry.

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Dual Regulation of MMP-2 Expression by the Type 1 Insulin-like Growth Factor Receptor

Journal of Biological Chemistry ◽

10.1074/jbc.m313145200 ◽

2004 ◽

Vol 279 (19) ◽

pp. 19683-19690 ◽

Cited By ~ 122

Author(s):

Donglei Zhang ◽

Menashe Bar-Eli ◽

Sylvain Meloche ◽

Pnina Brodt

Keyword(s):

Protein Synthesis ◽

Growth Factor ◽

Kinase Inhibitors ◽

Growth Factor Receptor ◽

Signal Transduction Pathway ◽

Dominant Negative ◽

Type I ◽

Insulin Like Growth Factor ◽

Igf I ◽

In Cells

The matrix metalloproteinase (MMP)-2 has been recognized as a major mediator of basement membrane degradation, angiogenesis, tumor invasion, and metastasis. The factors that regulate its expression have not, however, been fully elucidated. We previously identified the type I insulin-like growth factor (IGF-I) receptor as a regulator of MMP-2 synthesis. The objective of the present study was to investigate the signal transduction pathway(s) mediating this regulation. We show here that in Lewis lung carcinoma subline H-59 cells treated with IGF-I (10 ng/ml), the PI 3-kinase (phosphatidylinositol 3′-kinase) /protein kinase B (Akt) and C-Raf/ERK pathways were activated, andMMP-2promoter activity, mRNA, and protein synthesis were induced. MMP-2 induction was blocked by the PI 3-kinase inhibitors LY294002 and wortmannin, by overexpression of a dominant-negative Akt or wild-type PTEN (phosphatase and tensin homologue deleted on chromosome 10), and by rapamycin. In contrast, a MEK inhibitor PD98059 failed to reduceMMP-2promoter activation and actually increasedMMP-2mRNA and protein synthesis by up to 30%. Interestingly, suppression of PI 3-kinase signaling by a dominant-negative Akt enhanced ERK activity in cells stimulated with 10 ng/ml but not with 100 ng/ml IGF-I. Furthermore, at the higher (100 ng/ml) IGF-I concentration, C-Raf and ERK, but not PI 3-kinase activation, was enhanced, and this resulted in down-regulation of MMP-2 synthesis. This effect was reversed in cells expressing a dominant-negative ERK mutant. The results suggest that IGF-I can up-regulate MMP-2 synthesis via PI 3-kinase/Akt/mTOR (the mammalian target of rapamycin) signaling while concomitantly transmitting a negative regulatory signal via the Raf/ERK pathway. The outcome of IGF-IR (the receptor for IGF-I) activation may ultimately depend on factors, such as ligand bioavailability, that can shift the balance preferentially toward one pathway or the other.

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EGFR signal transactivation in cancer cells

Biochemical Society Transactions ◽

10.1042/bst0311203 ◽

2003 ◽

Vol 31 (6) ◽

pp. 1203-1208 ◽

Cited By ~ 284

Author(s):

O.M. Fischer ◽

S. Hart ◽

A. Gschwind ◽

A. Ullrich

Keyword(s):

Growth Factor ◽

Cancer Cells ◽

Cross Talk ◽

Molecular Mechanisms ◽

Human Cancer ◽

Growth Factor Receptor ◽

Cell Types ◽

General Concept ◽

Human Carcinoma ◽

Human Cancer Cells

The EGFR (epidermal growth factor receptor) plays a key role in the regulation of essential normal cellular processes and in the pathophysiology of hyperproliferative diseases such as cancer. Recent investigations have demonstrated that GPCRs (G-protein-coupled receptors) are able to utilize the EGFR as a downstream signalling partner in the generation of mitogenic signals. This cross-talk mechanism combines the broad diversity of GPCRs with the signalling capacities of the EGFR and has emerged as a general concept in a multitude of cell types. The molecular mechanisms of EGFR signal transactivation involve processing of transmembrane growth factor precursors by metalloproteases which have been recently identified as members of the ADAM (adisintegrin and metalloprotease) family of zinc-dependent proteases. Subsequently, the EGFR transmits signals to prominent downstream pathways, such as mitogen-activated protein kinases, the phosphoinositide 3-kinase/Akt pathway and modulation of ion channels. Analysis of GPCR-induced EGFR activation in more than 60 human carcinoma cell lines derived from different tissues has demonstrated the broad relevance of this signalling mechanism in cancer. Moreover, EGFR signal transactivation was linked to diverse biological processes in human cancer cells, such as cell proliferation, migration and anti-apoptosis. Together with investigations revealing the importance of this GPCR–EGFR cross-talk mechanism in cardiac hypertrophy, Helicobacter pylori-induced pathophysiological processes and cystic fibrosis, these findings support an important role for GPCR ligand-dependent EGFR signal transactivation in diverse pathophysiological disorders.

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