c-Met Ectodomain Shedding Rate Correlates with Malignant Potential

Abstract

Purpose: Many proteins are proteolytically released from the cell surface by a process known as ectodomain shedding. Shedding occurs under normal physiologic conditions and can be increased in certain pathologies. Among the many receptors for which ectodomain shedding has been shown is c-Met, the hepatocyte growth factor (HGF) receptor tyrosine kinase. HGF stimulates mitogenesis, motogenesis, and morphogenesis in a variety of cellular targets during development, homeostasis, and tissue regeneration. Inappropriate HGF signaling resulting in unregulated cell proliferation, motility, and invasion occurs in several human malignancies. This can occur through paracrine signaling, autocrine loop formation, receptor mutation, gene amplification, or gene rearrangement, accompanied frequently with overexpression of ligand and/or receptor proteins.We hypothesized that c-Met overexpression in cancer might result in increased ectodomain shedding, and that its measure could be a useful biomarker of tumor progression. Experimental Design: We developed a sensitive electrochemiluminescent immunoassay to quantitate c-Met protein in cell lysates, culture supernatants, and biological samples. Results: A survey of cultured cell models of oncogenic transformation revealed significant direct correlations (P < 0.001, t test orANOVA) between malignant potential and the rate of c-Met ectodomain shedding that was independent of steady-state receptor expression level. Moreover, weekly plasma and urine samples from mice harboring s.c. human tumor xenografts (n = 4 per group) displayed soluble human c-Met levels that were measurable before tumors became palpable and that correlated directly with tumor volume (R 2 > 0.92, linear regression).Conclusions: For a variety of human cancers, c-Met ectodomain shedding may provide a reliable and practical indicator of malignant potential and overall tumor burden.

In-depth Proteomic Analysis of Six Types of Exudative Pleural Effusions for Nonsmall Cell Lung Cancer Biomarker Discovery

“…The authors concluded that a high MET expression led to an increased potential for tumor metastasis and consequently a poor prognosis (47). These phenomena were similar to those shown in a breast cancer study in which MET shedding correlated with malignancy in cultured cells and tumor burden in tumor xenograft mouse models (48). Conversely, Yang et al demonstrated the beneficial effects of high sMET concentrations in human plasma, showing that the overall median plasma concentration of sMET in patients with gastric cancer was lower than in controls, and sMET levels decreased as the onset of cancer drew nearer (49).…”

Nonclinical Evaluation of the Serum Pharmacodynamic Biomarkers HGF and Shed MET following Dosing with the Anti-MET Monovalent Monoclonal Antibody Onartuzumab

“…33,35). Levels of sMET in blood and urine correlated with size and malignant potential of human tumors in xenograft mouse models and in patients (33,(35)(36)(37). Antibody targeting of MET with the bivalent anti-MET antibody DN-30 induced cleavage of the MET ECD, followed by downregulation and proteolytic degradation of the carboxy-terminal fragment (30,31,38,39).…”

Synergistic Signaling of Tumor Cell Invasiveness by Hepatocyte Growth Factor and Hypoxia

“…Membranes were washed three times with TBST, incubated with horseradish peroxidase-labeled secondary antibody for 1 h at 25°C, and washed for 3 h with TBS prior to ECL detection (Pierce). Phosphorylated and total Met contents in Triton X-100 cell extracts were determined by an electrochemiluminescent immunoassay read using a SectorImager 2400 (Meso Scale Discovery, Gaithersburg, MD) as described previously (18).…”