The monoclonal antibody Zt/f2 targeting RON receptor tyrosine kinase as potential therapeutics against tumor growth-mediated by colon cancer cells

Abstract

BackgroundOverexpression of the RON receptor tyrosine kinase contributes to epithelial cell transformation, malignant progression, and acquired drug resistance. RON also has been considered as a potential target for therapeutic intervention. This study determines biochemical features and inhibitory activity of a mouse monoclonal antibody (mAb) Zt/f2 in experimental cancer therapy.ResultsZt/f2 is a mouse IgG2a mAb that is highly specific and sensitive to human RON and its oncogenic variants such as RON160 (ED50 = 2.3 nmol/L). Receptor binding studies revealed that Zt/f2 interacts with an epitope(s) located in a 49 amino acid sequence coded by exon 11 in the RON β-chain extracellular sequences. This sequence is critical in regulating RON maturation and phosphorylation. Zt/f2 did not compete with ligand macrophage-stimulating protein for binding to RON; however, its engagement effectively induced RON internalization, which diminishes RON expression and impairs downstream signaling activation. These biochemical features provide the cellular basis for the use of Zt/f2 to inhibit tumor growth in animal model. Repeated administration of Zt/f2 as a single agent into Balb/c mice results in partial inhibition of tumor growth caused by transformed NIH-3T3 cells expressing oncogenic RON160. Colon cancer HT-29 cell-mediated tumor growth in athymic nude mice also was attenuated following Zt/f2 treatment. In both cases, ~50% inhibition of tumor growth as measured by tumor volume was achieved. Moreover, Zt/f2 in combination with 5-fluorouracil showed an enhanced inhibition effect of ~80% on HT-29 cell-mediated tumor growth in vivo.ConclusionsZt/f2 is a potential therapeutic mAb capable of inhibiting RON-mediated oncogenesis by colon cancer cells in animal models. The inhibitory effect of Zt/f2 in vivo in combination with chemoagent 5-fluorouracil could represent a novel strategy for future colon cancer therapy.

Synergistic Activities of MET/RON Inhibitor BMS-777607 and mTOR Inhibitor AZD8055 to Polyploid Cells Derived from Pancreatic Cancer and Cancer Stem Cells

“…Various studies have shown that therapeutic antibodies and TKIs specific to RON inhibit tumor growth mediated by pancreatic, colon, and breast cancer cells in mouse tumor xenograft models (7,12,13,31). Studies using BMS-777607 to target MET have shown the effectiveness in inhibiting MET-mediated tumor cell migration, matrix invasion, and distance metastasis (32,33).…”

RON - The Con in Colorectal Carcinoma

“…Further treatment with neutralizing mAbs in addition to down regulating RON-β chain expression also inhibits the expression of pro-RON. It was observed that treatment with Zt/f2 causes tumor regression in as early as five days of administration in xenograft mouse model [60]. An in vitro assay shows that although the antibody induces the phosphorylation of RON receptor initially it subsequently leads to receptor internalization and thus favourable biological outcomes.…”

“…The prospect of clinically targeting RON is currently being explored by the two main strategies -the development of neutralizing monoclonal antibodies and use of small molecule kinase inhibitors. The monoclonal antibodies (mAb) used to study the effect of blocking RON signaling pathways in CRC include Zt/f2, Zt/g4, Zt/c9 and Zt/c1 and act by inducing receptor internalization followed by protein degradation [58][59][60]. Zt/g4 and Zt/c9 both recognize epitopes on the sema sequence while Zt/f2 binds with epitopes on the IPT domain.…”

Small-Molecule Inhibitor BMS-777607 Induces Breast Cancer Cell Polyploidy with Increased Resistance to Cytotoxic Chemotherapy Agents

“…These observations provide the rationale for targeting RON as a potential cancer therapy (13,14). At present, inhibition of RON by therapeutic monoclonal antibodies (mAb) and small-molecule inhibitors (SMI) has been studied in preclinical models (10,(15)(16)(17). Partial inhibition of tumor growth in animal xenograft models has been observed (10,(15)(16)(17).…”

“…At present, inhibition of RON by therapeutic monoclonal antibodies (mAb) and small-molecule inhibitors (SMI) has been studied in preclinical models (10,(15)(16)(17). Partial inhibition of tumor growth in animal xenograft models has been observed (10,(15)(16)(17). Further inhibition is achieved by RON-targeted mAb or SMI in combination with chemotherapeutic agents (15).…”