Data from Id1-Induced IGF-II and Its Autocrine/Endocrine Promotion of Esophageal Cancer Progression and Chemoresistance—Implications for IGF-II and IGF-IR–Targeted Therapy

Purpose: To investigate the autocrine/endocrine role of Id1-induced insulin-like growth factor-II (IGF-II) in esophageal cancer, and evaluate the potential of IGF-II- and IGF-type I receptor (IGF-IR)-targeted therapies.Experimental Design: Antibody array-based screening was used to identify differentially secreted growth factors from Id1-overexpressing esophageal cancer cells. In vitro and in vivo assays were performed to confirm the induction of IGF-II by Id1, and to study the autocrine and endocrine effects of IGF-II in promoting esophageal cancer progression. Human esophageal cancer tissue microarray was analyzed for overexpression of IGF-II and its correlation with that of Id1 and phosphorylated AKT (p-AKT). The efficacy of intratumorally injected IGF-II antibody and intraperitoneally injected cixutumumab (fully human monoclonal IGF-IR antibody) was evaluated using in vivo tumor xenograft and experimental metastasis models.Results: Id1 overexpression induced IGF-II secretion, which promoted cancer cell proliferation, survival, and invasion by activating AKT in an autocrine manner. Overexpression of IGF-II was found in 21 of 35 (60%) esophageal cancer tissues and was associated with upregulation of Id1 and p-AKT. IGF-II secreted by Id1-overexpressing esophageal cancer xenograft could instigate the growth of distant esophageal tumors, as well as promote metastasis of circulating cancer cells. Targeting IGF-II and IGF-IR had significant suppressive effects on tumor growth and metastasis in mice. Cixutumumab treatment enhanced the chemosensitivity of tumor xenografts to fluorouracil and cisplatin.Conclusions: The Id1–IGF-II–IGF-IR–AKT signaling cascade plays an important role in esophageal cancer progression. Blockade of IGF-II/IGF-IR signaling has therapeutic potential in the management of esophageal cancer. Clin Cancer Res; 20(10); 2651–62. ©2014 AACR.