Document Type

Article

Publication Date

6-27-2017

Comments

This article has been peer reviewed. It is the author’s final published version in Oncotarget

Volume 8, Issue 26, June 2017, Pages 43248-43270.

The published version is available at DOI: 10.18632/oncotarget.18020. Copyright © Vella et al.

Abstract

The fetal isoform A of the insulin receptor (IR-A) is frequently overexpressed in a variety of malignancies including breast cancer. IR overexpression has a recognized role in cancer progression and resistance to anticancer therapies. In particular, IR-A has a peculiar mitogenic potential and is activated not only by insulin but also by IGF-2. Previously, we identified discoidin domain receptor 1 (DDR1) as a new IR-A interacting protein. DDR1, a non-integrin collagen tyrosine kinase receptor, is overexpressed in several malignancies and plays a role in cancer progression and metastasis.We now evaluated whether DDR1 is able to exert a role in breast cancer biology by functionally cross-talking with IR. In MCF-7 human breast cancer cells, IR and DDR1 co-immunoprecipitated and co-localized after insulin or IGF-2 stimulation. In a panel of breast cancer cells, DDR1 knockdown by specific siRNAs markedly inhibited IR downstream signaling as well as proliferation, migration and colony formation in response to insulin and IGF-2. These effects were accompanied by reduction of IR protein and mRNA expression, which involved both transcriptional and post-transcriptional effects. DDR1 overexpression elicited opposite effects. Bioinformatics analysis of public domain databases showed that IR and DDR1 co-expression significantly correlates with several clinically relevant histopathological and molecular features of human breast carcinomas.These findings demonstrate that, in human breast cancer cells, DDR1 regulates IR expression and ligand dependent biological actions. This novel functional crosstalk is likely clinically relevant and may become a new molecular target in breast cancer.

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