ARTICLE ABSTRACT
The causes for malignant progression of disseminated tumors and the reasons recurrence rates differ in women with different breast cancer subtypes are unknown. Here, we report novel mechanisms of tumor plasticity that are mandated by microenvironmental factors and show that recurrence rates are not strictly due to cell-intrinsic properties. Specifically, outgrowth of the same population of incipient tumors is accelerated in mice with triple-negative breast cancer (TNBC) relative to those with luminal breast cancer. Systemic signals provided by overt TNBCs cause the formation of a tumor-supportive microenvironment enriched for EGF and insulin-like growth factor-I (IGF-I) at distant indolent tumor sites. Bioavailability of EGF and IGF-I enhances the expression of transcription factors associated with pluripotency, proliferation, and epithelial–mesenchymal transition. Combinatorial therapy with EGF receptor and IGF-I receptor inhibitors prevents malignant progression. These results suggest that plasticity and recurrence rates can be dictated by host systemic factors and offer novel therapeutic potential for patients with TNBC.Significance: Currently, processes that mediate progression of otherwise indolent tumors are not well understood, making it difficult to accurately predict which patients with cancer are likely to relapse. Our findings reveal novel mechanisms of tumor phenotypic and gene expression plasticity that are mandated by microenvironmental factors, identifying novel therapeutic targets for patients with TNBC. Cancer Discov; 3(8); 922–35. ©2013 AACR.This article is highlighted in the In This Issue feature, p. 826
