Copper depletion inhibits CoCl2-induced aggressive phenotype of MCF-7 cells via downregulation of HIF-1 and inhibition of Snail/Twist-mediated epithelial-mesenchymal transition

Abstract

Copper, a strictly regulated trace element, is essential for many physiological processes including angiogenesis. Dysregulated angiogenesis has been associated with increased copper in tumors, and thus copper chelators have been used to inhibit tumor angiogenesis. However, it remains unclear whether copper has any effect on epithelial-mesenchymal transition (EMT). Using CoCl2-induced EMT of human breast carcinoma MCF-7 cells, we found that TEPA, a copper chelator, inhibited EMT-like cell morphology and cytoskeleton arrangement triggered by CoCl2; decreased the expression of vimentin and fibronectin, markers typical of EMT; inhibited HIF-1 activation and HIF1-α accumulation in nuclear; and down-regulated the expression of hypoxia-associated transcription factors, Snail and Twist1. Moreover, knockdown copper transport protein, Ctr1, also inhibited CoCl2-induced EMT and reversed the mesenchymal phenotype. In EMT6 xenograft mouse models, TEPA administration inhibited the tumor growth and increased mice survival. Immunohistochemical analysis of the xenograft further demonstrated that TEPA administration significantly inhibited tumor angiogenesis, down-regulated hypoxia-induced transcription factors, Snail and Twist1, leading to decreased transactivation of EMT-associated marker genes, vimentin and fibronectin. These results indicate that TEPA inhibits CoCl2-induced EMT most likely via HIF1-α-Snail/Twist signaling pathway, and copper depletion may be exploited as a therapeutic for breast cancer.

Influencing the Tumor Microenvironment: A Phase II Study of Copper Depletion Using Tetrathiomolybdate in Patients with Breast Cancer at High Risk for Recurrence and in Preclinical Models of Lung Metastases

“…Copper depletion may also reverse epithelial-mesenchymal transition (EMT) and downregulate expression of EMT-related genes, such as vimentin and fibronectin (16). Furthermore, copper is a key component of several enzymes critical to remodeling the tumor microenvironment and lung premetastatic niche, including lysyl oxidase (LOX), superoxide dismutase-1, and vascular adhesion protein-1 (17)(18)(19)(20)(21).…”

Gold nanoparticles attenuate metastasis by tumor vasculature normalization and epithelial–mesenchymal transition inhibition

“…Other studies have also shown that hypoxia and hypoxia-inducible factor-1 alpha (HIF-1α) promote EMT in several tumor types. [34][35][36] In our study, treatment with AuNPs induced tumor vasculature normalization and decreased hypoxia in tumor sections. These normalized vessels may limit the risk of tumor cells metastasis through blood circulation, and the improvement in oxygenation may subsequently result in a reduction in EMT.…”

CoCl2 increases the expression of hypoxic markers HIF‑1α, VEGF and CXCR4 in breast cancer MCF‑7 cells

“…Cobalt ions are substrates of the iron-chelating enzymes; they can substitute for the iron ions of the oxygen sensor hemoglobin and combine with oxygen at high concentrations, leading to molecules entering the deoxidization phase (11). As has been documented in previous studies, treatment with CoCl 2 is able to mimic hypoxia (12). In the present study, different concentrations of CoCl 2 and MCR-7 breast cancer cells were cultured together in vitro to find the optimal hypoxia model.…”