Breast Tumor Cell Invasion and Pro-Invasive Activity of Cancer-Associated Fibroblasts Co-Targeted by Novel Urokinase-Derived Decapeptides.

Stefania Belli,Maria Patrizia Stoppelli,Paola Franco,Diego Brancaccio,Francesca Iommelli,Francesco Merlino,Marialucia Telesca,Anna De Vincenzo,Marie Ranson,Paolo Grieco,Alfonso Carotenuto,Silvana Del Vecchio,Ettore Novellino

doi:10.3390/cancers12092404

Abstract

Among peritumoral cells, cancer-associated fibroblasts (CAFs) are major facilitators of tumor progression. This study describes the effects of two urokinase-derived, novel decapeptides, denoted as Pep 1 and its cyclic derivative Pep 2. In a mouse model of tumor dissemination, using HT1080 fibrosarcoma cells, Pep 2 reduced the number and size of lung metastases. Specific binding of fluoresceinated Pep 2 to HT1080 and telomerase immortalised fibroblasts (TIF) cell surfaces was enhanced by αv overexpression or abolished by excess vitronectin, anti-αv antibodies or silencing of ITGAV αv gene, identifying αv-integrin as the Pep 2 molecular target. In 3D-organotypic assays, peptide-exposed TIFs and primary CAFs from breast carcinoma patients both exhibited a markedly reduced pro-invasive ability of either HT1080 fibrosarcoma or MDA-MB-231 mammary carcinoma cells, respectively. Furthermore, TIFs, either exposed to Pep 2, or silenced for αv integrin, were impaired in their ability to chemoattract cancer cells and to contract collagen matrices, exhibiting reduced α-smooth muscle actin (α-SMA) levels. Finally, peptide exposure of αv-expressing primary CAFs led to the downregulation of α-SMA protein and to a dramatic reduction of their pro-invasive capability. In conclusion, the ability of the novel decapeptides to interfere with tumor cell invasion directly and through the down-modulation of CAF phenotype suggests their use as lead compounds for co-targeting anti-cancer strategies.

Highlights

In the past solid tumors were regarded as relatively homogeneous groups of hyperproliferating cells with the ability to invade neighboring tissues and, possibly, metastasize
We show that the two novel decapeptides, based on these characteristics, denoted as Pep 1 and Pep 2 (Table 1) prevented mouse lung metastases
These findings show that either treatment with both decapeptides or αv-silencing reduce the secretion of motogen factors and impair the matrix contractile ability of telomerase immortalised fibroblasts (TIF) fibroblasts

Summary

Introduction

In the past solid tumors were regarded as relatively homogeneous groups of hyperproliferating cells with the ability to invade neighboring tissues and, possibly, metastasize. Intensive studies on solid mammary, lung, intestinal and prostatic cancer have described a surrounding tumor microenvironment (TME), that includes infiltrated immune cells (T cells and macrophages), endothelial cells, pericytes, adipocytes and cancer-associated fibroblasts (CAFs). Tissue fibroblasts are characterised by negligible transcriptional and metabolic activity, they may be activated during tumorigenesis, and acquire a wide spectrum of new abilities that sustain the establishment of solid tumors. Recruitment and activation of peritumoral fibroblasts are mediated by growth factors secreted by cancer epithelial and by several TME cell types, such as transforming growth factor-β (TGF-β), platelets-derived growth factor (PDGF) and fibroblast growth factor-2 (FGF-2) [5]. Recent evidence highlights the relevance of IGF-1 and IGF-2 (Insulin-like growth factors 1 and 2), secreted by mammary tumor epithelial cells and inducing the recruitment and activation of patient-derived primary CAFs through the IGF-1R [6]

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Results

Discussion

Conclusion