Purpose: Cancer-associated fibroblasts (CAF) actively participate in reciprocal communication with tumor cells and with other cell types in the microenvironment, contributing to a tumor-permissive neighborhood and promoting tumor progression. The aim of this study is the characterization of how CAFs from primary human colon tumors promote migration of colon cancer cells. Experimental design: Primary CAF cultures from 15 primary human colon tumors were established. Their enrichment in CAFs was evaluated by the expression of various epithelial and myofibroblast specific markers. Coculture assays of primary CAFs with different colon tumor cells were performed to evaluate promigratory CAF-derived effects on cancer cells. Gene expression profiles were developed to further investigate CAF characteristics. Results: Coculture assays showed significant differences in fibroblast-derived paracrine promigratory effects on cancer cells. Moreover, the association between CAFs' promigratory effects on cancer cells and classic fibroblast activation or stemness markers was observed. CAF gene expression profiles were analyzed by microarray to identify deregulated genes in different promigratory CAFs. The gene expression signature, derived from the most protumorogenic CAFs, was identified. Interestingly, this “CAF signature” showed a remarkable prognostic value for the clinical outcome of patients with colon cancer. Moreover, this prognostic value was validated in an independent series of 142 patients with colon cancer, by quantitative real-time PCR (qRT-PCR), with a set of four genes included in the “CAF signature.” Conclusions: In summary, these studies show for the first time the heterogeneity of primary CAFs' effect on colon cancer cell migration. A CAF gene expression signature able to classify patients with colon cancer into high- and low-risk groups was identified. Clin Cancer Res; 19(21); 5914–26. ©2013 AACR.

Peritoneal adhesions (PAs) are fibrotic bands formed between bowel loops, solid organs, and the parietal peritoneum, which may appear following surgery, infection or endometriosis. They represent an important health problem with no effective treatment. Mesothelial cells (MCs) line the peritoneal cavity and undergo a mesothelial-to-mesenchymal transition (MMT) under pathological conditions, transforming into myofibroblasts, which are abundant in peritoneal fibrotic tissue. The aim of this study was to investigate if peritoneal MCs undergo a MMT contributing to the formation of post-surgical adhesions. Biopsies from patients with PAs were analysed by immunohistochemistry, immunofluorescence, and quantitative RT-PCR. A mouse model of PAs based on ischaemic buttons was used to modulate MMT by blocking the transforming growth factor-beta (TGF-β) pathway. The severity of adhesions and MMT-related marker expression were studied. We observed myofibroblasts derived from the conversion of MCs in submesothelial areas of patients with PAs. In addition, MMT-related markers were dysregulated in adhesion zones when compared to distant normal peritoneal tissue of the same patient. In animal experiments, blockage of TGF-β resulted in molecular reprogramming of markers related to the mesenchymal conversion of MCs and in a significant decrease in the severity of the adhesions. These data indicate for the first time that MMT is involved in PA pathogenesis. This finding opens new therapeutic strategies to interfere with adhesion formation by modulating MMT with a wide range of pharmacological agents.

Tumor-derived exosomes are emerging as local and systemic cell-to-cell mediators of oncogenic information through the horizontal transfer of mRNAs, microRNAs and proteins during tumorigenesis. The exosomal content has been described as biologically active when taken up by the recipient cell. Identifying the specific molecular cargo of exosomes will help to determine their function in specific steps of the tumorigenic process. Here we evaluate whether ΔNp73 is selectively packaged in tumor-derived exosomes, its function in the acceptor cells in vitro and in vivo and its prognosis potential in cancer. ΔNp73 messenger is enriched in tumor-derived exosomes, suggesting its active sorting in these microvesicles. We observed the transmission of this exosome cargo to different cell types and how it confers proliferation potential and chemoresistance to the acceptor cells in vitro and in animal models. Finally, our data support the potential prognostic value of exosomal ΔNp73 in colon cancer patients.