Tumor microenvironment triggers photodynamic resistance through fibroblast population by HIF-1 pathway modulation

LAMBERTI MJ; KRIJGSVELD J; RUMIE VITTAR NB; RIVAROLA VA

Congreso; SAIC; 2016

The study of the tumor microenvironment (TME) has given rise to the concept that tumor progression is dependent on a network of interactions among cancer cells and the surrounding stroma. One of the most important aspects of the TME crosstalk is the ability of cancer cells to modulate stroma behavior, and vice versa, through the collective action of a variety of soluble mediators. In this sense, we aimed to identify soluble factors present in the TME putatively linked to cancer-relevant pathways by performing a high-throughput secretome profiling. To mimic TME heterogeneity and architecture, we co-cultured colorectal (CRC) tumor cells (SW480, TC) with stromal fibroblasts cells (MRC-5, FC) as 3D-spheroids. The characterization of the homotypic (TC) and heterotypic (TC+FC) spheroids´ secretomes was performed using label-free LC?MS. Bioinformatic analysis using PID database revealed that HIF-1 signaling pathway was the most highly enriched within the proteins whose secretion was enhanced in heterotypic spheroids. In a previous report, we demonstrated that HIF-1 was strongly associated with CRC-resistance to photodynamic therapy (PDT), an antitumor therapeutic that combines photosensitizing agents, O2 and light to create a harmful photochemical reaction. Consistently, the presence of FC considerably diminished TC sensitivity to photodynamic activity (MTT). In addition, despite the biological significance of the HIF-1 pathway of secretomes was reduced after photosensitization, this decreased was partially reversed in heterotypic 3D-cultures. HIF-1 pathway modulation by both PDT and FC was further confirmed through the evaluation of the expression of the HIF-target gene VEGF (RT-qPCR). Collectively, these results delineate a mechanism by which FC enhance TC survival and treatment resistance, which can potentially guide translational research specifically aimed at effective clinical interventions for fibroblast-enriched and consequently HIF-1 pathway overexpressing tumors