Hypoxic Cancer Secretome Induces A Proliferative Phenotype In Adjacent Cells

STEFANINI A. ¹ , POLACHINI G. ¹ , TAJARA E. ¹ , DA CUNHA B. ¹

Over the past years, it has become evident that cancer initiation and progression depends on several components of the tumor microenvironment, including inflammatory and immune cells, fibroblasts, endothelial cells, adipocytes, and extracellular matrix. These components of the tumor microenvironment and the neoplastic cells interact with each other providing pro and antitumor signals. The present study aimed to analyze tumor-microenvironment interactions and their effects on the secretome of cancer cells. For this purpose, two cell lines from head and neck carcinomas were cultured in hypoxia conditions. The medium conditioned by these cells (secretome 1) and their control cells were used to grow untreated normal human fibroblasts from oral cavity. The peptides from these fibroblasts and their secretome (secretome 2) were analyzed by LTQ Orbitrap Velos mass spectrometer coupled to the nanoACQUITY Ultra Performance liquid chromatography system. For protein identification, the data were searched using MASCOT v.2.0. The results were loaded in Scaffold Q+ and quantitative data were compared using Student's t-test. Differences in expression were considered significant if the probability of error was p<0.05. Proteomics analysis of fibroblasts and their secretome allowed identification of 45 and 19 differentially expressed proteins, respectively. Most proteins of secretome 2 have been related to extracellular matrix organization, and others are involved in cell proliferation and migration, MAPK cascade, fibroblast growth factor receptor signaling pathway and response to hypoxia. Similarly, cellular proteins with a high expression levels in fibroblasts have been associated with response to hypoxia and to oxidative stress, differentiation, growth, proliferation, inflammation, angiogenesis, invasion, metastasis, extracellular matrix organization and negative regulation of apoptotic process. Our results suggest that signals derived from cancer cells in response to hypoxia drive the protein expression of adjacent cells. Financial support: FAPESP, CNPq.