CXCL8 Signaling in the Tumor Microenvironment.

The tumor microenvironment represents a dynamic and complex cellular network involving intricate communications between the tumor and highly heterogeneous groups of cells, including tumor-supporting immune and inflammatory cells, cancer-associated fibroblasts, endothelial cells, tumor-associated macrophages, adipose cells, and pericytes. Associated with a variety of growth factors, chemokines, cytokines, and other signaling molecules, the interaction between the tumor microenvironment and the tumor cells empowers aggressiveness of tumor by enhancing its survivability. CXCL8 (also known as Interleukin 8), a multifunctional proinflammatory chemokine that was initially classified as a neutrophil chemoattractant, recently has been found to be a key contributor in tumorigenesis. The upregulation of CXCL8 at the tumor invasion front in several human cancers suggests its interplay between the tumor and its microenvironment rendering tumor progression by enhancing angiogenesis, tumor genetic diversity, survival, proliferation, immune escape, metastasis, and multidrug resistance. The autocrine and paracrine modulation of CXCL8 via the chemokine receptors CXCR1/2 promotes several intracellular signaling cascades that fosters tumor-associated inflammation, reprogramming, epithelial-mesenchymal transition, and neovascularization. Hence, decrypting the regulatory/signaling cascades of CXCL8 and its downstream effects may harbor prognostic clinical prospects of a tumor microenvironment-oriented cancer therapeutics.