Participação da quimiocina CCL3 e seus receptores CCR1 e CCR5 e do receptor atípico ACKR2 na carcinogênese bucal

Abstract

Chemokines and chemokine receptors have assumed relevance in the context of oral carcinogenesis due to its potential activation of “pro-tumorigenic” pathways. The expression of CCL3 and its receptors (CCR1 and CCR5) have been demonstrated in oral squamous cell carcinoma (OSCC), however, their roles were not defined yet. In this study, the roles of CCL3/CCR1/CCR5 axis in chemically-induced oral carcinogenesis were evaluated in genetically-deficient mice of these molecules. It was also evaluated the roles of the atypical chemokine receptor ACKR2 – a scavenger CC chemokine receptor that could reduce CCL3 and other chemokines availability at tumor sites. In vitro experiments were also performed employing OSCC lineages to analyze possible CCL3 direct effects in these cells. The results showed that chemically-induced OSCC lesions exhibited increased expression of CCL3. Deficient mice for CCL3 (CCL3-/-) and CCR5 (CCR5-/-) treated with the chemical carcinogen 4-Nitroquinoline-1-oxide (4NQO) presented decreased tongue tumor formation when compared to wild type (WT) and CCR1 (CCR1-/-) deficient mice. Consistently, microscopical analysis demonstred attenuated cytomorphological atypia and reduced proliferation in lesions of CCL3-/- and CCR5-/- treated mice. It was verified that CCL3-/- mice lesions exhibited reduced expression of factors Epidermal growth factor (EGF), Fibroblast growth factor-1 (FGF 1), Transforming growth factor-β1 (TGF-β1), Vascular endothelial growth factor a (VEGFa) and VEGFb, the adhesion molecules Integrin-4 (ITGA-4) and Vitronectin (VTN) and matrix metalloproteinases (MMP-1a, MMP-2 and MMP-9). In vitro, CCL3 was able to induce invasiveness and release of CCL5, IL-6, and MMP’s 2, 8 and 9 by neoplastic cells. Blockage of CCL3 using anti-CCL3 antibody reduced invasion of neoplastic cells. Deficient mice for receptor ACKR2 (ACKR2-/-) treated exhibited similarity in tongue tumor formation and in microscopical parameters when compared with wild type mice. Moreover, it was observed increased expression of chemokines CCL3, CCL4, CCL5, CCL12 and the receptors CCR1, CCR2 and CCR5, as well as pro-inflammatory cytokines, angiogenic factors, adhesion molecules and matrix metalloproteinases in lesions of both treated groups in comparison with controls. However, increased expression of CCL2, IL-6 and IL-17 were observed in tongue lesions of ACKR2-/- in relation to WT group. Collectively, the data suggest the relevance of CCL3/CCR5 axis in oral carcinogenesis once CCL3 is able to directly affect neoplastic cells and the tumor microenvironment. The ACKR2 receptor did not modify the course of oral carcinogenesis. These results reveal potential protective effects of CCL3 blockage in OSCC.