Avaliação do efeito da proteína Pentraxina 3 em células tumorais murinas

Abstract

Pentraxin 3 (PTX3) is an inflammatory protein that plays important role in innate immunity, matrix deposition and female fertility. Moreover, it is a natural antagonist of fibroblast growth factor 2 (FGF2) that inhibit the cellular proliferation and angiogenesis promoted by this factor. PTX3 binds to FGF2 in the site of interaction with its receptor (FGFR) preventing the activation of FGF2/FGFR signaling pathway and, as a consequence, inhibiting the expression of genes related to cell proliferation, migration, differentiation, survival and angiogenesis. Neoplasms are among the leading causes of death worldwide and the estimatives point to an increase in incidence of this type of disease. The FGF signaling pathway is crucial in tumor biology by regulating essential processes in tumorigenesis, as cell proliferation and angiogenesis. The identification of inhibitors of this pathway is important for the understanding of the biology of cancer and for the development of therapeutic approaches aimed at controlling growth and tumor progression. The objective of this study was to evaluate the biological effect of PTX3 in murine tumor cell lines derived from melanocytic melanoma (B16F10 and B16F1), amelanocytic melanoma (K1735 and K1735 M2) and fibrosarcoma (MC-TGS17-51 and Sal/N). The morphology of the cells was assessed by optical phase contrast microscopy and the structure of the actin cytoskeleton by immunofluorescence. Cell proliferation was evaluated by MTT assay and gene expression profile was measured by RT-PCR. Under our experimental conditions, PTX3 did not promote morphological changes or in the pattern of organization of actin in the cells K1735 M2 and B16F1. A higher number of viable cells compared to control was observed in response to the treatment with PTX3 in all types of cells. The expression of the FGF receptors (FGFR) 1, 3 and 4 was verified in all cells but the expression of FGFR2 was detected only in the lineage of fibrosarcoma Sal/N. Ptx3 was expressed by almost all cell lines but not by K1735 melanoma. No FGF2 basal expression was observed in B16F1 melanoma. Our data corroborate the findings of lack of expression of FGFR2 in tumors, particularly melanomas. We show here, for the first time, the expression of PTX3 in murine fibrosarcomas and melanomas. The results presented here contribute to the functional characterization of PTX3 and point out the need for studies aiming the evaluation of its role in the tumor microenvironment and the potencial usage of PTX3 as a biomarker for the diagnosis and prognosis of tumors.