Avaliação do efeito biológico da pentraxina 3 em linhagens de células tumorais humanas

Abstract

The pentraxin 3 is an acute phase glycoprotein expressed in a wide variety of cells and plays a myriad of roles in biological processes including female fertility, innate immunity and angiogenesis. PTX3 interacts selectively and specifically to fibroblast growth factors (FGFs) preventing the engagement of these factors with their specific tyrosine kinase receptors (FGFRs). The FGF/FGFR system plays important roles in many processes such as migration, differentiation, survival and cell proliferation, and in angiogenesis. Angiogenesis contributes to the development and progression of a variety of physiological and pathological conditions. In cancer, the formation of new vascular channels favors the proliferation of tumor cells, local invasion and metastasis. The possibility of modulating angiogenesis by altering the balance between pro- and anti-angiogenic factors therefore has great therapeutic potential. In this sense, studies aiming the identification and functional characterization of molecules such as PTX3, which is a natural antagonist of FGF/FGFR system, are very important. The objectives of this study were to characterize the expression of PTX3 in human cells derived from sarcoma (HT 1080, SAOS 2), colon (HCT 116, CACO 2 and SW 480) and melanoma (SK-MEL 37 and SK-MEL 188) and to evaluate its effect on cell proliferation and expression of genes related to inflammatory response and angiogenesis. Gene expression profile was investigated by RT-PCR and cell proliferation assessed by MTT assay and by counting cells stained with Trypan Blue dye. Morphology was observed by contrast phase optical microscopy and immunofluorescence using rhodamine-phalloidin conjugated to TRITC to assess F-actin filaments. We found that tumor cell lines HT 1080, HCT 116, SK-MEL 37 and SK-MEL 188 express FGF 2 and all the FGF receptors investigated (FGFR 1-4). None of the cells expressed FGF8. PTX3 basal expression was observed in HT 1080, HCT 116, SK-MEL 188 e CACO 2 lines. Preliminary results indicate that PTX3 impair the proliferation of human fibrosarcoma HT 1080 cells. By immunofluorescence, we found that PTX3 seems to interfere with the structure of actin filaments, and reduces the number of filopodia in HT 1080 cells and human colorectal adenocarcinoma HCT 116 cells. These results indicate the need for further investigation of the role of PTX3 in FGF -dependent human tumor cells migration and proliferation as well as for the evaluation of the therapeutic potential of PTX3 as an anti - angiogenic tool.