Efeito biológico da proteína pentraxina 3 sobre as características morfológicas e fisiológicas de células tumorais humanas

• Ano de defesa: 2016
• Autor(a) principal: Octávio Mangabeira Sobrinho
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Pentraxina 3; Ciclo celular; Citoesqueleto; Apoptose; Genética
• Link de acesso: http://hdl.handle.net/1843/BUBD-AE7GKT

The pentraxin 3 is an acute phase glycoprotein which plays essential roles in innate immunity, inflammation, matrix deposition and female fertility. PTX3 binds with great affinity and specificity to Fibroblast Growth Factors type 2 and 8, inhibiting cell proliferation and angiogenesis promoted by these factors, and consequently growth of murine prostate and breast tumors. It has been shown that other members of the pentraxin family such as C-reactive protein and Neuronal pentraxin 2, induce apoptosis and cell cycle arrest in human monocytes and human pancreatic cancer cells, respectively. Our hypothesis is that the inhibitory action of pentraxin 3 on tumor progression is not only due to its role as a natural antagonist of the FGFs but also relies on its ability to promote cell cycle arrest and increased apoptosis. The objective of this study was to evaluate the biological effect of PTX3 protein on the morphology and physiology of colon adenocarcinoma (HCT-116) and human melanoma (SK-MEL-37) cells. Morphology was evaluated by using light phase-contrast microscopy and immunofluorescence. The gene expression profile of pro-apoptotic (BAX), anti-apoptotic (BCL2), cell cycle regulators (MYC, CDKN1A/p21 e TP53) genes was analyzed by qRT-PCR. Cell cycle arrest was assessed by flow cytometry. Our study showed that exogenous PTX3 protein promoted a slight reduction in the number of cells in the G0 / G1 phase 24 hours in the SK-MEL-37 line and 48 hours for the HCT-116 strain after the treatment. No membrane bubbles nor condensed nucleus, indicative of apoptosis, were found in the treated groups in both strains being possible to infer that PTX3, at a concentration of 2.64 mg / mL at times of 12, 24 and 48 hours protein did not induce apoptosis. Gene expression analysis by RT-qPCR showed that any of target genes were modulated by PTX3 in SK-MEL-37 cell line. Similarly, rhPTX3 promoted no difference in gene expression of BCL-2, MYC and P53 on HCT-116 line. However, CDKN1A gene expression were impaired in the treated cells in comparison with the control untreated group. These data reinforce our cell cycle assay findings, since PTX3 may be promoting the reduction in the number of cells in the G0 / G1 phase of HCT-116 cells by decreasing the amount of CDKN1A transcripts. According to our data, regulation of the transcription of CDKN1A gene promoted by PTX3 was independent of TP53. Our data indicate that PTX3 does not promote cell cycle arrest nor increases apoptosis in melanoma and colorectal adenocarcinomas. In the latter PTX3 seems to promote cell proliferation by decreasing the levels of CDKN1A transcripts in the cell.