Ativação de AMPK com o uso de metformina em células normais e tumorais de próstata estimuladas por altas concentrações de insulina e ácido graxo

Abstract

A potential association between obesity and prostate cancer has been proposed by several studies. Obesity is related with multifactorial disorders, such as hyperglycemia, hyperinsulinaemia, dyslipidemia, and inflammation. Regarding the impact of such disorders on normal and tumor cells is of great relevance for the development of therapeutic strategies. Metformin, an antidiabetic drug, has antiproliferative effects, being proposed as a cancer treatment. However, under intense proliferative stimulation conditions, its efficiency is still uncertain. The main objective of the present study was to analyze the effects of fatty acid and/or insulin under high concentrations, in the presence or not of metformin, on normal and prostate tumor cells, regarding their proliferation and migration profile. Two human prostate epithelial cell lines were used: non cancer (PNT1A) and tumor (PC3). These cells were treated with high concentrations of saturated fatty acid (100 gM palmitate, HF), and/or insulin (50 gU) in the presence or absence of metformin (100 gM) for 24 or 48 hours. After treatments we performed analyzes for caspase, cell viability/proliferation (MTT), migration and immunofluorescence for vimentin. The results showed that the concentration of all treatments was not cytotoxic. MTT revealed that PNT1A and PC3 cells had higher proliferation when treated with HF and HI after the first few hours of treatment. Similar results were not found for the HFI group. Metformin alone has stimulated cell proliferation, but in association with HF, has reduced it in both cell lines. However it did not inhibit the proliferative action of HI in PNT1A cells. Migration analyzes showed that PNT1A were stimulated to migrate after all treatments, whilst PC3 was influenced only by HF and that metformin inhibited the migration stimulated by all of them. Both HF and HI treatments in PNT1A and HF in PC3 stimulated greater vimentin expression, resulting in a larger epithelium-mesenchymal transition in these cells, which, in turns, has stimulated cell migration. Metformin inhibited vimentin expression in both normal and tumor cells. It is possible to conclude that higher concentrations of saturated fatty acid and insulin influence prostatic cells, stimulating cellular activities that could trigger carcinogenesis and/or sustain cancer progression, such as cell proliferation and migration. Most of these stimuli were inhibited by using Metformin, being efficient in the control of cell proliferation and migration in conditions of hyperlipidemia and hyperinsulinemia. Thus, the efficiency of this drug for obese patients therapy, which is a potential group for prostrate cancer risk, should be investigated.