The HIF1-alpha; and FASN overexpression by palmitic acid and fructose induced tumorigenesis in breast adenocarcinoma

FERRERO VICTORIA; MAZO TAMARA; BAROTTO NELSO N; DON JULIETA; MOREIRA- ESPINOZA MJ; YENNERICH LAURA; GRANTON FLORENCIA; MAZZUDULLI GEORGINA; LAGARES CLARISA; RODRIGUEZ VALERIA; PASQUALINI MARIA EUGENIA

Rosario

Congreso; LIX Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research (SAIB); 2023

Cancer cells are characterized by their ability to maintain uncontrolled cell proliferation. The fatty acid synthase (FASN) is a key enzyme in the synthesis of membrane components necessary for cell division since it mediates de novo lipid synthesis catalyzing the production of fatty acids such as palmitic acid (PA) (1,2). Activation of the FASN gene is regulated by the alpha subunit of hypoxia-inducible factor 1 alpha (HIF1-α), which contributes to increased glycolysis in breast cancer (3). We proposed to investigate the effects of dietary palmitic acid (PA) and fructose (Fr) on FASN and HIF1-α expression during breast cancer development in BALB/c mice. Mice were divided into four dietary groups (n=20 each): CONTROL (6% corn oil + 30% Fr), PCS (20% palm oil + 15% Fr), PBA (20% corn oil + 45% Fr) and PCS+PBA (20% palm oil + 45% Fr). After 90 days on dietary treatment, mice were inoculated with murine breast adenocarcinoma cells (LM3: 1x106 cells). At 120 days, we evaluate biochemical blood profile and cancer growth parameters as tumor size, metastasis, tumor necrosis and infiltration (histopathology), Ki67 tumor expression (immunohistochemistry), tumor lipid profile (gas chromatography), and tumor FASN and HIF1-α expression (by western blot, qPCR and immunohistochemistry). In vitro experiments were performed using LM3 cells treated with AP (40µM), Fr (2.5mM) and the combination of both treatments(AP+Fr). We analyzed cell viability, proliferation (using Resazurin and Hoechst), FASN expression (by western blot) and lipid profile (by gas chromatography). Experiments were repeated at least three times and analyzed by ANOVA (p<0.05). Mice that were fed with PCS+PBA diet showed a significant increment in tumor growth, infiltration and necrosis (p<0.05). The PCS group presented the highest AP content in tumor tissue, while the PBA group showed highest ω-6 PUFAs (p<0.05). The PCS+PBA diet induced an increment in FASN expression (by immunohistochemistry and western blot, p<0.0001) and high HIF1-α expression (by immunohistochemistry, p<0.0001). Fr-rich diet (PBA) increased FASN mRNA expression in tumor tissue (p<0.05, by qPCR) and Ki67 by IHQ (p<0.0041). Cell treatments with AP (40µM) and Fr (2.5mM) reduced apoptosis and increased viability compared to the control group (p<0.05). The combination of AP and Fr (40µM/2.5mM) of cell treatments increased FASN expression (by western blot, p<0.006). In conclusion, diets rich in palmitic acid and fructose promote higher FASN and HIF1-α expression, which in turn, stimulates cell proliferation in murine breast cancer.