Avaliação imunohistoquímica de marcadores associados à progressão tumoral metastática de animais obesos

Abstract

Obesity affects more than 300 million people worldwide and is associated with diseases such as type 2 diabetes, cardiovascular diseases and cancers. As obesity, cancer is currently a global public health problem increasing 20% annually. There is a positive correlation between the incidence of tumors with poor prognosis and obesity. The degradation of extracellular matrix components (ECM) in the tumor microenvironment is associated with tumor cells migration through basement membranes, bone barrier and interstitial stroma. Molecules associated with ECM such as extracellular matrix metalloproteinase (MMP-2, 3, 9, 11 and 13) help the degradation of ECM, and so promote tumor cell migration. Therefore, these molecules are associated with tumor progression stages as well as their inhibitors (TIMP-1, TIMP-2 and RECK), and other ECM components such as fibronectin and collagen IV. Thus, the identification of these molecules associated with the metastatic process in obese mice and the elucidation of their role in this process are important to explore new methods for early diagnosis, prognostic evaluation and standardization of new therapeutic strategies. Thus, this study aimed to evaluate and compare markers associated with metastatic processes in obese and control animals by immunohistochemistry. For that purpose, obesity was induced for 12 or 16 weeks by a high fat diet ( 60% of the kilocalories is from lipids). At the end of those weeks, breast cancer was induced by metastatic cell line 4T1 with intradermal injection in the upper breast BALB / c mice (n = 40). These animals were euthanized after 14 or 21 days and the tumors were collected. Histopathology analysis of the tumors was performed by Hematoxylin-Eosin staining. As result, it was observed an increase in lipid vacuoles, which may contribute to the recruitment of immune cells such as tumor growth factors in obese animals compared to control animals. The immunohistochemistry analysis shows a higher concentration of MMP-3, 9, 11, 13 expressions in obese animals and a lower concentration of their inhibitor RECK, suggesting a more aggressive tumor invasion in those animals. Regarding the fibronectin and collagen type IV were found higher concentrations in obese animals compared to controls. However, TIMP-1 and TIMP-2, showed an upregulation in obese, as found in the literature. Thus, the results indicate more invasive breast cancer progression and so a worse prognosis in obese animals when compare to controls.