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  • br a Laboratory of Biochemistry and Animal Toxins

    2020-08-02


    a Laboratory of Biochemistry and Animal Toxins, Institute of Biotechnology, Federal University of Uberlandia, UFU, MG, Brazil
    b Laboratory of Nanobiotechnology, Institute of Biotechnology, Federal University of Uberlandia, UFU, Brazil
    c Multidisciplinary Institute of Health, Federal University of Bahia, Vitoria da Conquista, Brazil
    d Federal University of Alagoas, UFAL, Brazil
    Article history:
    Keywords:
    BthTX-II
    EMT
    Breast cancer Phospholipase A2-snake venom 
    This work shows the antitumor and antimetastatic effects of BthTX-II, an Asp-49 PLA2 from Bothrops jararacussu venom, on MDA-MB-231 human triple negative breast cancer cells. BthTX-II caused a dose-dependent cell death of MDA-MB-231 cells when compared with the non-tumorigenic breast cells by inducing apoptosis and autoph-agy. BthTX-II was also able to decrease the proliferation and to inhibit Etoposide progression. We also observed an upregulation of the ATM gene, which is responsible for cell-cycle arrest and DNA repair such as CCND1, CCNE1, CDC25A, E2F1, AKT1 and AKT3. Interestingly, BthTX-II inhibited invasion, migration and 3D cell growth of MDA-MB-231 cells, as well as inhibited the epithelial–mesenchymal transition (EMT) of this cell by increasing E-cadherin (CDH-1) and decreasing TWIST1, CTNNB1, vimentin and cytokeratin-5 expression. In conclusion, these results showed that BthTX-II displays antitumor and antimetastatic effects on MDA-MB-231 cells and may be useful for the development of new approaches and therapeutic strategies to manage triple negative breast cancer. © 2019 Published by Elsevier B.V.
    1. Introduction
    Breast cancer is the most common cancer in women worldwide and the second cause of death after lung cancer [1–3]. This disease harbors an extensive heterogeneity and classifies into several subtypes based on the distinct biological characteristics. One of these subtypes is the triple-negative breast cancer (TNBC), which is characterized by the lack of the expression of the estrogen receptor (ER), the progesterone receptor (PR) and the human epidermal growth factor receptor 2 (HER2). TNBC accounts for 10–20% of all diagnosed breast cancer cases throughout the world [4,5], and associates with an unfavorable prognosis due to its high metastatic potential and high recurrence rate compared to other BC subtypes. TNBC derives no benefit from anti-estrogen or anti HER2 therapies, because they lack the appropriate tar-gets for the action of these drugs. Therefore, chemotherapy, radiother-apy and surgery are the only treatment options for TNBC patients [6].
    Corresponding authors at: Federal University of Uberlandia, Para Avenue, 1720, 38400-902 Uberlândia, MG, Brazil. E-mail addresses: [email protected] (F.V.P. de Vasconcelos Azevedo), [email protected] (V. de Melo Rodrigues). 
    The acquisition of the ability to invade other tissues represents an important event in cancer progression since determines the metastatic potential of tumor cells. This ability occurs through a process called ep-ithelial to mesenchymal transition (EMT), characterized by multiple biochemical changes that enable the cell to acquire a mesenchymal phe-notype, with characteristics of loss of cell-cell adhesion, and cell polarity and by the reorganization of the cytoskeleton. The acquisition of this phenotype is accompanied by a decreased expression of epithelial markers and by profound changes in cell signaling and gene expression. Upon suffering the EMT process, cells present elevated expression of not only intermediate filament proteins such as vimentin, fibronectin and N-cadherin, and of cytokeratins, including CK5/6, CK14 and CK20, which correlate positively with a high tumor grade. High levels of CK-5 expression have been observed in patients with malignant breast can-cer [7–9]. These molecular events enhance migration, invasiveness, re-sistance to apoptosis, and greatly increase the production of extracellular matrix (ECM) components, to create the dramatic changes toward the mesenchymal cell phenotype [7,8,10–12].
    One of the signaling pathways that are involved in the EMT process is the PI3K/AKT pathway involved in the promotion of cell growth and survival and in the increase of cell motility by means of its downregula-tion activity on the cell adhesion molecule CDH-1 (Cadherin-1). E-
    cadherin is considered a pre-requisite for EMT and in contrast to other tumor gene suppressors, is rarely mutated in cancer [8,13–15], thus allowing the development of an invasive phenotype to emphasize its transient nature [16]. Some studies have demonstrated that either EGF stimulation or the overexpression of the transcription factor Twist1 can induce the process of EMT in breast cancer cells [17,18].