Instituto de Bioquímica Médica Leopoldo De Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, State of Rio de Janeiro, Brazil.
Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, State of Rio de Janeiro, Brazil.
Cell Biol Int. 2021 Feb;45(2):411-421. doi: 10.1002/cbin.11497. Epub 2020 Nov 10.
Breast cancer is one of the most common cancers in the female population worldwide, and its development is thought to be associated with genetic mutations that lead to uncontrolled and accelerated growth of breast cells. This abnormal behavior requires extra energy, and indeed, tumor cells display a rewired energy metabolism compared to normal breast cells. Inorganic phosphate (Pi) is a glycolytic substrate of glyceraldehyde-3-phosphate dehydrogenase and has an important role in cancer cell proliferation. For cells to obtain Pi, ectoenzymes in the plasma membrane with their catalytic site facing the extracellular environment can hydrolyze phosphorylated molecules, and this is an initial and possibly limiting step for the uptake of Pi by carriers that behave as adjuvants in the process of energy harvesting and thus partially contributes to tumor energy requirements. In this study, the activity of an ectophosphatase in MDA-MB-231 cells was biochemically characterized, and the results showed that the activity of this enzyme was higher in the acidic pH range and that the enzyme had a K = 4.5 ± 0.5 mM para-nitrophenylphosphate and a V = 2280 ± 158 nM × h × mg protein . In addition, classical acid phosphatase inhibitors, including sodium orthovanadate, decreased enzymatic activity. Sodium orthovanadate was able to inhibit ectophosphatase activity while also inhibiting cell proliferation, adhesion, and migration, which are important processes in tumor progression, especially in metastatic breast cancer MDA-MB-231 cells that have higher ectophosphatase activity than MCF-7 and MCF-10 breast cells.
乳腺癌是全球女性人群中最常见的癌症之一，其发展被认为与导致乳腺细胞失控和加速生长的基因突变有关。这种异常行为需要额外的能量，事实上，与正常乳腺细胞相比，肿瘤细胞显示出重新布线的能量代谢。无机磷酸盐（Pi）是甘油醛-3-磷酸脱氢酶的糖酵解底物，在癌细胞增殖中具有重要作用。为了让细胞获得 Pi，质膜中的外切酶可以将其催化部位朝向细胞外环境，水解磷酸化分子，这是载体摄取 Pi 的初始且可能是限制步骤，这些载体在能量收获过程中充当辅助因子，从而部分有助于肿瘤的能量需求。在这项研究中，我们对 MDA-MB-231 细胞中的一种外切磷酸酶的活性进行了生化特征分析，结果表明该酶在酸性 pH 范围内具有更高的活性，其 K = 4.5 ± 0.5 mM 对硝基苯磷酸和 V = 2280 ± 158 nM × h × mg 蛋白。此外，包括偏钒酸钠在内的经典酸性磷酸酶抑制剂降低了酶活性。偏钒酸钠能够抑制外切磷酸酶活性，同时抑制细胞增殖、黏附和迁移，这些都是肿瘤进展的重要过程，特别是在具有更高外切磷酸酶活性的转移性乳腺癌 MDA-MB-231 细胞中，这种活性高于 MCF-7 和 MCF-10 乳腺细胞。
