Ectophosphatase activity in the triple‐negative breast cancer cell line MDA‐MB‐231

Abstract

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 Km = 4.5 ± 0.5 mM para‐nitrophenylphosphate and a Vmax = 2280 ± 158 nM × h−1 × mg protein−1. 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.

Hydrogen phosphate selectively induces MDA MB 231 triple negative breast cancer cell death in vitro

“…Interestingly, they have high affinity for P i in its diprotic form (H 2 PO 4 − ), which exists at physiological pH, and low affinity for P i in its monoprotic form (HPO 4 2− ), which exists at alkaline pH 1 . Since triple negative breast cancer cells are known to require elevated amounts of phosphate to meet their metabolic demands, failure to efficiently transport phosphate into cancer cells alters their functioning and probably leads to cellular death 30 , 31 . This study demonstrates that phosphate in its monoprotic form (HPO 4 2− ) causes significant death in MDA-MB-231 cells but not in THP-1 cells, unlike phosphate in its diprotic form.…”

Resveratrol is an inhibitor of sodium‐dependent inorganic phosphate transport in triple‐negative MDA‐MB‐231 breast cancer cells

“…Five random fields in each insert were photographed at a magnification of ×20. Quantification is expressed as the percentage of the area covered with migrated cells determined using ImageJ software (Lacerda‐Abreu et al, 2021).…”

Hydrogen Phosphate Selectively Induces MDA-MB-231 Breast Cancer Cell Death in vitro

“…Interestingly, they have high a nity for P i in its diprotic form (H 2 PO 4 ), which exists at physiological pH, and low a nity for P i in its monoprotic form (HPO 4 2− ), which exists at alkaline pH 1 . Since triple negative breast cancer cells are known to require elevated amounts of phosphate to meet their metabolic demands, failure to e ciently transport phosphate into cancer cells alters their functioning and probably leads to cellular death 30,31 .…”