Anticancer and antimetastatic activity of copper(II)-tropolone complex against human breast cancer cells, breast multicellular spheroids and mammospheres

The goal of this work was to display the anticancer and antimetastatic activity of a copper(II) with tropolone (trp), complex [ Cu(trp) 2 ] toward human breast cancer cells in monolayer (2D) and spheroids (3D). Cytotoxicity assays against MCF7 (IC 50(complex)  = 5.2 ± 1.8 μM, IC 50(CDDP)  = 19.3 ± 2.1 μM) and MDA-MB-231 (IC 50(complex)  = 4.0 ± 0.2 μM, IC 50(CDDP)  = 27.0 ± 1.9 μM) demonstrate that [ Cu(trp) 2 ] exert greater antitumor potency than cisplatin (CDDP) on 2D and 3D human breast cancer cell models. Besides, [ Cu(trp) 2 ] inhibits cell migration by reducing the metalloproteinases activities and the compound undergoes the breast cancer cells to apoptosis at lower concentrations (2.5–10 μM). Moreover, [ Cu(trp) 2 ] overcame CDDP presenting an IC 50 value 26-fold more lower against breast multicellular spheroids ((IC 50(complex)  = 4.9 μM, IC 50(CDDP)  = 130 μM)). Also, our results showed that [ Cu(trp) 2 ] inhibited the cell migration and cell invasion of breast multicellular spheroids, showing that [ Cu(trp) 2 ] exhibited antimetastatic properties. On the other hand, [ Cu(trp) 2 ] reduced mammosphere forming capacity affecting the size and number of mammospheres. Taken together, [ Cu(trp) 2 ] exhibited anticancer and antimetastatic properties on monolayer (2D) and spheroids (3D) derived from human breast cancer cells.