Polyoxometalates as antitumor agents: Bioactivity of a new polyoxometalate with copper on a human osteosarcoma model

[Display omitted] •The bioactivity of the HPOM with copper(II) was investigated in osteoblast-like cells.•The antitumor potency was: MC3T3-E1>UMR106>MG-63.•The compound induced cytotoxicity that caused impaired cell viability.•Oxidative stress, apoptosis and cell cycle arrest were the main mechanisms of action. Polyoxometalates (POMs) are early transition metal oxygen anion clusters. They display interesting biological effects mainly related to their antiviral and antitumor properties. On the other hand, copper compounds also show different biological and pharmacological effects in cell culture and in animal models. We report herein for the first time, a detailed study of the mechanisms of action of a copper(II) compound of the group of HPOMs with the formula K7Na3[Cu4(H2O)2(PW9034)2]20H2O (PW9Cu), in a model of human osteosarcoma derived cell line, MG-63. The compound inhibited selectively the viability of the osteosarcoma cells in the range of 25–100μM (p