Fe₃O₄ and Fe₃O_4core Au_shell-based Hyperthermia Reduces Expression of Proliferation Markers Ki-67, TOP2A and TPX2 in a...

Hyperthermia represents an adjuvant local anticancer strategy which relies on the increase of temperature beyond the physiological level. In this study, we investigated the anticancer potential of Fe₃O₄ and Fe₃O_4core Au_shell nanoparticles as hyperthermic agents in terms of cytotoxicity and studied the expression of cellular markers of proliferation (changes in mRNA levels via real-time polymerase chain reaction).

The human breast cancer cell line SK-BR-1 was incubated with either Fe₃O₄ or Fe₃O_4core Au_shell nanoparticles stabilized with tryptophan, prior to hyperthermia treatment. The normal HEK293 cell line was used as a control. Toxicity was determined using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay to estimate possible toxic effects of the tested nanoparticles. After RNA extraction and cDNA synthesis, mRNA expression of three indicators of proliferation, namely marker of proliferation Ki-67, DNA topoisomerase II alpha (TOP2A) and TPX2 microtubule nucleation factor (TPX2), was investigated.

At each concentration tested, Fe₃O_4core Au_shell nanoparticles showed greater toxicity compared to Fe₃O₄, while SK-BR-3 cells were more susceptible to their cytotoxic effects compared to the HEK293 cell line. The expression of Ki-67, TOP2A and TPX2 was reduced in SK-BR-3 cells by both Fe₃O₄ or Fe₃O_4core Au_shell nanoparticles compared to untreated cells, while the only observed change in HEK293 cells was the up-regulation of TOP2A.

Both Fe₃O_4core Au_shell and Fe₃O₄ NPs exhibit increased cytotoxicity to the cancer cell line tested (SK-BR-3) compared to HEK293 cells. The down-regulation in SK-BR-3 cells of the three proliferative markers studied, Ki-67, TOP2A and TPX2, after incubation with NPs suggests that cells that survived thermal destruction were not actively proliferating.