Yttrium Oxide nanoparticles induce cytotoxicity, genotoxicity, apoptosis, and ferroptosis in the human triple-negative breast cancer MDA-MB-231 cells.

Background: Triple-negative breast cancer (TNBC) is a lethal mammary carcinoma subtype that affects females and is associated with a worse prognosis. Chemotherapy is the only conventional therapy available for patients with TNBC due to the lack of therapeutic targets. Yttrium oxide (YO) is a rare earth metal oxide, whose nanoparticle (NPs) formulations are used in various applications, including biological imaging, the material sciences, and the chemical synthesis of inorganic chemicals. However, the biological activity of YO-NPs against TNBC cells has not been fully explored. The current study was conducted to assess YO-NPs' anticancer activity against the human TNBC MDA-MB-231 cell line.

Methods: Transmission electron microscopy (TEM), X-ray diffraction, Zeta potential, and dynamic light scattering (DLS) were used to characterize the YO-NPs. SRB cell viability, reactive oxygen species (ROS) measurement, single-cell gel electrophoresis (comet assay), qPCR, flow cytometry, and Western blot were employed to assess the anticancer activity of the YO-NPs.

Results: Our results indicate favorable physiochemical properties of YO-NPs (with approximately average size 14 nm, Zeta Potential about - 53.2 mV, and polydispersity index = 0.630). YO-NPs showed a potent cytotoxic effect against MDA-MB-231 cells, with IC50 values of 74.4 µg/mL, without cytotoxic effect on the normal retina REP1 and human dermal fibroblast HDF cell lines. Further, treatment of MDA-MB-231 cells with IC50 YO-NPs resulted in increased oxidative stress, accumulation of intracellular ROS levels, and induced DNA damage assessed by Comet assay. Upon YO-NPs treatment, a significant increase in the early and late phases of apoptosis was revealed in MDA-MB-231 cells. qPCR results showed that YO-NPs significantly upregulated the pro-apoptotic genes CASP3 and CASP8 as well as ferroptosis-related gene heme oxygenase-1 (HO-1), whereas the anti-apoptotic gene BCL2 was significantly downregulated.

Conclusion: This study suggests that YO-NPs are safe on normal REP1 and HDF cells and exhibited a potent selective cytotoxic effect against the TNBC MDA-MB-231 cells through increasing levels of ROS generation with subsequent DNA damage, and induction of apoptosis and ferroptosis.