Abstract
BACKGROUND: Mesoporous titanium dioxide nanoparticles (mTiNPs) are known for their chemical stability, non-toxicity, antimicrobial and anticancer effects, as well as for their photocatalytic properties. When this material is subjected to UV radiation, its electronic structure shifts, and during that process, reactive oxygen species are generated, which in turn exert apoptotic events on the cancer cells. OBJECTIVES: We evaluated the cytotoxic effects of UV-irradiated mTiNPs on prostate cancer (PCa) cell line PC3 with the aim of demonstrating that the interaction between UV-light and mTiNPs positively impacts the nanomaterial's cytotoxic efficiency. Moreover, we assessed the differential expression of key oncomiRs and tumor suppressor (TS) miRNAs, as well as their associated target genes, in cells undergoing this treatment. METHODS: PBS-suspended mTiNPs exposed to 290 nm UV light were added at different concentrations to PC3 cells. Cell viability was determined after 24 h with a crystal violet assay. Then, the obtained IC(50) concentration of UV-nanomaterial was applied to a new PC3 cell culture, and the expression of a set of miRNAs and selected target genes was evaluated via qRT-PCR. RESULTS: The cells exposed to photo-activated mTiNPs required 4.38 times less concentration of the nanomaterial than the group exposed to non-irradiated mTiNPs to achieve the half-maximal inhibition, demonstrating an improved cytotoxic performance of the UV-irradiated mTiNPs. Moreover, the expression of miR-18a-5p, miR-21-5p, and miR-221-5p was downregulated after the application of UV-mTiNPs, while TS miR-200a-5p and miR-200b-5p displayed an upregulated expression. Among the miRNA target genes, PTEN was found to be upregulated after the treatment, while BCL-2 and TP53 were underexpressed. CONCLUSIONS: Our cytotoxic outcomes coincided with previous reports performed in other cancer cell lines, strongly suggesting UV-irradiated mTiNPs as a promising nano-therapeutic approach against PCa. On the other hand, to the best of our knowledge, this is the first report exploring the impact of UV-irradiated mTiNPs on key onco- and TS microRNAs in PCa cells.