Prostate cancer (PCa) is one of the main causes of death and morbidity among men worldwide. Prior studies suggested that ZnO nanoparticles presented anticancer effects in different malignancies. The current study aims to synthesize ZnO nanoparticles (ZnO NPs) and investigate its anti-tumor effects in androgen-resistant prostate cancer cell lines.

The green synthesis of ZnO NPs (green tea extraction) involves production and full characterization. The structural and optical properties of ZnO NPs were examined by transmission electron microscope (TEM) and ultraviolet-visible spectrophotometer (UV-Vis). Hydrodynamic diameters and zeta (ζ) potentials were also measured. After the synthesis of ZnO NPs, androgen-resistant (DU145, PC-3), androgen-sensitive (LNCaP) human prostate cancer cell lines and BPH-1 control cell line were treated with different concentration of ZnO NPs (0 ug/ml, 6.25 ug/ml, 12.5 ug/ml, 25 ug/ml, 50 ug/ml and 100 ug/ml).

TEM unveiled the structure and characterization of successful ZnO NPs synthesis with size of 53 ± 12 nm (Figure 1A). The UV-Vis result revealed the formation of the nanoparticle (Figure 1B). The hydrodynamic diameter of ZnO NPs is 109 ± 26 nm with Zeta potential of -0.4 ± 0.1 mV (Figure 1C). ZnO NPs showed optimum in vitro stability in biologically relevant solutions. We observed a significant suppression of the cell growth in all of the four cell lines at 48 hrs (Figure 1D). The results from migration and cell cycle analysis furtherly confirmed that this suppression effect was more significant in androgen-resistant cell lines (p < 0.05) (Figure 1E and 1F). The ZnO NPs displayed cytotoxicity effects against cancer cells.

Our investigations provide compelling evidence that ZnO NPs serves as an excellent non-radioactive surrogate for the development of the corresponding NPS theragnostic nano-radiopharmaceutical for use in prostate cancer diagnosis and therapy.