The anti-tumor effect of p53 gene-loaded hydroxyapatite nanoparticles in vitro and in vivo

This research focused on anti-tumor effect of pEGFP-C1-p53 (p53) gene-loaded hydroxyapatite (HAp) nanoparticles in vitro and in vivo. Four kinds of HAp nanoparticles, spherical HAp nanoparticles (S-HAp, diameter: 50 nm), needle-like HAp nanoparticles (N-HAp, average length: 110 nm and width: 30 nm), rod-like HAp nanoparticles (R-HAp, average length: 100 nm and width: 30 nm), and short-rod-like HAp nanoparticles (SR-HAp, average length: 40 nm and width: 30 nm), were prepared initially. The HAp nanoparticles with or without being modified by PEI (named HAp and HAp-PEI, respectively) have excellent biocompatibility as shown by MTT assay and crystal violet staining tests. Then, the subsequent MTT, Hocehst staining tests, and Western blot showed that the killing effect of p53-loaded HAp-PEI (HAp-PEI-p53) was effective with fair selectivity toward Hep-3B and HuH-7 cells’ cell lines. Moreover, HAp-PEI-p53 could inhibit the tumor growth in vivo, and the mechanism of tumor growth inhibition was verified by the hematoxylin and eosin staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, P53 protein immunohistochemistry, and transmission electron microscope of the tumor cell in vivo. We found that HAp-PEI-p53 has good anti-cancer effect in vitro and in vivo, especially for the S-HAp-PEI-p53. Tumor metastasis could be suppressed significantly by the S-HAp-PEI-p53 and N-HAp-PEI-p53 treatments by the in vivo imaging system. All these results lead to the conclusion that the particle sizes of HAp ranging from 100 to 200 nm are appropriate for cancer gene therapy and may be widely used in anti-cancer investigation.