Evaluation of in vitro cytotoxicity, biocompatibility, and changes in the expression of apoptosis regulatory proteins induced by cerium oxide nanocrystals

Shahanavaj Khan; Anees A Ansari; Christian Rolfo; Andreia Coelho; Maha Abdulla; Khayal Al-Khayal; Rehan Ahmad

doi:10.1080/14686996.2017.1319731

Evaluation of in vitro cytotoxicity, biocompatibility, and changes in the expression of apoptosis regulatory proteins induced by cerium oxide nanocrystals

Sci Technol Adv Mater. 2017 May 31;18(1):364-373. doi: 10.1080/14686996.2017.1319731. eCollection 2017.

Authors

Shahanavaj Khan^{1

2}, Anees A Ansari³, Christian Rolfo⁴, Andreia Coelho⁴, Maha Abdulla⁵, Khayal Al-Khayal⁵, Rehan Ahmad⁵

Affiliations

¹ Nanomedicine & Biotechnology Research Unit, Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.
² Department of Bioscience, Shri Ram Group of College (SRGC), Muzaffarnagar, India.
³ King Abdullah Institute for Nanotechnology, King Saud University, Riyadh, Saudi Arabia.
⁴ Phase I- Early Clinical Trials Unit, Oncology Department and Multidisciplinary Oncology Center Antwerp (MOCA), Antwerp University Hospital, Edegem, Belgium.
⁵ Colorectal Research Center, College of Medicine King Saud University, Riyadh, Saudi Arabia.

Abstract

Cerium oxide nanocrystals (CeO₂-NCs) exhibit superoxide dismutase and catalase mimetic activities. Based on these catalytic activities, CeO₂-NCs have been suggested to have the potential to treat various diseases. The crystalline size of these materials is an important factor that influences the performance of CeO₂-NCs. Previous reports have shown that several metal-based nanocrystals, including CeO₂-NCs, can induce cytotoxicity in cancer cells. However, the underlying mechanisms have remained unclear. To characterize the anticancer activities of CeO₂-NCs, several assays related to the mechanism of cytotoxicity and induction of apoptosis has been performed. Here, we have carried out a systematic study to characterize CeO₂-NCs phase purity (X-ray diffraction), morphology (electron microscopy), and optical features (optical absorption, Raman scattering, and photoluminescence) to better establish their potential as anticancer drugs. Our study revealed anticancer effects of CeO₂-NCs in HT29 and SW620 colorectal cancer cell lines with half-maximal inhibitory concentration (IC₅₀) values of 2.26 and 121.18 μg ml^-1, respectively. Reductions in cell viability indicated the cytotoxic potential of CeO₂-NCs in HT29 cells based on inverted and florescence microscopy assessments. The mechanism of cytotoxicity confirmed by estimating possible changes in the expression levels of Bcl2, BclxL, Bax, PARP, cytochrome c, and β-actin (control) proteins in HT29 cells. Down-regulation of Bcl2 and BclxL and up-regulation of Bax, PARP, and cytochrome c proteins suggested the significant involvement of CeO₂-NCs exposure in the induction of apoptosis. Furthermore, biocompatibility assay showed minimum effect of CeO₂-NCs on human red blood cells.

Keywords: 10 Engineering and Structural materials; 102 Porous / Nanoporous / Nanostructured materials; CeO2-nanocrystals; apoptotic pathways; cancerous cell lines; hemolysis assay; in vitro; nanotechnology.