Apoptosis induction in colon cancer cells (SW480) by BiFe2O4@Ag nanocomposite synthesized from Chlorella vulgaris extract and evaluation the expression of CASP8, BAX and BCL2 genes

Abstract

Background: The use of nanomaterials in cancer diagnosis and treatment has received considerable interest. Preparation of nanoscale complex molecules could be considered to improve the efficacy and minimize toxicity of the product. This work aimed to biosynthesize BiFe₂O₄@Ag nanocomposite using the Chlorella vulgaris extract and its cytotoxic effect on colon cancer cell line.

Methods: The physicochemical properties of the bioengineered BiFe₂O₄ @Ag were investigated by Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), Zeta potential, Dynamic Light Scattering (DLS), Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive X-ray Spectroscopy (EDX), Vibrating-sample Magnetometer (VSM) and X-ray Diffraction Analysis (XRD). The cytotoxic potential of BiFe₂O₄ @Ag was evaluated by MTT assay against SW480 colon cancer cell line. The expression levels of apoptotic genes including BAX, BCL2 and CASP8 were determined by Real-time PCR. The rate of apoptosis and necrosis of the cancer cells as well as the cell cycle analysis were evaluated by flow cytometry.

Results: Physicochemical assays indicated the nanoscale synthesis (10-70 nm) and functionalization of BiFe₂O₄ nanoparticles by Ag atoms. The VSM analysis revealed the magnetism of BiFe₂O₄ @Ag nanocomposite. According to the MTT assay, colon cancer cells (SW480) were considerably more sensitive to BiFe₂O₄ @Ag nanocomposite than normal cells. Apoptotic cell percentage increased from 1.93% to 73.66%, after exposure to the nanocomposite. Cell cycle analysis confirmed an increase in the number of the cells in subG1 and G0/G1 phases among nanocomposite treated cells. Moreover, treating the colon cancer cells with BiFe₂O₄ @Ag caused an increase in the expression of CASP8, BAX, and BCL2 genes by 3.1, 2.6, and 1.2 folds, respectively. Moreover, activity of Caspase-3 protein increased by 2.4 folds and apoptotic morphological changes appeared which confirms that exposure to the nanocomposite induces extrinsic pathway of apoptosis in colon cancer cells.

Conclusion: The considerable anticancer potential of the synthesized BiFe₂O₄ @Ag nanocomposite seems to be related to the induction of oxidative stress which leads to inhibit cell cycle progression and cell proliferation. This study reveals that the BiFe₂O₄ @Ag is a potent compound to be used in biomedical fields.

Keywords: Apoptosis; Bismuth; Colon cancer; Nanocomposite; SW480.