Abstract
Radiotherapy is preferred to chemotherapy as an adjuvant therapy for postoperative cervical cancer owing to its convenience and minimal effects on various non-targeted systems. The present study sought to investigate whether the utilization of anti-MET proto-oncogene, receptor tyrosine kinase (c-Met) antibodies conjugated to hollow gold nanospheres (anti-c-Met/HGNs) may enhance the efficiency of radiation therapy for cervical cancer. Anti-c-Met/HGNs were synthesized and confirmed to target c-Met, which was overexpressed on the cell membrane of multiple malignancies. The successful synthesis of HGNs was observed using transmission electron microscopy (TEM). Overrepresentation of c-Met in the human cervical cancer cell line CaSki was verified by immunofluorescence. The cellular uptake of HGNs was assessed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). To assess the toxicity of functionalized gold nanospheres, a cell proliferation and toxicity assay was used and flow cytometry, with staining by propidium iodide (PI), was performed to study the cell cycle changes. Each experiment was conducted on three groups: Control, HGNs alone and anti-c-Met/HGNs, with each group also assessed with or without X-rays. The variation of apoptotic rate was observed by flow cytometry using a dual-staining Annexin V-fluorescein isothiocyanate/PI kit. Expression of apoptosis-associated proteins was examined by western blot analysis. TEM revealed a number of hollow spheres with cells with an average diameter of 56.25 nm and a mean wall thickness of 6.56 nm. CaSki cells were detected by inverted fluorescence microscopy via a layer of fluorescent green marker, and ICP-AES confirmed the distinct uptake of anti-c-Met/HGNs by each CaSki cell. Anti-c-Met/HGNs induced 38.7% of cells to stay in the G2/M phase, whereas the equivalent proportion in the control group was 19.8%. Compared with other groups, CaSki cells treated with anti-c-Met/HGNs and 5 Gy X-ray radiation exhibited a higher apoptosis rate (16.92%) and a higher early apoptotic rate (12.30%) compared with cells under other conditions (control+0 Gy: 3.16 and 1.69%; HGN+0 Gy: 3.98 and 1.94%; anti-c-Met/HGN+0 Gy: 3,47 and 1.85%; control+5 Gy: 5.35 and 3.66%; HGN+5 Gy: 7.91 and 4.06%). The anti-c-Met/HGN X-ray-treated group also evidently overexpressed caspase-3 and BCL2 associated X, apoptosis regulator. Anti-c-Met/HGN may, therefore, aid the sensitivity of radiation therapy in cervical cancer.