Abstract: Objective To investigate the radiosensitivity enhancement and possible mechanism of nano Fe3O4／C225 complex on human colorectal cancer LoVo cells. Methods In vitro inhibition rates of cell proliferation at 24h after treatment with different concentrations （0， 3.125， 6.25， 12.5， 25， 50， 100 mg／mL） of nano Fe3O4／C225 complex were determined by MTT. According to the experimental protocol， the below experiments were carried out in irradiation group，C225+irradiation group and complex+irradiation group. The colony formation assay was employed to observe the surviving fraction （SF） of three groups after X-ray irradiation of 0， 2， 4， 6， 8， 10Gy. The cell cycle of three groups at 24h after X-ray irradiation of 4Gy was measured by flow cytometry. Western blotting was employed to measure the protein level of epidermal growth factor receptor （EGFR） and p-P38, p-Akt in the related of signaling pathway.
ResultsThe proliferation inhibition rate of LoVo cells gradually increased with the increasing concentration of Fe3O4／C225 complex ranging from 3.125 to 100 mg／L. The proliferation inhibition rates were 0％， （8.950± 0.086）％， （14.760±0.011）％， （29.860±0.001）％，（41.750±0.017）％， （59.770±0.010）％ and （78.710±0.017）％ at the concentrations of 0， 3.125， 6.25， 12.5， 25， 50， 100mg／mL with statistically significant differences （P＜0.05）.Compared with irradiation group and C225+irradiation group， there were lower SF， percentage of S cells and protein levels of p-Akt，EGFR and higher percentages of G0／G1 and G2／M and protein level of p-P38 in complex+irradiation group with statistically significant differences （P＜0.05）. Conclusion Nano Fe3O4／C225 complex could inhibit the proliferation of LoVo cells with radiosensitizing effect possibly via the arrest at the G0／G1 phase and inhibition of EGFR signaling pathways.