Enhanced Cytotoxicity against a Pancreatic Cancer Cell Line Combining Radiation and Gold Nanoparticles

Abstract

The present work consisted of an exploratory study aiming to evaluate in vitro the potential of AuNPs during Radiation Therapy (RT) in human pancreatic adenocarcinoma cells. AuNPs coated with hyaluronic and oleic acids (HAOA-AuNPs) or with bombesin peptides (BBN-AuNPs) were used. AuNPs were characterized by Atomic Force Microscopy (AFM) and Dynamic Light Scattering. BxPC-3 tumor cells were irradiated with a 6 MV X-rays beam, in the absence or presence of AuNPs. AFM showed that HAOA-AuNPs and BBN-AuNPs are spherical with a mean size of 83 ± 20 nm and 49 ± 12 nm, respectively. For RT alone, a reduction in cell viability of up to 33 ± 12% was obtained compared to the control (p ≤ 0.0001). HAOA-AuNPs alone at 200 and 400 μM showed a reduction in cell viability of 20 ± 4% and 35 ± 4%, respectively, while for BBN-AuNPs, at 50 and 200 μM, a reduction in cell viability of 25 ± 3% and 37 ± 3% was obtained, respectively, compared to the control (p < 0.0001). At 72 h post-irradiation, a decrease in cell viability of 26 ± 3% and 22 ± 2% between RT + HAOA-AuNPs at 400 μM and RT + BBN-AuNPs at 50 μM, compared to RT alone, was obtained (p < 0.004). The combination of RT with AuNPs led to a significant decrease in cell viability compared to the control, or RT alone, thus representing an improved effect.

Keywords: cell viability; gold nanoparticles; megavoltage radiation therapy; pancreatic cancer.

Figure 1

(a) Computer tomography (CT) image of the phantom and (b) radiation dose distribution used for irradiation of BxPC-3 cells obtained in the treatment planning system Eclipse. The isodoses show that all cells were irradiated with the same radiation dose; (c) a posterior 6 MV beam from a Varian Edge linear accelerator was used. Each 96-well plate was placed at the isocenter at a 10 cm depth of the phantom (indicated by the lasers).

Figure 2

3D Atomic Force Microscopy images with corresponding cross-section profiles for the two AuNP formulations: (a) HAOA-AuNPs and (b) BBN-AuNPs.

Figure 3

Cell viability of BxPC-3 cell line 24, 48, and 72 h after irradiation with doses ranging from 2 to 10 Gy (without AuNPs). Cells not irradiated were considered the control group. ** p < 0.01, **** p < 0.0001 compared to control at the same incubation time.

Figure 4

Cell viability of BxPC-3 cell line 48 and 72 h after photon beam irradiation, with radiation doses ranging from 2 to 5 Gy, and with HAOA-AuNPs and BBN-AuNPs with concentrations ranging from 50 to 400 μM compared to non-treated cells (0 Gy). * p < 0.05, ** p < 0.01, *** p < 0.001, and **** p < 0.0001 compared to control, i.e., non-treated cells. ## p < 0.01, ### p < 0.001, and #### p < 0.0001 compared to RT alone at the same radiation dose. $$ p < 0.01, $$$ p < 0.001, and $$$$ p < 0.0001 compared to AuNPs alone at the same concentration.

Figure 5

Results of the coefficient of treatment interaction (CI) for the NPs tested 72 h post-irradiation. It was considered that there was a synergy between the two treatments when CI < 1 while, for CI = 1, the effect was considered additive and, for CI > 1, the effect was considered antagonistic [38]. Doses of radiation from 2 to 5 Gy were delivered with concentrations of AuNP of 50 to 400 μM of HAOA and BBN-AuNP.