Revolutionizing radiotherapy: gold nanoparticles with polyphenol coating as novel enhancers in breast cancer cells-an in vitro study

Abstract

Breast cancer is the most common cancer among women, with over 1 million new cases and around 400,000 deaths annually worldwide. This makes it a significant and costly global health challenge. Standard treatments like chemotherapy and radiotherapy, often used after mastectomy, show varying effectiveness based on the cancer subtype. Combining these treatments can improve outcomes, though radiotherapy faces limitations such as radiation resistance and low selectivity for malignant cells. Nanotechnologies, especially metallic nanoparticles (NPs), hold promise for enhancing radiotherapy. Gold nanoparticles (AuNPs) are particularly notable due to their high atomic number, which enhances radiation damage through the photoelectric effect. Studies shown that AuNPs can act as effective radiosensitizers, improving tumor damage during radiotherapy increasing the local radiation dose delivered. Traditional AuNPs synthesis methods involve harmful chemicals and extreme conditions, posing health risks. Green synthesis methods using plant extracts offer a safer and more environmentally friendly alternative. This study investigates the synthesis of AuNPs using Laurus nobilis leaf extract and their potential as radiosensitizers in breast carcinoma cell lines (MCF-7). These cells were exposed to varying doses of X-ray irradiation, and the study assessed cell viability, morphological changes and DNA damage. The results showed that green-synthesized AuNPs significantly enhanced the therapeutic effects of radiotherapy at lower radiation doses, indicating their potential as a valuable addition to breast cancer treatment.

Fig. 1

Set-up irradiation with Elekta Precise linear accelerator on petri dishes (white arrow)

Fig. 2

A Axial and D sagittal images of the dose distribution in the sample positioned between the two water-equivalent bases; B 3D image of the housing set-up; C view from the gantry (Beam Eye View – BEV)

Fig. 3

Representative TEM images of green AuNPs acquired at two different magnifications a, b. XRD pattern c and UV–vis spectra d of green AuNPs

Fig. 4

ATR-FTIR spectrum of Laurus nobilis leaves extract (a); ATR-FTIR spectra of green AuNPs before (black trace) and after 2.67 Gy (blue trace) of irradiation (b)

Fig. 5

a Percentage of viability of non-irradiated MCF-7 cells treated with different concentrations of green AuNPs (0.23, 0.46, 0.9, 1.8, 3.7, 7.5, 15 and 30 μg/mL) for 72 h. Cytotoxic activity for each sample was normalized to the CTRL (untreated) cells represented by the first column of the bar graph. b Percentage of viability for CTRL (untreated) MCF-7 cells irradiated with various radiation doses (2.67, 4, 6, 8 and 10 Gy) 48 h after seeding and analyzed 24 h post- irradiation, resulting in a total incubation period of 72 h. Cytotoxic activity for each sample was normalized to the CTRL (untreated) cells represented by the first column of the bar graph

Fig. 6

Viability of MCF-7 cells incubated with different concentrations of green AuNPs (0.23, 0.46, 0.9, 1.8, 3.7, 7.5, 15 and 30 μg/mL), followed by irradiation with varying doses (2.67, 4, 6, 8 and 10 Gy) 48 h after incubation and analyzed with MTT assay 24 h post-irradiation, for a total incubation period of 72 h. All data were normalized on the CTRL (untreated) sample, indicated on the y-axis by the percentage viability reference value of 100% (black dashed line)

Fig. 7

Confocal images of actin fibers (green) and nuclei (blue) of MCF-7 cells acquired under different conditions: a CTRL (MCF-7 untreated); b MCF-7 incubated with green AuNPs (0.46 μg/mL) (not irradiated); c CTRL irradiated with 2.67 Gy X-rays dose; d MCF-7 incubated with green AuNPs (0.46 μg/mL) and irradiated with 2.67 Gy X-rays dose; e CTRL irradiated with 8 Gy X-rays dose; f MCF-7 incubated with green AuNPs (0.46 μg/mL) and irradiated with 8 Gy X-rays dose

Fig. 8

Analysis of actin coherency a; nucleus circularity b and nucleus to cytoplasm ratio of MCF-7 cells c performed on 30 cells

Fig. 9

a–f, Petri dishes from the clonogenic assay of MCF-7 cells incubated with 0.46 μg/mL green AuNPs, irradiated and stained after 14 days. The irradiations corresponded to: a CTRL MCF-7 (untreated) not irradiated, b 2.67 Gy of X-rays dose, c 4 Gy of X-rays dose, d 6 Gy of X-rays dose, e) 8 Gy of X-rays dose, f 10 Gy of X-rays dose. g (△) Survival curves of MCF-7 incubated with 0.46 μg/mL green AuNPs concentration, irradiated with doses ranging from 2.67 to 10 Gy after 48 h from incubation, and immediately stained after 3 days post-irradiation (y = −0.0869 x²−0.094 x; R² = 0.9944); (●) survival curves of MCF-7 incubated with 0.46 μg/mL green AuNPs concentration, irradiated with doses ranging from 2.67 to 10 Gy after 48 h from incubation, and delayed stained after 14 days post-irradiation (y = − 0.0973 x²−0.3236 x; R² = 0.9547). h) (●) Survival curves of MCF-7 incubated with 0.46 μg/mL green AuNPs concentration, irradiated with doses ranging from 2.67 to 10 Gy after 48 h from incubation, and delayed stained after 14 days post-irradiation (y = −0.0973 x²−0.3236 x; R² = 0.9547); ( ×) survival curve of CTRL MCF-7 (untreated) irradiated with doses ranging from 2.67 to 10 Gy after 48 h from seeding, and stained after 14 days post-irradiation (y = −0.0256 x²−0.2391 x; R² = 0.9919).

Fig. 10

Representative images of X-rays and green AuNPs on DNA damage in MCF-7 obtained by comet assay a CTRL (MCF-7 untreated); b MCF-7 incubated with green AuNPs (0.46 μg/mL) (not irradiated); c CTRL irradiated with 2.67 Gy X-rays dose; d MCF-7 incubated with green AuNPs (0.46 μg/mL) and irradiated with 2.67 Gy X-rays dose; e CTRL irradiated with 8 Gy X-rays dose; f MCF-7 incubated with green AuNPs (0.46 μg/mL) and irradiated with 8 Gy X-rays dose. DNA damage was evaluated by g tail length (μm) and h head intensity (%). Values shown are means from 100 randomly selected comet images of each sample. As positive control (P) cells were incubated with 500 μM H₂O₂ (data not shown). Data are reported as mean ± SD from three independent experiments; *p < 0.05 compared with control (MCF-7 untreated) (n = 3)