Advancing Radiobiology: Investigating the Effects of Photon, Proton, and Carbon-Ion Irradiation on PANC-1 Cells in 2D and 3D Tumor Models

Abstract

Introduction: Pancreatic cancer (PC) is one of the most aggressive and lethal malignancies, calling for enhanced research. Pancreatic ductal adenocarcinoma (PDAC) represents 70-80% of all cases and is known for its resistance to conventional therapies. Carbon-ion radiotherapy (CIRT) has emerged as a promising approach due to its ability to deliver highly localized doses and unique radiobiological properties compared to X-rays. In vitro radiobiology has relied on two-dimensional (2D) cell culture models so far; however, these are not sufficient to replicate the complexity of the in vivo tumor architecture. Three-dimensional (3D) models become a paradigm shift, surpassing the constraints of traditional models by accurately re-creating morphological, histological, and genetic characteristics as well as the interaction of tumour cells with the microenvironment. Materials and Methods: This study investigates the survival of pancreatic cancer cells in both 2D and spheroids, a 3D model, following photon, proton, and carbon-ion irradiation by means of clonogenic, MTT, spheroid growth, and vitality assays. Results: Our results demonstrate that carbon ions are more efficient in reducing cancer cell survival compared to photons and protons. In 2D cultures, carbon-ion irradiation reduced cell survival to approximately 15%, compared to 45% with photons and 30% with protons. In the 3D culture model, spheroid growth was similarly inhibited by carbon-ion irradiation; however, the overall survival rates were higher across all irradiation modalities compared to the 2D cultures. Carbon ions consistently showed the highest efficacy in reducing cell viability in both models. Conclusions: Our research highlights the pivotal role of 3D models in unraveling the complexities of pancreatic cancer radiobiology, offering new avenues for designing more effective and precise treatment protocols.

Keywords: 2D cell cultures; 3D cell culture models; conventional radiotherapy; hadrontherapy; pancreatic cancer; radiobiology; spheroids.

Figure 1

Survival curves of the clonogenic survival assays for PANC-1 cells after exposure to photons, protons, and C-ions. Error bars indicate ± standard deviations.

Figure 2

MTT assay results showing PANC-1 cell viability (%) at 24 h, 96 h, and 5 days post-irradiation with photons, protons, and C-ions at doses of 2, 4, and 6 Gy. Asterisks indicate statistically significant differences: p < 0.05 (*), p < 0.01 (**), p < 0.001 (***) and p < 0.0001 (****). Data are presented as mean ± standard deviation. Graphic created with Biorender.com (accessed on 28 November 2024).

Figure 3

Representative images of PANC-1 spheroids under control condition (CTRL) and after exposure to 2 Gy, 4 Gy, and 6 Gy of photons, protons, and C-ions.

Figure 4

Spheroid growth following photon, proton, and C-ion irradiation. Baseline measurement (0) represents spheroid size before irradiation. Subsequent measurements were taken at 24 h intervals, tracking growth from 24 h to 96 h post-irradiation. Data are presented as mean ± standard deviation with best-fit lines and 95% confidence intervals. Graphic created with Biorender.com.

Figure 5

Spheroid viability 5 days post-irradiation with photons, protons, and C-ions. Data are presented as mean ± standard deviation with best-fit lines and 95% confidence intervals. Graphic created with Biorender.com.