Studying ferroptosis and pyroptosis as new cell death mechanisms induced by ionizing radiation in Ehrlich solid tumor-bearing mice

Abstract

Objective: Our objective was to explore the effect of different fractionation schedule on ferroptosis and pyroptosis biomarkers as new cell death mechanisms induced by IR.

Materials and methods: This study included 40 tumor bearing mice divided into: Group I: Includes 8 untreated tumor-bearing mice. Group II: Includes 8 tumor bearing mice exposed to single dose 6 Gy of IR. Group III: Includes 8 tumor bearing mice exposed to 12 Gy in 2 fractions (2 × 6 Gy) of IR. Group IV: Includes 8 tumor bearing mice exposed to 12 Gy in 3 fractions (3 × 4 Gy) of IR. Group V: Includes 8 tumor bearing mice exposed to 8 Gy in 4 fractions (4 × 2 Gy) of IR. IL-1β, IL-18, and GSDMD-CT levels were assessed by ELISA. PTGS2 and ACSL4 expression were assessed by RT-PCR.

Results: (2 × 6 Gy) group showed the highest ACSL4 expression followed by (3 × 4 Gy), then (4 × 2 Gy) and finally 6 Gy. (2 × 6 Gy) group resulted in the highest PTGS2 expression followed by (3 × 4 Gy), then 6 Gy, and finally (4 × 2 Gy). MDA significantly increased at (2 × 6 Gy), (3 × 4 Gy), and 6 Gy groups and insignificantly increased at (4 × 2 Gy) group. Iron significantly increased at (2 × 6 Gy), (3 × 4 Gy), and (4 × 2 Gy) groups and insignificantly at 6 Gy. Glutathione was significantly decreased at (2 × 6 Gy), (3 × 4 Gy), and (4 × 2 Gy) groups and insignificantly at 6 Gy. GSDMD-CT, IL-1β, and IL-18 levels significantly reduced in tumor tissues after exposure to IR at all doses.

Conclusion: High dose per fraction regimens induce the expression of ferroptosis markers more than low dose per fraction regimen and single dose of IR. IR at all doses induces pyroptotic cell death.

Keywords: Ehrlich solid tumor; Ferroptosis; Fractionated radiation dose; Pyroptosis.