INDUCED POLYPLOIDY AND SORTING OF DAMAGED DNA BY MICRONUCLEATION IN RADIORESISTANT RAT LIVER EPITHELIAL STEM-LIKE...

Area of Science:

• Cell Biology
• Radiation Biology
• Stem Cell Research

Background:

• Rat liver stem-like epithelial cells (WB-F344) possess the capacity for differentiation into hepatocyte and biliary lineages.
• Understanding the response of stem cells to radiation is crucial for regenerative medicine and cancer therapy.

Purpose of the Study:

• To investigate the cell cycle behavior and survival mechanisms of WB-F344 cells following acute X-irradiation.
• To examine the role of DNA damage, polyploidization, and self-renewal factors in the radioresistance of these stem cells.

Main Methods:

• WB-F344 cells were exposed to varying doses of X-rays (1, 5, and 10 Gy).
• Post-irradiation, cells were analyzed for nuclear morphology, DNA ploidy, and the presence of DNA lesions (γ-H2AX).
• Expression of proliferation (Ki-67) and stem cell self-renewal markers (OCT4, NANOG) was assessed via immunofluorescence staining.

Main Results:

• WB-F344 cells demonstrated significant radioresistance, with minimal apoptosis observed even at high doses.
• Irradiation induced dose-dependent cell cycle delay, polyploidization, and micronucleation.
• Micronuclei contained clusters of γ-H2AX, indicating isolated DNA damage, while OCT4 and NANOG expression increased post-irradiation.

Conclusions:

• Micronucleation may serve as a mechanism for WB-F344 cells to eliminate damaged DNA and escape cell death.
• Induced polyploidy appears to be an adaptive survival strategy, potentially involving self-renewal pathways, to facilitate tissue regeneration after radiation exposure.