Characterization of cell-cycle progression and growth of WB-F344 normal rat liver epithelial cells following gamma-ray exposure

✍ Scribed by Bogdan I. Gerashchenko; Edouard I. Azzam; Roger W. Howell

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 424 KB
• Volume: 61A
• Category: Article
• ISSN: 0196-4763
• DOI: 10.1002/cyto.a.20065

✦ Synopsis

Abstract

Background

Apparently normal rat liver epithelial cells (WB‐F344) have been widely used in studies pertaining to carcinogenesis. Ionizing radiation, a well known carcinogen, is known to perturb cell‐cycle progression in a dose‐dependent manner, thereby causing delay in cell proliferation. However, for WB‐F344 cells, there is a paucity of such data, which are of substantial importance in understanding their radiation response. Here, the distribution of phases in the cell‐cycle and the proliferation ability of WB‐F344 cells are characterized at various time points after the cells have been irradiated with different doses of γ‐rays.

Methods

After WB‐F344 cells reached 100% confluence, they were trypsinized and suspended at 3.5 × 10^5^ cells/ml in culture medium. Cells were irradiated in suspension with ^137^Cs γ‐rays at doses from 1–10 Gy. After irradiation, 1 × 10^5^ cells were plated into 60 × 15‐mm culture dishes and incubated at 37°C, with 2% CO~2~ and 98% air. At 12, 24, 36, 48, and 60 h postirradiation, cells were harvested, counted, and subjected to flow cytometric cell‐cycle analysis.

Results

Growth curves of WB‐F344 cells irradiated with γ‐rays started to separate at 36 h postirradiation. By 60 h postirradiation, the growth curves for each of the 10 absorbed doses were distinctly separated. Drastic redistributions of control and irradiated cells within G~0~/G~1~‐, S‐, and G~2~/M‐phases of the cell cycle were observed during the first 36 h of cell growth. At each time point postirradiation, cell‐cycle phase profiles of irradiated cells were altered in a dose‐dependent manner. In general, there was a strong correlation between the percentage of G~2~/M‐phase cells and absorbed dose, with the exception of 24 h postirradiation. The percentage of G~2~/M‐phase cells increased as a function of time postirradiation, suggestive of delays in the passage of cells through the G~2~ cell‐cycle checkpoint.

Conclusions

This work provides a general description of cell cycle redistribution and repopulation kinetics of WB‐F344 cells at various times postirradiation of quiescent cells that were subsequently allowed to proliferate. In general, growth inhibition and delays in progression through G~2~/M‐phase correlated well with radiation dose. These data should be of considerable significance in the design of experiments that examine the radiation response of these cells. © 2004 Wiley‐Liss, Inc.