γ-Irradiation-induced cell cycle arrest and cell death in a human submandibular gland cell line: Effect of E2F1 expression

• Published in: Journal of cellular physiology Vol. 177; no. 2; pp. 264 - 273
• Main Authors: O'Connell, Anne C., Lillibridge, C. David, Zheng, Changyu, Baum, Bruce J., O'Connell, Brian C., Ambudkar, Indu S.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.11.1998
• Subjects: Adenoviridae - genetics; Calcium - metabolism; Carrier Proteins; Cell Cycle - radiation effects; Cell Cycle Proteins - biosynthesis; Cell Cycle Proteins - genetics; Cell Cycle Proteins - radiation effects; Cell Death - radiation effects; Cell Division - radiation effects; Cell Line; DNA-Binding Proteins; E2F Transcription Factors; E2F1 Transcription Factor; Gamma Rays; Humans; Intracellular Fluid - metabolism; Intracellular Fluid - radiation effects; Retinoblastoma-Binding Protein 1; Submandibular Gland - cytology; Submandibular Gland - radiation effects; Transcription Factor DP1; Transcription Factors - biosynthesis; Transcription Factors - genetics
• ISSN: 0021-9541; 1097-4652
• DOI: 10.1002/(SICI)1097-4652(199811)177:2<264::AID-JCP8>3.0.CO;2-L

This study examined the effect of γ‐irradiation (5 and 10 Gy) on the human submandibular cell line (HSG). Radiation treatment (5 Gy and 10 Gy) induced a dose‐dependent decrease in cell proliferation, with a G2/M arrest of the cell cycle, and an increase in cell death (cells with <2n DNA increased from 7% in control cells to 34% and 40% in 5 and 10 Gy irradiated cells, respectively). [Ca2+]i measurements demonstrated that the status of internal Ca2+ stores, and muscarinic receptor‐mediated Ca2+ mobilization, in irradiated cells was comparable to that in non‐irradiated cells. These data suggest that (1) irradiated HSG cells maintain normal physiology and (2) internal Ca2+ store depletion does not account for the decreased cell proliferation. To manipulate the radiation‐induced cell cycle arrest, we examined the effect of the transcription factor E2F1, which has been shown to induce cell cycle progression in HSG cells (Lillibridge and O'Connell, 1997, J. Cell. Physiol., 172:343–350). The ability of irradiated HSG cells to express and appropriately route proteins was demonstrated by using adenovirus‐mediated expression of β‐galactosidase, α1‐antitrypsin, and aquaporin‐1. Infection of HSG cells with an adenoviral vector encoding E2F1, either 12 h before or immediately following irradiation, but not post‐irradiation, induced maintenance of cells in the S phase of the cell cycle, reduced the number of cells arrested at G2/M, and decreased the rate of appearance of cells with <2n DNA. While the mechanism of irradiation‐induced cell death has not yet been confirmed, these data suggest that expression of the E2F1 gene product in HSG cells can be a useful strategy to manipulate cell cycle events and reduce the initial loss of cells due to radiation. J. Cell. Physiol. 177:264–273, 1998. © 1998 Wiley‐Liss, Inc. This article is a US government work, and as such, is in the public domain in the United States of America.