LIFE01200604005 Shri Somnath Ghosh - Homi Bhabha National ...

CHAPTER 3
RESULTS
up-regulation of p21 (Fig.3.4.3.1 C and D, Lane, 4). The expression of p53 gene in these cells
was significantly lower than irradiated cells as well as bystander cells. The cells cultured in the
presence of medium derived from unirradiated cells did not show up-regulation either p53 or p21
gene expression (Fig.3.4.3.1 C and D, Lane 5).
3.4.3.2 NO production in irradiated and bystander cells
Since the expressions of iNOS gene was significantly upregulated in irradiated and bystander
cells (Fig.3.4.3.1B, Lane 2 and 3), it was of interest to look for NO production in these cells. NO
production was found to be significantly enhanced in irradiated cells and bystander cells as
compared to that in unirradiated control cells (Fig. 3, Lane 2 and 3). The NO production in the
cells cultured in presence of only irradiated medium or medium derived from unirradiated cells
was found to be similar to that in unirradiated cells (Fig.3.4.3.2, Lane 4 and 5).
3.4.3.3 DNA damage in irradiated and bystander cells
Damage to cellular DNA was expressed as tail length (Fig.3.4.3.3 A), per cent DNA in tail
(Fig.3.4.3.3 B), Olive tail moment (Fig.3.4.3.3 C) and Tail moment (Fig.3.4.3.3 D). The DNA
damage was significantly higher in irradiated EL-4 cells as compared to that in unirradiated cells
(Fig.3.4.3.3, A, B, C, D, Lane 2). The cells cultured in the presence of medium derived from
irradiated cells also showed a significantly higher DNA damage as compared to the unirradiated
control cells (Fig.3.4.3.3, A, B, C, D, Lane 3). However, the cells that had received only
irradiated medium or medium from unirradiated control cells did not show any increase in DNA
damage as compared to that in unirradiated control (Fig.3.4.3.3, A, B, C, D, Lane 4 and 5).
173