LIFE01200604005 Shri Somnath Ghosh - Homi Bhabha National ...

CHAPTER 3
RESULTS
3.4.4 Bystander effect in dissimilar cells (EL-4 Vs RAW 264.7)
Having confirmed the existence of bystander signaling between similar cells (EL-4 Vs EL-4), the
work was extended to determine if bystander effects can be demonstrated between different cell
type (RAW 264.7 and EL-4) and whether the state of stimulation of macrophages (RAW 264.7)
affects bystander response. The expression of NF-κB as well as iNOS genes were significantly
upregulated in unirradiated EL-4 cells that had received medium from LPS stimulated and
irradiated RAW 264.7 cells (Fig. 3.4.4a, Compare Lane, 2 and Lane 1); but the expression of
NF-κB was not altered in the cells that had received medium from either irradiated RAW 264.7
cells or unstimulated RAW 264.7 cells (Fig.3.4.4a, Compare Lane, 3 and 5 Vs Lane 1), however,
the expression of iNOS was down regulated in the above groups. The EL-4 cells cultured in the
presence of medium derived from LPS stimulated RAW 264.7 cells showed only marginal
upregulation of iNOS gene but not NF-κB gene (3.4.4a, Compare Lane 4 and Lane 1).
DNA damage in the above groups of EL-4 cells cultured 2 h after exposure to different
conditioned media was significantly higher in unirradiated EL-4 cells that had received medium
from LPS stimulated and irradiated RAW 264.7 cells (Fig.3.4.4b, Compare Lane, 2 and Lane 1).
However, the cells that had received medium from irradiated RAW 264.7 cells, LPS stimulated
RAW 264.7 cells or unstimulated RAW 264.7 cells did not show any increase in DNA damage
(Fig.3.4.4b, Lane, 3, 4 and 5).
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