LIFE01200604005 Shri Somnath Ghosh - Homi Bhabha National ...

CHAPTER 3
RESULTS
signaling factors were involved in bystander response. The response was looked at in the
presence of cPTIO or L-NAME. L-NAME was washed out before irradiation so that the
bystander cells are not exposed to L-NAME and iNOS is inhibited only in the irradiated cells.
The addition of cPTIO, which scavenges the NO released in the medium, did not affect the
expression of iNOS gene if the bystanding cell was of same origin, although NF-κB was
somewhat inhibited (Fig.3.4.5a, Compare Lane 5 and Lane 3). The addition of L-NAME, which
inhibits the iNOS in the irradiated cells, completely inhibited the bystander response in the EL-4
cells (Fig.3.4.5a, Compare Lane 4 and Lane 3). However both L-NAME and cPTIO inhibited
the expression of NF-κB and iNOS in the bystander EL-4 cells if the medium was from LPS
stimulated and irradiated RAW 264.7 cells (Fig.3.4.5a, Lane 6 and 7) i.e. the cell type was
different, indicating that the bystander response was dependent on the cells type and the state of
stimulation of the irradiated cells.
The DNA damage was significantly higher in irradiated as well as in bystander cells (Fig.3.4.5b,
Lane 2 and 3) as compared to the unirradiated control. However, the unirradiated EL-4 cells that
had received medium either from L-NAME treated and irradiated EL-4 cells or from LPS
stimulated, L-NAME treated and irradiated RAW 264.7 cells did not show any increase in DNA
damage as compared to that in unirradiated control (Fig.3.4.5b, Lane 4 and 6). Similarly the
unirradiated EL-4 cells that had received medium either from cPTIO treated and irradiated EL-4
cells or from LPS stimulated, cPTIO treated and irradiated RAW 264.7 cells did not show any
increase in DNA damage as compared to that in unirradiated control (Fig.3.4.5b, Lane 5 and 7).
Neither L-NAME nor cPTIO itself had any effect on DNA damage in EL-4 cells (Fig.3.4.5b,
Lane 8 and 9).
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