Gene expression profile upon TNF-a stimulation, forced expression of NICD, or TNF-a stimulation under forced expression of NICD, in human colon carcinoma-derived LS174T cells

A human colon carcinoma-derived cell line LS174T was modified to overexpress NICD, intracellular domain of Notch1, upon doxycycline addition (designated as LS174T-tetON-NICD cells), using the T-rex system (Invitrogen). We have previously shown that these cells can overexpress NICD under the control of CMV promoter (Okamoto R et al, Am J Physiol, 296(1):G23-35, 2009), and the amont of the overexpressed NICD protein reaches to the maximal level in early as 3 hours from doxycycline addition (100ng/ml), which persists for up to 24 hours. In the present experiment, LS174T-tetON-NICD cells were treated with recombinant human TNF-a (50ng/ml) alone, doxycycline alone (100ng/ml), co-treated by both TNF-a and doxycycline, or left untreated (Control) for 24 hours, and subjected for analysis. Experiment was done using a modified sub-line of LS174T cell (LS174T-tetON-NICD cells), in which overexpression of NICD can be induced by a Doxycycline dependent manner. Four-condition experiment, Control vs. TNF-a stimulation, Control vs Doxycycline addition (NICD overexpression) and Control vs TNF-a stimulation+Doxycycline addition (NICD overexpression). Biological replicates: One for each condition, independently grown and harvested. One replicate per array.