The transcriptomic effect of induced LRIG1 expression in NPC cells

As LRIG1 known to be a negative regulator of EGFR, we postulate that restored LRIG1 expression will change the transcription profile through the regulation of EGFR as well as its downstream signal cascades. Thus, we conducted a time-course microarray study to examine the effect of restored LRIG1 expression in NPC line, TW01-LG1/a, which the LRIG1 expression is under the control of a promoter with Doxycycline response element. We established stable transfectants of the LRIG1 gene in the TW01 cells which the expression of LRIG1 protein was barely detectable. To control the expression of LRIG1, the coding sequences were placed under the control of a promoter with doxycycline (Dox)-response element using the Tetoff system. Thus the LRIG1 expression could be turn on by removing Dox from the culture medium. Cellular total RNA were harvested along a time course of 12, 24, 36, and 48 hr following LRIG1 turn on expression, and then subjected to exon array analysis (Affymatrix Human Gene 1.0 ST), using the LRIG1 non-expressing sample (with Dox) as control for all comparison. For each time-point, a biological replicate was included.