Notch1 Signaling Regulates the Aggressiveness of Differentiated Thyroid Cancer and Inhibits SERPINE1 Expression

To identify novel down-stream effectors of Notch1 signaling, we have employed cDNA microarray expression profiling as a discovery platform. Human follicualr thyroid carcinoma cell line FTC236 was engineered with tet-on inducible system to establish a stable cell line. The stable cell line FTC236-Notch1 showed robust inducibility with doxycycline, which triggers the expression of Notch1 intracellular domain (NICD). The mRNA samples from FTC236-Notch1 cells with or without doxycline treamtment were analyzed in this assay. Top 50 gene sequences were identified as of the most significance which distinguished between doxycycline treated samples and control samples. Expression of SERPINE1, a down-regulated gene duing Notch1 activation from this signature, was quantified in the same RNA samples by real-time PCR. The protein level was further confirmed by Western blot that restoration of NICD inhibits the expression of SERPINE1. NICD induced gene expression in human follicular thyroid cancer cell line was measured at 48 hours after exposure to doses of 0, and 1 ug/mL of doxycycline. Three independent experiments were performed at separate time.