PS02.047: TARGETED SILENCING OF SOX2 BY AN ARTIFICIAL TRANSCRIPTION FACTOR SUPPRESSED THE GROWTH OF ESOPHAGEAL CANCER CELLS

Background SOX2 is a transcription factor that is fundamental for early development and for the maintenance of stem cells in multiple adult tissues and also plays an important role in squamous cell differentiation. Amplification of chromosome 3q26 is the most common of the genetic alterations found in squamous cell carcinoma (SCC). SOX2 is a candidate oncogene present in this locus and amplification of SOX2 has been reported in lung and esophageal squamous cell SCC. In this study, we have developed a zinc finger-based artificial transcription factor (ATF) to selectively suppress SOX2 expression in cancer cells and termed the system ATF/SOX2. Methods We engineered the ATF using six zinc finger arrays designed to target a 19 bp site in the SOX2 distal promoter and a KOX transcriptional repressor domain. A recombinant adenoviral vector Ad-ATF/SOX2 that expresses ATF/SOX2 suppressed SOX2 at the mRNA and protein levels in esophageal SCC cells(TE1 and TE4) expressing SOX2. Results Ad-ATF/SOX2 decreased esophageal SCC cells proliferation and colony formation more effectively than the recombinant adenoviral vector Ad-shSOX2, which expresses SOX2 short hairpin RNA (shSOX2). Ad-ATF/SOX2 induced the cell cycle inhibitor CDKN1A more strongly than Ad-shSOX2. Moreover, Ad-ATF/SOX2 effectively inhibited tumor growth in a SCC xenograft mouse model. Conclusion In this study, we have shown that the targeted down-regulation of SOX2 using ATF based technologies can be used as an effective tool for the treatment of SCC in esophageal cancers that express SOX2. Our results indicate that ATF/SOX2 would lead to the development of an effective molecular-targeted therapy for esophageal SCC. Disclosure All authors have declared no conflicts of interest.