Recent studies demonstrated that cancer stem cells (CSCs) have higher
tumorigenesis properties than those of differentiated
cancer cells and that transcriptional factor-SOX2 plays a vital role in maintaining the unique properties of CSCs; however, the function and underlying mechanism of SOX2 in
carcinogenesis of
lung cancer are still elusive. This study applied immunohistochemistry to analyze the expression of SOX2 in human lung tissues of normal individuals as well as patients with
adenocarcinoma,
squamous cell carcinoma, and large cell and
small cell carcinoma and demonstrated specific overexpression of SOX2 in all types of
lung cancer tissues. This finding supports the notion that SOX2 contributes to the
tumorigenesis of
lung cancer cells and can be used as a diagnostic probe. In addition, obviously higher expression of oncogenes c-MYC, WNT1, WNT2, and NOTCH1 was detected in side population (SP) cells than in non-side population (NSP) cells of human
lung adenocarcinoma cell line-A549, revealing a possible mechanism for the tenacious tumorigenic potential of CSCs. To further elucidate the function of SOX2 in
tumorigenesis of
cancer cells, A549 cells were established with expression of
luciferase and
doxycycline-inducible
shRNA targeting SOX2. We found silencing of SOX2 gene reduces the tumorigenic property of A549 cells with attenuated expression of c-MYC, WNT1, WNT2, and NOTCH1 in xenografted NOD/SCID mice. By using the
RNA-Seq method, an additional 246 target cancer genes of SOX2 were revealed. These results present evidence that SOX2 may regulate the expression of oncogenes in CSCs to promote the development of human
lung cancer.