Knockdown of SOX12 expression inhibits the proliferation and metastasis of lung cancer cells

Sex determining region Y-box protein 12 (SOX12) plays an important role in the tumorigenesis of hepatocellular carcinoma. The involvement of SOX12 in human lung cancer is not well-understood. The aim of the current study was to explore the expression pattern and function of SOX12 in lung cancer. SOX12 expression in lung cancer tissues was elevated as assessed by analyzing The Cancer Genome Atlas (TCGA) lung cancer cohort and real-time PCR data of our own cohort. We found that SOX12 mRNA expression was up-regulated in 83.3% (75/ 90) of the lung cancer tissues in comparison with paired normal tissues. Moreover, high SOX12 expression predicted reduced overall survival. We also found that knockdown of SOX12 in SPC-A-1 and A549 cells impaired lung cancer cell proliferation, migration and invasion in vitro, but promoted lung cancer cell apoptosis. In vivo tumorigenesis experiments showed that inhibition of SOX12 expression significantly suppressed the growth of xenograft tumors. Finally, the mRNA and protein levels of cell growth (PCNA and Cyclin E), apoptosis (Bcl-2 and Bax), invasion (matrix metalloproteinase-9) and epithelial-mesenchymal transition (EMT; Twist1 and E-cadherin) related moderators were affected by SOX12 knockdown. Chromatin immunoprecipitation assays showed that Cyclin E and Twist1 were direct transcriptional targets of SOX12. Taken together, our study suggests that SOX12 functions as an oncogenic molecule during the development of human lung cancer.