Transcription Factor YY1 Modulates Lung Cancer Progression by Activating lncRNA-PVT1.

Lung cancer is the leading cause of cancer-related death worldwide. Despite the advancement in surgery and chemotherapy, the prognosis of patients with advanced lung cancer is still poor. Yin Yang-1 (YY1) is a multifunctional transcription factor that exhibits positive and negative control on a large number of cellular and viral genes. In this study, we showed that the expression of YY1 is upregulated in lung cancer tissues as compared to adjacent normal tissues. Patients with higher expression of YY1 had larger tumor size, poor differentiation, higher TNM stage, and lymph node metastasis. Ectopic expression of YY1 in lung cancer cells promoted cell proliferation and invasion. Inversely, siRNA-mediated silencing of YY1 inhibited cell proliferation and induced apoptosis. These results suggested that YY1 may function as an oncogene in lung cancer. Moreover, through luciferase reporter assay, electrophoretic mobility shift assay, and chromatin immunoprecipitation assay, we showed that YY1 could directly bind to the promoter region of (long noncoding RNA-plasmacytoma variant translocation 1 [lncRNA-PVT1]) and activated its transcription through the consensus YY1 motif. Knockdown of the expression of YY1 reduced cell proliferation in vivo, consistent with the results obtained from silencing the expression of YY1 in lung cancer cells. Collectively, our study showed a critical role of YY1 in the regulation of tumorigenesis, partly through its downstream target PVT1.