Aberrant expression of Per1, Per2 and Per3 and their prognostic relevance in non-small cell lung cancer

The objective of the current study was to investigate the expression pattern and clinicopathological significance of Period1 (Per1), Period2 (Per2) and Period3 (Per3) in patients with non-small cell lung cancer (NSCLC). In 130 archived NSCLC tissues, the positive rate of Per1 (86/130, 66.2%), Per2 (77/130, 59.2%) and Per3 (82/130, 63.1%) were reduced in human lung cancer samples compared with adjacent normal lung tissues (Per1, 119/130, 91.5%; Per2, 115/130, 88.5%; Per3, 121/130, 93.1%), as measured by immunohistochemical staining. Loss of Per1 was correlated with poor differentiation (P < 0.001), tumor status (P=0.04), high p-TNM stage (P < 0.001) and lymph node metastasis (P=0.045). The similar tendencies were also found in the correlation of the expression of Per2 and Per3 with clinicopathological factors. In addition, a significant correlation was found between Per1 and Per2 (P < 0.001) in 130 cases of NSCLC. Similarly, a significant correlation was found between Per2 and Per3 (P=0.045). Patients with lower expression of Per1, Per2 and Per3 had a shorter survival time than those with higher expression. These results indicate that loss of Per may promote tumor progression in NSCLC, and may serve as a novel prognostic biomarker of NSCLC.