Low Expression of Circadian Rhythm Protein PER1 and CRY1 in Gastric Cancer

Period (Per) and Cryptochrome (Cry) are important clock-controlled genes, disturbing their transcription will induce over-activity of carcinogenesis and increase the incidence and prognosis of various cancers. However, the expressions of PER1 and CRY1 in gastric cancer (GC) are still few understood. In this study, the expressions of PER1 and CRY1 in cancerous and noncancerous tissues from GC patients were detected by IHC and the IHC sections were scored. The IHC results showed that the expressions of PER1 and CRY1 were reduced in cancerous tissues compared with noncancerous tissues. Moreover, their expressions were both significantly associated with the location of tumor, histological differentiation, lymph node metastasis, distant metastasis, depth of invasion and TNM stage. Meanwhile, down-regulated PER1 and CRY1 expressions were dramatically observed in cancers with deep invasion, good differentiation and more advanced stages. Furthermore, the expression of PER1 was positively correlated with the expression of CRY1 (r = 0.828, P < 0.01). Kaplan-Meier analysis showed patients with higher PER1 and CRY1 expressions had a longer survival time than those with lower expression. Univariate and multivariate analysis demonstrated that cell differentiation levels and TNM stage were independent prognostic factors. PER1 and CRY1 may play important roles in the development, invasion and prognosis of GC.