5187

PER1

period circadian clock 1;PER1;period circadian clock 1

Period, drosophila, homolog of|circadian clock protein PERIOD 1|circadian pacemaker protein RIGUI|hPER1|period circadian protein homolog 1|period homolog 1

17p13.1

protein-coding

To explore the mechanism of the disruption of circadian rhythm in breast cancer, we examined the expression of nine circadian genes in 53 newly diagnosed breast cancers by immunohistochemical staining, mutational analysis, and methylation analysis of the promoter of circadian genes. Our results showed that 37 of the 53 breast cancer tissues had hypermethylation on the promoters of PER1, PER2, CRY1, or BMAL1. Twenty-five out of 53 paired noncancerous (normal) tissues had methylation on the promoter of PER1 or CRY1. Our results indicated a higher frequency of concurrent methylation of PER1 and CRY1 promoters in cancerous and normal tissues. Promoter methylation of the PER1 correlates with c-erbB2 immunohistochemical reaction of > or = 2+ (p = 0.012) and has a strong inverse correlation with estrogen receptor positivity (p = 0.016). We further analyzed the patterns of circadian gene expression by immunohistochemical methods and found that homogeneous expression of PER2 or BMAL1 is significantly associated with lymph node metastasis and poor prognosis. PER2 heterogeneous expression correlates with <2+ c-erbB2 immunohistochemical reaction. Heterogeneous expression of CLOCK is associated significantly with 3-year survival. In conclusion, the expression pattern of circadian genes might be a biomarker for the prognosis of breast cancer.

Circadian rhythms are daily oscillations in various biological processes, generated by the feedback loops of eight core circadian genes: Period1 (Per1), Period2 (Per2), Period3 (Per3), Cryptochrome1 (Cry1), Cryptochrome2 (Cry2), Clock, Bmal1 and Casein Kinase I epsilon (CKIepsilon). Recent studies have suggested that circadian genes participate in the growth and development of various cancers. This study examined the relations of circadian gene expression to clinicopathological factors and outcomes in patients with colorectal cancer. We studied surgical specimens of cancer tissue and adjacent normal mucosa obtained from 202 patients with untreated colorectal cancer. The relative expression levels of the circadian genes in the specimens were measured by quantitative real-time, reverse-transcription polymerase chain reaction. expression of the Clock gene and the CKIepsilon gene in cancer tissue were significantly higher compared to that in adjacent normal mucosa. expression of the Per1 and Per3 genes in cancer tissue was significantly lower compared to that in adjacent normal mucosa. Analysis of the relations between clinicopathological features and expression of the eight circadian genes in cancer tissue showed that high expression of the Bmal1 gene and low expression of the Per1 gene correlated with liver metastasis. On analysis of the relations between outcomes and gene expression, high expression of the Per2 gene was associated with significantly better outcomes than low expression of the Per2 gene. Overexpression of the Bmal1 gene and reduced expression of the Per1 gene may thus be useful predictors of liver metastasis. Moreover, reduced expression of the Per2 gene may be a predictor of outcomes in patients with colorectal cancer.

Circadian rhythms are daily oscillations in various biological processes, generated by the feedback loops of eight core circadian genes: Period1 (Per1), Period2 (Per2), Period3 (Per3), Cryptochrome1 (Cry1), Cryptochrome2 (Cry2), Clock, Bmal1 and Casein Kinase I epsilon (CKIepsilon). Recent studies have suggested that circadian genes participate in the growth and development of various cancers. This study examined the relations of circadian gene expression to clinicopathological factors and outcomes in patients with colorectal cancer. We studied surgical specimens of cancer tissue and adjacent normal mucosa obtained from 202 patients with untreated colorectal cancer. The relative expression levels of the circadian genes in the specimens were measured by quantitative real-time, reverse-transcription polymerase chain reaction. expression of the Clock gene and the CKIepsilon gene in cancer tissue were significantly higher compared to that in adjacent normal mucosa. expression of the Per1 and Per3 genes in cancer tissue was significantly lower compared to that in adjacent normal mucosa. Analysis of the relations between clinicopathological features and expression of the eight circadian genes in cancer tissue showed that high expression of the Bmal1 gene and low expression of the Per1 gene correlated with liver metastasis. On analysis of the relations between outcomes and gene expression, high expression of the Per2 gene was associated with significantly better outcomes than low expression of the Per2 gene. Overexpression of the Bmal1 gene and reduced expression of the Per1 gene may thus be useful predictors of liver metastasis. Moreover, reduced expression of the Per2 gene may be a predictor of outcomes in patients with colorectal cancer.

Period1 (PER1) is an important core clock gene, which regulates normal cell proliferations and physiological rhythms of human beings. Recent studies have showed aberrant expressions and altered rhythms of PER1 were highly correlated to the carcinogenesis and development of malignant tumors. However, there is no study on the correlation of aberrant expressions and altered rhythms of PER1 with the growth, proliferation and metastasis of buccal squamous cell carcinoma (BSCC). In this study, PER1 and MMP-2 expression in the cancerous and adjacent noncancerous tissues of 38 patients with BSCC and its correlations with patients' clinical pathologic characteristics were investigated. A mouse model of BSCC was also established and mice were sacrificed at 4 different time points in a period of 24 hours. Xenografted tumor weight, proliferation index (PI), and mitotic index (MI) of tumors in the 4 time groups were detected. Results showed that PER1 expression was significantly down-regulated in cancerous tissues of patients with BSCC (P<0.05). PER1 expression was significantly down-regulated in patients of T3 approximately T4 staging and those with lymph node metastasis compared to that of T1 approximately T2 staging and those without lymph node metastasis (P<0.05), respectively. PER1 mRNA expression, MI and tumor weight had significant differences among the 4 time groups, which PI all confirmed to circadian rhythms. MI, PI, MMP-2 mRNA and tumor weight had negative correlation with PER1 mRNA expression. Peak value of PER1 mRNA expression and trough values of MI, PI and tumor weight all appeared in middle activity phase, whereas trough value of PER1 mRNA expression and peak values of MI, PI and tumor weight all occurred in middle rest phase. Our study suggested that aberrant expression of PER1 had significant correlation with the growth, proliferation and metastasis of BSCC and it might act as an anti-oncogene.