Gene Summary

Gene:CRY1; cryptochrome circadian clock 1
Aliases: PHLL1
Summary:This gene encodes a flavin adenine dinucleotide-binding protein that is a key component of the circadian core oscillator complex, which regulates the circadian clock. This gene is upregulated by CLOCK/ARNTL heterodimers but then represses this upregulation in a feedback loop using PER/CRY heterodimers to interact with CLOCK/ARNTL. Polymorphisms in this gene have been associated with altered sleep patterns. The encoded protein is widely conserved across plants and animals. Loss of the related gene in mouse results in a shortened circadian cycle in complete darkness. [provided by RefSeq, Jan 2014]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Source:NCBIAccessed: 10 March, 2017


What does this gene/protein do?
Show (18)
Pathways:What pathways are this gene/protein implicaed in?
Show (2)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 10 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Sirtuin 1
  • Genotype
  • Liver Cancer
  • Hepatocellular Carcinoma
  • Case-Control Studies
  • Genetic Predisposition
  • Transcription
  • Genetic Variation
  • ZAP-70 Protein-Tyrosine Kinase
  • Circadian Clocks
  • Stomach Cancer
  • DNA Methylation
  • RT-PCR
  • Chronic Lymphocytic Leukemia
  • Prostate Cancer
  • Messenger RNA
  • Cryptochromes
  • Immunoenzyme Techniques
  • Circadian Rhythm
  • Adenocarcinoma
  • Cancer Gene Expression Regulation
  • Gene Expression Profiling
  • Promoter Regions
  • Biomarkers, Tumor
  • ARNTL Transcription Factors
  • Young Adult
  • Breast Cancer
  • Up-Regulation
  • Gene Expression
  • Period Circadian Proteins
  • CLOCK Proteins
  • Chromosome 12
  • Transfection
  • Cell Cycle
  • Risk Factors
  • Single Nucleotide Polymorphism
  • Colorectal Cancer
  • Follow-Up Studies
  • Nuclear Proteins
  • Proto-Oncogene Proteins c-bcl-6
Tag cloud generated 10 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: CRY1 (cancer-related)

Huisman SA, Ahmadi AR, IJzermans JN, et al.
Disruption of clock gene expression in human colorectal liver metastases.
Tumour Biol. 2016; 37(10):13973-13981 [PubMed] Free Access to Full Article Related Publications
The circadian timing system controls about 40 % of the transcriptome and is important in the regulation of a wide variety of biological processes including metabolic and proliferative functions. Disruption of the circadian clock could have significant effect on human health and has an important role in the development of cancer. Here, we compared the expression levels of core clock genes in primary colorectal cancer (CRC), colorectal liver metastases (CRLM), and liver tissue within the same patient. Surgical specimens of 15 untreated patients with primary CRC and metachronous CRLM were studied. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the expression of 10 clock genes: CLOCK, BMAL1, PER1, PER2, PER3, CRY1, CRY2, CSNK1E, TIM, TIPIN, and 2 clock-controlled genes: Cyclin-D1, and WEE1. Expression levels of 7 core clock genes were downregulated in CRLM: CLOCK (p = 0.006), BMAL1 (p = 0.003), PER1 (p = 0.003), PER2 (p = 0.002), PER3 (p < 0.001), CRY1 (p = 0.002), and CRY2 (p < 0.001). In CRC, 5 genes were downregulated: BMAL1 (p = 0.02), PER1 (p = 0.004), PER2 (p = 0.008), PER3 (p < 0.001), and CRY2 (p < 0.001). CSNK1E was upregulated in CRC (p = 0.02). Cyclin-D1 and WEE1 were both downregulated in CRLM and CRC. Related to clinicopathological factors, a significant correlation was found between low expression of CRY1 and female gender, and low PER3 expression and the number of CRLM. Our data demonstrate that the core clock is disrupted in CRLM and CRC tissue from the same patient. This disruption may be linked to altered cell-cycle dynamics and carcinogenesis.

Qu F, Qiao Q, Wang N, et al.
Genetic polymorphisms in circadian negative feedback regulation genes predict overall survival and response to chemotherapy in gastric cancer patients.
Sci Rep. 2016; 6:22424 [PubMed] Free Access to Full Article Related Publications
Circadian negative feedback loop (CNFL) genes play important roles in cancer development and progression. To evaluate the effects of single nucleotide polymorphisms (SNPs) in CNFL genes on the survival of GC patients, 13 functional SNPs from 5 CNFL genes were genotyped in a cohort of 1030 resected GC patients (704 in the training set, 326 in the validation set) to explore the association of SNPs with overall survival (OS). Among the 13 SNPs, three SNPs (rs1056560 in CRY1, rs3027178 in PER1 and rs228729 in PER3) were significantly associated with OS of GC in the training set, and verified in the validation set and pooled analysis. Furthermore, a dose-dependent cumulative effect of these SNPs on GC survival was observed, and survival tree analysis showed higher order interactions between these SNPs. In addition, protective effect conferred by adjuvant chemotherapy (ACT) on GC was observed in patients with variant alleles (TG/GG) of rs1056560, but not in those with homozygous wild (TT) genotype. Functional assay suggested rs1056560 genotypes significantly affect CRY1 expression in cancer cells. Our study presents that SNPs in the CNFL genes may be associated with GC prognosis, and provides the guidance in selecting potential GC patients most likely responsive to ACT.

Mazzoccoli G, Colangelo T, Panza A, et al.
Deregulated expression of cryptochrome genes in human colorectal cancer.
Mol Cancer. 2016; 15:6 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Circadian disruption and deranged molecular clockworks are involved in carcinogenesis. The cryptochrome genes (CRY1 and CRY2) encode circadian proteins important for the functioning of biological oscillators. Their expression in human colorectal cancer (CRC) and in colon cancer cell lines has not been evaluated so far.
METHODS: We investigated CRY1 and CRY2 expression in fifty CRCs and in the CaCo2, HCT116, HT29, SW480 cell lines.
RESULTS: CRY1 (p = 0.01) and CRY2 (p < 0.0001) expression was significantly changed in tumour tissue, as confirmed in a large independent CRC dataset. In addition, lower CRY1 mRNA levels were observed in patients in the age range of 62-74 years (p = 0.018), in female patients (p = 0.003) and in cancers located at the transverse colon (p = 0.008). Lower CRY2 levels were also associated with cancer location at the transverse colon (p = 0.007). CRC patients displaying CRY1 (p = 0.042) and CRY2 (p = 0.043) expression levels over the median were hallmarked by a poorer survival rate. Survey of selected colon cancer cell lines evidenced variable levels of cryptochrome genes expression and time-dependent changes in their mRNA levels. Moreover, they showed reduced apoptosis, increased proliferation and different response to 5-fluorouracil and oxaliplatin upon CRY1 and CRY2 ectopic expression. The relationship with p53 status came out as an additional layer of regulation: higher CRY1 and CRY2 protein levels coincided with a wild type p53 as in HCT116 cells and this condition only marginally affected the apoptotic and cell proliferation characteristics of the cells upon CRY ectopic expression. Conversely, lower CRY and CRY2 levels as in HT29 and SW480 cells coincided with a mutated p53 and a more robust apoptosis and proliferation upon CRY transfection. Besides, an heterogeneous pattern of ARNTL, WEE and c-MYC expression hallmarked the chosen colon cancer cell lines and likely influenced their phenotypic changes.
CONCLUSION: Cryptochrome gene expression is altered in CRC, particularly in elderly subjects, female patients and cancers located at the transverse colon, affecting overall survival. Altered CRY1 and CRY2 expression patterns and the interplay with the genetic landscape in colon cancer cells may underlie phenotypic divergence that could influence disease behavior as well as CRC patients survival and response to chemotherapy.

Yang MY, Lin PM, Hsiao HH, et al.
Up-regulation of PER3 Expression Is Correlated with Better Clinical Outcome in Acute Leukemia.
Anticancer Res. 2015; 35(12):6615-22 [PubMed] Related Publications
BACKGROUND: Altered expression of circadian clock genes has been linked to various types of cancer. This study aimed to investigate whether these genes are also altered in acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL).
MATERIALS AND METHODS: The expression profiles of nine circadian clock genes of peripheral blood (PB) leukocytes from patients with newly-diagnosed AML (n=41), ALL (n=23) and healthy individuals (n=51) were investigated.
RESULTS: In AML, the expression of period 1 (PER1), period 2 (PER2), period 3 (PER3), cryptochrome 1 (CRY1), cryptochrome 2 (CRY2), brain and muscle aryl hydrocarbon receptor nuclear translocator (ARNT)-like 1 (BMAL1), and timeless (TIM) was significantly down-regulated, while that of CK1ε was significantly up-regulated. In ALL, the expression of PER3 and CRY1 was significantly down-regulated, whereas those of CK1ε and TIM were significantly up-regulated. Recovery of PER3 expression was observed in both patients with AML and those with ALL who achieved remission but not in patients who relapsed after treatment.
CONCLUSION: Circadian clock genes are altered in patients with acute leukemia and up-regulation of PER3 is correlated with a better clinical outcome.

Lu H, Chu Q, Xie G, et al.
Circadian gene expression predicts patient response to neoadjuvant chemoradiation therapy for rectal cancer.
Int J Clin Exp Pathol. 2015; 8(9):10985-94 [PubMed] Free Access to Full Article Related Publications
Preoperative neoadjuvant chemoradiation therapy may be useful in patients with operable rectal cancer, but treatment responses are variable. We examined whether expression levels of circadian clock genes could be used as biomarkers to predict treatment response. We retrospectively analyzed clinical data from 250 patients with rectal cancer, treated with neoadjuvant chemoradiation therapy in a single institute between 2011 and 2013. Gene expression analysis (RT-PCR) was performed in tissue samples from 20 patients showing pathological complete regression (pCR) and 20 showing non-pCR. The genes analyzed included six core clock genes (Clock, Per1, Per2, Cry1, Cry2 and Bmal1) and three downstream target genes (Wee1, Chk2 and c-Myc). Patient responses were analyzed through contrast-enhanced pelvic MRI and endorectal ultrasound, and verified by histological assessment. pCR was defined histologically as an absence of tumor cells. Among the 250 included patients, 70.8% showed regression of tumor size, and 18% showed pCR. Clock, Cry2 and Per2 expressions were significantly higher in the pCR group than in the non-pCR group (P<0.05), whereas Per1, Cry1 and Bmal1 expressions did not differ significantly between groups. Among the downstream genes involved in cell cycle regulation, c-Myc showed significantly higher expression in the pCR group (P<0.05), whereas Wee1 and Chk2 expression did not differ significantly between groups. Circadian genes are potential biomarkers for predicting whether a patient with rectal cancer would benefit from neoadjuvant chemoradiation therapy.

Morabito F, Cutrona G, Mosca L, et al.
Surrogate molecular markers for IGHV mutational status in chronic lymphocytic leukemia for predicting time to first treatment.
Leuk Res. 2015; 39(8):840-5 [PubMed] Related Publications
ZAP-70 is a marker of clinical outcome in chronic lymphocytic leukemia (CLL), however its assessment suffers from a lack of standardization consensus. To identify novel markers able to surrogate IGHV mutational status, CD19(+)CD5(+)-B-lymphocytes from 216 patients enrolled in a prospective study ( Identifier:NCT00917540), underwent gene expression profiling. Samples were split into CLL-Training (n=102) and CLL-Validation (n=114) sets, and an independent supervised analysis for IGHV mutational status was performed considering all genes with gene expression equal or above that of ZAP-70. Thirty-one genes (23 up- and 8 down-regulated) and 23 genes (18 up- and 5 down-regulated) satisfied these criteria in the CLL-Training and CLL-Validation sets, respectively, and 20 common genes (15 up and 5 down) were found to be differentially regulated in both sets. Two (SNORA70F, NRIP1) of the down-regulated and 6 (SEPT10, ZNF667, TGFBR3, MBOAT1, LPL, CRY1) of the up-regulated genes were significantly associated with a reduced risk of disease progression in both sets. Forcing the afore-mentioned genes in a Cox multivariate model together with IGHV mutational status, only CRY1 (HR=2.3, 95% CI: 1.1-4.9, P=.027) and MBOAT1 (HR=2.1, 95% CI: 1.1-3.7, P=.018) retained their independent prognostic impact, supporting the hypothesis that these genes may potentially act as surrogates for predicting IGHV mutational status.

Tavano F, Pazienza V, Fontana A, et al.
SIRT1 and circadian gene expression in pancreatic ductal adenocarcinoma: Effect of starvation.
Chronobiol Int. 2015; 32(4):497-512 [PubMed] Related Publications
Pancreatic cancer (PC), the fourth leading cause of cancer-related deaths, is characterized by high aggressiveness and resistance to chemotherapy. Pancreatic carcinogenesis is kept going by derangement of essential cell processes, such as proliferation, apoptosis, metabolism and autophagy, characterized by rhythmic variations with 24-h periodicity driven by the biological clock. We assessed the expression of the circadian genes ARNLT, ARNLT2, CLOCK, PER1, PER2, PER3, CRY1, CRY2 and the starvation-activated histone/protein deacetylase SIRT1 in 34 matched tumor and non-tumor tissue specimens of PC patients, and evaluated in PC derived cell lines if the modulation of SIRT1 expression through starvation could influence the temporal pattern of expression of the circadian genes. We found a significant down-regulation of ARNLT (p = 0.015), CRY1 (p = 0.013), CRY2 (p = 0.001), PER1 (p < 0.0001), PER2 (p < 0.001), PER3 (p = 0.001) and SIRT1 (p = 0.017) in PC specimens. PER3 and CRY2 expression levels were lower in patients with jaundice at diagnosis ( < 0.05). Having adjusted for age, adjuvant therapy and tumor stage, we evidenced that patients with higher PER2 and lower SIRT1 expression levels showed lower mortality (p = 0.028). Levels and temporal patterns of expression of many circadian genes and SIRT1 significantly changed upon serum starvation in vitro, with differences among four different PC cell lines examined (BXPC3, CFPAC, MIA-PaCa-2 and PANC-1). Serum deprivation induced changes of the overall mean level of the wave and amplitude, lengthened or shortened the cycle time and phase-advanced or phase-delayed the rhythmic oscillation depending on the gene and the PC cell line examined. In conclusion, a severe deregulation of expression of SIRT1 and circadian genes was evidenced in the cancer specimens of PC patients, and starvation influenced gene expression in PC cell lines, suggesting that the altered interplay between SIRT1 and the core circadian proteins could represent a crucial player in the process of pancreatic carcinogenesis.

Yu C, Yang SL, Fang X, et al.
Hypoxia disrupts the expression levels of circadian rhythm genes in hepatocellular carcinoma.
Mol Med Rep. 2015; 11(5):4002-8 [PubMed] Related Publications
Disturbance in the expression of circadian rhythm genes is a common feature in certain types of cancer, however the mechanisms mediating this disturbance remain to be elucidated. The present study aimed to investigate the effect of hypoxia on the expression of circadian rhythm genes in liver cancer cells and to identify the mechanisms underlying this effect in hepatocellular carcinoma (HCC). The HCC cell line, PLC/PRF/5. was treated with either a vehicle control or CoCl2 at 50, 100 or 200 µΜ for 24 h. Following treatment, the protein expression levels of hypoxia‑inducible factor (HIF)‑1α and HIF‑2α were detected by western blotting and the mRNA expression levels of circadian rhythm genes, including circadian locomotor output cycles kaput (Clock), brain and muscle Arnt‑like 1 (Bmal1), period (Per)1, Per2, Per3, cryptochrome (Cry)1, Cry2 and casein kinase Iε (CKIε), were detected by reverse transcription quantitative polymerase chain reaction (RT‑qPCR). Expression plasmids containing HIF‑1α or HIF‑2α were transfected into the PLC/PRF/5 cells using liposomes and RT‑qPCR was used to determine the effects of the transfections on the expression levels of circadian rhythm genes. Following treatment with CoCl2, the protein expression levels of HIF‑1α and HIF‑2α were upregulated in a CoCl2 concentration‑dependent manner. The mRNA expression levels of Clock, Bmal1 and Cry2 were increased, and the mRNA expression levels of Per1, Per2, Per3, Cry1 and CKIε were decreased following CoCl2 treatment (P<0.05). In the PLC/PRF/5 cells transfected with the plasmid containing HIF‑1α, the mRNA expression levels of Clock, Bmal1 and Cry2 were increased, and the mRNA expression levels of Per1, Per2, Per3, Cry1 and CKIε were decreased. In the PLC/PRF/5 cells transfected with the plasmid containing HIF‑2α, the mRNA expression levels of Clock, Bmal1, Per1, Cry1, Cry2 and CKIε were upregulated, and the mRNA expression levels of Per2 and Per3 were downregulated (P<0.05). A hypoxic microenvironment may contribute to the disturbance in the expression of circadian genes in HCC. HIF‑1α and HIF‑2α are involved in this process and have redundant, but not identical effects.

Cadenas C, van de Sandt L, Edlund K, et al.
Loss of circadian clock gene expression is associated with tumor progression in breast cancer.
Cell Cycle. 2014; 13(20):3282-91 [PubMed] Free Access to Full Article Related Publications
Several studies suggest a link between circadian rhythm disturbances and tumorigenesis. However, the association between circadian clock genes and prognosis in breast cancer has not been systematically studied. Therefore, we examined the expression of 17 clock components in tumors from 766 node-negative breast cancer patients that were untreated in both neoadjuvant and adjuvant settings. In addition, their association with metastasis-free survival (MFS) and correlation to clinicopathological parameters were investigated. Aiming to estimate functionality of the clockwork, we studied clock gene expression relationships by correlation analysis. Higher expression of several clock genes (e.g., CLOCK, PER1, PER2, PER3, CRY2, NPAS2 and RORC) was found to be associated with longer MFS in univariate Cox regression analyses (HR<1 and FDR-adjusted P < 0.05). Stratification according to molecular subtype revealed prognostic relevance for PER1, PER3, CRY2 and NFIL3 in the ER+/HER2- subgroup, CLOCK and NPAS2 in the ER-/HER2- subtype, and ARNTL2 in HER2+ breast cancer. In the multivariate Cox model, only PER3 (HR = 0.66; P = 0.016) and RORC (HR = 0.42; P = 0.003) were found to be associated with survival outcome independent of established clinicopathological parameters. Pairwise correlations between functionally-related clock genes (e.g., PER2-PER3 and CRY2-PER3) were stronger in ER+, HER2- and low-grade carcinomas; whereas, weaker correlation coefficients were observed in ER- and HER2+ tumors, high-grade tumors and tumors that progressed to metastatic disease. In conclusion, loss of clock genes is associated with worse prognosis in breast cancer. Coordinated co-expression of clock genes, indicative of a functional circadian clock, is maintained in ER+, HER2-, low grade and non-metastasizing tumors but is compromised in more aggressive carcinomas.

Markt SC, Valdimarsdottir UA, Shui IM, et al.
Circadian clock genes and risk of fatal prostate cancer.
Cancer Causes Control. 2015; 26(1):25-33 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Circadian genes may be involved in regulating cancer-related pathways, including cell proliferation, DNA damage response, and apoptosis. We aimed to assess the role of genetic variation in core circadian rhythm genes with the risk of fatal prostate cancer and first morning void urinary 6-sulfatoxymelatonin levels.
METHODS: We used unconditional logistic regression to evaluate the association of 96 single-nucleotide polymorphisms (SNPs) across 12 circadian-related genes with fatal prostate cancer in the AGES-Reykjavik cohort (n = 24 cases), the Health Professionals Follow-Up Study (HPFS) (n = 40 cases), and the Physicians' Health Study (PHS) (n = 105 cases). We used linear regression to evaluate the association between SNPs and first morning void urinary 6-sulfatoxymelatonin levels in AGES-Reykjavik. We used a kernel machine test to evaluate whether multimarker SNP sets in the pathway (gene based) were associated with our outcomes.
RESULTS: None of the individual SNPs were consistently associated with fatal prostate cancer across the three cohorts. In each cohort, gene-based analyses showed that variation in the CRY1 gene was nominally associated with fatal prostate cancer (p values = 0.01, 0.01, and 0.05 for AGES-Reykjavik, HPFS, and PHS, respectively). In AGES-Reykjavik, SNPs in TIMELESS (four SNPs), NPAS2 (six SNPs), PER3 (two SNPs) and CSNK1E (one SNP) were nominally associated with 6-sulfatoxymelatonin levels.
CONCLUSION: We did not find a strong and consistent association between variation in core circadian clock genes and fatal prostate cancer risk, but observed nominally significant gene-based associations with fatal prostate cancer and 6-sulfatoxymelatonin levels.

Zhang Z, Ma F, Zhou F, et al.
Functional polymorphisms of circadian negative feedback regulation genes are associated with clinical outcome in hepatocellular carcinoma patients receiving radical resection.
Med Oncol. 2014; 31(12):179 [PubMed] Related Publications
Previous studies have demonstrated that circadian negative feedback loop genes play an important role in the development and progression of many cancers. However, the associations between single-nucleotide polymorphisms (SNPs) in these genes and the clinical outcomes of hepatocellular carcinoma (HCC) after surgical resection have not been studied so far. Thirteen functional SNPs in circadian genes were genotyped using the Sequenom iPLEX genotyping system in a cohort of 489 Chinese HCC patients who received radical resection. Multivariate Cox proportional hazards model and Kaplan-Meier curve were used for the prognosis analysis. Cumulative effect analysis and survival tree analysis were used for the multiple SNPs analysis. Four individual SNPs, including rs3027178 in PER1, rs228669 and rs2640908 in PER3 and rs3809236 in CRY1, were significantly associated with overall survival (OS) of HCC patients, and three SNPs, including rs3027178 in PER1, rs228729 in PER3 and rs3809236 in CRY1, were significantly associated with recurrence-free survival (RFS). Moreover, we observed a cumulative effect of significant SNPs on OS and RFS (P for trend < 0.001 for both). Survival tree analysis indicated that wild genotype of rs228729 in PER3 was the primary risk factor contributing to HCC patients' RFS. Our study suggests that the polymorphisms in circadian negative feedback loop genes may serve as independent prognostic biomarkers in predicting clinical outcomes for HCC patients who received radical resection. Further studies with different ethnicities are needed to validate our findings and generalize its clinical utility.

Okabe T, Kumagai M, Nakajima Y, et al.
The impact of HIF1α on the Per2 circadian rhythm in renal cancer cell lines.
PLoS One. 2014; 9(10):e109693 [PubMed] Free Access to Full Article Related Publications
In mammals, the circadian rhythm central generator consists of interactions among clock genes, including Per1/2/3, Cry1/2, Bmal1, and Clock. Circadian rhythm disruption may lead to increased risk of cancer in humans, and deregulation of clock genes has been implicated in many types of cancers. Among these genes, Per2 is reported to have tumor suppressor properties, but little is known about the correlation between Per2 and HIF, which is the main target of renal cell carcinoma (RCC) therapy. In this study, the rhythmic expression of the Per2 gene was not detectable in renal cancer cell lines, with the exception of Caki-2 cells. In Caki-2 cells, HIF1α increased the amplitude of Per2 oscillation by directly binding to the HIF-binding site located on the Per2 promoter. These results indicate that HIF1α may enhance the amplitude of the Per2 circadian rhythm.

Hu ML, Yeh KT, Lin PM, et al.
Deregulated expression of circadian clock genes in gastric cancer.
BMC Gastroenterol. 2014; 14:67 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Gastric cancer (GC), an aggressive malignant tumor of the alimentary tract, is a leading cause of cancer-related death. Circadian rhythm exhibits a 24-hour variation in physiological processes and behavior, such as hormone levels, metabolism, gene expression, sleep and wakefulness, and appetite. Disruption of circadian rhythm has been associated with various cancers, including chronic myeloid leukemia, head and neck squamous cell carcinoma, hepatocellular carcinoma, endometrial carcinoma, and breast cancer. However, the expression of circadian clock genes in GC remains unexplored.
METHODS: In this study, the expression profiles of eight circadian clock genes (PER1, PER2, PER3, CRY1, CRY2, CKIϵ, CLOCK, and BMAL1) of cancerous and noncancerous tissues from 29 GC patients were investigated using real-time quantitative reverse-transcriptase polymerase chain reaction and validated through immunohistochemical analysis.
RESULTS: We found that PER2 was significantly up-regulated in cancer tissues (p < 0.005). Up-regulated CRY1 expression was significantly correlated with more advanced stages (stage III and IV) (p < 0.05).
CONCLUSIONS: Our results suggest deregulated expressions of circadian clock genes exist in GC and circadian rhythm disturbance may be associated with the development of GC.

Zarogoulidis P, Darwiche K, Huang H, et al.
Time recall; future concept of chronomodulating chemotherapy for cancer.
Curr Pharm Biotechnol. 2013; 14(6):632-42 [PubMed] Related Publications
The human metabolism is regulated by our internal clock; the circadian rhythm (24h-25h). There are several factors included in the regulatory pathway such as; genes (PER1-3), (CRY1-2), TIM hormones (cortisol, catecholamines, melatonin and insulin) drugs, enzymes, sleep disorders and diseases. Each one contributes in a different degree and in order to enhance the therapeutic result; we should include these factors into clusters instead of targeting each factor one by one. Malignances deregulate gene-protein expression/production, enzyme production, and in addition they induce fatigue, insomnia, stress and sleep disorders. All these factors finally contribute in minimizing the efficiency of chemotherapy treatment and quality of life. In addition, the circadian rhythm disruption induces tumor genesis, stress, and downregulates the defense and repair mechanisms of the human body. In the current mini review the underlying mechanism of the circadian rhythm is provided, along with the influence of sleep disturbances in cancer patient therapy. A proposal is presented to divide circadian rhythm and sleep disturbances into two major clusters with different management, however; with a common target to improve treatment efficiency and quality of life. Finally, a chrono-chemotherapy administration model is proposed in order to have less chemotherapy side effects.

Madden MH, Anic GM, Thompson RC, et al.
Circadian pathway genes in relation to glioma risk and outcome.
Cancer Causes Control. 2014; 25(1):25-32 [PubMed] Free Access to Full Article Related Publications
PURPOSE: There is growing evidence that circadian disruption may alter risk and aggressiveness of cancer. We evaluated common genetic variants in the circadian gene pathway for associations with glioma risk and patient outcome in a US clinic-based case-control study.
METHODS: Subjects were genotyped for 17 candidate single nucleotide polymorphisms in ARNTL, CRY1, CRY2, CSNK1E, KLHL30, NPAS2, PER1, PER3, CLOCK, and MYRIP. Unconditional logistic regression was used to estimate age and gender-adjusted odds ratios (OR) and 95 % confidence intervals (CI) for glioma risk under three inheritance models (additive, dominant, and recessive). Proportional hazards regression was used to estimate hazard ratios for glioma-related death among 441 patients with high-grade tumors. Survival associations were validated using The Cancer Genome Atlas (TCGA) dataset.
RESULTS: A variant in PER1 (rs2289591) was significantly associated with overall glioma risk (per variant allele OR 0.80; 95 % CI 0.66-0.97; p trend = 0.027). The variant allele for CLOCK rs11133391 under a recessive model increased risk of oligodendroglioma (OR 2.41; 95 % CI 1.31-4.42; p = 0.005), though not other glioma subtypes (p for heterogeneity = 0.0033). The association remained significant after false discovery rate adjustment (p = 0.008). Differential associations by gender were observed for MYRIP rs6599077 and CSNK1E rs1534891 though differences were not significant after adjustment for multiple testing. No consistent mortality associations were identified. Several of the examined genes exhibited differential expression in glioblastoma multiforme versus normal brain in TCGA data (MYRIP, ARNTL, CRY1, KLHL30, PER1, CLOCK, and PER3), and expression of NPAS2 was significantly associated with a poor patient outcome in TCGA patients.
CONCLUSION: This exploratory analysis provides some evidence supporting a role for circadian genes in the onset of glioma and possibly the outcome of glioma.

Kelleher FC, Rao A, Maguire A
Circadian molecular clocks and cancer.
Cancer Lett. 2014; 342(1):9-18 [PubMed] Related Publications
Physiological processes such as the sleep-wake cycle, metabolism and hormone secretion are controlled by a circadian rhythm adapted to 24h day-night periodicity. This circadian synchronisation is in part controlled by ambient light decreasing melatonin secretion by the pineal gland and co-ordinated by the suprachiasmatic nucleus of the hypothalamus. Peripheral cell autonomous circadian clocks controlled by the suprachiasmatic nucleus, the master regulator, exist within every cell of the body and are comprised of at least twelve genes. These include the basic helix-loop-helix/PAS domain containing transcription factors; Clock, BMal1 and Npas2 which activate transcription of the periodic genes (Per1 and Per2) and cryptochrome genes (Cry1 and Cry2). Points of coupling exist between the cellular clock and the cell cycle. Cell cycle genes which are affected by the molecular circadian clock include c-Myc, Wee1, cyclin D and p21. Therefore the rhythm of the circadian clock and cancer are interlinked. Molecular examples exist including activation of Per2 leads to c-myc overexpression and an increased tumor incidence. Mice with mutations in Cryptochrome 1 and 2 are arrhythmic (lack a circadian rhythm) and arrhythmic mice have a faster rate of growth of implanted tumors. Epidemiological finding of relevance include 'The Nurses' Health Study' where it was established that women working rotational night shifts have an increased incidence of breast cancer. Compounds that affect circadian rhythm exist with attendant future therapeutic possibilities. These include casein kinase I inhibitors and a candidate small molecule KL001 that affects the degradation of cryptochrome. Theoretically the cell cycle and malignant disease may be targeted vicariously by selective alteration of the cellular molecular clock.

Grundy A, Schuetz JM, Lai AS, et al.
Shift work, circadian gene variants and risk of breast cancer.
Cancer Epidemiol. 2013; 37(5):606-12 [PubMed] Related Publications
Circadian (clock) genes have been linked with several functions relevant to cancer, and epidemiologic research has suggested relationships with breast cancer risk for variants in NPAS2, CLOCK, CRY2 and TIMELESS. Increased breast cancer risk has also been observed among shift workers, suggesting potential interactions in relationships of circadian genes with breast cancer. Relationships with breast cancer of 100 SNPs in 14 clock-related genes, as well as potential interactions with shift work history, were investigated in a case-control study (1042 cases, 1051 controls). Odds ratios in an additive genetic model for European-ancestry participants (645 cases, 806 controls) were calculated, using a two-step correction for multiple testing: within each gene through permutation testing (10,000 permutations), and correcting for the false discovery rate across genes. Interactions of genotypes with ethnicity and shift work (<2 years vs ≥2 years) were evaluated individually. Following permutation analysis, two SNPs (rs3816360 in ARNTL and rs11113179 in CRY1) displayed significant associations with breast cancer and one SNP (rs3027188 in PER1) was marginally significant; however, none were significant following adjustment for the false discovery rate. No significant interaction with shift work history was detected. If shift work causes circadian disruption, this was not reflected in associations between clock gene variants and breast cancer risk in this study. Larger studies are needed to assess interactions with longer durations (>30 years) of shift work that have been associated with breast cancer.

Yu H, Meng X, Wu J, et al.
Cryptochrome 1 overexpression correlates with tumor progression and poor prognosis in patients with colorectal cancer.
PLoS One. 2013; 8(4):e61679 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Clock genes drive about 5-15% of genome-wide mRNA expression, and disruption of the circadian clock may deregulate the cell's normal biological functions. Cryptochrome 1 is a key regulator of the circadian feedback loop and plays an important role in organisms. The present study was conducted to investigate the expression of Cry1 and its prognostic significance in colorectal cancer (CRC). In addition, the function of Cry1 in human CRC was investigated in cell culture models.
METHODS: Real-time quantitative PCR, Western blot analysis and immunohistochemistry were used to explore Cry1 expression in CRC cell lines and primary CRC clinical specimens. MTT and colony formation assays were used to determine effects on cellular proliferation ability. The animal model was used to explore the Cry1 impact on the tumor cellular proliferation ability in vivo. Transwell assays were performed to detect the migration ability of the cell lines. Statistical analyzes were applied to evaluate the diagnostic value and the associations of Cry1 expression with clinical parameters.
RESULTS: Cry1 expression was up regulated in the majority of the CRC cell lines and 168 primary CRC clinical specimens at the protein level. Clinical pathological analysis showed that Cry1 expression was significantly correlated with lymph node metastasis (p = 0.004) and the TNM stage (p = 0.003). High Cry1 expression was associated with poor overall survival in CRC patients (p = 0.010). Experimentally, we found that up-regulation of Cry1 promoted the proliferation and migration of HCT116 cells, while down-regulation of Cry1 inhibited the colony formation and migration of SW480 cells.
CONCLUSIONS: These results suggest that Cry1 likely plays important roles in CRC development and progression andCry1 may be a prognostic biomarker and a promising therapeutic target for CRC.

Luo Y, Wang F, Chen LA, et al.
Deregulated expression of cry1 and cry2 in human gliomas.
Asian Pac J Cancer Prev. 2012; 13(11):5725-8 [PubMed] Related Publications
Growing evidence shows that deregulation of the circadian clock plays an important role in the development of malignant tumors, including gliomas. However, the molecular mechanisms of gene chnages controlling circadian rhythm in glioma cells have not been explored. Using real time polymerase chain reaction and immunohistochemistry techniques, we examined the expression of two important clock genes, cry1 and cry2, in 69 gliomas. In this study, out of 69 gliomas, 38 were cry1-positive, and 51 were cry2-positive. The expression levels of cry1 and cry2 in glioma cells were significantly different from the surrounding non-glioma cells (P<0.01). The difference in the expression rate of cry1 and cry 2 in high-grade (grade III and IV) and low-grade (grade 1 and II) gliomas was non-significant (P>0.05) but there was a difference in the intensity of immunoactivity for cry 2 between high-grade gliomas and low-grade gliomas (r=-0.384, P=0.021). In this study, we found that the expression of cry1 and cry2 in glioma cells was much lower than in the surrounding non-glioma cells. Therefore, we suggest that disturbances in cry1 and cry2 expression may result in the disruption of the control of normal circadian rhythm, thus benefiting the survival of glioma cells. Differential expression of circadian clock genes in glioma and non-glioma cells may provide a molecular basis for the chemotherapy of gliomas.

Hayashi A, Matsunaga N, Okazaki H, et al.
A disruption mechanism of the molecular clock in a MPTP mouse model of Parkinson's disease.
Neuromolecular Med. 2013; 15(2):238-51 [PubMed] Related Publications
Parkinson's disease (PD) is a common neurodegenerative disorder that is characterized by the degeneration of dopaminergic neurons in the substantia nigra and dopamine depletion in the striatum. Although the motor symptoms are still regarded as the main problem, non-motor symptoms in PD also markedly impair the quality of life. Several non-motor symptoms, such as sleep disturbances and depression, are suggested to be implicated in the alteration in circadian clock function. In this study, we investigated circadian disruption and the mechanism in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. MPTP-treated mice exhibited altered 24-h rhythms in body temperature and locomotor activity. In addition, MPTP treatment also affected the circadian clock system at the genetic level. The exposure of human neuroblastoma cells (SH-SY5Y) to 1-metyl-4-phenylpyridinium (MPP(+)) increased or decreased the mRNA levels of several clock genes in a dose-dependent manner. MPP(+)-induced changes in clock genes expression were reversed by Compound C, an inhibitor of AMP-activated protein kinase (AMPK). Most importantly, addition of ATP to the drinking water of MPTP-treated mice attenuated neurodegeneration in dopaminergic neurons, suppressed AMPK activation and prevented circadian disruption. The present findings suggest that the activation of AMPK caused circadian dysfunction, and ATP may be a novel therapeutic strategy based on the molecular clock in PD.

Relles D, Sendecki J, Chipitsyna G, et al.
Circadian gene expression and clinicopathologic correlates in pancreatic cancer.
J Gastrointest Surg. 2013; 17(3):443-50 [PubMed] Related Publications
INTRODUCTION: The circadian rhythm is responsible for physiologic homeostasis, behavior, and components of multiple metabolic processes. Disruption of the circadian rhythm is associated with cancer development, and several circadian clock genes have been implicated in loss of cell cycle control, impaired DNA damage repair, and subsequent tumor formation. Here, we investigated the expression profiles of several circadian clock genes in pancreatic ductal adenocarcinoma (PDA).
METHODS: Quantitative real-time polymerase chain reaction was used to examine the circadian clock genes (brain-muscle-like (Bmal)-ARNTL, circadian locomotor output cycles kaput (Clock), cryptochrome 1 (Cry1), cryptochrome 2 (Cry2), casein kinase 1ε (CK1ε), period 1 (Per1), period 2 (Per2), period 3 (Per3), timeless (Tim), and timeless-interacting protein (Tipin)) in PDA, as well as matching adjacent and benign tissue. Logistic regression models with robust variance were used to analyze the gene expression levels, and Kaplan-Meier survival curves were generated based on gene expression.
RESULTS: In the tumor tissue of PDA patients, compared to their matched adjacent tissue, expression levels of all circadian genes were lower, with statistical significance for Per1, Per2, Per3, Cry1, Cry2, Tipin, Tim, CK1ε, Bmal-ARNTL, and Clock (p < 0.025). PDA tumors also expressed significantly lower levels of the circadian genes when compared to benign lesions for Per1, Per2, Per3, Cry2, Tipin, and CK1ε. A significant association between low levels of expression in the tumors and reduced survival was found with Per1, Per2, Per3, Cry2, Tipin, CK1ε, Clock, and Bmal-ARNTL.
CONCLUSIONS: Our results reveal for the first time a dysregulated transcription of several circadian genes in PDA. Elevation of the gene levels in the benign and matched adjacent tissues may be indicative of their role during the process of tumorigenesis. The potential of using circadian genes as predictive markers of the outcomes and survival and distinguishing PDA from benign pancreas must be studied in larger populations to validate and demonstrate their eventual clinical utility.

Lengyel Z, Lovig C, Kommedal S, et al.
Altered expression patterns of clock gene mRNAs and clock proteins in human skin tumors.
Tumour Biol. 2013; 34(2):811-9 [PubMed] Related Publications
The majority of our genes may be regulated in a daily rhythm, including the genes for cell cycle control. Epidemiological and genetic evidences suggest that disruption of circadian timing mechanisms makes our cells more vulnerable to cancer formation. The aim of this study was to investigate the relationship between expression patterns of circadian clock genes (period homolog (per)1, per2, clock, and cry1) and tumor development by analyzing human skin biopsies of malignant melanoma and nonmalignant naevus tumors. We found that mRNA levels and nuclear immunopositivity for the investigated clock genes were reduced by 30-60 % in both melanoma and in naevus biopsies if compared with adjacent nontumorous samples. The alterations in melanoma presented significant associations with clinicopathological characteristics (e.g., Breslow thickness). Contrary to previous reports, the moderate decrease of per1 expression seen in malignant tissues could not be linked to malignant transformation itself; rather, it reflects only the alterations in tissue composition. In turn, clock expression was upregulated in nontumorous cells of melanoma biopsies but not in melanoma cells or naevus cells. As this gene (clock) is closely related to cellular metabolism, our data suggest its role in the impaired regulation of metabolism in malignant tumors. Our results present the first clinical evidence for a possible link between circadian clock genes and human skin tumorigenesis.

Doi M
Circadian clock-deficient mice as a tool for exploring disease etiology.
Biol Pharm Bull. 2012; 35(9):1385-91 [PubMed] Related Publications
One of the most significant conceptual changes brought about by the analysis of circadian clock-deficient mice is that abnormalities in the circadian clock are linked not only to sleep arousal disorder but also to a wide variety of common diseases, including hypertension, diabetes, obesity, and cancer. It has recently been shown that the disruption of the two cryptochrome genes Cry1 and Cry2-core elements of the circadian clock-induces salt-dependent hypertension due to abnormally high synthesis of the mineralocorticoid aldosterone by the adrenal gland. This adrenal disorder occurs as a result of increased expression of Hsd3b6, a newly identified steroidogenic enzyme that regulates aldosterone production within the adrenal zona glomerular cells. Importantly, this enzyme is functionally conserved in humans, and the pathophysiologic condition of human idiopathic hyperaldosteronism resembles that of Cry1/2-deficient mice. This review highlights the potential utility of circadian clock-deficient mice as a tool for exploring hitherto unknown disease etiology linked to the circadian clock.

Zhao B, Lu J, Yin J, et al.
A functional polymorphism in PER3 gene is associated with prognosis in hepatocellular carcinoma.
Liver Int. 2012; 32(9):1451-9 [PubMed] Related Publications
BACKGROUND: Previous studies have revealed that circadian genes play important roles in cell proliferation, apoptosis, cell cycle control, DNA damage response and treatment response of chemotherapy agents in cancers.
AIMS: We hypothesized that the polymorphisms in circadian genes may be associated with prognosis of hepatocellular carcinoma (HCC) patients treated with transcatheter arterial chemoembolization (TACE).
METHODS: Twelve functional single nucleotide polymorphisms (SNPs) in circadian negative feedback regulation genes (including CRY1, CRY2, PER1, PER2 and PER3) were genotyped using Sequenom iPLEX genotyping method in 337 HCC patients treated with TACE and analysed for associations with overall survival.
RESULTS: Our data showed that one SNP rs2640908 in PER3 gene was significantly associated with overall survival of HCC patients (P = 0.027). Patients carrying at least one variant allele of rs2640908 (WV + VV) had a significantly decreased risk of death (hazard ratio, 0.71; 95% confidence interval, 0.53-0.90), when compared with those carrying homozygous wild-type alleles (WW). Kaplan-Meier analyses showed a significantly longer median survival time in patients with WV + VV genotypes of SNP rs2640908 than those with WW genotype (11.6 months vs. 8.1 months; log rank P = 0.030). In addition, we also observed a significant difference on the genotype distribution of SNP rs2640908 in patients with and without portal vein thrombus (P = 0.041).
CONCLUSIONS: Our study provides the first evidence that a single functional polymorphism of PER3 gene is significantly associated with overall survival in HCC patients treated with TACE.

Hanoun M, Eisele L, Suzuki M, et al.
Epigenetic silencing of the circadian clock gene CRY1 is associated with an indolent clinical course in chronic lymphocytic leukemia.
PLoS One. 2012; 7(3):e34347 [PubMed] Free Access to Full Article Related Publications
Disruption of circadian rhythm is believed to play a critical role in cancer development. Cryptochrome 1 (CRY1) is a core component of the mammalian circadian clock and we have previously shown its deregulated expression in a subgroup of patients with chronic lymphocytic leukemia (CLL). Using real-time RT-PCR in a cohort of 76 CLL patients and 35 normal blood donors we now demonstrate that differential CRY1 mRNA expression in high-risk (HR) CD38+/immunoglobulin variable heavy chain gene (IgVH) unmutated patients as compared to low-risk (LR) CD38-/IgVH mutated patients can be attributed to down-modulation of CRY1 in LR CLL cases. Analysis of the DNA methylation profile of the CRY1 promoter in a subgroup of 57 patients revealed that CRY1 expression in LR CLL cells is silenced by aberrant promoter CpG island hypermethylation. The methylation pattern of the CRY1 promoter proved to have high prognostic impact in CLL where aberrant promoter methylation predicted a favourable outcome. CRY1 mRNA transcript levels did not change over time in the majority of patients where sequential samples were available for analysis. We also compared the CRY1 expression in CLL with other lymphoid malignancies and observed epigenetic silencing of CRY1 in a patient with B cell acute lymphoblastic leukemia (B-ALL).

Mazzoccoli G, Piepoli A, Carella M, et al.
Altered expression of the clock gene machinery in kidney cancer patients.
Biomed Pharmacother. 2012; 66(3):175-9 [PubMed] Related Publications
BACKGROUND AND AIM: Kidney cancer is associated with alteration in the pathways regulated by von Hippel-Lindau protein and hypoxia inducible factor α. Tight interrelationships have been evidenced between hypoxia response pathways and circadian pathways. The dysregulation of the circadian clock circuitry is involved in carcinogenesis. The aim of our study was to evaluate the clock gene machinery in kidney cancer.
METHODS: mRNA expression levels of the clock genes ARNTL1, ARNTL2, CLOCK, PER1, PER2, PER3, CRY1, CRY2, TIMELESS, TIPIN and CSNK1E and of the clock controlled gene SERPINE1 were evaluated by DNA microarray assays and by qRT-PCR in primary tumor and matched nontumorous tissue collected from a cohort of 11 consecutive kidney cancer patients.
RESULTS: In kidney tumor tissue, we found down-regulation of PER2 (median=0.658, Q1-Q3=0.562-0.744, P<0.01), TIMELESS (median=0.705, Q1-Q3=0.299-1.330, P=0.04) and TIPIN (median=0.556, Q1-Q3=0.385-1.945, P=0.01), up-regulation of SERPINE1 (median=1.628, Q1-Q3=0.339-4.071, P=0.04), whereas the expression of ARNTL2 (median=0.605, Q1-Q3=0.318-1.738, P=0.74) and CSNK1E (median=0.927, Q1-Q3=0.612-2.321, P=0.33) did not differ. A statistically significant correlation was evidenced between mRNA levels of PER2 and CSNKIE (r=0.791, P<0.01), PER2 and TIPIN (r=0.729, P=0.01), PER2 and SERPINE1 (r=0.704, P=0.01), TIMELESS and TIPIN (r=0.605, P=0.04), TIMELESS and CSNKIE (r=0.637, P=0.03), TIPIN and CSNKIE (r=0.940, P<0.01).
CONCLUSION: In kidney cancer, the circadian clock circuitry is deregulated and the altered expression of the clock genes might be involved in disease onset and progression.

Nemeth C, Humpeler S, Kallay E, et al.
Decreased expression of the melatonin receptor 1 in human colorectal adenocarcinomas.
J Biol Regul Homeost Agents. 2011 Oct-Dec; 25(4):531-42 [PubMed] Related Publications
Melatonin exerts anti-proliferative and pro-apoptotic effects in various cancer cell lines. Furthermore, there is evidence for impaired melatonin secretion in human breast and colorectal cancer. Additionally, several studies revealed a modulated expression of the melatonin receptor 1 (MT1), in human breast cancer specimens. Since melatonin binding sites were already identified in the human intestine, our aim is to identify the expression and to characterize the localization of the MT1 receptor in the human colon and in particular to compare MT1 expression levels between non-malignant and malignant colonic tissue. We assessed MT1 transcript levels with real time RT-PCR in colon adenocarcinomas and the adjacent normal colonic mucosa of 39 patients and observed a significant decrease of MT1 mRNA expression in colorectal cancer compared with the healthy adjacent mucosa tissue (0.67 mean difference, P < 0.0001). The results were confirmed at the protein level by Western blot analysis and by immunohistochemistry. MT1 was localized mainly supranuclear in colonic epithelial cells lining the crypts. We also evaluated mRNA expression of different clock genes in the colon samples and found a significant correlation between MT1 and Cryptochrome 1 (Cry1) expression (P < 0.01 for normal and P < 0.05 for tumour tissue). In conclusion, the decreased expression of MT1 in human colorectal cancer could point to a role of melatonin in this disease.

Pazienza V, Piepoli A, Panza A, et al.
SIRT1 and the clock gene machinery in colorectal cancer.
Cancer Invest. 2012; 30(2):98-105 [PubMed] Related Publications
SIRT1 and the clock genes are involved in carcinogenesis. We evaluated SIRT1 expression in 19 human colorectal cancer (CRC) specimens and clock gene expression in SIRT1-overexpressing CaCo2 and SW480 cells. In CRC, SIRT1 mean expression level was decreased. Compared to CaCo2 cells, SW480 cells displayed lower levels of SIRT1 and PER3 and higher levels of ARNTL1, CLOCK, PER1, PER2, CRY1, TIPIN, and CSNKIE. SIRT1 overexpression induced PER1 upregulation in CaCo2 and downregulation in SW480 cells. SIRT1 expression was heterogeneous in human CRC and in CRC cell lines. These results might have relevant implications for a better understanding of colorectal carcinogenesis.

Hsu CM, Lin SF, Lu CT, et al.
Altered expression of circadian clock genes in head and neck squamous cell carcinoma.
Tumour Biol. 2012; 33(1):149-55 [PubMed] Related Publications
Head and neck squamous cell carcinoma (HNSCC) means a group of cancers developed from the upper aerodigestive tract, and 90% of them are squamous cell carcinomas. HNSCC is the tenth most commonly diagnosed form of cancer in males worldwide, but it is the seventh most common cause of cancer-related death. The circadian clock regulates daily rhythmic variations in various physiologic processes including sleep and activity, appetite, hormone levels, metabolism, and gene expression. Many recent studies have demonstrated that the disruption of circadian rhythm is associated with cancer development and tumor progression, such as chronic myeloid leukemia, hepatocellular carcinoma, endometrial carcinoma, and breast cancer. However the direct links between aberrant circadian clock gene expression and human malignancies, including HNSCC, remain largely unknown. In this study, the expression profiles of nine circadian clock genes of cancer tissue and noncancerous part from 40 patients of HNSCC were investigated. The expression of PER1, PER2, PER3, CRY1, CRY2, CKIε, and BMAL1 showed significant downregulation in the cancer tissues (p < 0.005). Downregulated PER3, CRY2, and BMAL1 expression was correlated with more advanced cancer stages (p < 0.05). Downregulated PER3 and upregulated TIM expression correlated with larger tumor size (p < 0.05), and lower expression of PER3 correlated with deeper tumor invasion (p < 0.05). Poor survival was related to lower expression of PER1 (p < 0.05) and PER3 (p < 0.01). These results indicate a possible association of circadian clock gene, especially PER3, expression with the pathogenesis of HNSCC.

Mazzoccoli G, Panza A, Valvano MR, et al.
Clock gene expression levels and relationship with clinical and pathological features in colorectal cancer patients.
Chronobiol Int. 2011; 28(10):841-51 [PubMed] Related Publications
The clock gene machinery controls cellular metabolism, proliferation, and key functions, such as DNA damage recognition and repair. Dysfunction of the circadian clock is involved in tumorigenesis, and altered expression of some clock genes has been found in cancer patients. The aim of this study was to evaluate the expression levels of core clock genes in colorectal cancer (CRC). Quantitative real-time polymerase chain reaction (qPCR) was used to examine ARNTL1, CLOCK, PER1, PER2, PER3, CRY1, CRY2, Timeless (TIM), TIPIN, and CSNK1? expression levels in the tumor tissue and matched apparently healthy mucosa of CRC patients. In the tumor tissue of CRC patients, compared to their matched healthy mucosa, expression levels of ARNTL1 (p=.002), PER1 (p=.002), PER2 (p=.011), PER3 (p=.003), and CRY2 (p=.012) were lower, whereas the expression level of TIM (p=.044) was higher. No significant difference was observed in the expression levels of CLOCK (p=.778), CRY1 (p=.600), CSNK1 (p=.903), and TIPIN (p=.136). As to the clinical and pathological features, a significant association was found between low CRY1 expression levels in tumor mucosa and age (p=.026), and female sex (p=.005), whereas high CRY1 expression levels in tumor mucosa were associated with cancer location in the distal colon (p?=?.015). Moreover, high TIM mRNA levels in the tumor mucosa were prevalent whenever proximal lymph nodes were involved (p= .013) and associated with TNM stages III-IV (p=.005) and microsatellite instability (p=.015). Significantly poorer survival rates were evidenced for CRC patients with lower expression in the tumor tissue of PER1 (p=.010), PER3 (p= .010), and CSNKIE (p=.024). In conclusion, abnormal expression levels of core clock genes in CRC tissue may be related to the process of tumorigenesis and exert an influence on host/tumor interactions.

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