Role Of Clock Genes Research Articles

Chronopharmacology in cancer treatment: Optimizing drug timing for improved efficacy and reduced toxicity

Cancer treatment has seen remarkable advancements in recent years, but the accompanying side effects often diminish the patient's quality of life. To address this, the field of chronopharmacology has emerged, aiming to optimize cancer treatment by aligning it with the patient's circadian rhythms. This article explores the intricate relationship between the circadian clock and cancer susceptibility, the role of clock genes in tumor suppression, and the potential benefits of chronopharmacological approaches in chemotherapy and targeted therapies. Moreover, it discusses how chronobiological insights can be applied to palliative care and hormonal therapies, and how a patient-centered approach can tailor treatments to individual circadian rhythms. The regulatory and ethical considerations surrounding chronopharmacology are also examined. Ultimately, chronopharmacology offers the promise of more personalized and effective cancer treatments, enhancing patient well-being and outcomes in the battle against cancer.

CRH-R2 signalling modulates feeding and circadian gene expression in hypothalamic mHypoA-2/30 neurons.

The hypothalamic type 2 corticotropin releasing hormone receptor (CRH-R2) plays critical roles in homeostatic regulation, particularly in fine tuning stress recovery. During acute stress, the CRH-R2 ligands CRH and urocortins promote adaptive responses and feeding inhibition. However, in rodent models of chronic stress, over-exposure of hypothalamic CRH-R2 to its cognate agonists is associated with urocortin 2 (Ucn2) resistance; attenuated cAMP-response element binding protein (CREB) phosphorylation and increased food intake. The molecular mechanisms involved in these altered CRH-R2 signalling responses are not well described. In the present study, we used the adult mouse hypothalamus-derived cell line mHypoA-2/30 to investigate CRH-R2 signalling characteristics focusing on gene expression of molecules involved in feeding and circadian regulation given the role of clock genes in metabolic control. We identified functional CRH-R2 receptors expressed in mHypoA-2/30 cells that differentially regulate CREB and AMP-activated protein kinase (AMPK) phosphorylation and downstream expression of the appetite-regulatory genes proopiomelanocortin (Pomc) and neuropeptide Y (Npy) in accordance with an anorexigenic effect. We studied for the first time the effects of Ucn2 on clock genes in native and in a circadian bioluminescence reporter expressing mHypoA-2/30 cells, detecting enhancing effects of Ucn2 on mRNA levels and rhythm amplitude of the circadian regulator Aryl hydrocarbon receptor nuclear translocator-like protein 1 (Bmal1), which could facilitate anorexic responses in the activity circadian phase. These data uncover novel aspects of CRH-R2 hypothalamic signalling that might be important in regulation of circadian feeding during stress responses.

The Role of Clock Genes in Maintaining Circadian Rhythm and Rheumatoid Arthritis Pathophysiology.

Rheumatoid arthritis (RA) is a chronic, progressive autoimmune condition that affects up to 1% of the world population and symmetrically affects the joints leading to joint stiffness and decreased mobility. RA patients present with increased pain and chronic inflammation within their joint spaces, which researchers have linked to poorer sleep patterns, including difficulty falling asleep and non-restorative sleep. As such, identifying mediators of poor sleep quality among RA patients may improve their long-term quality of life. More recently, researchers identified an association between chronic inflammation in RA patients and their circadian rhythm. Altered circadian rhythms negatively impact the hypothalamic-pituitary-adrenal (HPA) axis and lead to altered cortisol release. Cortisol has shown to have a strong anti-inflammatory effect; when dysregulated, it may lead to increased pain experienced in RA patients. This literature review aims to provide insight into how chronic inflammation tied to RA pathophysiology may affect clock genes that are involved in maintaining the circadian rhythm. Specifically, this review focused on four common clock genes found dysregulated in RA patients: circadian locomotor output cycles kaput(CLOCK),brain and muscle ARNT like-1(BMAL1),period(PER),and cryptochrome(CRY).Of the four clock genes discussed in this review,BMAL1andPERare the most well-studied of the affected genes. Further knowledge surrounding clock genes and their dysregulated expression in RA may help guide therapy decisions for RA patients. Traditionally, disease-modifying antirheumatic drugs (DMARDs) have been used as first-line therapy for RA patients. Meanwhile, chronotherapy, optimizing drug release in a timed manner, has shown positive results in RA patients as well. Because of the association of altered circadian rhythms with increased symptom severity in RA patients, it seems highly plausible that DMARD therapy with chronotherapy may be an ideal therapeutic regimen for RA.

Role of Clock Genes and Circadian Rhythm in Renal Cell Carcinoma: Recent Evidence and Therapeutic Consequences.

Circadian rhythm regulates cellular differentiation and physiology and shapes the immune response. Altered expression of clock genes might lead to the onset of common malignant cancers, including Renal Cell Carcinoma (RCC). Data from Cancer Genome Atlas (TCGA) indicate that clock genes PER1-3, CRY2, CLOCK, NR1D2 and RORα are overexpressed in RCC tissues and correlate with patients' prognosis. The expression of clock genes could finely tune transcription factor activity in RCC and is associated with the extent of immune cell infiltration. The clock system interacts with hypoxia-induced factor-1α (HIF-1α) and regulates the circadian oscillation of mammalian target of rapamycin (mTOR) activity thereby conditioning the antitumor effect of mTOR inhibitors. The stimulation of natural killer (NK) cell activity exerted by the administration of interferon-α, a cornerstone of the first era of immunotherapy for RCC, relevantly varies according to circadian dosing time. Recent evidence demonstrated that time-of-day infusion directly affects the efficacy of immune checkpoint inhibitors in cancer patients. Compounds targeting the circadian clock have been identified and their role in the era of immunotherapy deserves to be further investigated. In this review, we aimed at addressing the impact of clock genes on the natural history of kidney cancer and their potential therapeutic implications.

Role of Omega-3 Fatty Acids as Non-Photic Zeitgebers and Circadian Clock Synchronizers.

Omega-3 fatty acids (ω-3 FAs) are well-known for their actions on immune/inflammatory and neurological pathways, functions that are also under circadian clock regulation. The daily photoperiod represents the primary circadian synchronizer (‘zeitgeber’), although diverse studies have pointed towards an influence of dietary FAs on the biological clock. A comprehensive literature review was conducted following predefined selection criteria with the aim of updating the evidence on the molecular mechanisms behind circadian rhythm regulation by ω-3 FAs. We collected preclinical and clinical studies, systematic reviews, and metanalyses focused on the effect of ω-3 FAs on circadian rhythms. Twenty animal (conducted on rodents and piglets) and human trials and one observational study providing evidence on the regulation of neurological, inflammatory/immune, metabolic, reproductive, cardiovascular, and biochemical processes by ω-3 FAs via clock genes were discussed. The evidence suggests that ω-3 FAs may serve as non-photic zeitgebers and prove therapeutically beneficial for circadian disruption-related pathologies. Future work should focus on the role of clock genes as a target for the therapeutic use of ω-3 FAs in inflammatory and neurological disorders, as well as on the bidirectional association between the molecular clock and ω-3 FAs.

Circadian Rhythm Dysregulation and Leukemia Development: The Role of Clock Genes as Promising Biomarkers.

The circadian clock (CC) is a daily system that regulates the oscillations of physiological processes and can respond to the external environment in order to maintain internal homeostasis. For the functioning of the CC, the clock genes (CG) act in different metabolic pathways through the clock-controlled genes (CCG), providing cellular regulation. The CC’s interruption can result in the development of different diseases, such as neurodegenerative and metabolic disorders, as well as cancer. Leukemias correspond to a group of malignancies of the blood and bone marrow that occur when alterations in normal cellular regulatory processes cause the uncontrolled proliferation of hematopoietic stem cells. This review aimed to associate a deregulated CC with the manifestation of leukemia, looking for possible pathways involving CG and their possible role as leukemic biomarkers.

The Potential Roles of Dec1 and Dec2 in Periodontal Inflammation.

Periodontal inflammation is a common inflammatory disease associated with chronic inflammation that can ultimately lead to alveolar attachment loss and bone destruction. Understanding autophagy and pyroptosis has suggested their significant roles in inflammation. In recent years, studies of differentiated embryo-chondrocyte expressed genes 1 and 2 (Dec1 and Dec2) have shown that they play important functions in autophagy and in pyroptosis, which contribute to the onset of periodontal inflammation. In this review, we summarize recent studies on the roles of clock genes, including Dec1 and Dec2, that are related to periodontal inflammation and other diseases.

Cell Autonomous Circadian Systems and Their Relation to Inflammation.

All living beings on earth have an important mechanism of 24-h periodicity, which controls their physiology, metabolism, and behavior. In humans, 24-h periodicity is regulated by the superchiasmatic nucleus (SCN) through external and environmental cues. Peripheral organs demonstrate circadian rhythms and circadian clock functions, and these are also observed in cultured cell lines. Every cell contains a CLOCK: BMAL1 loop for the generation of circadian rhythms. In this review, we focused on cell autonomous circadian rhythms in immune cells, the inflammatory diseases caused by disruption of circadian rhythms in hormones, and the role of clock genes in inflammatory diseases.

Depression-like behavior is associated with lower Per2 mRNA expression in the lateral habenula of rats.

Circadian rhythm dysfunction is primary symptom of depression and is closely related to depression onset. The role of the lateral habenula (LHb) of the thalamus in the pathogenesis of depression has been a research topic of great interest. The neuronal activity of this structure has circadian characteristics, which are related to the regulation of circadian rhythms. However, in depression model of rats, the role of clock genes in the LHb has not been assessed. To address this gap, we used a clomipramine (CLI) injection-induced depression model in rats to assess the daily expression of rhythmic genes in the LHb and depression-like behavior in rats at multiple time points. In determining the role of the Per2 gene in the development of depression-like behavior in the LHb, we found that the expression of this clock gene differed in a circadian manner. Per2 expression was also significantly decreased in CLI-treated rats in late afternoon (17:00) and in the middle of the night (1:00). Furthermore, silencing Per2 in the LHb of normal rats induced depression-like behavior at night, suggesting that Per2 may play an important role in the pathogenesis of depression. Collectively, these results indicate that decreased Per2 expression in the LHb may be related to increased depression-like behavior at night in depression model of rats.

Abstract MP141: Role of Cryptochrome in Angiogenesis

Background: Although clock genes generate oscillations in about 10 % of all gene expressions as a 24-hour cycle in the cellular level cooperating with the central clock, little is known about the role of clock genes in angiogenesis. Objective: The aim of this study was to determine if a peripheral clock would modulate angiogenesis in a hind limb ischemia (HLI) model. Methods and Results: First, we surgically induced the HLI model in C57BL/6J (wild type; WT) mice (N=6 for each time point) and checked mRNA expressions of clock genes in a local ischemic tissue by PCR array in the setting of blood perfusion recovery. In vitro study, we next investigated those gene expressions in human umbilical vein endothelial cells (HUVECs) with or without stimulation by growth factors. Those data demonstrated that the peripheral clock genes were modulated in ECs and tissues in the presence of growth factors and tissue ischemia. Then, we examined whether inhibition of clock gene expressions had any effects on angiogenesis. For this study, we focused on Cryptochrome (Cry), which is well known as one of the core-loop forming clock genes producing circadian rhythm in mammals. Our loss-of-function study revealed that the abilities of proliferation, migration and tube formation were significantly inhibited by Cry1 and Cry2 double knockdown in HUVECs. Interestingly, although the knockdown of Cry1 and Cry2 changed the mRNA expression of Period2, it did not affect those of BMAL1 and Clock in HUVECs. Finally, we tested if Cry1 and Cry2 double hetero knockout mice of HLI models displayed worse blood perfusion recoveries with deterioration of angiogenesis. As results, compared with control WT mice, Cry1 and Cry2 double knockout mice showed the low capillary density detected by CD31-immunohistochemistry and low tissue blood perfusion demonstrated by laser Doppler perfusion imaging (LDPI) in a HLI. Conclusion: Our data indicated that Cryptochrome as a peripheral clock plays an important role in angiogenesis of the reparative tissue ischemia model.

The Role of Clock Genes in Fibrinolysis Regulation: Circadian Disturbance and Its Effect on Fibrinolytic Activity.

The fibrinolytic system is critical during the onset of fibrinolysis, a fundamental mechanism for fibrin degradation. Both tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) trigger fibrinolysis, leading to proteolytic activation of plasminogen to plasmin and subsequently fibrin proteolysis. This system is regulated by several inhibitors; plasminogen activator inhibitor-1 (PAI-1), the most studied, binds to and inactivates both tPA and uPA. Through the action of plasmin, this system regulates several physiological processes: embryogenesis, activation of inflammatory cells, cell proliferation and death, synaptic plasticity, wound healing, and others. The deregulated intervention of fibrinolysis in the pathophysiology of various diseases has been widely studied; findings of altered functioning have been reported in different chronic non-communicable diseases (NCD), reinforcing its pleiotropic character and the importance of its physiology and regulation. The evidence indicates that fundamental elements of the fibrinolytic system, such as tPA and PAI-1, show a circadian rhythm in their plasmatic levels and their gene expression are regulated by circadian system elements, known as clock genes – Bmal, Clock, Cry-, and accessory clock genes such as Rev-Erb and Ror. The disturbance in the molecular machinery of the clock by exposure to light during the night alters the natural light/dark cycle and causes disruption of the circadian rhythm. Such exposure affects the synchronization and functioning of peripheral clocks responsible for the expression of the components of the fibrinolytic system. So, this circadian disturbance could be critical in the pathophysiology of chronic diseases where this system has been found to be deregulated.

P.490 The role of clock genes in perinatal depression: The light in the darkness

P.490 The role of clock genes in perinatal depression: The light in the darkness

A Novel Diabetic Mouse Model for Real-Time Monitoring of Clock Gene Oscillation and Blood Pressure Circadian Rhythm.

Diabetic patients have an increased prevalence of blood pressure (BP) circadian rhythm disruption, which is associated with an increased risk of target organ damage and detrimental cardiovascular events. Limited information is available regarding the role of clock genes in the disruption of BP circadian rhythm in diabetes due to the lack of a diabetic animal model that allows real-time monitoring of clock gene oscillation. Here, we generated a novel diabetic db/db-mPer2Luc mouse model by crossing type 2 diabetic db/db mice with mPer2Luc knock-in mice. The daily rhythms of BP, heart rate, locomotor activity, and food and water intake were acquired by radiotelemetry or using metabolic chambers. The daily oscillation of mPer2 bioluminescence was recorded by LumiCycle in real-time in tissue explants and using the IVIS system in vivo. Our results show that db/db-mPer2Luc mice are obese, diabetic, and glucose intolerant. The db/db-mPer2Luc mice displayed a compromised BP daily rhythm, which was associated with disrupted daily rhythms in baroreflex sensitivity, locomotor activity, and metabolism, but not heart rate or food and water intake. The phase of the mPer2 daily oscillation was advanced to different extents in the explanted peripheral tissues from db/db-mPer2Luc mice relative to control mice. In contrast, no phase shift was detected in mPer2 daily oscillations in the explanted SCN. Moreover, advanced phase shift of the mPer2 daily oscillation was detected in the liver, kidney and submandibular gland in vivo of db/db-mPer2Luc mice. In conclusion, the diabetic db/db-mPer2Luc mouse is a novel animal model that allows real-time monitoring of mPer2 circadian rhythms ex vivo and in vivo. The results from db/db-mPer2Luc mice suggest that the desynchrony of mPer2 daily oscillation in peripheral tissues contributes to the loss of BP daily oscillation in diabetes.

Abstract 1412: Comprehensive characterization of clock genes in human cancers

Abstract Cancer chronotherapy has been considered to optimize the balance of anti-tumor effects and toxicity. To develop cancer chronotherapy, the first crucial step is to understand the significant roles of clock genes in cancer. Circadian machinery is controlled by two main transcription auto-regulatory feedback loops, which including 14 core circadian genes. Core clock genes have at least one paralog gene may be functionally redundant in circadian regulation. Dysregulation of circadian genes promotes tumorigenesis through mechanisms that include the cell cycle, DNA damage and metabolism. However, there has been no comprehensive analysis to characterize the roles of circadian genes and circadian rhythms in tumorigenesis and to assess their potential utility in cancer chronotherapy. We determined genetic and epigenetic alterations of clock genes in human cancer, and explore clock gene clinical effect through integrative analysis, based on The Cancer Genome Atlas (TCGA) profiles contained DNA, RNA, protein, epigenetic levels and clinical data. Our results suggested several clock genes may function as oncogene, such as ARNTL2, NR1D1, and NPAS2, while several other clock genes may function as tumor suppressors, such as PERs, CRYs, RORs. We revealed disruption and reprogramming of circadian rhythms across patient samples by showing significantly reduced number of genes correlated to clock genes. We further showed that transcriptional dysregulation of clock genes is strongly associated with patient survival, tumor stage and subtype. Taken together, our results provide the comprehensive analysis of clock system across different cancer types and expected outcomes will lay the groundwork for the future development of cancer chronotherapy. Citation Format: Youqiong Ye, Yu Xiang, Joseph Takahashi, Gordon Mills, Seung-Hee Yoo, Leng Han. Comprehensive characterization of clock genes in human cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1412.

Food-Anticipatory Behavior in Neonatal Rabbits and Rodents: An Update on the Role of Clock Genes.

In mammals, the suprachiasmatic nucleus (SCN), the master circadian clock, is mainly synchronized to the environmental light/dark cycle. SCN oscillations are maintained by a molecular clockwork in which certain genes, Period 1–2, Cry1–2, Bmal1, and Clock, are rhythmically expressed. Disruption of these genes leads to a malfunctioning clockwork and behavioral and physiological rhythms are altered. In addition to synchronization of circadian rhythms by light, when subjects are exposed to food for a few hours daily, behavioral and physiological rhythms are entrained to anticipate mealtime, even in the absence of the SCN. The presence of anticipatory rhythms synchronized by food suggests the existence of an SCN-independent circadian pacemaker that might be dependent on clock genes. Interestingly, rabbit pups, unable to perceive light, suckle milk once a day, which entrains behavioral rhythms to anticipate nursing time. Mutations of clock genes, singly or in combination, affect diverse rhythms in brain activity and physiological processes, but anticipatory behavior and physiology to feeding time remains attenuated or unaffected. It had been suggested that compensatory upregulation of paralogs or subtypes genes, or even non-transcriptional mechanisms, are able to maintain circadian oscillations entrained to mealtime. In the present mini-review, we evaluate the current state of the role played by clock genes in meal anticipation and provide evidence for rabbit pups as a natural model of food-anticipatory circadian behavior.

Health risks associated with genetic alterations in internal clock system by external factors.

The circadian system maintains the main aspects of physiological and behavioral processes. Both circadian rhythm and sleep impact an organism's health through interaction with environmental factors. Variations in external factors influence the functionality of clock genes and disrupt 24-hour rhythmic cycle. The disrupted circadian rhythm and disregulated sleep affect an organism's health, thereby causing several disorders including cancer, depression and cardiac disorders. Considering the role of clock genes and environmental factors, extensive investigation is required focusing on pathways involved in development of life-threatening disorders. This review identifies the major risks and associated factors related with disruption in circadian system and sleep.

Circadian clock and oral cancer.

The circadian clock is comprised of a master component situated in the hypothalamic suprachiasmatic nucleus and subordinate clock genes in almost every cell of the body. The circadian clock genes and their encoded proteins govern the organism to follow the natural signals of time, and adapt to external changes in the environment. The majority of physiological processes in mammals exhibit variable circadian rhythms, which are generated and coordinated by an oscillation in the expression of the clock genes. A number of studies have reported that alteration in the expression level of clock genes is correlated with several pathological conditions, including cancer. However, little is known about the role of clock genes in homeostasis of the oral epithelium and their disturbances in oral carcinogenesis. The present review summarizes the current state of knowledge of the implications of clock genes in oral cancer. It has been demonstrated that the development of oral squamous cell carcinoma undergoes circadian oscillation in relation to tumor volume and proliferation rate. The circadian clock gene period (PER)1 has been associated with oral cancer pathogenesis and it is suggested that changes in the expression of PER1 may exhibit an important role in the development, invasion, and metastasis of oral squamous cell carcinoma. However, its role remains elusive and there is a need for further research in order to understand the underlying mechanisms of the clock genes in oral cancer pathogenesis.

Desynchronization of Circadian Clocks in Cancer: A Metabolic and Epigenetic Connection.

Circadian clocks are innate oscillators that drive daily rhythms in metabolism, physiology, and behavior. 24-h rhythms in gene expression, driven by core clock transcription factors, reflect the epigenetic state of the cell, which in turn is dictated by the metabolic environment. Cancer cells alter their metabolic state and gene expression and therefore are likely to tweak circadian clock function in their favor. Over the past decade, we have witnessed an extraordinary increase in systems-level studies that suggest intricate mechanistic links between the cellular metabolome and the circadian epigenome. In parallel, reprogramming of cellular clock function in cancers is increasingly evident and the role of clock genes in the development of hematological tumors, as well as their pathophysiological effects on tissues distal to the tumor, has been described. Furthermore, the interplay between components of the circadian clock, metabolic enzymes, and oncogenes is starting to be better understood, such as the close association between overexpression of the Myc oncogene and perturbation of circadian and metabolic rhythms, thus opening new avenues to treat cancers. This review article explores current knowledge on the circadian metabolome and the molecular pathways they control, with a focus on their involvement in the development of hematopoietic malignancies.

704. Circadian Clock Genes and Lithium Response in Bipolar Disorder

Circadian rhythm abnormalities are a central clinical feature of bipolar disorder (BD), affecting rhythms in sleep and activity. The mood stabilizer lithium corrects circadian rhythm abnormalities in bipolar disorder and changes the expression of “clock genes” that direct rhythms. However, the role of clock genes in bipolar disorder is unknown, and it is unclear if lithium’s effects on rhythms are relevant to treatment outcomes.

CLOCK promotes 3T3-L1 cell proliferation via Wnt signaling.

Circadian genes control most of the physiological functions including cell cycle. Cell proliferation is a critical factor in the differentiation of progenitor cells. However, the role of Clock gene in the regulation of cell cycle via wingless-type (Wnt) pathway and the relationship between Clock and adipogenesis are unclear. We found that the circadian locomotor output cycles kaput (Clock) regulated the proliferation and the adipogenesis of 3T3-L1 preadipocytes. We found that Clock attenuation inhibited the viability of 3T3-L1 preadipocytes in the cell counting kit 8. The expression of c-Myc and Cyclin D1 decreased dramatically in 3T3-L1 when Clock was silenced with short interfering RNA and was also decreased in fat tissue and adipose tissue-derived stem cells of Clock(Δ19) mice. Clock directly controls the expression of the components of Wnt signal transduction pathway, which was verified by serum shock, chromatin immunoprecipitation, Western blot, and quantitative real-time polymerase chain reaction (qRT-PCR). Furthermore, IWR-1, a Wnt signal pathway inhibitor, inhibited the cell cycle promotion by CLOCK, which was detected by cell viability assay, flow cytometry, and qRT-PCR. Therefore, CLOCK transcription control of Wnt signaling promotes cell cycle progression in 3T3-L1 preadipocytes. Clock inhibited the adipogenesis on day 2 in 3T3-L1 cells via Oil Red O staining and qRT-PCR detection and probably related to cellular differentiation. These data provide evidence that the circadian gene Clock regulates the proliferation of preadipocytes and affects adipogenesis. © 2016 IUBMB Life, 68(7):557-568, 2016.