Host circadian clock as a control point in tumor progression

Long-term survival, toxicities, and the role of chrono-chemotherapy with different infusion rates in locally advanced nasopharyngeal carcinoma patients treated with intensity-modulated radiation therapy: a retrospective study with a 5-year follow-up

Purpose

This study aimed to evaluate 5-year outcomes and the late toxicity profile of chrono-chemotherapy with different infusion rates in patients with locally advanced nasopharyngeal carcinoma (NPC).

Methods and materials

Our retrospective analysis included 70 patients with locally advanced NPC stages III and IVB (according to the 2010 American Joint Committee on Cancer staging system). Patients were treated with two cycles of induction chemotherapy (IC) before concurrent chemoradiotherapy (CCRT) at Guizhou Cancer Hospital. The IC with docetaxel, cisplatin (DDP) and fluorouracil regimen. Patients were divided into two groups during CCRT. Using a "MELODIE" multi-channel programmed pump, DDP (100 mg/m2) was administered for 12 hours from 10:00 am to 10:00 pm and repeated every 3 weeks for 2-3 cycles. DDP was administered at the peak period of 4:00 pm in the sinusoidal chrono-modulated infusion group (Arm A, n=35). The patients in Arm B received a constant rate of infusion. Both arms received radiotherapy through the same technique and dose fraction. The long-term survival and disease progression were observed.

Results

After a median follow-up of 82.8 months, the 5-year progression-free survival rate was 81.3% in Arm A and 79.6% in Arm B (P = 0.85). The 5-year overall survival rate was not significantly different between Arm A and Arm B (79.6% vs 85.3%, P = 0.79). The 5-year distant metastasis-free survival rate was 83.6% in Arm A and 84.6% in Arm B (P = 0.75). The 5-year local recurrence-free survival rate was 88.2% in Arm A and 85.3% in Arm B (P = 0.16). There were no late toxicities of grade 3-4 in either group. Both groups had grade 1-2 late toxicities. Dry mouth was the most common late toxic side effect, followed by hearing loss and difficulty in swallowing. There was no statistically significant difference between Arm A and Arm B in terms of side effects.

Conclusion

Long-term analysis confirmed that in CCRT, cisplatin administration with sinusoidal chrono-modulated infusion was not superior to the constant infusion rate in terms of long-term toxicity and prognosis.

Forces at play: exploring factors affecting the cancer metastasis

Metastatic disease, a leading and lethal indication of deaths associated with tumors, results from the dissemination of metastatic tumor cells from the site of primary origin to a distant organ. Dispersion of metastatic cells during the development of tumors at distant organs leads to failure to comply with conventional treatments, ultimately instigating abrupt tissue homeostasis and organ failure. Increasing evidence indicates that the tumor microenvironment (TME) is a crucial factor in cancer progression and the process of metastatic tumor development at secondary sites. TME comprises several factors contributing to the initiation and progression of the metastatic cascade. Among these, various cell types in TME, such as mesenchymal stem cells (MSCs), lymphatic endothelial cells (LECs), cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), T cells, and tumor-associated macrophages (TAMs), are significant players participating in cancer metastasis. Besides, various other factors, such as extracellular matrix (ECM), gut microbiota, circadian rhythm, and hypoxia, also shape the TME and impact the metastatic cascade. A thorough understanding of the functions of TME components in tumor progression and metastasis is necessary to discover new therapeutic strategies targeting the metastatic tumor cells and TME. Therefore, we reviewed these pivotal TME components and highlighted the background knowledge on how these cell types and disrupted components of TME influence the metastatic cascade and establish the premetastatic niche. This review will help researchers identify these altered components' molecular patterns and design an optimized, targeted therapy to treat solid tumors and restrict metastatic cascade.

Platform-independent estimation of human physiological time from single blood samples

Abundant epidemiological evidence links circadian rhythms to human health, from heart disease to neurodegeneration. Accurate determination of an individual's circadian phase is critical for precision diagnostics and personalized timing of therapeutic interventions. To date, however, we still lack an assay for physiological time that is accurate, minimally burdensome to the patient, and readily generalizable to new data. Here, we present TimeMachine, an algorithm to predict the human circadian phase using gene expression in peripheral blood mononuclear cells from a single blood draw. Once trained on data from a single study, we validated the trained predictor against four independent datasets with distinct experimental protocols and assay platforms, demonstrating that it can be applied generalizably. Importantly, TimeMachine predicted circadian time with a median absolute error ranging from 1.65 to 2.7 h, regardless of systematic differences in experimental protocol and assay platform, without renormalizing the data or retraining the predictor. This feature enables it to be flexibly applied to both new samples and existing data without limitations on the transcriptomic profiling technology (microarray, RNAseq). We benchmark TimeMachine against competing approaches and identify the algorithmic features that contribute to its performance.

Exercise training induces alteration of clock genes and myokines expression in tumor-bearing mice

To investigate the impact of different exercise training schedules (following a fixed schedule or at random times of the day) on clock genes and myokine expression patterns in the skeletal muscle of tumor-bearing mice. Mice were divided into three groups: tumor (LLC), tumor + exercise training (LLC + T) always performed at the same time of the day (ZT2) and exercise training at random times of the day (ZTAlt). Mice were inoculated subcutaneously with Lewis lung carcinoma cells. The gastrocnemius muscle was dissected and the clock gene expression (Clock/Per1/Per2/Per3/Rev-Erbα/GAPDH) was investigated by quantitative reverse transcription polymerase chain reaction with SYBR® Green. Myokine content in muscle (tumour necrosis factor alpha/IL-10/IL-4) was assessed by enzyme-linked immunosorbent assay. At the end of the protocol, the trained groups showed a reduction in total weight, when compared to Lewis lung carcinoma. Tumor weight was lower in the LLC + T (ZTAlt), when compared to LLC. Clock gene mRNA expression showed a significant increase for ZT20 in the groups that performed physical exercise at LLC + T (ZTAlt), when compared with LLC. The Per family showed increased mRNA expression in ZT4 in both trained mice groups, when compared with LLC. LLC + T (ZTAlt) presented reduction of the expression of anti-inflammatory myokines (Il-10/IL-4) during the night, compared with LLC + T(ZT2). Exercise training is able to induce marked modification of clock gene expression and of the production of myokines, in a way that is dependent on schedule exercise training strategy. Taken together, the results show that exercise is a potent Zeitgeber and may thus contribute to change clock genes expression and myokines that are able to reduce the tumor weight.

Circadian disruption does not alter tumorigenesis in a mouse model of lymphoma

Background: Disruption of natural light cycles, as experienced by shift workers, is linked to enhanced cancer incidence. Several mouse models of cancer develop more severe disease when exposed to irregular light/dark cycles, supporting the connection between circadian disruption and increased cancer risk. Cryptochrome 2 (CRY2), a repressive component of the molecular circadian clock, facilitates turnover of the oncoprotein c-MYC, one mechanism that may link the molecular clock to tumorigenesis. In Eμ-MYC mice, which express transgenic c-MYC in B cells and develop aggressive lymphomas and leukemia, global Cry2 deletion reduces survival and enhances tumor formation. Lighting conditions that mimic the disruption experienced by shift workers dampen Cry2 transcripts in peripheral tissues of C57BL/6J mice. Although it is milder than homozygous deletion of Cry2, we hypothesized that reduced Cry2 rhythmicity could alter MYC protein accumulation and contribute to enhanced cancer risk caused by circadian disruption. We tested this hypothesis in MYC-driven lymphoma. Methods: We housed Eμ-MYC mice in light-tight boxes set to either control (continuous cycles of 12-hours of light followed by 12-hours of dark, LD12:12) or chronic jetlag (eight-hour light phase advances every two to three days, CJL) lighting conditions and assessed the impact of disrupted light cycles on survival and tumor formation in Eμ-MYC mice. Results: Environmental disruption of circadian rhythms did not alter tumor location, tumor growth, or survival in Eμ-MYC mice. Conclusions: Dampened rhythms of Cry2 following disruption of circadian light exposures is milder than deletion of Cry2. The lack of phenotype caused by altered circadian gene expression in contrast to enhanced tumorigenesis caused by homozygous deletion of Cry2 suggests that CRY2 dosage impacts this model. Importantly, these findings indicate that increased cancer risk associated with circadian disruption arises from one or more mechanisms that are not recapitulated here, and may be different in distinct tumor types.

Disruption of the Clock Component Bmal1 in Mice Promotes Cancer Metastasis through the PAI-1-TGF-β-myoCAF-Dependent Mechanism

The circadian clock in animals and humans plays crucial roles in multiple physiological processes. Disruption of circadian homeostasis causes detrimental effects. Here, it is demonstrated that the disruption of the circadian rhythm by genetic deletion of mouse brain and muscle ARNT-like 1 (Bmal1) gene, coding for the key clock transcription factor, augments an exacerbated fibrotic phenotype in various tumors. Accretion of cancer-associated fibroblasts (CAFs), especially the alpha smooth muscle actin positive myoCAFs, accelerates tumor growth rates and metastatic potentials. Mechanistically, deletion of Bmal1 abrogates expression of its transcriptionally targeted plasminogen activator inhibitor-1 (PAI-1). Consequently, decreased levels of PAI-1 in the tumor microenvironment instigate plasmin activation through upregulation of tissue plasminogen activator and urokinase plasminogen activator. The activated plasmin converts latent TGF-β into its activated form, which potently induces tumor fibrosis and the transition of CAFs into myoCAFs, the latter promoting cancer metastasis. Pharmacological inhibition of the TGF-β signaling largely ablates the metastatic potentials of colorectal cancer, pancreatic ductal adenocarcinoma, and hepatocellular carcinoma. Together, these data provide novel mechanistic insights into disruption of the circadian clock in tumor growth and metastasis. It is reasonably speculated that normalization of the circadian rhythm in patients provides a novel paradigm for cancer therapy.

The circadian clock, aging and its implications in cancer

Circadian clock orchestrates the intergenic biochemical, physiological and behavioral changes to form an approximate 24h oscillation through the transcription-translation feedback loop (TTFL). Mechanistically, a heterodimer of transcriptional activator formed by BMAL1 and CLOCK, governs the expression of its transcriptional repressors, CRY, PER and REV-ERBα/β proteins, thereby controlling more than 50 % of protein encoding genes in human. There is also increasing evidence showing that tumor microenvironment can disrupt specific clock gene functions to facilitate tumorigenesis. Although there is great progress in understanding the molecular mechanisms of the circadian clock, aging and cancer, elucidating their complex relationships among these processes remains challenging. Herein, the optimization of the chronochemotherapy regimen has not been justified yet for treatment of cancer. Here, we discuss the hypothesis of relocalization of chromatin modifiers (RCM) along with function(s) of the circadian rhythm on aging and carcinogenesis. We will also introduce the function of the chromatin remodeling as a new avenue for rejuvenation of competent tissues to combat aging and cancer.

Effects of the Light/Dark Phase and Constant Light on Spatial Working Memory and Spine Plasticity in the Mouse Hippocampus

Circadian rhythms in behavior and physiology such as rest/activity and hormones are driven by an internal clock and persist in the absence of rhythmic environmental cues. However, the period and phase of the internal clock are entrained by the environmental light/dark cycle. Consequently, aberrant lighting conditions, which are increasing in modern society, have a strong impact on rhythmic body and brain functions. Mice were exposed to three different lighting conditions, 12 h light/12 h dark cycle (LD), constant darkness (DD), and constant light (LL), to study the effects of the light/dark cycle and aberrant lighting on the hippocampus, a critical structure for temporal and spatial memory formation and navigation. Locomotor activity and plasma corticosterone levels were analyzed as readouts for circadian rhythms. Spatial working memory via Y-maze, spine morphology of Golgi-Cox-stained hippocampi, and plasticity of excitatory synapses, measured by number and size of synaptopodin and GluR1-immunreactive clusters, were analyzed. Our results indicate that the light/dark cycle drives diurnal differences in synaptic plasticity in hippocampus. Moreover, spatial working memory, spine density, and size and number of synaptopodin and GluR1 clusters were reduced in LL, while corticosterone levels were increased. This indicates that acute constant light affects hippocampal function and synaptic plasticity.

Multicentre, interventional, single-arm study protocol of telemonitored circadian rhythms and patient-reported outcomes for improving mFOLFIRINOX safety in patients with pancreatic cancer (MultiDom, NCT04263948)

INTRODUCTION

Circadian clocks regulate cellular proliferation and drug effects. Tolerability and/or efficacy of anticancer therapies have been improved by their administration according to circadian rhythms, while being predicted by circadian robustness. The combination of leucovorin, fluorouracil, irinotecan and oxaliplatin (mFOLFIRINOX) is a standard treatment for pancreatic ductal adenocarcinoma (PDAC), that generates grades 3-4 adverse events in the majority of patients and an estimated 15%-30% emergency admission rate. The MultiDom study evaluates whether mFOLFIRINOX safety can be improved using a novel circadian-based telemonitoring-telecare platform in patients at home. The detection of early warning signals of clinical toxicities could guide their early management, possibly preventing emergency hospital admissions.

METHODS AND ANALYSIS

This multicentre, interventional, prospective, longitudinal, single-arm study hypothesises that the mFOLFIRINOX-related emergency admission rate will be 5% (95% CI 1.7% to 13.7%), among 67 patients with advanced PDAC. Study participation is 7 weeks for each patient, including a reference week before chemotherapy onset and 6 weeks afterwards. Accelerometry and body temperature are measured q1-min using a continuously worn telecommunicating chest surface sensor, daily body weight is self-measured with a telecommunicating balance and 23 electronic patient-reported outcomes (e-PROs) are self-rated using a tablet. Hidden Markov model, spectral analyses and other algorithms automatically compute physical activity, sleep, temperature, body weight change, e-PRO severity and 12 circadian sleep/activity parameters, including the dichotomy index I<O (% activity 'in-bed' below median activity 'out-of-bed'), once to four times daily. Health professionals access visual displays of near-real time parameter dynamics and receive automatic alerts, with trackable digital follow-up.

ETHICS AND DISSEMINATION

The study has been approved by the National Agency for Medication and Health Product Safety (ANSM) and Ethics Committee West V (2 July 2019; third amendment, 14 June 2022). The data will be disseminated at conferences and in peer-reviewed journals and will support large-scale randomised evaluation.

TRIAL REGISTRATION NUMBERS

NCT04263948 and ID RCB-2019-A00566-51.

"Time" for obesity-related cancer: The role of the circadian rhythm in cancer pathogenesis and treatment

The circadian rhythm is regulated by an intrinsic time-tracking system, composed both of a central and a peripheral clock, which influences the cycles of activities and sleep of an individual over 24 h. At the molecular level, the circadian rhythm begins when two basic helix-loop-helix/Per-ARNT-SIM (bHLH-PAS) proteins, BMAL-1 and CLOCK, interact with each other to produce BMAL-1/CLOCK heterodimers in the cytoplasm. The BMAL-1/CLOCK target genes encode for the repressor components of the clock, cryptochrome (Cry1 and Cry2) and the Period proteins (Per1, Per2 and Per3). It has been recently demonstrated that the disruption of circadian rhythm is associated with an increased risk of developing obesity and obesity-related diseases. In addition, it has been demonstrated that the disruption of the circadian rhythm plays a key role in tumorigenesis. Further, an association between the circadian rhythm disruptions and an increased incidence and progression of several types of cancer (e.g., breast, prostate, colorectal and thyroid cancer) has been found. As the perturbation of circadian rhythm has adverse metabolic consequences (e.g., obesity) and at the same time tumor promoter functions, this manuscript has the aim to report how the aberrant circadian rhythms affect the development and prognosis of different types of obesity-related cancers (breast, prostate, colon rectal and thyroid cancer) focusing on both human studies and on molecular aspects.

Using bioluminescence to image gene expression and spontaneous behavior in freely moving mice

Bioluminescence imaging (BLI) of gene expression in live animals is a powerful method for monitoring development, tumor growth, infections, healing, and other progressive, long-term biological processes. BLI remains an effective approach for reducing the number of animals needed to monitor dynamic changes in gene activity because images can be captured repeatedly from the same animals. When examining these ongoing changes, it is sometimes necessary to remove rhythmic effects on the bioluminescence signal caused by the circadian clock's daily modulation of gene expression. Furthermore, BLI using freely moving animals remains limited because the standard procedures can alter normal behaviors. Another obstacle with conventional BLI of animals is that luciferin, the firefly luciferase substrate, is usually injected into mice that are then imaged while anesthetized. Unfortunately, the luciferase signal declines rapidly during imaging as luciferin is cleared from the body. Alternatively, mice are imaged after they are surgically implanted with a pump or connected to a tether to deliver luciferin, but stressors such as this surgery and anesthesia can alter physiology, behavior, and the actual gene expression being imaged. Consequently, we developed a strategy that minimizes animal exposure to stressors before and during sustained BLI of freely moving unanesthetized mice. This technique was effective when monitoring expression of the Per1 gene that serves in the circadian clock timing mechanism and was previously shown to produce circadian bioluminescence rhythms in live mice. We used hairless albino mice expressing luciferase that were allowed to drink luciferin and engage in normal behaviors during imaging with cooled electron-multiplying-CCD cameras. Computer-aided image selection was developed to measure signal intensity of individual mice each time they were in the same posture, thereby providing comparable measurements over long intervals. This imaging procedure, performed primarily during the animal's night, is compatible with entrainment of the mouse circadian timing system to the light cycle while allowing sampling at multi-day intervals to monitor long-term changes. When the circadian expression of a gene is known, this approach provides an effective alternative to imaging immobile anesthetized animals and can removing noise caused by circadian oscillations and body movements that can degrade data collected during long-term imaging studies.

Useful genes for predicting the efficacy of transarterial chemoembolization in hepatocellular carcinoma

Transarterial chemoembolization (TACE) is generally used to treat patients with hepatocellular carcinoma (HCC), a common and deadly cancer; however, its efficacy varies according to factors such as tumor volume, stage, serum alpha-fetoprotein level, and chosen feeding artery. In addition, gene-related factors have been recently suggested to be involved in the regulation and prediction of TACE outcomes. Accordingly, genes could serve as effective biomarkers to select patients who can benefit from TACE. These gene-related factors can activate signaling pathways affecting cancer cell survival while regulating the epithelial-mesenchymal transition, angiogenesis, and the tumor microenvironment, all directly associated with tumor progression, thereby affecting TACE efficacy. Moreover, this disordered gene expression is associated with poor prognosis in patients with HCC, including TACE resistance, postoperative recurrence, and metastasis. To identify the exact relationship between various genes and TACE efficacy, this review summarizes the involvement of protein-coding and non-coding genes and single nucleotide polymorphisms in TACE efficacy for predicting the efficacy of TACE; the present findings may help improve the efficacy of TACE in clinical settings.

Sleep Disorders and Quality of Life in Patients With Cancer: Prospective Observational Study of the Rafael Institute

BACKGROUND

Sleep disorders are a common occurrence in the general population. Yet today, it is clearly agreed that sleep disorders represent both a cancer risk factor and a biological consequence of the of the activation of the immuno-inflammatory system induced by cancer itself.

OBJECTIVE

The aim of this study was to assess the impact of sleep disorders on quality of life and identify the type of disorder and its causes in order to offer an adapted and personalized care plan.

METHODS

In a survey completed during the COVID-19 lockdown, 2000 hours of interviews were collected by remote consultations. During these calls, we administered a sleep questionnaire. This questionnaire was inspired by the STOP-BANG questionnaire and enquired about 6 items. The demographic details of each patient (eg, age and sex), the nature of the pathology, their past treatments, the ongoing cancer treatment, the mood, whether or not the patient is anxious or depressed, and the use of sleeping drug pills were analyzed. A univariate analysis was performed according to the presence or absence of fatigue. Chi-square test was applied to assess possible differences of variables' link to sleep disturbance between patients complaining of fatigue and those without fatigue. The same test was then used to analyze patients on hormone therapy and those with no hormone therapy for 2 types of cancer-breast cancer and prostate cancer.

RESULTS

A total of 905 patients were prospectively included in this study. The average age was 66.7 (5 SD) years, and 606 (67%) patients were women; 142 patients declared being overweight. Breast cancer was the most frequently reported cancer. Nocturnal awakening was reported by 70% (n=633), fatigue by 50% (n=452), difficulty falling asleep by 38% (n=343), snoring reported by an independent observer in 38% (n=343), and apnea reported by an independent observer in 9% (n=81) of the patients. The univariate analysis showed that the feeling of tiredness was significantly greater in patients reporting difficulty falling asleep (P≥.99), pain (P<.001), and frequent awakening (P<.001), as well as in patients who were not receiving cancer treatment (P<.001). The univariate analysis showed that patients who were receiving breast cancer treatment and were under hormone therapy reported difficulty falling asleep (P=.04) and pain (P=.05). In a univariate analysis of patients treated for prostate cancer, being overweight was the only factor reported that had a statistically significant value.

CONCLUSIONS

Our preliminary data support and are consistent with data in the literature regarding the importance of sleep disorders in oncology. This justifies the usefulness of a diagnosis and early treatment of sleep disorders in patients with cancer. The Rafael Institute sleep observatory will enable patients to be identified and treated.

Effect of the Citrus Flavone Nobiletin on Circadian Rhythms and Metabolic Syndrome

The importance of the circadian clock in maintaining human health is now widely acknowledged. Dysregulated and dampened clocks may be a common cause of age-related diseases and metabolic syndrome Thus, circadian clocks should be considered as therapeutic targets to mitigate disease symptoms. This review highlights a number of dietary compounds that positively affect the maintenance of the circadian clock. Notably the polymethoxyflavone nobiletin has shown some encouraging results in pre-clinical experiments. Although many more experiments are needed to fully elucidate its exact mechanism of action, it is a promising candidate with potential as a chronotherapeutic agent.

Chronotherapy: Circadian Rhythms and Their Influence in Cancer Therapy

Living organisms present rhythmic fluctuations every 24 h in their behavior and metabolism to anticipate changes in the environment. These fluctuations are controlled by a very complex molecular mechanism, the circadian clock, that regulates the expression of multiple genes to ensure the right functioning of the body. An individual's circadian system is altered during aging, and this is related to numerous age-associated pathologies and other alterations that could contribute to the development of cancer. Nowadays, there is an increasing interest in understanding how circadian rhythms could be used in the treatment of cancer. Chronotherapy aims to understand the impact that biological rhythms have on the response to a therapy to optimize its action, maximize health benefits and minimize possible adverse effects. Clinical trials so far have confirmed that optimal timing of treatment with chemo or immunotherapies could decrease drug toxicity and increase efficacy. Instead, chronoradiotherapy seems to minimize treatment-related symptoms rather than tumor progression or patient survival. In addition, potential therapeutic targets within the molecular clock have also been identified. Therefore, results of the application of chronotherapy in cancer therapy until now are challenging, feasible, and could be applied to clinical practice to improve cancer treatment without additional costs. However, different limitations and variables such as age, sex, or chronotypes, among others, should be overcome before chronotherapy can really be put into clinical practice.

Progress of phototherapy for osteosarcoma and application prospect of blue light photobiomodulation therapy

Osteosarcoma (OS) is the most common primary malignant bone tumor that mainly affects the pediatric and adolescent population; limb salvage treatment has become one of the most concerned and expected outcomes of OS patients recently. Phototherapy (PT), as a novel, non-invasive, and efficient antitumor therapeutic approach including photodynamic therapy (PDT), photothermal therapy (PTT), and photobiomodulation therapy (PBMT), has been widely applied in superficial skin tumor research and clinical treatment. OS is the typical deep tumor, and its phototherapy research faces great limitations and challenges. Surprisingly, pulse mode LED light can effectively improve tissue penetration and reduce skin damage caused by high light intensity and has great application potential in deep tumor research. In this review, we discussed the research progress and related molecular mechanisms of phototherapy in the treatment of OS, mainly summarized the status quo of blue light PBMT in the scientific research and clinical applications of tumor treatment, and outlooked the application prospect of pulsed blue LED light in the treatment of OS, so as to further improve clinical survival rate and prognosis of OS treatment and explore corresponding cellular mechanisms.

Circadian Rhythm Disruption Increases Tumor Growth Rate and Accumulation of Myeloid-Derived Suppressor Cells

Circadian rhythm disruption is implicated in the initiation and progression of many diseases, including cancer. External stimuli, such as sunlight, serve to synchronize physiological processes and cellular functions to a 24-h cycle. The immune system is controlled by circadian rhythms, and perturbation of these rhythms can potentially alter the immune response to infections and tumors. The effect of circadian rhythm disruption on the immune response to tumors remains unclear. Specifically, the effects of circadian disruption (CD) on immunosuppressive cell types within the tumor, such as myeloid-derived suppressor cells (MDSCs), are unknown. In this study, a shifting lighting schedule is used to disrupt the circadian rhythm of mice. After acclimation to lighting schedules, mice are inoculated with 4T1 or B16-F10 tumors. Tumor growth is increased in mice housed under circadian disrupting lighting conditions compared to standard lighting conditions. Analysis of immune populations within the spleen and tumor shows an increased accumulation of MDSCs within these tissues, suggesting that MDSC mediated immunosuppression plays a role in the enhanced tumor growth caused by circadian disruption. This paves the way for future studies of the effects of CD on immunosuppression in cancer.

Relationships Between Serum Cortisol, RAGE-Associated s100A8/A9 Levels, and Self-Reported Cancer-Related Distress in Women With Nonmetastatic Breast Cancer

OBJECTIVE

Elevated inflammation and psychological distress in patients with breast cancer (BCa) have been related to poorer health outcomes. Regulation of the hypothalamic-pituitary-adrenal axis and signaling of the receptor for advanced glycation end products (RAGE) are important in the inflammatory response and have been associated with increased stress and poorer health outcomes in patients with cancer. This study examined relationships among circulating cortisol, a measure of hypothalamic-pituitary-adrenal axis activity and physiological stress; s100A8/A9, a RAGE ligand and emerging cancer-related biological measure; and self-reported cancer-related distress.

METHODS

Patients with BCa ( N = 183, stages 0-IIIb) were recruited 2 to 10 weeks after surgery but before receiving adjuvant therapies. Participants provided blood samples, from which serum cortisol and s100A8/A9 levels were determined, and completed a psychosocial questionnaire. Regression analyses, adjusting for age, cancer stage, time since surgery, race, and menopausal status, were conducted examining the relationships between cortisol, s100A8/A9, and cancer-related distress (Impact of Event Scale [IES]-Revised).

RESULTS

Cortisol and s100A8/A9 levels were positively related ( β = 0.218, t (112) = 2.332, p = .021), although the overall model was not significant. Cortisol levels were also positively associated with IES-Intrusions ( β = 0.192, t (163) = 2.659, p = .009) and IES-Hyperarousal subscale scores ( β = 0.171, t (163) = 2.304, p = .022).

CONCLUSIONS

Patients with higher cortisol levels also reported higher s100A8/A9 levels and more cancer-related distress. The relationship between cortisol and s100A8/A9 supports a link between the stress response and proinflammatory physiological processes known to predict a greater metastatic risk in BCa. Stress processes implicated in cancer biology are complex, and replication and extension of these initial findings are important.

Circadian clock synchrony and chronotherapy opportunities in cancer treatment

Cell-autonomous, tissue-specific circadian rhythms in gene expression and cellular processes have been observed throughout the human body. Disruption of daily rhythms by mistimed exposure to light, food intake, or genetic mutation has been linked to cancer development. Some medications are also more effective at certain times of day. However, a limited number of clinical studies have examined daily rhythms in the patient or drug timing as treatment strategies. This review highlights advances and challenges in cancer biology as a function of time of day. Recent evidence for daily rhythms and their entrainment in tumors indicate that personalized medicine should include understanding and accounting for daily rhythms in cancer patients.

Sleep Disruption and Cancer: Chicken or the Egg?

Sleep is a nearly ubiquitous phenomenon across the phylogenetic tree, highlighting its essential role in ensuring fitness across evolutionary time. Consequently, chronic disruption of the duration, timing, or structure of sleep can cause widespread problems in multiple physiological systems, including those that regulate energy balance, immune function, and cognitive capacity, among others. Many, if not all these systems, become altered throughout the course of cancer initiation, growth, metastatic spread, treatment, and recurrence. Recent work has demonstrated how changes in sleep influence the development of chronic diseases, including cancer, in both humans and animal models. A common finding is that for some cancers (e.g., breast), chronic disruption of sleep/wake states prior to disease onset is associated with an increased risk for cancer development. Additionally, sleep disruption after cancer initiation is often associated with worse outcomes. Recently, evidence suggesting that cancer itself can affect neuronal circuits controlling sleep and wakefulness has accumulated. Patients with cancer often report difficulty falling asleep, difficulty staying asleep, and severe fatigue, during and even years after treatment. In addition to the psychological stress associated with cancer, cancer itself may alter sleep homeostasis through changes to host physiology and via currently undefined mechanisms. Moreover, cancer treatments (e.g., chemotherapy, radiation, hormonal, and surgical) may further worsen sleep problems through complex biological processes yet to be fully understood. This results in a “chicken or the egg” phenomenon, where it is unclear whether sleep disruption promotes cancer or cancer reciprocally disrupts sleep. This review will discuss existing evidence for both hypotheses and present a framework through which the interactions between sleep and cancer can be dissociated and causally investigated.

Foundations of circadian medicine

The circadian clock is an evolutionarily highly conserved endogenous timing program that structures physiology and behavior according to the time of day. Disruption of circadian rhythms is associated with many common pathologies. The emerging field of circadian medicine aims to exploit the mechanisms of circadian physiology and clock-disease interaction for clinical diagnosis, treatment, and prevention. In this Essay, we outline the principle approaches of circadian medicine, highlight the development of the field in selected areas, and point out open questions and challenges. Circadian medicine has unambiguous health benefits over standard care but is rarely utilized. It is time for clock biology to become an integrated part of translational research.

Knockdown of UCHL3 inhibits esophageal squamous cell carcinoma progression by reducing CRY2 methylation

UCHL3 (Ubiquitin carboxyl-terminal hydrolase L3), a member of deubiquitinating enzymes, has been implicated in various cancers. However, the role of UCHL3 in esophageal squamous cell carcinoma (ESCC) remains unknown. In the current study, we aimed to investigate the role of UCHL3 in ESCC growth and migration, and whether UCHL3 could modulate CRY2 methylation through FOXM1. The expression of UCHL3 and CRY2 in ESCC tissues was assessed using qRT-PCR, western blotting and immunohistochemistry (IHC). Cell viability was determined by CCK-8 and colony formation assays. Hoechst 33342 and flow cytometry were used to detect cell apoptosis. Transwell assay was performed to investigate cell migration and invasion. In vivo animal model was used to assess cell tumorigenesis. Methylation-Specific PCR (MSP) was applied to detect CRY2 methylation in the promoter region. The results showed that UCHL3 expression was elevated in ESCC tissues and cells, while CRY2 expression was decreased. UCHL3 silencing inhibited cell viability, invasion, migration and induced cell apoptosis in vitro, repressed tumor growth in vivo, and increased CRY2 expression and decreased FOXM1 expression. In addition, UCHL3 knockdown decreased CRY2 methylation through downregulating FOXM1, leading to an increase in the expression of CRY2. Moreover, CRY2 silencing abolished UCHL3 deficiency-mediated inhibition in cell growth and migration. In summary, this study reveals that knockdown of UCHL3 inhibits ESCC growth and migration by reducing CRY2 methylation through downregulation of FOXM1 expression.

The Circadian Clock and Cancer: Links between Circadian Disruption and Disease Pathology

There is growing evidence that disruption of our 24-hour clock increases our risk for acquiring several diseases and disorders. One of these diseases is cancer. While the mechanistic links between circadian clock disruption and cancer initiation or progression are an active area of study, significantly more work needs to be done to understand the molecular substrates involved. Of particular complexity remains the functions of the clock in individual cells during the process of transformation (cancer initiation) vs. the functions of the clock in tumor-surrounding stroma in the process of tumor progression or metastasis. Indeed, the nexus of cellular circadian dynamics, metabolism, and carcinogenesis is drawing more attention, and many new studies are now highlighting the critical role of circadian rhythms and clock proteins in cancer prevention. In this brief review, we cover some of the basic mechanisms reported to link circadian disruption and cancer at the level of gene expression and metabolism. We also review some of the human studies addressing circadian disruption and cancer incidence as well as some controlled laboratory studies connecting the two in pre-clinical models. Finally, we discuss the tremendous opportunity to use circadian approaches for future prevention and treatment in the context of cancer in specific organs.

Potential effects of shift work on skin autoimmune diseases

Shift work is associated with systemic chronic inflammation, impaired host and tumor defense and dysregulated immune responses to harmless antigens such as allergens or auto-antigens. Thus, shift workers are at higher risk to develop a systemic autoimmune disease and circadian disruption with sleep impairment seem to be the key underlying mechanisms. Presumably, disturbances of the sleep-wake cycle also drive skin-specific autoimmune diseases, but epidemiological and experimental evidence so far is scarce. This review summarizes the effects of shift work, circadian misalignment, poor sleep, and the effect of potential hormonal mediators such as stress mediators or melatonin on skin barrier functions and on innate and adaptive skin immunity. Human studies as well as animal models were considered. We will also address advantages and potential pitfalls in animal models of shift work, and possible confounders that could drive skin autoimmune diseases in shift workers such as adverse lifestyle habits and psychosocial influences. Finally, we will outline feasible countermeasures that may reduce the risk of systemic and skin autoimmunity in shift workers, as well as treatment options and highlight outstanding questions that should be addressed in future studies.

BMAL1 induces colorectal cancer metastasis by stimulating exosome secretion

BACKGROUND

To adapt to daily changes in the external environment, organisms have developed circadian rhythm systems with a period of approximately 24 h. Many studies have reported that both circadian rhythms and exosomes play important roles in the development and metastasis of tumors. However, whether circadian clock genes can affect the progression of tumors by regulating exosomes remains unclear.

METHODS AND RESULTS

In this study, we isolated exosomes from the supernatant of human colorectal cancer (CRC) cells, including SW480, SW620, and HCT116 cells, by differential centrifugation and characterized exosomes by transmission electron microscopy, nanoparticle tracking analysis, and Western blot analysis. Then, we found that exosomes derived from SW480, SW620 and HCT116 cells could promote the migration of HCT116 and human umbilical vein endothelial cells. Exosomes derived from SW620 cells showed increased stimulating effects when we increased the expression of BMAL1, a core circadian protein. In contrast, exosomes derived from SW480 and HCT116 cells showed decreased stimulating effects when we knocked down the expression of BMAL1. Furthermore, we discovered that BMAL1 promotes the release of exosomes by HCT116 and SW620 cells. In addition, by luciferase assay, we confirmed that BMAL1 transcriptionally regulates the expression of Rab27a, a key molecule related to the secretion of exosomes.

CONCLUSIONS

Our data reveal a new mechanism by which BMAL1 induces CRC metastasis by stimulating exosome secretion. This finding may help further clarify the role of circadian rhythm in the progression of CRC.

Circadian clock and cell cycle: Cancer and chronotherapy

The circadian clock is an endogenous timing system that ensures that various physiological processes have nearly 24 h circadian rhythms, including cell metabolism, division, apoptosis, and tumor production. In addition, results from animal models and molecular studies underscore emerging links between the cell cycle and the circadian clock. Mutations in the core genes of the circadian clock' can disrupt the cell cycle, which in turn increases the possibility of tumors. At present, tumor chronotherapy, which relies on a circadian clock mechanism, is developing rapidly for optimizing the time of drug administration in tumor treatment to improve drug efficacy and safety. However, the relationship between the circadian clock and the cell cycle is extremely complicated. This review summarizes the possible connection between the circadian clock and the cell cycle. In addition, the review provides evidence of the influence of the circadian clock on senescence and cancer.

Circadian clock, carcinogenesis, chronochemotherapy connections

The circadian clock controls the expression of nearly 50% of protein coding genes in mice and most likely in humans as well. Therefore, disruption of the circadian clock is presumed to have serious pathological effects including cancer. However, epidemiological studies on individuals with circadian disruption because of night shift or rotating shift work have produced contradictory data not conducive to scientific consensus as to whether circadian disruption increases the incidence of breast, ovarian, prostate, or colorectal cancers. Similarly, genetically engineered mice with clock disruption do not exhibit spontaneous or radiation-induced cancers at higher incidence than wild-type controls. Because many cellular functions including the cell cycle and cell division are, at least in part, controlled by the molecular clock components (CLOCK, BMAL1, CRYs, PERs), it has also been expected that appropriate timing of chemotherapy may increase the efficacy of chemotherapeutic drugs and ameliorate their side effect. However, empirical attempts at chronochemotherapy have not produced beneficial outcomes. Using mice without and with human tumor xenografts, sites of DNA damage and repair following treatment with the anticancer drug cisplatin have been mapped genome-wide at single nucleotide resolution and as a function of circadian time. The data indicate that mechanism-based studies such as these may provide information necessary for devising rational chronochemotherapy regimens.

Adjusting the Molecular Clock: The Importance of Circadian Rhythms in the Development of Glioblastomas and Its Intervention as a Therapeutic Strategy

Gliomas are solid tumors of the central nervous system (CNS) that originated from different glial cells. The World Health Organization (WHO) classifies these tumors into four groups (I-IV) with increasing malignancy. Glioblastoma (GBM) is the most common and aggressive type of brain tumor classified as grade IV. GBMs are resistant to conventional therapies with poor prognosis after diagnosis even when the Stupp protocol that combines surgery and radiochemotherapy is applied. Nowadays, few novel therapeutic strategies have been used to improve GBM treatment, looking for higher efficiency and lower side effects, but with relatively modest results. The circadian timing system temporally organizes the physiology and behavior of most organisms and daily regulates several cellular processes in organs, tissues, and even in individual cells, including tumor cells. The potentiality of the function of the circadian clock on cancer cells modulation as a new target for novel treatments with a chronobiological basis offers a different challenge that needs to be considered in further detail. The present review will discuss state of the art regarding GBM biology, the role of the circadian clock in tumor progression, and new chrono-chemotherapeutic strategies applied for GBM treatment.

Adjusting the Molecular Clock: The Importance of Circadian Rhythms in the Development of Glioblastomas and Its Intervention as a Therapeutic Strategy

Gliomas are solid tumors of the central nervous system (CNS) that originated from different glial cells. The World Health Organization (WHO) classifies these tumors into four groups (I-IV) with increasing malignancy. Glioblastoma (GBM) is the most common and aggressive type of brain tumor classified as grade IV. GBMs are resistant to conventional therapies with poor prognosis after diagnosis even when the Stupp protocol that combines surgery and radiochemotherapy is applied. Nowadays, few novel therapeutic strategies have been used to improve GBM treatment, looking for higher efficiency and lower side effects, but with relatively modest results. The circadian timing system temporally organizes the physiology and behavior of most organisms and daily regulates several cellular processes in organs, tissues, and even in individual cells, including tumor cells. The potentiality of the function of the circadian clock on cancer cells modulation as a new target for novel treatments with a chronobiological basis offers a different challenge that needs to be considered in further detail. The present review will discuss state of the art regarding GBM biology, the role of the circadian clock in tumor progression, and new chrono-chemotherapeutic strategies applied for GBM treatment.

NR1D1 suppressed the growth of ovarian cancer by abrogating the JAK/STAT3 signaling pathway

Background

Nuclear receptor subfamily 1 group D member 1 (NR1D1), a nuclear receptor associated with a variety of physiological processes, has a low level in ovarian cancer tissues compared with adjacent normal tissues. However, its role in ovarian cancer remains unclear.

Methods

The level of NR1D1 in ovarian cancer cells was determined by quantitative real-time PCR. Its role in ovarian cancer was explored through gain-of-function and lose-of-function. Cell growth was evaluated by CCK8 assay, immunofluorescence and flow cytometry. Western blot was conducted to assess the activation of JAK/STAT3 signaling pathway. A xenograft model of ovarian cancer was established to explore the role of NR1D1 in vivo.

Results

Up-regulation of NR1D1 repressed the ovarian cancer cell proliferation and induced cell cycle arrest and apoptosis, while silencing NR1D1 promoted their proliferation and G1/S transition. In addition, the JAK/STAT3 signaling pathway, an intracellular signal transduction closely associated with cancer progression, was inhibited by NR1D1. Consistently, xenografts with NR1D1 over-expression grew more slowly in vivo than the controls. Furthermore, NR1D1 up-regulated the expression of suppressor of cytokine signaling 3 (SOCS3), an inhibitor of the JAK/STAT3 signaling pathway. Whereas, SOCS3 silencing abolished the function of NR1D1 over-expression on ovarian cancer growth and JAK/STAT3 signaling pathway.

Conclusions

NR1D1 up-regulated the expression of SOCS3, resulting in suppression of the JAK/STAT3 signaling pathway, thus retarding the growth of ovarian cancer cells. This study highlights a profound role of NR1D1 in the treatment of ovarian cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08597-8.

Clock at the Core of Cancer Development

To synchronize various biological processes with the day and night cycle, most organisms have developed circadian clocks. This evolutionarily conserved system is important in the temporal regulation of behavior, physiology and metabolism. Multiple pathological changes associated with circadian disruption support the importance of the clocks in mammals. Emerging links have revealed interplay between circadian clocks and signaling networks in cancer. Understanding the cross-talk between the circadian clock and tumorigenesis is imperative for its prevention, management and development of effective treatment options. In this review, we summarize the role of the circadian clock in regulation of one important metabolic pathway, insulin/IGF1/PI3K/mTOR signaling, and how dysregulation of this metabolic pathway could lead to uncontrolled cancer cell proliferation and growth. Targeting the circadian clock and rhythms either with recently discovered pharmaceutical agents or through environmental cues is a new direction in cancer chronotherapy. Combining the circadian approach with traditional methods, such as radiation, chemotherapy or the recently developed, immunotherapy, may improve tumor response, while simultaneously minimizing the adverse effects commonly associated with cancer therapies.

Clocks, cancer, and chronochemotherapy

The circadian clock coordinates daily rhythmicity of biochemical, physiologic, and behavioral functions in humans. Gene expression, cell division, and DNA repair are modulated by the clock, which gives rise to the hypothesis that clock dysfunction may predispose individuals to cancer. Although the results of many epidemiologic and animal studies are consistent with there being a role for the clock in the genesis and progression of tumors, available data are insufficient to conclude that clock disruption is generally carcinogenic. Similarly, studies have suggested a circadian time-dependent efficacy of chemotherapy, but clinical trials of chronochemotherapy have not demonstrated improved outcomes compared with conventional regimens. Future hypothesis-driven and discovery-oriented research should focus on specific interactions between clock components and carcinogenic mechanisms to realize the full clinical potential of the relationship between clocks and cancer.

Time to fight: targeting the circadian clock molecular machinery in cancer therapy

The circadian clock regulates a wide range of molecular pathways and biological processes. The expression of clock genes is often altered in cancer, fostering tumor initiation and progression. Inhibition and activation of core circadian clock genes, as well as treatments that restore circadian rhythmicity, have been successful in counteracting tumor growth in different experimental models. Here, we provide an up-to-date overview of studies that show the therapeutic effects of targeting the clock molecular machinery in cancer, both genetically and pharmacologically. We also highlight future areas for progress that offer a promising path towards innovative anticancer strategies. Substantial limitations in the current understanding of the complex interplay between the circadian clock and cancer in vivo need to be addressed in order to allow clock-targeting therapies in cancer.

Valerian and valeric acid inhibit growth of breast cancer cells possibly by mediating epigenetic modifications

Valerian root (Valeriana officinalis) is a popular and widely available herbal supplement used to treat sleeping disorders and insomnia. The herb's ability to ameliorate sleep dysfunction may signify an unexplored anti-tumorigenic effect due to the connection between circadian factors and tumorigenesis. Of particular interest are the structural similarities shared between valeric acid, valerian's active chemical ingredient, and certain histone deacteylase (HDAC) inhibitors, which imply that valerian may play a role in epigenetic gene regulation. In this study, we tested the hypothesis that the circadian-related herb valerian can inhibit breast cancer cell growth and explored epigenetic changes associated with valeric acid treatment. Our results showed that aqueous valerian extract reduced growth of breast cancer cells. In addition, treatment of valeric acid was associated with decreased breast cancer cell proliferation, migration, colony formation and 3D formation in vitro in a dose- and time-dependent manner, as well as reduced HDAC activity and a global DNA hypomethylation. Overall, these findings demonstrate that valeric acid can decrease the breast cancer cell proliferation possibly by mediating epigenetic modifications such as the inhibition of histone deacetylases and alterations of DNA methylation. This study highlights a potential utility of valeric acid as a novel HDAC inhibitor and a therapeutic agent in the treatment of breast cancer.

Transcriptome analysis of the circadian clock gene BMAL1 deletion with opposite carcinogenic effects

We have previously reported that the deletion of BMAL1 gene has opposite effects in respect to its contribution to the pathways that are effective in the multistage carcinogenesis process. BMAL1 deletion sensitized nearly normal breast epithelial (MCF10A) and invasive breast cancer cells (MDA-MB-231) to cisplatin- and doxorubicin-induced apoptosis, while this deletion also aggravated the invasive potential of MDA-MB-231 cells. However, the mechanistic relationship of the seemingly opposite contribution of BMAL1 deletion to carcinogenesis process is not known at genome-wide level. In this study, an RNA-seq approach was taken to uncover the differentially expressed genes (DEGs) and pathways after treating BMAL1 knockout (KO) or wild-type (WT) MDA-MB-231 cells with cisplatin and doxorubicin to initiate apoptosis. Gene set enrichment analysis with the DEGs demonstrated that enrichment in multiple genes/pathways contributes to sensitization to cisplatin- or doxorubicin-induced apoptosis in BMAL1-dependent manner. Additionally, our DEG analysis suggested that non-coding transcript RNA (such as lncRNA and processed pseudogenes) may have role in cisplatin- or doxorubicin-induced apoptosis. Protein-protein interaction network obtained from common DEGs in cisplatin and doxorubicin treatments revealed that GSK3β, NACC1, and EGFR are the principal genes regulating the response of the KO cells. Moreover, the analysis of DEGs among untreated BMAL1 KO and WT cells revealed that epithelial-mesenchymal transition genes are up-regulated in KO cells. As a negative control, we have also analyzed the DEGs following treatment with an endoplasmic reticulum (ER) stress-inducing agent, tunicamycin, which was affected by BMAL1 deletion minimally. Collectively, the present study suggests that BMAL1 regulates many genes/pathways of which the alteration in BMAL1 KO cells may shed light on pleotropic phenotype observed.

Shift Work and Breast Cancer

The rates of shift work outside of daylight hours have increased in recent years, and nighttime shift work is now considered a potential carcinogenic occupational exposure. Light at night exposure, lower melatonin production, and the production of stress-related mediators disrupt normal sleep–wake cycles. Women who work lower-wage jobs and part-time workers whose shifts are determined entirely by their supervisors (rotating shifts) may be subject to stress related to efforts to align childcare and other needs with the unpredictable nature of rotating shift work. The causal link between breast cancer and the sleep cycle or circadian disruption are yet to be established; however, disruption of the circadian cycles by light at night exposure or chronic exposure to stress-related mediators have all been linked to the increased risk of breast cancer. We review the existing literature on shift work and breast cancer, identify knowledge gaps, and suggest future directions for research.

Circadian disruption promotes tumor-immune microenvironment remodeling favoring tumor cell proliferation

Circadian disruption negatively affects physiology, posing a global health threat that manifests in proliferative, metabolic, and immune diseases, among others. Because outputs of the circadian clock regulate daily fluctuations in the immune response, we determined whether circadian disruption results in tumor-associated immune cell remodeling, facilitating tumor growth. Our findings show that tumor growth rate increased and latency decreased under circadian disruption conditions compared to normal light-dark (LD) schedules in a murine melanoma model. Circadian disruption induced the loss or inversion of daily patterns of M1 (proinflammatory) and M2 (anti-inflammatory) macrophages and cytokine levels in spleen and tumor tissues. Circadian disruption also induced (i) deregulation of rhythmic expression of clock genes and (ii) of cyclin genes in the liver, (iii) increased CcnA2 levels in the tumor, and (iv) dampened expression of the cell cycle inhibitor p21^WAF/CIP1 , all of which contribute to a proliferative phenotype.

Cancer in the Fourth Dimension: What Is the Impact of Circadian Disruption?

Circadian rhythms integrate many physiological pathways, helping organisms to align the timing of various internal processes to daily cycles in the external environment. Disrupted circadian rhythmicity is a prominent feature of modern society, and has been designated as a probable carcinogen. Here, we review multiple studies, in humans and animal models, that suggest a causal effect between circadian disruption and increased risk of cancer. We also discuss the complexity of this connection, which may depend on the cellular context. SIGNIFICANCE: Accumulating evidence points to an adverse effect of circadian disruption on cancer incidence and progression, indicating that time of day could influence the effectiveness of interventions targeting cancer prevention and management.

Circadian Rhythm Is Disrupted by ZNF704 in Breast Carcinogenesis

Copy number gain in chromosome 8q21 is frequently detected in breast cancer, yet the oncogenic potential underlying this amplicon in breast carcinogenesis remains to be delineated. We report here that ZNF704, a gene mapped to 8q21, is recurrently amplified in various malignancies including breast cancer. ZNF704 acted as a transcriptional repressor and interacted with the transcriptional corepressor SIN3A complex. Genome-wide interrogation of transcriptional targets revealed that the ZNF704/SIN3A complex represses a panel of genes including PER2 that are critically involved in the function of the circadian clock. Overexpression of ZNF704 prolonged the period and dampened the amplitude of the circadian clock. ZNF704 promoted the proliferation and invasion of breast cancer cells in vitro and accelerated the growth and metastasis of breast cancer in vivo. Consistently, the level of ZNF704 expression inversely correlated with that of PER2 in breast carcinomas, and high level of ZNF704 correlated with advanced histologic grades, lymph node positivity, and poor prognosis of patients with breast cancer, especially those with HER2⁺ and basal-like subtypes. These results indicate that ZNF704 is an important regulator of the circadian clock and a potential driver for breast carcinogenesis. SIGNIFICANCE: This study indicates that ZNF704 could be a potential oncogenic factor, disrupting circadian rhythm of breast cancer cells and contributing to breast carcinogenesis.

Low circadian clock genes expression in cancers: A meta-analysis of its association with clinicopathological features and prognosis

Background

Per1, Per2, Per3, Cry1, Cry2, Bmal1, Npas2 and CLOCK genes are the eight core circadian clock genes. Low expression of these circadian clock genes plays an important role in the progression of cancers. However, its clinicopathological and prognostic value in patients with cancers remains controversial and inconclusive. We performed a meta-analysis of studies assessing the clinicopathological and prognostic significance of low expression of these genes in cancers.

Methods

Relevant studies were searched from the Cochrane Central Register of Controlled Trials, Embase, EBSCO, Ovid, PubMed, Science Direct, Wiley Online Library database, CNKI and Wan Fang database. The meta-analysis was performed by using STATA version 12 software. A random-effect model was employed to evaluate all pooled hazard ratios (HRs) and odd ratios (ORs).

Results

A total of 36 studies comprising 7476 cases met the inclusion criteria. Meta-analysis suggested that low expression of Per1 was associated with poor differentiation (Per1: OR=2.30, 95%CI: 1.36∼3.87, P=0.002) and deeper invasion depth (Per1: OR=2.12, 95%CI: 1.62∼2.77, Ρ<0.001); low Per2 expression was correlated with poor differentiation (Per2: OR=2.41, 95%CI: 1.53∼3.79, Ρ<0.001), worse TNM stage (Per2:OR=3.47, 95%CI: 1.88∼6.42, P<0.001) and further metastasis (Per2:OR=2.35, 95%CI: 1.35∼4.11, Ρ=0.003). Furthermore, the results revealed that low expressions of Per1 and Per2 were also correlated with poor overall survival of cancers (Per1: HR=1.35, 95%CI: 1.06∼1.72, P=0.014; Per2: HR=1.43, 95%CI: 1.10∼1.85, P=0.007). Subgroup analysis indicated that low Per1 and Per2 expressions were especially associated with poor prognosis of gastrointestinal caners (Per1: HR=1.33, 95%CI: 1.14∼1.55, Ρ<0.001, Ι²=4.2%; Per2: HR=1.62, 95%CI: 1.25∼2.18, P<0.001, I²=0.0%).

Conclusions

Our study suggested that low Per1, Per2 and Npas2 expression played a distinct and crucial role in progression of cancers. Low expressions of Per1 and Per2 could serve as unfavorable indicators for cancers prognosis, especially for gastrointestinal cancers.

Circadian rhythmicity of body temperature and metabolism

This article reviews the literature on the circadian rhythms of body temperature and whole-organism metabolism. The two rhythms are first described separately, each description preceded by a review of research methods. Both rhythms are generated endogenously but can be affected by exogenous factors. The relationship between the two rhythms is discussed next. In endothermic animals, modulation of metabolic activity can affect body temperature, but the rhythm of body temperature is not a mere side effect of the rhythm of metabolic thermogenesis associated with general activity. The circadian system modulates metabolic heat production to generate the body temperature rhythm, which challenges homeothermy but does not abolish it. Individual cells do not regulate their own temperature, but the relationship between circadian rhythms and metabolism at the cellular level is also discussed. Metabolism is both an output of and an input to the circadian clock, meaning that circadian rhythmicity and metabolism are intertwined in the cell.

Circadian rhythm impacts preclinical FDG-PET quantification in the brain, but not in xenograft tumors

The inner clock of biological organisms plays a pivotal role and has strong effects on metabolic processes such as glucose consumption. Since the commonly used positron emission tomography (PET) tracer ¹⁸F-flourodeoxygucose (FDG) is a glucose analogue, it is not surprising that the FDG distribution in mice and humans has been shown to succumb to daily rhythms. In preclinical studies, the circadian rhythm of animals is often not considered, and studies are performed at different times of day. Only a few studies have analyzed the effect of the circadian rhythm on FDG uptake in mice, and none of these studies included human tumor xenografts. Therefore, it is not known how strongly a preclinical tumor study is influenced by the time of day. In this work, the effect of the circadian rhythm on FDG uptake in human tumor xenografts and other organs was analyzed. CD1 nu/nu mice were kept for three weeks under a 12 h light/12 h dark rhythm and then injected s.c. with PC3 or A431 tumor cells. When the tumors had reached an appropriate volume, FDG-PET scans were performed on different animal groups (n = 4–5) every 4 h over a time period from 8 A.M. to 8 P.M. Tracer uptake in the tumors and in other organs was determined based on the PET scans and biodistribution studies. The standardized uptake value and %injected dose/cc of the tumors remained constant over the whole observed time period, and no statistically significant differences were determined according to the PET analysis. In the brain, we found a small but statistically significant increase from noon to 4 P.M., which led to a decrease in the tumor-to-brain ratio. No evidence for an effect of the circadian rhythm on FDG uptake could be found in subcutaneous tumors, however, in brain studies the circadian rhythm needs to be considered.

Overexpression of the clock gene Per2 suppresses oral squamous cell carcinoma progression by activating autophagy via the PI3K/AKT/mTOR pathway

The current studies reveal that the clock gene Per2 is expressed at lower levels in a variety of tumors and plays a significant tumor suppressor role. However, the biological functions and mechanism of Per2 in OSCC (OSCC: oral squamous cell carcinoma) remain unclear. In this study, OSCC cells with stable overexpression or silencing of Per2 were established to explore their biological functions and mechanism in vivo and in vitro. We discovered that the expression of Per2 decreases in OSCC cells. Overexpression of Per2 promoted autophagy and apoptosis in OSCC cells and inhibited proliferation. The opposite results were obtained in Per2-silenced OSCC cells. In Per2-overexpressing OSCC cells, the expression levels of PIK3CA, p-AKT, p-mTOR, p62 and Beclin1 were significantly reduced and the LC3B II/I ratio was significantly increased. In contrast, in Per2-silenced OSCC cells, the expression levels of PIK3CA, p-AKT, p-mTOR, p62 and Beclin1 were significantly enhanced and the LC3B II/I ratio was significantly reduced. When the AKT activator SC79 was added to Per2-overexpressing OSCC cells, the increased autophagy, apoptosis and decreased proliferation were significantly rescued. Furthermore, when autophinib, an autophagy inhibitor, was added to Per2-overexpressing OSCC cells, the decreased proliferation and increased apoptosis were significantly restored. An in vivo tumorigenesis assay also confirmed that overexpression of Per2 suppresses the growth of OSCC. In conclusion, our research results demonstrate that Per2 suppresses OSCC progression by motivating autophagy, as well as inhibiting cell proliferation and promoting apoptosis, which were mediated by autophagy, in a PI3K/AKT/mTOR pathway-dependent manner. Per2 could potentially be used as a valuable therapeutic marker for OSCC.

Loss of the clock gene Per1 promotes oral squamous cell carcinoma progression via the AKT/mTOR pathway

Current studies have shown that the clock gene Period 1 (Per1) is downregulated in various tumors and plays an important role in promoting tumor progression. However, the biological functions and mechanism of Per1 in tumors remain largely unknown. In this study, 86 specimens of oral squamous cell carcinoma (OSCC) tissues and adjacent noncancerous tissues were collected to determine the Per1 expression level and the clinical significance of Per1 expression. Per1 was stably inhibited or overexpressed in OSCC cells to investigate its function and mechanism in vitro and in vivo. We found that Per1 was remarkably downregulated in OSCC and that low Per1 expression was significantly associated with TNM clinical stage and poor prognosis of OSCC patients. Per1 overexpression in SCC15 OSCC cells (Per1-OE SCC15 cells) significantly promoted autophagy and apoptosis while inhibiting proliferation and the AKT/mTOR pathway. However, the results obtained in Per1-silenced TSCCA OSCC cells were opposite those obtained in Per1-OE SCC15 cells. After addition of the AKT activator SC79 to Per1-OE SCC15 cells, the increased autophagy and apoptosis as well as decreased proliferation were remarkably rescued. Furthermore, increased apoptosis was significantly rescued in Per1-OE SCC15 cells treated with the autophagy inhibitor autophinib. In vivo tumorigenicity assays also confirmed that Per1 overexpression suppressed tumor growth. Taken together, our findings demonstrate for the first time that Per1 promotes OSCC progression by inhibiting autophagy-mediated cell apoptosis and enhancing cell proliferation in an AKT/mTOR pathway-dependent manner, and Per1 could be used as a valuable therapeutic target for OSCC.

Circadian Genes as Therapeutic Targets in Pancreatic Cancer

Pancreatic cancer is one of the most lethal cancers worldwide due to its symptoms, early metastasis, and chemoresistance. Thus, the mechanisms contributing to pancreatic cancer progression require further exploration. Circadian rhythms are the daily oscillations of multiple biological processes regulated by an endogenous clock. Several evidences suggest that the circadian clock may play an important role in the cell cycle, cell proliferation and apoptosis. In addition, timing of chemotherapy or radiation treatment can influence the efficacy and toxicity treatment. Here, we revisit the studies on circadian clock as an emerging target for therapy in pancreatic cancer. We highlight those potential circadian genes regulators that are commonly affected in pancreatic cancer according to most recent reports.