CRY2 missense mutations suppress P53 and enhance cell growth

Circadian clock gene polymorphisms implicated in human pathologies

Circadian rhythms, ~24 h cycles of physiological and behavioral processes, can be synchronized by external signals (e.g., light) and persist even in their absence. Consequently, dysregulation of circadian rhythms adversely affects the well-being of the organism. This timekeeping system is generated and sustained by a genetically encoded endogenous mechanism composed of interlocking transcriptional/translational feedback loops that generate rhythmic expression of core clock genes. Genome-wide association studies (GWAS) and forward genetic studies show that SNPs in clock genes influence gene regulation and correlate with the risk of developing various conditions. We discuss genetic variations in core clock genes that are associated with various phenotypes, their implications for human health, and stress the need for thorough studies in this domain of circadian regulation.

Embracing cancer complexity: Hallmarks of systemic disease

The last 50 years have witnessed extraordinary developments in understanding mechanisms of carcinogenesis, synthesized as the hallmarks of cancer. Despite this logical framework, our understanding of the molecular basis of systemic manifestations and the underlying causes of cancer-related death remains incomplete. Looking forward, elucidating how tumors interact with distant organs and how multifaceted environmental and physiological parameters impinge on tumors and their hosts will be crucial for advances in preventing and more effectively treating human cancers. In this perspective, we discuss complexities of cancer as a systemic disease, including tumor initiation and promotion, tumor micro- and immune macro-environments, aging, metabolism and obesity, cancer cachexia, circadian rhythms, nervous system interactions, tumor-related thrombosis, and the microbiome. Model systems incorporating human genetic variation will be essential to decipher the mechanistic basis of these phenomena and unravel gene-environment interactions, providing a modern synthesis of molecular oncology that is primed to prevent cancers and improve patient quality of life and cancer outcomes.

Multi-omics and single-cell sequencing analyses reveal the potential significance of circadian pathways in cancer therapy

BACKGROUND

Circadian rhythm disturbance is an independent risk factor for cancer. However, few studies have been reported on circadian rhythm related genes (CRGs) in cancer, so it is important to further explore the impact of CRGs in pan-cancer.

RESEARCH DESIGN AND METHODS

The Cancer Genome Atlas database was used to collect cancer-related data such as copy number variation, single nucleotide variants, methylation, and survival differences. Immunohistochemistry (IHC) was used to verify the expression of circadian rhythm hub genes. The circadian pathway scores (CRS) were calculated using single-sample gene enrichment analysis. TIMER and GEPIA databases were used for immune-cell integration and assessment. Single-cell sequencing data was used to evaluate the abundance of CRS in tumor microenvironment cells.

RESULTS

In this study, we found that the expression of circadian pathway varies between tumors. CSNK1E was significantly up-regulated in most tumors and CRY2 was significantly down-regulated in most tumors. The protein interaction network suggested CRY2 as the core gene and IHC verified its significant low expression in KIRC. In addition, CRGs were found to be protective factors in most tumors and have the potential to act as specific immune markers in different tumors. CRS was significantly lower in abundance in most tumors. CRS was significantly associated with overall survival in tumor patients and associated with the expression of many immune cells in the tumor immune microenvironment. CRS is significantly associated with tumor mutational burden and microsatellite instability scores in most tumors and may serve as a potential immunotherapeutic marker.

CONCLUSIONS

The circadian rhythm pathway may be a breakthrough point in regulating the tumor microenvironment meanwhile a suitable immunotherapy method in the future.

Histone demethylase KDM4B accelerates the progression of glioblastoma via the epigenetic regulation of MYC stability

BACKGROUND

Glioblastoma (GBM) is the most malignant and invasive human brain tumor. Histone demethylase 4B (KDM4B) is abnormally expressed in GBM, but the molecular mechanisms by which KDM4B affects the malignant tumor progression are not well defined.

METHODS

GBM cell lines and xenograft tumor samples were subjected to quantitative PCR (qPCR), Western blot, immunohistochemical staining (IHC), as well as ubiquitination, immunoprecipitation (IP), and chromatin immunoprecipitation (ChIP) assays to investigate the role of KDM4B in the progression of GBM.

RESULTS

Here, we report that KDM4B is an epigenetic activator of GBM progression. Abnormal expression of KDM4B is correlated with a poor prognosis in GBM patients. In GBM cell lines, KDM4B silencing significantly inhibited cell survival, proliferation, migration, and invasion, indicating that KDM4B is essential for the anchorage-independent growth and tumorigenic activity of GBM cells. Mechanistically, KDM4B silencing led to downregulation of the oncoprotein MYC and suppressed the expression of cell cycle proteins and epithelial-to-mesenchymal transition (EMT)-related proteins. Furthermore, we found that KDM4B regulates MYC stability through the E3 ligase complex SCFFBXL3+CRY2 and epigenetically activates the transcription of CCNB1 by removing the repressive chromatin mark histone H3 lysine 9 trimethylation (H3K9me3). Finally, we provide evidence that KDM4B epigenetically activates the transcription of miR-181d-5p, which enhances MYC stability.

CONCLUSIONS

Our study has uncovered a KDM4B-dependent epigenetic mechanism in the control of tumor progression, providing a rationale for utilizing KDM4B as a promising therapeutic target for the treatment of MYC-amplified GBM.

Circadian Clock Dysregulation and Prostate Cancer: A Molecular and Clinical Overview

Circadian clock dysregulation has been implicated in various types of cancer and represents an area of growing research. However, the role of the circadian clock in prostate cancer has been relatively unexplored. This literature review will highlight the potential role of circadian clock dysregulation in prostate cancer by examining molecular, epidemiologic, and clinical data. The influence of melatonin, light, night shift work, chronotherapy, and androgen independence are discussed as they relate to the existing literature on their role in prostate cancer.

Four circadian rhythm-related genes predict incidence and prognosis in hepatocellular carcinoma

Circadian dysregulation can be involved in the development of malignant tumors, though its relationship with the progression of hepatocellular carcinoma is not yet fully understood. We identified genes related to circadian rhythms from the Cancer Genome Atlas (TCGA), measured gene expression, and conducted genomic difference analysis to construct a circadian rhythm-related signature. The resulting prognosis model proved to be an effective biomarker, as demonstrated by Kaplan-Meier survival analysis for both the training (n = 370, P = 2.687e-10) and external validation cohorts (n = 230, P = 1.45e-02). Further, we found that patients considered 'high risk', with an associated poor prognosis, displayed elevated levels of immune checkpoint genes and immune filtration. We also conducted functional enrichment, which indicated that the risk model showed a significant positive correlation with certain malignant phenotypes, including G2M checkpoint, MYC targets, and the MTORC1 signaling pathway. In summary, we identified a novel circadian rhythm-related signature allowing assessment of prognosis for hepatocellular carcinoma patients, and further can be used to predict immune infiltration sensitivity.

A methylbenzimidazole derivative regulates mammalian circadian rhythms by targeting Cryptochrome proteins

Background: Impairment of the circadian clock has been associated with numerous diseases, including sleep disorders and metabolic disease. Although small molecules that modulate clock function may form the basis of drug discovery of clock-related diseases, only a few compounds that selectively target core clock proteins have been identified. Three scaffolds were previously discovered as small-molecule activators of the clock protein Cryptochrome (CRY), and they have been providing powerful tools to understand and control the circadian clock system. Identifying new scaffolds will expand the possibilities of drug discovery. Methods: A methylbenzimidazole derivative TH401 identified from cell-based circadian screens was characterized. Effects of TH401 on circadian rhythms were evaluated in cellular assays. Functional assays and X-ray crystallography were used to elucidate the effects of the compound on CRY1 and CRY2 isoforms. Results: TH401 lengthened the period of circadian rhythms and stabilized both CRY1 and CRY2. The compound repressed Per2 reporter activity, which was reduced by Cry1 or Cry2 knockout and abolished by Cry1/Cry2 double knockout, indicating the dependence on CRY isoforms. Thermal shift assays showed slightly higher interaction of TH401 with CRY2 over CRY1. The crystal structure of CRY1 in complex with TH401 revealed a conformational change of the gatekeeper W399, which is involved in isoform-selectivity determination. Conclusions: The present study identified a new small molecule TH401 that targets both CRY isoforms. This compound has expanded the chemical diversity of CRY activators, and will ultimately aid in the development of therapeutics against circadian clock-related disorders.

CRY2 isoform selectivity of a circadian clock modulator with antiglioblastoma efficacy

The mammalian cryptochrome isoforms, CRY1 and CRY2, are core circadian clock regulators that work redundantly. Recent studies revealed distinct roles of these closely related homologs in clock output pathways. Isoform-selective control of CRY1 and CRY2 is critical for further understanding their redundant and distinct roles. KL001 was the first identified small-molecule CRY modulator that activates both CRY1 and CRY2. SHP656 is an orally available KL001 derivative and has shown efficacy in blood glucose control and inhibition of glioblastoma stem cell (GSC) growth in animal models. However, CRY isoform selectivity of SHP656 was uncharacterized, limiting understanding of the roles of CRY1 and CRY2. Here, we report the elucidation of CRY2 selectivity of SHP656. SHP656 lengthened cellular circadian period in a CRY2-dependent manner and selectively interacted with CRY2. By determining the X-ray crystal structure of CRY2 in complex with SHP656 and performing molecular dynamics simulations, we elucidated compound interaction mechanisms. SHP656 binding was compatible with the intrinsic CRY2 gatekeeper W417 "in" orientation and also a close "further in" conformation. Perturbation of W417 interaction with the lid loop resulted in a reduced effect of SHP656 on CRY2, supporting an important role of gatekeeper orientation in isoform selectivity. We also identified the R form of SHP656 (called SHP1703) as the active isomer. Treatment with SHP1703 effectively reduced GSC viability. Our results suggest a direct role of CRY2 in glioblastoma antitumorigenesis and provide a rationale for the selective modulation of CRY isoforms in the therapeutic treatment of glioblastoma and other circadian clock-related diseases.

Disruption of the circadian clock drives Apc loss of heterozygosity to accelerate colorectal cancer

An alarming rise in young onset colorectal cancer (CRC) has been reported; however, the underlying molecular mechanism remains undefined. Suspected risk factors of young onset CRC include environmental aspects, such as lifestyle and dietary factors, which are known to affect the circadian clock. We find that both genetic disruption and environmental disruption of the circadian clock accelerate Apc-driven CRC pathogenesis in vivo. Using an intestinal organoid model, we demonstrate that clock disruption promotes transformation by driving Apc loss of heterozygosity, which hyperactivates Wnt signaling. This up-regulates c-Myc, a known Wnt target, which drives heightened glycolytic metabolism. Using patient-derived organoids, we show that circadian rhythms are lost in human tumors. Last, we identify that variance between core clock and Wnt pathway genes significantly predicts the survival of patients with CRC. Overall, our findings demonstrate a previously unidentified mechanistic link between clock disruption and CRC, which has important implications for young onset cancer prevention.

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.

Magnetic fields and apoptosis: a possible mechanism

The potential therapeutic uses of electromagnetic fields (EMF), part of the nonionizing radiation spectrum, increase with time. Among them, those considering the potential antitumor effects exerted by the Magnetic Fields (MFs), part of the EMF entity, have gained more and more interest. A recent review on this subject reports the MFs' effect on apoptosis of tumor cells as one of the most important breakthroughs. Apoptosis is considered a key mechanism regulating the genetic stability of cells and as such is considered of fundamental importance in cancer initiation and development. According to an atomic/sub-atomic analysis, based on quantum physics, of the complexity of biological life and the role played by oxygen and its radicals in cancer biology, a possible biophysical mechanism is described. The mechanism considers the influence of MFs on apoptosis through an effect on electron spin that is able to increase reactive oxygen species (ROS) concentration. Impacting on the delicate balance between ROS production and ROS elimination in tumor cells is considered a promising cancer therapy, affecting different biological processes, such as apoptosis and metastasis. An analysis in the literature, which allows correlation between MFs exposure characteristics and their influence on apoptosis and ROS concentration, supports the validity of the mechanism.

Circadian rhythms and cancers: the intrinsic links and therapeutic potentials

The circadian rhythm is an evolutionarily conserved time-keeping system that comprises a wide variety of processes including sleep-wake cycles, eating-fasting cycles, and activity-rest cycles, coordinating the behavior and physiology of all organs for whole-body homeostasis. Acute disruption of circadian rhythm may lead to transient discomfort, whereas long-term irregular circadian rhythm will result in the dysfunction of the organism, therefore increasing the risks of numerous diseases especially cancers. Indeed, both epidemiological and experimental evidence has demonstrated the intrinsic link between dysregulated circadian rhythm and cancer. Accordingly, a rapidly increasing understanding of the molecular mechanisms of circadian rhythms is opening new options for cancer therapy, possibly by modulating the circadian clock. In this review, we first describe the general regulators of circadian rhythms and their functions on cancer. In addition, we provide insights into the mechanisms underlying how several types of disruption of the circadian rhythm (including sleep-wake, eating-fasting, and activity-rest) can drive cancer progression, which may expand our understanding of cancer development from the clock perspective. Moreover, we also summarize the potential applications of modulating circadian rhythms for cancer treatment, which may provide an optional therapeutic strategy for cancer patients.

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.

Structural and Chemical Biology Approaches Reveal Isoform-Selective Mechanisms of Ligand Interactions in Mammalian Cryptochromes

Cryptochromes (CRYs) are core components of the circadian feedback loop in mammals, which regulates circadian rhythmicity in a variety of physiological processes including sleep–wake cycles and metabolism. Dysfunction of CRY1 and CRY2 isoforms has been associated with a host of diseases, such as sleep phase disorder and metabolic diseases. Accumulating evidence for distinct roles of CRY1 and CRY2 has highlighted the need for CRY isoform-selective regulation; however, highly conserved sequences in CRY ligand-binding sites have hindered the design of isoform-selective compounds. Chemical biology approaches have been identifying small-molecule modulators of CRY proteins, which act in isoform-non-selective and also isoform-selective manners. In this review, we describe advances in our understanding of CRY isoform selectivity by comparing X-ray crystal structures of mammalian CRY isoforms in apo form and in complexes with compounds. We discuss how intrinsic conformational differences in identical residues of CRY1 and CRY2 contribute to unique interactions with different compound moieties for isoform selectivity.

Circadian effects on UV-induced damage and mutations

Skin cancer is the most diagnosed type of cancer in the United States, and while most of these malignancies are highly treatable, treatment costs still exceed $8 billion annually. Over the last 50 years, the annual incidence of skin cancer has steadily grown; therefore, understanding the environmental factors driving these types of cancer is a prominent research-focus. A causality between ultraviolet radiation (UVR) exposure and skin cancer is well-established, but exposure to UVR alone is not necessarily sufficient to induce carcinogenesis. The emerging field of circadian biology intersects strongly with the physiological systems of the mammalian body and introduces a unique opportunity for analyzing mechanisms of homeostatic disruption. The circadian clock refers to the approximate 24-hour cycle, in which protein levels of specific clock-controlled genes (CCGs) fluctuate based on the time of day. Though these CCGs are tissue specific, the skin has been observed to have a robust circadian clock that plays a role in its response to UVR exposure. This in-depth review will detail the mechanisms of the circadian clock and its role in cellular homeostasis. Next, the skin's response to UVR exposure and its induction of DNA damage and mutations will be covered - with an additional focus placed on how the circadian clock influences this response through nucleotide excision repair. Lastly, this review will discuss current models for studying UVR-induced skin lesions and perturbations of the circadian clock, as well as the impact of these factors on human health.