Identification of an estrogen-regulated circadian mechanism necessary for breast acinar morphogenesis

The Estrous Cycle Coordinates the Circadian Rhythm of Eating Behavior in Mice

The estrous cycle regulates rhythms of locomotor activity, body temperature, and circadian gene expression. In female mice, activity increases on the night of proestrus, when elevated estrogens cause ovulation. Exogenous estradiol regulates eating behavior rhythms in female mice fed a high-fat diet, but it is unknown whether endogenous estrogens regulate eating rhythms. In this study, we investigated whether diurnal and circadian eating behavior rhythms change systematically across the estrous cycle. We first studied diurnal eating behavior rhythms in female C57BL/6J mice in 12L:12D. Estrous cycle stages were determined by vaginal cytology while eating behavior and wheel revolutions were continuously measured. The mice had regular 4- to 5-day estrous cycles. Consistent with prior studies, the greatest number of wheel revolutions occurred on the night of proestrus into estrus when systemic levels of estrogens peak. The amplitude, or robustness, of the eating behavior rhythm also fluctuated with 4- to 5-day cycles and peaked primarily during proestrus or estrus. The phases of eating behavior rhythms fluctuated, but not at 4- or 5-day intervals, and phases did not correlate with estrous cycle stages. After ovariectomy, the eating behavior rhythm amplitude fluctuated at irregular intervals. In constant darkness, the amplitude of the circadian eating behavior rhythm peaked every 4 or 5 days and coincided with the circadian day that had the greatest number of wheel revolutions, a marker of proestrus. These data suggest that fluctuations of ovarian hormones across the estrous cycle temporally organize the robustness of circadian eating behavior rhythms so that it peaks during ovulation and sexual receptivity.

Circadian rhythms and breast cancer: from molecular level to therapeutic advancements

BACKGROUND AND OBJECTIVES

Circadian rhythms, the endogenous biological clocks that govern physiological processes, have emerged as pivotal regulators in the development and progression of breast cancer. This comprehensive review delves into the intricate interplay between circadian disruption and breast tumorigenesis from multifaceted perspectives, encompassing biological rhythms, circadian gene regulation, tumor microenvironment dynamics, and genetic polymorphisms.

METHODS AND RESULTS

Epidemiological evidence underscores the profound impact of external factors, such as night shift work, jet lag, dietary patterns, and exercise routines, on breast cancer risk and progression through the perturbation of circadian homeostasis. The review elucidates the distinct roles of key circadian genes, including CLOCK, BMAL1, PER, and CRY, in breast cancer biology, highlighting their therapeutic potential as molecular targets. Additionally, it investigates how circadian rhythm dysregulation shapes the tumor microenvironment, fostering epithelial-mesenchymal transition, chronic inflammation, and immunosuppression, thereby promoting tumor progression and metastasis. Furthermore, the review sheds light on the association between circadian gene polymorphisms and breast cancer susceptibility, paving the way for personalized risk assessment and tailored treatment strategies.

CONCLUSIONS

Importantly, it explores innovative therapeutic modalities that harness circadian rhythms, including chronotherapy, melatonin administration, and traditional Chinese medicine interventions. Overall, this comprehensive review emphasizes the critical role of circadian rhythms in the pathogenesis of breast cancer and highlights the promising prospects for the development of circadian rhythm-based interventions to enhance treatment efficacy and improve patient outcomes.

Redox and metabolic reprogramming in breast cancer and cancer-associated adipose tissue

Redox and metabolic processes are tightly coupled in both physiological and pathological conditions. In cancer, their integration occurs at multiple levels and is characterized by synchronized reprogramming both in the tumor tissue and its specific but heterogeneous microenvironment. In breast cancer, the principal microenvironment is the cancer-associated adipose tissue (CAAT). Understanding how the redox-metabolic reprogramming becomes coordinated in human breast cancer is imperative both for cancer prevention and for the establishment of new therapeutic approaches. This review aims to provide an overview of the current knowledge of the redox profiles and regulation of intermediary metabolism in breast cancer while considering the tumor and CAAT of breast cancer as a unique Warburg's pseudo-organ. As cancer is now recognized as a systemic metabolic disease, we have paid particular attention to the cell-specific redox-metabolic reprogramming and the roles of estrogen receptors and circadian rhythms, as well as their crosstalk in the development, growth, progression, and prognosis of breast cancer.

Effects of BXSMD on ESR1 and ESR2 expression in CSD female mice

ETHNIC PHARMACOLOGICAL RELEVANCE

Due to the rapid pace of modern society, chronic insomnia has become universal phenomenon. In China, Banxia Shumi Decoction (BXSMD) has been used in treating chronic insomnia for thousands of years, but its chemical composition and action mechanism are still unknown.

AIM OF THE STUDY

This study aims to explore the chemical composition of BXSMD and its effects on Estrogen receptor 1 (ESR1) and Estrogen receptor 2 (ESR2) in mice with chronic sleep deprivation (CSD).

MATERIALS AND METHODS

UHPLC-Q-Orbitrap-MS/MS was applied in determining the chemical composition of BXSMD. After 21-day sleep deprivation (SD) in platform water environment, CSD mice model was prepared. By conducting open field test, 24-h autonomic diurnal and nocturnal activity of mice in each group was detected. ELISA was employed to measure the contents of 5-HT, DA, NE, GABA, Glu, and MT. With RT-PCR, Western blot (WB), and immunohistochemistry (IHC), mRNA and protein expressions of ESR1 and ESR2 in the hypothalamus and hippocampus were tested.

RESULTS

BXSMD included ferulic acid, kaverol, daidzein, apigenin, berberine, adenosine, aesculin, vanillin, naringin, and glycine, which might constitute the material basis forthe improvement of chronic insomnia. With BXSMD, the total moving distance and the rest time in dark period of CSD mice were shortened, while its rest time in light period was increased. Besides, BXSMD enhanced the contents of 5-HT, GABA, and MT in CSD mice, and decreased the contents of Glu, NE, and DA. BXSMD elevated the mRNA of Esr1 and Esr2, and elevated the protein expressions of ESR1 and ESR2 in the hypothalamus and hippocampus of CSD mice.

CONCLUSIONS

BXSMD contains various chemical components for sleep-wake regulation, with the mechanism of stimulating estrogen signaling pathway by regulating the expressions of ESR1 and ESR2, ultimately realizing the regulation to sleep-wake disorder caused by CSD.

Effect of miR-34a on the expression of clock and clock-controlled genes in DLD1 and Lovo human cancer cells with different backgrounds with respect to p53 functionality and 17β-estradiol-mediated regulation

The small non-coding RNA miR-34a is a p53-regulated miRNA that acts as a tumour suppressor of colorectal cancer (CRC). Oncogenesis is also negatively influenced by deregulation of the circadian system in many types of tumours with various genetic backgrounds. As the clock gene per2 was recently recognized as one of the target genes of miR-34a, we focused on the miR-34a-mediated influence on the circadian oscillator in CRC cell lines DLD1 and LoVo, which differ in their p53 status. Previously, a sex-dependent association between the expression of per2 and that of miR-34a was demonstrated in CRC patients. Therefore, we also investigated the effect of 17β-estradiol (E2) on miR-34a oncostatic functions. miR-34a mimic caused a pronounced inhibition of per2 expression in both cell lines. Moreover, miR-34a mimic significantly inhibited bmal1 expression in LoVo and rev-erbα expression in DLD1 cells and induced clock gene expression in both cell lines. miR-34a mimic caused a pronounced decrease in sirt1 and cyclin D1 expression, which may be related to the inhibition of proliferation observed after mir-34a administration in DLD1 cells. E2 administration inhibited the migration and proliferation of DLD1 cells. E2 and miR-34a, when administered simultaneously, did not potentiate each other's effects. To conclude, miR-34a strongly influences the expression of components of the circadian oscillator without respect to p53 status and exerts its oncostatic effects via inhibition of sirt1 and cyclin D1 mRNA expression. E2 administration inhibits the growth of DLD1 cells; however, this effect seems to be independent of miR-34a-mediated action. With respect to the possible use of miR-34a in cancer treatment, clock genes can be considered as off-target genes, as changes in their expression induced by miR-34a treatment do not contribute to the oncostatic functions of miR-34a. Possible ambiguous oncogenic characteristics should be taken into consideration in future clinical studies focused on miR-34a.

The impact of biological clock and sex hormones on the risk of disease

Molecular clocks are responsible for defining 24-h cycles of behaviour and physiology that are called circadian rhythms. Several structures and tissues are responsible for generating these circadian rhythms and are named circadian clocks. The suprachiasmatic nucleus of the hypothalamus is believed to be the master circadian clock receiving light input via the optic nerve and aligning internal rhythms with environmental cues. Studies using both in vivo and in vitro methodologies have reported the relationship between the molecular clock and sex hormones. The circadian system is directly responsible for controlling the synthesis of sex hormones and this synthesis varies according to the time of day and phase of the estrous cycle. Sex hormones also directly interact with the circadian system to regulate circadian gene expression, adjust biological processes, and even adjust their own synthesis. Several diseases have been linked with alterations in either the sex hormone background or the molecular clock. So, in this chapter we aim to summarize the current understanding of the relationship between the circadian system and sex hormones and their combined role in the onset of several related diseases.

Krüppel-like factor 9 (KLF9) links hormone dysregulation and circadian disruption to breast cancer pathogenesis

BACKGROUND

Circadian disruption is an emerging driver of breast cancer (BCa), with epidemiological studies linking shift work and chronic jet lag to increased BCa risk. Indeed, several clock genes participate in the gating of mitotic entry, regulation of DNA damage response, and epithelial-to-mesenchymal transition, thus impacting BCa etiology. Dysregulated estrogen (17β-estradiol, E2) and glucocorticoid (GC) signaling prevalent in BCa may further contribute to clock desynchrony by directly regulating the expression and cycling dynamics of genes comprising the local breast oscillator. In this study, we investigated the tumor suppressor gene, Krüppel-like factor 9 (KLF9), as an important point of crosstalk between hormone signaling and the circadian molecular network, and further examine its functional role in BCa.

METHODS

Through meta-analysis of publicly available RNA- and ChIP-sequencing datasets from BCa tumor samples and cell lines, and gene expression analysis by RT-qPCR and enhancer- reporter assays, we elucidated the molecular mechanism behind the clock and hormone regulation of KLF9. Lentiviral knockdown and overexpression of KLF9 in three distinct breast epithelial cell lines (MCF10A, MCF7 and MDA-MB-231) was generated to demonstrate the role of KLF9 in orthogonal assays on breast epithelial survival, proliferation, apoptosis, and migration.

RESULTS

We determined that KLF9 is a direct GC receptor target in mammary epithelial cells, and that induction is likely mediated through coordinate transcriptional activation from multiple GC-responsive enhancers in the KLF9 locus. More interestingly, rhythmic expression of KLF9 in MCF10A cells was abolished in the highly aggressive MDA-MB-231 line. In turn, forced expression of KLF9 altered the baseline and GC/E2-responsive expression of several clock genes, indicating that KLF9 may function as a regulator of the core clock machinery. Characterization of the role of KLF9 using complementary cancer hallmark assays in the context of the hormone-circadian axis revealed that KLF9 plays a tumor-suppressive role in BCa regardless of molecular subtype. KLF9 potentiated the anti-tumorigenic effects of GC in E2 receptor + luminal MCF7 cells, while it restrained GC-enhanced oncogenicity in triple-negative MCF10A and MDA-MB-231 cells.

CONCLUSIONS

Taken together, our findings support that dysregulation of KLF9 expression and oscillation in BCa impinges on circadian network dynamics, thus ultimately affecting the BCa oncogenic landscape.

Obesity, cancer risk, and time-restricted eating

Obesity and the associated metabolic syndrome is considered a pandemic whose prevalence is steadily increasing in many countries worldwide. It is a complex, dynamic, and multifactorial disorder that presages the development of several metabolic, cardiovascular, and neurodegenerative diseases, and increases the risk of cancer. In patients with newly diagnosed cancer, obesity worsens prognosis, increasing the risk of recurrence and decreasing survival. The multiple negative effects of obesity on cancer outcomes are substantial, and of great clinical importance. Strategies for weight control have potential utility for both prevention efforts and enhancing cancer outcomes. Presently, time-restricted eating (TRE) is a popular dietary intervention that involves limiting the consumption of calories to a specific window of time without any proscribed caloric restriction or alteration in dietary composition. As such, TRE is a sustainable long-term behavioral modification, when compared to other dietary interventions, and has shown many health benefits in animals and humans. The preliminary data regarding the effects of time-restricted feeding on cancer development and growth in animal models are promising but studies in humans are lacking. Interestingly, several short-term randomized clinical trials of TRE have shown favorable effects to reduce cancer risk factors; however, long-term trials of TRE have yet to investigate reductions in cancer incidence or outcomes in the general population. Few studies have been conducted in cancer populations, but a number are underway to examine the effect of TRE on cancer biology and recurrence. Given the simplicity, feasibility, and favorable metabolic improvements elicited by TRE in obese men and women, TRE may be useful in obese cancer patients and cancer survivors; however, the clinical implementation of TRE in the cancer setting will require greater in-depth investigation.

Effect of 17β-estradiol on the daily pattern of ACE2, ADAM17, TMPRSS2 and estradiol receptor transcription in the lungs and colon of male rats

Covid-19 progression shows sex-dependent features. It is hypothesized that a better Covid-19 survival rate in females can be attributed to the presence of higher 17β-estradiol (E2) levels in women than in men. Virus SARS-CoV-2 is enabled to enter the cell with the use of angiotensin converting enzyme 2 (ACE2). The expression of several renin-angiotensin system components has been shown to exert a rhythmic pattern, and a role of the circadian system in their regulation has been implicated. Therefore, the aim of the study is to elucidate possible interference between E2 signalling and the circadian system in the regulation of the expression of ACE2 mRNA and functionally related molecules. E2 was administered at a dosage of 40 μg/kg/day for 7 days to male Wistar rats, and sampling of the lungs and colon was performed during a 24-h cycle. The daily pattern of expression of molecules facilitating SARS-CoV-2 entry into the cell, clock genes and E2 receptors was analysed. As a consequence of E2 administration, a rhythm in ACE2 and TMPRSS2 mRNA expression was observed in the lungs but not in the colon. ADAM17 mRNA expression showed a pronounced rhythmic pattern in both tissues that was not influenced by E2 treatment. ESR1 mRNA expression exerted a rhythmic pattern, which was diminished by E2 treatment. The influence of E2 administration on ESR2 and GPER1 mRNA expression was greater in the lungs than in the colon as a significant rhythm in ESR2 and GPER1 mRNA expression appeared only in the lungs after E2 treatment. E2 administration also increased the amplitude of bmal1 expression in the lungs, which implicates altered functioning of peripheral oscillators in response to E2 treatment. The daily pattern of components of the SARS-CoV-2 entrance pathway and their responsiveness to E2 should be considered in the timing of pharmacological therapy for Covid-19.

Estrogens and the circadian system

Circadian rhythms are ~24 h cycles of behavior and physiology that are generated by a network of molecular clocks located in nearly every tissue in the body. In mammals, the circadian system is organized hierarchically such that the suprachiasmatic nucleus (SCN) is the main circadian clock that receives light information from the eye and entrains to the light-dark cycle. The SCN then coordinates the timing of tissue clocks so internal rhythms are aligned with environmental cycles. Estrogens interact with the circadian system to regulate biological processes. At the molecular level, estrogens and circadian genes interact to regulate gene expression and cell biology. Estrogens also regulate circadian behavior across the estrous cycle. The timing of ovulation during the estrous cycle requires coincident estrogen and SCN signals. Studies using circadian gene reporter mice have also elucidated estrogen regulation of peripheral tissue clocks and metabolic rhythms. This review synthesizes current understanding of the interplay between estrogens and the circadian system, with a focus on female rodents, in regulating molecular, physiological, and behavioral processes.

Multi-omics analysis of the prognosis and therapeutic significance of circadian clock in ovarian cancer

Ovarian cancer (OV) is one of the most common female malignancies with high morbidity and mortality, but its mechanism is not fully understood. The circadian clock is involved in the regulation of the immune system and the tumor microenvironment, regulating biological processes and behaviors in multiple ways. Circadian rhythm disorders are considered a risk factor for tumorigenesis. Multi-omics analysis was performed to comprehensively illustrate the roles of circadian clock genes in OV, we found that most of circadian clock genes undergo epigenetic alterations in OV and are strongly correlated with overall and progression-free patient survival. These clock genes are mainly involved in the inhibition of Apoptosis pathway, Cell Cycle pathway and DNA Damage Response pathway, as well as the activation of RAS/MAPK pathway and RTK pathway. Drug sensitivity model indicate that the expression of core clock genes may associate with drug resistance. Further, immune infiltrates analysis shows that different mutant forms of core genes can not only suppress immune infiltration, but also affect clinical outcome of ovarian cancer patients. Overall, our results may provide novel insights for the potential selection of immunotherapeutic targets.

Circadian rhythm disorder: a potential inducer of vascular calcification?

Over the past decades, circadian rhythm has drawn a great attention in cardiovascular diseases. The expressions of rhythm genes fluctuate in accordance with the diurnal changes of vascular physiology, which highlights the pivotal effect of vascular clock. Recent researches show that the circadian clock can directly regulate the synthetic and secretory function of endothelial cells and phenotypic switch of vascular smooth muscle cells to adjust vascular relaxation and contraction. Importantly, dysfunction of vascular cells is involved in vascular calcification. Secretion of osteogenic cytokines and calcified vesicles in the vessel, osteogenic phenotype switch of vascular smooth muscle cells are all implicated in the calcification process. Moreover, circadian rhythm disorder can lead to abnormal hormone secretion, oxidative stress, inflammatory reaction, and autophagy, all of which should not be ignored in vascular calcification. Vascular senescence is another pathogenetic mechanism in vascular calcification. Accelerated vascular senescence may act as an important intermediate factor to promote vascular calcification in circadian rhythm disorders. In this review, we elaborate the potential effect of circadian rhythm disorder in vascular calcification and try to provide a new direction in the prevention of vascular calcification.

Emerging Cancer Epigenetic Mechanisms Regulated by All-Trans Retinoic Acid

All-trans retinoic acid (RA), which is the dietary bioactive derivative obtained from animal (retinol) and plant sources (beta-carotene), is a physiological lipid signal of both embryonic and postembryonic development. During pregnancy, either RA deficiency or an excessive RA intake is teratogenic. Too low or too high RA affects not only prenatal, but also postnatal, developmental processes such as myelopoiesis and mammary gland morphogenesis. In this review, we mostly focus on emerging RA-regulated epigenetic mechanisms involving RA receptor alpha (RARA) and Annexin A8 (ANXA8), which is a member of the Annexin family, as well as ANXA8 regulatory microRNAs (miRNAs). The first cancer showing ANXA8 upregulation was reported in acute promyelocytic leukemia (APL), which induces the differentiation arrest of promyelocytes due to defective RA signaling caused by RARA fusion genes as the PML-RARA gene. Over the years, ANXA8 has also been found to be upregulated in other cancers, even in the absence of RARA fusion genes. Mechanistic studies on human mammary cells and mammary glands of mice showed that ANXA8 upregulation is caused by genetic mutations affecting RARA functions. Although not all of the underlying mechanisms of ANXA8 upregulation have been elucidated, the interdependence of RA-RARA and ANXA8 seems to play a relevant role in some normal and tumorigenic settings.

MYC-Associated Factor MAX is a Regulator of the Circadian Clock

The circadian transcriptional network is based on a competition between transcriptional activator and repressor complexes regulating the rhythmic expression of clock-controlled genes. We show here that the MYC-associated factor X, MAX, plays a repressive role in this network and operates through a MYC-independent binding to E-box-containing regulatory regions within the promoters of circadian BMAL1 targets. We further show that this "clock" function of MAX is required for maintaining a proper circadian rhythm and that MAX and BMAL1 contribute to two temporally alternating transcriptional complexes on clock-regulated promoters. We also identified MAX network transcriptional repressor, MNT, as a fundamental partner of MAX-mediated circadian regulation. Collectively, our data indicate that MAX regulates clock gene expression and contributes to keeping the balance between positive and negative elements of the molecular clock machinery.

Restoring circadian synchrony in vitro facilitates physiological responses to environmental chemicals

BACKGROUND

The growing requirement of hazard and risk assessment of environmental chemicals and the efforts to minimize animal testing, increases the demand for innovative and predictive in vitro test systems in toxicology, reflecting the physiological conditions of human nature. Here, an elemental factor regulating a variety of physiological processes is the day-night rhythm. This circadian rhythm, describing a biological oscillation with a 24-h period is hardly acknowledged in toxicology and test method development. Whilst, in animals or humans the entire organism exhibits a rigorous cellular circadian synchrony, in conventional in vitro systems each cell follows its own rhythm, due to the absence of appropriate synchronizing signals.

OBJECTIVE

Here we investigated whether circadian synchronization of human cells in an in vitro system improves the cellular response and, thus, increases the sensitivity of the test system. Since the circadian regulation of metabolism is particularly well understood, and dioxin and dioxin-like compounds are of major concern for environmental health we focused on the ubiquitous drug metabolizing detoxification system mediated by the aryl hydrocarbon receptor (AHR).

METHODS

To this end, we applied various prototypical AHR activators onto different human cell lines under non-synchronized or circadian synchronized conditions and determined the dose response on representative endogenous target genes.

RESULTS

Remarkably, the cellular response dynamic upon chemical treatment was substantially enhanced in circadian synchronized cells and followed a rhythmic expression pattern. This broader dynamic range was associated with a strikingly higher induction of AHR target genes and the corresponding enzymatic activity, thereby rather mimicking the in vivo situation.

CONCLUSION

Our findings indicate that a synchronized circadian rhythm in a cell culture based test system can improve the physiological relevance of an appropriate in vitro method by reflecting the biological in vivo situation more closely. Accordingly, it is a promising tool to facilitate the wide acceptance of in vitro methods in the field of regulatory toxicology and to further optimize the toxicological assessment of environmental chemicals.

High-Fat Diet Alters Circadian Rhythms in Mammary Glands of Pubertal Mice

Childhood obesity in girls is associated with early puberty and menarche. Breast tissue exhibits circadian rhythms. These rhythms may be altered by environmental factors. We hypothesized that a high-fat diet (HFD) disrupts circadian rhythms in pubertal mammary glands. Weanling female C57BL/6 mice were fed the standard AIN93G diet or a HFD (providing 16% or 45% of energy from soybean oil) for 3 weeks. Mammary glands were harvested from 6-week-old mice every 4 h on Zeitgeber time over a 48-h period; rhythmic expressions of circadian genes and genes encoding estrogen receptor and progesterone receptor were analyzed by using the Cosinor model. HFD, compared to AIN93G diet, altered diurnal oscillations of circadian genes in pubertal mammary glands. These included changes in amplitude of Per2, Cry1 (reduced), Clock, Rev-erbα, and Per1 (elevated), a delay in acrophase (the hour at which the rhythm peaks) of Bmal1 by 2.2 h, and changes in mesor (the mean of the rhythm from peak to trough) of Bmal1, Per2, Cry1 (reduced), Rev-rebα, and Per1 (elevated). Furthermore, HFD altered diurnal expression of estrogen receptor and progesterone receptor at both mRNA and protein levels. These findings indicate that HFD alters circadian regulation in pubertal mammary glands, which may contribute to the disturbance of hormonal homeostasis and lead to early development and growth of mammary glands in pubertal mice.

Circadian oscillations persist in low malignancy breast cancer cells

Epidemiological studies have shown that humans with altered circadian rhythms have higher cancer incidence, with breast cancer being one of the most cited examples. To uncover how circadian disruptions may be correlated with breast cancer and its development, prior studies have assessed the expression of BMAL1 and PER2 core clock genes via RT-qPCR and western blot analyses. These and our own low-resolution data show that BMAL1 and PER2 expression are suppressed and arrhythmic. We hypothesized that oscillations persist in breast cancer cells, but due to limitations of protocols utilized, cannot be observed. This is especially true where dynamic changes may be subtle. In the present work, we generated luciferase reporter cell lines representing high- and low-grade breast cancers to assess circadian rhythms. We tracked signals for BMAL1 and PER2 to determine whether and to what extent oscillations exist and provide initial correlations of circadian rhythm alterations with breast cancer aggression. In contrast to previous studies, where no oscillations were apparent in any breast cancer cell line, our luminometry data reveal that circadian oscillations of BMAL1 and PER2 in fact exist in the low-grade, luminal A MCF7 cells but are not present in high-grade, basal MDA-MB-231 cells. To our knowledge, this is the first evidence of core circadian clock oscillations in breast cancer cells. This work also suggests that circadian rhythms are further disrupted in more aggressive/high tumor grades of breast cancer, and that use of real time luminometry to study additional representatives of breast and other cancer subtypes is merited.

3D Mammary Epithelial Cell Models: A Goldmine of DCIS Biomarkers and Morphogenetic Mechanisms

Breast ductal carcinoma in situ (DCIS) has been typically recognized by pathologists on the basis of aberrant mammary duct morphology. Thus, there are increasing efforts to detect DCIS biomarkers and druggable targets. In this study we focused on the molecular mechanism involving Annexin A8 (ANXA8), a Ca²⁺ and phospholipid binding protein, which is regulated by all-trans Retinoic Acid (RA), and it is highly expressed in breast DCIS tissue samples relative to atypical ductal hyperplasia, and normal breast tissue. Using a panel of human mammary epithelial HME1 cell lines that share a common protein signature, and develop in vitro three dimensional (3D) “DCIS-like” amorphous structures, we identified by bioinformatics analysis protein-miRNA pairs, potentially involved in mammary morphogenetic mechanisms, including the ANXA8 mechanism. HME1 cells with genetic mutations hampering the physiological RA regulation of the RA receptor alpha (RARA) transcriptional function, but retain the RARA function controlling the PI3KCA-AKT signaling, develop 3D “DCIS-like” amorphous structures with upregulated ANXA8. Consistently, ectopic ANXA8 expression, by affecting the RARA transcriptional function, induced HME1 DCIS-like amorphous acini expressing phosphorylated AKT (P-AKT). Apparently, a RA-RARA-ANXA8 feedback loop fosters a vicious circle of aberrant morphogenesis. Interestingly, a few miRNAs regulated by RA are predicted to target ANXA8 mRNA. These miRNAs are candidate components of the RA-RARA-ANXA8 mechanism, and their deregulation might induce DCIS initiation.

An Overview of the Polymorphisms of Circadian Genes Associated With Endocrine Cancer

A major consequence of the world industrialized lifestyle is the increasing period of unnatural light in environments during the day and artificial lighting at night. This major change disrupts endogenous homeostasis with external circadian cues, which has been associated to higher risk of diseases affecting human health, mainly cancer among others. Circadian disruption promotes tumor development and accelerate its fast progression. The dysregulation mechanisms of circadian genes is greatly affected by the genetic variability of these genes. To date, several core circadian genes, also called circadian clock genes, have been identified, comprising the following: ARNTL, CLOCK, CRY1, CRY2, CSNK1E, NPAS2, NR1D1, NR1D2, PER1, PER2, PER3, RORA, and TIMELESS. The polymorphic variants of these circadian genes might contribute to an individual's risk to cancer. In this short review, we focused on clock circadian clock-related genes, major contributors of the susceptibility to endocrine-dependent cancers through affecting circadian clock, most likely affecting hormonal regulation. We examined polymorphisms affecting breast, prostate and ovarian carcinogenesis, in addition to pancreatic and thyroid cancer. Further study of the genetic composition in circadian clock-controlled tumors will be of great importance by establishing the foundation to discover novel genetic biomarkers for cancer prevention, prognosis and target therapies.

Rapid Communication: Period2 gene silencing increases the synthesis of αs-casein protein in bovine mammary epithelial cells

(), a core clock gene, encodes a circadian rhythm protein which has been shown to control mammary metabolism in rodents. Whether regulates milk component synthesis such as α-casein protein in bovine mammary cells is unknown. Thus, we used gene silencing technology to determine if silencing could affect α-casein synthesis and cell growth in cultured primary bovine mammary epithelial cells (BMEC). The BMEC were established by enzymatic digestion of mammary tissue from mid-lactation cows. A transient-transfection technique was used to insert a small interfering RNA (siRNA) oligonucleotide specific for to inhibit transcription. Control and siRNA-transfected cells were cultured for 48 h. qRT-PCR and ELISA analysis showed that silencing enhanced the synthesis of 2 kinds of α-casein ( < 0.05) through upregulating the mRNA level of and ( < 0.01). Furthermore, the 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) results demonstrated that cell proliferation was not affected ( > 0.05). These data led us to hypothesize that PER2 protein may potentially play an important role in the control of milk protein synthesis and, hence, represents a target that can be used to regulate protein synthesis rate during lactation.

Altered Circadian Rhythms and Breast Cancer: From the Human to the Molecular Level

Circadian clocks are fundamental, time-tracking systems that allow organisms to adapt to the appropriate time of day and drive many physiological and cellular processes. Altered circadian rhythms can result from night-shift work, chronic jet lag, exposure to bright lights at night, or other conditioning, and have been shown to lead to increased likelihood of cancer, metabolic and cardiovascular diseases, and immune dysregulation. In cases of cancer, worse patient prognoses and drug resistance during treatment have also been observed. Breast, colon, prostate, lung, and ovarian cancers and hepatocellular carcinoma have all been linked in one way or another with altered circadian rhythms. Critical elements at the molecular level of the circadian system have been associated with cancer, but there have been fairly few studies in this regard. In this mini-review, we specifically focus on the role of altered circadian rhythms in breast cancer, providing an overview of studies performed at the epidemiological level through assessments made in animal and cellular models of the disease. We also address the disparities present among studies that take into account the rhythmicity of core clock and other proteins, and those which do not, and offer insights to the use of small molecules for studying the connections between circadian rhythms and cancer. This article will provide the reader with a concise, but thorough account of the research landscape as it pertains to altered circadian rhythms and breast cancer.

The sweet tooth of the circadian clock

The endogenous circadian clock is a key regulator of daily metabolic processes. On the other hand, circadian clocks in a broad range of tissues can be tuned by extrinsic and intrinsic metabolic cues. The bidirectional interaction between circadian clocks and metabolism involves both transcriptional and post-translational mechanisms. Nuclear receptors exemplify the transcriptional programs that couple molecular clocks to metabolism. The post-translational modifications of the core clock machinery are known to play a key role in metabolic entrainment of circadian clocks. O-linked N-acetylglucosamine modification (O-GlcNAcylation) of intracellular proteins is a key mediator of metabolic response to nutrient availability. This review highlights our current understanding of the role of protein O-GlcNAcylation in mediating metabolic input and output of the circadian clock.

Circadian clocks and breast cancer

Circadian clocks respond to environmental time cues to coordinate 24-hour oscillations in almost every tissue of the body. In the breast, circadian clocks regulate the rhythmic expression of numerous genes. Disrupted expression of circadian genes can alter breast biology and may promote cancer. Here we overview circadian mechanisms, and the connection between the molecular clock and breast biology. We describe how disruption of circadian genes contributes to cancer via multiple mechanisms, and link this to increased tumour risk in women who work irregular shift patterns. Understanding the influence of circadian rhythms on breast cancer could lead to more efficacious therapies, reformed public health policy and improved patient outcome.

Harnessing 3D models of mammary epithelial morphogenesis: An off the beaten path approach to identify candidate biomarkers of early stage breast cancer

Regardless of the etiological factor, an aberrant morphology is the common hallmark of ductal carcinoma in situ (DCIS), which is a highly heterogeneous disease. To test if critical core morphogenetic mechanisms are compromised by different mutations, we performed proteomics analysis of five mammary epithelial HME1 mutant lines that develop a DCIS-like morphology in three dimensional (3D) culture. Here we show first, that all HME1 mutant lines share a common protein signature highlighting an inverse deregulation of two annexins, ANXA2 and ANXA8. Either ANXA2 downregulation or ANXA8 upregulation in the HME1 cell context are per se sufficient to confer a 3D DCIS-like morphology. Seemingly, different mutations impinged on a common mechanism that differentially regulates the two annexins. Second, we show that ANXA8 expression is significantly higher in DCIS tissue samples versus normal breast tissue and atypical ductal hyperplasia (ADH). Apparently, ANXA8 expression is significantly more upregulated in ER-negative versus ER-positive cases, and significantly correlates with tumor stage, grade and positive lymph node. Based on our study, 3D mammary morphogenesis models can be an alternate/complementary strategy for unraveling new DCIS mechanisms and biomarkers.

Circadian Genes in Breast Cancer

Exploring the putative impact of circadian rhythms is a relatively novel approach to illuminating hormone-related female breast cancer etiology and prognosis. One of several proposed mechanisms underlying breast cancer risk among individuals exposed to light at night involves circadian gene alterations. Although in vitro and animal studies indicate a key role of circadian genes in breast tumor suppression, there is a paucity of data on the role of circadian genes in human breast cancer. This review summarizes recent findings of circadian gene expression and DNA methylation profile from human breast cancer studies in relation to hormonal status, clinicopathological features of tumors, and exposure to night shift work. The major findings from human studies indicate that expression of circadian genes is deregulated in breast cancer. Breast cancer etiology and prognosis-associated PERs, CRYs, CLOCK downregulation, and TIMELESS upregulation may be related to relevant gene methylation in tumor tissue. Alterations and desynchronization of molecular clock machinery found on genetic and epigenetic level were observed in more aggressive breast cancer tumors and those lacking estrogen receptors.

Recent advances on the circadian gene PER2 and metabolic rhythm of lactation of mammary gland

Due to regulation by circadian rhythm, the lactation of the mammary gland has rhythmicity. As one of prominent members of period protein family which regulates biological rhythms, PER2 plays an important role in developing the milk duct and maintaining the polarity and the morphology of the mammary epithelium; at the same time, it is also closely related with the metabolism of milk protein and milk fat. This paper summarized recent researches on PER2 gene and related researches on mammary gland development and metabolism to provide some information for the studies of the theory and technology on physiological functions of the mammary gland and milk quality control.

Induction of the CLOCK gene by E2-ERα signaling promotes the proliferation of breast cancer cells

Growing genetic and epidemiological evidence suggests a direct connection between the disruption of circadian rhythm and breast cancer. Moreover, the expression of several molecular components constituting the circadian clock machinery has been found to be modulated by estrogen-estrogen receptor α (E2-ERα) signaling in ERα-positive breast cancer cells. In this study, we investigated the regulation of CLOCK expression by ERα and its roles in cell proliferation. Immunohistochemical analysis of human breast tumor samples revealed high expression of CLOCK in ERα-positive breast tumor samples. Subsequent experiments using ERα-positive human breast cancer cell lines showed that both protein and mRNA levels of CLOCK were up-regulated by E2 and ERα. In these cells, E2 promoted the binding of ERα to the EREs (estrogen-response elements) of CLOCK promoter, thereby up-regulating the transcription of CLOCK. Knockdown of CLOCK attenuated cell proliferation in ERα-positive breast cancer cells. Taken together, these results demonstrated that CLOCK could be an important gene that mediates cell proliferation in breast cancer cells.

The role of circadian rhythm in breast cancer

The circadian rhythm is an endogenous time keeping system shared by most organisms. The circadian clock is comprised of both peripheral oscillators in most organ tissues of the body and a central pacemaker located in the suprachiasmatic nucleus (SCN) of the central nervous system. The circadian rhythm is crucial in maintaining the normal physiology of the organism including, but not limited to, cell proliferation, cell cycle progression, and cellular metabolism; whereas disruption of the circadian rhythm is closely related to multi-tumorigenesis. In the past several years, studies from different fields have revealed that the genetic or functional disruption of the molecular circadian rhythm has been found in various cancers, such as breast, prostate, and ovarian. In this review, we will investigate and present an overview of the current research on the influence of circadian rhythm regulating proteins on breast cancer.