Potential Mechanisms by which Glucocorticoids Induce Breast Carcinogenesis through Nrf2 Inhibition

Implication of Let7b/AhR/ARNT/HMGB1/RAGE cascade in neuroplasticity disturbances induced by glucocorticoids and the promising reversible effect of 3,3 diindolymethane: Bidirectional crosstalk of Aryl hydrocarbon receptors

Prolonged exposure to glucocorticoids (GC) disrupts neuronal architecture, hinders neuroplasticity, and triggers neuroinflammation. However, the precise underlying mechanisms have not been studied yet. The current study aimed to investigate the mechanisms of GC-induced neuroinflammatory effects by stimulating the miRNA let7b, aryl hydrocarbon receptor (AhR)/ARNT, HMGB1/RAGE, and other downstream targets. Rats were divided into 4 groups; control, GC (20 mg/kg, S.C.), 3,3'-diindolylmethane (DIM) 50 mg/kg/day, and donepezil (DNZ) 4 mg/kg/day for 21 days. Behavioral tests and histopathological investigations of cerebral cortex were done. Let7b, AhR, ARNT, and cytochrome A1A were estimated using qRT-PCR. HMGB1, RAGE, NQO1and NRF2 were estimated using ELISA, whereas GFAP and TNF-α by immunohistochemical analysis. Keap1 was estimated using Western technique. GSH and TBARS were assessed by colorimetric assay. In the current study, GC elevates the gene expressions of let7b, AhR, ARNT, and cytochrome A1A, along with the protein contents of HMGB1, RAGE, NQO1and NRF2. In addition, GC showed increased GFAP, TNF-α, and TBARS, together with decreased Keap1 and GSH. On the other side, DIM and DNZ reversed all the above-mentioned findings. Collectively, the study documents for the first time the effect of GC in upregulating let7b and activating the AhR/ARNT loop which subsequently stimulates RAGE/HMGB1 and NRF2/Keap1 cascade leading to stimulating further inflammatory and oxidative signaling pathways. Certainly, these effects are responsible for the behavioral fluctuations, the brain's histological disruption, altered neuroplasticity, and neuroinflammation induced by GC. Moreover, DIM conquers GC-induced neuroinflammation due to its characteristic role in modulating AhR and its downstream targets.

Identification of common core genes and pathways in childhood sepsis and cancer by bioinformatics analysis

INTRODUCTION

Sepsis and cancer are both leading causes of death worldwide, and they share several pathophysiological characteristics. Some studies have suggested a possible association between sepsis and cancer; however, few have investigated the core genes involved in both diseases.

METHODS

Core genes common to both sepsis and cancer were identified using pediatric sepsis datasets (GEO: GSE26378, GSE4607, GSE8121 and GSE13904) and cancer databases (TCGA: BRCA, COADREAD, ESCA, KIRC, LIHC, LUAD, STAD). Gene Ontology (GO) and Reactome enrichment analyses, along with a protein-protein interaction (PPI) network analysis, were performed. Pharmacophore screening was applied to predict the targets of oxymatrine and ulinastatin, and potential target genes shared by both cancer and sepsis were identified. Survival analysis was performed. The association between the target genes and tumor size and number of positive lymph nodes was investigated by Pearson correlation analysis. The association between the target genes and tumor stage was investigated by Fisher's exact test. Molecular docking analysis was performed to evaluate the affinity of the candidate drugs for their targets.

RESULTS

A total of 641 common genes were identified. GO enrichment analysis showed that common genes were enriched in neutrophil degranulation, inflammatory response and innate immune response. Reactome enrichment analysis showed that common genes were enriched in neutrophil degranulation, interleukin-4 and interleukin-13 signaling, transcriptional regulation of granulopoiesis and interleukin-10 signaling. The PPI network showed that the top 10 core genes were TLR4, IL1B, IL10, ITGAM, TLR2, PTPRC, CDK1, FOS, MMP9 and ITGB2. The survival analysis showed that the high expression of BCAT1, CSAD, G6PD, GM2A, MMP9, PYGL and TOP2A was associated with poorer prognosis in several cancers. Molecular docking showed that oxymatrine and ulinastatin can bind to protein targets with highly stable binding.

CONCLUSIONS

We identified genes with common effects on both childhood sepsis and cancer, which provides new insights into the association between sepsis and cancer. In addition, two drugs with potential clinical application value were identified. Further studies are required to validate the role of these common core genes in sepsis and cancer and to evaluate the potential utility of these drugs.

Effects of Hormonal Replacement Therapy and Mindfulness-Based Stress Reduction on Climacteric Symptoms Following Risk-Reducing Salpingo-Oophorectomy

Breast Cancer Associated Susceptibility Proteins Type 1/2 (BRCA1/2) promote cellular functioning by modulating NRF2-mediated antioxidant signaling. Redox failure in women with BRCA1/2 insufficiency increases the risk for breast/ovarian/uterine cancers. Risk-reducing salpingo-oophorectomy (RRSO) is a prophylactic surgery of the reproductive organs, which is frequently conducted by the age of 40 to lower the occurrence of cancer in women with BRCA1/2 mutations. However, abrupt estrogen decline following RRSO causes ovarian failure, which implicates various cellular physiological processes, resulting in the increased release of free radicals and subsequent severe onset of menopausal symptoms. Comfort measures (e.g., hormonal replacement therapy (HRT) and mindfulness-based stress reduction (MBSR)) may improve chronological menopause-related quality of life, but their specific effects are not clear in women with gene mutations. Aiming to fill the gap, this study used path analysis to examine the effects of HRT and MBSR on menopausal symptoms among RRSO patients (N = 199, mean age = 50.5 ± 6.7 years). HRT directly alleviated the levels of urogenital symptoms (β = -0.195, p = 0.005), which mediated its indirect significant effects on the somatic-vegetative and psychological symptoms of menopause (β = -0.046, -0.067; both p values = 0.004, respectively), especially in BRCA2 carriers and in women who were currently physically active, premenopausal at the time of RRSO, had a high BMI, and had no history of breast cancer. It increased the severity of urogenital symptoms in women with a history of cancer. MBSR, on the other hand, was associated with indirect increases in the intensity of the somatic-vegetative and psychological symptoms of menopause (β = 0.108, 0.029; p = 0.003, 0.033, respectively). It exerted positive direct effects on different menopausal symptoms in multigroup analysis. The results suggest that young women undergoing recent RRSO may benefit from HRT at an individual level, while their need for extensive measures to optimize their psychological wellbeing is ongoing. The adverse effects of MBSR, which are captured in the present study, imply that MBSR may interfere with redox sensitivity associated with estradiol fluctuations in BRCA1/2 carriers. Investigations are needed to test this hypothesis and elaborate on the underlying mechanisms in these women.

A Review of the Potential of Nuclear Factor [Erythroid-Derived 2]-like 2 Activation in Autoimmune Diseases

An autoimmune disease is the consequence of the immune system attacking healthy cells, tissues, and organs by mistake instead of protecting them. Inflammation and oxidative stress (OS) are well-recognized processes occurring in association with acute or chronic impairment of cell homeostasis. The transcription factor Nrf2 (nuclear factor [erythroid-derived 2]-like 2) is of major importance as the defense instrument against OS and alters anti-inflammatory activities related to different pathological states. Researchers have described Nrf2 as a significant regulator of innate immunity. Growing indications suggest that the Nrf2 signaling pathway is deregulated in numerous diseases, including autoimmune disorders. The advantageous outcome of the pharmacological activation of Nrf2 is an essential part of Nrf2-based chemoprevention and intervention in other chronic illnesses, such as neurodegeneration, cardiovascular disease, autoimmune diseases, and chronic kidney and liver disease. Nevertheless, a growing number of investigations have indicated that Nrf2 is already elevated in specific cancer and disease steps, suggesting that the pharmacological agents developed to mitigate the potentially destructive or transformative results associated with the protracted activation of Nrf2 should also be evaluated. The activators of Nrf2 have revealed an improvement in the progress of OS-associated diseases, resulting in immunoregulatory and anti-inflammatory activities; by contrast, the depletion of Nrf2 worsens disease progression. These data strengthen the growing attention to the biological properties of Nrf2 and its possible healing power on diseases. The evidence supporting a correlation between Nrf2 signaling and the most common autoimmune diseases is reviewed here. We focus on the aspects related to the possible effect of Nrf2 activation in ameliorating pathologic conditions based on the role of this regulator of antioxidant genes in the control of inflammation and OS, which are processes related to the progression of autoimmune diseases. Finally, the possibility of Nrf2 activation as a new drug development strategy to target pathogenesis is proposed.

Melatonin, BAG-1 and cortisol circadian interactions in tumor pathogenesis and patterned immune responses

A dysregulated circadian rhythm is significantly associated with cancer risk, as is aging. Both aging and circadian dysregulation show suppressed pineal melatonin, which is indicated in many studies to be linked to cancer risk and progression. Another independently investigated aspect of the circadian rhythm is the cortisol awakening response (CAR), which is linked to stress-associated hypothalamus-pituitary-adrenal (HPA) axis activation. CAR and HPA axis activity are primarily mediated via activation of the glucocorticoid receptor (GR), which drives patterned gene expression via binding to the promotors of glucocorticoid response element (GRE)-expressing genes. Recent data shows that the GR can be prevented from nuclear translocation by the B cell lymphoma-2 (Bcl-2)-associated athanogene 1 (BAG-1), which translocates the GR to mitochondria, where it can have diverse effects. Melatonin also suppresses GR nuclear translocation by maintaining the GR in a complex with heat shock protein 90 (Hsp90). Melatonin, directly and/or epigenetically, can upregulate BAG-1, suggesting that the dramatic 10-fold decrease in pineal melatonin from adolescence to the ninth decade of life will attenuate the capacity of night-time melatonin to modulate the effects of the early morning CAR. The interactions of pineal melatonin/BAG-1/Hsp90 with the CAR are proposed to underpin how aging and circadian dysregulation are associated with cancer risk. This may be mediated via differential effects of melatonin/BAG-1/Hsp90/GR in different cells of microenvironments across the body, from which tumors emerge. This provides a model of cancer pathogenesis that better integrates previously disparate bodies of data, including how immune cells are regulated by cancer cells in the tumor microenvironment, at least partly via the cancer cell regulation of the tryptophan-melatonin pathway. This has a number of future research and treatment implications.

Chronic stress induces pulmonary epithelial cells to produce acetylcholine that remodels lung pre-metastatic niche of breast cancer by enhancing NETosis

BACKGROUND

Chronic stress promotes most hallmarks of cancer through impacting the malignant tissues, their microenvironment, immunity, lymphatic flow, etc. Existing studies mainly focused on the roles of stress-induced activation of systemic sympathetic nervous system and other stress-induced hormones, the organ specificity of chronic stress in shaping the pre-metastatic niche remains largely unknown. This study investigated the role of chronic stress in remodeling lung pre-metastatic niche of breast cancer.

METHODS

Breast cancer mouse models with chronic stress were constructed by restraint or unpredictable stress. Expressions of tyrosine hydroxylase, vesicular acetylcholine transporter (VAChT), EpCAM and NETosis were examined by immunofluorescence and confocal microscopy. mRNA and protein levels of choline acetyltransferase (ChAT), VAChT, and peptidylarginine deiminase 4 were detected by qRT-PCR and Western blotting, respectively. Immune cell subsets were analyzed by flow cytometry. Acetylcholine (ACh) and chemokines were detected by ELISA and multi chemokine array, respectively. ChAT in lung tissues from patients was examined by immunohistochemistry.

RESULTS

Breast cancer-bearing mice suffered chronic stress metastasized earlier and showed more severe lung metastasis than did mice in control group. VAChT, ChAT and ChAT+ epithelial cells were increased significantly in lung of model mice undergone chronic stress. ACh and chemokines especially CXCL2 in lung culture supernatants from model mice with chronic stress were profoundly increased. Chronic stress remodeled lung immune cell subsets with striking increase of neutrophils, enhanced NETosis in lung and promoted NETotic neutrophils to capture cancer cells. ACh treatment resulted in enhanced NETosis of neutrophils. The expression of ChAT in lung tissues from breast cancer patients with lung metastasis was significantly higher than that in patients with non-tumor pulmonary diseases.

CONCLUSIONS

Chronic stress promotes production of CXCL2 that recruits neutrophils into lung, and induces pulmonary epithelial cells to produce ACh that enhances NETosis of neutrophils. Our findings demonstrate for the first time that chronic stress induced epithelial cell derived ACh plays a key role in remodeling lung pre-metastatic niche of breast cancer.

Nrf2 signaling pathway: current status and potential therapeutic targetable role in human cancers

Cancer is a borderless global health challenge that continues to threaten human health. Studies have found that oxidative stress (OS) is often associated with the etiology of many diseases, especially the aging process and cancer. Involved in the OS reaction as a key transcription factor, Nrf2 is a pivotal regulator of cellular redox state and detoxification. Nrf2 can prevent oxidative damage by regulating gene expression with antioxidant response elements (ARE) to promote the antioxidant response process. OS is generated with an imbalance in the redox state and promotes the accumulation of mutations and genome instability, thus associated with the establishment and development of different cancers. Nrf2 activation regulates a plethora of processes inducing cellular proliferation, differentiation and death, and is strongly associated with OS-mediated cancer. What's more, Nrf2 activation is also involved in anti-inflammatory effects and metabolic disorders, neurodegenerative diseases, and multidrug resistance. Nrf2 is highly expressed in multiple human body parts of digestive system, respiratory system, reproductive system and nervous system. In oncology research, Nrf2 has emerged as a promising therapeutic target. Therefore, certain natural compounds and drugs can exert anti-cancer effects through the Nrf2 signaling pathway, and blocking the Nrf2 signaling pathway can reduce some types of tumor recurrence rates and increase sensitivity to chemotherapy. However, Nrf2's dual role and controversial impact in cancer are inevitable consideration factors when treating Nrf2 as a therapeutic target. In this review, we summarized the current state of biological characteristics of Nrf2 and its dual role and development mechanism in different tumor cells, discussed Keap1/Nrf2/ARE signaling pathway and its downstream genes, elaborated the expression of related signaling pathways such as AMPK/mTOR and NF-κB. Besides, the main mechanism of Nrf2 as a cancer therapeutic target and the therapeutic strategies using Nrf2 inhibitors or activators, as well as the possible positive and negative effects of Nrf2 activation were also reviewed. It can be concluded that Nrf2 is related to OS and serves as an important factor in cancer formation and development, thus provides a basis for targeted therapy in human cancers.

The Multi-Faceted Consequences of NRF2 Activation throughout Carcinogenesis

The oxidative balance of a cell is maintained by the Kelch-like ECH-associated protein 1 (KEAP1)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway. This cytoprotective pathway detoxifies reactive oxygen species and xenobiotics. The role of the KEAP1/NRF2 pathway as pro-tumorigenic or anti-tumorigenic throughout stages of carcinogenesis (including initiation, promotion, progression, and metastasis) is complex. This mini review focuses on key studies describing how the KEAP1/NRF2 pathway affects cancer at different phases. The data compiled suggest that the roles of KEAP1/NRF2 in cancer are highly dependent on context; specifically, the model used (carcinogen-induced vs genetic), the tumor type, and the stage of cancer. Moreover, emerging data suggests that KEAP1/NRF2 is also important for regulating the tumor microenvironment and how its effects are amplified either by epigenetics or in response to co-occurring mutations. Further elucidation of the complexity of this pathway is needed in order to develop novel pharmacological tools and drugs to improve patient outcomes.

Survival Mechanisms of Metastatic Melanoma Cells: The Link between Glucocorticoids and the Nrf2-Dependent Antioxidant Defense System

Circulating glucocorticoids increase during stress. Chronic stress, characterized by a sustained increase in serum levels of cortisol, has been associated in different cases with an increased risk of cancer and a worse prognosis. Glucocorticoids can promote gluconeogenesis, mobilization of amino acids, fat breakdown, and impair the body's immune response. Therefore, conditions that may favor cancer growth and the acquisition of radio- and chemo-resistance. We found that glucocorticoid receptor knockdown diminishes the antioxidant protection of murine B16-F10 (highly metastatic) melanoma cells, thus leading to a drastic decrease in their survival during interaction with the vascular endothelium. The BRAF^V600E mutation is the most commonly observed in melanoma patients. Recent studies revealed that VMF/PLX40-32 (vemurafenib, a selective inhibitor of mutant BRAF^V600E) increases mitochondrial respiration and reactive oxygen species (ROS) production in BRAF^V600E human melanoma cell lines. Early-stage cancer cells lacking Nrf2 generate high ROS levels and exhibit a senescence-like growth arrest. Thus, it is likely that a glucocorticoid receptor antagonist (RU486) could increase the efficacy of BRAF-related therapy in BRAF^V600E-mutated melanoma. In fact, during early progression of skin melanoma metastases, RU486 and VMF induced metastases regression. However, treatment at an advanced stage of growth found resistance to RU486 and VMF. This resistance was mechanistically linked to overexpression of proteins of the Bcl-2 family (Bcl-xL and Mcl-1 in different human models). Moreover, melanoma resistance was decreased if AKT and NF-κB signaling pathways were blocked. These findings highlight mechanisms by which metastatic melanoma cells adapt to survive and could help in the development of most effective therapeutic strategies.

The Role of Glucocorticoids in Breast Cancer Therapy

Glucocorticoids (GCs) are anti-inflammatory and immunosuppressive steroid molecules secreted by the adrenal gland and regulated by the hypothalamic-pituitary-adrenal (HPA) axis. GCs present a circadian release pattern under normal conditions; they increase their release under stress conditions. Their mechanism of action can be via the receptor-independent or receptor-dependent pathway. The receptor-dependent pathway translocates to the nucleus, where the ligand-receptor complex binds to specific sequences in the DNA to modulate the transcription of specific genes. The glucocorticoid receptor (GR) and its endogenous ligand cortisol (CORT) in humans, and corticosterone in rodents or its exogenous ligand, dexamethasone (DEX), have been extensively studied in breast cancer. Its clinical utility in oncology has mainly focused on using DEX as an antiemetic to prevent chemotherapy-induced nausea and vomiting. In this review, we compile the results reported in the literature in recent years, highlighting current trends and unresolved controversies in this field. Specifically, in breast cancer, GR is considered a marker of poor prognosis, and a therapeutic target for the triple-negative breast cancer (TNBC) subtype, and efforts are being made to develop better GR antagonists with fewer side effects. It is necessary to know the type of breast cancer to differentiate the treatment for estrogen receptor (ER)-positive, ER-negative, and TNBC, to implement therapies that include the use of GCs.