RORalpha attenuates Wnt/beta-catenin signaling by PKCalpha-dependent phosphorylation in colon cancer

Retinoic acid receptor-related orphan receptor alpha and synthetic RORα agonist against invasion and metastasis in tongue squamous cell carcinoma

Retinoic acid receptor-related orphan receptor alpha (RORα), an essential tumor suppressor in a range of human malignancies, is classified as a member of the orphan nuclear receptor family. The most prevalent form of oral cancer, tongue squamous cell carcinoma (TSCC) is characterized by its severe malignancy and unfavorable prognosis. However, the extent to which its tumorigenesis mechanisms are associated with RORα expression levels is still not fully understood. The objective of this study was to examine the molecular mechanisms by which RORα is involved in TSCC. Through the use of immunohistochemistry (IHC), it was discovered that the expression level of RORα was significantly downregulated in TSCC tissues when compared to adjacent normal tissues in this study. To further investigate the role of RORα in TSCC, we activated the expression of RORα in human TSCC cell line (SCC9 cells) by transfecting RORα cDNA and using the selective RORα agonist SR1078. The results show that RORα can significantly inhibit the invasion, migration, proliferation, and adhesion of TSCC cells and induce cell apoptosis. In addition, xenograft models confirmed the conclusion that stable activation or treatment with SR1078 to increase RORα content significantly inhibited tumor growth and development. Taken together, this study provides solid evidence for the inhibitory role of RORα in the progression of TSCC. In addition, the preliminary application results of SR1078 in TSCC show that SR1078 is expected to be a potential therapeutic medication for TSCC. These findings provide innovative perspectives on the development of potential biomarkers and agents for TSCC therapy. The objective is to introduce novel strategy and alternatives for the prevention and treatment of TSCC.

Why Is Wnt/β-Catenin Not Yet Targeted in Routine Cancer Care?

Despite significant progress in cancer prevention, screening, and treatment, the still limited number of therapeutic options is an obstacle towards increasing the cancer cure rate. In recent years, many efforts were put forth to develop therapeutics that selectively target different components of the oncogenic Wnt/β-catenin signaling pathway. These include small molecule inhibitors, antibodies, and more recently, gene-based approaches. Although some of them showed promising outcomes in clinical trials, the Wnt/β-catenin pathway is still not targeted in routine clinical practice for cancer management. As for most anticancer treatments, a critical limitation to the use of Wnt/β-catenin inhibitors is their therapeutic index, i.e., the difficulty of combining effective anticancer activity with acceptable toxicity. Protecting healthy tissues from the effects of Wnt/β-catenin inhibitors is a major issue due to the vital role of the Wnt/β-catenin signaling pathway in adult tissue homeostasis and regeneration. In this review, we provide an up-to-date summary of clinical trials on Wnt/β-catenin pathway inhibitors, examine their anti-tumor activity and associated adverse events, and explore strategies under development to improve the benefit/risk profile of this therapeutic approach.

Regulation of RORα Stability through PRMT5-Dependent Symmetric Dimethylation

Retinoic acid receptor-related orphan receptor alpha (RORα), a candidate tumor suppressor, is prevalently downregulated or lost in malignant breast cancer cells. However, the mechanisms of how RORα expression is regulated in breast epithelial cells remain incompletely understood. Protein arginine N-methyltransferase 5 (PRMT5), a type II methyltransferase catalyzing the symmetric methylation of the amino acid arginine in target proteins, was reported to regulate protein stability. To study whether and how PRMT5 regulates RORα, we examined the direct interaction between RORα and PRMT5 by immunoprecipitation and GST pull-down assays. The results showed that PRMT5 directly bound to RORα, and PRMT5 mainly symmetrically dimethylated the DNA-binding domain (DBD) but not the ligand-binding domain (LBD) of RORα. To investigate whether RORα protein stability is regulated by PRMT5, we transfected HEK293FT cells with RORα and PRMT5-expressing or PRMT5-silencing (shPRMT5) vectors and then examined RORα protein stability by a cycloheximide chase assay. The results showed that PRMT5 increased RORα protein stability, while silencing PRMT5 accelerated RORα protein degradation. In PRMT5-silenced mammary epithelial cells, RORα protein expression was decreased, accompanied by an enhanced epithelial-mesenchymal transition morphology and cell invasion and migration abilities. In PRMT5-overexpressed mammary epithelial cells, RORα protein was accumulated, and cell invasion was suppressed. These findings revealed a novel mechanism by which PRMT5 regulates RORα protein stability.

RAR-related orphan receptor alpha and the staggerer mice: a fine molecular story

The retinoic acid-related orphan receptor alpha (RORα) protein first came into the limelight due to a set of staggerer mice, discovered at the Jackson Laboratories in the United States of America by Sidman, Lane, and Dickie (1962) and genetically deciphered by Hamilton et al. in 1996. These staggerer mice exhibited cerebellar defects, an ataxic gait, a stagger along with several other developmental abnormalities, compensatory mechanisms, and, most importantly, a deletion of 160 kilobases (kb), encompassing the RORα ligand binding domain (LBD). The discovery of the staggerer mice and the subsequent discovery of a loss of the LBD within the RORα gene of these mice at the genetic level clearly indicated that RORα's LBD played a crucial role in patterning during embryogenesis. Moreover, a chance study by Roffler-Tarlov and Sidman (1978) noted reduced concentrations of glutamic acid levels in the staggerer mice, indicating a possible role for the essence of a nutritionally balanced diet. The sequential organisation of the building blocks of intact genes, requires the nucleotide bases of deoxyribonucleic acid (DNA): purines and pyrimidines, both of which are synthesized, upon a constant supply of glutamine, an amino acid fortified in a balanced diet and a byproduct of the carbohydrate and lipid metabolic pathways. A nutritionally balanced diet, along with a metabolic "enzymatic machinery" devoid of mutations/aberrations, was essential in the uninterrupted transcription of RORα during embryogenesis. In addition to the above, following translation, a ligand-responsive RORα acts as a "molecular circadian regulator" during embryogenesis and not only is expressed selectively and differentially, but also promotes differential activity depending on the anatomical and pathological site of its expression. RORα is highly expressed in the central nervous system (CNS) and the endocrine organs. Additionally, RORα and the clock genes are core components of the circadian rhythmicity, with the expression of RORα fluctuating in a night-day-night sigmoidal pattern and undoubtedly serves as an endocrine-like, albeit "molecular-circadian regulator". Melatonin, a circadian hormone, along with tri-iodothyronine and some steroid hormones are known to regulate RORα-mediated molecular activity, with each of these hormones themselves being regulated rhythmically by the hypothalamic-pituitary axis (HPA). The HPA regulates the circadian rhythm and cyclical release of hormones, in a self-regulatory feedback loop. Irregular sleep-wake patterns affect circadian rhythmicity and the ability of the immune system to withstand infections. The staggerer mice with their thinner bones, an altered skeletal musculature, an aberrant metabolic profile, the ataxic gait and an underdeveloped cerebellar cortex; exhibited compensatory mechanisms, that not only allowed the survival of the staggerer mice, but also enhanced protection from microbial invasions and resistance to high-fat-diet induced obesity. This review has been compiled in its present form, more than 14 years later after a chromatin immunoprecipitation (ChIP) cloning and sequencing methodology helped me identify signal transducer and activator of transcription 5 (STAT5) target sequences, one of which was mapped to the first intron of the RORα gene. The 599-base-long sequence containing one consensus TTCNNNGAA (TTCN3GAA) gamma-activated sequence (GAS) and five other non-consensus TTN5AA sequences had been identified from the clones isolated from the STAT5 target sites (fragments) in human phytohemagglutinin-activated CD8+ T lymphocytes, during my doctoral studies between 2006 and 2009. Most importantly, preliminary studies noted a unique RORα expression profile, during a time-course study on the ribonucleic acid (RNA), extracted from human phytohemagglutinin (PHA) activated CD8+ T lymphocytes stimulated with interleukin-2 (IL-2). This review mainly focuses on the "staggerer mice" with one of its first roles materialising during embryogenesis, a molecular-endocrine mediated circadian-like regulatory process.

Wnt signaling: Modulating tumor-associated macrophages and related immunotherapeutic insights

Wnt signaling pathways are highly conserved cascades that mediate multiple biological processes through canonical or noncanonical pathways, from embryonic development to tissue maintenance, but they also contribute to the pathogenesis of numerous cancers. Recent studies have revealed that Wnt signaling pathways critically control the interplay between cancer cells and tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) and potentially impact the efficacy of cancer immunotherapy. In this review, we summarize the evidence that Wnt signaling pathways boost the maturation and infiltration of macrophages for immune surveillance in the steady state but also polarize TAMs toward immunosuppressive M2-like phenotypes for immune escape in the TME. Both cancer cells and TAMs utilize Wnt signaling to transmit signals, and this interaction is crucial for the carcinogenesis and progression of common solid cancers, such as colorectal, gastric, hepatocellular, breast, thyroid, prostate, kidney, and lung cancers; osteosarcoma; and glioma. Specifically, compared with those in solid cancers, Wnt signaling pathways play a distinct role in the pathogenesis of leukemia. Efforts to develop Wnt-based drugs for cancer treatment are still ongoing, and some indeed enhance the anticancer immune response. We believe that the combination of Wnt signaling-based therapy with conventional or immune therapies is a promising therapeutic approach and can facilitate personalized treatment for most cancers.

Protein kinase C signaling "in" and "to" the nucleus: Master kinases in transcriptional regulation

PKC is a multifunctional family of Ser-Thr kinases widely implicated in the regulation of fundamental cellular functions, including proliferation, polarity, motility, and differentiation. Notwithstanding their primary cytoplasmic localization and stringent activation by cell surface receptors, PKC isozymes impel prominent nuclear signaling ultimately impacting gene expression. While transcriptional regulation may be wielded by nuclear PKCs, it most often relies on cytoplasmic phosphorylation events that result in nuclear shuttling of PKC downstream effectors, including transcription factors. As expected from the unique coupling of PKC isozymes to signaling effector pathways, glaring disparities in gene activation/repression are observed upon targeting individual PKC family members. Notably, specific PKCs control the expression and activation of transcription factors implicated in cell cycle/mitogenesis, epithelial-to-mesenchymal transition and immune function. Additionally, PKCs isozymes tightly regulate transcription factors involved in stepwise differentiation of pluripotent stem cells toward specific epithelial, mesenchymal, and hematopoietic cell lineages. Aberrant PKC expression and/or activation in pathological conditions, such as in cancer, leads to profound alterations in gene expression, leading to an extensive rewiring of transcriptional networks associated with mitogenesis, invasiveness, stemness, and tumor microenvironment dysregulation. In this review, we outline the current understanding of PKC signaling "in" and "to" the nucleus, with significant focus on established paradigms of PKC-mediated transcriptional control. Dissecting these complexities would allow the identification of relevant molecular targets implicated in a wide spectrum of diseases.

Insertion/deletion (Indel) variant of the goat RORA gene is associated with growth traits

RAR related orphan receptor A (RORA), which encodes the retinoid-acid-related orphan receptor alpha (RORα), is a clock gene found in skeletal muscle. Several studies have shown that RORα plays an important role in bone formation, suggesting that RORA gene may take part in the regulation of growth and development. The purpose of this research is to study the insertion/deletion (indel) variations of the RORA gene and investigate the relationship with the growth traits of Shaanbei white cashmere (SBWC) goats. Herein, the current study identified that the P4-11-bp and P11-28-bp deletion sites are polymorphic among 12 pairs of primers within the RORA gene in the SBWC goats (n = 641). Moreover, the P11-28-bp deletion locus was significantly related to the body height (p = 0.046), height at hip cross (p = 0.012), and body length (p = 0.003). Both of P4-11-bp and P11-28-bp indels showed the moderate genetic diversity (0.25 Collapse

Key Words

• RAR related orphan receptor A (RORA)
• clock gene
• goat
• growth traits
• insertion/deletion

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MESH Headings

• Pregnancy
• Female
• Animals
• Litter Size/genetics
• Goats/physiology
• INDEL Mutation/genetics
• Phenotype

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Grants Collapse

Affiliation(s)

Qian Zhou College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
Huina Hu College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
Yuta Yang College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
Yuxin Kang College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
Xianyong Lan College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
Xianfeng Wu Institute of Animal Husbandry and Veterinary, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian, China
Zhengang Guo College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China Animal Husbandry and Veterinary Science Institute of Bijie city, Bijie, Guizhou, China
Chuanying Pan College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China

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The Roles of WNT Signaling Pathways in Skin Development and Mechanical-Stretch-Induced Skin Regeneration

The WNT signaling pathway plays a critical role in a variety of biological processes, including development, adult tissue homeostasis maintenance, and stem cell regulation. Variations in skin conditions can influence the expression of the WNT signaling pathway. In light of the above, a deeper understanding of the specific mechanisms of the WNT signaling pathway in different physiological and pathological states of the skin holds the potential to significantly advance clinical treatments of skin-related diseases. In this review, we present a comprehensive analysis of the molecular and cellular mechanisms of the WNT signaling pathway in skin development, wound healing, and mechanical stretching. Our review sheds new light on the crucial role of the WNT signaling pathway in the regulation of skin physiology and pathology.

Mitogen-Activated Protein Kinase and Exploratory Nuclear Receptor Crosstalk in Cancer Immunotherapy

The three major mitogen-activated protein kinase (MAPK) pathways (ERK1/2, p38, and JNK/SAPK) are upstream regulators of the nuclear receptor superfamily (NRSF). These ligand-activated transcription factors are divided into subclasses comprising receptors for endocrine hormones, metabolic compounds (e.g., vitamins, diet), xenobiotics, and mediators released from host immune reactions such as tissue injury and inflammation. These internal and external cues place the NRSF at the frontline as sensors and translators of information from the environment towards the genome. For most of the former "orphan" receptors, physiological and synthetic ligands have been identified, opening intriguing opportunities for combination therapies with existing cancer medications. Hitherto, only preclinical data are available, warranting further validation in clinical trials in patients. The current review summarized the existing literature covering the expression and function of NRSF subclasses in human solid tumors and hematopoietic malignancies and their modulatory effects on innate (e.g., macrophages, dendritic cells) and adaptive (i.e., T cell subsets) immune cells, encouraging mechanistic and pharmacological studies in combination with current clinically approved therapeutics against immune checkpoint molecules (e.g., PD1).

WNT5A: a double-edged sword in colorectal cancer progression

The Wnt signaling pathway is known to play a crucial role in cancer, and WNT5A is a member of this pathway that binds to the Frizzled (FZD) and Receptor Tyrosine Kinase-Like Orphan Receptor (ROR) family members to activate non-canonical Wnt signaling pathways. The WNT5A pathway is involved in various cellular processes, such as proliferation, differentiation, migration, adhesion, and polarization. In the case of colorectal cancer (CRC), abnormal activation or inhibition of WNT5A signaling can lead to both oncogenic and antitumor effects. Moreover, WNT5A is associated with inflammation, metastasis, and altered metabolism in cancer cells. This article aims to discuss the molecular mechanisms and dual roles of WNT5A in CRC.

Daphnanes diterpenes from the latex of Hura crepitans L. and their PKCζ-dependent anti-proliferative activity on colorectal cancer cells

Hura crepitans L. (Euphorbiaceae) is a thorn-covered tree widespread in South America, Africa and Asia which produces an irritating milky latex containing numerous secondary metabolites, notably daphnane-type diterpenes known as Protein Kinase C activators. Fractionation of a dichloromethane extract of the latex led to the isolation of five new daphnane diterpenes (1-5), along with two known analogs (6-7) including huratoxin. Huratoxin (6) and 4',5'-epoxyhuratoxin (4) were found to exhibit significant and selective cell growth inhibition against colorectal cancer cell line Caco-2 and primary colorectal cancer cells cultured as colonoids. The underlying mechanism of 4 and 6 was further investigated revealing the involvement of PKCζ in the cytostatic activity.

The Orphan GPR50 Receptor Regulates the Aggressiveness of Breast Cancer Stem-like Cells via Targeting the NF-kB Signaling Pathway

The expression of GPR50 in CSLC and several breast cancer cell lines was assessed by RT-PCR and online platform (UALCAN, GEPIA, and R2 gene analysis). The role of GPR50 in driving CSLC, sphere formation, cell proliferation, and migration was performed using shGPR50 gene knockdown, and the role of GPR50-regulated signaling pathways was examined by Western blotting and Luciferase Assay. Herein, we confirmed that the expression of G protein-coupled receptor 50 (GPR50) in cancer stem-like cells (CSLC) is higher than that in other cancer cells. We examined that the knockdown of GPR50 in CSLC led to decreased cancer properties, such as sphere formation, cell proliferation, migration, and stemness. GPR50 silencing downregulates NF-kB signaling, which is involved in sphere formation and aggressiveness of CSLC. In addition, we demonstrated that GPR50 also regulates ADAM-17 activity by activating NOTCH signaling pathways through the AKT/SP1 axis in CSLC. Overall, we demonstrated a novel GPR50-mediated regulation of the NF-κB-Notch signaling pathway, which can provide insights into CSLC progression and prognosis, and NF-κB-NOTCH-based CSLC treatment strategies.

Emerging Role of Plant-Based Dietary Components in Post-Translational Modifications Associated with Colorectal Cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide. Its main modifiable risk factors are diet, alcohol consumption, and smoking. Thus, the right approach through lifestyle changes may lead to its prevention. In fact, some natural dietary components have exhibited chemopreventive activity through modulation of cellular processes involved in CRC development. Although cancer is a multi-factorial process, the study of post-translational modifications (PTMs) of proteins associated with CRC has recently gained interest, as inappropriate modification is closely related to the activation of cell signalling pathways involved in carcinogenesis. Therefore, this review aimed to collect the main PTMs associated with CRC, analyse the relationship between different proteins that are susceptible to inappropriate PTMs, and review the available scientific literature on the role of plant-based dietary compounds in modulating CRC-associated PTMs. In summary, this review suggested that some plant-based dietary components such as phenols, flavonoids, lignans, terpenoids, and alkaloids may be able to correct the inappropriate PTMs associated with CRC and promote apoptosis in tumour cells.

Targeting the cholesterol-RORα/γ axis inhibits colorectal cancer progression through degrading c-myc

Dysregulated cholesterol metabolism is a hallmark of colorectal cancer (CRC). However, the usage of cholesterol-lowering agents seemed to have no benefit in CRC patients. In this study, we focused on the cholesterol-nuclear receptors (NRs) axis as a strategy. Cholesterol and its derivatives work as ligands for different nuclear receptors, thus promoting cancer progression. The key NR downstream of cholesterol in CRC is unknown. Here, we treated CRC cells with a cholesterol-lowering agent and lipoprotein-depleted conditioned medium, and then detected the change of the putative NRs. The results revealed that RORα/γ (Retinoic acid receptor-related Orphan Receptor α/γ) levels exhibited the most obvious increases in CRC cells subjected them to cholesterol deprivation. RORα/γ agonists significantly inhibited CRC cells proliferation and migration in vitro and in vivo. Also, RORα/γ overexpression repressed CRC cells proliferation and migration in vitro and in vivo and RORα/γ knockdown promoted it. Mechanistically, RORα/γ agonists promoted c-myc degradation by activating the transcription of the ubiquitinase NEDD4. Intriguingly, the combination of RORα/γ agonists and atorvastatin had a synergistic effect on inhibiting CRC cells. These findings demonstrate that the cholesterol- RORα/γ axis is important for maintaining c-myc protein levels. Combination therapy with atorvastatin and RORα/γ agonist is a promising therapeutic strategy for CRC.

ROS inhibits RORα degradation by decreasing its arginine methylation in liver cancer

Retinoic acid receptor-related orphan receptor α (RORα) is a transcription factor involved in nuclear gene expression and a known tumor suppressor. RORα was the first identified substrate of lysine methylation-dependent degradation. However, the mechanisms of other post-translational modifications (PTMs) that occur in RORα remain largely unknown, especially in liver cancer. Arginine methylation is a common PTM in arginine residues of nonhistone and histone proteins and affects substrate protein function and fate. We found an analogous amino acid disposition containing R37 at the ROR N-terminus compared to histone H3 residue, which is arginine methylated. Here, we provide evidence that R37 methylation-dependent degradation is carried out by protein arginine methyltransferase 5 (PRMT5). Further, we discovered that PRMT5 regulated the interaction between the E3 ubiquitin ligase ITCH and RORα through RORα arginine methylation. Arginine methylation-dependent ubiquitination-mediated RORα degradation reduced downstream target gene activation. H₂ O₂ -induced reactive oxygen species (ROS) decreased PRMT5 protein levels, consequently increasing RORα protein levels in HepG2 liver cancer cells. In addition, ROS inhibited liver cancer progression by inducing apoptosis via PRMT5-mediated RORα methylation and the ITCH axis. Our results potentiate PRMT5 as an elimination target in cancer therapy, and this additional regulatory level within ROS signaling may help identify new targets for therapeutic intervention in liver cancer.

Maresin-1 and Its Receptors RORα/LGR6 as Potential Therapeutic Target for Respiratory Diseases

Maresin-1 is one of the representative specialized pro-resolving mediators that has shown beneficial effects in inflammatory disease models. Recently, two distinct types of receptor molecules were discovered as the targets of maresin-1, further revealing the pro-resolution mechanism of maresin-1. One is retinoic acid-related orphan receptor α (RORα) and the another one is leucine-rich repeat domain-containing G protein-coupled receptor 6 (LGR6). In this review, we summarized the detailed role of maresin-1 and its two different receptors in respiratory diseases. RORα and LGR6 are potential targets for the treatment of respiratory diseases. Future basic research and clinical trials on MaR1 and its receptors should provide useful information for the treatment of respiratory diseases.

A novel anti-proliferative PKCα-Ras-ERK signaling axis in intestinal epithelial cells

We have previously shown that the serine/threonine kinase PKCα triggers MAPK/ERK kinase (MEK)-dependent G₁→S cell cycle arrest in intestinal epithelial cells, characterized by downregulation of cyclin D1 and inhibitor of DNA-binding protein 1 (Id1) and upregulation of the cyclin-dependent kinase inhibitor p21^Cip1. Here, we use pharmacological inhibitors, genetic approaches, siRNA-mediated knockdown, and immunoprecipitation to further characterize anti-proliferative ERK signaling in intestinal cells. We show that PKCα signaling intersects the Ras-Raf-MEK-ERK kinase cascade at the level of Ras small GTPases, and that anti-proliferative effects of PKCα require active Ras, Raf, MEK and ERK, core ERK pathway components that are also essential for pro-proliferative ERK signaling induced by epidermal growth factor (EGF). However, PKCα-induced anti-proliferative signaling differs from EGF signaling in that it is independent of the Ras guanine nucleotide exchange factors (Ras-GEFs), SOS1/2, and involves prolonged rather than transient ERK activation. PKCα forms complexes with A-Raf, B-Raf and C-Raf that dissociate upon pathway activation, and all three Raf isoforms can mediate PKCα-induced anti-proliferative effects. At least two PKCα-ERK pathways that collaborate to promote growth arrest were identified: one pathway requiring the Ras-GEF, RasGRP3, and H-Ras, leads to p21^Cip1 upregulation, while additional pathway(s) mediate PKCα-induced cyclin D1 and Id1 downregulation. PKCα also induces ERK-dependent SOS1 phosphorylation, indicating possible negative crosstalk between anti-proliferative and growth-promoting ERK signaling. Importantly, the spatio-temporal activation of PKCα and ERK in the intestinal epithelium in vivo supports the physiological relevance of these pathways and highlights the importance of anti-proliferative ERK signaling to tissue homeostasis in the intestine.

Retinoid orphan nuclear receptor alpha (RORα) suppresses the epithelial-mesenchymal transition (EMT) by directly repressing Snail transcription

Retinoid orphan nuclear receptor alpha (RORα) is a member of the orphan nuclear factor family and regulates gene expression by binding to ROR response elements (ROREs). RORα has been identified as a potential tumor suppressor; however, how downregulation of RORα promotes cancer progression is not fully understood. Here, we showed that protein levels of RORα were downregulated during the Snail-, Twist-, or transforming growth factor-β–induced epithelial–mesenchymal transition (EMT). We found that silencing of RORα induced expression of mesenchymal markers in MCF10A cells, accompanied by enhanced cell invasion, migration, and mammosphere formation. Furthermore, ectopic expression of RORα suppressed transforming growth factor-β–induced EMT processes in MCF10A and HMLE cells. These results indicate that downregulation of RORα is crucial for the induction of EMT in mammary epithelial cells. By analyzing gene expression profiles in control and RORα-expressing cells, we also identified Snail, a key regulator of EMT, as a potential target of RORα. We show that RORα expression significantly inhibits Snail transcription in breast cancer cells. Chromatin immunoprecipitation analysis demonstrated that RORα bound to the ROREs in promoter region of SNAI1 gene, and using the luciferase reporter assay, we showed that binding to the ROREs was critical for RORα to repress Snail transcription. Finally, rescue experiments substantiated that Snail mediates RORα function in suppressing EMT and mammosphere formation. These results reveal a novel function of RORα in suppressing EMT and identify Snail as a direct target of RORα in mammary epithelial cells.

Plasma circRNA microarray profiling identifies novel circRNA biomarkers for the diagnosis of ovarian cancer

Background

Circular RNA (circRNA), a class of RNA with a covalent closed circular structure that widely existed in serum and plasma, has been considered an ideal liquid biopsy marker in many diseases. In this study, we employed microarray and qRT-PCR to evaluate the potential circulating circRNAs with diagnostic efficacy in ovarian cancer.

Methods

We used microarray to explore the circRNA expression profile in ovarian cancer patients’ plasma and quantitative real-time (qRT)-PCR approach to assessing the candidate circRNA’s expression. Then the receiver operating characteristic (ROC) curve was employed to analyze the diagnostic values of candidate circRNAs. The diagnostic model circCOMBO was a combination of hsa_circ_0003972 and hsa_circ_0007288 built by binary logistic regression. Then bioinformatic tools were used to predict their potential mechanisms.

Results

Hsa_circ_0003972 and hsa_circ_0007288 were downregulated in ovarian cancer patients’ plasma, tissues, and cell lines, comparing with the controls. Hsa_circ_0003972 and hsa_circ_0007288 exhibited diagnostic values with the Area Under Curve (AUC) of 0.724 and 0.790, respectively. circCOMBO showed a better diagnostic utility (AUC: 0.781), while the combination of circCOMBO and carbohydrate antigen 125 (CA125) showed the highest diagnostic value (AUC: 0.923). Furthermore, the higher expression level of hsa_circ_0007288 in both plasma and ovarian cancer tissues was associated with lower lymph node metastasis potential in ovarian cancer.

Conclusions

Our results revealed that hsa_circ_0003972 and hsa_circ_0007288 may serve as novel circulating biomarkers for ovarian cancer diagnosis.

Supplementary information

The online version contains supplementary material available at 10.1186/s13048-022-00988-0.

POU6F1 cooperates with RORA to suppress the proliferation of lung adenocarcinoma by downregulation HIF1A signaling pathway

Lung adenocarcinoma (LUAD) represents the most frequently diagnosed histological subtype of non-small cell lung cancer with the highest mortality worldwide. Transcriptional dysregulation is a hallmark of nearly all kinds of cancers. In the study, we identified that the POU domain, class 6, transcription factor 1 (POU6F1), a member of the POU family of transcription factors, was closely associated with tumor stage and death in LUAD. We revealed that POU6F1 was downregulated in LUAD tissues and downregulated POU6F1 was predictive of an unfavorable prognosis in LUAD patients. In vitro assays, including CCK8, soft agar, transwell, clone formation, wound-healing assay, and nude mouse xenograft model all revealed that POU6F1 inhibited the growth and invasion of LUAD cells. Mechanistically, POU6F1 bound and stabilized retinoid-related orphan receptor alpha (RORA) to exert the transcriptional inhibition of hypoxia-inducible factor 1-alpha (HIF1A) and alter the expression of HIF1A signaling pathway-associated genes, including ENO1, PDK1, and PRKCB, thereby leading to the suppression of LUAD cells. Collectively, these results demonstrated the suppressive role of POU6F1/RORA in the progression of LUAD and may potentially be used as a target for the treatment of LUAD.

The value of WNT5A as prognostic and immunological biomarker in pan-cancer

Background

Finding new immune-related biomarkers is one of the promising research directions for tumor immunotherapy. The WNT5A gene could stimulate the WNT pathway and regulate the progression of various tumors. Recent studies have partially revealed the relationship between WNT5A and tumor immunity, but the correlation and underlying mechanisms in pan-cancer remain obscure. Thus, we conducted this study aiming to characterize the prognostic value and immunological portrait of WNT5A in cancer.

Methods

The data obtained from The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), and Cancer Cell Line Encyclopedia (CCLE) databases was utilized to analyze WNT5A expression levels by Kruskal-Wallis test and correlation to prognosis by Cox regression test and Kaplan-Meier test, while the data was also used to study the association between WNT5A expression and immune microenvironment, immune neoantigens, immune checkpoints, tumor mutational burden (TMB), and microsatellite instability (MSI) in pan-cancer. Gene set enrichment analysis (GSEA) was used to clarify the relevant signaling pathways. The R package was used for data analysis and to create the plots.

Results

The pan-cancer analysis revealed that the expression level of WNT5A is generally elevated in most tumors (19/34, 55.88%), and high WNT5A expression was correlated with poor prognosis in esophageal carcinoma (ESCA, P<0.05), low-grade glioma (LGG, P<0.01), adrenocortical carcinoma (ACC, P<0.01), pancreatic adenocarcinoma (PAAD, P<0.01), and head and neck squamous cell carcinoma (HNSC, P<0.05). In addition, WNT5A expression was positively associated with immune infiltration, stromal score, and immune checkpoints in most cancers, and correlated to immune neoantigens, TMB, and MSI. Finally, GSEA indicated that WNT5A is implicated in the transforming growth factor β (TGFβ), Notch, and Hedgehog signaling pathways, which may be related to tumor immunity.

Conclusions

The expression of WNT5A is elevated in most tumors and associated with tumor prognosis. Furthermore, WNT5A is associated with tumor immunity and may be an immunological biomarker in cancer.

Phosphorylation-Dependent Regulation of WNT/Beta-Catenin Signaling

WNT/β-catenin signaling is a highly complex pathway that plays diverse roles in various cellular processes. While WNT ligands usually signal through their dedicated Frizzled receptors, the decision to signal in a β-catenin-dependent or -independent manner rests upon the type of co-receptors used. Canonical WNT signaling is β-catenin-dependent, whereas non-canonical WNT signaling is β-catenin-independent according to the classical definition. This still holds true, albeit with some added complexity, as both the pathways seem to cross-talk with intertwined networks that involve the use of different ligands, receptors, and co-receptors. β-catenin can be directly phosphorylated by various kinases governing its participation in either canonical or non-canonical pathways. Moreover, the co-activators that associate with β-catenin determine the output of the pathway in terms of induction of genes promoting proliferation or differentiation. In this review, we provide an overview of how protein phosphorylation controls WNT/β-catenin signaling, particularly in human cancer.

RORα and REV-ERBα are Associated With Clinicopathological Parameters and are Independent Biomarkers of Prognosis in Gastric Cancer

Retinoid-related orphan receptor alpha (RORα) and nuclear receptor subfamily 1 group D member 1 (REV-ERBα) play critical roles in many human cancers. Whether RORα and REV-ERBα expression levels are associated with clinical characteristics are poorly understood, and they may be independent predictors of overall survival (OS) and progression-free survival (PFS) in gastric cancer (GC). This study aimed to investigate the correlation of RORα and REV-ERBα expression levels with clinicopathological parameters, OS, and PFS in GC. Immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were employed to assess the expression levels of RORα and REV-ERBα, which were downregulated in GC tissues compared with normal gastric tissues (P < .001; P < .001) and were associated with several clinicopathological parameters, including histological grade (P = .032; P < .001), preoperative carcinoembryonic antigen (CEA) levels (P = .004; P < .001), and tumor-node-metastasis (TNM) stage (P = .015; P < .001). Additionally, low RORα and REV-ERBα expression levels were associated with poor OS and PFS in GC patients, respectively (P < .001; P = .001). Furthermore, univariate Cox regression model analysis showed that histological grade (P < .001; P < .001), preoperative CEA levels (P < .001; P = .001), TNM stage (P < .001; P < .001), lymph node metastasis (P = .002; P = .002), RORα expression levels (P = .001; P < .001), and REV-ERBα expression levels (P < .001; P = .001) were associated with OS and PFS in GC. Multivariate Cox regression model analysis indicated that RORα expression levels and REV-ERBα expression levels are independent factors of OS and PFS in GC. Besides, RORα and REV-ERBα expression may be positively correlated (χ² = 6.835; P = .009), and GC patients with both high RORα and REV-ERBα expression levels had the best prognosis. In conclusion, RORα and REV-ERBα may coparticipate in tumor activities and show potential to estimate the prognosis of GC.

Identification of the RORα Transcriptional Network Contributes to the Search for Therapeutic Targets in Atherosclerosis

The retinoic acid receptor-related orphan receptor α (RORα) is involved in the regulation of several physiological processes, including development, metabolism, and circadian rhythm. RORα-deficient mice display profound atherosclerosis, in which hypoalphalipoproteinemia is reportedly associated with decreased plasma levels of high-density lipoprotein, increased levels of inflammatory cytokines, and ischemia/reperfusion-induced damage. The recent characterization of endogenous ligands (including cholesterol, oxysterols, provitamin D₃, and their derivatives), mediators, and initiation complexes associated with the transcriptional regulation of these orphan nuclear receptors has facilitated the development of synthetic ligands. These findings have also highlighted the potential of application of RORα as a therapeutic target for several diseases, including diabetes, dyslipidemia, and atherosclerosis. In this review, the current literature related to the structure and function of RORα, its genetic inter-individual differences, and its potential as a therapeutic target in atherosclerosis is discussed.

Protein kinase A Mediated Effects of Protein kinase C Partial Agonist HMI-1a3 in Colorectal Cancer Cells

Colorectal cancer is the third most commonly occurring cancer in men and the second in women. The global burden of colorectal cancer is projected to increase to over 2 million new cases with over 1 million deaths within the next 10 years and there is a great need for new compounds with novel mechanisms of action. Our group has developed PKC modulating isophthalic acid derivatives that induce cytotoxicity towards human cervical and prostate cancer cell lines. In this study, we investigated the effects of 5-(hydroxymethyl)isophthalate 1a3 (HMI-1a3) on colorectal cancer cell lines (Caco2, Colo205 and HT29). HMI-1a3 inhibited cell proliferation, decreased cell viability and induced an apoptotic response in all studied cell lines. These effects, however, were independent of PKC. Using serine/threonine kinome profiling and pharmacological kinase inhibitors we identified activation of the cAMP/PKA pathway as a new mechanism-of-action for HMI-1a3-induced anti-cancer activity in colorectal cancer cell lines. Our current results strengthen the hypothesis for HMI-1a3 as a potential anti-cancer agent against various malignancies. Significance Statement Colorectal cancer (CRC) is a common solid organ malignancy. Here, we demonstrate that the protein kinase C (PKC) C1 domain-targeted isophthalatic acid derivative HMI-1a3 has anti-cancer activity on CRC cell lines independently of PKC. We identified protein kinase A (PKA) activation as a mechanism of HMI-1a3 induced anti-cancer effects. Our results reveal a new anti-cancer mechanism of action for the partial PKC agonist HMI-1a3 and thus provide new insights for the development of PKC and PKA modulators for cancer therapy.

CircGSK3B promotes RORA expression and suppresses gastric cancer progression through the prevention of EZH2 trans-inhibition

BACKGROUND

Circular RNAs (circRNAs) are a class of non-coding RNA that play critical roles in the development and pathogenesis of various cancers. The circRNA circGSK3B (hsa_circ_0003763) has been shown to enhance cell proliferation, migration, and invasion in hepatocellular carcinoma. However, the specific functions and underlying mechanistic involvement of circGSK3B in gastric cancer (GC) have not yet been explored. Our study aimed to investigate the effect of circGSK3B on the progression of GC and to identify any potential mechanisms underlying this process.

METHODS

CircRNA datasets associated with GC were obtained from the PubMed, GEO, and ArrayExpress databases, and circRNAs were validated via RT-qPCR and Sanger sequencing. Biotin-labeled RNA pull-down, mass spectrometry, RNA immunoprecipitation, and in vitro binding assays were employed to determine proteins demonstrating interactions with circGSK3B. Gene expression regulation was assessed through RT-qPCR, chromatin immunoprecipitation, and western blot assays. Gain- and loss-of-function assays were used to analyze any effects of circGSK3B and its partner regulatory molecule (EZH2) on the proliferation, invasion, and migration abilities of GC cells both in vitro and in vivo.

RESULTS

CircGSK3B was mainly identified in the nucleus. This circRNA was present at a reduced concentration in GC tissues and cell lines. Overexpression of circGSK3B was shown to inhibit the growth, invasion, and metastasis of GC cells both in vitro and in vivo. Mechanistically, circGSK3B directly interacted with EZH2, acting to suppress the binding of EZH2 and H3K27me3 to the RORA promoter, and leading to an elevation in RORA expression and ultimately the suppression of GC progression.

CONCLUSIONS

CircGSK3B acts as a tumor suppressor, reducing EZH2 trans-inhibition and GC progression. This demonstrates the potential use of this RNA as a therapeutic target for GC.

Unraveling the physiological roles of retinoic acid receptor-related orphan receptor α

Retinoic acid receptor-related orphan receptor-α (RORα) is a member of the orphan nuclear receptor family and functions as a transcriptional activator in response to circadian changes. Circadian rhythms are complex cellular mechanisms regulating diverse metabolic, inflammatory, and tumorigenic gene expression pathways that govern cyclic cellular physiology. Disruption of circadian regulators, including RORα, plays a critical role in tumorigenesis and facilitates the development of inflammatory hallmarks. Although RORα contributes to overall fitness among anticancer, anti-inflammatory, lipid homeostasis, and circadian clock mechanisms, the molecular mechanisms underlying the mode of transcriptional regulation by RORα remain unclear. Nonetheless, RORα has important implications for pharmacological prevention of cancer, inflammation, and metabolic diseases, and understanding context-dependent RORα regulation will provide an innovative approach for unraveling the functional link between cancer metabolism and rhythm changes.

Clair D, Li JD, Xu R. RORα Suppresses Cancer-Associated Inflammation by Repressing Respiratory Complex I-Dependent ROS Generation

Breast cancer development is associated with macrophage infiltration and differentiation in the tumor microenvironment. Our previous study highlights the crucial function of reactive oxygen species (ROS) in enhancing macrophage infiltration during the disruption of mammary tissue polarity. However, the regulation of ROS and ROS-associated macrophage infiltration in breast cancer has not been fully determined. Previous studies identified retinoid orphan nuclear receptor alpha (RORα) as a potential tumor suppressor in human breast cancer. In the present study, we showed that retinoid orphan nuclear receptor alpha (RORα) significantly decreased ROS levels and inhibited ROS-mediated cytokine expression in breast cancer cells. RORα expression in mammary epithelial cells inhibited macrophage infiltration by repressing ROS generation in the co-culture assay. Using gene co-expression and chromatin immunoprecipitation (ChIP) analyses, we identified complex I subunits NDUFS6 and NDUFA11 as RORα targets that mediated its function in suppressing superoxide generation in mitochondria. Notably, the expression of RORα in 4T1 cells significantly inhibited cancer metastasis, reduced macrophage accumulation, and enhanced M1-like macrophage differentiation in tumor tissue. In addition, reduced RORα expression in breast cancer tissue was associated with an increased incidence of cancer metastasis. These results provide additional insights into cancer-associated inflammation, and identify RORα as a potential target to suppress ROS-induced mammary tumor progression.

Inhibition of nuclear receptor RORα attenuates cartilage damage in osteoarthritis by modulating IL-6/STAT3 pathway

Osteoarthritis (OA) is characterized by cartilage destruction, chronic inflammation, and local pain. Evidence showed that retinoic acid receptor-related orphan receptor-α (RORα) is crucial in cartilage development and OA pathogenesis. Here, we investigated the role and molecular mechanism of RORα, an important member of the nuclear receptor family, in regulating the development of OA pathologic features. Investigation into clinical cartilage specimens showed that RORα expression level is positively correlated with the severity of OA and cartilage damage. In an in vivo OA model induced by anterior crucial ligament transaction, intra-articular injection of si-Rora adenovirus reversed the cartilage damage. The expression of cartilage matrix components type II collagen and aggrecan were elevated upon RORα blockade. RNA-seq data suggested that the IL-6/STAT3 pathway is significantly downregulated, manifesting the reduced expression level of both IL-6 and phosphorylated STAT3. RORα exerted its effect on IL-6/STAT3 signaling in two different ways, including interaction with STAT3 and IL-6 promoter. Taken together, our findings indicated the pivotal role of the RORα/IL-6/STAT3 axis in OA progression and confirmed that RORα blockade improved the matrix catabolism in OA chondrocytes. These results may provide a potential treatment target in OA therapy.

Restoration of the molecular clock is tumor suppressive in neuroblastoma

MYCN activation is a hallmark of advanced neuroblastoma (NB) and a known master regulator of metabolic reprogramming, favoring NB adaptation to its microenvironment. We found that the expression of the main regulators of the molecular clock loops is profoundly disrupted in MYCN-amplified NB patients, and this disruption independently predicts poor clinical outcome. MYCN induces the expression of clock repressors and downregulates the one of clock activators by directly binding to their promoters. Ultimately, MYCN attenuates the molecular clock by suppressing BMAL1 expression and oscillation, thereby promoting cell survival. Reestablishment of the activity of the clock activator RORα via its genetic overexpression and its stimulation through the agonist SR1078, restores BMAL1 expression and oscillation, effectively blocks MYCN-mediated tumor growth and de novo lipogenesis, and sensitizes NB tumors to conventional chemotherapy. In conclusion, reactivation of RORα could serve as a therapeutic strategy for MYCN-amplified NBs by blocking the dysregulation of molecular clock and cell metabolism mediated by MYCN.

Roles of Melatonin in Goat Hair Follicle Stem Cell Proliferation and Pluripotency Through Regulating the Wnt Signaling Pathway

Emerging studies show that melatonin promotes cashmere development through hypodermic implantation. However, the impact and underlying mechanisms are currently unknown. In vitro study has previously demonstrated that melatonin induces cashmere growth by regulating the proliferation of goat secondary hair follicle stem cells (gsHFSCs), but there is limited information concerning the effects of melatonin on cell pluripotency. It is also known that Wnt signaling may actively participate in regulating cell proliferation and stem cell pluripotency. Therefore, in the current investigation, goat hair follicle stem cells were exposed to multiple concentrations of melatonin and different culture times to reveal the relationship between melatonin and the activation of Wnt signaling. A proportionally high Catenin beta-1 (CTNNB1) response was induced by 500 ng/L of melatonin, but it was then suppressed with the dosages over 1,000 ng/L. Greater amounts of CTNNB1 entered the cell nuclei by extending the exposure time to 72 h, which activated transcription factor 4/lymphoid enhancer-binding factor 1 and promoted the expression of the proliferation-related genes C-MYC, C-JUN, and CYCLIND1. Moreover, nuclear receptor ROR-alpha (RORα) and bone morphogenetic protein 4 (BMP4) were employed to analyze the underlying mechanism. RORα presented a sluggish concentration/time-dependent rise, but BMP4 was increased dramatically by melatonin exposure, which revealed that melatonin might participate in regulating the pluripotency of hair follicle stem cells. Interestingly, NOGGIN, which is a BMP antagonist and highly relevant to cell stemness, was also stimulated by melatonin. These findings demonstrated that melatonin exposure and/or NOGGIN overexpression in hair follicle stem cells might promote the expression of pluripotency markers Homeobox protein NANOG, Organic cation/carnitine transporter 4, and Hematopoietic progenitor cell antigen CD34. Our findings here provided a comprehensive view of Wnt signaling in melatonin stimulated cells and melatonin mediated stemness of gsHFSCs by regulating NOGGIN, which demonstrates a regulatory mechanism of melatonin enhancement on the growth of cashmere.

The complex role of Wnt ligands in type 2 diabetes mellitus and related complications

Type 2 diabetes mellitus (T2DM) is one of the major chronic diseases, whose prevalence is increasing dramatically worldwide and can lead to a range of serious complications. Wnt ligands (Wnts) and their activating Wnt signalling pathways are closely involved in the regulation of various processes that are important for the occurrence and progression of T2DM and related complications. However, our understanding of their roles in these diseases is quite rudimentary due to the numerous family members of Wnts and conflicting effects via activating the canonical and/or non-canonical Wnt signalling pathways. In this review, we summarize the current findings on the expression pattern and exact role of each human Wnt in T2DM and related complications, including Wnt1, Wnt2, Wnt2b, Wnt3, Wnt3a, Wnt4, Wnt5a, Wnt5b, Wnt6, Wnt7a, Wnt7b, Wnt8a, Wnt8b, Wnt9a, Wnt9b, Wnt10a, Wnt10b, Wnt11 and Wnt16. Moreover, the role of main antagonists (sFRPs and WIF-1) and coreceptor (LRP6) of Wnts in T2DM and related complications and main challenges in designing Wnt-based therapeutic approaches for these diseases are discussed. We hope a deep understanding of the mechanistic links between Wnt signalling pathways and diabetic-related diseases will ultimately result in a better management of these diseases.

Epigenetic Regulation in Breast Cancer

Aberrant epigenetic alteration has been associated with development of various cancers, including breast cancer. Since epigenetic modifications such as DNA methylation and histone modification are reversible, epigenetic enzymes, including histone modifying enzymes and DNA methyltransferases, emerge as attractive targets for cancer therapy. Although epi-drugs targeting histone deacetylation or DNA methylation have received FDA approval for cancer therapy, a very modest anti-tumor activity has been observed with monotherapy in clinical studies of breast cancer. To improve efficacy of epi-drugs in breast cancer, combination of epi-drugs with other therapies currently has been investigated. Additionally, basic researches to elucidate molecular causes of cancer should be extensively and intensively conducted in order to find novel epigenetic druggable targets. In this chapter, we summarize how epigenetic regulation affects the development of breast cancer and how to control cancer phenotype by modulating abnormal epigenetic modifications, and then suggest future research directions in epigenetics for breast cancer treatment.

The complexities of PKCα signaling in cancer

Protein kinase C α (PKCα) is a ubiquitously expressed member of the PKC family of serine/threonine kinases with diverse functions in normal and neoplastic cells. Early studies identified anti-proliferative and differentiation-inducing functions for PKCα in some normal tissues (e.g., regenerating epithelia) and pro-proliferative effects in others (e.g., cells of the hematopoietic system, smooth muscle cells). Additional well documented roles of PKCα signaling in normal cells include regulation of the cytoskeleton, cell adhesion, and cell migration, and PKCα can function as a survival factor in many contexts. While a majority of tumors lose expression of PKCα, others display aberrant overexpression of the enzyme. Cancer-related mutations in PKCα are uncommon, but rare examples of driver mutations have been detected in certain cancer types (e. g., choroid gliomas). Here we review the role of PKCα in various cancers, describe mechanisms by which PKCα affects cancer-related cell functions, and discuss how the diverse functions of PKCα contribute to tumor suppressive and tumor promoting activities of the enzyme. We end the discussion by addressing mutations and expression of PKCα in tumors and the clinical relevance of these findings.

WNT5a in Colorectal Cancer: Research Progress and Challenges

Despite the clinical development of new adjuvant and neoadjuvant chemotherapy drugs, colorectal cancer is still one of the leading causes of cancer-related death in human beings. WNT5a, an autocrine and paracrine β-catenin independent ligand, has been shown to induce tumor inhibition and carcinogenic signals, depending on the type of cancer. In patients with colorectal cancer, WNT5a triggers a variety of downstream signaling pathways, which mainly affect the migration and invasion of tumor cells. This article reviews the mechanism and therapeutic potential of WNT5a in colorectal cancer. In short, an in-depth understanding of the role of WNT5a in colorectal cancer is very helpful to better deal with this disease.

Identification of a circadian gene signature that predicts overall survival in lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD) is one of the most common subtypes of lung cancer which is the leading cause of death in cancer patients. Circadian clock disruption has been listed as a likely carcinogen. However, whether the expression of circadian genes affects overall survival (OS) in LUAD patients remains unknown. In this article, we identified a circadian gene signature to predict overall survival in LUAD.

METHODS

RNA sequencing (HTSeq-FPKM) data and clinical characteristics were obtained for a cohort of LUAD patients from The Cancer Genome Atlas (TCGA). A multigene signature based on differentially expressed circadian clock-related genes was generated for the prediction of OS using Least Absolute Shrinkage and Selection Operator (LASSO)-penalized Cox regression analysis, and externally validated using the GSE72094 dataset from the GEO database.

RESULTS

Five differentially expressed genes (DEGs) were identified to be significantly associated with OS using univariate Cox proportional regression analysis (P < 0.05). Patients classified as high risk based on these five DEGs had significantly lower OS than those classified as low risk in both the TGCA cohort and GSE72094 dataset (P < 0.001). Multivariate Cox regression analysis revealed that the five-gene-signature based risk score was an independent predictor of OS (hazard ratio > 1, P < 0.001). Receiver operating characteristic (ROC) curves confirmed its prognostic value. Gene set enrichment analysis (GSEA) showed that Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to cell proliferation, gene damage repair, proteasomes, and immune and autoimmune diseases were significantly enriched.

CONCLUSION

A novel circadian gene signature for OS in LUAD was found to be predictive in both the derivation and validation cohorts. Targeting circadian genes is a potential therapeutic option in LUAD.

Angiogenesis-Related Functions of Wnt Signaling in Colorectal Carcinogenesis

Simple Summary

Angiogenesis belongs to the most clinical characteristics of colorectal cancer (CRC) and is strongly linked to the activation of Wnt/β-catenin signaling. The most prominent factors stimulating constitutive activation of this pathway, and in consequence angiogenesis, are genetic alterations (mainly mutations) concerning APC and the β-catenin encoding gene (CTNNB1), detected in a large majority of CRC patients. Wnt/β-catenin signaling is involved in the basic types of vascularization (sprouting and nonsprouting angiogenesis), vasculogenic mimicry as well as the formation of mosaic vessels. The number of known Wnt/β-catenin signaling components and other pathways interacting with Wnt signaling, regulating angiogenesis, and enabling CRC progression continuously increases. This review summarizes the current knowledge about the role of the Wnt/Fzd/β-catenin signaling pathway in the process of CRC angiogenesis, aiming to improve the understanding of the mechanisms of metastasis as well as improvements in the management of this cancer.

Abstract

Aberrant activation of the Wnt/Fzd/β-catenin signaling pathway is one of the major molecular mechanisms of colorectal cancer (CRC) development and progression. On the other hand, one of the most common clinical CRC characteristics include high levels of angiogenesis, which is a key event in cancer cell dissemination and distant metastasis. The canonical Wnt/β-catenin downstream signaling regulates the most important pro-angiogenic molecules including vascular endothelial growth factor (VEGF) family members, matrix metalloproteinases (MMPs), and chemokines. Furthermore, mutations of the β-catenin gene associated with nuclear localization of the protein have been mainly detected in microsatellite unstable CRC. Elevated nuclear β-catenin increases the expression of many genes involved in tumor angiogenesis. Factors regulating angiogenesis with the participation of Wnt/β-catenin signaling include different groups of biologically active molecules including Wnt pathway components (e.g., Wnt2, DKK, BCL9 proteins), and non-Wnt pathway factors (e.g., chemoattractant cytokines, enzymatic proteins, and bioactive compounds of plants). Several lines of evidence argue for the use of angiogenesis inhibition in the treatment of CRC. In the context of this paper, components of the Wnt pathway are among the most promising targets for CRC therapy. This review summarizes the current knowledge about the role of the Wnt/Fzd/β-catenin signaling pathway in the process of CRC angiogenesis, aiming to improve the understanding of the mechanisms of metastasis as well as improvements in the management of this cancer.

The Wnt Signalling Pathway: A Tailored Target in Cancer

Cancer is one of the greatest public health challenges. According to the World Health Organization (WHO), 9.6 million cancer deaths have been reported in 2018. The most common cancers include lung, breast, colorectal, prostate, skin (non-melanoma) and stomach cancer. The unbalance of physiological signalling pathways due to the acquisition of mutations in tumour cells is considered the most common cancer driver. The Wingless-related integration site (Wnt)/β-catenin pathway is crucial for tissue development and homeostasis in all animal species and its dysregulation is one of the most relevant events linked to cancer development and dissemination. The canonical and the non-canonical Wnt/β-catenin pathways are known to control both physiological and pathological processes, including cancer. Herein, the impact of the Wnt/β-catenin cascade in driving cancers from different origin has been examined. Finally, based on the impact of Extracellular Vesicles (EVs) on tumour growth, invasion and chemoresistance, and their role as tumour diagnostic and prognostic tools, an overview of the current knowledge linking EVs to the Wnt/β-catenin pathway is also discussed.

Transcriptional Regulation of Wnt/β-Catenin Pathway in Colorectal Cancer

The Wnt/β-catenin signaling pathway exerts integral roles in embryogenesis and adult homeostasis. Aberrant activation of the pathway is implicated in growth-associated diseases and cancers, especially as a key driver in the initiation and progression of colorectal cancer (CRC). Loss or inactivation of Adenomatous polyposis coli (APC) results in constitutive activation of Wnt/β-catenin signaling, which is considered as an initiating event in the development of CRC. Increased Wnt/β-catenin signaling is observed in virtually all CRC patients, underscoring the importance of this pathway for therapeutic intervention. Prior studies have deciphered the regulatory networks required for the cytoplasmic stabilisation or degradation of the Wnt pathway effector, β-catenin. However, the mechanism whereby nuclear β-catenin drives or inhibits expression of Wnt target genes is more diverse and less well characterised. Here, we describe a brief synopsis of the core canonical Wnt pathway components, set the spotlight on nuclear mediators and highlight the emerging role of chromatin regulators as modulators of β-catenin-dependent transcription activity and oncogenic output.

RORα Regulates Cholesterol Metabolism of CD8+ T Cells for Anticancer Immunity

Retinoic acid-related orphan receptor α (RORα) functions as a transcription factor for various biological processes, including circadian rhythm, inflammation, cancer, and lipid metabolism. Here, we demonstrate that RORα is crucial for maintaining cholesterol homeostasis in CD8⁺ T cells by attenuating NF-κB transcriptional activity. Cholesterol sulfate, the established natural agonist of RORα, exhibits cellular cytotoxicity on, and increased effector responses in, CD8⁺ T cells. Transcript analysis reveals that the suppression of RORα leads to the upregulation of NF-κB target genes in T cells. Chromatin immunoprecipitation analysis was used to determine the corecruitment of RORα and histone deacetylase (HDAC) on NF-κB target promoters and the subsequent dismissal of coactivators for transcriptional repression. We demonstrate that RORα/HDAC-mediated attenuation of NF-κB signaling controls the balance of cholesterol metabolism in CD8⁺ T cells, and that therapeutic strategies targeting this epigenetic regulation could be beneficial to the treatment of solid tumors including colon cancers.

GPR50 Promotes Hepatocellular Carcinoma Progression via the Notch Signaling Pathway through Direct Interaction with ADAM17

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide, and it is thus critical to identify novel molecular biomarkers of HCC prognosis and elucidate the molecular mechanisms underlying HCC progression. Here, we show that G-protein-coupled receptor 50 (GPR50) in HCC is overexpressed and that GPR50 knockdown may downregulate cancer cell progression through attenuation of the Notch signaling pathway. GPR50 knockdown was found to reduce HCC progression by inactivating Notch signaling in a ligand-independent manner through a disintegrin and metalloproteinase metallopeptidase domain 17 (ADAM17), a proteolytic enzyme that cleaves the Notch receptor, which was corroborated by GPR50 overexpression in hepatocytes. GPR50 silencing also downregulated transcription and translation of ADAM17 through the AKT/specificity protein-1 (SP1) signaling axis. Notably, GPR50 was found to directly interact with ADAM17. Overall, we demonstrate a novel GPR50-mediated regulation of the ADAM17-Notch signaling pathway, which can provide insights into HCC progression and prognosis and development of Notch-based HCC treatment strategies.

Non-canonical WNT5a regulates Epithelial-to-Mesenchymal Transition in the mouse ovarian surface epithelium

The ovarian surface epithelium (OSE) is a monolayer that covers the ovarian surface and is involved in ovulation by rupturing and enabling release of a mature oocyte and by repairing the wound after ovulation. Epithelial-to-mesenchymal transition (EMT) is a mechanism that may promote wound healing after ovulation. While this process is poorly understood in the OSE, in other tissues wound repair is known to be under the control of the local microenvironment and different growth factors such as the WNT signaling pathway. Among WNT family members, WNT4 and WNT5a are expressed in the OSE and are critical for the ovulatory process. The objective of this study was to determine the potential roles of WNT4 and WNT5a in regulating the OSE layer. Using primary cultures of mouse OSE cells, we found WNT5a, but not WNT4, promotes EMT through a non-canonical Ca2+-dependent pathway, up-regulating the expression of Vimentin and CD44, enhancing cell migration, and inhibiting the CTNNB1 pathway and proliferation. We conclude that WNT5a is a stimulator of the EMT in OSE cells, and acts by suppressing canonical WNT signaling activity and inducing the non-canonical Ca2+ pathway.

Frizzled related protein deficiency impairs muscle strength, gait and calpain 3 levels

Background

Limb-girdle muscular dystrophy recessive 1 calpain3-related (LGMDR1), previously known as LGMD2A, is a disease caused by mutations in the CAPN3 gene. It is characterized by progressive weakness and muscle degeneration. Frizzled related protein (FRZB), upregulated in LGMDR1, was identified as a key regulator of the crosstalk between Wnt and integrin signalling pathways. FRZB gene silencing showed a recovery in the expression of some of the costamere protein levels in myotubes.

Results

Here, we performed a comprehensive characterization of Frzb^−/− mice muscles to study the absence of Frzb in skeletal muscle and eventual links with the molecular characteristics of LGMDR1 patient muscles. Frzb^−/− mice showed reduced muscle size and strength. Gait analysis showed that Frzb^−/− mice moved more slowly but no impaired regeneration capacity was observed after muscle injury. Additionally, Frzb^−/− mice muscle showed an increased number of mesoangioblasts. Lack of Frzb gene in Frzb^−/− mice and its increased expression in LGMDR1 patients, showed contrary regulation of Rora, Slc16a1, Tfrc and Capn3 genes. The reciprocal regulation of Frzb and Capn3 genes further supports this axis as a potential target for LGMDR1 patients.

Conclusions

Our data confirm a role for Frzb in the regulation of Rora, Slc16a1, Tfrc, and Capn3 genes in muscle cells. In vivo, reduced muscle strength and gait in the Frzb^−/− mice are intriguing features. The reciprocal relationship between FRZB and CAPN3 further supports a key role for this axis in patients with LGMDR1.

Distinct functions and prognostic values of RORs in gastric cancer

Retinoic acid receptor-related orphan receptors (RORs) are frequently abnormally expressed in several human malignancies, including gastric cancer (GC). RORs are involved in the development and progression of GC through Wnt signaling pathway receptors and other common receptors. However, the prognostic roles of individual RORs in patients with GC remain elusive. We accessed the prognostic roles of three RORs (RORα, RORβ, and RORγ) through "The Kaplan-Meier plotter" (KM plotter) database in patients with GC. For all patients with GC who were followed for 20 years, the low mRNA expression of all three RORs showed a significant correlation with better outcomes. We further accessed the prognostic value of individual RORs in different clinical pathological features including Lauren classification, clinical stages, pathological grades, HER2 status, and different treatments methods. The RORs demonstrated critical prognostic roles in GC. Expressions of RORs were higher in GC tissues when compared with normal gastric tissues. Moreover, knockdown of RORs significantly inhibited cell proliferation and migration, suggesting an oncogenic role of RORs in human GC. These findings suggest potential roles of RORs as biomarkers for GC prognosis and as oncogenes in GC.

Isoform-Specific Lysine Methylation of RORα2 by SETD7 Is Required for Association of the TIP60 Coactivator Complex in Prostate Cancer Progression

The retinoid acid-related orphan receptor α (RORα), a member of the orphan nuclear receptor superfamily, functions as an unknown ligand-dependent transcription factor. RORα was shown to regulate a broad array of physiological processes such as Purkinje cell development in the cerebellum, circadian rhythm, lipid and bone metabolism, inhibition of inflammation, and anti-apoptosis. The human RORα gene encodes at least four distinct isoforms (RORα1, -2, -3, -4), which differ only in their N-terminal domain (NTD). Two isoforms, RORα2 and 3, are not expressed in mice, whereas RORα1 and 4 are expressed both in mice and humans. In the present study, we identified the specific NTD of RORα2 that enhances prostate tumor progression and proliferation via lysine methylation-mediated recruitment of coactivator complex pontin/Tip60. Upregulation of the RORα2 isoform in prostate cancers putatively promotes tumor formation and progression. Furthermore, binding between coactivator complex and RORα2 is increased by lysine methylation of RORα2 because methylation permits subsequent interaction with binding partners. This methylation-dependent activation is performed by SET domain containing 7 (SETD7) methyltransferase, inducing the oncogenic potential of RORα2. Thus, post-translational lysine methylation of RORα2 modulates oncogenic function of RORα2 in prostate cancer. Exploration of the post-translational modifications of RORα2 provides new avenues for the development of tumor-suppressive therapeutic agents through modulating the human isoform-specific tumorigenic role of RORα2.

Hepatic stellate cells promote the progression of hepatocellular carcinoma through microRNA-1246-RORα-Wnt/β-Catenin axis

Hepatic stellate cells (HSCs) play vital roles in tumorigenesis and progression of hepatocellular carcinoma (HCC). However, there remains a lack of high-throughput studies on gene expression alterations in HCC cells in response to direct interactions with HSCs. In this study, we established a direct co-culture model of HSCs and HCC cells. We found that the expression of a set of miRNAs, most notably miR-1246, was triggered by HSCs. RORα was confirmed as the target gene of miR-1246. Either overexpression of miR-1246 or knockdown of RORα enhanced the proliferation, invasiveness, and metastatic capability of HCC both in vitro and in vivo, through Wnt/β-catenin pathway activation and promotion of epithelial-mesenchymal transition (EMT). Moreover, upregulation of miR-1246 and repression of RORα were prominent features of aggressive clinical HCC. The miR-1246-RORα-Wnt/β-catenin axis is a novel pathway through which HSCs accelerate HCC progression.

ROR-α-1 inhibits the proliferation, invasion, and migration of hepatocellular carcinoma MHCC97H via downregulation of chemokine CXCL5

Hepatocarcinogenesis is a complicated process that is affected by a variety of microenvironmental factors, such as secretory chemokines and cell-extracellular matrix (ECM). Retinoic acid receptor-related orphan receptor (ROR)-α has been shown to attenuate tumor invasiveness by inducing suppressive cell microenvironment, and its low expression was associated with a worse prognosis in HCC patients. In the present study, we attempted to investigate the role and mechanism of the dominant transcript of ROR-α, ROR-α-1, in HCC development and progression. Among the four transcripts (ROR-α-1/-2/-3/-4), overexpression of ROR-α-1 dramatically suppressed the capacity of MHCC97H cells to proliferate, migrate and invade. We analyzed the differentially expressed genes in ROR-α-1-overexpressed and non-overexpressed MHCC97H cells, performed Gene Ontology (GO) enrichment analysis on these differentially-expressed genes, and found out that factors involved in the tumor microenvironment and ECM are related to the anti-tumor effects of ROR-α-1. Among these factors, chemokine CXCL5 was significantly downregulated by ROR-α-1 overexpression. Overexpression of ROR-α-1 remarkably inhibited the capacity of HCC cells to proliferate, migrate, invade, and downregulated the protein levels of β-catenin, c-Myc, Cyclin D1, and N-cadherin, suggesting the tumor-suppressive role of ROR-α-1 in MHCC97H cells. Moreover, overexpression of CXCL5 dramatically attenuated the suppressive effects of cell proliferation, migration and invasion induced by ROR-α-1 overexpression in MHCC97H, suggesting that ROR-α-1 exerts its anti-tumor effects via downregulating CXCL5. In conclusion, we demonstrate the tumor-suppressive role of ROR-α-1 in MHCC97H cells and that ROR-α-1 might play a tumor-suppressive role via regulation of chemokine CXCL5.

RORα Suppresses Epithelial-to-Mesenchymal Transition and Invasion in Human Gastric Cancer Cells via the Wnt/β-Catenin Pathway

Retinoid-related orphan receptor alpha (RORα) is involved in tumor development. However, the mechanisms underlying RORα inhibiting epithelial-to-mesenchymal transition (EMT) and invasion are poorly understood in gastric cancer (GC). This study revealed that the decreased expression of RORα is associated with GC development, progression, and prognosis. RORα suppressed cell proliferation, EMT, and invasion in GC cells through inhibition of the Wnt/β-catenin pathway. RORα overexpression resulted in the decreased Wnt1 expression and the increased RORα interaction with β-catenin, which could lead to the decreased intranuclear β-catenin and p-β-catenin levels, concomitant with downregulated T-cell factor-4 (TCF-4) expression and the promoter activity of c-Myc. The inhibition of Wnt/β-catenin pathway was coupled with the reduced expression of Axin, c-Myc, and c-Jun. RORα downregulated vimentin and Snail and upregulated E-cadherin protein levels in vitro and in vivo. Inversely, knockdown of RORα attenuated its inhibitory effects on Wnt/β-catenin pathway and its downstream gene expression, facilitating cell proliferation, EMT, migration, and invasion in GC cells. Therefore, RORα could play a crucial role in repressing GC cell proliferation, EMT, and invasion via downregulating Wnt/β-catenin pathway.

The RNA-binding protein SORBS2 suppresses hepatocellular carcinoma tumourigenesis and metastasis by stabilizing RORA mRNA

BACKGROUND

Numerous studies have revealed that dysregulation of RNA-binding protein (RBP) expression is causally linked with human cancer tumourigenesis. However, the detailed biological effect and underlying mechanisms of most RBPs remain unclear.

METHODS

Expression of sorbin and SH3 domain-containing 2 (SORBS2) in hepatocellular carcinoma (HCC) was detected by qRT-PCR, immunohistochemistry assay and Western blot assay. Proliferation, migration, invasion and cell cycle progression of HCC cells were measured by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, colony-forming assay, Transwell assay and flow cytometry assay respectively. A xenograft model and metastatic model were established to evaluate the proliferation and metastasis of HCC cells in vivo. Western blot assays were performed to assess the expression of epithelial-mesenchymal transition markers. Luciferase reporter assay, RNA immunoprecipitation and pull-down assay elucidated the effect of SORBS2 on one of its downstream genes.

RESULTS

The expression of SORBS2 was significantly decreased in HCC and was associated with metastasis, advanced TNM clinical stage and poor clinical outcome of HCC patients. Furthermore, our results suggested that SORBS2 inhibited HCC cell proliferation, invasion, migration and EMT both in vivo and in vitro. Mechanistically, we revealed that retinoic acid receptor-related orphan receptor (RORA) was a major target of SORBS2 and was critical to sustaining the antitumour effect of SORBS2 on HCC cells. SORBS2 reduced RORA mRNA degradation by directly binding to the 3'UTR of RORA mRNA.

CONCLUSIONS

In this study, we found for the first time that SORBS2 contributed to the suppression of HCC tumourigenesis and metastasis via post-transcriptional regulation of RORA expression as an RBP.