Retinoic acid receptor-related receptor alpha (RORalpha) is a prognostic marker for hepatocellular carcinoma

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.

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.

RORα inhibits gastric cancer proliferation through attenuating G6PD and PFKFB3 induced glycolytic activity

BACKGROUND

Glycolysis is critical for harvesting abundant energy to maintain the tumor microenvironment in malignant tumors. Retinoic acid-related orphan receptor α (RORα) has been identified as a circadian gene. However, the association of glycolysis with RORα in regulating gastric cancer (GC) proliferation remains poorly understood.

METHODS

Bioinformatic analysis and retrospective study were utilized to explore the role of RORα in cell cycle and glycolysis in GC. The mechanisms were performed in vitro and in vivo including colony formation, Cell Counting Kit-8 (CCK-8), Epithelial- mesenchymal transition (EMT) and subcutaneous tumors of mice model assays. The key drives between RORα and glycolysis were verified through western blot and chip assays. Moreover, we constructed models of high proliferation and high glucose environments to verify a negative feedback and chemoresistance through a series of functional experiments in vitro and in vivo.

RESULTS

RORα was found to be involved in the cell cycle and glycolysis through a gene set enrichment analysis (GSEA) algorithm. GC patients with low RORα expression were not only associated with high circulating tumor cells (CTC) and high vascular endothelial growth factor (VEGF) levels. However, it also presented a positive correlation with the standard uptake value (SUV) level. Moreover, the SUVmax levels showed a positive linear relation with CTC and VEGF levels. In addition, RORα expression levels were associated with glucose 6 phosphate dehydrogenase (G6PD) and phosphofructokinase-2/fructose-2,6-bisphosphatase (PFKFB3) expression levels, and GC patients with low RORα and high G6PD or low RORα and high PFKFB3 expression patterns had poorest disease-free survival (DFS). Functionally, RORα deletion promoted GC proliferation and drove glycolysis in vitro and in vivo. These phenomena were reversed by the RORα activator SR1078. Moreover, RORα deletion promoted GC proliferation through attenuating G6PD and PFKFB3 induced glycolytic activity in vitro and in vivo. Mechanistically, RORα was recruited to the G6PD and PFKFB3 promoters to modulate their transcription. Next, high proliferation and high glucose inhibited RORα expression, which indicated that negative feedback exists in GC. Moreover, RORα deletion improved fluorouracil chemoresistance through inhibition of glucose uptake.

CONCLUSION

RORα might be a novel biomarker and therapeutic target for GC through attenuating glycolysis.

Gastric Carcinoma with low ROR alpha, low E- Cadherin and High LAPTM4B Immunohistochemical Profile; is associated with unfavorable prognosis in Egyptian patients

In view of multiplicity of carcinogenic pathways of gastric carcinoma (GC), poor survival and chemotherapy resistance, more analysis of these pathways is required for prediction of prognosis and developing new therapeutic targets. Knocking down of RORα; induces tumor cell proliferation and epithelial-mesenchymal transition (EMT). LAPTM4B has been suggested to be associated with EMT which promote tumor invasion. This work aimed to investigate prognostic role of RORα, LAPTM4B, and E-Cadherin expression in GC. This retrospective immunohistochemical study assesses the expression of RORα, LAPTM4B, and E-Cadherin in 73 primary gastric carcinomas. Low RORα and high LAPTM4B expression in GC cases were associated with unfavorable prognostic factors such as positive lymph nodes, and high tumor budding. E-Cadherin heterogeneous staining was associated with poor prognostic criteria, such as diffuse type GC and high tumor budding. Low RORα, high LAPTM4B, and heterogeneous E-Cadherin were the most common immunohistochemical profile in GC cases. Low RORα expression showed poor prognostic impact on overall patient survival. In conclusion, RORα and LAPTM4B may have crucial role in GC aggressiveness. The predominance of low RORα, high LAPTM4B, and heterogeneous or negative E-Cadherin immunohistochemical profile in GC cases with unfavorable pathological parameters suggested that this profile may predict tumor behavior.

Circadian stabilization loop: the regulatory hub and therapeutic target promoting circadian resilience and physiological health

The circadian clock is a fundamental biological mechanism that orchestrates essential cellular and physiological processes to optimize fitness and health. The basic functional unit is the cell-autonomous oscillator, consisting of intersecting negative feedback loops. Whereas the core loop is primarily responsible for rhythm generation, auxiliary loops, most notably the secondary or stabilization loop, play pivotal roles to confer temporal precision and molecular robustness. The stabilization loop contains opposing nuclear receptor subfamilies REV-ERBs and retinoic acid receptor-related orphan receptors (RORs), competing to modulate rhythmic expression of the basic helix-loop-helix ARNT like 1 ( Bmal1) genes in the core loop as well as other clock-controlled genes. Therefore, REV-ERBs and RORs are strategically located to interface the oscillator and the global transcriptomic network, promoting cellular homeostasis and physiological fitness throughout lifespan. Disruption of REV-ERB and ROR functions has been linked with diseases and aging, and pharmacological manipulation of these factors has shown promise in various mouse disease models. Nobiletin is a natural compound that directly binds to and activates RORα/γ, modulating circadian rhythms, and shows robust in vivo efficacies to combat clock-associated pathophysiologies and age-related decline. Results from several studies demonstrate an inverse relation between nobiletin efficacy and clock functional state, where nobiletin elicits little effect in young and healthy mice with growing efficacy as the clock is perturbed by environmental and genetic challenges. This mode of action is consistent with the function of the stabilization loop to promote circadian and physiological resilience. Future studies should further investigate the function and mechanism of REV-ERBs and RORs, and test strategies targeting these factors against disease and aging.

Circadian stabilization loop: the regulatory hub and therapeutic target promoting circadian resilience and physiological health

The circadian clock is a fundamental biological mechanism that orchestrates essential cellular and physiological processes to optimize fitness and health. The basic functional unit is the cell-autonomous oscillator, consisting of intersecting negative feedback loops. Whereas the core loop is primarily responsible for rhythm generation, auxiliary loops, most notably the secondary or stabilization loop, play pivotal roles to confer temporal precision and molecular robustness. The stabilization loop contains opposing nuclear receptor subfamilies REV-ERBs and retinoic acid receptor-related orphan receptors (RORs), competing to modulate rhythmic expression of the basic helix-loop-helix ARNT like 1 ( Bmal1) genes in the core loop as well as other clock-controlled genes. Therefore, REV-ERBs and RORs are strategically located to interface the oscillator and the global transcriptomic network, promoting cellular homeostasis and physiological fitness throughout lifespan. Disruption of REV-ERB and ROR functions has been linked with diseases and aging, and pharmacological manipulation of these factors has shown promise in various mouse disease models. Nobiletin is a natural compound that directly binds to and activates RORα/γ, modulating circadian rhythms, and shows robust in vivo efficacies to combat clock-associated pathophysiologies and age-related decline. Results from several studies demonstrate an inverse relation between nobiletin efficacy and clock functional state, where nobiletin elicits little effect in young and healthy mice with growing efficacy as the clock is perturbed by environmental and genetic challenges. This mode of action is consistent with the function of the stabilization loop to promote circadian and physiological resilience. Future studies should further investigate the function and mechanism of REV-ERBs and RORs, and test strategies targeting these factors against disease and aging.

Gastric Carcinoma with low ROR alpha, low E- Cadherin and High LAPTM4B Immunohistochemical Profile; is associated with poor prognosis in Egyptian patients.. [DOI: 10.21203/rs.3.rs-2123133/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background Gastric carcinoma (GC) is the tenth most prevalent cancer in both sexes in Egypt. Many pathways have been investigated regarding pathogenesis of GC, including epithelial-mesenchymal transition (EMT) pathway. In view of multiplicity of carcinogenic pathways, poor survival and chemotherapy resistance detected in GC patients, more analysis of these pathways is required for better molecular selection of patients, prediction of prognosis and developing new therapeutic targets. Down-regulation of E-Cadherin is an important EMT stage. RORα is a tumor suppressor gene, expressed in normal epithelial tissues and reduced in a variety of human cancers. Knocking down of RORα; increase cell proliferation, EMT, migration, and invasion. LAPTM4B is a protooncogene and it has been suggested to be strictly associated with EMT induction. Therefore, this work aims to investigate the role of RORα, LAPTM4B and E-Cadherin and its relationship to prognosis of GC. Methods This is a retrospective study where the standard immunohistochemical technique was done to assess the expression of RORα, LAPTM4B and E-Cadherin in 167 cases of chronic gastritis (control group) and 73 primary gastric carcinomas (51 of them have available adjacent non tumor tissue). Results Low RORα and high LAPTM4B expression in GC cases were associated with unfavorable prognostic factors such as positive lymph nodes, and high tumor budding. E-Cadherin Heterogeneous staining was associated with poor prognostic pathological criteria, such as diffuse type GC and high tumor budding. In GC, there was significant co parallel correlation between RORα and E-Cadherin expression while LAPTM4B showed inverse correlation with E-Cadherin expression. Low RORα, high LAPTM4B, and negative or heterogeneous E-Cadherin were the most common immunohistochemical profile in GC cases. Low RORα expression showed poor prognostic impact on overall patient survival. Conclusions Low RORα H-score and increased expression of LAPTM4B were significantly associated with unfavorable prognostic parameters of GC which may indicate their crucial role in tumor aggressiveness. The predominance of low RORα, high LAPTM4B and heterogeneous or negative E-Cadherin immunohistochemical profile in GC cases with unfavorable pathological parameters suggested that this profile may predict tumor behavior and this profile could be linked to EMT molecular subtype of GC

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.

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.

Identification of TIMELESS and RORA as key clock molecules of non-small cell lung cancer and the comprehensive analysis

Background

The incidence rate of non-small cell lung cancer (NSCLC) has been increasing worldwide, and the correlation of circadian rhythm disruption with a raised risk of cancer and worse prognosis has been shown by accumulating evidences recently. On the other hand, drug resistance and the impact of tumor heterogeneity have been inevitable in NSCLC therapy. These both lead to an urgent need to identify more useful prognostic and predictive markers for NSCLC diagnosis and treatment, especially on the aspect of circadian clock genes.

Methods

The expression of the main clock genes in cancer was probed with TIMER and Oncomine databases. The prognostic value of key clock genes was probed systematically with the Kaplan–Meier estimate and Cox regression on samples from TCGA database. RT-qPCR was performed on patient tissue samples to further validate the results from databases. The functional enrichment analysis was performed using the “ClusterProfiler” R package, and the correlation of key clock genes with tumor mutation burden, immune checkpoint, and immune infiltration levels were also assessed using multiple algorithms including TIDE, TIMER2.0, and XCELL.

Results

TIMELESS was significantly upregulated in lung tissue of clinical lung cancer patients as well as TCGA and Oncomine databases, while RORA was downregulated. Multivariate Cox regression analysis indicated that TIMELESS (P = 0.004, HR = 1.21 [1.06, 1.38]) and RORA (P = 0.047, HR = 0.868 [0.755, 0.998]) has a significant correlation with overall survival in NSCLC. Genes related to TIMELESS were enriched in the cell cycle and immune system, and the function of RORA was mainly focused on oncogenic signaling pathways or glycosylation and protein activation. Also, TIMELESS was positively correlated with tumor mutation burden while RORA was negatively correlated with it. TIMELESS and RORA were also significantly correlated with immune checkpoint and immune infiltration levels in NSCLC. Additionally, TIMELESS showed a significant positive relationship with lipid metabolism.

Conclusions

TIMELESS and RORA were identified as key clock genes in NSCLC, and were independent prognostic factors for overall survival in NSCLC. The function of them were assessed in many aspects, indicating the strong potential of the two genes to serve as biomarkers for NSCLC progression and prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09203-1.

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.

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.

Is Vitamin D Deficiency Related to Increased Cancer Risk in Patients with Type 2 Diabetes Mellitus?

There is mounting evidence that type 2 diabetes mellitus (T2DM) is related with increased risk for the development of cancer. Apart from shared common risk factors typical for both diseases, diabetes driven factors including hyperinsulinemia, insulin resistance, hyperglycemia and low grade chronic inflammation are of great importance. Recently, vitamin D deficiency was reported to be associated with the pathogenesis of numerous diseases, including T2DM and cancer. However, little is known whether vitamin D deficiency may be responsible for elevated cancer risk development in T2DM patients. Therefore, the aim of the current review is to identify the molecular mechanisms by which vitamin D deficiency may contribute to cancer development in T2DM patients. Vitamin D via alleviation of insulin resistance, hyperglycemia, oxidative stress and inflammation reduces diabetes driven cancer risk factors. Moreover, vitamin D strengthens the DNA repair process, and regulates apoptosis and autophagy of cancer cells as well as signaling pathways involved in tumorigenesis i.e., tumor growth factor β (TGFβ), insulin-like growth factor (IGF) and Wnt-β-Cathenin. It should also be underlined that many types of cancer cells present alterations in vitamin D metabolism and action as a result of Vitamin D Receptor (VDR) and CYP27B1 expression dysregulation. Although, numerous studies revealed that adequate vitamin D concentration prevents or delays T2DM and cancer development, little is known how the vitamin affects cancer risk among T2DM patients. There is a pressing need for randomized clinical trials to clarify whether vitamin D deficiency may be a factor responsible for increased risk of cancer in T2DM patients, and whether the use of the vitamin by patients with diabetes and cancer may improve cancer prognosis and metabolic control of diabetes.

Integrative Pan-Cancer Analysis Reveals Decreased Melatonergic Gene Expression in Carcinogenesis and RORA as a Prognostic Marker for Hepatocellular Carcinoma

Background

Melatonin has been shown to play a protective role in the development and progression of cancer. However, the relationship between alterations in the melatonergic microenvironment and cancer development has remained unclear.

Methods

We performed a comprehensive investigation on 12 melatonergic genes and their relevance to cancer occurrence, progression and survival by integrating multi-omics data from microarray analysis and RNA sequencing across 11 cancer types. Specifically, the 12 melatonergic genes that we investigated, which reflect the melatonergic microenvironment, included three membrane receptor genes, three nuclear receptor genes, two intracellular receptor genes, one synthetic gene, and three metabolic genes.

Results

Widely coherent underexpression of nuclear receptor genes, intracellular receptor genes, and metabolic genes was observed in cancerous samples from multiple cancer types compared to that in normal samples. Furthermore, genomic and/or epigenetic alterations partially contributed to these abnormal expression patterns in cancerous samples. Moreover, the majority of melatonergic genes had significant prognostic effects in predicting overall survival. Nevertheless, few corresponding alterations in expression were observed during cancer progression, and alterations in expression patterns varied greatly across cancer types. However, the association of melatonergic genes with one specific cancer type, hepatocellular carcinoma, identified RORA as a tumor suppressor and a prognostic marker for patients with hepatocellular carcinoma.

Conclusions

Overall, our study revealed decreased melatonergic gene expression in various cancers, which may help to better elucidate the relationship between melatonin and cancer development. Taken together, our findings highlight the potential prognostic significance of melatonergic genes in various cancers.

MiR-652 serves as a prognostic biomarker in gastric cancer and promotes tumor proliferation, migration, and invasion via targeting RORA

PURPOSE

MicroRNAs (miRNAs) have been reported to be involved in tumorigenesis. The aim of this study was to investigate the functional role and prognostic value of miR-652 in gastric cancer (GC).

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to determine the expression levels of miR-652 in human GC tissue samples and GC cell lines. The Kaplan-Meier survival curves and Cox regression analysis were performed to measure the prognostic value of miR-652 in GC. The tumor cell proliferation capacity was estimated by MTT assay, and cell migration and invasion were assessed by Transwell assays. The luciferase reporter assay was performed to confirm the target gene of miR-652.

RESULTS

MiR-652 was significantly elevated in GC tissues and cell lines (all P< 0.001). And the expression level of miR-652 was significantly associated with TNM stage and lymph node metastasis (all P< 0.05). GC patients with high expression of miR-652 had a shorter overall survival rate than those with low miR-652 expression (log-rank P< 0.001). The miR-652 and TNM stage were proven to be independent prognostic predictors for the GC patients. Overexpressing miR-652 could enhance cell proliferation, migration and invasion (all P< 0.01). RORA was proved to be the target gene of miR-652.

CONCLUSION

MiR-652 functions as an oncogene in GC and promotes tumor progression via targeting RORA. MiR-652 might be a novel predictive marker for the poor prognosis of GC patients.

MiR-18a-downregulated RORA inhibits the proliferation and tumorigenesis of glioma using the TNF-α-mediated NF-κB signaling pathway

BACKGROUND

Glioma has a poor prognosis, and is the most common primary and lethal primary malignant tumor in the central nervous system. Retinoic acid receptor-related orphan receptor A (RORA) is a member of the ROR subfamily of orphan receptors and plays an anti-tumor role in several cancers.

METHODS

A cell viability assay, the Edu assay, neurosphere formation assay, and xenograft experiments were used to detect the proliferative abilities of glioma cell line, glioma stem cells (GSCs). Western blotting, ELISAs, and luciferase reporter assays were used to detect the presence of possible microRNAs.

FINDINGS

Our study found for the first time that RORA was expressed at low levels in gliomas, and was associated with a good prognosis. RORA overexpression inhibited the proliferation and tumorigenesis of glioma cell lines and GSCs via inhibiting the TNF-α mediated NF-κB signaling pathway. In addition, microRNA-18a had a promoting effect on gliomas, and was the possible reason for low RORA expression in gliomas.

INTERPRETATION

RORA may be a promising therapeutic target in the treatment of gliomas.

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.

microRNA-messenger RNA regulatory network of esophageal squamous cell carcinoma and the identification of miR-1 as a biomarker of patient survival

Emerging evidence indicates that microRNAs (miRNAs) play an important role in tumor carcinogenesis and progression by targeting gene expression. The goal of this study was to comprehensively analyze the vital functional miRNAs and their target genes in esophageal squamous cell carcinoma (ESCC) and to explore the clinical significance and mechanisms of miR-1 in ESCC. First, the miRNA and messenger RNA (mRNA) expression profiles of ESCC were determined with microarray technology. Using an integrated analysis of miRNAs and their target genes with multistep bioinformatics methods, the miRNA-mRNA regulatory network in ESCC was constructed. Next, miR-1 expression in 292 ESCC patients and its relationship with clinicopathological features and prognosis were detected by in situ hybridization. Furthermore, the biological functions of miR-1 were determined with in vitro and in vivo functional experiments. Finally, real-time quantitative reverse transcription polymerase chain reaction, Western blot analysis, and luciferase reporter assays were performed to verify the target genes of miR-1. In this study, 67 miRNAs and 2992 genes were significantly differentially expressed in ESCC tissues compared with their expression in adjacent normal tissues, and an miRNA-mRNA regulatory network comprising 59 miRNAs and 162 target mRNAs was identified. Low miR-1 expression was correlated with pathological T stage, lymph node metastasis, vessel invasion, and poor clinical outcome. miR-1 suppressed ESCC cell proliferation and invasion and promoted ESCC cell apoptosis. Fibronectin 1 (FN1) was verified as a direct target of miR-1. Taken together, the present results suggest that miR-1 may be a valuable prognostic predictor for ESCC, and the miR-1/FN1 axis may be a therapeutic target.

Circadian clock pathway genes associated with colorectal cancer risk and prognosis

Circadian clock genes influence biological processes and may be involved in tumorigenesis. We systematically evaluated genetic variants in the circadian clock pathway genes associated with colorectal cancer risk and survival. We evaluated the association of 119 single nucleotide polymorphisms (SNPs) in 27 circadian clock pathway genes with the risk of colorectal cancer in a case-control study (1150 cases and 1342 controls). The false discovery rate (FDR) method was applied to correct for multiple comparisons. Gene-based analysis was performed by the sequence kernel association test (SKAT). Cox proportional hazards regression was used to calculate the effects of SNPs on the overall survival of patients. We identified that compared to those with the G allele, individuals with the rs76436997 A allele in RORA had a significant 1.33-fold increased risk of colorectal cancer (P = 3.83 × 10^- 4). Specifically, the GA/AA genotypes were related to an enhanced risk of colorectal cancer compared with that associated with the GG genotype, which was more common in patients with well and moderately differentiated tumors and Dukes A/B stages. The SNP rs76436997 significantly increased the overall survival time of colorectal cancer patients (P = 0.044). Furthermore, RNA-seq data showed that the mRNA levels of RORA were significantly lower in colorectal tumors than the paired normal tissues. Gene-based analysis revealed a significant association between RORA and colorectal cancer risk. These findings highlight the important roles of genetic variations in circadian clock pathway genes play in colorectal cancer risk and suggest that RORA is potentially related to colorectal carcinogenesis.

RORα and RORγ expression inversely correlates with human melanoma progression

The retinoic acid-related orphan receptors (RORs) regulate several physiological and pathological processes, including immune functions, development and cancer. To study the potential role of RORs in melanoma progression, we analysed RORα and RORγ expression in nevi and primary melanomas and non-lesional skin and metastases in relation to melanoma clinico-pathomorphological features. The expression of RORα and RORγ was lower in melanomas than in nevi and decreased during melanoma progression, with lowest levels found in primary melanomas at stages III and IV and in melanoma metastases. Their expression correlated with pathomorphological pTNM parameters being low in aggressive tumors and being high in tumors showing histological markers of good prognosis. Higher nuclear levels of RORα and RORγ and of cytoplasmic RORγ correlated with significantly longer overall and disease free survival time. Highly pigmented melanomas showed significantly lower level of nuclear RORs. This study shows that human melanoma development and aggressiveness is associated with decreased expression of RORα and RORγ, suggesting that RORs could be important in melanoma progression and host responses against the tumor. Furthermore, it suggests that RORα and RORγ might constitute a novel druggable target in anti-melanoma management using tumor suppressor gene therapy restoring their normal functions.

Exploring vitamin D metabolism and function in cancer

Vitamin D, traditionally known as an essential nutrient, is a precursor of a potent steroid hormone that regulates a broad spectrum of physiological processes. In addition to its classical roles in bone metabolism, epidemiological, preclinical, and cellular research during the last decades, it revealed that vitamin D may play a key role in the prevention and treatment of many extra-skeletal diseases such as cancer. Vitamin D, as a prohormone, undergoes two-step metabolism in liver and kidney to produce a biologically active metabolite, calcitriol, which binds to the vitamin D receptor (VDR) for the regulation of expression of diverse genes. In addition, recent studies have revealed that vitamin D can also be metabolized and activated through a CYP11A1-driven non-canonical metabolic pathway. Numerous anticancer properties of vitamin D have been proposed, with diverse effects on cancer development and progression. However, accumulating data suggest that the metabolism and functions of vitamin D are dysregulated in many types of cancer, conferring resistance to the antitumorigenic effects of vitamin D and thereby contributing to the development and progression of cancer. Thus, understanding dysregulated vitamin D metabolism and function in cancer will be critical for the development of promising new strategies for successful vitamin D-based cancer therapy.

Nuclear receptor retinoid-related orphan receptor alpha promotes apoptosis but is reduced in human gastric cancer

Retinoid-related orphan receptor α (RORα) is a nuclear receptor, which regulates inflammation and immune responses, lipid metabolism and circadian rhythm. Although RORα suppresses breast tumor invasion, it is unknown whether RORα is dysregulated in gastric cancer leading to cellular survival. Therefore, we hypothesize that RORα is dysfunctional in gastric carcinoma and this causes decreased apoptosis in gastric cancer cells. To test this hypothesis, we employed human gastric cancer tissues with different stages to determine RORα expression, as well as in vitro human gastric cancer cells to determine how RORα is reduced during apoptosis. We found that the expression of RORα was reduced in gastric tissues with cancer, and this correlated with increased TNM stages. The mechanisms underlying RORα reduction is due to the reduced activation of AMP-activated protein kinase (AMPK), as a selective AMPK activator AICAR increased RORα activation and level in human gastric cancer cells. Furthermore, AICAR treatment increased RORα recruitment on the promoters of tumor suppressor genes (i.e., FBXM7, SEMA3F and p21) leading to apoptosis in human gastric cancer cells. Taken together, RORα reduction occurs in gastric cancer leading to the survival of tumor cells, which is attenuated by AMPK. Therefore, both RORα and AMPK are potential targets for the intervention and therapy in gastric carcinoma.

Vitamin D signaling and melanoma: role of vitamin D and its receptors in melanoma progression and management

Ultraviolet B (UVB), in addition to having carcinogenic activity, is required for the production of vitamin D3 (D3) in the skin which supplies >90% of the body's requirement. Vitamin D is activated through hydroxylation by 25-hydroxylases (CYP2R1 or CYP27A1) and 1α-hydroxylase (CYP27B1) to produce 1,25(OH)₂D3, or through the action of CYP11A1 to produce mono-di- and trihydroxy-D3 products that can be further modified by CYP27B1, CYP27A1, and CYP24A1. The active forms of D3, in addition to regulating calcium metabolism, exert pleiotropic activities, which include anticarcinogenic and anti-melanoma effects in experimental models, with photoprotection against UVB-induced damage. These diverse effects are mediated through an interaction with the vitamin D receptor (VDR) and/or as most recently demonstrated through action on retinoic acid orphan receptors (ROR)α and RORγ. With respect to melanoma, low levels of 25(OH)D are associated with thicker tumors and reduced patient survival. Furthermore, single-nucleotide polymorphisms of VDR and the vitamin D-binding protein (VDP) genes affect melanomagenesis or disease outcome. Clinicopathological analyses have shown positive correlation between low or undetectable expression of VDR and/or CYP27B1 in melanoma with tumor progression and shorter overall (OS) and disease-free survival (DFS) times. Paradoxically, this correlation was reversed for CYP24A1 (inactivating 24-hydroxylase), indicating that this enzyme, while inactivating 1,25(OH)₂D3, can activate other forms of D3 that are products of the non-canonical pathway initiated by CYP11A1. An inverse correlation has been found between the levels of RORα and RORγ expression and melanoma progression and disease outcome. Therefore, we propose that defects in vitamin D signaling including D3 activation/inactivation, and the expression and activity of the corresponding receptors, affect melanoma progression and the outcome of the disease. The existence of multiple bioactive forms of D3 and alternative receptors affecting the behavior of melanoma should be taken into consideration when applying vitamin D management for melanoma therapy.

Retinoic Acid-Related Orphan Receptors (RORs): Regulatory Functions in Immunity, Development, Circadian Rhythm, and Metabolism

In this overview, we provide an update on recent progress made in understanding the mechanisms of action, physiological functions, and roles in disease of retinoic acid related orphan receptors (RORs). We are particularly focusing on their roles in the regulation of adaptive and innate immunity, brain function, retinal development, cancer, glucose and lipid metabolism, circadian rhythm, metabolic and inflammatory diseases and neuropsychiatric disorders. We also summarize the current status of ROR agonists and inverse agonists, including their regulation of ROR activity and their therapeutic potential for management of various diseases in which RORs have been implicated.

Retinoic acid and cancer treatment

Retinoic acid which belongs to the retinoid class of chemical compounds is an important metabolite of vitamin A in diets. It is currently understood that retinoic acid plays important roles in cell development and differentiation as well as cancer treatment. Lung, prostate, breast, ovarian, bladder, oral, and skin cancers have been demonstrated to be suppressed by retinoic acid. Our results also show that low doses and high doses of retinoic acid may respectively cause cell cycle arrest and apoptosis of cancer cells. Also, the common cell cycle inhibiting protein, p27, and the new cell cycle regulator, Cdk5, are involved in retinoic acid’s effects. These results provide new evidence indicating that the molecular mechanisms of/in retinoic acid may control cancer cells’ fates. Since high doses of retinoic acid may lead to cytotoxicity, it is probably best utilized as a potential supplement in one’s daily diet to prevent or suppress cancer progression. In this review, we have collected numerous references demonstrating the findings of retinoic acid in melanoma, hepatoma, lung cancer, breast cancer, and prostate cancer. We hope these observations will shed light on the future investigation of retinoic acid in cancer prevention and therapy.