BACKGROUND: The regulator of calcineurin 1 (RCAN1) is expressed in multiple organs, including the heart, liver, brain, and kidney, and is closely linked to the pathogenesis of cardiovascular diseases, Down syndrome, and Alzheimer\'s disease. It is also implicated in the development of various organ tumors; however, its potential role in hepatocellular carcinoma (HCC) remains poorly understood. Therefore, the objective of this study was to investigate the potential mechanisms of RCAN1 in HCC through bioinformatics analysis.
METHODS: We conducted a joint analysis based on the NCBI and TCGA databases, integrating both bulk transcriptome and single-cell analyses to examine the principal biological functions of RCAN1 in HCC, as well as its roles related to phenotype, metabolism, and cell communication. Subsequently, an RCAN1-overexpressing cell line was established, and the effects of RCAN1 on tumor cells were validated through in vitro experiments. Moreover, we endeavored to identify potential related drugs using molecular docking and molecular dynamics simulations.
RESULTS: The expression of RCAN1 was found to be downregulated in 19 types of cancer tissues and upregulated in 11 types of cancer tissues. Higher levels of RCAN1 expression were associated with improved patient survival. RCAN1 was predominantly expressed in hepatocytes, macrophages, endothelial cells, and monocytes, and its high expression not only closely correlated with the distribution of cells related to the HCC phenotype but also with the distribution of HCC cells themselves. Additionally, Rcan1 may directly or indirectly participate in metabolic pathways such as alanine, aspartate, and glutamate metabolism, as well as butanoate metabolism, thereby influencing tumor cell proliferation and migration. In vitro experiments confirmed that RCAN1 overexpression promoted apoptosis while inhibiting proliferation and invasion of HCC cells. Through molecular docking of 1615 drugs, we screened brompheniramine as a potential target drug and verified our results by molecular dynamics.
CONCLUSIONS: In this study, we revealed the relationship between RCAN1 and HCC through bioinformatics methods, verified that RCAN1 can affect the progress of the disease through experiments, and finally identified potential therapeutic drugs through drug molecular docking and molecular dynamics.

BACKGROUND: Although metabolic disturbance is a characteristic of diabetic cardiomyopathy (DbCM), the detailed pathogenesis of DbCM remains unknown.
METHODS: We used a heart transplantation (HTx) cohort to explore the effect of diabetes mellitus on heart failure (HF) progression dependent of myocardium. Microscopic and ultramicroscopic pathology were used to depict the pathological features of human myocardium of DbCM. We performed targeted metabolomics to characterize the metabolic phenotype of human DbCM. Transcriptomics data were analyzed and weighted gene co-expression network analysis was performed to explore the potential upstream regulator for metabolic remodeling of DbCM. In vivo and in vitro experiments were further conducted to demonstrate the therapeutic effects and molecular mechanisms.
RESULTS: DbCM promoted the progression of HF and increased death or HF-rehospitalization after HTx. Lipid accumulation and mitochondrial fission were the obvious pathological features of DbCM myocardium. The concentrations of C14:0-CoA and C16:1-CoA were significantly increased in the myocardium, and they were positively correlated with the accelerated HF progression and RCAN1 expression in DbCM patients. Knockdown of RCAN1 improved cardiac dysfunction, lipid accumulation, and mitochondrial fission in db/db mice. In vitro studies showed that RCAN1 knockdown improved mitochondrial dysfunction in DbCM cardiomyocytes via the RCAN1-p-Drp1 Ser616 axis.
CONCLUSIONS: Diabetes is associated with faster progression of HF and causes poor prognosis after HTx, accompanied by metabolic remodeling in the myocardium. Accumulation of long chain acyl-CoA in the myocardium is the metabolic hallmark of human DbCM and is associated with more rapid disease progression for DbCM patients. Upregulation of RCAN1 in the myocardium is associated with the metabolic signatures of DbCM and RCAN1 is a potential therapeutic target for DbCM.

Background: This study aims to explore the role of RCAN1 in esophageal squamous cell carcinoma (ESCC) cells, determine the mRNA level of three RCAN1 isoforms in ESCC tissue, and evaluate the prognostic value of three RCAN1 isoforms. Methods: Colony-forming assay, Wound-healing assay and Transwell assay were used to evaluate the effect of RCAN1 on cell proliferation, migration and invasion. The mRNA expression of three RCAN1 isoforms was detected in paired tumor and normal tissues from 100 ESCC patients by real-time PCR. Kaplan-Meier survival curves and Cox proportional hazards model were used to evaluate the prognostic value of three RCAN1 isoforms. A nomogram was used to predict the probability of 2-year and 5-year overall survival (OS). Results: In vitro, knockdown of RCAN1 could promote ESCC cell proliferation, migration and invasion abilities. Compared to the paired normal tissues, RCAN1 isoform 1 (RCAN1.1, P=0.0027) and RCAN1 isoform 2 (RCAN1.2, P=0.0006) were significantly decreased in tumor tissues. The low expression of RCAN1.2 mRNA was associated with advanced stage (P=0.0176) and lymph node metastasis (LNM, P=0.0219). ESCC patients with low RCAN1.2 mRNA levels had shorter survival time compared to those with high RCAN1.2 levels (P=0.007). Multivariate COX analysis indicated that RCAN1.2 mRNA level was an independent prognostic indicator of OS of patients with ESCC (hazard ratio=0.5266, P=0.03554). The concordance index of nomogram to predict OS was 0.693 based on LNM, RCAN1.2, tumor stage and patients\' age. Conclusion: These findings show that RCAN1 gene play a role in preventing proliferation, migration, and invasive activity of ESCC cells. RCAN1.2 mRNA level is a novel prognostic marker in ESCC, targeting RCAN1.2 may provide a potential therapeutic approach in ESCC.

An inverse comorbidity has been observed between Down syndrome (DS) and solid tumors such as breast and lung cancers, and it is posited that the overexpression of genes within the Down Syndrome Critical Region (DSCR) of human chromosome 21 may account for this phenomenon. By analyzing publicly available DS mouse model transcriptomics data, we aimed to identify DSCR genes that may protect against human breast and lung cancers. Gene expression analyses with GEPIA2 and UALCAN showed that DSCR genes ETS2 and RCAN1 are significantly downregulated in breast and lung cancers, and their expression levels are higher in triple-negative compared to luminal and HER2-positive breast cancers. KM Plotter showed that low levels of ETS2 and RCAN1 are associated with poor survival outcomes in breast and lung cancers. Correlation analyses using OncoDB revealed that both genes are positively correlated in breast and lung cancers, suggesting that they are co-expressed and perhaps have complementary functions. Functional enrichment analyses using LinkedOmics also demonstrated that ETS2 and RCAN1 expression correlates with T-cell receptor signaling, regulation of immunological synapses, TGF-β signaling, EGFR signaling, IFN-γ signaling, TNF signaling, angiogenesis, and the p53 pathway. Altogether, ETS2 and RCAN1 may be essential for the development of breast and lung cancers. Experimental validation of their biological functions may further unravel their roles in DS and breast and lung cancers.

OBJECTIVE: Cardiac dysfunction and remodeling are serious complications of sepsis and are the main causes of death in sepsis. RCAN1 is a feedback regulator of cardiac hypertrophy. Here, we aim to investigate the role of RCAN1 in septic cardiomyopathy.
METHODS: Mice were randomly divided into control-WT, control-RCAN1-/-, LPS-induced WT and LPS-induced RCAN1-/- groups, some with Midiv-1 or KN93 treatment. The protein levels of RCAN1, p-ERK1/2, NFAT3, Drp1, p-Drp1, p-CaMKII in mouse hearts or cultured cardiomyocytes were determined by Western blotting. Myocardial function was assessed by echocardiography. Cardiac hypertrophy and fibrosis were detected by H&E and Masson\'s trichrome staining. Mitochondrial morphology was examined by transmission electron microscope. Serum level of LDH was detected by ELISA.
RESULTS: Our data show that RCAN1 was downregulated in septic mouse heart and LPS-induced cardiomyocytes. RCAN1-/- mice showed a severe impairment of cardiac function, and increased myocardial hypertrophy and fibrosis. The protein levels of NFAT3 and p-ERK1/2 were significantly increased in the heart tissues of RCAN1-/- mice. Further, RCAN1 deficiency aggravated sepsis-induced cardiac mitochondrial injury as indicated by increased ROS production, pathological fission and the loss of mitochondrial membrane potential. Inhibition of fission with Mdivi-1 reversed LPS-induced cardiac hypertrophy, fibrosis and dysfunction in RCAN1-/- mice. Moreover, RCAN1 depletion promoted mitochondrial translocation of CaMKII, which enhanced fission and septic hypertrophy, while inhibition of CaMKII with KN93 reduced excessive fission, improved LPS-mediated cardiac remodeling and dysfunction in RCAN1-/- mice.
CONCLUSIONS: Our finding demonstrated that RCAN1 deficiency aggravated mitochondrial injury and septic cardiomyopathy through activating CaMKII. RCAN1 serves as a novel therapeutic target for treatment of sepsis-related cardiac remodeling and dysfunction.

Periodontitis is a common oral disorder leading to tooth loss in both developed and developing regions of the world. This multifactorial condition is related to the abnormal activity of several molecular pathways, among them are oxytocin-related pathways. In this study, we enrolled 26 patients and 28 controls and assessed the expression of four oxytocin-related genes, namely, FOS, ITPR, RCAN1, and RGS2, in circulation and affected tissues of enrolled individuals using real-time PCR. Expression of FOS was downregulated in total periodontitis tissues compared with total control tissues [ratio of mean expression (RME) = 0.23, P-value = 0.03]. Expression of FOS was also lower in total blood samples of patients compared with total controls. Expression of ITPR was downregulated in total periodontitis tissues compared with total control tissues (RME = 0.16, P-value = 0.01). Moreover, the expression of ITPR was reduced in total blood samples of patients compared with controls (RME = 0.25, P-value = 0.03). Expression of RCAN1 was downregulated in total periodontitis tissues compared with total control tissues (RME = 0.17, P-value = 0.01). However, the expression of RCAN1 was not different in blood samples of affected vs. unaffected individuals. Finally, the expression of RGS2 was lower in total periodontitis tissues compared with total control tissues (RME = 0.24, P-value = 0.01) and in total blood samples of affected individuals compared with controls (RME = 0.42, P-value = 0.05). This study provides data about the association between expressions of oxytocin-related genes and the presence of periodontitis. Future studies are needed to unravel the mechanistic links and find the correlation between expressions of these genes and the pathological stage of periodontitis.

BACKGROUND: Schizophrenia is a neuropsychiatric disorder characterized by a variety of clinical manifestations. This disorder has a complex inheritance. Oxytocinegic system has been shown to be implicated in the pathophysiology of schizophrenia. This system can alter social cognition through direct interaction with dopaminergic signaling, facilitating brain-stimulation reward, reduction of defense mechanism and stress reactivity, and modulation of social information processing through enhancing the greatness of social incentives. Long non-coding RNAs (lncRNAs) can affect activity of oxytocinegic system, thus contributing in the etiology of this disorder.
METHODS: We designed the current study to appraise dysregulation of nine oxytocin-associated mRNAs and lncRNAs in the venous blood of patients with schizophrenia.
RESULTS: Expression of FOS was up-regulated in total patients compared with total control group (Expression ratio (95% CI)= 13.64 (5.46-34.05), adjusted P value<0.0001) and in female patients compared with female control group (Expression ratio (95% CI)=32.13 (5.81-176), adjusted P value<0.0001). Such pattern was also seen for Lnc-FOXF1 (Expression ratio (95% CI)= 6.41 (2.84-14.3), adjusted P value<0.0001 and Expression ratio (95% CI)= 14.41 (3.2-64.44), adjusted P value<0.0001, respectively). ITPR1 was down-regulated in total patients compared with total controls (Expression ratio (95% CI)= 0.22 (0.076-0.67), adjusted P value=0.0079). ROC curve analyses demonstrated that FOS had the best AUC value among other genes in differentiation between patients and controls (AUC=0.78).
CONCLUSIONS: The above-mentioned results imply dysregulation of oxytocin-related genes in the circulatory blood of patients with schizophrenia.

OBJECTIVE: To explore the expression changes and roles of the RNA-binding protein RCAN1.1 in acute ischemic stroke (AIS), and to preliminarily confirm the medicinal value of the RNA aptamer R1SR13 in AIS by targeting RCAN1.1.
METHODS: Two mouse AIS models of middle cerebral artery occlusion (MCAO) and right common carotid artery ligation (R-CCAL) and oxygen glucose deprivation (OGD) model of AIS in primary neurons and SH-SY5Y were performed. The expression pattern of RCAN1.1 was assessed using real-time quantitative PCR (RT-qPCR) and western blotting (WB) in vivo and in vitro. The underlying mechanism for the elevation of RCAN1.1 in the upstream was investigated. Lentiviruses were administrated and the effect of RCAN1.1 in AIS was assessed by ATP level, caspase 3/7 assay, TUNEL and WB. The protective function of R1SR13 in AIS was evaluated both in vivo and in vitro.
RESULTS: In two mouse models of AIS, RCAN1.1 mRNA and RCAN1.1 L protein were significantly upregulated in the ischemic brain tissue. The same results were detected in the OGD model of primary neurons and SH-SY5Y. The mechanistic analysis proved that hypoxia-inducible factor-1α (HIF1α) could specifically activate the RCAN1.1 gene promoter through combining with the functional hypoxia-responsive element (HRE) site (-325 to -322 bp). The increased expression of RCAN1.1 L markedly depleted ATP production and aggravated neuronal apoptosis under OGD condition. R1SR13, an antagonizing RNA aptamer of RCAN1.1, was demonstrated to reduce neuronal apoptosis caused by the elevated RCAN1.1 L in the cellular and animal models of AIS.
CONCLUSIONS: RCAN1.1 is a novel target gene of HIF1α and the functional HRE in the RCAN1.1 promoter region is -325 to -322 bp. The marked upregulation of RCAN1.1 in AIS promoted neuronal apoptosis, an effect that could be reversed by its RNA aptamer R1SR13 in vivo and in vitro. Thus, R1SR13 represents a promising strategy for neuroprotection in AIS and our study lays a theoretical foundation for it to become a clinically targeted drug.

To investigate the relationship between small noncoding microRNA-103 (miR-103) and wound healing of diabetic foot ulcers (DFU) and the underlying molecular mechanism, forty type 2 diabetes mellitus with DFU (DFU group), and 20 patients with a chronic skin ulcer of lower limbs and normal glucose tolerance (SUC group) were included. Quantitative real-time PCR method was used to determine miR-103 expression levels in the wound margin tissue of subjects, and to analyse the relationship between the expression of miR-103 and DFU wound healing. In vitro experiments were also performed to understand the effect of miR-103 on the high glucose-induced injury of normal human dermal fibroblasts (NHDFs) cells. The results showed that the miR-103 expression level in the DFU group was significantly higher than that in the SUC group [5.81 (2.25-9.36) vs 2.08 (1.15-5.72)] (P < 0.05). The expression level of miR-103 in the wound margin tissue of DFU was negatively correlated with the healing rate of foot ulcers after four weeks (P = 0.037). In vitro experiments revealed that miR-103 could inhibit the proliferation and migration of NHDF cells and promote the apoptosis of NHDF cells by targeted regulation of regulator of calcineurin 1 (RCAN1) gene expression in a high glucose environment. Down-regulation of miR-103 could alleviate high glucose-induced NHDF cell injury by promoting RCAN1 expression. Therefore, the increased expression of miR-103 is involved in the functional damage of NHDF cells induced by high-glucose conditions, which is related to poor wound healing of DFU. These research findings will provide potential targets for the diagnosis and treatment of chronic skin wounds in diabetes.

Cancer is the leading cause of mortality worldwide. Regulator of calcineurin 1 (RCAN1), as a patent endogenous inhibitor of calcineurin, plays crucial roles in the pathogenesis of cancers. Except for hypopharyngeal and laryngopharynx cancer, high expression of RCAN1 inhibits tumor progression. Molecular antitumor functions of RCAN1 are largely dependent on calcineurin. In this review, we highlight current research on RCAN1 characteristics, and the interaction between RCAN1 and calcineurin. Moreover, the dysregulation of RCAN1 in various cancers is reviewed, and the potential of targeting RCAN1 as a new therapeutic approach is discussed.