Search Results (62)

Regulation of all-trans retinoic acid (ATRA) signaling is crucial to early embryonic development. Embryonic stem (ES) cell-derived gastruloids mimic normal development in response to the Wnt/β-catenin agonist CHIR9901, and this study has examined the importance of the activities of RAR (retinoic acid receptor) α and γ to gastruloid development. Expression of retinoic acid receptor (RAR)γ within developing gastruloids was spatially restricted to primitive cells that co-expressed ES cell and early progenitor cell markers, i.e., Nanog, Sox2, and Oct4. In contrast, RARα expression was ubiquitous. mRNAs for the key enzymes involved in ATRA synthesis (Aldh1a2) and degradation (Cyp26a1) were not seen in cells that expressed RARγ. Treatment of ES cell-derived gastruloids with physiologically relevant (10 nm) levels of ATRA or with a highly selective RARγ agonist blocked normal developmental processes, preventing symmetry-breaking and axial elongation. This was not seen following treatments with an RARα agonist, where there was a tendency for enhanced axial elongation. Brachyury (TBXT) immuno-positive cells localized in the posterior end of elongated gastruloids in control- and RARα agonist-treated cultures, with Sox2 immuno-positive cells seen more widely, whilst both TBXT and Sox2 immuno-positive cells were randomly distributed throughout ATRA- and RARγ agonist-treated gastruloids. Concurrent treatment of gastruloids with 10 nm ATRA and 100 nm of an RARγ antagonist partially abrogated the ATRA-mediated block to axial elongation. Conversely, 10 nm RARγ antagonist treatments were associated with the formation of multi-axis gastruloid elongations, with comparatively little effect seen after treatments with an RARα antagonist. These findings reveal that RARγ plays a crucial role in the development of embryonic tissues. Full article

Background/Objectives: Acute myeloid leukemia (AML) comprises a heterogeneous group of diseases, with some subtypes displaying promyelocytic features and altered differentiation programs. Aberrant cytokine receptor signaling has been implicated in leukemogenesis, and IL-5Rα has recently emerged as a potential marker in selected AML subsets, including promyelocytic variants. Benralizumab is a monoclonal antibody directed against the alpha chain of the interleukin-5 receptor (CD125), which blocks IL-5Rα–mediated signaling. This proof-of-concept study aimed to explore the effects of the anti-IL-5Rα monoclonal antibody Benralizumab in an in vitro AML cell model with promyelocytic characteristics. Methods: Public transcriptomic datasets were analyzed to evaluate IL-5Rα expression in AML subtypes. HL-60 cells, an AML cell line expressing IL-5Rα, were treated with Benralizumab and analyzed for cell cycle distribution and modulation of key signaling and apoptotic pathways by flow cytometry and Western blotting. Results: IL-5Rα was highly expressed in AML, particularly in M2 and M3 subtypes. Benralizumab treatment reduced STAT3 expression, activated ERK and NF-κB signaling, induced p21 and p27 expression, altered cell cycle distribution, and induced caspase-8 cleavage, suggesting activation of extrinsic apoptotic signaling. Conclusions: These findings provide preliminary proof-of-concept evidence that IL-5Rα targeting by Benralizumab may directly affect cell survival and cell cycle regulation in AML cells with promyelocytic characteristics. When interpreted together with the in silico analyses performed on AML patient datasets, these results support the rationale for future validation in APL-oriented models carrying the PML::RARα fusion, the disease-defining oncogenic driver generated by the t(15;17) translocation that blocks myeloid differentiation. However, the in silico and in vitro datasets were not formally integrated at the patient level, and these functional results should be considered exploratory. Full article

(1) Background: All-trans retinoic acid (ATRA) has transformed the treatment of acute promyelocytic leukemia (APL) by inducing terminal myeloid differentiation. However, its efficacy in non-APL acute myeloid leukemia (AML) is limited. Exploring combination strategies that enhance ATRA-induced differentiation may broaden its therapeutic potential. (2) Methods: A literature search of PubMed using the keywords “ATRA,” “myeloid,” and “differentiation inducer or enhancer” identified more than 500 published papers as of November 2025. Pre-clinical and clinical studies were reviewed, with a focus on mechanisms, combination partners, and translational relevance. (3) Results: Clinical evidence confirms that ATRA combined with arsenic trioxide or epigenetic modulators achieves high remission rates in APL and selected AML subtypes. Pre-clinical studies show synergistic differentiation effects when ATRA is combined with CDK and kinase inhibitors, nucleotide synthesis inhibitors, DNA-damaging agents, Bcl-2/MDM2 inhibitors, proteasome inhibitors, cytokines, glycosylation modifiers, natural products, and antibiotic-derived compounds. Mechanistically, these combinations modulate key signaling pathways (MAPK, Akt, JAK/STAT), stabilize RARα, remodel chromatin, and perturb nucleotide metabolism. Although translation to non-APL AML remains limited, these findings provide a rational basis for future clinical trials. (4) ATRA-based combination therapies represent a promising strategy to extend differentiation therapy beyond APL. This review, authored solely by the investigator, highlights molecular targets and potential enhancers warranting further clinical evaluation in AML. Full article

This study investigated the interactive effects of dietary vitamin A (VA) and all-trans retinoic acid (ATRA) on growth performance and intestinal health in broilers. A total of 432 one-day-old male Arbor Acres chicks were assigned to a 2 × 3 factorial design with two VA levels (2000 and 6000 IU/kg) and three ATRA levels (0, 0.25, and 0.50 mg/kg). The maize–soybean meal basal diet contained 180 IU/kg VA without extra VA supplementation. Results showed that compared with 0 mg/kg ATRA, 0.50 mg/kg ATRA enhanced average daily gain (ADG) during days 1–21 (p < 0.05). Compared with 2000 IU/kg VA, 6000 IU/kg VA improved body weight on day 35 as well as ADG and feed intake during days 22–35 and reduced feed conversion ratio over the entire trial (p < 0.05). There were VA × ATRA interactions for the ratio of villus height (VH) to crypt depth (CD) in duodenum as well as VH and CD in ileum on day 21 (p < 0.05). The 0.25 mg/kg ATRA decreased duodenal VH/CD and ileal VH in broilers fed 2000 and 6000 IU/kg VA, respectively (p < 0.05). The 0.50 mg/kg ATRA increased ileal VH in broilers fed both 2000 and 6000 IU/kg VA (p < 0.05). When birds were fed 6000 IU/kg VA, 0.50 mg/kg ATRA increased ileal CD compared with 0.25 mg/kg CD (p < 0.05). On day 35, compared with 0 mg/kg ATRA, 0.25 mg/kg ATRA increased ileal VH while 0.50 mg/kg ATRA decreased ileal CD, and both of them increased ileal VH/CD (p < 0.05). The VA × ATRA interactions for mRNA expression of jejunal Mucin5ac on day 21 and jejunal Occludin, Claudin-1, Mucin 2, leucine-rich-repeat-containing G-protein-coupled receptor 5⁺ (Lgr5⁺), zinc and ring finger 3 (Znrf3), and secreted phosphoprotein 1 (SPP1) on day 35 were detected (p < 0.05). Dietary 0.50 mg/kg ATRA up-regulated jejunal Mucin5ac expression in broilers fed 6000 IU/kg VA on day 21 as well as Claudin-1, Znrf3, and SPP1 expression broilers fed 2000 IU/kg VA on day 35 (p < 0.05). The 0.25 mg/kg ATRA down-regulated Occludin expression in broilers fed 6000 IU/kg VA on day 35 (p < 0.05). The 0.25 mg/kg ATRA decreased and increased Lgr5⁺ expression on day 35 in broilers fed 2000 and 6000 IU/kg VA, respectively (p < 0.05). Both 0.25 and 0.50 mg/kg ATRA down-regulated Mucin-2 expression in broilers fed 2000 IU/kg VA on day 35 (p < 0.05). The VA × ATRA interactions were observed for jejunal retinol dehydrogenase 10 (RDH10), cytochrome P450, family 26, subfamily A, polypeptide 1 (CYP26A1), retinoic acid receptor (RAR) α, and RARβ expression on days 21 and 35 (p < 0.05). Both 0.25 and 0.50 mg/kg up-regulated RDH10, CYP26A1, and RARβ expression in broilers fed 6000 IU/kg VA (p < 0.05). The RARα expression was up-regulated by 0.50 and 0.25 mg/kg ATRA on days 21 and 35, respectively (p < 0.05). Plasma metabolomics identified 269 VA- and 185 ATRA-associated differential metabolites, primarily enriched in lipid metabolism, vitamin digestion and absorption, and bacterial infection pathways. In conclusion, dietary 0.50 mg/kg ATRA and 6000 IU/kg VA enhanced growth performance, intestinal integrity, and VA metabolism, partly through activation of retinoic acid receptors and modulation of plasma lipid metabolism. Full article

Background: Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia driven by the PML/RARα fusion protein. Standard treatment with all-trans retinoic acid (ATRA) combined with chemotherapy is effective, but resistance and adverse effects remain significant challenges. Melittin, the primary peptide component of bee venom, has demonstrated potent anticancer activity across multiple leukemia subtypes through mitochondrial-dependent mechanisms. Building upon this established evidence, we investigated melittin’s therapeutic potential in APL to address the specific clinical challenge of ATRA resistance. Methods: The cytotoxic and pro-apoptotic effects of melittin were studied on the human APL cell line HL-60. Cell viability was assessed using MTT and trypan blue assays. Mitochondrial membrane potential (MMP) was measured with JC-1 staining. Apoptosis was quantified using Annexin V/propidium iodide flow cytometry, caspase-3/7 activity assays, and real-time PCR analysis of apoptosis-related genes (BCL-2, BAX, APAF-1, CASP-3, CASP-8, CASP-9). Results: Melittin reduced HL-60 cell viability in a dose- and time-dependent manner, with significant decreases after 24 and 48 h. MMP analysis revealed mitochondrial depolarization, and Annexin V staining confirmed the induction of apoptosis. Caspase-3/7 activity increased markedly, supporting activation of the intrinsic apoptotic pathway. Gene expression profiling revealed downregulation of the anti-apoptotic BCL-2 and upregulation of the pro-apoptotic BAX, APAF1, and CASP3. At the same time, CASP8 and CASP9 showed no significant changes, suggesting a predominant involvement of the intrinsic pathway. Conclusions: These findings confirm and extend established evidence by demonstrating that melittin’s mitochondrial apoptotic mechanism is consistently active in promyelocytic HL-60 model (PML/RARα-negative). This retinoid-independent mechanism suggests potential therapeutic utility for ATRA-resistant cases or as a complementary strategy in APL treatment. However, selectivity validation in non-cancerous hematopoietic cells represents an important future research priority. Full article

Background. Medulloblastoma (MB) prognosis and response to therapy depend largely on genetic changes in tumor cells. Many genes and chromosomal abnormalities have been identified as prognostic factors, including amplification of MYC oncogenes, gains in 1q and 17q, deletions in 10q and 21p, or isochromosomes 17 (i(17)(q10)). The frequency of these abnormalities varies greatly between ethnic populations, but the frequency of specific abnormalities, such as MYCC and MYCN amplification, 17q gain, and deletions, in the Russian population is unknown. Objective: The aim is to study the frequency of MYCC and MYCN amplifications, 17q gain, and 17p deletion and determine their prognostic value in Russian patients with MB. Methods. This study was performed on MB cells obtained from 18 patients (12 boys and 6 girls, aged between 3 months and 17 years, with a median age of 6.5 years). Determination of cytogenetic aberrations was carried out using FISH assays with MYCC-SO, MYCN-SO, and MYCN-SG/cen2 probes, as well as cen7/p53 dual color probes and PML/RARα dual color probes (Abbott Molecular, USA). One-way ANOVA and Fisher’s F-test were used to compare the two groups. The differences were considered significant when p < 0.05. Results. In 77.7% of patients (14/18), the classical type of MB was present; in 16.7% (3/18), desmoplastic type; and in 5.6% (1/18), nodular desmoplasic types of neoplasms. Amplification of MYC genes was detected in 22.2% of Russian patients (n = 4 out of 18). Patients with MYC amplification had the worst overall survival (OS: 0% vs. 68%, p = 0.0004). Changes on the 17th chromosome were found in 58.3% of patients. Deletion of 17p occurred in 23.1%, and gain of 17q occurred in 46.2%. There were no significant differences in OS, clinical signs, or the presence of additional 17q material or 17p deletion among patients with MB. Conclusions: Amplification of the MYC gene is a predictor of poor overall survival to therapy and a high risk of metastatic relapse. This allows us to more accurately stratify patients into risk groups in order to determine the intensity and duration of therapy. Full article

An obstacle for many microfluidic developments is the fabrication of its structures, which is often complex, time-consuming, and expensive. Additive manufacturing can help to reduce these barriers. This study investigated whether the results of a microfluidic assay for the detection of the promyelocytic leukemia (PML)-retinoic acid receptor α (RARα) fusion protein (PML::RARA), and thus for the differential diagnosis of acute promyelocytic leukemia (APL), could be transferred from borosilicate glass microfluidic structures to additively manufactured fluidics. Digital light processing (DLP) and stereolithography (SLA) printers as well as different photopolymerizable methacrylate-based resins were tested for fabrication of the fluidics. To assess suitability, both print resolution and various physical properties, serializability, biocompatibility, and functionalization with biological molecules were analyzed. The results show that additively manufactured microfluidics are suitable for application in leukemia diagnostics. This was demonstrated by transferring the microfluidic sandwich enzyme-linked immunosorbent assay (ELISA) for PML::RARA onto the surface of magnetic microparticles from a glass structure to three-dimensional (3D)-printed parts. A comparison with conventional glass microstructures suggests lower sensitivity but highlights the potential of additive manufacturing for prototyping microfluidics. This may contribute to the wider use of microfluidics in biotechnological or medical applications. Full article

All-trans retinoic acid (ATRA), the major active metabolite of all-trans retinol (vitamin A), is a key hormonal signaling molecule. In the adult organism, ATRA has a widespread influence on processes that are crucial to the growth and differentiation of cells and, in turn, the acquisition of mature cell functions. Therefore, there is considerable potential in the use of retinoids to treat diseases. ATRA binds to the retinoic acid receptors (RAR) which, as activated by ATRA, selectively regulate gene expression. There are three main RAR isoforms, RARα, RARβ, and RARγ. They each have a distinct role, for example, RARα and RARγ regulate myeloid progenitor cell differentiation and hematopoietic stem cell maintenance, respectively. Hence, targeting an isoform is crucial to developing retinoid-based therapeutics. In principle, this is exemplified when ATRA is used to treat acute promyelocytic leukemia (PML) and target RARα within PML-RARα oncogenic fusion protein. ATRA with arsenic trioxide has provided a cure for the once highly fatal leukemia. Recent in vitro and in vivo studies of RARγ have revealed the potential use of agonists and antagonists to treat diseases as diverse as cancer, heterotopic ossification, psoriasis, and acne. During the final drug development there may be a need to design newer compounds with added modifications to improve solubility, pharmacokinetics, or potency. At the same time, it is important to retain isotype specificity and activity. Examination of the molecular interactions between RARγ agonists and the ligand binding domain of RARγ has revealed aspects to ligand binding that are crucial to RARγ selectivity and compound activity and key to designing newer compounds. Full article

Retinoic acid-induced 1 (RAI1) is a dosage-sensitive gene that causes autistic phenotypes when deleted or duplicated. Observations from clinical cases and animal models also suggest that changes of RAI1 expression levels contribute to autism. Previously, we used a bioinformatic approach to identify several single nucleotide polymorphisms (SNPs) located within the 5′-region of RAI1 that correlate with RAI1 mRNA expression in the human brain. In particular, the SNP rs4925102 was identified as a candidate cis-acting regulatory variant, the genotype of which may affect the binding of transcription factors that influence RAI1 mRNA expression. In this study, we provide experimental evidence based on reporter gene, chromatin immunoprecipitation (ChIP), and chromatin conformation capture (3C) assays that rs4925102 regulates RAI1 mRNA expression in an allele-specific manner in human cell lines, including the neuroblastoma-derived cell line SH-SY5Y. We also describe a statistically significant association between rs4925102 genotype and autism spectrum disorder (ASD) diagnosis in a case-control study and near-statistically significant association in an Autism Genome Project (AGP) transmission disequilibrium (TDT) study using Caucasian subjects. Full article

N-retinylidene-N-retinylethanolamine (A2E) has been associated with age-related macular degeneration (AMD) physiopathology by inducing cell death, angiogenesis and inflammation in retinal pigmented epithelial (RPE) cells. It was previously thought that the A2E effects were solely mediated via the retinoic acid receptor (RAR)-α activation. However, this conclusion was based on experiments using the RAR “specific” antagonist RO-41-5253, which was found to also be a ligand and partial agonist of the peroxisome proliferator-activated receptor (PPAR)-γ. Moreover, we previously reported that inhibiting PPAR and retinoid X receptor (RXR) transactivation with norbixin also modulated inflammation and angiogenesis in RPE cells challenged in the presence of A2E. Here, using several RAR inhibitors, we deciphered the respective roles of RAR, PPAR and RXR transactivations in an in vitro model of AMD. We showed that BMS 195614 (a selective RAR-α antagonist) displayed photoprotective properties against toxic blue light exposure in the presence of A2E. BMS 195614 also significantly reduced the AP-1 transactivation and mRNA expression of the inflammatory interleukin (IL)-6 and vascular endothelial growth factor (VEGF) induced by A2E in RPE cells in vitro, suggesting a major role of RAR in these processes. Surprisingly, however, we showed that (1) Norbixin increased the RAR transactivation and (2) AGN 193109 (a high affinity pan-RAR antagonist) and BMS 493 (a pan-RAR inverse agonist), which are photoprotective against toxic blue light exposure in the presence of A2E, also inhibited PPARs transactivation and RXR transactivation, respectively. Therefore, in our in vitro model of AMD, several commercialized RAR inhibitors appear to be non-specific, and we propose that the phototoxicity and expression of IL-6 and VEGF induced by A2E in RPE cells operates through the activation of PPAR or RXR rather than by RAR transactivation. Full article

Polychlorinated biphenyls (PCBs) are organic chemicals consisting of a biphenyl structure substituted with one to ten chlorine atoms, with 209 congeners depending on the number and position of the chlorine atoms. PCBs are widely known to be endocrine-disrupting chemicals (EDCs) and have been found to be involved in several diseases/disorders. This study takes various molecular descriptors of these PCBs (e.g., molecular weight) and toxicity endpoints as molecular activities, investigating the possibility of correlations via the quantitative structure–toxicity relationship (QSTR). This study then focuses on molecular docking and dynamics to investigate the docking behavior of the strongest-binding PCBs to nuclear receptors and compares these to the docking behavior of their natural ligands. Nuclear receptors are a family of transcription factors activated by steroid hormones, and they have been investigated to consider the impact of PCBs on humans in this context. It has been observed that the docking affinity of PCBs is comparable to that of the natural ligands, but they are inferior in terms of stability and interacting forces, as shown by the RMSD and total energy values. However, it is noted that most nuclear receptors respond to PCBs similarly to how they respond to their natural ligands—as shown in the RMSF plots—the most similar of which are seen in the ER, THR-β, and RAR-α. However, this study is performed purely in silico and will need experimental verification for validation. Full article

Postoperative cognitive dysfunction (POCD) is a clinical syndrome characterizing by cognitive impairments in the elderly after surgery. There is limited effective treatment available or clear pathological mechanisms known for this syndrome. In this study, a Connectivity Map (CMap) bioinformatics model of POCD was established by using differently expressed landmark genes in the serum samples of POCD and non-POCD patients from the only human transcriptome study. The predictability and reliability of this model were further supported by the positive CMap scores of known POCD inducers and the negative CMap scores of anti-POCD drug candidates. Most retinoic acid receptor (RAR) agonists were negatively associated with POCD in this CMap model, suggesting that RAR might be a novel target for POCD. Most importantly, acitretin, a clinically used RAR agonist, significantly inhibited surgery-induced cognitive impairments and prevented the reduction in RARα and RARα-target genes in the hippocampal regions of aged mice. The study denotes a reliable CMap bioinformatics model of POCD for future use and establishes that RAR is a novel therapeutic target for treating this clinical syndrome. Full article

Vitamin A (VitA) is an important fat-soluble vitamin which plays an important role in cell growth and individual development. However, the effect of VitA on the repair process of muscle injury and its molecular mechanism are still unclear. In this study, VitA and RA were first added to the culture medium of differentiated cells. We then detected cell differentiation marker proteins and myotube fusion. Moreover, the effects of VitA on RARα expression and nuclear translocation were further examined. The results showed that VitA significantly promoted the differentiation of C2C12, and the expression of RARα was significantly increased. Furthermore, VitA was injected into skeletal muscle injury in mice. HE staining and Western Blot results showed that VitA could significantly accelerate the repair of skeletal muscle injury and VitA increase the expression of RARα in mice. This study provides a theoretical basis for elucidating the regulation mechanism of VitA-mediated muscle development and the development of therapeutic drugs for muscle diseases in animals. Full article

In this study we analyzed the expression of Yin and Yang 1 protein (YY1), a member of the noncanonical PcG complexes, in AML patient samples and AML cell lines and the effect of YY1 downregulation on the AML differentiation block. Our results show that YY1 is significantly overexpressed in AML patient samples and AML cell lines and that YY1 knockdown relieves the differentiation block. YY1 downregulation in two AML cell lines (HL-60 and OCI-AML3) and one AML patient sample restored the expression of members of the CEBP protein family, increased the expression of extrinsic growth factors/receptors and surface antigenic markers, induced morphological cell characteristics typical of myeloid differentiation, and sensitized cells to retinoic acid treatment and to apoptosis. Overall, our data show that YY1 is not a secondary regulator of myeloid differentiation but that, if overexpressed, it can play a predominant role in myeloid differentiation block. Full article

Cancer stem cells are the root cause of cancer, which, in essence, is a developmental disorder. All-trans retinoic acid (ATRA) signaling via ligand-activation of the retinoic acid receptors (RARs) plays a crucial role in tissue patterning and development during mammalian embryogenesis. In adults, active RARγ maintains the pool of hematopoietic stem cells, whereas active RARα drives myeloid cell differentiation. Various findings have revealed that ATRA signaling is deregulated in many cancers. The enzymes for ATRA synthesis are downregulated in colorectal, gastric, lung, and oropharyngeal cancers. ATRA levels within breast, ovarian, pancreatic, prostate, and renal cancer cells were lower than within their normal counterpart cells. The importance is that 0.24 nM ATRA activates RARγ (for stem cell stemness), whereas 100 times more is required to activate RARα (for differentiation). Moreover, RARγ is an oncogene regarding overexpression within colorectal, cholangiocarcinoma, hepatocellular, ovarian, pancreatic, and renal cancer cells. The microRNA (miR) 30a-5p downregulates expression of RARγ, and miR-30a/miR-30a-5p is a tumor suppressor for breast, colorectal, gastric, hepatocellular, lung, oropharyngeal, ovarian, pancreatic, prostate, and renal cancer. These complementary findings support the view that perturbations to ATRA signaling play a role in driving the abnormal behavior of cancer stem cells. Targeting ATRA synthesis and RARγ has provided promising approaches to eliminating cancer stem cells because such agents have been shown to drive cell death. Full article