C286, an orally available retinoic acid receptor ß agonist drug, regulates multiple pathways to achieve spinal cord injury repair.

Retinoic acid receptor ß2 (RARß2) is an emerging therapeutic target for spinal cord injuries (SCIs) with a unique multimodal regenerative effect. We have developed a first-in-class RARß agonist drug, C286, that modulates neuron-glial pathways to induce functional recovery in a rodent model of sensory root avulsion. Here, using genome-wide and pathway enrichment analysis of avulsed rats' spinal cords, we show that C286 also influences the extracellular milieu (ECM). Protein expression studies showed that C286 upregulates tenascin-C, integrin-α9, and osteopontin in the injured cord. Similarly, C286 remodulates these ECM molecules, hampers inflammation and prevents tissue loss in a rodent model of spinal cord contusion C286. We further demonstrate C286's efficacy in human iPSC-derived neurons, with treatment resulting in a significant increase in neurite outgrowth. Additionally, we identify a putative efficacy biomarker, S100B, which plasma levels correlated with axonal regeneration in nerve-injured rats. We also found that other clinically available retinoids, that are not RARß specific agonists, did not lead to functional recovery in avulsed rats, demonstrating the requirement for RARß specific pathways in regeneration. In a Phase 1 trial, the single ascending dose (SAD) cohorts showed increases in expression of RARß2 in white blood cells correlative to increased doses and at the highest dose administered, the pharmacokinetics were similar to the rat proof of concept (POC) studies. Collectively, our data suggests that C286 signalling in neurite/axonal outgrowth is conserved between species and across nerve injuries. This warrants further clinical testing of C286 to ascertain POC in a broad spectrum of neurodegenerative conditions.

The order of green and red LEDs irradiation affects the neural differentiation of human umbilical cord matrix-derived mesenchymal cells.

Different wavelengths emitted from light-emitting diodes (LEDs) are known as an influential factor in proliferation and differentiation of various cell types. Since human umbilical cord matrix-derived mesenchymal cells (hUCMs) are ideal tools for human regenerative medicine clinical trials and stem cell researches, in the present study we investigated the neurogenesis effects of single and intermittent green and red LED irradiation on hUCM cells. Exposure of hUCMs to single and intermittent green (530 nm, 1.59 J/cm2) and red (630 nm, 0.318 J/cm2) lights significantly increased the expression of specific genes including nestin, ß-tubulin III and Olig2. Additionally, immunocytochemical analysis confirmed the expression of specific neural-related proteins including nestin, ß-tubulin III, Olig2 and GFAP. Also, alternating exposure of hUCM cells to green and red lights increased the expression of some neural markers more than either light alone. Further research are required to develop the application of LED irradiation as a useful tool for therapeutic purposes including neural repair and regeneration.

Therapy-related myeloid neoplasms following curative treatment of acute promyelocytic leukemia: incidence, correlation with therapeutic regimen, and future directions.

All-trans retinoic acid (ATRA) and arsenic trioxide (ATO) have revolutionized the treatment of acute promyelocytic leukemia (APL), offering a cure rate of > 80%. Along with improved survival, the long-term consequences of anti-APL therapy are becoming increasingly apparent, including potential therapy-related myeloid neoplasms (t-MNs). T-MNs are well known to arise after cytotoxic chemotherapy, but the leukemogenic potential of regimens utilizing only ATRA/ATO is not well established. The objective of this study is to examine the incidence, long-term risk, and clinicopathologic features of t-MNs arising after anti-APL therapy and how they correlates with the therapeutic regimen employed. We retrospectively collected treated APL patients between 01/2001 and 02/2021, categorized them into ATRA/ATO + chemo and ATRA/ATO groups based on the regimen used, and evaluated for the development of t-MN. A total of 110 APL patients were identified, including 67 (61%) treated with ATRA/ATO + chemo and 43 (39%) treated with ATRA/ATO only. Overall, 4/110 (3.6%) patients developed t-MNs, with all four emerging in the ATRA/ATO + chemo group. Ultimately, the incidence of t-MN in ATRA/ATO + chemo group was significantly higher compared with ATRA/ATO only group(5.97% vs. 0.0%, respectively; p = 0.0289). Our data spanning over two decades suggests that conventional chemotherapy for APL is associated with a small but significant risk of t-MN, whereas ATR/ATO does not carry this risk. This takes on new significance, considering several recent and ongoing trials have shown that a chemotherapy-free approach might become feasible for all risk APL types in the near future. Consequently, the omission of leukemogenic and arguably unnecessary chemotherapy from APL regimens may reduce the incidence of t-MNs in long-term survivors without sacrificing their cure rates.

Characterization of the C17.2 cell line as testing system for endocrine disruption-induced developmental neurotoxicity.

Hormone signaling plays an essential role during fetal life and is vital for brain development. Endocrine-disrupting chemicals can interfere with the hormonal milieu during this critical time-period, disrupting key neurodevelopmental processes. Hence, there is a need for the development of assays that evaluate developmental neurotoxicity (DNT) induced by an endocrine mode of action. Herein, we evaluated the applicability of the neural progenitor C17. 2 cell-line, as an in vitro test system to aid in the detection of endocrine disruption (ED) induced DNT. For this, C17.2 cells were exposed during 10 days of differentiation to agonists and antagonists of the thyroid hormone (Thr), glucocorticoid (Gr), retinoic acid (Rar), retinoic x (Rxr), oxysterols (Lxr), estrogen (Er), androgen (Ar), and peroxisome proliferator activated delta (Pparß/δ) receptors, as well as to the agonist of the vitamin D (Vdr) receptor. Upon exposure and differentiation, neuronal morphology (neurite outgrowth and branching), and the percentage of neurons in culture were assessed by immunofluorescence. For this, the cells were incubated with Hoechst (nuclear staining) and stained for ßIII-tubulin (neuronal marker). The C17.2 cells were responsive to the Rar, Rxr and Pparß/δ agonists which decreased neurite outgrowth and branching. Additionally, exposure to the Gr agonist increased the number of cells differentiating into neurons, while exposure to the Rxr agonist had the opposite effect. With this approach, we have identified that the C17.2 cells are responsive to Gr, Rar, Rxr, and Pparß/δ agonists, hence contributing to the development of test systems for hazard assessment of ED-induced DNT.

Endocrine disrupting chemicals (EDCs) interfere with hormonal signaling. As hormones play a vital role for an organism's development, EDC exposure is of high concern. In European regulations, the use of a chemical can be restricted if its toxicity is mediated by hormonal interference. A number of EDCs affect brain development. However, in animal tests, it is impossible to prove that a chemical induces developmental neurotoxicity (DNT) via endocrine disruption (ED). Furthermore, the regulatory DNT tests require large amounts of animals. Thus, there is an urgent need for in vitro test systems to identify ED-induced DNT. Herein we present the development of such a method based on the murine neural progenitor cell-line C17.2 with which neuronal differentiation processes can be mimicked. We show that differentiation of C17.2 cells are sensitive to retinoid, glucocorticoid, and peroxisome proliferator activated receptor signaling disruption, thus providing an alternative method for identifying ED-induced DNT.

Dual and opposing role of retinoic acid receptor signaling in mesenchymal stem cells for tendon ossification in mice.

Heterotopic ossification is abnormal bone formation in soft tissues that occurs primarily after injury and major surgery. This condition often causes local pain and limits joint motion in the affected limb. Currently, there is no effective treatment or prophylaxis for this condition other than surgical removal of the lesion. Recent studies suggest that retinoic acid receptor (RAR) agonists are effective in suppressing heterotopic ossification in patients with Fibrodysplasia Ossificans Progressiva, a congenital disorder characterized by progressive ossification of soft tissue, by suppressing the aberrant differentiation of mesenchymal stem cells in muscle. In this study, we aimed to elucidate the potential use of RAR agonists in suppressing injury-induced ectopic tendon ossification using a mouse Achilles tenotomy model. Contrary to our initial hypothesis, administration of RAR agonists throughout the experimental period (5 weeks) accelerated ectopic tendon ossification in our model. Of note, in vitro differentiation experiments using tendon-derived mesenchymal stem cells revealed that RAR agonists play opposing roles in osteogenic and chondrogenic differentiation, promoting the former and suppressing the latter. Indeed, we found that RAR agonists suppressed tendon ossification when administered before cartilage nodule formation, but promoted it when administered after. These results suggest that RAR agonists have a dual and opposing effect on tendon ectopic ossification, depending on the duration and timing of their administration. Our data may provide a basis for further investigation of the potential use of RAR agonists in the treatment of injury-induced heterotopic ossification.

Exosomes-mediated retinoic acid disruption: A link between gut microbiota depletion and impaired spermatogenesis.

Gut microbiota symbiosis faces enormous challenge with increasing exposure to drugs such as environmental poisons and antibiotics. The gut microbiota is an important component of the host microbiota and has been proven to be involved in regulating spermatogenesis, but the molecular mechanism is still unclear. A male mouse model with gut microbiota depletion/dysbiosis was constructed by adding combined antibiotics to free drinking water, and reproductive parameters such as epididymal sperm count, testicular weight and paraffin sections were measured. Testicular transcriptomic and serum metabolomic analyses were performed to reveal the molecular mechanism of reproductive dysfunction induced by gut microbiota dysbiosis in male mice.This study confirms that antibiotic induced depletion of gut microbiota reduces sperm count in the epididymis and reduces germ cells in the seminiferous tubules in male mice. Further study showed that exosomes isolated from microbiota-depleted mice led to abnormally high levels of retinoic acid and decrease in the number of germ cells in the seminiferous tubules and sperm in the epididymis. Finally, abnormally high levels of retinoic acid was confirmed to disrupted meiotic processes, resulting in spermatogenesis disorders. This study proposed the concept of the gut microbiota-exosome-retinoic acid-testicular axis and demonstrated that depletion of the gut microbiota caused changes in the function of exosomes, which led to abnormal retinoic acid metabolism in the testis, thereby impairing meiosis and spermatogenesis processes.

Triazole fungicides disrupt embryonic stem cell differentiation: Potential modulatory role of the retinoic acid signaling pathway.

The developmental toxicity and human health risks of triazole fungicides (TFs) have attracted worldwide attention due to the ability to enter the human body in a variety of ways. Nevertheless, the specific mechanism by which TFs exert remains incompletely understood. Given that retinoic acid (RA) signaling pathway are closely related to development, this study aimed to screen and identify developmentally disabled chemicals in commonly used TFs and to reveal the potential effects of TFs on developmental retardation through the RA signaling pathway in mouse embryonic stem cells (mESCs). Specifically, six typical TFs (myclobutanil, tebuconazole, hexaconazole, propiconazole, difenoconazole, and flusilazole) were exposed through the construction of an embryoid bodies (EBs)-based in vitro global differentiation models. Our results clarified that various TFs disturbed lineage commitment during early embryonic development. Crucially, the activation of RA signaling pathway, which alters the expression of key genes and interferes the transport and metabolism of retinol, may be responsible for this effect. Furthermore, molecular docking, molecular dynamics simulations, and experiments using a retinoic acid receptor α inhibitor provide evidence supporting the potential modulatory role of the retinoic acid signaling pathway in developmental injury. The current study offers new insights into the TFs involved in the RA signaling pathway that interfere with the differentiation process of mESCs, which is crucial for understanding the impact of TFs on pregnancy and early development.

Highly Curative Treatment of High-Risk Acute Promyelocytic Leukemia: Induction and Consolidation with ATRA+ATO+anthracyclines and Maintenance with ATRA+RIF.

Background: The aim of the study was to evaluate the efficacy and safety of induction and consolidation with all-trans retinoic acid (ATRA) +arsenic trioxide (ATO) +anthracyclines and maintenance with ATRA +Realgar-Indigo naturalis formula (RIF) for high-risk APL. Methods: Twenty-one patients with high-risk APL treated with ATRA+ATO+ anthracyclines for induction and consolidation and ATRA+RIF for maintenance from 2012 to 2021 were analyzed. Endpoints include morphological complete remission (CR) and complete molecular remission (CMR), early death (ED) and relapse, survival and adverse events (AEs). Results: After induction treatment, all 21 patients (100%) achieved morphological CR and 14 people (66.7%) achieved CMR. Five of the 21 patients did not undergo immunological minimal residual disease (MRD) examination after induction; however, 14 of the remaining 16 patients were MRD negative (87.5%). The median time to achieve CR and CMR was 26 days (range: 16-44) and 40 days (range: 22-75), respectively. The cumulative probability of achieving CR and CMR in 45 days was 100% and 76.2% (95% CI: 56.9-91.3%), respectively. All patients achieved CMR and MRD negativity after the three courses of consolidation treatment. The median follow-up was 66 months (25-142), with no central nervous system relapse and bone marrow morphological or molecular relapse until now, and all patients survived with 100% overall survival and 100% event-free survival. Grade 4 adverse events (AEs) were observed in 3 patients (14.3%) during the induction period including arrhythmia (n = 1), pulmonary infection (n = 1) and respiratory failure (n = 1); and the most frequent grade 3 AEs were pulmonary infection, accounting for 62.0% and 28.6%, respectively, during induction and consolidation treatment, followed by neutropenia, accounting for 42.9% and 38.1%, respectively. Conclusion: For newly diagnosed high-risk APL patients, induction and consolidation with ATRA+ATO+anthracyclines and maintenance with ATRA+RIF is a highly curative treatment approach.

Human esophageal cancer stem-like cells escape the cytotoxicity of natural killer cells via down-regulation of ULBP-1.

BACKGROUND: Cancer stem-like cells (CSCs) play an important role in initiation and progression of aggressive cancers, including esophageal cancer. Natural killer (NK) cells are key effector lymphocytes of innate immunity that directly attack a wide variety of cancer cells. NK cell-based therapy may provide a new treatment option for targeting CSCs. In this study, we aimed to investigate the sensitivity of human esophageal CSCs to NK cell-mediated cytotoxicity. METHODS: CSCs were enriched from human esophageal squamous cell carcinoma cell lines via sphere formation culture. Human NK cells were selectively expanded from the peripheral blood of healthy donors. qRT-PCR, flow cytometry and ELISA assays were performed to examine RNA expression and protein levels, respectively. CFSE-labeled target cells were co-cultured with human activated NK cells to detect the cytotoxicity of NK cells by flow cytometry. RESULTS: We observed that esophageal CSCs were more resistant to NK cell-mediated cytotoxicity compared with adherent counterparts. Consistently, esophageal CSCs showed down-regulated expression of ULBP-1, a ligand for NK cells stimulatory receptor NKG2D. Knockdown of ULBP-1 resulted in significant inhibition of NK cell cytotoxicity against esophageal CSCs, whereas ULBP-1 overexpression led to the opposite effect. Finally, the pro-differentiation agent all-trans retinoic acid was found to enhance the sensitivity of esophageal CSCs to NK cell cytotoxicity. CONCLUSIONS: This study reveals that esophageal CSCs are more resistant to NK cells through down-regulation of ULBP-1 and provides a promising approach to promote the activity of NK cells targeting esophageal CSCs.

Key target genes related to anti-breast cancer activity of ATRA: A network pharmacology, molecular docking and experimental investigation.

All-trans retinoic acid (ATRA) has promising activity against breast cancer. However, the exact mechanisms of ATRA's anticancer effects remain complex and not fully understood. In this study, a network pharmacology and molecular docking approach was applied to identify key target genes related to ATRA's anti-breast cancer activity. Gene/disease enrichment analysis for predicted ATRA targets was performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID), the Comparative Toxicogenomics Database (CTD), and the Gene Set Cancer Analysis (GSCA) database. Protein-Protein Interaction Network (PPIN) generation and analysis was conducted via Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and cytoscape, respectively. Cancer-associated genes were evaluated using MyGeneVenn from the CTD. Differential expression analysis was conducted using the Tumor, Normal, and Metastatic (TNM) Plot tool and the Human Protein Atlas (HPA). The Glide docking program was used to predict ligand-protein binding. Treatment response predication and clinical profile assessment were performed using Receiver Operating Characteristic (ROC) Plotter and OncoDB databases, respectively. Cytotoxicity and gene expression were measured using MTT/fluorescent assays and Real-Time PCR, respectively. Molecular functions of ATRA targets (n = 209) included eicosanoid receptor activity and transcription factor activity. Some enriched pathways included inclusion body myositis and nuclear receptors pathways. Network analysis revealed 35 hub genes contributing to 3 modules, with 16 of them were associated with breast cancer. These genes were involved in apoptosis, cell cycle, androgen receptor pathway, and ESR-mediated signaling, among others. CCND1, ESR1, MMP9, MDM2, NCOA3, and RARA were significantly overexpressed in tumor samples. ATRA showed a high affinity towards CCND1/CDK4 and MMP9. CCND1, ESR1, and MDM2 were associated with poor treatment response and were downregulated after treatment of the breast cancer cell line with ATRA. CCND1 and ESR1 exhibited differential expression across breast cancer stages. Therefore, some part of ATRA's anti-breast cancer activity may be exerted through the CCND1/CDK4 complex.

Virtual and in vitro Screening Employing a Repurposing Approach Reveal 13-Cis-retinoic acid is a PTP1B Inhibitor.

Current treatments for type 2 diabetes (T2D) mainly rely on exercise, dietary control, and anti-diabetic drugs to enhance insulin secretion and improve insulin sensitivity. However, there is a need for more therapeutic options. A potential target that has attracted attention is the protein tyrosine phosphatase 1B (PTP1B), which negatively regulates the insulin signaling pathway. In this work, a comprehensive computational screening was carried out using cheminformatics and molecular docking on PTP1B, employing a rigorous repurposing approach. The screening involved approved drugs and compounds under research as anti-diabetics that bind to targets such as peroxisome proliferator-activated receptor gamma (PPAR-gamma) and alpha-glucosidase. Some computational hits were then meticulously tested in vitro against PTP1B; particularly the 13-cis-retinoic acid ( 3a) showed an IC 50 of 0.044 mM and competitive inhibition. Molecular dynamics studies agrees that 3a can bind to the catalytic binding site of PTP1B. It is worth mentioning that 3a has been reported by the first time as an inhibitor of PTP1B in this work, making it a potentially valuable candidate for further studies in D2T treatment.

Transcriptional and epigenetic characterization of a new in vitro platform to model the formation of human pharyngeal endoderm.

BACKGROUND: The Pharyngeal Endoderm (PE) is an extremely relevant developmental tissue, serving as the progenitor for the esophagus, parathyroids, thyroids, lungs, and thymus. While several studies have highlighted the importance of PE cells, a detailed transcriptional and epigenetic characterization of this important developmental stage is still missing, especially in humans, due to technical and ethical constraints pertaining to its early formation. RESULTS: Here we fill this knowledge gap by developing an in vitro protocol for the derivation of PE-like cells from human Embryonic Stem Cells (hESCs) and by providing an integrated multi-omics characterization. Our PE-like cells robustly express PE markers and are transcriptionally homogenous and similar to in vivo mouse PE cells. In addition, we define their epigenetic landscape and dynamic changes in response to Retinoic Acid by combining ATAC-Seq and ChIP-Seq of histone modifications. The integration of multiple high-throughput datasets leads to the identification of new putative regulatory regions and to the inference of a Retinoic Acid-centered transcription factor network orchestrating the development of PE-like cells. CONCLUSIONS: By combining hESCs differentiation with computational genomics, our work reveals the epigenetic dynamics that occur during human PE differentiation, providing a solid resource and foundation for research focused on the development of PE derivatives and the modeling of their developmental defects in genetic syndromes.

Increased SNAI2 expression and defective collagen adhesion in cells with pediatric dementia, juvenile ceroid lipofuscinosis.

Dementia-related neurodegenerative diseases (NDDs), including Alzheimer's disease (AD), are known to be caused by accumulation of toxic proteins. However, the molecular mechanisms that cause neurodegeneration and its biophysical effects on cells remain unclear. In this study, we used juvenile neuronal ceroid lipofuscinosis (JNCL), a pediatric dementia with a clear etiology of mutations in ceroid lipofuscinosis neuronal 3 (CLN3), to explore the changes in cell adhesion, a biophysical process that regulates neuronal development and survival. We used JNCL cerebral organoid gene expression datasets to identify the biological pathways that affect neural development, and found enriched gene expression in the epithelial-mesenchymal transition (EMT) pathway and increased expression of its inducer snail family transcriptional repressor 2 (SNAI2). A cell adhesion assay using lymphoblasts from patients with JNCL revealed defective adhesion to cell culture plates, glass surfaces, collagen type I, and neuroblast-like cells. To determine whether inhibition of EMT could improve the cell adhesion of JNCL lymphoblasts, we used all-trans retinoic acid, a well-known EMT inhibitor and inducer of neural differentiation. In JNCL lymphoblasts, ATRA treatment enhanced adhesion to collagen type I and these effects were abolished by Ca2+ chelator. These results provide new insights into the role of CLN3 and cell adhesion in the pathogenesis of NDD.

Gut microbiota, vitamin A deficiency and autism spectrum disorder: an interconnected trio - a systematic review.

Accumulating evidence proves that children with autism have gastrointestinal problems. However, a significant difference in gut microbiota (GM) exists between autistic and non-autistic children. These changes in the GM may stem from several factors. Recently, researchers focused on nutritional factors, especially vitamin deficiency. Thus, our systematic review investigates the connections among autism, GM alterations, and vitamin A deficiency (VAD), by analyzing studies sourced from PubMed and Embase databases spanning from 2010 to 2022. Adhering to PRISMA guidelines, we meticulously selected 19 pertinent studies that established links between autism and GM changes or between autism and VAD. Our findings uniformly point to significant alterations in the GM of individuals with autism, indicating these changes as promising biomarkers for the disorder. Despite the consistent association of GM alterations with autism, our analysis revealed no notable differences in GM composition between individuals with autism and those experiencing VAD. This suggests that VAD, especially when encountered early in life, might play a role in the onset of autism. Furthermore, our review underscores a distinct correlation between reduced levels of retinoic acid in children with autism, a disparity that could relate to the severity of autism symptoms. The implications of our findings are twofold: they not only reinforce the significance of GM alterations as potential diagnostic markers but also spotlight the critical need for further research into nutritional interventions. Specifically, vitamin A supplementation emerges as a promising avenue for alleviating autism symptoms, warranting deeper investigation into its therapeutic potential.

In silico analysis of potential inhibitors for breast cancer targeting 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1) catalyses.

Breast cancer (BC) is still one of the major issues in world health, especially for women, which necessitates innovative therapeutic strategies. In this study, we investigated the efficacy of retinoic acid derivatives as inhibitors of 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1), which plays a crucial role in the biosynthesis and metabolism of oestrogen and thereby influences the progression of BC and, the main objective of this investigation is to identify the possible drug candidate against BC through computational drug design approach including PASS prediction, molecular docking, ADMET profiling, molecular dynamics simulations (MD) and density functional theory (DFT) calculations. The result has reported that total eight derivatives with high binding affinity and promising pharmacokinetic properties among 115 derivatives. In particular, ligands 04 and 07 exhibited a higher binding affinity with values of -9.9 kcal/mol and -9.1 kcal/mol, respectively, than the standard drug epirubicin hydrochloride, which had a binding affinity of -8.2 kcal/mol. The stability of the ligand-protein complexes was further confirmed by MD simulations over a 100-ns trajectory, which included assessments of hydrogen bonds, root mean square deviation (RMSD), root mean square Fluctuation (RMSF), dynamic cross-correlation matric (DCCM) and principal component analysis. The study emphasizes the need for experimental validation to confirm the therapeutic utility of these compounds. This study enhances the computational search for new BC drugs and establishes a solid foundation for subsequent experimental and clinical research.

Conditional deletion of CEACAM1 in hepatic stellate cells causes their activation.

OBJECTIVES: Hepatic CEACAM1 expression declines with advanced hepatic fibrosis stage in patients with metabolic dysfunction-associated steatohepatitis (MASH). Global and hepatocyte-specific deletions of Ceacam1 impair insulin clearance to cause hepatic insulin resistance and steatosis. They also cause hepatic inflammation and fibrosis, a condition characterized by excessive collagen production from activated hepatic stellate cells (HSCs). Given the positive effect of PPARγ on CEACAM1 transcription and on HSCs quiescence, the current studies investigated whether CEACAM1 loss from HSCs causes their activation. METHODS: We examined whether lentiviral shRNA-mediated CEACAM1 donwregulation (KD-LX2) activates cultured human LX2 stellate cells. We also generated LratCre + Cc1fl/fl mutants with conditional Ceacam1 deletion in HSCs and characterized their MASH phenotype. Media transfer experiments were employed to examine whether media from mutant human and murine HSCs activate their wild-type counterparts. RESULTS: LratCre + Cc1fl/fl mutants displayed hepatic inflammation and fibrosis but without insulin resistance or hepatic steatosis. Their HSCs, like KD-LX2 cells, underwent myofibroblastic transformation and their media activated wild-type HSCs. This was inhibited by nicotinic acid treatment which blunted the release of IL-6 and fatty acids, both of which activate the epidermal growth factor receptor (EGFR) tyrosine kinase. Gefitinib inhibition of EGFR and its downstream NF-κB/IL-6/STAT3 inflammatory and MAPK-proliferation pathways also blunted HSCs activation in the absence of CEACAM1. CONCLUSIONS: Loss of CEACAM1 in HSCs provoked their myofibroblastic transformation in the absence of insulin resistance and hepatic steatosis. This response is mediated by autocrine HSCs activation of the EGFR pathway that amplifies inflammation and proliferation.

Retinoic acid breakdown is required for proximodistal positional identity during amphibian limb regeneration.

Regenerating limbs retain their proximodistal (PD) positional identity following amputation. This positional identity is genetically encoded by PD patterning genes that instruct blastema cells to regenerate the appropriate PD limb segment. Retinoic acid (RA) is known to specify proximal limb identity, but how RA signaling levels are established in the blastema is unknown. Here, we show that RA breakdown via CYP26B1 is essential for determining RA signaling levels within blastemas. CYP26B1 inhibition molecularly reprograms distal blastemas into a more proximal identity, phenocopying the effects of administering excess RA. We identify Shox as an RA-responsive gene that is differentially expressed between proximally and distally amputated limbs. Ablation of Shox results in shortened limbs with proximal skeletal elements that fail to initiate endochondral ossification. These results suggest that PD positional identity is determined by RA degradation and RA-responsive genes that regulate PD skeletal element formation during limb regeneration.

ALDH1A1 as a marker for metastasis initiating cells: A mechanistic insight.

Since metastasis accounts for the majority of cancer morbidity and mortality, attempts are focused to block metastasis and metastasis initiating cellular programs. It is generally believed that hypoxia, reactive oxygen species (ROS) and the dysregulated redox pathways regulate metastasis. Although induction of epithelial to mesenchymal transition (EMT) can initiate cell motility to different sites other than the primary site, the initiation of a secondary tumor at a distant site depends on self-renewal property of cancer stem cell (CSC) property. That subset of metastatic cells possessing CSC property are referred to as metastasis initiating cells (MICs). Among the different cellular intermediates regulating metastasis in response to hypoxia by inducing EMT and self-renewal property, ALDH1A1 is a critical molecule, which can be used as a marker for MICs in a wide variety of malignancies. The cytosolic ALDHs can irreversibly convert retinal to retinoic acid (RA), which initiates RA signaling, important for self-renewal and EMT. The metastasis permissive tumor microenvironment increases the expression of ALDH1A1, primarily through HIF1α, and leads to metabolic reprograming through OXPHOS regulation. The ALDH1A1 expression and its high activity can reprogram the cancer cells with the transcriptional upregulation of several genes, involved in EMT through RA signaling to manifest hybrid EMT or Hybrid E/M phenotype, which is important for acquiring the characteristics of MICs. Thus, the review on this topic highlights the use of ALDH1A1 as a marker for MICs, and reporters for the marker can be effectively used to trace the population in mouse models, and to screen drugs that target MICs.

Retinoic acid in Parkinson's disease: Molecular insights, therapeutic advances, and future prospects.

Parkinson's disease (PD) is a common and progressively worsening neurodegenerative disorder characterized by abnormal protein homeostasis and the degeneration of dopaminergic neurons, particularly in the substantia nigra pars compacta. The prevalence of PD has doubled in the past 25 years, now affecting over 8.5 million individuals worldwide, underscoring the need for effective management strategies. While current pharmacological therapies provide symptom relief, they face challenges in treating advanced PD stages. Recent research highlights the therapeutic benefits of retinoic acid (RA) in PD, demonstrating its potential to mitigate neuroinflammation and oxidative stress, regulate brain aging, promote neuronal plasticity, and influence circadian rhythm gene expression and retinoid X receptor heterodimerization. Additionally, RA helps maintain intestinal homeostasis and modulates the enteric nervous system, presenting significant therapeutic potential for managing PD. This review explores RA as a promising alternative to conventional therapies by summarizing the molecular mechanisms underlying its role in PD pathophysiology and presenting up-to-date insights into both preclinical and clinical studies of RA in PD treatment. It also delves into cutting-edge formulations incorporating RA, highlighting ongoing efforts to refine therapeutic strategies by integrating RA into novel treatments. This comprehensive overview aims to advance progress in the field, contribute to the development of effective, targeted treatments for PD, and enhance patient well-being. Further research is essential to fully explore RA's therapeutic potential and validate its efficacy in PD treatment.

Chemotherapy-free approaches to newly-diagnosed acute promyelocytic leukaemia: is oral-arsenic trioxide/all-trans retinoic acid/ascorbic acid the answer?

INTRODUCTION: Acute promyelocytic leukemia (APL) is a distinct form of acute myeloid leukemia characterized by the presence of t(15;17)(q24;21) and the PML:RARA gene fusion. Frontline use of intravenous arsenic trioxide (i.v.-ATO) and all-trans retinoic acid (ATRA) has vastly improved cure rates in APL. Researchers in Hong Kong invented the oral formulation of ATO (oral-ATO) and have confirmed a bioavailability comparable to i.v.-ATO. A plethora of studies have confirmed the safety and efficacy of oral-ATO-based regimens in the frontline and relapsed setting. AREAS COVERED: Aspects on the development of oral-ATO-based regimens for APL in the frontline and relapsed setting are discussed. The short-term and long-term safety and efficacy of oral-ATO-based regimens are discussed. The frontline use of oral-ATO in combination with ATRA and ascorbic acid (AAA) induction in a 'chemotherapy-free' is highlighted. EXPERT OPINION: Current and ongoing data on the use of oral-ATO-based regimens in APL support the use of oral-ATO as an alternative to i.v.-ATO allowing a more convenient and economical approach to the management of APL.