Addition Of All-trans Retinoic Acid Research Articles

#2339 All-trans retinoic acid enhances the efficacy of mesenchymal stem cells in acute kidney injury

Abstract Background and Aims Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic strategy for acute kidney injury (AKI), but still suffer from the drawbacks of low survival rate, low homing rate, and uncertain differentiation. In search of better therapeutic strategies, we explored all-trans retinoic acid (ATRA) pretreatment of MSCs to observe whether it could improve the therapeutic efficacy on AKI. Method We established a renal ischemia/reperfusion (I/R) injury model induced by clamping of left renal artery for 30 minutes and contralateral nephrectomy. C57BL/6 mice were randomly divided into 4 groups: sham group, IRI group, MSCs group, and ATRA-MSCs group. MSCs or ATRA-pretreated MSCs were injected via tail vein. GFR was measured by transcutaneous monitoring the clearance of FITC-sinistrin. These mice were sacrificed 3 days after surgery, and the serum creatinine (SCr) and blood urea nitrogen (BUN) levels were measured. The renal pathological changes were examined by Periodic Acid-Schiff staining (PAS). The in vitro hypoxia/reoxygenation (H/R) model was established using human proximal tubular epithelial cells (HK-2 cells). Co-culturing HK-2 cells with MSCs or ATRA-pretreated MSCs. Western blot, quantitative real time-PCR (qRT-PCR), and immunohistochemistry were used to detect mRNA or protein expression. We performed RNA sequencing (RNA-seq) analysis in ATRA-pretreated MSCs. The content of hyaluronic acid (HA) in the supernatant of ATRA-pretreated MSCs culture was detected by ELISA. Hyaluronan synthase mRNA expression level in ATRA-pretreated MSCs assessed by qRT-PCR analysis. The HAS2 promoter-binding transcription factors were forecasted by the JASPAR Transcription Factor Binding Site database. Western blot was used to detect whether P13K/AKT pathway was activated by ATRA-pretreated MSCs. Whether this nephroprotective effect could be reversed were explored by silencing HAS2 or CD44 antibodies. Results The AKI mice showed a significant decrease in GFR and even complete loss of renal function. Administration of MSCs significantly increased GFR, and MSCs pretreated with ATRA further increased GFR. Mice injected with ATRA-pretreated MSCs had significantly lower levels of SCr, BUN and ATN scores compared with untreated MSCs. Western blot, quantitative real-time PCR (qRT-PCR), and immunohistochemistry showed that ATRA pretreated MSCs were more effective in reducing AKI inflammation and apoptosis and promoting proliferative repair than untreated MSCs. GO enrichment analysis demonstrated that the hyaluronan biosynthetic process may be a significantly expressed. HAS2 expression and HA content of MSCS were significantly increased after the addition of ATRA. Analysis for potential transcription factor binding sites revealed that the HAS2 promoter region has multiple potential binding sites for the retinoic acid receptor. Based on the predictions from the JASPAR database, the RXR-RAR heterodimer had the highest prediction score. We then performed ChIP analysis to experimentally verify the binding of RXR-RAR heterodimer transcription factor to HAS2 promoters. We further found that ATRA-pretreated MSCs activated the PI3K/AKT signaling pathway in AKI. As expected, we found that ATRA-pretreated MSCs anti-inflammatory, anti-apoptosis, and pro-proliferation effects were substantially reversed by silencing HAS2 or blocking CD44. Conclusion ATRA promotes HA secretion from MSCs and activates the PI3K/AKT pathway, which in turn enhances the therapeutic efficacy of MSCs on AKI.

Systematic cryopreservation study of cardiac myoblasts in suspension.

H9c2 myoblasts are a cell line derived from embryonic rat heart tissue and demonstrate the ability to differentiate to cardiac myotubes upon reduction of the serum concentration (from 10% to 1%) and addition of all-trans retinoic acid in the growth medium. H9c2 cells are increasingly being used as an easy-to-culture proxy for some functions of cardiomyocytes. The cryobiology of cardiac cells including H9c2 myoblasts has not been studied as extensively as that of some cell types. Consequently, it is important to characterize the cryobiological response and systematically develop well-optimized cryopreservation protocols for H9c2 cells to have optimal and consistent viability and functionality after thaw for high quality studies with this cell type. In this work, an interrupted slow cooling protocol (graded freezing) was applied to characterize H9c2 response throughout the cooling profile. Important factors that affect the cell response were examined, and final protocols that provided the highest post-thaw viability are reported. One protocol uses the common cryoprotectant dimethyl sulfoxide combined with hydroxyethyl starch, which will be suitable for applications in which the presence of dimethyl sulfoxide is not an issue; and the other protocol uses glycerol as a substitute when there is a desire to avoid dimethyl sulfoxide. Both protocols achieved comparable post-thaw viabilities (higher than 80%) based on SYTO 13/GelRed flow cytometry results. H9c2 cells cryopreserved by either protocol showed ability to differentiate to cardiac myotubes comparable to fresh (unfrozen) H9c2 cells, and their differentiation to cardiac myotubes was confirmed with i) change in cell morphology, ii) expression of cardiac marker troponin I, and iii) increase in mitochondrial mass.

Treatment of a TP53 isogenic AML Cell Line Model with Decitabine and All Trans-Retinoic Acid (ATRA) Targets MYC for Antileukemic Activity in a p53-Independent Fashion

Background The DECIDER randomized phase II trial showed that the addition of ATRA to decitabine (DAC) significantly improves survival and overall response rate (ORR) in newly diagnosed elderly AML patients (Lübbert et. al., J Clin Oncol. 2020), with a higher ORR in TP53-mutated (mostly heterozygous) compared to TP53 wildtype. Mechanisms of this in vivo synergism are under study, involving changes in global transcriptome and chromatin accessibility in both TP53wt and TP53mut AML cell lines (Meier et. al., Blood Cancer J. 2022). To further unravel the mechanism of action of DAC+ATRA (D+A) in AML, these studies are now extended to an isogenic TP53 model representing wt vs knock-out. Methods TP53 isogenic MOLM13 cells ( TP53+/+, TP53-/-, Boettcher et al., Science 2019) were treated with 100nM DAC by 3 daily pulses, 250nM ATRA on day 4, and studied for proliferation (EdU), by RNA-sequencing (RNA-seq) and immunofluorescence (IF) at 24, 48 and 72h post ATRA addition. RNA-seq data were analyzed after pre-processing (Cutadapt) and annotation (RNA star) by DEseq2 (adj p-value <0.05, fold change >2), functional enrichment analysis by pyGSEA on ‘50 Hallmark pathways’ using T-statistics on differentially expressed genes (DEGs). Results D+A reduced cell proliferation and increased apoptosis by 88% and 44% in TP53 +/+ cells, by 50% and 15% in TP53 -/- cells relative to control at 48h. By RNA-seq, the global transcriptomic profile of D+A was distinct from single-agent treatment at all 3 timepoints, as the majority of the DEGs were unique to the combination. D+A had 2250 unique DEGs (uDEGs) in TP53 +/+ cells (compared to 192 uDEGs for DAC, 249 uDEGs for ATRA); D+A had 1209 uDEGs in TP53 -/- cells (compared to 328 uDEGs with DAC and 197 uDEGs with ATRA) at 72h. By functional enrichment analysis, we found that D+A requires TP53 for antileukemic activity, as most proliferative pathways (e.g. hallmark G2M checkpoint, hallmark E2F targets) were depleted exclusively in a p53-dependent manner. Interestingly, D+A was able to induce an interferon response and deplete MYC target genes and mTOR signalling independent of p53. As MYC is a known target depleted by D+A, we investigated MYC (by IF) as an additional target for antileukemic activity. We found that global MYC levels were significantly depleted upon ATRA addition to DAC. ATRA depleted MYC levels independent of the TP53 status, while DAC depleted MYC in a p53-dependent manner (Fig. 1A). DAC was able to induce MYC T58 phosphorylation in both TP53 +/+ and TP53 -/- cells (Fig. 1B) but was only able to reduce MYC global levels in TP53+/+ cells, pointing towards a possible p53-dependent perturbation of proteasomal activity. FBXW7 (SCF complex), responsible for ubiquitinating pMYC T58, and USP28 (deubiquitinase) expression levels analysis revealed that USP28 is depleted upon DAC treatment, suggesting that FBXW7 should be able to mark pMYC T58 for ubiquitination and degradation, and further investigation is ongoing to determine proteasomal perturbation and how p53 loss is associated with it. Conclusions Our results represent a mechanistic exploration of how the addition of ATRA was able to enhance DAC's antileukemic activity in two polar opposite TP53 states (intact vs. null). D+A treatment induces a unique molecular signature compared to either drug and targets p53 for an antileukemic effect, but not exclusively, as MYC depletion as well as interferon induction is independent of p53. We also identified p53-dependent perturbation of proteasomal activity, as high amounts of pMYC T58 accumulate in TP53-/- cells upon D+A treatment, and hypothesize that pMYC T58 accumulation results in development of resistance to D+A. These studies will be extended to the most clinically relevant heterozygous TP53 hotspot mutations.

Randomized phase-III study of low-dose cytarabine and etoposide + /− all-trans retinoic acid in older unfit patients with NPM1-mutated acute myeloid leukemia

The aim of this randomized clinical trial was to evaluate the impact of all-trans retinoic acid (ATRA) in combination with non-intensive chemotherapy in older unfit patients (> 60 years) with newly diagnosed NPM1-mutated acute myeloid leukemia. Patients were randomized (1:1) to low-dose chemotherapy with or without open-label ATRA 45 mg/m2, days 8–28; the dose of ATRA was reduced to 45 mg/m2, days 8–10 and 15 mg/m2, days 11–28 after 75 patients due to toxicity. Up to 6 cycles of cytarabine 20 mg/day s.c., bid, days 1–7 and etoposide 100 mg/day, p.o. or i.v., days 1–3 with (ATRA) or without ATRA (CONTROL) were intended. The primary endpoint was overall survival (OS). Between May 2011 and September 2016, 144 patients (median age, 77 years; range, 64–92 years) were randomized (72, CONTROL; 72, ATRA). Baseline characteristics were balanced between the two study arms. The median number of treatment cycles was 2 in ATRA and 2.5 in CONTROL. OS was significantly shorter in the ATRA compared to the CONTROL arm (p = 0.023; median OS: 5 months versus 9.2 months, 2-years OS rate: 7% versus 10%, respectively). Rates of CR/CRi were not different between treatment arms; infections were more common in ATRA beyond treatment cycle one. The addition of ATRA to low-dose cytarabine plus etoposide in an older, unfit patient population was not beneficial, but rather led to an inferior outcome.The clinical trial is registered at clinicaltrialsregister.eu (EudraCT Number: 2010-023409-37, first posted 14/12/2010).

Centella asiatica (L.) Urban. Attenuates Cell Damage in Hydrogen Peroxide-Induced Oxidative Stress in Transgenic Murine Embryonic Stem Cell Line-Derived Neural-Like Cells: A Preliminary Study for Potential Treatment of Alzheimer's Disease.

Centella asiatica (L.) (C. asiatica) is commonly known in South East and South East Asia communities for its nutritional and medicinal benefits. Besides being traditionally used to enhance memory and accelerate wound healing, its phytochemicals have been extensively documented for their neuroprotective, neuroregenerative, and antioxidant properties. The present study aims to investigate the effects of a standardized raw extract of C. asiatica (RECA) on hydrogen peroxide (H2O2)-induced oxidative stress and apoptotic death in neural-like cells derived from mouse embryonic stem cell line. Pre-treatment with H2O2 for 24 hours, in a dose-dependent manner, damaged neural-like cells as marked by a decrease in cell viability, substantial increase in intracellular reactive oxygen species (ROS) accumulation, and increase in apoptotic rate compared to untreated cells. Treatment with RECA for 48 hours remarkably restored cell survival and promoted neurite outgrowth in the H2O2-damaged neurons by increasing cell viability and decreasing ROS activity. RT-qPCR analysis revealed that RECA upregulated the level of antioxidant genes such as thioredoxin-1 (Trx-1) and heme oxygenase-1 (HO-1) of treated cells, as well as the expression level of neuronal-specific markers such as Tuj1 and MAP2 genes, suggesting their contribution in neuritogenic effect. Our findings indicate that RECA promotes neuroregenerative effects and exhibits antioxidant properties, suggesting a valuable synergistic activity of its phytochemical constituents, thus, making the extract a promising candidate in preventing or treating oxidative stress-associated Alzheimer's disease.

Chemotherapy-free treatment for acute promyelocytic leukemia: the pediatric view of a revolutionary tale.

The addition of all-trans retinoic acid (ATRA) to the standard anthracycline-base chemotherapy has revolutionized the treatment of acute promyelocytic leukemia (APL) over the last decades, becoming a model for precision medicine. The protocols based on the combination of ATRA and chemotherapy allowed obtaining excellent response rates both for children and adults. However, the persistence of anthracycline chemotherapy as a backbone was a matter of concern for both acute and long-term complications. Efforts in reducing anthracycline cumulative dose or even eliminating anthracycline have been pursued in more recent pediatric protocols thanks to the introduction of arsenic trioxide (ATO). The impressive results of the ATRA/ATO combinations led to the introduction of protocols completely chemotherapy-free for standard-risk adult patients as the standard of care, whereas pediatric chemo-free protocols are still currently under evaluation. In this Review, we will critically retrace the history of this unique revolution in precision medicine, discussing the peculiar advantages for pediatric patients with APL.

TMIC-72. ALL-TRANS RETINOIC ACID INDUCES DURABLE TUMOR IMMUNITY IN IDH MUTANT GLIOMAS AND CIRCUMVENTS REPRESSION OF CRBP1-RETINOIC ACID AXIS

Abstract Diffuse gliomas are fatal, immunologically cold tumors characterized by mutations in isocitrate dehydrogenase 1 or 2 (IDH1/2) genes. IDH mutations have been shown to result in global genomic hypermethylation and drastically altered transcriptomic landscape. We and others have shown that IDH mutation is direct responsible for the immunological cold landscape observed in IDH mutated glioma. Using a combination of animal models and patient-derived glioma stem cells (GSCs), we identify retinoic acid signaling as a primary regulator of innate and adaptive immune activation in IDHm gliomas. Using the Sleeping Beauty (SB) orthotopic murine model of IDH glioma, which faithfully recapitulates the TME seen in patients, we show that intracellular accumulation of oncometabolite 2-HG leads to hypermethylation and transcriptional repression of Retinol Binding Protein-1 (RBP1), which encode CRBP1, a key chaperone protein required for intracellular all-trans-retinoic-acid biosynthesis in glial cells. Restoration retinoic acid signaling through the addition of all-trans retinoic acid (ATRA) resulted in spontaneous tumor regression and prolonged survival. ATRA administration is further correlated with increased CD8, NK, M1 macrophages and decreased Treg and MDSC populations within the TME. Single-cell sequencing of the TME shows increased type I interferon signaling, myeloid cell polarization, T cell activation, and TCR diversity. Using knockdown and overexpression techniques in patient-derived GSCs, we show that CRBP1 activity is critical for NK mediated immune surveillance and cytotoxicity through regulation of NKG2D ligand expression and immune cell migration through differential regulation of CXCL12 and CCL2. In summary, epigenetic silencing of RBP1 by 2-HG induced hypermethylation leads to a global immune dysregulation resulting in an immunologically cold landscape. Restoration of retinoic acid signaling is a promising immunotherapeutic approach for the treatment of IDHm gliomas.

The role of BMP4 in adipose-derived stem cell differentiation: A minireview.

Bone morphogenetic protein 4 (BMP4) is a member of the transforming growth factor beta (TGF-β) superfamily of cytokines responsible for stem cells' commitment to differentiation, proliferation, and maturation. To date, various studies have utilized BMP4 as a chemical inducer for in vitro differentiation of human mesenchymal stem cells (MSCs) based on its potential. BMP4 drives in vitro differentiation of ADSC via TGF-β signaling pathway by interactions with BMP receptors leading to the activation of smad-dependent and smad-independent pathways. The BMP4 signaling pathways are regulated by intracellular and extracellular BMP4 antagonists. Extracellular BMP4 antagonist prevents interaction between BMP4 ligand to its receptors, while intracellular BMP4 antagonist shutdowns the smad-dependent pathways through multiple mechanisms. BMP4 proved as one of the popular differentiation factors to induce ADSC differentiation into cell from mesodermal origin. However, addition of all-trans retinoic acid is also needed in trans-differentiation of ADSC into ectodermal lineage cells. Suggesting that both BMP4 and RA signaling pathways may be necessary to be activated for in vitro trans-differentiation of ADSC.

All-trans retinoic acid-mediated miR-30a up-regulation suppresses autophagy and sensitizes gastric cancer cells to cisplatin

AimsThe potential of all-trans retinoic acid (ATRA) in regulating some microRNAs (miRNAs) involved in multiple cancer-related pathways, including resistance to chemotherapeutics, may be a valuable idea for overcoming the CDDP resistance of GC cells. Main methodsTreatment of gastric AGS and MKN-45 cells with CDDP enriched the CDDP surviving cells (CDDP-SCs). The abilities of chemoresistance to CDDP drug, migration, either apoptosis or cell cycle distribution, spheroid body formation and changes at miRNA and protein levels were evaluated in vitro by MTT assay, colony formation assay, flow cytometry, tumor spheres culture, qRT-PCR and western blot assay in CDDP-SCs and ATRA-treated CDDP-SCs cells, respectively. Key findingsCDDP-based chemotherapy significantly reduced microRNA-30a (miR-30a) levels in GC cells. We also observed elevated autophagy activity in cancer cells that possess stem cell-like properties with overexpressed specific stem cell markers. Our extended study suggested that the reduction of miR-30a by CDDP treatment, is the possible underlying mechanism of enhanced autophagic activity, as demonstrated by enhancing autophagy-related protein beclin 1 and LC3-II/LC-I ratio. The addition of ATRA in the culture medium of GC cells increased the expression of miR-30a, and disturbed characteristic CSC-like properties. Additional studies revealed that the increased expression of miR-30a declined the expression level of its target gene, beclin 1, and beclin 1-mediated autophagy. This leads to promoted CDDP-induced GC cell apoptosis and G2/M cell cycle arrest. SignificanceOverall, miR-30a/autophagy signaling has a critical role in regulating the chemoresistance of GC cells that ATRA could modulate.

A new application of surfactant-free microemulsion: Solubilization and transport of drugs and its transdermal release properties

BackgroundSurfactant-free microemulsion (SFME) has been used in the application of enzyme catalysis, material synthesis and raw material extraction but no research on nano drug carriers. MethodA novel green SFME with eucalyptus oil as the oil phase was developed as representative for solubilizing unstable and insoluble all-trans retinoic acid (ATRA), enhancing its stability and promoting its transdermal absorption. This work was investigated by experiment combined with simulation. Significant findingsATRA solubilization occurs in oil-in-water droplet of SFME and the dissolution process is spontaneous. The droplet sizes of ATRA-loaded SFMEs increase with the addition of ATRA. The solubility of ATRA is notably increased by SFME (10.08 × 103 μg·mL−1), 53,000 times higher than that in water and 504 times in silicone oil. Compared with previous studies, ATRA-loaded SFMEs have better light, thermal and centrifugal stability as well as oxidation resistance than ATRA-loaded silicone oil. All the droplet sizes of ATRA-loaded SFMEs are smaller than that reported, therefore, a better transdermal absorption effect is exhibited compared to ATRA-loaded azone. The transdermal release of ATRA is consistent with Korsmeyer-Peppas kinetic model. This research would be a pioneer in the new application field of SFME.

A Double Payload Complex between Hypericin and All-trans Retinoic Acid in the β-Lactoglobulin Protein

Combined therapies are usually used to treat acne vulgaris since this approach can tackle various foci simultaneously. Using a combination of spectroscopic, computational, and microbiological techniques and methods, herein we report on the use of β-lactoglobulin as a double payload carrier of hypericin (an antimicrobial photodynamic agent) and all-trans retinoic acid (an anti-inflammatory drug) for S. aureus in vitro photodynamic inactivation. The addition of all-trans retinoic acid to hypericin-β-lactoglobulin complex renders a photochemically safe vehicle due to the photophysical quenching of hypericin, which recovers its photodynamic activity when in contact with bacteria. The ability of hypericin to photoinactivate S. aureus was not affected by retinoic acid. β-Lactoglobulin is a novel biocompatible and photochemically safe nanovehicle with strong potential for the treatment of acne.

Combination of Decitabine and ATRA in Newly Diagnosed Myelodysplastic Syndromes Subtype EB-Interim Analysis of a Multicenter, Randomized, Open-Label Trial

Background: HMAs are mainstay treatment of higher-risk myelodysplastic syndromes (MDS). However, clinical outcomes of patients treated with decitabine (DEC) monotherapy were far from satisfactory with an overall response rate (ORR) of 33%-55.4% and an overall survival (OS) of 17.7-22 months. Some clinical researches reported that the addition of all-trans retinoic acid (ATRA) to DEC increased response rate and prolonged survival of MDS and elderly acute myeloid leukemia (AML) patients. Our data showed ATRA enhanced the cytotoxic effect of DEC on MDS via activating RARα-Nrf2 complex (2021 EHA abstract EP891). These findings suggested that addition of ATRA to DEC in treatment-naive patients may improve response rate based on the synergetic function. We therefore conducted a study of combination of DEC and ATRA in MDS subtype excessive blasts (EB) patients.Methods: In this randomized, multicenter, open-label trial, patients with newly diagnosed MDS subtype EB based on the 2016 WHO classification from 7 different tertiary medical centers in China were included. Patients were randomized 1:1 to receive either oral ATRA (25mg/m 2/day on days 1-28) plus DEC (20 mg/m 2 daily on days 1-5) or DEC monotherapy（Figure 1）. The primary endpoint was overall response rate ORR, defined as complete remission (CR), partial remission (PR), marrow complete remission (mCR), or hematological improvement (HI). Key secondary endpoints were mCR, HI, overall survival (OS), and progress free survival (PFS). Response was assessed after completion of four cycles of treatment. For patients who bridged to allo-HSCT later on and did not complete four cycles of treatments, response was defined as best response ever observed before receiving allo-HSCT. Here, we report results of the interim analysis.Results: Between May 2018 and July 2021, 165 patients were randomly allocated into either DEC plus ATRA (n=82) or DEC monotherapy (n=83). 63.6% of patients were male and 36.4% were female, with a median age of 62 years (range, 19 to 81 years). 38.8% of patients had EB1 and 61.2% had EB2. As of July 31, 2021, 126 patients were available for the assessment of treatment results.After a median follow up of 9.6 months, median number of courses on treatment was 4 courses (range, 1-14), 61 in DEC plus ATRA arm and 65 in DEC arm . OR was achieved in 85.2% of DEC plus ATRA patients compared to 56.9% in DEC monotherapy (p<0.001). mCR rate was 73.8% in patients treated with DEC plus ATRA and 53.8% in those with DEC monotherapy (p=0.02). HI rate was 63.9% and 44.6% in patients with DEC plus ATRA and DEC monotherapy, respectively (p=0.03). The median OS and PFS were 18.8 months and 13.5 months for DEC plus ATRA arms, 19.2 months and 13.0 months for in DEC arm, respectively.72.7% patients developed at least one adverse event (AE) during the trial, 73.3% in the DEC plus ATRA arm and 72.0% in DEC arm, respectively. Grade 3/4 Hematological toxicity occurred in 73.68 % of DEC plus ATRA arm and 76.92 % of DEC arm. Hyperlipidemia occurred in 31 patients in DEC plus ATRA arm (3.2% grade 3/4), and 18 (no grade 3/4) in DEC arm (p<0.001). Incidence of headache was higher in DEC plus ATRA arm (14.7% vs 4.0% in DEC arm, respectively, p<0.001). No other statistically significant differences were observed in the incidence of treatment-related AEs between the two groups. No early death occurred.Conclusion: Combination of DEC and ATRA achieved an OR rate of 85.2% in MDS subtype EB. Enrollment is ongoing to assess its efficacy and safety in treating EB. This therapy may be a new treatment option for EB subjects. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

All-trans retinoic acid alters the expression of adipogenic genes during the differentiation of bovine intramuscular and subcutaneous adipocytes

The present study was designed to determine the influence of all-trans retinoic acid (ATRA) on adipogenesis-related gene regulation in bovine intramuscular (IM) and subcutaneous (SC) adipose cells during differentiation. Bovine IM and SC adipocytes were isolated from three 19-mo-old, crossbred steers. Adipogenic differentiation was induced upon cultured IM and SC preadipocytes with various doses (0, 0.001, 0.01, 0.1, 1 µM) of ATRA. After 96 h of incubation, cells were harvested and used to measure the gene expression of CCAAT/Enhancer binding protein β (C/EBPβ), peroxisome proliferator-activated receptor (PPAR) γ, glucose transporter 4 (GLUT4), stearoyl CoA desaturase (SCD), and Smad transcription factor 3 (Smad3) relative to the quantity of ribosomal protein subunit 9 (RPS 9). Retinoic acid receptor (RAR) antagonist also tested to identify the effect of ATRA on PPARγ -RAR related gene expression in IM cells. The addition of ATRA to bovine IM decreased (p < 0.05) expression of PPARγ. The expression of PPARγ was also tended to be downregulated (p < 0.1) in high levels (10 μM) of ATRA treatment in SC cells. The treatment of RAR antagonist increased the expression of PPARγ in IM cells. Expression of C/EBPβ decreased (p < 0.05) in SC, but no change was observed in IM (p > 0.05). Increasing levels of ATRA may block adipogenic differentiation via transcriptional regulation of PPARγ. The efficacy of ATRA treatment in adipose cells may vary depending on the location.

Efficacy and safety of daratumumab combined with all-trans retinoic acid in relapsed/refractory multiple myeloma

AbstractThe efficacy of daratumumab depends partially on CD38 expression on multiple myeloma (MM) cells. We have previously shown that all-trans retinoic acid (ATRA) upregulates CD38 expression and reverts daratumumab-resistance ex vivo. We therefore evaluated the optimal dose, efficacy, and safety of daratumumab combined with ATRA in patients with daratumumab-refractory MM in a phase 1/2 study (NCT02751255). In part A of the study, 63 patients were treated with daratumumab monotherapy. Fifty patients with daratumumab-refractory MM were subsequently enrolled in part B and treated with daratumumab (reintensified schedule) combined with ATRA until disease progression. The recommended phase 2 dose of ATRA in combination with daratumumab was defined as 45 mg/m2. At this dose, the overall response rate (ORR) was 5%, indicating that the primary endpoint (ORR ≥15%) was not met. However, most patients (66%) achieved at least stable disease. After a median follow-up of 43 months, the median progression-free survival (PFS) for all patients was 2.8 months. Patients who previously achieved at least a partial response or minimal response/stable disease with prior daratumumab monotherapy had a significantly longer PFS compared with patients who immediately progressed during daratumumab as single agent (median PFS 3.4 and 2.8 vs 1.3 months). The median overall survival was 19.1 months. The addition of ATRA did not increase the incidence of adverse events. Flow cytometric analysis revealed that ATRA temporarily increased CD38 expression on immune cell subsets. In conclusion, the addition of ATRA and reintensification of daratumumab had limited activity in patients with daratumumab-refractory MM, which may be explained by the transient upregulation of CD38 expression. This trial was registered at www.clinicaltrials.gov as #NCT02751255.

Activity of Decitabine (DAC) Combined with All-Trans Retinoic Acid (ATRA) in Oligoblastic AML: Subgroup Analysis of a Randomized 2x2 Phase II Trial

Activity of Decitabine (DAC) Combined with All-Trans Retinoic Acid (ATRA) in Oligoblastic AML: Subgroup Analysis of a Randomized 2x2 Phase II Trial

Asymptomatic neurotoxicity of amyloid β-peptides (Aβ1-42 and Aβ25-35) on mouse embryonic stem cell-derived neural cells.

One of the strategies in the establishment of in vitro oxidative stress models for neurodegenerative diseases, such as Alzheimer’s disease (AD), is to induce neurotoxicity by amyloid beta (Aβ) peptides in suitable neural cells. Presently, data on the neurotoxicity of Aβ in neural cells differentiated from stem cells are limited. In this study, we attempted to induce oxidative stress in transgenic 46C mouse embryonic stem cell-derived neurons via treatment with Aβ peptides (Aβ1-42 and Aβ25-35). 46C neural cells were generated by promoting the formation of multicellular aggregates, embryoid bodies in the absence of leukemia inhibitory factor, followed by the addition of all-trans retinoic acid as the neural inducer. Mature neuronal cells were exposed to different concentrations of Aβ1-42 and Aβ25-35 for 24 h. Morphological changes, cell viability, and intracellular reactive oxygen species (ROS) production were assessed. We found that 100 μM Aβ1-42 and 50 μM Aβ25-35 only promoted 40% and 10%, respectively, of cell injury and death in the 46C-derived neuronal cells. Interestingly, treatment with each of the Aβ peptides resulted in a significant increase of intracellular ROS activity, as compared to untreated neurons. These findings indicate the potential of using neurons derived from stem cells and Aβ peptides in generating oxidative stress for the establishment of an in vitro AD model that could be useful for drug screening and natural product studies.

All-Trans Retinoic Acid Synergizes with Enasidenib to Induce Differentiation of IDH2-Mutant Acute Myeloid Leukemia Cells.

PurposePharmacological inhibition of mutant isocitrate dehydrogenase (IDH) reduces R-2-hydroxyglutarate (2-HG) levels and restores cellular differentiation in vivo and in vitro. The IDH2 inhibitor enasidenib (AG-221) has been approved by the FDA as a first-in-class inhibitor for the treatment of relapsed or refractory (R/R) IDH2-mutant acute myeloid leukemia (AML). In this study, the effects of a combination of all-trans retinoic acid (ATRA) and AG-221 on AML cell differentiation was explored, along with the mechanisms employed by IDH2-mutant cells in AML.Materials and MethodsWe treated the human AML cell line, IDH2-mutant-TF-1, and primary human AML cells carrying IDH2 mutation with 30 µM AG-221 and 100 nM ATRA, alone or in combination.ResultsCombined treatment with AG-221 and ATRA inhibited 2-HG production and resulted in synergistic effects on differentiation among IDH2-mutant AML cells and primary AML cells expressing IDH2 mutation. Combined treatment with AG-221 and ATRA altered autophagic activity. AG-221 and ATRA treatment-induced differentiation of IDH2-mutant AML cells was associated with autophagy induction, without suppressing autophagy flux at maturation and degradation stages. A RAF-1/MEK/ERK pathway was founded to be associated with AG-221 and ATRA-induced differentiation in IDH2-mutant AML cells. IDH-associated changes in histone methylation markers decreased after AG-221 and ATRA combination treatment.ConclusionOur preliminary evidence indicates that the addition of ATRA to treatments with IDH2 inhibitor may lead to further improvements or increases in response rates in IDH2-mutant AML patients who do not appear to benefit from treatments with IDH2 inhibitor alone.

Efficacy and Safety of Daratumumab Combined with All-Trans Retinoic Acid in Relapsed/Refractory Multiple Myeloma; Results of the Phase 1/2 Dara/ATRA Study

Efficacy and Safety of Daratumumab Combined with All-Trans Retinoic Acid in Relapsed/Refractory Multiple Myeloma; Results of the Phase 1/2 Dara/ATRA Study

Combination of ATRA and High-Dose Dexamethasone As First-Line Treatment in Adult Immune Thrombocytopenia:a Randomized, Phase 2, Open-Label Trial

Introductions Immune thrombocytopenia (ITP) is an acquired thrombocytopenia caused by immune-mediated platelet destruction and impaired platelet production. As the immunosuppressive therapy, high-dose dexamethasone (HD-DXM) has been recommended as the standard first-line treatment. Nevertheless, approximately half of ITP patients relapse within 6 months and require further therapies. All-trans retinoic acid (ATRA) is a derivative of vitamin A that has an immunomodulatory effect on hemopoiesis. Our previous study demonstrated that ATRA could induce a more rapid and long-lasting response in patients with corticosteroid-resistant or relapsed ITP (Lancet haematology, 2017). In addition, we found that ATRA corrected impaired platelet production by regulating the complement-IL-1β loop and TNFAIP3/NF-κB/SMAD7 signaling pathway in ITP (Br J Haematol, 2018; Haematologica, 2019). These findings suggested that the addition of ATRA to HD-DXM in treatment-naive patients could improve sustained response rate based on the synergetic function. Here, we present the results of the first prospective, multicenter, randomized, controlled trial with the largest cohort to date comparing the efficacy and safety of HD-DXM plus ATRA vs HD-DXM as first-line therapy in newly diagnosed adult primary ITP patients. Methods In this open-label, randomized, phase 2 trial, we enrolled adult ITP patients from 6 different tertiary medical centers in China. Eligible subjects had confirmed newly-diagnosed, treatment-naive ITP; platelet counts &amp;lt;30×109/L or platelet counts &amp;lt; 50×109/L and significant bleeding symptoms (WHO bleeding scale 2 or above).Eligible patients were randomly assigned 1:1 with an interactive web-based response system to receive either oral ATRA (10 mg twice daily) plus HD-DXM or HD-DXM monotherapy for 12 weeks. DXM was administered orally at 40 mg daily for 4 consecutive days to both arms. The 4-day course of dexamethasone was repeated on days 11 to 14 in the case of lack of response by day 10(Figure 1). The primary endpoint was 6-month sustained response (SR) defined as platelet counts maintained &amp;gt; 50×109/L without any additional ITP-modifying therapy at the 6-month follow up. Key secondary endpoints were initial response by day 14 (OR: platelet count ≥30×109/L and at least 2-fold increase of the baseline platelet count and absence of bleeding; CR: platelet count ≥100×109/L), duration of response (DOR), bleeding scores, and adverse events (AEs). Results Between June 2015, and July 2018, 300 patients were randomly allocated into either ATRA plus HD-DXM (n=150) or HD-DXM monotherapy (n=150). At the 6-month follow-up, the proportion of patients with SR was significantly higher in the ATRA plus HD-DXM group than in the HD-DXM monotherapy group (61% vs 37%, p= 0.009). So far, the increase of almost one quarter is very encouraging. The combination of ATRA and HD-DXM resulted in a higher incidence of early OR at day 14 compared with HD-DXM monotherapy (83% vs 67%, P=0.031), and the CR rate was 60.0% (ATRA+HD-DXM) vs 40.6% (HD-DXM) (P=0.015). Throughout the follow-up period, overall DOR was greater in the combination group, estimated by the Kaplan-Meier analysis. Fewer patients in the combination group than in the monotherapy group relapsed during follow-up (p&amp;lt; 0.001), and the median time to relapse was 75 days (ATRA+HD-DXM) vs 48 days (HD-DXM). Bleeding was more effectively controlled in the ATRA plus HD-DXM arm, with fewer bleeding events and lower bleeding scores. There was no difference between the 2 groups in terms of rescue treatments. All subjects tolerated the treatment well, and no grade 4 adverse events or treatment-related death were reported. No statistically significant differences were observed in the incidence of treatment-related AEs between the two groups. Conclusions ATRA plus HD-DXM is an effective and safe treatment for ITP as a first-line therapy that can provide a sustained prolonged response in adults. This therapy could be a new treatment option for ITP subjects. Disclosures No relevant conflicts of interest to declare.

To PARP or not to PARP?-Toward sensitizing acute myeloid leukemia stem cells to immunotherapy.

A new study reveals that leukemia stem cells (LSCs) in acute myeloid leukemia downregulate natural killer cell-activating receptor ligands to evade immune surveillance via the transcriptional co-factor PARP1. The inhibition of PARP1 sensitizes LSCs to immunotherapy, highlighting its potential as a therapeutic target.